relocate applypatch; add type system and new functions to edify

- Move applypatch to this package (from build).

- Add a rudimentary type system to edify:  instead of just returning a
  char*, functions now return a Value*, which is a struct that can
  carry different types of value (currently just STRING and BLOB).
  Convert all functions to this new scheme.

- Change the one-argument form of package_extract_file to return a
  Value of the new BLOB type.

- Add read_file() to load a local file and return a blob, and
  sha1_check() to test a blob (or string) against a set of possible
  sha1s.  read_file() uses the file-loading code from applypatch so it
  can read MTD partitions as well.

This is the start of better integration between applypatch and the
rest of edify.

b/2361316 - VZW Issue PP628: Continuous reset to Droid logo:
            framework-res.apk update failed (CR LIBtt59130)

Change-Id: Ibd038074749a4d515de1f115c498c6c589ee91e5

22 files changed, 4239 insertions, 112 deletions

diff --git a/Android.mk b/Android.mk
index 5f74064..c556db3 100644
--- a/Android.mk
+++ b/Android.mk
@@ -65,6 +65,7 @@ include $(commands_recovery_local_path)/mtdutils/Android.mk
 include $(commands_recovery_local_path)/tools/Android.mk
 include $(commands_recovery_local_path)/edify/Android.mk
 include $(commands_recovery_local_path)/updater/Android.mk
+include $(commands_recovery_local_path)/applypatch/Android.mk
 commands_recovery_local_path :=
 
 endif   # TARGET_ARCH == arm
diff --git a/applypatch/Android.mk b/applypatch/Android.mk
new file mode 100644
index 0000000..d20d6c8
--- /dev/null
+++ b/applypatch/Android.mk
@@ -0,0 +1,59 @@
+# Copyright (C) 2008 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+ifneq ($(TARGET_SIMULATOR),true)
+
+LOCAL_PATH := $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := applypatch.c bspatch.c freecache.c imgpatch.c utils.c
+LOCAL_MODULE := libapplypatch
+LOCAL_MODULE_TAGS := eng
+LOCAL_C_INCLUDES += external/bzip2 external/zlib bootable/recovery
+LOCAL_STATIC_LIBRARIES += libmtdutils libmincrypt libbz libz
+
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := main.c
+LOCAL_MODULE := applypatch
+LOCAL_STATIC_LIBRARIES += libapplypatch libmtdutils libmincrypt libbz
+LOCAL_SHARED_LIBRARIES += libz libcutils libstdc++ libc
+
+include $(BUILD_EXECUTABLE)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := main.c
+LOCAL_MODULE := applypatch_static
+LOCAL_FORCE_STATIC_EXECUTABLE := true
+LOCAL_MODULE_TAGS := eng
+LOCAL_STATIC_LIBRARIES += libapplypatch libmtdutils libmincrypt libbz
+LOCAL_STATIC_LIBRARIES += libz libcutils libstdc++ libc
+
+include $(BUILD_EXECUTABLE)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := imgdiff.c utils.c bsdiff.c
+LOCAL_MODULE := imgdiff
+LOCAL_FORCE_STATIC_EXECUTABLE := true
+LOCAL_MODULE_TAGS := eng
+LOCAL_C_INCLUDES += external/zlib external/bzip2
+LOCAL_STATIC_LIBRARIES += libz libbz
+
+include $(BUILD_HOST_EXECUTABLE)
+
+endif  # !TARGET_SIMULATOR
diff --git a/applypatch/applypatch.c b/applypatch/applypatch.c
new file mode 100644
index 0000000..daf3729
--- /dev/null
+++ b/applypatch/applypatch.c
@@ -0,0 +1,900 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "mincrypt/sha.h"
+#include "applypatch.h"
+#include "mtdutils/mtdutils.h"
+
+int SaveFileContents(const char* filename, FileContents file);
+int LoadMTDContents(const char* filename, FileContents* file);
+int ParseSha1(const char* str, uint8_t* digest);
+ssize_t FileSink(unsigned char* data, ssize_t len, void* token);
+
+static int mtd_partitions_scanned = 0;
+
+// Read a file into memory; store it and its associated metadata in
+// *file.  Return 0 on success.
+int LoadFileContents(const char* filename, FileContents* file) {
+  file->data = NULL;
+
+  // A special 'filename' beginning with "MTD:" means to load the
+  // contents of an MTD partition.
+  if (strncmp(filename, "MTD:", 4) == 0) {
+    return LoadMTDContents(filename, file);
+  }
+
+  if (stat(filename, &file->st) != 0) {
+    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+    return -1;
+  }
+
+  file->size = file->st.st_size;
+  file->data = malloc(file->size);
+
+  FILE* f = fopen(filename, "rb");
+  if (f == NULL) {
+    printf("failed to open \"%s\": %s\n", filename, strerror(errno));
+    free(file->data);
+    file->data = NULL;
+    return -1;
+  }
+
+  size_t bytes_read = fread(file->data, 1, file->size, f);
+  if (bytes_read != file->size) {
+    printf("short read of \"%s\" (%d bytes of %d)\n",
+            filename, bytes_read, file->size);
+    free(file->data);
+    file->data = NULL;
+    return -1;
+  }
+  fclose(f);
+
+  SHA(file->data, file->size, file->sha1);
+  return 0;
+}
+
+static size_t* size_array;
+// comparison function for qsort()ing an int array of indexes into
+// size_array[].
+static int compare_size_indices(const void* a, const void* b) {
+  int aa = *(int*)a;
+  int bb = *(int*)b;
+  if (size_array[aa] < size_array[bb]) {
+    return -1;
+  } else if (size_array[aa] > size_array[bb]) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+void FreeFileContents(FileContents* file) {
+    if (file) free(file->data);
+    free(file);
+}
+
+// Load the contents of an MTD partition into the provided
+// FileContents.  filename should be a string of the form
+// "MTD:<partition_name>:<size_1>:<sha1_1>:<size_2>:<sha1_2>:...".
+// The smallest size_n bytes for which that prefix of the mtd contents
+// has the corresponding sha1 hash will be loaded.  It is acceptable
+// for a size value to be repeated with different sha1s.  Will return
+// 0 on success.
+//
+// This complexity is needed because if an OTA installation is
+// interrupted, the partition might contain either the source or the
+// target data, which might be of different lengths.  We need to know
+// the length in order to read from MTD (there is no "end-of-file"
+// marker), so the caller must specify the possible lengths and the
+// hash of the data, and we'll do the load expecting to find one of
+// those hashes.
+int LoadMTDContents(const char* filename, FileContents* file) {
+  char* copy = strdup(filename);
+  const char* magic = strtok(copy, ":");
+  if (strcmp(magic, "MTD") != 0) {
+    printf("LoadMTDContents called with bad filename (%s)\n",
+            filename);
+    return -1;
+  }
+  const char* partition = strtok(NULL, ":");
+
+  int i;
+  int colons = 0;
+  for (i = 0; filename[i] != '\0'; ++i) {
+    if (filename[i] == ':') {
+      ++colons;
+    }
+  }
+  if (colons < 3 || colons%2 == 0) {
+    printf("LoadMTDContents called with bad filename (%s)\n",
+            filename);
+  }
+
+  int pairs = (colons-1)/2;     // # of (size,sha1) pairs in filename
+  int* index = malloc(pairs * sizeof(int));
+  size_t* size = malloc(pairs * sizeof(size_t));
+  char** sha1sum = malloc(pairs * sizeof(char*));
+
+  for (i = 0; i < pairs; ++i) {
+    const char* size_str = strtok(NULL, ":");
+    size[i] = strtol(size_str, NULL, 10);
+    if (size[i] == 0) {
+      printf("LoadMTDContents called with bad size (%s)\n", filename);
+      return -1;
+    }
+    sha1sum[i] = strtok(NULL, ":");
+    index[i] = i;
+  }
+
+  // sort the index[] array so it indexes the pairs in order of
+  // increasing size.
+  size_array = size;
+  qsort(index, pairs, sizeof(int), compare_size_indices);
+
+  if (!mtd_partitions_scanned) {
+    mtd_scan_partitions();
+    mtd_partitions_scanned = 1;
+  }
+
+  const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+  if (mtd == NULL) {
+    printf("mtd partition \"%s\" not found (loading %s)\n",
+            partition, filename);
+    return -1;
+  }
+
+  MtdReadContext* ctx = mtd_read_partition(mtd);
+  if (ctx == NULL) {
+    printf("failed to initialize read of mtd partition \"%s\"\n",
+            partition);
+    return -1;
+  }
+
+  SHA_CTX sha_ctx;
+  SHA_init(&sha_ctx);
+  uint8_t parsed_sha[SHA_DIGEST_SIZE];
+
+  // allocate enough memory to hold the largest size.
+  file->data = malloc(size[index[pairs-1]]);
+  char* p = (char*)file->data;
+  file->size = 0;                // # bytes read so far
+
+  for (i = 0; i < pairs; ++i) {
+    // Read enough additional bytes to get us up to the next size
+    // (again, we're trying the possibilities in order of increasing
+    // size).
+    size_t next = size[index[i]] - file->size;
+    size_t read = 0;
+    if (next > 0) {
+      read = mtd_read_data(ctx, p, next);
+      if (next != read) {
+        printf("short read (%d bytes of %d) for partition \"%s\"\n",
+                read, next, partition);
+        free(file->data);
+        file->data = NULL;
+        return -1;
+      }
+      SHA_update(&sha_ctx, p, read);
+      file->size += read;
+    }
+
+    // Duplicate the SHA context and finalize the duplicate so we can
+    // check it against this pair's expected hash.
+    SHA_CTX temp_ctx;
+    memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
+    const uint8_t* sha_so_far = SHA_final(&temp_ctx);
+
+    if (ParseSha1(sha1sum[index[i]], parsed_sha) != 0) {
+      printf("failed to parse sha1 %s in %s\n",
+              sha1sum[index[i]], filename);
+      free(file->data);
+      file->data = NULL;
+      return -1;
+    }
+
+    if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_SIZE) == 0) {
+      // we have a match.  stop reading the partition; we'll return
+      // the data we've read so far.
+      printf("mtd read matched size %d sha %s\n",
+             size[index[i]], sha1sum[index[i]]);
+      break;
+    }
+
+    p += read;
+  }
+
+  mtd_read_close(ctx);
+
+  if (i == pairs) {
+    // Ran off the end of the list of (size,sha1) pairs without
+    // finding a match.
+    printf("contents of MTD partition \"%s\" didn't match %s\n",
+            partition, filename);
+    free(file->data);
+    file->data = NULL;
+    return -1;
+  }
+
+  const uint8_t* sha_final = SHA_final(&sha_ctx);
+  for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+    file->sha1[i] = sha_final[i];
+  }
+
+  // Fake some stat() info.
+  file->st.st_mode = 0644;
+  file->st.st_uid = 0;
+  file->st.st_gid = 0;
+
+  free(copy);
+  free(index);
+  free(size);
+  free(sha1sum);
+
+  return 0;
+}
+
+
+// Save the contents of the given FileContents object under the given
+// filename.  Return 0 on success.
+int SaveFileContents(const char* filename, FileContents file) {
+  int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
+  if (fd < 0) {
+    printf("failed to open \"%s\" for write: %s\n",
+            filename, strerror(errno));
+    return -1;
+  }
+
+  size_t bytes_written = FileSink(file.data, file.size, &fd);
+  if (bytes_written != file.size) {
+    printf("short write of \"%s\" (%d bytes of %d) (%s)\n",
+           filename, bytes_written, file.size, strerror(errno));
+    close(fd);
+    return -1;
+  }
+  fsync(fd);
+  close(fd);
+
+  if (chmod(filename, file.st.st_mode) != 0) {
+    printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
+  if (chown(filename, file.st.st_uid, file.st.st_gid) != 0) {
+    printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
+
+  return 0;
+}
+
+// Write a memory buffer to target_mtd partition, a string of the form
+// "MTD:<partition>[:...]".  Return 0 on success.
+int WriteToMTDPartition(unsigned char* data, size_t len,
+                        const char* target_mtd) {
+  char* partition = strchr(target_mtd, ':');
+  if (partition == NULL) {
+    printf("bad MTD target name \"%s\"\n", target_mtd);
+    return -1;
+  }
+  ++partition;
+  // Trim off anything after a colon, eg "MTD:boot:blah:blah:blah...".
+  // We want just the partition name "boot".
+  partition = strdup(partition);
+  char* end = strchr(partition, ':');
+  if (end != NULL)
+    *end = '\0';
+
+  if (!mtd_partitions_scanned) {
+    mtd_scan_partitions();
+    mtd_partitions_scanned = 1;
+  }
+
+  const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+  if (mtd == NULL) {
+    printf("mtd partition \"%s\" not found for writing\n", partition);
+    return -1;
+  }
+
+  MtdWriteContext* ctx = mtd_write_partition(mtd);
+  if (ctx == NULL) {
+    printf("failed to init mtd partition \"%s\" for writing\n",
+            partition);
+    return -1;
+  }
+
+  size_t written = mtd_write_data(ctx, (char*)data, len);
+  if (written != len) {
+    printf("only wrote %d of %d bytes to MTD %s\n",
+            written, len, partition);
+    mtd_write_close(ctx);
+    return -1;
+  }
+
+  if (mtd_erase_blocks(ctx, -1) < 0) {
+    printf("error finishing mtd write of %s\n", partition);
+    mtd_write_close(ctx);
+    return -1;
+  }
+
+  if (mtd_write_close(ctx)) {
+    printf("error closing mtd write of %s\n", partition);
+    return -1;
+  }
+
+  free(partition);
+  return 0;
+}
+
+
+// Take a string 'str' of 40 hex digits and parse it into the 20
+// byte array 'digest'.  'str' may contain only the digest or be of
+// the form "<digest>:<anything>".  Return 0 on success, -1 on any
+// error.
+int ParseSha1(const char* str, uint8_t* digest) {
+  int i;
+  const char* ps = str;
+  uint8_t* pd = digest;
+  for (i = 0; i < SHA_DIGEST_SIZE * 2; ++i, ++ps) {
+    int digit;
+    if (*ps >= '0' && *ps <= '9') {
+      digit = *ps - '0';
+    } else if (*ps >= 'a' && *ps <= 'f') {
+      digit = *ps - 'a' + 10;
+    } else if (*ps >= 'A' && *ps <= 'F') {
+      digit = *ps - 'A' + 10;
+    } else {
+      return -1;
+    }
+    if (i % 2 == 0) {
+      *pd = digit << 4;
+    } else {
+      *pd |= digit;
+      ++pd;
+    }
+  }
+  if (*ps != '\0' && *ps != ':') return -1;
+  return 0;
+}
+
+// Parse arguments (which should be of the form "<sha1>" or
+// "<sha1>:<filename>" into the array *patches, returning the number
+// of Patch objects in *num_patches.  Return 0 on success.
+int ParseShaArgs(int argc, char** argv, Patch** patches, int* num_patches) {
+  *num_patches = argc;
+  *patches = malloc(*num_patches * sizeof(Patch));
+
+  int i;
+  for (i = 0; i < *num_patches; ++i) {
+    if (ParseSha1(argv[i], (*patches)[i].sha1) != 0) {
+      printf("failed to parse sha1 \"%s\"\n", argv[i]);
+      return -1;
+    }
+    if (argv[i][SHA_DIGEST_SIZE*2] == '\0') {
+      (*patches)[i].patch_filename = NULL;
+    } else if (argv[i][SHA_DIGEST_SIZE*2] == ':') {
+      (*patches)[i].patch_filename = argv[i] + (SHA_DIGEST_SIZE*2+1);
+    } else {
+      printf("failed to parse filename \"%s\"\n", argv[i]);
+      return -1;
+    }
+  }
+
+  return 0;
+}
+
+// Search an array of Patch objects for one matching the given sha1.
+// Return the Patch object on success, or NULL if no match is found.
+const Patch* FindMatchingPatch(uint8_t* sha1, Patch* patches, int num_patches) {
+  int i;
+  for (i = 0; i < num_patches; ++i) {
+    if (memcmp(patches[i].sha1, sha1, SHA_DIGEST_SIZE) == 0) {
+      return patches+i;
+    }
+  }
+  return NULL;
+}
+
+// Returns 0 if the contents of the file (argv[2]) or the cached file
+// match any of the sha1's on the command line (argv[3:]).  Returns
+// nonzero otherwise.
+int CheckMode(int argc, char** argv) {
+  if (argc < 3) {
+    printf("no filename given\n");
+    return 2;
+  }
+
+  int num_patches;
+  Patch* patches;
+  if (ParseShaArgs(argc-3, argv+3, &patches, &num_patches) != 0) { return 1; }
+
+  FileContents file;
+  file.data = NULL;
+
+  // It's okay to specify no sha1s; the check will pass if the
+  // LoadFileContents is successful.  (Useful for reading MTD
+  // partitions, where the filename encodes the sha1s; no need to
+  // check them twice.)
+  if (LoadFileContents(argv[2], &file) != 0 ||
+      (num_patches > 0 &&
+       FindMatchingPatch(file.sha1, patches, num_patches) == NULL)) {
+    printf("file \"%s\" doesn't have any of expected "
+            "sha1 sums; checking cache\n", argv[2]);
+
+    free(file.data);
+
+    // If the source file is missing or corrupted, it might be because
+    // we were killed in the middle of patching it.  A copy of it
+    // should have been made in CACHE_TEMP_SOURCE.  If that file
+    // exists and matches the sha1 we're looking for, the check still
+    // passes.
+
+    if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
+      printf("failed to load cache file\n");
+      return 1;
+    }
+
+    if (FindMatchingPatch(file.sha1, patches, num_patches) == NULL) {
+      printf("cache bits don't match any sha1 for \"%s\"\n",
+              argv[2]);
+      return 1;
+    }
+  }
+
+  free(file.data);
+  return 0;
+}
+
+int ShowLicenses() {
+  ShowBSDiffLicense();
+  return 0;
+}
+
+ssize_t FileSink(unsigned char* data, ssize_t len, void* token) {
+  int fd = *(int *)token;
+  ssize_t done = 0;
+  ssize_t wrote;
+  while (done < (ssize_t) len) {
+    wrote = write(fd, data+done, len-done);
+    if (wrote <= 0) {
+      printf("error writing %d bytes: %s\n", (int)(len-done), strerror(errno));
+      return done;
+    }
+    done += wrote;
+  }
+  printf("wrote %d bytes to output\n", (int)done);
+  return done;
+}
+
+typedef struct {
+  unsigned char* buffer;
+  ssize_t size;
+  ssize_t pos;
+} MemorySinkInfo;
+
+ssize_t MemorySink(unsigned char* data, ssize_t len, void* token) {
+  MemorySinkInfo* msi = (MemorySinkInfo*)token;
+  if (msi->size - msi->pos < len) {
+    return -1;
+  }
+  memcpy(msi->buffer + msi->pos, data, len);
+  msi->pos += len;
+  return len;
+}
+
+// Return the amount of free space (in bytes) on the filesystem
+// containing filename.  filename must exist.  Return -1 on error.
+size_t FreeSpaceForFile(const char* filename) {
+  struct statfs sf;
+  if (statfs(filename, &sf) != 0) {
+    printf("failed to statfs %s: %s\n", filename, strerror(errno));
+    return -1;
+  }
+  return sf.f_bsize * sf.f_bfree;
+}
+
+// This program applies binary patches to files in a way that is safe
+// (the original file is not touched until we have the desired
+// replacement for it) and idempotent (it's okay to run this program
+// multiple times).
+//
+// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
+//   successfully.
+//
+// - otherwise, if the sha1 hash of <src-file> is <src-sha1>, applies the
+//   bsdiff <patch> to <src-file> to produce a new file (the type of patch
+//   is automatically detected from the file header).  If that new
+//   file has sha1 hash <tgt-sha1>, moves it to replace <tgt-file>, and
+//   exits successfully.  Note that if <src-file> and <tgt-file> are
+//   not the same, <src-file> is NOT deleted on success.  <tgt-file>
+//   may be the string "-" to mean "the same as src-file".
+//
+// - otherwise, or if any error is encountered, exits with non-zero
+//   status.
+//
+// <src-file> (or <file> in check mode) may refer to an MTD partition
+// to read the source data.  See the comments for the
+// LoadMTDContents() function above for the format of such a filename.
+//
+//
+// As you might guess from the arguments, this function used to be
+// main(); it was split out this way so applypatch could be built as a
+// static library and linked into other executables as well.  In the
+// future only the library form will exist; we will not need to build
+// this as a standalone executable.
+//
+// The arguments to this function are just the command-line of the
+// standalone executable:
+//
+// <src-file> <tgt-file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]
+//    to apply a patch.  Returns 0 on success, 1 on failure.
+//
+// "-c" <file> [<sha1> ...]
+//    to check a file's contents against zero or more sha1s.  Returns
+//    0 if it matches any of them, 1 if it doesn't.
+//
+// "-s" <bytes>
+//    returns 0 if enough free space is available on /cache; 1 if it
+//    does not.
+//
+// "-l"
+//    shows open-source license information and returns 0.
+//
+// This function returns 2 if the arguments are not understood (in the
+// standalone executable, this causes the usage message to be
+// printed).
+//
+// TODO: make the interface more sensible for use as a library.
+
+int applypatch(int argc, char** argv) {
+  if (argc < 2) {
+    return 2;
+  }
+
+  if (strncmp(argv[1], "-l", 3) == 0) {
+    return ShowLicenses();
+  }
+
+  if (strncmp(argv[1], "-c", 3) == 0) {
+    return CheckMode(argc, argv);
+  }
+
+  if (strncmp(argv[1], "-s", 3) == 0) {
+    if (argc != 3) {
+      return 2;
+    }
+    size_t bytes = strtol(argv[2], NULL, 10);
+    if (MakeFreeSpaceOnCache(bytes) < 0) {
+      printf("unable to make %ld bytes available on /cache\n", (long)bytes);
+      return 1;
+    } else {
+      return 0;
+    }
+  }
+
+  uint8_t target_sha1[SHA_DIGEST_SIZE];
+
+  const char* source_filename = argv[1];
+  const char* target_filename = argv[2];
+  if (target_filename[0] == '-' &&
+      target_filename[1] == '\0') {
+    target_filename = source_filename;
+  }
+
+  printf("\napplying patch to %s\n", source_filename);
+
+  if (ParseSha1(argv[3], target_sha1) != 0) {
+    printf("failed to parse tgt-sha1 \"%s\"\n", argv[3]);
+    return 1;
+  }
+
+  unsigned long target_size = strtoul(argv[4], NULL, 0);
+
+  int num_patches;
+  Patch* patches;
+  if (ParseShaArgs(argc-5, argv+5, &patches, &num_patches) < 0) { return 1; }
+
+  FileContents copy_file;
+  FileContents source_file;
+  const char* source_patch_filename = NULL;
+  const char* copy_patch_filename = NULL;
+  int made_copy = 0;
+
+  // We try to load the target file into the source_file object.
+  if (LoadFileContents(target_filename, &source_file) == 0) {
+    if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
+      // The early-exit case:  the patch was already applied, this file
+      // has the desired hash, nothing for us to do.
+      printf("\"%s\" is already target; no patch needed\n",
+              target_filename);
+      return 0;
+    }
+  }
+
+  if (source_file.data == NULL ||
+      (target_filename != source_filename &&
+       strcmp(target_filename, source_filename) != 0)) {
+    // Need to load the source file:  either we failed to load the
+    // target file, or we did but it's different from the source file.
+    free(source_file.data);
+    LoadFileContents(source_filename, &source_file);
+  }
+
+  if (source_file.data != NULL) {
+    const Patch* to_use =
+        FindMatchingPatch(source_file.sha1, patches, num_patches);
+    if (to_use != NULL) {
+      source_patch_filename = to_use->patch_filename;
+    }
+  }
+
+  if (source_patch_filename == NULL) {
+    free(source_file.data);
+    printf("source file is bad; trying copy\n");
+
+    if (LoadFileContents(CACHE_TEMP_SOURCE, &copy_file) < 0) {
+      // fail.
+      printf("failed to read copy file\n");
+      return 1;
+    }
+
+    const Patch* to_use =
+        FindMatchingPatch(copy_file.sha1, patches, num_patches);
+    if (to_use != NULL) {
+      copy_patch_filename = to_use->patch_filename;
+    }
+
+    if (copy_patch_filename == NULL) {
+      // fail.
+      printf("copy file doesn't match source SHA-1s either\n");
+      return 1;
+    }
+  }
+
+  int retry = 1;
+  SHA_CTX ctx;
+  int output;
+  MemorySinkInfo msi;
+  FileContents* source_to_use;
+  char* outname;
+
+  // assume that target_filename (eg "/system/app/Foo.apk") is located
+  // on the same filesystem as its top-level directory ("/system").
+  // We need something that exists for calling statfs().
+  char target_fs[strlen(target_filename)+1];
+  char* slash = strchr(target_filename+1, '/');
+  if (slash != NULL) {
+    int count = slash - target_filename;
+    strncpy(target_fs, target_filename, count);
+    target_fs[count] = '\0';
+  } else {
+    strcpy(target_fs, target_filename);
+  }
+
+  do {
+    // Is there enough room in the target filesystem to hold the patched
+    // file?
+
+    if (strncmp(target_filename, "MTD:", 4) == 0) {
+      // If the target is an MTD partition, we're actually going to
+      // write the output to /tmp and then copy it to the partition.
+      // statfs() always returns 0 blocks free for /tmp, so instead
+      // we'll just assume that /tmp has enough space to hold the file.
+
+      // We still write the original source to cache, in case the MTD
+      // write is interrupted.
+      if (MakeFreeSpaceOnCache(source_file.size) < 0) {
+        printf("not enough free space on /cache\n");
+        return 1;
+      }
+      if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
+        printf("failed to back up source file\n");
+        return 1;
+      }
+      made_copy = 1;
+      retry = 0;
+    } else {
+      int enough_space = 0;
+      if (retry > 0) {
+        size_t free_space = FreeSpaceForFile(target_fs);
+        int enough_space =
+          (free_space > (target_size * 3 / 2));  // 50% margin of error
+        printf("target %ld bytes; free space %ld bytes; retry %d; enough %d\n",
+               (long)target_size, (long)free_space, retry, enough_space);
+      }
+
+      if (!enough_space) {
+        retry = 0;
+      }
+
+      if (!enough_space && source_patch_filename != NULL) {
+        // Using the original source, but not enough free space.  First
+        // copy the source file to cache, then delete it from the original
+        // location.
+
+        if (strncmp(source_filename, "MTD:", 4) == 0) {
+          // It's impossible to free space on the target filesystem by
+          // deleting the source if the source is an MTD partition.  If
+          // we're ever in a state where we need to do this, fail.
+          printf("not enough free space for target but source is MTD\n");
+          return 1;
+        }
+
+        if (MakeFreeSpaceOnCache(source_file.size) < 0) {
+          printf("not enough free space on /cache\n");
+          return 1;
+        }
+
+        if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
+          printf("failed to back up source file\n");
+          return 1;
+        }
+        made_copy = 1;
+        unlink(source_filename);
+
+        size_t free_space = FreeSpaceForFile(target_fs);
+        printf("(now %ld bytes free for target)\n", (long)free_space);
+      }
+    }
+
+    const char* patch_filename;
+    if (source_patch_filename != NULL) {
+      source_to_use = &source_file;
+      patch_filename = source_patch_filename;
+    } else {
+      source_to_use = &copy_file;
+      patch_filename = copy_patch_filename;
+    }
+
+    SinkFn sink = NULL;
+    void* token = NULL;
+    output = -1;
+    outname = NULL;
+    if (strncmp(target_filename, "MTD:", 4) == 0) {
+      // We store the decoded output in memory.
+      msi.buffer = malloc(target_size);
+      if (msi.buffer == NULL) {
+        printf("failed to alloc %ld bytes for output\n",
+               (long)target_size);
+        return 1;
+      }
+      msi.pos = 0;
+      msi.size = target_size;
+      sink = MemorySink;
+      token = &msi;
+    } else {
+      // We write the decoded output to "<tgt-file>.patch".
+      outname = (char*)malloc(strlen(target_filename) + 10);
+      strcpy(outname, target_filename);
+      strcat(outname, ".patch");
+
+      output = open(outname, O_WRONLY | O_CREAT | O_TRUNC);
+      if (output < 0) {
+        printf("failed to open output file %s: %s\n",
+               outname, strerror(errno));
+        return 1;
+      }
+      sink = FileSink;
+      token = &output;
+    }
+
+#define MAX_HEADER_LENGTH 8
+    unsigned char header[MAX_HEADER_LENGTH];
+    FILE* patchf = fopen(patch_filename, "rb");
+    if (patchf == NULL) {
+      printf("failed to open patch file %s: %s\n",
+             patch_filename, strerror(errno));
+      return 1;
+    }
+    int header_bytes_read = fread(header, 1, MAX_HEADER_LENGTH, patchf);
+    fclose(patchf);
+
+    SHA_init(&ctx);
+
+    int result;
+
+    if (header_bytes_read >= 4 &&
+        header[0] == 0xd6 && header[1] == 0xc3 &&
+        header[2] == 0xc4 && header[3] == 0) {
+      // xdelta3 patches begin "VCD" (with the high bits set) followed
+      // by a zero byte (the version number).
+      printf("error:  xdelta3 patches no longer supported\n");
+      return 1;
+    } else if (header_bytes_read >= 8 &&
+               memcmp(header, "BSDIFF40", 8) == 0) {
+      result = ApplyBSDiffPatch(source_to_use->data, source_to_use->size,
+                                    patch_filename, 0, sink, token, &ctx);
+    } else if (header_bytes_read >= 8 &&
+               memcmp(header, "IMGDIFF", 7) == 0 &&
+               (header[7] == '1' || header[7] == '2')) {
+      result = ApplyImagePatch(source_to_use->data, source_to_use->size,
+                                   patch_filename, sink, token, &ctx);
+    } else {
+      printf("Unknown patch file format\n");
+      return 1;
+    }
+
+    if (output >= 0) {
+      fsync(output);
+      close(output);
+    }
+
+    if (result != 0) {
+      if (retry == 0) {
+        printf("applying patch failed\n");
+        return result != 0;
+      } else {
+        printf("applying patch failed; retrying\n");
+      }
+      if (outname != NULL) {
+        unlink(outname);
+      }
+    } else {
+      // succeeded; no need to retry
+      break;
+    }
+  } while (retry-- > 0);
+
+  const uint8_t* current_target_sha1 = SHA_final(&ctx);
+  if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_SIZE) != 0) {
+    printf("patch did not produce expected sha1\n");
+    return 1;
+  }
+
+  if (output < 0) {
+    // Copy the temp file to the MTD partition.
+    if (WriteToMTDPartition(msi.buffer, msi.pos, target_filename) != 0) {
+      printf("write of patched data to %s failed\n", target_filename);
+      return 1;
+    }
+    free(msi.buffer);
+  } else {
+    // Give the .patch file the same owner, group, and mode of the
+    // original source file.
+    if (chmod(outname, source_to_use->st.st_mode) != 0) {
+      printf("chmod of \"%s\" failed: %s\n", outname, strerror(errno));
+      return 1;
+    }
+    if (chown(outname, source_to_use->st.st_uid,
+              source_to_use->st.st_gid) != 0) {
+      printf("chown of \"%s\" failed: %s\n", outname, strerror(errno));
+      return 1;
+    }
+
+    // Finally, rename the .patch file to replace the target file.
+    if (rename(outname, target_filename) != 0) {
+      printf("rename of .patch to \"%s\" failed: %s\n",
+              target_filename, strerror(errno));
+      return 1;
+    }
+  }
+
+  // If this run of applypatch created the copy, and we're here, we
+  // can delete it.
+  if (made_copy) unlink(CACHE_TEMP_SOURCE);
+
+  // Success!
+  return 0;
+}
diff --git a/applypatch/applypatch.h b/applypatch/applypatch.h
new file mode 100644
index 0000000..3cb8021
--- /dev/null
+++ b/applypatch/applypatch.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _APPLYPATCH_H
+#define _APPLYPATCH_H
+
+#include <sys/stat.h>
+#include "mincrypt/sha.h"
+
+typedef struct _Patch {
+  uint8_t sha1[SHA_DIGEST_SIZE];
+  const char* patch_filename;
+} Patch;
+
+typedef struct _FileContents {
+  uint8_t sha1[SHA_DIGEST_SIZE];
+  unsigned char* data;
+  ssize_t size;
+  struct stat st;
+} FileContents;
+
+// When there isn't enough room on the target filesystem to hold the
+// patched version of the file, we copy the original here and delete
+// it to free up space.  If the expected source file doesn't exist, or
+// is corrupted, we look to see if this file contains the bits we want
+// and use it as the source instead.
+#define CACHE_TEMP_SOURCE "/cache/saved.file"
+
+typedef ssize_t (*SinkFn)(unsigned char*, ssize_t, void*);
+
+// applypatch.c
+size_t FreeSpaceForFile(const char* filename);
+int applypatch(int argc, char** argv);
+
+// Read a file into memory; store it and its associated metadata in
+// *file.  Return 0 on success.
+int LoadFileContents(const char* filename, FileContents* file);
+void FreeFileContents(FileContents* file);
+
+// bsdiff.c
+void ShowBSDiffLicense();
+int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
+                     const char* patch_filename, ssize_t offset,
+                     SinkFn sink, void* token, SHA_CTX* ctx);
+int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
+                        const char* patch_filename, ssize_t patch_offset,
+                        unsigned char** new_data, ssize_t* new_size);
+
+// imgpatch.c
+int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
+                    const char* patch_filename,
+                    SinkFn sink, void* token, SHA_CTX* ctx);
+
+// freecache.c
+int MakeFreeSpaceOnCache(size_t bytes_needed);
+
+#endif
diff --git a/applypatch/applypatch.sh b/applypatch/applypatch.sh
new file mode 100755
index 0000000..88f3025
--- /dev/null
+++ b/applypatch/applypatch.sh
@@ -0,0 +1,345 @@
+#!/bin/bash
+#
+# A test suite for applypatch.  Run in a client where you have done
+# envsetup, choosecombo, etc.
+#
+# DO NOT RUN THIS ON A DEVICE YOU CARE ABOUT.  It will mess up your
+# system partition.
+#
+#
+# TODO: find some way to get this run regularly along with the rest of
+# the tests.
+
+EMULATOR_PORT=5580
+DATA_DIR=$ANDROID_BUILD_TOP/build/tools/applypatch/testdata
+
+# This must be the filename that applypatch uses for its copies.
+CACHE_TEMP_SOURCE=/cache/saved.file
+
+# Put all binaries and files here.  We use /cache because it's a
+# temporary filesystem in the emulator; it's created fresh each time
+# the emulator starts.
+WORK_DIR=/system
+
+# partition that WORK_DIR is located on, without the leading slash
+WORK_FS=system
+
+# set to 0 to use a device instead
+USE_EMULATOR=1
+
+# ------------------------
+
+tmpdir=$(mktemp -d)
+
+if [ "$USE_EMULATOR" == 1 ]; then
+  emulator -wipe-data -noaudio -no-window -port $EMULATOR_PORT &
+  pid_emulator=$!
+  ADB="adb -s emulator-$EMULATOR_PORT "
+else
+  ADB="adb -d "
+fi
+
+echo "waiting to connect to device"
+$ADB wait-for-device
+echo "device is available"
+$ADB remount
+# free up enough space on the system partition for the test to run.
+$ADB shell rm -r /system/media
+
+# run a command on the device; exit with the exit status of the device
+# command.
+run_command() {
+  $ADB shell "$@" \; echo \$? | awk '{if (b) {print a}; a=$0; b=1} END {exit a}'
+}
+
+testname() {
+  echo
+  echo "$1"...
+  testname="$1"
+}
+
+fail() {
+  echo
+  echo FAIL: $testname
+  echo
+  [ "$open_pid" == "" ] || kill $open_pid
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
+  exit 1
+}
+
+sha1() {
+  sha1sum $1 | awk '{print $1}'
+}
+
+free_space() {
+  run_command df | awk "/$1/ {print gensub(/K/, \"\", \"g\", \$6)}"
+}
+
+cleanup() {
+  # not necessary if we're about to kill the emulator, but nice for
+  # running on real devices or already-running emulators.
+  testname "removing test files"
+  run_command rm $WORK_DIR/bloat.dat
+  run_command rm $WORK_DIR/old.file
+  run_command rm $WORK_DIR/patch.bsdiff
+  run_command rm $WORK_DIR/applypatch
+  run_command rm $CACHE_TEMP_SOURCE
+  run_command rm /cache/bloat*.dat
+
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
+
+  rm -rf $tmpdir
+}
+
+cleanup
+
+$ADB push $ANDROID_PRODUCT_OUT/system/bin/applypatch $WORK_DIR/applypatch
+
+BAD1_SHA1=$(printf "%040x" $RANDOM)
+BAD2_SHA1=$(printf "%040x" $RANDOM)
+OLD_SHA1=$(sha1 $DATA_DIR/old.file)
+NEW_SHA1=$(sha1 $DATA_DIR/new.file)
+NEW_SIZE=$(stat -c %s $DATA_DIR/new.file)
+
+# --------------- basic execution ----------------------
+
+testname "usage message"
+run_command $WORK_DIR/applypatch && fail
+
+testname "display license"
+run_command $WORK_DIR/applypatch -l | grep -q -i copyright || fail
+
+
+# --------------- check mode ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+
+testname "check mode single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# put some junk in the old file
+run_command dd if=/dev/urandom of=$WORK_DIR/old.file count=100 bs=1024 || fail
+
+testname "check mode cache (corrupted) single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode cache (corrupted) multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode cache (corrupted) failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+# remove the old file entirely
+run_command rm $WORK_DIR/old.file
+
+testname "check mode cache (missing) single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode cache (missing) multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode cache (missing) failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+
+# --------------- apply patch ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+# Check that the partition has enough space to apply the patch without
+# copying.  If it doesn't, we'll be testing the low-space condition
+# when we intend to test the not-low-space condition.
+testname "apply patches (with enough space)"
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS."
+if (( free_kb * 1024 < NEW_SIZE * 3 / 2 )); then
+  echo "Not enough space on /$WORK_FS to patch test file."
+  echo
+  echo "This doesn't mean that applypatch is necessarily broken;"
+  echo "just that /$WORK_FS doesn't have enough free space to"
+  echo "properly run this test."
+  exit 1
+fi
+
+testname "apply bsdiff patch"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+
+# --------------- apply patch in new location ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+# Check that the partition has enough space to apply the patch without
+# copying.  If it doesn't, we'll be testing the low-space condition
+# when we intend to test the not-low-space condition.
+testname "apply patch to new location (with enough space)"
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS."
+if (( free_kb * 1024 < NEW_SIZE * 3 / 2 )); then
+  echo "Not enough space on /$WORK_FS to patch test file."
+  echo
+  echo "This doesn't mean that applypatch is necessarily broken;"
+  echo "just that /$WORK_FS doesn't have enough free space to"
+  echo "properly run this test."
+  exit 1
+fi
+
+run_command rm $WORK_DIR/new.file
+run_command rm $CACHE_TEMP_SOURCE
+
+testname "apply bsdiff patch to new location"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch to new location"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# put some junk in the old file
+run_command dd if=/dev/urandom of=$WORK_DIR/old.file count=100 bs=1024 || fail
+
+testname "apply bsdiff patch to new location with corrupted source"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+# put some junk in the cache copy, too
+run_command dd if=/dev/urandom of=$CACHE_TEMP_SOURCE count=100 bs=1024 || fail
+
+run_command rm $WORK_DIR/new.file
+testname "apply bsdiff patch to new location with corrupted source and copy (no new file)"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo && fail
+
+# put some junk in the new file
+run_command dd if=/dev/urandom of=$WORK_DIR/new.file count=100 bs=1024 || fail
+
+testname "apply bsdiff patch to new location with corrupted source and copy (bad new file)"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo && fail
+
+# --------------- apply patch with low space on /system ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS; we'll soon fix that."
+echo run_command dd if=/dev/zero of=$WORK_DIR/bloat.dat count=$((free_kb-512)) bs=1024 || fail
+run_command dd if=/dev/zero of=$WORK_DIR/bloat.dat count=$((free_kb-512)) bs=1024 || fail
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS now."
+
+testname "apply bsdiff patch with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+# --------------- apply patch with low space on /system and /cache ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS"
+
+run_command mkdir /cache/subdir
+run_command 'echo > /cache/subdir/a.file'
+run_command 'echo > /cache/a.file'
+run_command mkdir /cache/recovery /cache/recovery/otatest
+run_command 'echo > /cache/recovery/otatest/b.file'
+run_command "echo > $CACHE_TEMP_SOURCE"
+free_kb=$(free_space cache)
+echo "${free_kb}kb free on /cache; we'll soon fix that."
+run_command dd if=/dev/zero of=/cache/bloat_small.dat count=128 bs=1024 || fail
+run_command dd if=/dev/zero of=/cache/bloat_large.dat count=$((free_kb-640)) bs=1024 || fail
+free_kb=$(free_space cache)
+echo "${free_kb}kb free on /cache now."
+
+testname "apply bsdiff patch with low space, full cache, can't delete enough"
+$ADB shell 'cat >> /cache/bloat_large.dat' & open_pid=$!
+echo "open_pid is $open_pid"
+
+# size check should fail even though it deletes some stuff
+run_command $WORK_DIR/applypatch -s $NEW_SIZE && fail
+run_command ls /cache/bloat_small.dat && fail          # was deleted
+run_command ls /cache/a.file && fail                   # was deleted
+run_command ls /cache/recovery/otatest/b.file && fail  # was deleted
+run_command ls /cache/bloat_large.dat || fail          # wasn't deleted because it was open
+run_command ls /cache/subdir/a.file || fail            # wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail              # wasn't deleted because it's the source file copy
+
+# should fail; not enough files can be deleted
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff && fail
+run_command ls /cache/bloat_large.dat || fail   # wasn't deleted because it was open
+run_command ls /cache/subdir/a.file || fail     # wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail       # wasn't deleted because it's the source file copy
+
+kill $open_pid   # /cache/bloat_large.dat is no longer open
+
+testname "apply bsdiff patch with low space, full cache, can delete enough"
+
+# should succeed after deleting /cache/bloat_large.dat
+run_command $WORK_DIR/applypatch -s $NEW_SIZE || fail
+run_command ls /cache/bloat_large.dat && fail   # was deleted
+run_command ls /cache/subdir/a.file || fail     # still wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail       # wasn't deleted because it's the source file copy
+
+# should succeed
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+run_command ls /cache/subdir/a.file || fail     # still wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE && fail       # was deleted because patching overwrote it, then deleted it
+
+# --------------- apply patch from cache ----------------------
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# put some junk in the old file
+run_command dd if=/dev/urandom of=$WORK_DIR/old.file count=100 bs=1024 || fail
+
+testname "apply bsdiff patch from cache (corrupted source) with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# remove the old file entirely
+run_command rm $WORK_DIR/old.file
+
+testname "apply bsdiff patch from cache (missing source) with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file - $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+
+# --------------- cleanup ----------------------
+
+cleanup
+
+echo
+echo PASS
+echo
+
diff --git a/applypatch/bsdiff.c b/applypatch/bsdiff.c
new file mode 100644
index 0000000..b6d342b
--- /dev/null
+++ b/applypatch/bsdiff.c
@@ -0,0 +1,410 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Most of this code comes from bsdiff.c from the bsdiff-4.3
+ * distribution, which is:
+ */
+
+/*-
+ * Copyright 2003-2005 Colin Percival
+ * All rights reserved
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted providing that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+
+#include <bzlib.h>
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define MIN(x,y) (((x)<(y)) ? (x) : (y))
+
+static void split(off_t *I,off_t *V,off_t start,off_t len,off_t h)
+{
+	off_t i,j,k,x,tmp,jj,kk;
+
+	if(len<16) {
+		for(k=start;k<start+len;k+=j) {
+			j=1;x=V[I[k]+h];
+			for(i=1;k+i<start+len;i++) {
+				if(V[I[k+i]+h]<x) {
+					x=V[I[k+i]+h];
+					j=0;
+				};
+				if(V[I[k+i]+h]==x) {
+					tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
+					j++;
+				};
+			};
+			for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
+			if(j==1) I[k]=-1;
+		};
+		return;
+	};
+
+	x=V[I[start+len/2]+h];
+	jj=0;kk=0;
+	for(i=start;i<start+len;i++) {
+		if(V[I[i]+h]<x) jj++;
+		if(V[I[i]+h]==x) kk++;
+	};
+	jj+=start;kk+=jj;
+
+	i=start;j=0;k=0;
+	while(i<jj) {
+		if(V[I[i]+h]<x) {
+			i++;
+		} else if(V[I[i]+h]==x) {
+			tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
+			j++;
+		} else {
+			tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
+			k++;
+		};
+	};
+
+	while(jj+j<kk) {
+		if(V[I[jj+j]+h]==x) {
+			j++;
+		} else {
+			tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
+			k++;
+		};
+	};
+
+	if(jj>start) split(I,V,start,jj-start,h);
+
+	for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
+	if(jj==kk-1) I[jj]=-1;
+
+	if(start+len>kk) split(I,V,kk,start+len-kk,h);
+}
+
+static void qsufsort(off_t *I,off_t *V,u_char *old,off_t oldsize)
+{
+	off_t buckets[256];
+	off_t i,h,len;
+
+	for(i=0;i<256;i++) buckets[i]=0;
+	for(i=0;i<oldsize;i++) buckets[old[i]]++;
+	for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
+	for(i=255;i>0;i--) buckets[i]=buckets[i-1];
+	buckets[0]=0;
+
+	for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
+	I[0]=oldsize;
+	for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
+	V[oldsize]=0;
+	for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
+	I[0]=-1;
+
+	for(h=1;I[0]!=-(oldsize+1);h+=h) {
+		len=0;
+		for(i=0;i<oldsize+1;) {
+			if(I[i]<0) {
+				len-=I[i];
+				i-=I[i];
+			} else {
+				if(len) I[i-len]=-len;
+				len=V[I[i]]+1-i;
+				split(I,V,i,len,h);
+				i+=len;
+				len=0;
+			};
+		};
+		if(len) I[i-len]=-len;
+	};
+
+	for(i=0;i<oldsize+1;i++) I[V[i]]=i;
+}
+
+static off_t matchlen(u_char *old,off_t oldsize,u_char *new,off_t newsize)
+{
+	off_t i;
+
+	for(i=0;(i<oldsize)&&(i<newsize);i++)
+		if(old[i]!=new[i]) break;
+
+	return i;
+}
+
+static off_t search(off_t *I,u_char *old,off_t oldsize,
+		u_char *new,off_t newsize,off_t st,off_t en,off_t *pos)
+{
+	off_t x,y;
+
+	if(en-st<2) {
+		x=matchlen(old+I[st],oldsize-I[st],new,newsize);
+		y=matchlen(old+I[en],oldsize-I[en],new,newsize);
+
+		if(x>y) {
+			*pos=I[st];
+			return x;
+		} else {
+			*pos=I[en];
+			return y;
+		}
+	};
+
+	x=st+(en-st)/2;
+	if(memcmp(old+I[x],new,MIN(oldsize-I[x],newsize))<0) {
+		return search(I,old,oldsize,new,newsize,x,en,pos);
+	} else {
+		return search(I,old,oldsize,new,newsize,st,x,pos);
+	};
+}
+
+static void offtout(off_t x,u_char *buf)
+{
+	off_t y;
+
+	if(x<0) y=-x; else y=x;
+
+		buf[0]=y%256;y-=buf[0];
+	y=y/256;buf[1]=y%256;y-=buf[1];
+	y=y/256;buf[2]=y%256;y-=buf[2];
+	y=y/256;buf[3]=y%256;y-=buf[3];
+	y=y/256;buf[4]=y%256;y-=buf[4];
+	y=y/256;buf[5]=y%256;y-=buf[5];
+	y=y/256;buf[6]=y%256;y-=buf[6];
+	y=y/256;buf[7]=y%256;
+
+	if(x<0) buf[7]|=0x80;
+}
+
+// This is main() from bsdiff.c, with the following changes:
+//
+//    - old, oldsize, new, newsize are arguments; we don't load this
+//      data from files.  old and new are owned by the caller; we
+//      don't free them at the end.
+//
+//    - the "I" block of memory is owned by the caller, who passes a
+//      pointer to *I, which can be NULL.  This way if we call
+//      bsdiff() multiple times with the same 'old' data, we only do
+//      the qsufsort() step the first time.
+//
+int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* new, off_t newsize,
+           const char* patch_filename)
+{
+	int fd;
+	off_t *I;
+	off_t scan,pos,len;
+	off_t lastscan,lastpos,lastoffset;
+	off_t oldscore,scsc;
+	off_t s,Sf,lenf,Sb,lenb;
+	off_t overlap,Ss,lens;
+	off_t i;
+	off_t dblen,eblen;
+	u_char *db,*eb;
+	u_char buf[8];
+	u_char header[32];
+	FILE * pf;
+	BZFILE * pfbz2;
+	int bz2err;
+
+        if (*IP == NULL) {
+            off_t* V;
+            *IP = malloc((oldsize+1) * sizeof(off_t));
+            V = malloc((oldsize+1) * sizeof(off_t));
+            qsufsort(*IP, V, old, oldsize);
+            free(V);
+        }
+        I = *IP;
+
+	if(((db=malloc(newsize+1))==NULL) ||
+		((eb=malloc(newsize+1))==NULL)) err(1,NULL);
+	dblen=0;
+	eblen=0;
+
+	/* Create the patch file */
+	if ((pf = fopen(patch_filename, "w")) == NULL)
+              err(1, "%s", patch_filename);
+
+	/* Header is
+		0	8	 "BSDIFF40"
+		8	8	length of bzip2ed ctrl block
+		16	8	length of bzip2ed diff block
+		24	8	length of new file */
+	/* File is
+		0	32	Header
+		32	??	Bzip2ed ctrl block
+		??	??	Bzip2ed diff block
+		??	??	Bzip2ed extra block */
+	memcpy(header,"BSDIFF40",8);
+	offtout(0, header + 8);
+	offtout(0, header + 16);
+	offtout(newsize, header + 24);
+	if (fwrite(header, 32, 1, pf) != 1)
+		err(1, "fwrite(%s)", patch_filename);
+
+	/* Compute the differences, writing ctrl as we go */
+	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+	scan=0;len=0;
+	lastscan=0;lastpos=0;lastoffset=0;
+	while(scan<newsize) {
+		oldscore=0;
+
+		for(scsc=scan+=len;scan<newsize;scan++) {
+			len=search(I,old,oldsize,new+scan,newsize-scan,
+					0,oldsize,&pos);
+
+			for(;scsc<scan+len;scsc++)
+			if((scsc+lastoffset<oldsize) &&
+				(old[scsc+lastoffset] == new[scsc]))
+				oldscore++;
+
+			if(((len==oldscore) && (len!=0)) ||
+				(len>oldscore+8)) break;
+
+			if((scan+lastoffset<oldsize) &&
+				(old[scan+lastoffset] == new[scan]))
+				oldscore--;
+		};
+
+		if((len!=oldscore) || (scan==newsize)) {
+			s=0;Sf=0;lenf=0;
+			for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
+				if(old[lastpos+i]==new[lastscan+i]) s++;
+				i++;
+				if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
+			};
+
+			lenb=0;
+			if(scan<newsize) {
+				s=0;Sb=0;
+				for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
+					if(old[pos-i]==new[scan-i]) s++;
+					if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
+				};
+			};
+
+			if(lastscan+lenf>scan-lenb) {
+				overlap=(lastscan+lenf)-(scan-lenb);
+				s=0;Ss=0;lens=0;
+				for(i=0;i<overlap;i++) {
+					if(new[lastscan+lenf-overlap+i]==
+					   old[lastpos+lenf-overlap+i]) s++;
+					if(new[scan-lenb+i]==
+					   old[pos-lenb+i]) s--;
+					if(s>Ss) { Ss=s; lens=i+1; };
+				};
+
+				lenf+=lens-overlap;
+				lenb-=lens;
+			};
+
+			for(i=0;i<lenf;i++)
+				db[dblen+i]=new[lastscan+i]-old[lastpos+i];
+			for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
+				eb[eblen+i]=new[lastscan+lenf+i];
+
+			dblen+=lenf;
+			eblen+=(scan-lenb)-(lastscan+lenf);
+
+			offtout(lenf,buf);
+			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+			if (bz2err != BZ_OK)
+				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+			offtout((scan-lenb)-(lastscan+lenf),buf);
+			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+			if (bz2err != BZ_OK)
+				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+			offtout((pos-lenb)-(lastpos+lenf),buf);
+			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+			if (bz2err != BZ_OK)
+				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+			lastscan=scan-lenb;
+			lastpos=pos-lenb;
+			lastoffset=pos-scan;
+		};
+	};
+	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+	if (bz2err != BZ_OK)
+		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+	/* Compute size of compressed ctrl data */
+	if ((len = ftello(pf)) == -1)
+		err(1, "ftello");
+	offtout(len-32, header + 8);
+
+	/* Write compressed diff data */
+	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+	BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
+	if (bz2err != BZ_OK)
+		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+	if (bz2err != BZ_OK)
+		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+	/* Compute size of compressed diff data */
+	if ((newsize = ftello(pf)) == -1)
+		err(1, "ftello");
+	offtout(newsize - len, header + 16);
+
+	/* Write compressed extra data */
+	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+	BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
+	if (bz2err != BZ_OK)
+		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+	if (bz2err != BZ_OK)
+		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+	/* Seek to the beginning, write the header, and close the file */
+	if (fseeko(pf, 0, SEEK_SET))
+		err(1, "fseeko");
+	if (fwrite(header, 32, 1, pf) != 1)
+		err(1, "fwrite(%s)", patch_filename);
+	if (fclose(pf))
+		err(1, "fclose");
+
+	/* Free the memory we used */
+	free(db);
+	free(eb);
+
+	return 0;
+}
diff --git a/applypatch/bspatch.c b/applypatch/bspatch.c
new file mode 100644
index 0000000..d5cd617
--- /dev/null
+++ b/applypatch/bspatch.c
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// This file is a nearly line-for-line copy of bspatch.c from the
+// bsdiff-4.3 distribution; the primary differences being how the
+// input and output data are read and the error handling.  Running
+// applypatch with the -l option will display the bsdiff license
+// notice.
+
+#include <stdio.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <bzlib.h>
+
+#include "mincrypt/sha.h"
+#include "applypatch.h"
+
+void ShowBSDiffLicense() {
+  puts("The bsdiff library used herein is:\n"
+       "\n"
+       "Copyright 2003-2005 Colin Percival\n"
+       "All rights reserved\n"
+       "\n"
+       "Redistribution and use in source and binary forms, with or without\n"
+       "modification, are permitted providing that the following conditions\n"
+       "are met:\n"
+       "1. Redistributions of source code must retain the above copyright\n"
+       "   notice, this list of conditions and the following disclaimer.\n"
+       "2. Redistributions in binary form must reproduce the above copyright\n"
+       "   notice, this list of conditions and the following disclaimer in the\n"
+       "   documentation and/or other materials provided with the distribution.\n"
+       "\n"
+       "THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR\n"
+       "IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\n"
+       "WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE\n"
+       "ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY\n"
+       "DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL\n"
+       "DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS\n"
+       "OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)\n"
+       "HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,\n"
+       "STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING\n"
+       "IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE\n"
+       "POSSIBILITY OF SUCH DAMAGE.\n"
+       "\n------------------\n\n"
+       "This program uses Julian R Seward's \"libbzip2\" library, available\n"
+       "from http://www.bzip.org/.\n"
+       );
+}
+
+static off_t offtin(u_char *buf)
+{
+  off_t y;
+
+  y=buf[7]&0x7F;
+  y=y*256;y+=buf[6];
+  y=y*256;y+=buf[5];
+  y=y*256;y+=buf[4];
+  y=y*256;y+=buf[3];
+  y=y*256;y+=buf[2];
+  y=y*256;y+=buf[1];
+  y=y*256;y+=buf[0];
+
+  if(buf[7]&0x80) y=-y;
+
+  return y;
+}
+
+
+int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
+                     const char* patch_filename, ssize_t patch_offset,
+                     SinkFn sink, void* token, SHA_CTX* ctx) {
+
+  unsigned char* new_data;
+  ssize_t new_size;
+  if (ApplyBSDiffPatchMem(old_data, old_size, patch_filename, patch_offset,
+                          &new_data, &new_size) != 0) {
+    return -1;
+  }
+
+  if (sink(new_data, new_size, token) < new_size) {
+    fprintf(stderr, "short write of output: %d (%s)\n", errno, strerror(errno));
+    return 1;
+  }
+  if (ctx) {
+    SHA_update(ctx, new_data, new_size);
+  }
+  free(new_data);
+
+  return 0;
+}
+
+int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
+                        const char* patch_filename, ssize_t patch_offset,
+                        unsigned char** new_data, ssize_t* new_size) {
+
+  FILE* f;
+  if ((f = fopen(patch_filename, "rb")) == NULL) {
+    fprintf(stderr, "failed to open patch file\n");
+    return 1;
+  }
+
+  // File format:
+  //   0       8       "BSDIFF40"
+  //   8       8       X
+  //   16      8       Y
+  //   24      8       sizeof(newfile)
+  //   32      X       bzip2(control block)
+  //   32+X    Y       bzip2(diff block)
+  //   32+X+Y  ???     bzip2(extra block)
+  // with control block a set of triples (x,y,z) meaning "add x bytes
+  // from oldfile to x bytes from the diff block; copy y bytes from the
+  // extra block; seek forwards in oldfile by z bytes".
+
+  fseek(f, patch_offset, SEEK_SET);
+
+  unsigned char header[32];
+  if (fread(header, 1, 32, f) < 32) {
+    fprintf(stderr, "failed to read patch file header\n");
+    return 1;
+  }
+
+  if (memcmp(header, "BSDIFF40", 8) != 0) {
+    fprintf(stderr, "corrupt bsdiff patch file header (magic number)\n");
+    return 1;
+  }
+
+  ssize_t ctrl_len, data_len;
+  ctrl_len = offtin(header+8);
+  data_len = offtin(header+16);
+  *new_size = offtin(header+24);
+
+  if (ctrl_len < 0 || data_len < 0 || *new_size < 0) {
+    fprintf(stderr, "corrupt patch file header (data lengths)\n");
+    return 1;
+  }
+
+  fclose(f);
+
+  int bzerr;
+
+#define OPEN_AT(f, bzf, offset)                                          \
+  FILE* f;                                                               \
+  BZFILE* bzf;                                                           \
+  if ((f = fopen(patch_filename, "rb")) == NULL) {                       \
+    fprintf(stderr, "failed to open patch file\n");                      \
+    return 1;                                                            \
+  }                                                                      \
+  if (fseeko(f, offset+patch_offset, SEEK_SET)) {                        \
+    fprintf(stderr, "failed to seek in patch file\n");                   \
+    return 1;                                                            \
+  }                                                                      \
+  if ((bzf = BZ2_bzReadOpen(&bzerr, f, 0, 0, NULL, 0)) == NULL) {        \
+    fprintf(stderr, "failed to bzReadOpen in patch file (%d)\n", bzerr); \
+    return 1;                                                            \
+  }
+
+  OPEN_AT(cpf, cpfbz2, 32);
+  OPEN_AT(dpf, dpfbz2, 32+ctrl_len);
+  OPEN_AT(epf, epfbz2, 32+ctrl_len+data_len);
+
+#undef OPEN_AT
+
+  *new_data = malloc(*new_size);
+  if (*new_data == NULL) {
+    fprintf(stderr, "failed to allocate %d bytes of memory for output file\n",
+            (int)*new_size);
+    return 1;
+  }
+
+  off_t oldpos = 0, newpos = 0;
+  off_t ctrl[3];
+  off_t len_read;
+  int i;
+  unsigned char buf[8];
+  while (newpos < *new_size) {
+    // Read control data
+    for (i = 0; i < 3; ++i) {
+      len_read = BZ2_bzRead(&bzerr, cpfbz2, buf, 8);
+      if (len_read < 8 || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
+        fprintf(stderr, "corrupt patch (read control)\n");
+        return 1;
+      }
+      ctrl[i] = offtin(buf);
+    }
+
+    // Sanity check
+    if (newpos + ctrl[0] > *new_size) {
+      fprintf(stderr, "corrupt patch (new file overrun)\n");
+      return 1;
+    }
+
+    // Read diff string
+    len_read = BZ2_bzRead(&bzerr, dpfbz2, *new_data + newpos, ctrl[0]);
+    if (len_read < ctrl[0] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
+      fprintf(stderr, "corrupt patch (read diff)\n");
+      return 1;
+    }
+
+    // Add old data to diff string
+    for (i = 0; i < ctrl[0]; ++i) {
+      if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
+        (*new_data)[newpos+i] += old_data[oldpos+i];
+      }
+    }
+
+    // Adjust pointers
+    newpos += ctrl[0];
+    oldpos += ctrl[0];
+
+    // Sanity check
+    if (newpos + ctrl[1] > *new_size) {
+      fprintf(stderr, "corrupt patch (new file overrun)\n");
+      return 1;
+    }
+
+    // Read extra string
+    len_read = BZ2_bzRead(&bzerr, epfbz2, *new_data + newpos, ctrl[1]);
+    if (len_read < ctrl[1] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
+      fprintf(stderr, "corrupt patch (read extra)\n");
+      return 1;
+    }
+
+    // Adjust pointers
+    newpos += ctrl[1];
+    oldpos += ctrl[2];
+  }
+
+  BZ2_bzReadClose(&bzerr, cpfbz2);
+  BZ2_bzReadClose(&bzerr, dpfbz2);
+  BZ2_bzReadClose(&bzerr, epfbz2);
+  fclose(cpf);
+  fclose(dpf);
+  fclose(epf);
+
+  return 0;
+}
diff --git a/applypatch/freecache.c b/applypatch/freecache.c
new file mode 100644
index 0000000..9827fda
--- /dev/null
+++ b/applypatch/freecache.c
@@ -0,0 +1,172 @@
+#include <errno.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <ctype.h>
+
+#include "applypatch.h"
+
+static int EliminateOpenFiles(char** files, int file_count) {
+  DIR* d;
+  struct dirent* de;
+  d = opendir("/proc");
+  if (d == NULL) {
+    printf("error opening /proc: %s\n", strerror(errno));
+    return -1;
+  }
+  while ((de = readdir(d)) != 0) {
+    int i;
+    for (i = 0; de->d_name[i] != '\0' && isdigit(de->d_name[i]); ++i);
+    if (de->d_name[i]) continue;
+
+    // de->d_name[i] is numeric
+
+    char path[FILENAME_MAX];
+    strcpy(path, "/proc/");
+    strcat(path, de->d_name);
+    strcat(path, "/fd/");
+
+    DIR* fdd;
+    struct dirent* fdde;
+    fdd = opendir(path);
+    if (fdd == NULL) {
+      printf("error opening %s: %s\n", path, strerror(errno));
+      continue;
+    }
+    while ((fdde = readdir(fdd)) != 0) {
+      char fd_path[FILENAME_MAX];
+      char link[FILENAME_MAX];
+      strcpy(fd_path, path);
+      strcat(fd_path, fdde->d_name);
+
+      int count;
+      count = readlink(fd_path, link, sizeof(link)-1);
+      if (count >= 0) {
+        link[count] = '\0';
+
+        // This is inefficient, but it should only matter if there are
+        // lots of files in /cache, and lots of them are open (neither
+        // of which should be true, especially in recovery).
+        if (strncmp(link, "/cache/", 7) == 0) {
+          int j;
+          for (j = 0; j < file_count; ++j) {
+            if (files[j] && strcmp(files[j], link) == 0) {
+              printf("%s is open by %s\n", link, de->d_name);
+              free(files[j]);
+              files[j] = NULL;
+            }
+          }
+        }
+      }
+    }
+    closedir(fdd);
+  }
+  closedir(d);
+
+  return 0;
+}
+
+int FindExpendableFiles(char*** names, int* entries) {
+  DIR* d;
+  struct dirent* de;
+  int size = 32;
+  *entries = 0;
+  *names = malloc(size * sizeof(char*));
+
+  char path[FILENAME_MAX];
+
+  // We're allowed to delete unopened regular files in any of these
+  // directories.
+  const char* dirs[2] = {"/cache", "/cache/recovery/otatest"};
+
+  unsigned int i;
+  for (i = 0; i < sizeof(dirs)/sizeof(dirs[0]); ++i) {
+    d = opendir(dirs[i]);
+    if (d == NULL) {
+      printf("error opening %s: %s\n", dirs[i], strerror(errno));
+      continue;
+    }
+
+    // Look for regular files in the directory (not in any subdirectories).
+    while ((de = readdir(d)) != 0) {
+      strcpy(path, dirs[i]);
+      strcat(path, "/");
+      strcat(path, de->d_name);
+
+      // We can't delete CACHE_TEMP_SOURCE; if it's there we might have
+      // restarted during installation and could be depending on it to
+      // be there.
+      if (strcmp(path, CACHE_TEMP_SOURCE) == 0) continue;
+
+      struct stat st;
+      if (stat(path, &st) == 0 && S_ISREG(st.st_mode)) {
+        if (*entries >= size) {
+          size *= 2;
+          *names = realloc(*names, size * sizeof(char*));
+        }
+        (*names)[(*entries)++] = strdup(path);
+      }
+    }
+
+    closedir(d);
+  }
+
+  printf("%d regular files in deletable directories\n", *entries);
+
+  if (EliminateOpenFiles(*names, *entries) < 0) {
+    return -1;
+  }
+
+  return 0;
+}
+
+int MakeFreeSpaceOnCache(size_t bytes_needed) {
+  size_t free_now = FreeSpaceForFile("/cache");
+  printf("%ld bytes free on /cache (%ld needed)\n",
+         (long)free_now, (long)bytes_needed);
+
+  if (free_now >= bytes_needed) {
+    return 0;
+  }
+
+  char** names;
+  int entries;
+
+  if (FindExpendableFiles(&names, &entries) < 0) {
+    return -1;
+  }
+
+  if (entries == 0) {
+    // nothing we can delete to free up space!
+    printf("no files can be deleted to free space on /cache\n");
+    return -1;
+  }
+
+  // We could try to be smarter about which files to delete:  the
+  // biggest ones?  the smallest ones that will free up enough space?
+  // the oldest?  the newest?
+  //
+  // Instead, we'll be dumb.
+
+  int i;
+  for (i = 0; i < entries && free_now < bytes_needed; ++i) {
+    if (names[i]) {
+      unlink(names[i]);
+      free_now = FreeSpaceForFile("/cache");
+      printf("deleted %s; now %ld bytes free\n", names[i], (long)free_now);
+      free(names[i]);
+    }
+  }
+
+  for (; i < entries; ++i) {
+    free(names[i]);
+  }
+  free(names);
+
+  return (free_now >= bytes_needed) ? 0 : -1;
+}
diff --git a/applypatch/imgdiff.c b/applypatch/imgdiff.c
new file mode 100644
index 0000000..6b9ebee
--- /dev/null
+++ b/applypatch/imgdiff.c
@@ -0,0 +1,1010 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * This program constructs binary patches for images -- such as boot.img
+ * and recovery.img -- that consist primarily of large chunks of gzipped
+ * data interspersed with uncompressed data.  Doing a naive bsdiff of
+ * these files is not useful because small changes in the data lead to
+ * large changes in the compressed bitstream; bsdiff patches of gzipped
+ * data are typically as large as the data itself.
+ *
+ * To patch these usefully, we break the source and target images up into
+ * chunks of two types: "normal" and "gzip".  Normal chunks are simply
+ * patched using a plain bsdiff.  Gzip chunks are first expanded, then a
+ * bsdiff is applied to the uncompressed data, then the patched data is
+ * gzipped using the same encoder parameters.  Patched chunks are
+ * concatenated together to create the output file; the output image
+ * should be *exactly* the same series of bytes as the target image used
+ * originally to generate the patch.
+ *
+ * To work well with this tool, the gzipped sections of the target
+ * image must have been generated using the same deflate encoder that
+ * is available in applypatch, namely, the one in the zlib library.
+ * In practice this means that images should be compressed using the
+ * "minigzip" tool included in the zlib distribution, not the GNU gzip
+ * program.
+ *
+ * An "imgdiff" patch consists of a header describing the chunk structure
+ * of the file and any encoding parameters needed for the gzipped
+ * chunks, followed by N bsdiff patches, one per chunk.
+ *
+ * For a diff to be generated, the source and target images must have the
+ * same "chunk" structure: that is, the same number of gzipped and normal
+ * chunks in the same order.  Android boot and recovery images currently
+ * consist of five chunks:  a small normal header, a gzipped kernel, a
+ * small normal section, a gzipped ramdisk, and finally a small normal
+ * footer.
+ *
+ * Caveats:  we locate gzipped sections within the source and target
+ * images by searching for the byte sequence 1f8b0800:  1f8b is the gzip
+ * magic number; 08 specifies the "deflate" encoding [the only encoding
+ * supported by the gzip standard]; and 00 is the flags byte.  We do not
+ * currently support any extra header fields (which would be indicated by
+ * a nonzero flags byte).  We also don't handle the case when that byte
+ * sequence appears spuriously in the file.  (Note that it would have to
+ * occur spuriously within a normal chunk to be a problem.)
+ *
+ *
+ * The imgdiff patch header looks like this:
+ *
+ *    "IMGDIFF1"                  (8)   [magic number and version]
+ *    chunk count                 (4)
+ *    for each chunk:
+ *        chunk type              (4)   [CHUNK_{NORMAL, GZIP, DEFLATE, RAW}]
+ *        if chunk type == CHUNK_NORMAL:
+ *           source start         (8)
+ *           source len           (8)
+ *           bsdiff patch offset  (8)   [from start of patch file]
+ *        if chunk type == CHUNK_GZIP:      (version 1 only)
+ *           source start         (8)
+ *           source len           (8)
+ *           bsdiff patch offset  (8)   [from start of patch file]
+ *           source expanded len  (8)   [size of uncompressed source]
+ *           target expected len  (8)   [size of uncompressed target]
+ *           gzip level           (4)
+ *                method          (4)
+ *                windowBits      (4)
+ *                memLevel        (4)
+ *                strategy        (4)
+ *           gzip header len      (4)
+ *           gzip header          (gzip header len)
+ *           gzip footer          (8)
+ *        if chunk type == CHUNK_DEFLATE:   (version 2 only)
+ *           source start         (8)
+ *           source len           (8)
+ *           bsdiff patch offset  (8)   [from start of patch file]
+ *           source expanded len  (8)   [size of uncompressed source]
+ *           target expected len  (8)   [size of uncompressed target]
+ *           gzip level           (4)
+ *                method          (4)
+ *                windowBits      (4)
+ *                memLevel        (4)
+ *                strategy        (4)
+ *        if chunk type == RAW:             (version 2 only)
+ *           target len           (4)
+ *           data                 (target len)
+ *
+ * All integers are little-endian.  "source start" and "source len"
+ * specify the section of the input image that comprises this chunk,
+ * including the gzip header and footer for gzip chunks.  "source
+ * expanded len" is the size of the uncompressed source data.  "target
+ * expected len" is the size of the uncompressed data after applying
+ * the bsdiff patch.  The next five parameters specify the zlib
+ * parameters to be used when compressing the patched data, and the
+ * next three specify the header and footer to be wrapped around the
+ * compressed data to create the output chunk (so that header contents
+ * like the timestamp are recreated exactly).
+ *
+ * After the header there are 'chunk count' bsdiff patches; the offset
+ * of each from the beginning of the file is specified in the header.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "zlib.h"
+#include "imgdiff.h"
+#include "utils.h"
+
+typedef struct {
+  int type;             // CHUNK_NORMAL, CHUNK_DEFLATE
+  size_t start;         // offset of chunk in original image file
+
+  size_t len;
+  unsigned char* data;  // data to be patched (uncompressed, for deflate chunks)
+
+  size_t source_start;
+  size_t source_len;
+
+  off_t* I;             // used by bsdiff
+
+  // --- for CHUNK_DEFLATE chunks only: ---
+
+  // original (compressed) deflate data
+  size_t deflate_len;
+  unsigned char* deflate_data;
+
+  char* filename;       // used for zip entries
+
+  // deflate encoder parameters
+  int level, method, windowBits, memLevel, strategy;
+
+  size_t source_uncompressed_len;
+} ImageChunk;
+
+typedef struct {
+  int data_offset;
+  int deflate_len;
+  int uncomp_len;
+  char* filename;
+} ZipFileEntry;
+
+static int fileentry_compare(const void* a, const void* b) {
+  int ao = ((ZipFileEntry*)a)->data_offset;
+  int bo = ((ZipFileEntry*)b)->data_offset;
+  if (ao < bo) {
+    return -1;
+  } else if (ao > bo) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+// from bsdiff.c
+int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* new, off_t newsize,
+           const char* patch_filename);
+
+unsigned char* ReadZip(const char* filename,
+                       int* num_chunks, ImageChunk** chunks,
+                       int include_pseudo_chunk) {
+  struct stat st;
+  if (stat(filename, &st) != 0) {
+    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+    return NULL;
+  }
+
+  unsigned char* img = malloc(st.st_size);
+  FILE* f = fopen(filename, "rb");
+  if (fread(img, 1, st.st_size, f) != st.st_size) {
+    printf("failed to read \"%s\" %s\n", filename, strerror(errno));
+    fclose(f);
+    return NULL;
+  }
+  fclose(f);
+
+  // look for the end-of-central-directory record.
+
+  int i;
+  for (i = st.st_size-20; i >= 0 && i > st.st_size - 65600; --i) {
+    if (img[i] == 0x50 && img[i+1] == 0x4b &&
+        img[i+2] == 0x05 && img[i+3] == 0x06) {
+      break;
+    }
+  }
+  // double-check: this archive consists of a single "disk"
+  if (!(img[i+4] == 0 && img[i+5] == 0 && img[i+6] == 0 && img[i+7] == 0)) {
+    printf("can't process multi-disk archive\n");
+    return NULL;
+  }
+
+  int cdcount = Read2(img+i+8);
+  int cdoffset = Read4(img+i+16);
+
+  ZipFileEntry* temp_entries = malloc(cdcount * sizeof(ZipFileEntry));
+  int entrycount = 0;
+
+  unsigned char* cd = img+cdoffset;
+  for (i = 0; i < cdcount; ++i) {
+    if (!(cd[0] == 0x50 && cd[1] == 0x4b && cd[2] == 0x01 && cd[3] == 0x02)) {
+      printf("bad central directory entry %d\n", i);
+      return NULL;
+    }
+
+    int clen = Read4(cd+20);   // compressed len
+    int ulen = Read4(cd+24);   // uncompressed len
+    int nlen = Read2(cd+28);   // filename len
+    int xlen = Read2(cd+30);   // extra field len
+    int mlen = Read2(cd+32);   // file comment len
+    int hoffset = Read4(cd+42);   // local header offset
+
+    char* filename = malloc(nlen+1);
+    memcpy(filename, cd+46, nlen);
+    filename[nlen] = '\0';
+
+    int method = Read2(cd+10);
+
+    cd += 46 + nlen + xlen + mlen;
+
+    if (method != 8) {  // 8 == deflate
+      free(filename);
+      continue;
+    }
+
+    unsigned char* lh = img + hoffset;
+
+    if (!(lh[0] == 0x50 && lh[1] == 0x4b && lh[2] == 0x03 && lh[3] == 0x04)) {
+      printf("bad local file header entry %d\n", i);
+      return NULL;
+    }
+
+    if (Read2(lh+26) != nlen || memcmp(lh+30, filename, nlen) != 0) {
+      printf("central dir filename doesn't match local header\n");
+      return NULL;
+    }
+
+    xlen = Read2(lh+28);   // extra field len; might be different from CD entry?
+
+    temp_entries[entrycount].data_offset = hoffset+30+nlen+xlen;
+    temp_entries[entrycount].deflate_len = clen;
+    temp_entries[entrycount].uncomp_len = ulen;
+    temp_entries[entrycount].filename = filename;
+    ++entrycount;
+  }
+
+  qsort(temp_entries, entrycount, sizeof(ZipFileEntry), fileentry_compare);
+
+#if 0
+  printf("found %d deflated entries\n", entrycount);
+  for (i = 0; i < entrycount; ++i) {
+    printf("off %10d  len %10d unlen %10d   %p %s\n",
+           temp_entries[i].data_offset,
+           temp_entries[i].deflate_len,
+           temp_entries[i].uncomp_len,
+           temp_entries[i].filename,
+           temp_entries[i].filename);
+  }
+#endif
+
+  *num_chunks = 0;
+  *chunks = malloc((entrycount*2+2) * sizeof(ImageChunk));
+  ImageChunk* curr = *chunks;
+
+  if (include_pseudo_chunk) {
+    curr->type = CHUNK_NORMAL;
+    curr->start = 0;
+    curr->len = st.st_size;
+    curr->data = img;
+    curr->filename = NULL;
+    curr->I = NULL;
+    ++curr;
+    ++*num_chunks;
+  }
+
+  int pos = 0;
+  int nextentry = 0;
+
+  while (pos < st.st_size) {
+    if (nextentry < entrycount && pos == temp_entries[nextentry].data_offset) {
+      curr->type = CHUNK_DEFLATE;
+      curr->start = pos;
+      curr->deflate_len = temp_entries[nextentry].deflate_len;
+      curr->deflate_data = img + pos;
+      curr->filename = temp_entries[nextentry].filename;
+      curr->I = NULL;
+
+      curr->len = temp_entries[nextentry].uncomp_len;
+      curr->data = malloc(curr->len);
+
+      z_stream strm;
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = curr->deflate_len;
+      strm.next_in = curr->deflate_data;
+
+      // -15 means we are decoding a 'raw' deflate stream; zlib will
+      // not expect zlib headers.
+      int ret = inflateInit2(&strm, -15);
+
+      strm.avail_out = curr->len;
+      strm.next_out = curr->data;
+      ret = inflate(&strm, Z_NO_FLUSH);
+      if (ret != Z_STREAM_END) {
+        printf("failed to inflate \"%s\"; %d\n", curr->filename, ret);
+        return NULL;
+      }
+
+      inflateEnd(&strm);
+
+      pos += curr->deflate_len;
+      ++nextentry;
+      ++*num_chunks;
+      ++curr;
+      continue;
+    }
+
+    // use a normal chunk to take all the data up to the start of the
+    // next deflate section.
+
+    curr->type = CHUNK_NORMAL;
+    curr->start = pos;
+    if (nextentry < entrycount) {
+      curr->len = temp_entries[nextentry].data_offset - pos;
+    } else {
+      curr->len = st.st_size - pos;
+    }
+    curr->data = img + pos;
+    curr->filename = NULL;
+    curr->I = NULL;
+    pos += curr->len;
+
+    ++*num_chunks;
+    ++curr;
+  }
+
+  free(temp_entries);
+  return img;
+}
+
+/*
+ * Read the given file and break it up into chunks, putting the number
+ * of chunks and their info in *num_chunks and **chunks,
+ * respectively.  Returns a malloc'd block of memory containing the
+ * contents of the file; various pointers in the output chunk array
+ * will point into this block of memory.  The caller should free the
+ * return value when done with all the chunks.  Returns NULL on
+ * failure.
+ */
+unsigned char* ReadImage(const char* filename,
+                         int* num_chunks, ImageChunk** chunks) {
+  struct stat st;
+  if (stat(filename, &st) != 0) {
+    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+    return NULL;
+  }
+
+  unsigned char* img = malloc(st.st_size + 4);
+  FILE* f = fopen(filename, "rb");
+  if (fread(img, 1, st.st_size, f) != st.st_size) {
+    printf("failed to read \"%s\" %s\n", filename, strerror(errno));
+    fclose(f);
+    return NULL;
+  }
+  fclose(f);
+
+  // append 4 zero bytes to the data so we can always search for the
+  // four-byte string 1f8b0800 starting at any point in the actual
+  // file data, without special-casing the end of the data.
+  memset(img+st.st_size, 0, 4);
+
+  size_t pos = 0;
+
+  *num_chunks = 0;
+  *chunks = NULL;
+
+  while (pos < st.st_size) {
+    unsigned char* p = img+pos;
+
+    if (st.st_size - pos >= 4 &&
+        p[0] == 0x1f && p[1] == 0x8b &&
+        p[2] == 0x08 &&    // deflate compression
+        p[3] == 0x00) {    // no header flags
+      // 'pos' is the offset of the start of a gzip chunk.
+
+      *num_chunks += 3;
+      *chunks = realloc(*chunks, *num_chunks * sizeof(ImageChunk));
+      ImageChunk* curr = *chunks + (*num_chunks-3);
+
+      // create a normal chunk for the header.
+      curr->start = pos;
+      curr->type = CHUNK_NORMAL;
+      curr->len = GZIP_HEADER_LEN;
+      curr->data = p;
+      curr->I = NULL;
+
+      pos += curr->len;
+      p += curr->len;
+      ++curr;
+
+      curr->type = CHUNK_DEFLATE;
+      curr->filename = NULL;
+      curr->I = NULL;
+
+      // We must decompress this chunk in order to discover where it
+      // ends, and so we can put the uncompressed data and its length
+      // into curr->data and curr->len.
+
+      size_t allocated = 32768;
+      curr->len = 0;
+      curr->data = malloc(allocated);
+      curr->start = pos;
+      curr->deflate_data = p;
+
+      z_stream strm;
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = st.st_size - pos;
+      strm.next_in = p;
+
+      // -15 means we are decoding a 'raw' deflate stream; zlib will
+      // not expect zlib headers.
+      int ret = inflateInit2(&strm, -15);
+
+      do {
+        strm.avail_out = allocated - curr->len;
+        strm.next_out = curr->data + curr->len;
+        ret = inflate(&strm, Z_NO_FLUSH);
+        curr->len = allocated - strm.avail_out;
+        if (strm.avail_out == 0) {
+          allocated *= 2;
+          curr->data = realloc(curr->data, allocated);
+        }
+      } while (ret != Z_STREAM_END);
+
+      curr->deflate_len = st.st_size - strm.avail_in - pos;
+      inflateEnd(&strm);
+      pos += curr->deflate_len;
+      p += curr->deflate_len;
+      ++curr;
+
+      // create a normal chunk for the footer
+
+      curr->type = CHUNK_NORMAL;
+      curr->start = pos;
+      curr->len = GZIP_FOOTER_LEN;
+      curr->data = img+pos;
+      curr->I = NULL;
+
+      pos += curr->len;
+      p += curr->len;
+      ++curr;
+
+      // The footer (that we just skipped over) contains the size of
+      // the uncompressed data.  Double-check to make sure that it
+      // matches the size of the data we got when we actually did
+      // the decompression.
+      size_t footer_size = Read4(p-4);
+      if (footer_size != curr[-2].len) {
+        printf("Error: footer size %d != decompressed size %d\n",
+                footer_size, curr[-2].len);
+        free(img);
+        return NULL;
+      }
+    } else {
+      // Reallocate the list for every chunk; we expect the number of
+      // chunks to be small (5 for typical boot and recovery images).
+      ++*num_chunks;
+      *chunks = realloc(*chunks, *num_chunks * sizeof(ImageChunk));
+      ImageChunk* curr = *chunks + (*num_chunks-1);
+      curr->start = pos;
+      curr->I = NULL;
+
+      // 'pos' is not the offset of the start of a gzip chunk, so scan
+      // forward until we find a gzip header.
+      curr->type = CHUNK_NORMAL;
+      curr->data = p;
+
+      for (curr->len = 0; curr->len < (st.st_size - pos); ++curr->len) {
+        if (p[curr->len] == 0x1f &&
+            p[curr->len+1] == 0x8b &&
+            p[curr->len+2] == 0x08 &&
+            p[curr->len+3] == 0x00) {
+          break;
+        }
+      }
+      pos += curr->len;
+    }
+  }
+
+  return img;
+}
+
+#define BUFFER_SIZE 32768
+
+/*
+ * Takes the uncompressed data stored in the chunk, compresses it
+ * using the zlib parameters stored in the chunk, and checks that it
+ * matches exactly the compressed data we started with (also stored in
+ * the chunk).  Return 0 on success.
+ */
+int TryReconstruction(ImageChunk* chunk, unsigned char* out) {
+  size_t p = 0;
+
+#if 0
+  printf("trying %d %d %d %d %d\n",
+          chunk->level, chunk->method, chunk->windowBits,
+          chunk->memLevel, chunk->strategy);
+#endif
+
+  z_stream strm;
+  strm.zalloc = Z_NULL;
+  strm.zfree = Z_NULL;
+  strm.opaque = Z_NULL;
+  strm.avail_in = chunk->len;
+  strm.next_in = chunk->data;
+  int ret;
+  ret = deflateInit2(&strm, chunk->level, chunk->method, chunk->windowBits,
+                     chunk->memLevel, chunk->strategy);
+  do {
+    strm.avail_out = BUFFER_SIZE;
+    strm.next_out = out;
+    ret = deflate(&strm, Z_FINISH);
+    size_t have = BUFFER_SIZE - strm.avail_out;
+
+    if (memcmp(out, chunk->deflate_data+p, have) != 0) {
+      // mismatch; data isn't the same.
+      deflateEnd(&strm);
+      return -1;
+    }
+    p += have;
+  } while (ret != Z_STREAM_END);
+  deflateEnd(&strm);
+  if (p != chunk->deflate_len) {
+    // mismatch; ran out of data before we should have.
+    return -1;
+  }
+  return 0;
+}
+
+/*
+ * Verify that we can reproduce exactly the same compressed data that
+ * we started with.  Sets the level, method, windowBits, memLevel, and
+ * strategy fields in the chunk to the encoding parameters needed to
+ * produce the right output.  Returns 0 on success.
+ */
+int ReconstructDeflateChunk(ImageChunk* chunk) {
+  if (chunk->type != CHUNK_DEFLATE) {
+    printf("attempt to reconstruct non-deflate chunk\n");
+    return -1;
+  }
+
+  size_t p = 0;
+  unsigned char* out = malloc(BUFFER_SIZE);
+
+  // We only check two combinations of encoder parameters:  level 6
+  // (the default) and level 9 (the maximum).
+  for (chunk->level = 6; chunk->level <= 9; chunk->level += 3) {
+    chunk->windowBits = -15;  // 32kb window; negative to indicate a raw stream.
+    chunk->memLevel = 8;      // the default value.
+    chunk->method = Z_DEFLATED;
+    chunk->strategy = Z_DEFAULT_STRATEGY;
+
+    if (TryReconstruction(chunk, out) == 0) {
+      free(out);
+      return 0;
+    }
+  }
+
+  free(out);
+  return -1;
+}
+
+/*
+ * Given source and target chunks, compute a bsdiff patch between them
+ * by running bsdiff in a subprocess.  Return the patch data, placing
+ * its length in *size.  Return NULL on failure.  We expect the bsdiff
+ * program to be in the path.
+ */
+unsigned char* MakePatch(ImageChunk* src, ImageChunk* tgt, size_t* size) {
+  if (tgt->type == CHUNK_NORMAL) {
+    if (tgt->len <= 160) {
+      tgt->type = CHUNK_RAW;
+      *size = tgt->len;
+      return tgt->data;
+    }
+  }
+
+  char ptemp[] = "/tmp/imgdiff-patch-XXXXXX";
+  mkstemp(ptemp);
+
+  int r = bsdiff(src->data, src->len, &(src->I), tgt->data, tgt->len, ptemp);
+  if (r != 0) {
+    printf("bsdiff() failed: %d\n", r);
+    return NULL;
+  }
+
+  struct stat st;
+  if (stat(ptemp, &st) != 0) {
+    printf("failed to stat patch file %s: %s\n",
+            ptemp, strerror(errno));
+    return NULL;
+  }
+
+  unsigned char* data = malloc(st.st_size);
+
+  if (tgt->type == CHUNK_NORMAL && tgt->len <= st.st_size) {
+    unlink(ptemp);
+
+    tgt->type = CHUNK_RAW;
+    *size = tgt->len;
+    return tgt->data;
+  }
+
+  *size = st.st_size;
+
+  FILE* f = fopen(ptemp, "rb");
+  if (f == NULL) {
+    printf("failed to open patch %s: %s\n", ptemp, strerror(errno));
+    return NULL;
+  }
+  if (fread(data, 1, st.st_size, f) != st.st_size) {
+    printf("failed to read patch %s: %s\n", ptemp, strerror(errno));
+    return NULL;
+  }
+  fclose(f);
+
+  unlink(ptemp);
+
+  tgt->source_start = src->start;
+  switch (tgt->type) {
+    case CHUNK_NORMAL:
+      tgt->source_len = src->len;
+      break;
+    case CHUNK_DEFLATE:
+      tgt->source_len = src->deflate_len;
+      tgt->source_uncompressed_len = src->len;
+      break;
+  }
+
+  return data;
+}
+
+/*
+ * Cause a gzip chunk to be treated as a normal chunk (ie, as a blob
+ * of uninterpreted data).  The resulting patch will likely be about
+ * as big as the target file, but it lets us handle the case of images
+ * where some gzip chunks are reconstructible but others aren't (by
+ * treating the ones that aren't as normal chunks).
+ */
+void ChangeDeflateChunkToNormal(ImageChunk* ch) {
+  if (ch->type != CHUNK_DEFLATE) return;
+  ch->type = CHUNK_NORMAL;
+  free(ch->data);
+  ch->data = ch->deflate_data;
+  ch->len = ch->deflate_len;
+}
+
+/*
+ * Return true if the data in the chunk is identical (including the
+ * compressed representation, for gzip chunks).
+ */
+int AreChunksEqual(ImageChunk* a, ImageChunk* b) {
+    if (a->type != b->type) return 0;
+
+    switch (a->type) {
+        case CHUNK_NORMAL:
+            return a->len == b->len && memcmp(a->data, b->data, a->len) == 0;
+
+        case CHUNK_DEFLATE:
+            return a->deflate_len == b->deflate_len &&
+                memcmp(a->deflate_data, b->deflate_data, a->deflate_len) == 0;
+
+        default:
+            printf("unknown chunk type %d\n", a->type);
+            return 0;
+    }
+}
+
+/*
+ * Look for runs of adjacent normal chunks and compress them down into
+ * a single chunk.  (Such runs can be produced when deflate chunks are
+ * changed to normal chunks.)
+ */
+void MergeAdjacentNormalChunks(ImageChunk* chunks, int* num_chunks) {
+  int out = 0;
+  int in_start = 0, in_end;
+  while (in_start < *num_chunks) {
+    if (chunks[in_start].type != CHUNK_NORMAL) {
+      in_end = in_start+1;
+    } else {
+      // in_start is a normal chunk.  Look for a run of normal chunks
+      // that constitute a solid block of data (ie, each chunk begins
+      // where the previous one ended).
+      for (in_end = in_start+1;
+           in_end < *num_chunks && chunks[in_end].type == CHUNK_NORMAL &&
+             (chunks[in_end].start ==
+              chunks[in_end-1].start + chunks[in_end-1].len &&
+              chunks[in_end].data ==
+              chunks[in_end-1].data + chunks[in_end-1].len);
+           ++in_end);
+    }
+
+    if (in_end == in_start+1) {
+#if 0
+      printf("chunk %d is now %d\n", in_start, out);
+#endif
+      if (out != in_start) {
+        memcpy(chunks+out, chunks+in_start, sizeof(ImageChunk));
+      }
+    } else {
+#if 0
+      printf("collapse normal chunks %d-%d into %d\n", in_start, in_end-1, out);
+#endif
+
+      // Merge chunks [in_start, in_end-1] into one chunk.  Since the
+      // data member of each chunk is just a pointer into an in-memory
+      // copy of the file, this can be done without recopying (the
+      // output chunk has the first chunk's start location and data
+      // pointer, and length equal to the sum of the input chunk
+      // lengths).
+      chunks[out].type = CHUNK_NORMAL;
+      chunks[out].start = chunks[in_start].start;
+      chunks[out].data = chunks[in_start].data;
+      chunks[out].len = chunks[in_end-1].len +
+        (chunks[in_end-1].start - chunks[in_start].start);
+    }
+
+    ++out;
+    in_start = in_end;
+  }
+  *num_chunks = out;
+}
+
+ImageChunk* FindChunkByName(const char* name,
+                            ImageChunk* chunks, int num_chunks) {
+  int i;
+  for (i = 0; i < num_chunks; ++i) {
+    if (chunks[i].type == CHUNK_DEFLATE && chunks[i].filename &&
+        strcmp(name, chunks[i].filename) == 0) {
+      return chunks+i;
+    }
+  }
+  return NULL;
+}
+
+void DumpChunks(ImageChunk* chunks, int num_chunks) {
+    int i;
+    for (i = 0; i < num_chunks; ++i) {
+        printf("chunk %d: type %d start %d len %d\n",
+               i, chunks[i].type, chunks[i].start, chunks[i].len);
+    }
+}
+
+int main(int argc, char** argv) {
+  if (argc != 4 && argc != 5) {
+    usage:
+    printf("usage: %s [-z] <src-img> <tgt-img> <patch-file>\n",
+            argv[0]);
+    return 2;
+  }
+
+  int zip_mode = 0;
+
+  if (strcmp(argv[1], "-z") == 0) {
+    zip_mode = 1;
+    --argc;
+    ++argv;
+  }
+
+
+  int num_src_chunks;
+  ImageChunk* src_chunks;
+  int num_tgt_chunks;
+  ImageChunk* tgt_chunks;
+  int i;
+
+  if (zip_mode) {
+    if (ReadZip(argv[1], &num_src_chunks, &src_chunks, 1) == NULL) {
+      printf("failed to break apart source zip file\n");
+      return 1;
+    }
+    if (ReadZip(argv[2], &num_tgt_chunks, &tgt_chunks, 0) == NULL) {
+      printf("failed to break apart target zip file\n");
+      return 1;
+    }
+  } else {
+    if (ReadImage(argv[1], &num_src_chunks, &src_chunks) == NULL) {
+      printf("failed to break apart source image\n");
+      return 1;
+    }
+    if (ReadImage(argv[2], &num_tgt_chunks, &tgt_chunks) == NULL) {
+      printf("failed to break apart target image\n");
+      return 1;
+    }
+
+    // Verify that the source and target images have the same chunk
+    // structure (ie, the same sequence of deflate and normal chunks).
+
+    if (!zip_mode) {
+        // Merge the gzip header and footer in with any adjacent
+        // normal chunks.
+        MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
+        MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
+    }
+
+    if (num_src_chunks != num_tgt_chunks) {
+      printf("source and target don't have same number of chunks!\n");
+      printf("source chunks:\n");
+      DumpChunks(src_chunks, num_src_chunks);
+      printf("target chunks:\n");
+      DumpChunks(tgt_chunks, num_tgt_chunks);
+      return 1;
+    }
+    for (i = 0; i < num_src_chunks; ++i) {
+      if (src_chunks[i].type != tgt_chunks[i].type) {
+        printf("source and target don't have same chunk "
+                "structure! (chunk %d)\n", i);
+        printf("source chunks:\n");
+        DumpChunks(src_chunks, num_src_chunks);
+        printf("target chunks:\n");
+        DumpChunks(tgt_chunks, num_tgt_chunks);
+        return 1;
+      }
+    }
+  }
+
+  for (i = 0; i < num_tgt_chunks; ++i) {
+    if (tgt_chunks[i].type == CHUNK_DEFLATE) {
+      // Confirm that given the uncompressed chunk data in the target, we
+      // can recompress it and get exactly the same bits as are in the
+      // input target image.  If this fails, treat the chunk as a normal
+      // non-deflated chunk.
+      if (ReconstructDeflateChunk(tgt_chunks+i) < 0) {
+        printf("failed to reconstruct target deflate chunk %d [%s]; "
+               "treating as normal\n", i, tgt_chunks[i].filename);
+        ChangeDeflateChunkToNormal(tgt_chunks+i);
+        if (zip_mode) {
+          ImageChunk* src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
+          if (src) {
+            ChangeDeflateChunkToNormal(src);
+          }
+        } else {
+          ChangeDeflateChunkToNormal(src_chunks+i);
+        }
+        continue;
+      }
+
+      // If two deflate chunks are identical (eg, the kernel has not
+      // changed between two builds), treat them as normal chunks.
+      // This makes applypatch much faster -- it can apply a trivial
+      // patch to the compressed data, rather than uncompressing and
+      // recompressing to apply the trivial patch to the uncompressed
+      // data.
+      ImageChunk* src;
+      if (zip_mode) {
+        src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
+      } else {
+        src = src_chunks+i;
+      }
+
+      if (src == NULL || AreChunksEqual(tgt_chunks+i, src)) {
+        ChangeDeflateChunkToNormal(tgt_chunks+i);
+        if (src) {
+          ChangeDeflateChunkToNormal(src);
+        }
+      }
+    }
+  }
+
+  // Merging neighboring normal chunks.
+  if (zip_mode) {
+    // For zips, we only need to do this to the target:  deflated
+    // chunks are matched via filename, and normal chunks are patched
+    // using the entire source file as the source.
+    MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
+  } else {
+    // For images, we need to maintain the parallel structure of the
+    // chunk lists, so do the merging in both the source and target
+    // lists.
+    MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
+    MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
+    if (num_src_chunks != num_tgt_chunks) {
+      // This shouldn't happen.
+      printf("merging normal chunks went awry\n");
+      return 1;
+    }
+  }
+
+  // Compute bsdiff patches for each chunk's data (the uncompressed
+  // data, in the case of deflate chunks).
+
+  printf("Construct patches for %d chunks...\n", num_tgt_chunks);
+  unsigned char** patch_data = malloc(num_tgt_chunks * sizeof(unsigned char*));
+  size_t* patch_size = malloc(num_tgt_chunks * sizeof(size_t));
+  for (i = 0; i < num_tgt_chunks; ++i) {
+    if (zip_mode) {
+      ImageChunk* src;
+      if (tgt_chunks[i].type == CHUNK_DEFLATE &&
+          (src = FindChunkByName(tgt_chunks[i].filename, src_chunks,
+                                 num_src_chunks))) {
+        patch_data[i] = MakePatch(src, tgt_chunks+i, patch_size+i);
+      } else {
+        patch_data[i] = MakePatch(src_chunks, tgt_chunks+i, patch_size+i);
+      }
+    } else {
+      patch_data[i] = MakePatch(src_chunks+i, tgt_chunks+i, patch_size+i);
+    }
+    printf("patch %3d is %d bytes (of %d)\n",
+           i, patch_size[i], tgt_chunks[i].source_len);
+  }
+
+  // Figure out how big the imgdiff file header is going to be, so
+  // that we can correctly compute the offset of each bsdiff patch
+  // within the file.
+
+  size_t total_header_size = 12;
+  for (i = 0; i < num_tgt_chunks; ++i) {
+    total_header_size += 4;
+    switch (tgt_chunks[i].type) {
+      case CHUNK_NORMAL:
+        total_header_size += 8*3;
+        break;
+      case CHUNK_DEFLATE:
+        total_header_size += 8*5 + 4*5;
+        break;
+      case CHUNK_RAW:
+        total_header_size += 4 + patch_size[i];
+        break;
+    }
+  }
+
+  size_t offset = total_header_size;
+
+  FILE* f = fopen(argv[3], "wb");
+
+  // Write out the headers.
+
+  fwrite("IMGDIFF2", 1, 8, f);
+  Write4(num_tgt_chunks, f);
+  for (i = 0; i < num_tgt_chunks; ++i) {
+    Write4(tgt_chunks[i].type, f);
+
+    switch (tgt_chunks[i].type) {
+      case CHUNK_NORMAL:
+        printf("chunk %3d: normal   (%10d, %10d)  %10d\n", i,
+               tgt_chunks[i].start, tgt_chunks[i].len, patch_size[i]);
+        Write8(tgt_chunks[i].source_start, f);
+        Write8(tgt_chunks[i].source_len, f);
+        Write8(offset, f);
+        offset += patch_size[i];
+        break;
+
+      case CHUNK_DEFLATE:
+        printf("chunk %3d: deflate  (%10d, %10d)  %10d  %s\n", i,
+               tgt_chunks[i].start, tgt_chunks[i].deflate_len, patch_size[i],
+               tgt_chunks[i].filename);
+        Write8(tgt_chunks[i].source_start, f);
+        Write8(tgt_chunks[i].source_len, f);
+        Write8(offset, f);
+        Write8(tgt_chunks[i].source_uncompressed_len, f);
+        Write8(tgt_chunks[i].len, f);
+        Write4(tgt_chunks[i].level, f);
+        Write4(tgt_chunks[i].method, f);
+        Write4(tgt_chunks[i].windowBits, f);
+        Write4(tgt_chunks[i].memLevel, f);
+        Write4(tgt_chunks[i].strategy, f);
+        offset += patch_size[i];
+        break;
+
+      case CHUNK_RAW:
+        printf("chunk %3d: raw      (%10d, %10d)\n", i,
+               tgt_chunks[i].start, tgt_chunks[i].len);
+        Write4(patch_size[i], f);
+        fwrite(patch_data[i], 1, patch_size[i], f);
+        break;
+    }
+  }
+
+  // Append each chunk's bsdiff patch, in order.
+
+  for (i = 0; i < num_tgt_chunks; ++i) {
+    if (tgt_chunks[i].type != CHUNK_RAW) {
+      fwrite(patch_data[i], 1, patch_size[i], f);
+    }
+  }
+
+  fclose(f);
+
+  return 0;
+}
diff --git a/applypatch/imgdiff.h b/applypatch/imgdiff.h
new file mode 100644
index 0000000..f2069b4
--- /dev/null
+++ b/applypatch/imgdiff.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Image patch chunk types
+#define CHUNK_NORMAL   0
+#define CHUNK_GZIP     1   // version 1 only
+#define CHUNK_DEFLATE  2   // version 2 only
+#define CHUNK_RAW      3   // version 2 only
+
+// The gzip header size is actually variable, but we currently don't
+// support gzipped data with any of the optional fields, so for now it
+// will always be ten bytes.  See RFC 1952 for the definition of the
+// gzip format.
+#define GZIP_HEADER_LEN   10
+
+// The gzip footer size really is fixed.
+#define GZIP_FOOTER_LEN   8
diff --git a/applypatch/imgdiff_test.sh b/applypatch/imgdiff_test.sh
new file mode 100755
index 0000000..dcdb922
--- /dev/null
+++ b/applypatch/imgdiff_test.sh
@@ -0,0 +1,118 @@
+#!/bin/bash
+#
+# A script for testing imgdiff/applypatch.  It takes two full OTA
+# packages as arguments.  It generates (on the host) patches for all
+# the zip/jar/apk files they have in common, as well as boot and
+# recovery images.  It then applies the patches on the device (or
+# emulator) and checks that the resulting file is correct.
+
+EMULATOR_PORT=5580
+
+# set to 0 to use a device instead
+USE_EMULATOR=0
+
+# where on the device to do all the patching.
+WORK_DIR=/data/local/tmp
+
+START_OTA_PACKAGE=$1
+END_OTA_PACKAGE=$2
+
+# ------------------------
+
+tmpdir=$(mktemp -d)
+
+if [ "$USE_EMULATOR" == 1 ]; then
+  emulator -wipe-data -noaudio -no-window -port $EMULATOR_PORT &
+  pid_emulator=$!
+  ADB="adb -s emulator-$EMULATOR_PORT "
+else
+  ADB="adb -d "
+fi
+
+echo "waiting to connect to device"
+$ADB wait-for-device
+
+# run a command on the device; exit with the exit status of the device
+# command.
+run_command() {
+  $ADB shell "$@" \; echo \$? | awk '{if (b) {print a}; a=$0; b=1} END {exit a}'
+}
+
+testname() {
+  echo
+  echo "$1"...
+  testname="$1"
+}
+
+fail() {
+  echo
+  echo FAIL: $testname
+  echo
+  [ "$open_pid" == "" ] || kill $open_pid
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
+  exit 1
+}
+
+sha1() {
+  sha1sum $1 | awk '{print $1}'
+}
+
+size() {
+  stat -c %s $1 | tr -d '\n'
+}
+
+cleanup() {
+  # not necessary if we're about to kill the emulator, but nice for
+  # running on real devices or already-running emulators.
+  testname "removing test files"
+  run_command rm $WORK_DIR/applypatch
+  run_command rm $WORK_DIR/source
+  run_command rm $WORK_DIR/target
+  run_command rm $WORK_DIR/patch
+
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
+
+  rm -rf $tmpdir
+}
+
+$ADB push $ANDROID_PRODUCT_OUT/system/bin/applypatch $WORK_DIR/applypatch
+
+patch_and_apply() {
+  local fn=$1
+  shift
+
+  unzip -p $START_OTA_PACKAGE $fn > $tmpdir/source
+  unzip -p $END_OTA_PACKAGE $fn > $tmpdir/target
+  imgdiff "$@" $tmpdir/source $tmpdir/target $tmpdir/patch
+  bsdiff $tmpdir/source $tmpdir/target $tmpdir/patch.bs
+  echo "patch for $fn is $(size $tmpdir/patch) [of $(size $tmpdir/target)] ($(size $tmpdir/patch.bs) with bsdiff)"
+  echo "$fn $(size $tmpdir/patch) of $(size $tmpdir/target) bsdiff $(size $tmpdir/patch.bs)" >> /tmp/stats.txt
+  $ADB push $tmpdir/source $WORK_DIR/source || fail "source push failed"
+  run_command rm /data/local/tmp/target
+  $ADB push $tmpdir/patch $WORK_DIR/patch || fail "patch push failed"
+  run_command /data/local/tmp/applypatch /data/local/tmp/source \
+    /data/local/tmp/target $(sha1 $tmpdir/target) $(size $tmpdir/target) \
+    $(sha1 $tmpdir/source):/data/local/tmp/patch \
+    || fail "applypatch of $fn failed"
+  $ADB pull /data/local/tmp/target $tmpdir/result
+  diff -q $tmpdir/target $tmpdir/result || fail "patch output not correct!"
+}
+
+# --------------- basic execution ----------------------
+
+for i in $((zipinfo -1 $START_OTA_PACKAGE; zipinfo -1 $END_OTA_PACKAGE) | \
+           sort | uniq -d | egrep -e '[.](apk|jar|zip)$'); do
+  patch_and_apply $i -z
+done
+patch_and_apply boot.img
+patch_and_apply system/recovery.img
+
+
+# --------------- cleanup ----------------------
+
+cleanup
+
+echo
+echo PASS
+echo
+
diff --git a/applypatch/imgpatch.c b/applypatch/imgpatch.c
new file mode 100644
index 0000000..5322817
--- /dev/null
+++ b/applypatch/imgpatch.c
@@ -0,0 +1,364 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// See imgdiff.c in this directory for a description of the patch file
+// format.
+
+#include <stdio.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "zlib.h"
+#include "mincrypt/sha.h"
+#include "applypatch.h"
+#include "imgdiff.h"
+#include "utils.h"
+
+/*
+ * Apply the patch given in 'patch_filename' to the source data given
+ * by (old_data, old_size).  Write the patched output to the 'output'
+ * file, and update the SHA context with the output data as well.
+ * Return 0 on success.
+ */
+int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
+                    const char* patch_filename,
+                    SinkFn sink, void* token, SHA_CTX* ctx) {
+  FILE* f;
+  if ((f = fopen(patch_filename, "rb")) == NULL) {
+    printf("failed to open patch file\n");
+    return -1;
+  }
+
+  unsigned char header[12];
+  if (fread(header, 1, 12, f) != 12) {
+    printf("failed to read patch file header\n");
+    return -1;
+  }
+
+  // IMGDIFF1 uses CHUNK_NORMAL and CHUNK_GZIP.
+  // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
+  if (memcmp(header, "IMGDIFF", 7) != 0 ||
+      (header[7] != '1' && header[7] != '2')) {
+    printf("corrupt patch file header (magic number)\n");
+    return -1;
+  }
+
+  int num_chunks = Read4(header+8);
+
+  int i;
+  for (i = 0; i < num_chunks; ++i) {
+    // each chunk's header record starts with 4 bytes.
+    unsigned char chunk[4];
+    if (fread(chunk, 1, 4, f) != 4) {
+      printf("failed to read chunk %d record\n", i);
+      return -1;
+    }
+
+    int type = Read4(chunk);
+
+    if (type == CHUNK_NORMAL) {
+      unsigned char normal_header[24];
+      if (fread(normal_header, 1, 24, f) != 24) {
+        printf("failed to read chunk %d normal header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = Read8(normal_header);
+      size_t src_len = Read8(normal_header+8);
+      size_t patch_offset = Read8(normal_header+16);
+
+      printf("CHUNK %d:  normal   patch offset %d\n", i, patch_offset);
+
+      ApplyBSDiffPatch(old_data + src_start, src_len,
+                       patch_filename, patch_offset,
+                       sink, token, ctx);
+    } else if (type == CHUNK_GZIP) {
+      // This branch is basically a duplicate of the CHUNK_DEFLATE
+      // branch, with a bit of extra processing for the gzip header
+      // and footer.  I've avoided factoring the common code out since
+      // this branch will just be deleted when we drop support for
+      // IMGDIFF1.
+
+      // gzip chunks have an additional 64 + gzip_header_len + 8 bytes
+      // in their chunk header.
+      unsigned char* gzip = malloc(64);
+      if (fread(gzip, 1, 64, f) != 64) {
+        printf("failed to read chunk %d initial gzip header data\n",
+                i);
+        return -1;
+      }
+      size_t gzip_header_len = Read4(gzip+60);
+      gzip = realloc(gzip, 64 + gzip_header_len + 8);
+      if (fread(gzip+64, 1, gzip_header_len+8, f) != gzip_header_len+8) {
+        printf("failed to read chunk %d remaining gzip header data\n",
+                i);
+        return -1;
+      }
+
+      size_t src_start = Read8(gzip);
+      size_t src_len = Read8(gzip+8);
+      size_t patch_offset = Read8(gzip+16);
+
+      size_t expanded_len = Read8(gzip+24);
+      size_t target_len = Read8(gzip+32);
+      int gz_level = Read4(gzip+40);
+      int gz_method = Read4(gzip+44);
+      int gz_windowBits = Read4(gzip+48);
+      int gz_memLevel = Read4(gzip+52);
+      int gz_strategy = Read4(gzip+56);
+
+      printf("CHUNK %d:  gzip     patch offset %d\n", i, patch_offset);
+
+      // Decompress the source data; the chunk header tells us exactly
+      // how big we expect it to be when decompressed.
+
+      unsigned char* expanded_source = malloc(expanded_len);
+      if (expanded_source == NULL) {
+        printf("failed to allocate %d bytes for expanded_source\n",
+                expanded_len);
+        return -1;
+      }
+
+      z_stream strm;
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = src_len - (gzip_header_len + 8);
+      strm.next_in = (unsigned char*)(old_data + src_start + gzip_header_len);
+      strm.avail_out = expanded_len;
+      strm.next_out = expanded_source;
+
+      int ret;
+      ret = inflateInit2(&strm, -15);
+      if (ret != Z_OK) {
+        printf("failed to init source inflation: %d\n", ret);
+        return -1;
+      }
+
+      // Because we've provided enough room to accommodate the output
+      // data, we expect one call to inflate() to suffice.
+      ret = inflate(&strm, Z_SYNC_FLUSH);
+      if (ret != Z_STREAM_END) {
+        printf("source inflation returned %d\n", ret);
+        return -1;
+      }
+      // We should have filled the output buffer exactly.
+      if (strm.avail_out != 0) {
+        printf("source inflation short by %d bytes\n", strm.avail_out);
+        return -1;
+      }
+      inflateEnd(&strm);
+
+      // Next, apply the bsdiff patch (in memory) to the uncompressed
+      // data.
+      unsigned char* uncompressed_target_data;
+      ssize_t uncompressed_target_size;
+      if (ApplyBSDiffPatchMem(expanded_source, expanded_len,
+                              patch_filename, patch_offset,
+                              &uncompressed_target_data,
+                              &uncompressed_target_size) != 0) {
+        return -1;
+      }
+
+      // Now compress the target data and append it to the output.
+
+      // start with the gzip header.
+      sink(gzip+64, gzip_header_len, token);
+      SHA_update(ctx, gzip+64, gzip_header_len);
+
+      // we're done with the expanded_source data buffer, so we'll
+      // reuse that memory to receive the output of deflate.
+      unsigned char* temp_data = expanded_source;
+      ssize_t temp_size = expanded_len;
+      if (temp_size < 32768) {
+        // ... unless the buffer is too small, in which case we'll
+        // allocate a fresh one.
+        free(temp_data);
+        temp_data = malloc(32768);
+        temp_size = 32768;
+      }
+
+      // now the deflate stream
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = uncompressed_target_size;
+      strm.next_in = uncompressed_target_data;
+      ret = deflateInit2(&strm, gz_level, gz_method, gz_windowBits,
+                         gz_memLevel, gz_strategy);
+      do {
+        strm.avail_out = temp_size;
+        strm.next_out = temp_data;
+        ret = deflate(&strm, Z_FINISH);
+        size_t have = temp_size - strm.avail_out;
+
+        if (sink(temp_data, have, token) != have) {
+          printf("failed to write %d compressed bytes to output\n",
+                  have);
+          return -1;
+        }
+        SHA_update(ctx, temp_data, have);
+      } while (ret != Z_STREAM_END);
+      deflateEnd(&strm);
+
+      // lastly, the gzip footer.
+      sink(gzip+64+gzip_header_len, 8, token);
+      SHA_update(ctx, gzip+64+gzip_header_len, 8);
+
+      free(temp_data);
+      free(uncompressed_target_data);
+      free(gzip);
+    } else if (type == CHUNK_RAW) {
+      unsigned char raw_header[4];
+      if (fread(raw_header, 1, 4, f) != 4) {
+        printf("failed to read chunk %d raw header data\n", i);
+        return -1;
+      }
+
+      size_t data_len = Read4(raw_header);
+
+      printf("CHUNK %d:  raw      data %d\n", i, data_len);
+
+      unsigned char* temp = malloc(data_len);
+      if (fread(temp, 1, data_len, f) != data_len) {
+          printf("failed to read chunk %d raw data\n", i);
+          return -1;
+      }
+      SHA_update(ctx, temp, data_len);
+      if (sink(temp, data_len, token) != data_len) {
+          printf("failed to write chunk %d raw data\n", i);
+          return -1;
+      }
+    } else if (type == CHUNK_DEFLATE) {
+      // deflate chunks have an additional 60 bytes in their chunk header.
+      unsigned char deflate_header[60];
+      if (fread(deflate_header, 1, 60, f) != 60) {
+        printf("failed to read chunk %d deflate header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = Read8(deflate_header);
+      size_t src_len = Read8(deflate_header+8);
+      size_t patch_offset = Read8(deflate_header+16);
+      size_t expanded_len = Read8(deflate_header+24);
+      size_t target_len = Read8(deflate_header+32);
+      int level = Read4(deflate_header+40);
+      int method = Read4(deflate_header+44);
+      int windowBits = Read4(deflate_header+48);
+      int memLevel = Read4(deflate_header+52);
+      int strategy = Read4(deflate_header+56);
+
+      printf("CHUNK %d:  deflate  patch offset %d\n", i, patch_offset);
+
+      // Decompress the source data; the chunk header tells us exactly
+      // how big we expect it to be when decompressed.
+
+      unsigned char* expanded_source = malloc(expanded_len);
+      if (expanded_source == NULL) {
+        printf("failed to allocate %d bytes for expanded_source\n",
+                expanded_len);
+        return -1;
+      }
+
+      z_stream strm;
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = src_len;
+      strm.next_in = (unsigned char*)(old_data + src_start);
+      strm.avail_out = expanded_len;
+      strm.next_out = expanded_source;
+
+      int ret;
+      ret = inflateInit2(&strm, -15);
+      if (ret != Z_OK) {
+        printf("failed to init source inflation: %d\n", ret);
+        return -1;
+      }
+
+      // Because we've provided enough room to accommodate the output
+      // data, we expect one call to inflate() to suffice.
+      ret = inflate(&strm, Z_SYNC_FLUSH);
+      if (ret != Z_STREAM_END) {
+        printf("source inflation returned %d\n", ret);
+        return -1;
+      }
+      // We should have filled the output buffer exactly.
+      if (strm.avail_out != 0) {
+        printf("source inflation short by %d bytes\n", strm.avail_out);
+        return -1;
+      }
+      inflateEnd(&strm);
+
+      // Next, apply the bsdiff patch (in memory) to the uncompressed
+      // data.
+      unsigned char* uncompressed_target_data;
+      ssize_t uncompressed_target_size;
+      if (ApplyBSDiffPatchMem(expanded_source, expanded_len,
+                              patch_filename, patch_offset,
+                              &uncompressed_target_data,
+                              &uncompressed_target_size) != 0) {
+        return -1;
+      }
+
+      // Now compress the target data and append it to the output.
+
+      // we're done with the expanded_source data buffer, so we'll
+      // reuse that memory to receive the output of deflate.
+      unsigned char* temp_data = expanded_source;
+      ssize_t temp_size = expanded_len;
+      if (temp_size < 32768) {
+        // ... unless the buffer is too small, in which case we'll
+        // allocate a fresh one.
+        free(temp_data);
+        temp_data = malloc(32768);
+        temp_size = 32768;
+      }
+
+      // now the deflate stream
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = uncompressed_target_size;
+      strm.next_in = uncompressed_target_data;
+      ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
+      do {
+        strm.avail_out = temp_size;
+        strm.next_out = temp_data;
+        ret = deflate(&strm, Z_FINISH);
+        size_t have = temp_size - strm.avail_out;
+
+        if (sink(temp_data, have, token) != have) {
+          printf("failed to write %d compressed bytes to output\n",
+                  have);
+          return -1;
+        }
+        SHA_update(ctx, temp_data, have);
+      } while (ret != Z_STREAM_END);
+      deflateEnd(&strm);
+
+      free(temp_data);
+      free(uncompressed_target_data);
+    } else {
+      printf("patch chunk %d is unknown type %d\n", i, type);
+      return -1;
+    }
+  }
+
+  return 0;
+}
diff --git a/applypatch/main.c b/applypatch/main.c
new file mode 100644
index 0000000..e08f5c1
--- /dev/null
+++ b/applypatch/main.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+
+extern int applypatch(int argc, char** argv);
+
+// This program applies binary patches to files in a way that is safe
+// (the original file is not touched until we have the desired
+// replacement for it) and idempotent (it's okay to run this program
+// multiple times).
+//
+// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
+//   successfully.
+//
+// - otherwise, if the sha1 hash of <src-file> is <src-sha1>, applies the
+//   bsdiff <patch> to <src-file> to produce a new file (the type of patch
+//   is automatically detected from the file header).  If that new
+//   file has sha1 hash <tgt-sha1>, moves it to replace <tgt-file>, and
+//   exits successfully.  Note that if <src-file> and <tgt-file> are
+//   not the same, <src-file> is NOT deleted on success.  <tgt-file>
+//   may be the string "-" to mean "the same as src-file".
+//
+// - otherwise, or if any error is encountered, exits with non-zero
+//   status.
+//
+// <src-file> (or <file> in check mode) may refer to an MTD partition
+// to read the source data.  See the comments for the
+// LoadMTDContents() function above for the format of such a filename.
+
+int main(int argc, char** argv) {
+  int result = applypatch(argc, argv);
+  if (result == 2) {
+    printf(
+            "usage: %s <src-file> <tgt-file> <tgt-sha1> <tgt-size> "
+            "[<src-sha1>:<patch> ...]\n"
+            "   or  %s -c <file> [<sha1> ...]\n"
+            "   or  %s -s <bytes>\n"
+            "   or  %s -l\n"
+            "\n"
+            "Filenames may be of the form\n"
+            "  MTD:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
+            "to specify reading from or writing to an MTD partition.\n\n",
+            argv[0], argv[0], argv[0], argv[0]);
+  }
+  return result;
+}
diff --git a/applypatch/testdata/new.file b/applypatch/testdata/new.file
new file mode 100644
index 0000000..cdeb8fd
--- /dev/null
+++ b/applypatch/testdata/new.file
diff --git a/applypatch/testdata/old.file b/applypatch/testdata/old.file
new file mode 100644
index 0000000..166c873
--- /dev/null
+++ b/applypatch/testdata/old.file
diff --git a/applypatch/testdata/patch.bsdiff b/applypatch/testdata/patch.bsdiff
new file mode 100644
index 0000000..b78d385
--- /dev/null
+++ b/applypatch/testdata/patch.bsdiff
diff --git a/applypatch/utils.c b/applypatch/utils.c
new file mode 100644
index 0000000..912229b
--- /dev/null
+++ b/applypatch/utils.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+
+#include "utils.h"
+
+/** Write a 4-byte value to f in little-endian order. */
+void Write4(int value, FILE* f) {
+  fputc(value & 0xff, f);
+  fputc((value >> 8) & 0xff, f);
+  fputc((value >> 16) & 0xff, f);
+  fputc((value >> 24) & 0xff, f);
+}
+
+/** Write an 8-byte value to f in little-endian order. */
+void Write8(long long value, FILE* f) {
+  fputc(value & 0xff, f);
+  fputc((value >> 8) & 0xff, f);
+  fputc((value >> 16) & 0xff, f);
+  fputc((value >> 24) & 0xff, f);
+  fputc((value >> 32) & 0xff, f);
+  fputc((value >> 40) & 0xff, f);
+  fputc((value >> 48) & 0xff, f);
+  fputc((value >> 56) & 0xff, f);
+}
+
+int Read2(unsigned char* p) {
+  return (int)(((unsigned int)p[1] << 8) |
+               (unsigned int)p[0]);
+}
+
+int Read4(unsigned char* p) {
+  return (int)(((unsigned int)p[3] << 24) |
+               ((unsigned int)p[2] << 16) |
+               ((unsigned int)p[1] << 8) |
+               (unsigned int)p[0]);
+}
+
+long long Read8(unsigned char* p) {
+  return (long long)(((unsigned long long)p[7] << 56) |
+                     ((unsigned long long)p[6] << 48) |
+                     ((unsigned long long)p[5] << 40) |
+                     ((unsigned long long)p[4] << 32) |
+                     ((unsigned long long)p[3] << 24) |
+                     ((unsigned long long)p[2] << 16) |
+                     ((unsigned long long)p[1] << 8) |
+                     (unsigned long long)p[0]);
+}
diff --git a/applypatch/utils.h b/applypatch/utils.h
new file mode 100644
index 0000000..d6d6f1d
--- /dev/null
+++ b/applypatch/utils.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _BUILD_TOOLS_APPLYPATCH_UTILS_H
+#define _BUILD_TOOLS_APPLYPATCH_UTILS_H
+
+#include <stdio.h>
+
+// Read and write little-endian values of various sizes.
+
+void Write4(int value, FILE* f);
+void Write8(long long value, FILE* f);
+int Read2(unsigned char* p);
+int Read4(unsigned char* p);
+long long Read8(unsigned char* p);
+
+#endif //  _BUILD_TOOLS_APPLYPATCH_UTILS_H
diff --git a/edify/expr.c b/edify/expr.c
index df3c1ab..7a5b2fb 100644
--- a/edify/expr.c
+++ b/edify/expr.c
@@ -33,12 +33,39 @@ int BooleanString(const char* s) {
 }
 
 char* Evaluate(State* state, Expr* expr) {
+    Value* v = expr->fn(expr->name, state, expr->argc, expr->argv);
+    if (v == NULL) return NULL;
+    if (v->type != VAL_STRING) {
+        ErrorAbort(state, "expecting string, got value type %d", v->type);
+        FreeValue(v);
+        return NULL;
+    }
+    char* result = v->data;
+    free(v);
+    return result;
+}
+
+Value* EvaluateValue(State* state, Expr* expr) {
     return expr->fn(expr->name, state, expr->argc, expr->argv);
 }
 
-char* ConcatFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* StringValue(char* str) {
+    Value* v = malloc(sizeof(Value));
+    v->type = VAL_STRING;
+    v->size = strlen(str);
+    v->data = str;
+    return v;
+}
+
+void FreeValue(Value* v) {
+    if (v == NULL) return;
+    free(v->data);
+    free(v);
+}
+
+Value* ConcatFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc == 0) {
-        return strdup("");
+        return StringValue(strdup(""));
     }
     char** strings = malloc(argc * sizeof(char*));
     int i;
@@ -68,10 +95,10 @@ char* ConcatFn(const char* name, State* state, int argc, Expr* argv[]) {
         free(strings[i]);
     }
     free(strings);
-    return result;
+    return StringValue(result);
 }
 
-char* IfElseFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* IfElseFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 2 && argc != 3) {
         free(state->errmsg);
         state->errmsg = strdup("ifelse expects 2 or 3 arguments");
@@ -84,18 +111,18 @@ char* IfElseFn(const char* name, State* state, int argc, Expr* argv[]) {
 
     if (BooleanString(cond) == true) {
         free(cond);
-        return Evaluate(state, argv[1]);
+        return EvaluateValue(state, argv[1]);
     } else {
         if (argc == 3) {
             free(cond);
-            return Evaluate(state, argv[2]);
+            return EvaluateValue(state, argv[2]);
         } else {
-            return cond;
+            return StringValue(cond);
         }
     }
 }
 
-char* AbortFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* AbortFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* msg = NULL;
     if (argc > 0) {
         msg = Evaluate(state, argv[0]);
@@ -109,7 +136,7 @@ char* AbortFn(const char* name, State* state, int argc, Expr* argv[]) {
     return NULL;
 }
 
-char* AssertFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* AssertFn(const char* name, State* state, int argc, Expr* argv[]) {
     int i;
     for (i = 0; i < argc; ++i) {
         char* v = Evaluate(state, argv[i]);
@@ -131,20 +158,20 @@ char* AssertFn(const char* name, State* state, int argc, Expr* argv[]) {
             return NULL;
         }
     }
-    return strdup("");
+    return StringValue(strdup(""));
 }
 
-char* SleepFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* SleepFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* val = Evaluate(state, argv[0]);
     if (val == NULL) {
         return NULL;
     }
     int v = strtol(val, NULL, 10);
     sleep(v);
-    return val;
+    return StringValue(val);
 }
 
-char* StdoutFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* StdoutFn(const char* name, State* state, int argc, Expr* argv[]) {
     int i;
     for (i = 0; i < argc; ++i) {
         char* v = Evaluate(state, argv[i]);
@@ -154,48 +181,44 @@ char* StdoutFn(const char* name, State* state, int argc, Expr* argv[]) {
         fputs(v, stdout);
         free(v);
     }
-    return strdup("");
+    return StringValue(strdup(""));
 }
 
-char* LogicalAndFn(const char* name, State* state,
+Value* LogicalAndFn(const char* name, State* state,
                    int argc, Expr* argv[]) {
     char* left = Evaluate(state, argv[0]);
     if (left == NULL) return NULL;
     if (BooleanString(left) == true) {
         free(left);
-        return Evaluate(state, argv[1]);
+        return EvaluateValue(state, argv[1]);
     } else {
-        return left;
+        return StringValue(left);
     }
 }
 
-char* LogicalOrFn(const char* name, State* state,
-                  int argc, Expr* argv[]) {
+Value* LogicalOrFn(const char* name, State* state,
+                   int argc, Expr* argv[]) {
     char* left = Evaluate(state, argv[0]);
     if (left == NULL) return NULL;
     if (BooleanString(left) == false) {
         free(left);
-        return Evaluate(state, argv[1]);
+        return EvaluateValue(state, argv[1]);
     } else {
-        return left;
+        return StringValue(left);
     }
 }
 
-char* LogicalNotFn(const char* name, State* state,
-                   int argc, Expr* argv[]) {
+Value* LogicalNotFn(const char* name, State* state,
+                    int argc, Expr* argv[]) {
     char* val = Evaluate(state, argv[0]);
     if (val == NULL) return NULL;
     bool bv = BooleanString(val);
     free(val);
-    if (bv) {
-        return strdup("");
-    } else {
-        return strdup("t");
-    }
+    return StringValue(strdup(bv ? "" : "t"));
 }
 
-char* SubstringFn(const char* name, State* state,
-                  int argc, Expr* argv[]) {
+Value* SubstringFn(const char* name, State* state,
+                   int argc, Expr* argv[]) {
     char* needle = Evaluate(state, argv[0]);
     if (needle == NULL) return NULL;
     char* haystack = Evaluate(state, argv[1]);
@@ -207,10 +230,10 @@ char* SubstringFn(const char* name, State* state,
     char* result = strdup(strstr(haystack, needle) ? "t" : "");
     free(needle);
     free(haystack);
-    return result;
+    return StringValue(result);
 }
 
-char* EqualityFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* EqualityFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* left = Evaluate(state, argv[0]);
     if (left == NULL) return NULL;
     char* right = Evaluate(state, argv[1]);
@@ -222,10 +245,10 @@ char* EqualityFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = strdup(strcmp(left, right) == 0 ? "t" : "");
     free(left);
     free(right);
-    return result;
+    return StringValue(result);
 }
 
-char* InequalityFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* InequalityFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* left = Evaluate(state, argv[0]);
     if (left == NULL) return NULL;
     char* right = Evaluate(state, argv[1]);
@@ -237,17 +260,17 @@ char* InequalityFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = strdup(strcmp(left, right) != 0 ? "t" : "");
     free(left);
     free(right);
-    return result;
+    return StringValue(result);
 }
 
-char* SequenceFn(const char* name, State* state, int argc, Expr* argv[]) {
-    char* left = Evaluate(state, argv[0]);
+Value* SequenceFn(const char* name, State* state, int argc, Expr* argv[]) {
+    Value* left = EvaluateValue(state, argv[0]);
     if (left == NULL) return NULL;
-    free(left);
-    return Evaluate(state, argv[1]);
+    FreeValue(left);
+    return EvaluateValue(state, argv[1]);
 }
 
-char* LessThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* LessThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 2) {
         free(state->errmsg);
         state->errmsg = strdup("less_than_int expects 2 arguments");
@@ -278,10 +301,11 @@ char* LessThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
   done:
     free(left);
     free(right);
-    return strdup(result ? "t" : "");
+    return StringValue(strdup(result ? "t" : ""));
 }
 
-char* GreaterThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* GreaterThanIntFn(const char* name, State* state,
+                        int argc, Expr* argv[]) {
     if (argc != 2) {
         free(state->errmsg);
         state->errmsg = strdup("greater_than_int expects 2 arguments");
@@ -295,8 +319,8 @@ char* GreaterThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
     return LessThanIntFn(name, state, 2, temp);
 }
 
-char* Literal(const char* name, State* state, int argc, Expr* argv[]) {
-    return strdup(name);
+Value* Literal(const char* name, State* state, int argc, Expr* argv[]) {
+    return StringValue(strdup(name));
 }
 
 Expr* Build(Function fn, YYLTYPE loc, int count, ...) {
@@ -400,6 +424,32 @@ int ReadArgs(State* state, Expr* argv[], int count, ...) {
     return 0;
 }
 
+// Evaluate the expressions in argv, giving 'count' Value* (the ... is
+// zero or more Value** to put them in).  If any expression evaluates
+// to NULL, free the rest and return -1.  Return 0 on success.
+int ReadValueArgs(State* state, Expr* argv[], int count, ...) {
+    Value** args = malloc(count * sizeof(Value*));
+    va_list v;
+    va_start(v, count);
+    int i;
+    for (i = 0; i < count; ++i) {
+        args[i] = EvaluateValue(state, argv[i]);
+        if (args[i] == NULL) {
+            va_end(v);
+            int j;
+            for (j = 0; j < i; ++j) {
+                FreeValue(args[j]);
+            }
+            free(args);
+            return -1;
+        }
+        *(va_arg(v, Value**)) = args[i];
+    }
+    va_end(v);
+    free(args);
+    return 0;
+}
+
 // Evaluate the expressions in argv, returning an array of char*
 // results.  If any evaluate to NULL, free the rest and return NULL.
 // The caller is responsible for freeing the returned array and the
@@ -421,9 +471,30 @@ char** ReadVarArgs(State* state, int argc, Expr* argv[]) {
     return args;
 }
 
+// Evaluate the expressions in argv, returning an array of Value*
+// results.  If any evaluate to NULL, free the rest and return NULL.
+// The caller is responsible for freeing the returned array and the
+// Values it contains.
+Value** ReadValueVarArgs(State* state, int argc, Expr* argv[]) {
+    Value** args = (Value**)malloc(argc * sizeof(Value*));
+    int i = 0;
+    for (i = 0; i < argc; ++i) {
+        args[i] = EvaluateValue(state, argv[i]);
+        if (args[i] == NULL) {
+            int j;
+            for (j = 0; j < i; ++j) {
+                FreeValue(args[j]);
+            }
+            free(args);
+            return NULL;
+        }
+    }
+    return args;
+}
+
 // Use printf-style arguments to compose an error message to put into
 // *state.  Returns NULL.
-char* ErrorAbort(State* state, char* format, ...) {
+Value* ErrorAbort(State* state, char* format, ...) {
     char* buffer = malloc(4096);
     va_list v;
     va_start(v, format);
diff --git a/edify/expr.h b/edify/expr.h
index d2e7392..1462531 100644
--- a/edify/expr.h
+++ b/edify/expr.h
@@ -39,8 +39,17 @@ typedef struct {
     char* errmsg;
 } State;
 
-typedef char* (*Function)(const char* name, State* state,
-                          int argc, Expr* argv[]);
+#define VAL_STRING  1  // data will be NULL-terminated; size doesn't count null
+#define VAL_BLOB    2
+
+typedef struct {
+    int type;
+    ssize_t size;
+    char* data;
+} Value;
+
+typedef Value* (*Function)(const char* name, State* state,
+                           int argc, Expr* argv[]);
 
 struct Expr {
     Function fn;
@@ -50,31 +59,41 @@ struct Expr {
     int start, end;
 };
 
+// Take one of the Expr*s passed to the function as an argument,
+// evaluate it, return the resulting Value.  The caller takes
+// ownership of the returned Value.
+Value* EvaluateValue(State* state, Expr* expr);
+
+// Take one of the Expr*s passed to the function as an argument,
+// evaluate it, assert that it is a string, and return the resulting
+// char*.  The caller takes ownership of the returned char*.  This is
+// a convenience function for older functions that want to deal only
+// with strings.
 char* Evaluate(State* state, Expr* expr);
 
 // Glue to make an Expr out of a literal.
-char* Literal(const char* name, State* state, int argc, Expr* argv[]);
+Value* Literal(const char* name, State* state, int argc, Expr* argv[]);
 
 // Functions corresponding to various syntactic sugar operators.
 // ("concat" is also available as a builtin function, to concatenate
 // more than two strings.)
-char* ConcatFn(const char* name, State* state, int argc, Expr* argv[]);
-char* LogicalAndFn(const char* name, State* state, int argc, Expr* argv[]);
-char* LogicalOrFn(const char* name, State* state, int argc, Expr* argv[]);
-char* LogicalNotFn(const char* name, State* state, int argc, Expr* argv[]);
-char* SubstringFn(const char* name, State* state, int argc, Expr* argv[]);
-char* EqualityFn(const char* name, State* state, int argc, Expr* argv[]);
-char* InequalityFn(const char* name, State* state, int argc, Expr* argv[]);
-char* SequenceFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* ConcatFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* LogicalAndFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* LogicalOrFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* LogicalNotFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* SubstringFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* EqualityFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* InequalityFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* SequenceFn(const char* name, State* state, int argc, Expr* argv[]);
 
 // Convenience function for building expressions with a fixed number
 // of arguments.
 Expr* Build(Function fn, YYLTYPE loc, int count, ...);
 
 // Global builtins, registered by RegisterBuiltins().
-char* IfElseFn(const char* name, State* state, int argc, Expr* argv[]);
-char* AssertFn(const char* name, State* state, int argc, Expr* argv[]);
-char* AbortFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* IfElseFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* AssertFn(const char* name, State* state, int argc, Expr* argv[]);
+Value* AbortFn(const char* name, State* state, int argc, Expr* argv[]);
 
 
 // For setting and getting the global error string (when returning
@@ -112,15 +131,31 @@ Function FindFunction(const char* name);
 // to NULL, free the rest and return -1.  Return 0 on success.
 int ReadArgs(State* state, Expr* argv[], int count, ...);
 
+// Evaluate the expressions in argv, giving 'count' Value* (the ... is
+// zero or more Value** to put them in).  If any expression evaluates
+// to NULL, free the rest and return -1.  Return 0 on success.
+int ReadValueArgs(State* state, Expr* argv[], int count, ...);
+
 // Evaluate the expressions in argv, returning an array of char*
 // results.  If any evaluate to NULL, free the rest and return NULL.
 // The caller is responsible for freeing the returned array and the
 // strings it contains.
 char** ReadVarArgs(State* state, int argc, Expr* argv[]);
 
+// Evaluate the expressions in argv, returning an array of Value*
+// results.  If any evaluate to NULL, free the rest and return NULL.
+// The caller is responsible for freeing the returned array and the
+// Values it contains.
+Value** ReadValueVarArgs(State* state, int argc, Expr* argv[]);
+
 // Use printf-style arguments to compose an error message to put into
 // *state.  Returns NULL.
-char* ErrorAbort(State* state, char* format, ...);
+Value* ErrorAbort(State* state, char* format, ...);
+
+// Wrap a string into a Value, taking ownership of the string.
+Value* StringValue(char* str);
 
+// Free a Value object.
+void FreeValue(Value* v);
 
 #endif  // _EXPRESSION_H
diff --git a/updater/install.c b/updater/install.c
index 852b393..2ffb384 100644
--- a/updater/install.c
+++ b/updater/install.c
@@ -29,17 +29,18 @@
 #include "cutils/misc.h"
 #include "cutils/properties.h"
 #include "edify/expr.h"
+#include "mincrypt/sha.h"
 #include "minzip/DirUtil.h"
 #include "mtdutils/mounts.h"
 #include "mtdutils/mtdutils.h"
 #include "updater.h"
-
+#include "applypatch/applypatch.h"
 
 // mount(type, location, mount_point)
 //
 //   what:  type="MTD"   location="<partition>"            to mount a yaffs2 filesystem
 //          type="vfat"  location="/dev/block/<whatever>"  to mount a device
-char* MountFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* MountFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     if (argc != 3) {
         return ErrorAbort(state, "%s() expects 3 args, got %d", name, argc);
@@ -98,12 +99,12 @@ done:
     free(type);
     free(location);
     if (result != mount_point) free(mount_point);
-    return result;
+    return StringValue(result);
 }
 
 
 // is_mounted(mount_point)
-char* IsMountedFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* IsMountedFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     if (argc != 1) {
         return ErrorAbort(state, "%s() expects 1 arg, got %d", name, argc);
@@ -127,11 +128,11 @@ char* IsMountedFn(const char* name, State* state, int argc, Expr* argv[]) {
 
 done:
     if (result != mount_point) free(mount_point);
-    return result;
+    return StringValue(result);
 }
 
 
-char* UnmountFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* UnmountFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     if (argc != 1) {
         return ErrorAbort(state, "%s() expects 1 arg, got %d", name, argc);
@@ -157,14 +158,14 @@ char* UnmountFn(const char* name, State* state, int argc, Expr* argv[]) {
 
 done:
     if (result != mount_point) free(mount_point);
-    return result;
+    return StringValue(result);
 }
 
 
 // format(type, location)
 //
 //    type="MTD"  location=partition
-char* FormatFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* FormatFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     if (argc != 2) {
         return ErrorAbort(state, "%s() expects 2 args, got %d", name, argc);
@@ -218,11 +219,11 @@ char* FormatFn(const char* name, State* state, int argc, Expr* argv[]) {
 done:
     free(type);
     if (result != location) free(location);
-    return result;
+    return StringValue(result);
 }
 
 
-char* DeleteFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* DeleteFn(const char* name, State* state, int argc, Expr* argv[]) {
     char** paths = malloc(argc * sizeof(char*));
     int i;
     for (i = 0; i < argc; ++i) {
@@ -249,11 +250,11 @@ char* DeleteFn(const char* name, State* state, int argc, Expr* argv[]) {
 
     char buffer[10];
     sprintf(buffer, "%d", success);
-    return strdup(buffer);
+    return StringValue(strdup(buffer));
 }
 
 
-char* ShowProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* ShowProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 2) {
         return ErrorAbort(state, "%s() expects 2 args, got %d", name, argc);
     }
@@ -270,10 +271,10 @@ char* ShowProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
     fprintf(ui->cmd_pipe, "progress %f %d\n", frac, sec);
 
     free(sec_str);
-    return frac_str;
+    return StringValue(frac_str);
 }
 
-char* SetProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* SetProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 1) {
         return ErrorAbort(state, "%s() expects 1 arg, got %d", name, argc);
     }
@@ -287,11 +288,11 @@ char* SetProgressFn(const char* name, State* state, int argc, Expr* argv[]) {
     UpdaterInfo* ui = (UpdaterInfo*)(state->cookie);
     fprintf(ui->cmd_pipe, "set_progress %f\n", frac);
 
-    return frac_str;
+    return StringValue(frac_str);
 }
 
 // package_extract_dir(package_path, destination_path)
-char* PackageExtractDirFn(const char* name, State* state,
+Value* PackageExtractDirFn(const char* name, State* state,
                           int argc, Expr* argv[]) {
     if (argc != 2) {
         return ErrorAbort(state, "%s() expects 2 args, got %d", name, argc);
@@ -310,7 +311,7 @@ char* PackageExtractDirFn(const char* name, State* state,
                                       NULL, NULL);
     free(zip_path);
     free(dest_path);
-    return strdup(success ? "t" : "");
+    return StringValue(strdup(success ? "t" : ""));
 }
 
 
@@ -318,9 +319,8 @@ char* PackageExtractDirFn(const char* name, State* state,
 //   or
 // package_extract_file(package_path)
 //   to return the entire contents of the file as the result of this
-//   function (the char* returned points to a long giving the length
-//   followed by that many bytes of data).
-char* PackageExtractFileFn(const char* name, State* state,
+//   function (the char* returned is actually a FileContents*).
+Value* PackageExtractFileFn(const char* name, State* state,
                            int argc, Expr* argv[]) {
     if (argc != 1 && argc != 2) {
         return ErrorAbort(state, "%s() expects 1 or 2 args, got %d",
@@ -353,13 +353,16 @@ char* PackageExtractFileFn(const char* name, State* state,
       done2:
         free(zip_path);
         free(dest_path);
-        return strdup(success ? "t" : "");
+        return StringValue(strdup(success ? "t" : ""));
     } else {
         // The one-argument version returns the contents of the file
         // as the result.
 
         char* zip_path;
-        char* buffer = NULL;
+        Value* v = malloc(sizeof(Value));
+        v->type = VAL_BLOB;
+        v->size = -1;
+        v->data = NULL;
 
         if (ReadArgs(state, argv, 1, &zip_path) < 0) return NULL;
 
@@ -370,33 +373,32 @@ char* PackageExtractFileFn(const char* name, State* state,
             goto done1;
         }
 
-        long size = mzGetZipEntryUncompLen(entry);
-        buffer = malloc(size + sizeof(long));
-        if (buffer == NULL) {
+        v->size = mzGetZipEntryUncompLen(entry);
+        v->data = malloc(v->size);
+        if (v->data == NULL) {
             fprintf(stderr, "%s: failed to allocate %ld bytes for %s\n",
-                    name, size+sizeof(long), zip_path);
+                    name, (long)v->size, zip_path);
             goto done1;
         }
 
-        *(long *)buffer = size;
-        success = mzExtractZipEntryToBuffer(
-            za, entry, (unsigned char *)(buffer + sizeof(long)));
+        success = mzExtractZipEntryToBuffer(za, entry,
+                                            (unsigned char *)v->data);
 
       done1:
         free(zip_path);
         if (!success) {
-            free(buffer);
-            buffer = malloc(sizeof(long));
-            *(long *)buffer = -1L;
+            free(v->data);
+            v->data = NULL;
+            v->size = -1;
         }
-        return buffer;
+        return v;
     }
 }
 
 
 // symlink target src1 src2 ...
 //    unlinks any previously existing src1, src2, etc before creating symlinks.
-char* SymlinkFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* SymlinkFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc == 0) {
         return ErrorAbort(state, "%s() expects 1+ args, got %d", name, argc);
     }
@@ -425,11 +427,11 @@ char* SymlinkFn(const char* name, State* state, int argc, Expr* argv[]) {
         free(srcs[i]);
     }
     free(srcs);
-    return strdup("");
+    return StringValue(strdup(""));
 }
 
 
-char* SetPermFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* SetPermFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     bool recursive = (strcmp(name, "set_perm_recursive") == 0);
 
@@ -499,11 +501,11 @@ done:
     }
     free(args);
 
-    return result;
+    return StringValue(result);
 }
 
 
-char* GetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* GetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 1) {
         return ErrorAbort(state, "%s() expects 1 arg, got %d", name, argc);
     }
@@ -515,7 +517,7 @@ char* GetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
     property_get(key, value, "");
     free(key);
 
-    return strdup(value);
+    return StringValue(strdup(value));
 }
 
 
@@ -524,7 +526,7 @@ char* GetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
 //   interprets 'file' as a getprop-style file (key=value pairs, one
 //   per line, # comment lines and blank lines okay), and returns the value
 //   for 'key' (or "" if it isn't defined).
-char* FileGetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* FileGetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
     char* buffer = NULL;
     char* filename;
@@ -614,7 +616,7 @@ char* FileGetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
     free(filename);
     free(key);
     free(buffer);
-    return result;
+    return StringValue(result);
 }
 
 
@@ -627,7 +629,7 @@ static bool write_raw_image_cb(const unsigned char* data,
 }
 
 // write_raw_image(file, partition)
-char* WriteRawImageFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* WriteRawImageFn(const char* name, State* state, int argc, Expr* argv[]) {
     char* result = NULL;
 
     char* partition;
@@ -700,15 +702,13 @@ char* WriteRawImageFn(const char* name, State* state, int argc, Expr* argv[]) {
 done:
     if (result != partition) free(partition);
     free(filename);
-    return result;
+    return StringValue(result);
 }
 
-extern int applypatch(int argc, char** argv);
-
 // apply_patch(srcfile, tgtfile, tgtsha1, tgtsize, sha1:patch, ...)
 // apply_patch_check(file, sha1, ...)
 // apply_patch_space(bytes)
-char* ApplyPatchFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* ApplyPatchFn(const char* name, State* state, int argc, Expr* argv[]) {
     printf("in applypatchfn (%s)\n", name);
 
     char* prepend = NULL;
@@ -747,13 +747,13 @@ char* ApplyPatchFn(const char* name, State* state, int argc, Expr* argv[]) {
     free(args);
 
     switch (result) {
-        case 0:   return strdup("t");
-        case 1:   return strdup("");
+        case 0:   return StringValue(strdup("t"));
+        case 1:   return StringValue(strdup(""));
         default:  return ErrorAbort(state, "applypatch couldn't parse args");
     }
 }
 
-char* UIPrintFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* UIPrintFn(const char* name, State* state, int argc, Expr* argv[]) {
     char** args = ReadVarArgs(state, argc, argv);
     if (args == NULL) {
         return NULL;
@@ -782,10 +782,10 @@ char* UIPrintFn(const char* name, State* state, int argc, Expr* argv[]) {
     }
     fprintf(((UpdaterInfo*)(state->cookie))->cmd_pipe, "ui_print\n");
 
-    return buffer;
+    return StringValue(buffer);
 }
 
-char* RunProgramFn(const char* name, State* state, int argc, Expr* argv[]) {
+Value* RunProgramFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc < 1) {
         return ErrorAbort(state, "%s() expects at least 1 arg", name);
     }
@@ -828,9 +828,138 @@ char* RunProgramFn(const char* name, State* state, int argc, Expr* argv[]) {
     char buffer[20];
     sprintf(buffer, "%d", status);
 
-    return strdup(buffer);
+    return StringValue(strdup(buffer));
 }
 
+// Take a string 'str' of 40 hex digits and parse it into the 20
+// byte array 'digest'.  'str' may contain only the digest or be of
+// the form "<digest>:<anything>".  Return 0 on success, -1 on any
+// error.
+static int ParseSha1(const char* str, uint8_t* digest) {
+  int i;
+  const char* ps = str;
+  uint8_t* pd = digest;
+  for (i = 0; i < SHA_DIGEST_SIZE * 2; ++i, ++ps) {
+    int digit;
+    if (*ps >= '0' && *ps <= '9') {
+      digit = *ps - '0';
+    } else if (*ps >= 'a' && *ps <= 'f') {
+      digit = *ps - 'a' + 10;
+    } else if (*ps >= 'A' && *ps <= 'F') {
+      digit = *ps - 'A' + 10;
+    } else {
+      return -1;
+    }
+    if (i % 2 == 0) {
+      *pd = digit << 4;
+    } else {
+      *pd |= digit;
+      ++pd;
+    }
+  }
+  if (*ps != '\0') return -1;
+  return 0;
+}
+
+// Take a sha-1 digest and return it as a newly-allocated hex string.
+static char* PrintSha1(uint8_t* digest) {
+    char* buffer = malloc(SHA_DIGEST_SIZE*2 + 1);
+    int i;
+    const char* alphabet = "0123456789abcdef";
+    for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+        buffer[i*2] = alphabet[(digest[i] >> 4) & 0xf];
+        buffer[i*2+1] = alphabet[digest[i] & 0xf];
+    }
+    buffer[i*2] = '\0';
+    return buffer;
+}
+
+// sha1_check(data)
+//    to return the sha1 of the data (given in the format returned by
+//    read_file).
+//
+// sha1_check(data, sha1_hex, [sha1_hex, ...])
+//    returns the sha1 of the file if it matches any of the hex
+//    strings passed, or "" if it does not equal any of them.
+//
+Value* Sha1CheckFn(const char* name, State* state, int argc, Expr* argv[]) {
+    if (argc < 1) {
+        return ErrorAbort(state, "%s() expects at least 1 arg", name);
+    }
+
+    Value** args = ReadValueVarArgs(state, argc, argv);
+    if (args == NULL) {
+        return NULL;
+    }
+
+    if (args[0]->size < 0) {
+        fprintf(stderr, "%s(): no file contents received", name);
+        return StringValue(strdup(""));
+    }
+    uint8_t digest[SHA_DIGEST_SIZE];
+    SHA(args[0]->data, args[0]->size, digest);
+    FreeValue(args[0]);
+
+    if (argc == 1) {
+        return StringValue(PrintSha1(digest));
+    }
+
+    int i;
+    uint8_t* arg_digest = malloc(SHA_DIGEST_SIZE);
+    for (i = 1; i < argc; ++i) {
+        if (args[i]->type != VAL_STRING) {
+            fprintf(stderr, "%s(): arg %d is not a string; skipping",
+                    name, i);
+        } else if (ParseSha1(args[i]->data, arg_digest) != 0) {
+            // Warn about bad args and skip them.
+            fprintf(stderr, "%s(): error parsing \"%s\" as sha-1; skipping",
+                    name, args[i]->data);
+        } else if (memcmp(digest, arg_digest, SHA_DIGEST_SIZE) == 0) {
+            break;
+        }
+        FreeValue(args[i]);
+    }
+    if (i >= argc) {
+        // Didn't match any of the hex strings; return false.
+        return StringValue(strdup(""));
+    }
+    // Found a match; free all the remaining arguments and return the
+    // matched one.
+    int j;
+    for (j = i+1; j < argc; ++j) {
+        FreeValue(args[j]);
+    }
+    return args[i];
+}
+
+// Read a local file and return its contents (the char* returned
+// is actually a FileContents*).
+Value* ReadFileFn(const char* name, State* state, int argc, Expr* argv[]) {
+    if (argc != 1) {
+        return ErrorAbort(state, "%s() expects 1 arg, got %d", name, argc);
+    }
+    char* filename;
+    if (ReadArgs(state, argv, 1, &filename) < 0) return NULL;
+
+    Value* v = malloc(sizeof(Value));
+    v->type = VAL_BLOB;
+
+    FileContents fc;
+    if (LoadFileContents(filename, &fc) != 0) {
+        ErrorAbort(state, "%s() loading \"%s\" failed: %s",
+                   name, filename, strerror(errno));
+        free(filename);
+        free(v);
+        free(fc.data);
+        return NULL;
+    }
+
+    v->size = fc.size;
+    v->data = (char*)fc.data;
+
+    free(filename);
+    return v;
+}
 
 void RegisterInstallFunctions() {
     RegisterFunction("mount", MountFn);
@@ -855,6 +984,9 @@ void RegisterInstallFunctions() {
     RegisterFunction("apply_patch_check", ApplyPatchFn);
     RegisterFunction("apply_patch_space", ApplyPatchFn);
 
+    RegisterFunction("read_file", ReadFileFn);
+    RegisterFunction("sha1_check", Sha1CheckFn);
+
     RegisterFunction("ui_print", UIPrintFn);
 
     RegisterFunction("run_program", RunProgramFn);
diff --git a/updater/updater.c b/updater/updater.c
index 2d16dee..6537a94 100644
--- a/updater/updater.c
+++ b/updater/updater.c
@@ -33,6 +33,12 @@
 #define SCRIPT_NAME "META-INF/com/google/android/updater-script"
 
 int main(int argc, char** argv) {
+    // Various things log information to stdout or stderr more or less
+    // at random.  The log file makes more sense if buffering is
+    // turned off so things appear in the right order.
+    setbuf(stdout, NULL);
+    setbuf(stderr, NULL);
+
     if (argc != 4) {
         fprintf(stderr, "unexpected number of arguments (%d)\n", argc);
         return 1;