Complete update of zlib from 1.2.3 to 1.2.5.

You may think that https://codereview.chromium.org/8806004 , back in
2011, did this. However, that's not correct. That update only patched files which
were present in both our old, customized checkout and zlib 1.2.5.

In zlib 1.2.5, gzio.c was replaced with gzclose.c, gzguts.h, gzlib.c, gzread.c
and gzwrite.c. We did not add those files. We just used the gzio.c from 1.2.3
with our custom patches from Gears, together with the rest of 1.2.5.

This unholy chimera worked until I went ahead and tried to fix the broken
mangling for 64 bit API symbols. See
https://codereview.chromium.org/13473020/ . This uncovered the lack of
gzread64, which was, after that fix, referenced by libxml. Since gzio.c from
1.2.3 doesn't have gzread64, this was something of a problem. I'm thus
finishing the update.

R=agl@chromium.org,rsleevi@chromium.org,brettw@chromium.org,bradchen@chromium.org
BUG=None

Review URL: https://chromiumcodereview.appspot.com/13564004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193127 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 1909 insertions, 1036 deletions

diff --git a/third_party/zlib/google.patch b/third_party/zlib/google.patch
index 1c59bec..e2bc2a0 100644
--- a/third_party/zlib/google.patch
+++ b/third_party/zlib/google.patch
@@ -1,3 +1,17 @@
+diff -ru zlib-1.2.5/gzlib.c zlib/gzlib.c
+--- zlib-1.2.5/gzlib.c
++++ zlib/gzlib.c
+@@ -5,7 +5,9 @@
+ 
+ #include "gzguts.h"
+ 
+-#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
++#if defined(_WIN32)
++#  define LSEEK _lseeki64
++#elif defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
+ #  define LSEEK lseek64
+ #else
+ #  define LSEEK lseek
 diff -ru zlib-1.2.5/mozzconf.h zlib/mozzconf.h
 --- zlib-1.2.5/mozzconf.h	2011-12-15 18:10:49.000000000 +0800
 +++ zlib/mozzconf.h	2011-12-16 16:08:00.000000000 +0800
@@ -183,7 +197,15 @@ diff -ru zlib-1.2.5/zconf.h zlib/zconf.h
  /*
   * If you *really* need a unique prefix for all types and library functions,
   * compile with -DZ_PREFIX. The "standard" zlib should be compiled without it.
-diff -ru zlib-1.2.5/zlib.h zlib/zlib.h
+@@ -359,7 +359,7 @@ typedef uLong FAR uLongf;
+    typedef Byte       *voidp;
+ #endif
+ 
+-#ifdef HAVE_UNISTD_H    /* may be set to #if 1 by ./configure */
++#if !defined(_WIN32)
+ #  define Z_HAVE_UNISTD_H
+ #endif
+ 
 --- zlib-1.2.5/zlib.h	2010-04-20 12:12:48.000000000 +0800
 +++ zlib/zlib.h	2011-12-16 16:08:48.000000000 +0800
 @@ -1572,12 +1572,14 @@
diff --git a/third_party/zlib/gzclose.c b/third_party/zlib/gzclose.c
new file mode 100644
index 0000000..caeb99a
--- /dev/null
+++ b/third_party/zlib/gzclose.c
@@ -0,0 +1,25 @@
+/* gzclose.c -- zlib gzclose() function
+ * Copyright (C) 2004, 2010 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "gzguts.h"
+
+/* gzclose() is in a separate file so that it is linked in only if it is used.
+   That way the other gzclose functions can be used instead to avoid linking in
+   unneeded compression or decompression routines. */
+int ZEXPORT gzclose(file)
+    gzFile file;
+{
+#ifndef NO_GZCOMPRESS
+    gz_statep state;
+
+    if (file == NULL)
+        return Z_STREAM_ERROR;
+    state = (gz_statep)file;
+
+    return state->mode == GZ_READ ? gzclose_r(file) : gzclose_w(file);
+#else
+    return gzclose_r(file);
+#endif
+}
diff --git a/third_party/zlib/gzguts.h b/third_party/zlib/gzguts.h
new file mode 100644
index 0000000..0f8fb79
--- /dev/null
+++ b/third_party/zlib/gzguts.h
@@ -0,0 +1,132 @@
+/* gzguts.h -- zlib internal header definitions for gz* operations
+ * Copyright (C) 2004, 2005, 2010 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#ifdef _LARGEFILE64_SOURCE
+#  ifndef _LARGEFILE_SOURCE
+#    define _LARGEFILE_SOURCE 1
+#  endif
+#  ifdef _FILE_OFFSET_BITS
+#    undef _FILE_OFFSET_BITS
+#  endif
+#endif
+
+#if ((__GNUC__-0) * 10 + __GNUC_MINOR__-0 >= 33) && !defined(NO_VIZ)
+#  define ZLIB_INTERNAL __attribute__((visibility ("hidden")))
+#else
+#  define ZLIB_INTERNAL
+#endif
+
+#include <stdio.h>
+#include "zlib.h"
+#ifdef STDC
+#  include <string.h>
+#  include <stdlib.h>
+#  include <limits.h>
+#endif
+#include <fcntl.h>
+
+#ifdef NO_DEFLATE       /* for compatibility with old definition */
+#  define NO_GZCOMPRESS
+#endif
+
+#ifdef _MSC_VER
+#  include <io.h>
+#  define vsnprintf _vsnprintf
+#endif
+
+#ifndef local
+#  define local static
+#endif
+/* compile with -Dlocal if your debugger can't find static symbols */
+
+/* gz* functions always use library allocation functions */
+#ifndef STDC
+  extern voidp  malloc OF((uInt size));
+  extern void   free   OF((voidpf ptr));
+#endif
+
+/* get errno and strerror definition */
+#if defined UNDER_CE
+#  include <windows.h>
+#  define zstrerror() gz_strwinerror((DWORD)GetLastError())
+#else
+#  ifdef STDC
+#    include <errno.h>
+#    define zstrerror() strerror(errno)
+#  else
+#    define zstrerror() "stdio error (consult errno)"
+#  endif
+#endif
+
+/* provide prototypes for these when building zlib without LFS */
+#if !defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0
+    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
+    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
+    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
+    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
+#endif
+
+/* default i/o buffer size -- double this for output when reading */
+#define GZBUFSIZE 8192
+
+/* gzip modes, also provide a little integrity check on the passed structure */
+#define GZ_NONE 0
+#define GZ_READ 7247
+#define GZ_WRITE 31153
+#define GZ_APPEND 1     /* mode set to GZ_WRITE after the file is opened */
+
+/* values for gz_state how */
+#define LOOK 0      /* look for a gzip header */
+#define COPY 1      /* copy input directly */
+#define GZIP 2      /* decompress a gzip stream */
+
+/* internal gzip file state data structure */
+typedef struct {
+        /* used for both reading and writing */
+    int mode;               /* see gzip modes above */
+    int fd;                 /* file descriptor */
+    char *path;             /* path or fd for error messages */
+    z_off64_t pos;          /* current position in uncompressed data */
+    unsigned size;          /* buffer size, zero if not allocated yet */
+    unsigned want;          /* requested buffer size, default is GZBUFSIZE */
+    unsigned char *in;      /* input buffer */
+    unsigned char *out;     /* output buffer (double-sized when reading) */
+    unsigned char *next;    /* next output data to deliver or write */
+        /* just for reading */
+    unsigned have;          /* amount of output data unused at next */
+    int eof;                /* true if end of input file reached */
+    z_off64_t start;        /* where the gzip data started, for rewinding */
+    z_off64_t raw;          /* where the raw data started, for seeking */
+    int how;                /* 0: get header, 1: copy, 2: decompress */
+    int direct;             /* true if last read direct, false if gzip */
+        /* just for writing */
+    int level;              /* compression level */
+    int strategy;           /* compression strategy */
+        /* seek request */
+    z_off64_t skip;         /* amount to skip (already rewound if backwards) */
+    int seek;               /* true if seek request pending */
+        /* error information */
+    int err;                /* error code */
+    char *msg;              /* error message */
+        /* zlib inflate or deflate stream */
+    z_stream strm;          /* stream structure in-place (not a pointer) */
+} gz_state;
+typedef gz_state FAR *gz_statep;
+
+/* shared functions */
+void ZLIB_INTERNAL gz_error OF((gz_statep, int, const char *));
+#if defined UNDER_CE
+char ZLIB_INTERNAL *gz_strwinerror OF((DWORD error));
+#endif
+
+/* GT_OFF(x), where x is an unsigned value, is true if x > maximum z_off64_t
+   value -- needed when comparing unsigned to z_off64_t, which is signed
+   (possible z_off64_t types off_t, off64_t, and long are all signed) */
+#ifdef INT_MAX
+#  define GT_OFF(x) (sizeof(int) == sizeof(z_off64_t) && (x) > INT_MAX)
+#else
+unsigned ZLIB_INTERNAL gz_intmax OF((void));
+#  define GT_OFF(x) (sizeof(int) == sizeof(z_off64_t) && (x) > gz_intmax())
+#endif
diff --git a/third_party/zlib/gzio.c b/third_party/zlib/gzio.c
deleted file mode 100644
index b5f052c..0000000
--- a/third_party/zlib/gzio.c
+++ /dev/null
@@ -1,1033 +0,0 @@
-/* gzio.c -- IO on .gz files
- * Copyright (C) 1995-2005 Jean-loup Gailly.
- * For conditions of distribution and use, see copyright notice in zlib.h
- *
- * Compile this file with -DNO_GZCOMPRESS to avoid the compression code.
- */
-
-/* @(#) $Id: gzio.c,v 3.7 2005/08/04 19:14:14 tor%cs.brown.edu Exp $ */
-
-#include <stdio.h>
-
-#include "zutil.h"
-
-#ifdef NO_DEFLATE       /* for compatibility with old definition */
-#  define NO_GZCOMPRESS
-#endif
-
-#ifndef NO_DUMMY_DECL
-struct internal_state {int dummy;}; /* for buggy compilers */
-#endif
-
-#ifndef Z_BUFSIZE
-#  ifdef MAXSEG_64K
-#    define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
-#  else
-#    define Z_BUFSIZE 16384
-#  endif
-#endif
-#ifndef Z_PRINTF_BUFSIZE
-#  define Z_PRINTF_BUFSIZE 4096
-#endif
-
-#ifdef __MVS__
-#  pragma map (fdopen , "\174\174FDOPEN")
-   FILE *fdopen(int, const char *);
-#endif
-
-#ifndef STDC
-extern voidp  malloc OF((uInt size));
-extern void   free   OF((voidpf ptr));
-#endif
-
-#define ALLOC(size) malloc(size)
-#define TRYFREE(p) {if (p) free(p);}
-
-static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
-
-/* gzip flag byte */
-#define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
-#define HEAD_CRC     0x02 /* bit 1 set: header CRC present */
-#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
-#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
-#define COMMENT      0x10 /* bit 4 set: file comment present */
-#define RESERVED     0xE0 /* bits 5..7: reserved */
-
-typedef struct gz_stream {
-    z_stream stream;
-    int      z_err;   /* error code for last stream operation */
-    int      z_eof;   /* set if end of input file */
-    FILE     *file;   /* .gz file */
-    Byte     *inbuf;  /* input buffer */
-    Byte     *outbuf; /* output buffer */
-    uLong    crc;     /* crc32 of uncompressed data */
-    char     *msg;    /* error message */
-    char     *path;   /* path name for debugging only */
-    int      transparent; /* 1 if input file is not a .gz file */
-    char     mode;    /* 'w' or 'r' */
-    z_off_t  start;   /* start of compressed data in file (header skipped) */
-    z_off_t  in;      /* bytes into deflate or inflate */
-    z_off_t  out;     /* bytes out of deflate or inflate */
-    int      back;    /* one character push-back */
-    int      last;    /* true if push-back is last character */
-} gz_stream;
-
-
-local gzFile gz_open      OF((const char *path, const char *mode, int  fd));
-#ifndef NO_GZCOMPRESS  // Google Gears addition, to avoid compile warning
-local int do_flush        OF((gzFile file, int flush));
-#endif
-local int    get_byte     OF((gz_stream *s));
-local void   check_header OF((gz_stream *s));
-local int    destroy      OF((gz_stream *s));
-#ifndef NO_GZCOMPRESS  // Google Gears addition, to avoid compile warning
-local void   putLong      OF((FILE *file, uLong x));
-#endif
-local uLong  getLong      OF((gz_stream *s));
-
-/* ===========================================================================
-     Opens a gzip (.gz) file for reading or writing. The mode parameter
-   is as in fopen ("rb" or "wb"). The file is given either by file descriptor
-   or path name (if fd == -1).
-     gz_open returns NULL if the file could not be opened or if there was
-   insufficient memory to allocate the (de)compression state; errno
-   can be checked to distinguish the two cases (if errno is zero, the
-   zlib error is Z_MEM_ERROR).
-*/
-local gzFile gz_open (path, mode, fd)
-    const char *path;
-    const char *mode;
-    int  fd;
-{
-    int err;
-    int level = Z_DEFAULT_COMPRESSION; /* compression level */
-    int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
-    char *p = (char*)mode;
-    gz_stream *s;
-    char fmode[80]; /* copy of mode, without the compression level */
-    char *m = fmode;
-
-    if (!path || !mode) return Z_NULL;
-
-    s = (gz_stream *)ALLOC(sizeof(gz_stream));
-    if (!s) return Z_NULL;
-
-    s->stream.zalloc = (alloc_func)0;
-    s->stream.zfree = (free_func)0;
-    s->stream.opaque = (voidpf)0;
-    s->stream.next_in = s->inbuf = Z_NULL;
-    s->stream.next_out = s->outbuf = Z_NULL;
-    s->stream.avail_in = s->stream.avail_out = 0;
-    s->file = NULL;
-    s->z_err = Z_OK;
-    s->z_eof = 0;
-    s->in = 0;
-    s->out = 0;
-    s->back = EOF;
-    s->crc = crc32(0L, Z_NULL, 0);
-    s->msg = NULL;
-    s->transparent = 0;
-
-    s->path = (char*)ALLOC(strlen(path)+1);
-    if (s->path == NULL) {
-        return destroy(s), (gzFile)Z_NULL;
-    }
-    strcpy(s->path, path); /* do this early for debugging */
-
-    s->mode = '\0';
-    do {
-        if (*p == 'r') s->mode = 'r';
-        if (*p == 'w' || *p == 'a') s->mode = 'w';
-        if (*p >= '0' && *p <= '9') {
-            level = *p - '0';
-        } else if (*p == 'f') {
-          strategy = Z_FILTERED;
-        } else if (*p == 'h') {
-          strategy = Z_HUFFMAN_ONLY;
-        } else if (*p == 'R') {
-          strategy = Z_RLE;
-        } else {
-            *m++ = *p; /* copy the mode */
-        }
-    } while (*p++ && m != fmode + sizeof(fmode));
-    if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
-
-    if (s->mode == 'w') {
-#ifdef NO_GZCOMPRESS
-        err = Z_STREAM_ERROR;
-#else
-        err = deflateInit2(&(s->stream), level,
-                           Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
-        /* windowBits is passed < 0 to suppress zlib header */
-
-        s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
-#endif
-        if (err != Z_OK || s->outbuf == Z_NULL) {
-            return destroy(s), (gzFile)Z_NULL;
-        }
-    } else {
-        s->stream.next_in  = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
-
-        err = inflateInit2(&(s->stream), -MAX_WBITS);
-        /* windowBits is passed < 0 to tell that there is no zlib header.
-         * Note that in this case inflate *requires* an extra "dummy" byte
-         * after the compressed stream in order to complete decompression and
-         * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
-         * present after the compressed stream.
-         */
-        if (err != Z_OK || s->inbuf == Z_NULL) {
-            return destroy(s), (gzFile)Z_NULL;
-        }
-    }
-    s->stream.avail_out = Z_BUFSIZE;
-
-    errno = 0;
-    s->file = fd < 0 ? F_OPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
-
-    if (s->file == NULL) {
-        return destroy(s), (gzFile)Z_NULL;
-    }
-    if (s->mode == 'w') {
-        /* Write a very simple .gz header:
-         */
-        fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
-             Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
-        s->start = 10L;
-        /* We use 10L instead of ftell(s->file) to because ftell causes an
-         * fflush on some systems. This version of the library doesn't use
-         * start anyway in write mode, so this initialization is not
-         * necessary.
-         */
-    } else {
-        check_header(s); /* skip the .gz header */
-        s->start = ftell(s->file) - s->stream.avail_in;
-    }
-
-    return (gzFile)s;
-}
-
-/* ===========================================================================
-     Opens a gzip (.gz) file for reading or writing.
-*/
-gzFile ZEXPORT gzopen (path, mode)
-    const char *path;
-    const char *mode;
-{
-    return gz_open (path, mode, -1);
-}
-
-/* ===========================================================================
-     Associate a gzFile with the file descriptor fd. fd is not dup'ed here
-   to mimic the behavio(u)r of fdopen.
-*/
-gzFile ZEXPORT gzdopen (fd, mode)
-    int fd;
-    const char *mode;
-{
-    char name[46];      /* allow for up to 128-bit integers */
-
-    if (fd < 0) return (gzFile)Z_NULL;
-    sprintf(name, "<fd:%d>", fd); /* for debugging */
-
-    return gz_open (name, mode, fd);
-}
-
-/* ===========================================================================
- * Update the compression level and strategy
- */
-int ZEXPORT gzsetparams (file, level, strategy)
-    gzFile file;
-    int level;
-    int strategy;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
-
-    /* Make room to allow flushing */
-    if (s->stream.avail_out == 0) {
-
-        s->stream.next_out = s->outbuf;
-        if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
-            s->z_err = Z_ERRNO;
-        }
-        s->stream.avail_out = Z_BUFSIZE;
-    }
-
-    return deflateParams (&(s->stream), level, strategy);
-}
-
-/* ===========================================================================
-     Read a byte from a gz_stream; update next_in and avail_in. Return EOF
-   for end of file.
-   IN assertion: the stream s has been sucessfully opened for reading.
-*/
-local int get_byte(s)
-    gz_stream *s;
-{
-    if (s->z_eof) return EOF;
-    if (s->stream.avail_in == 0) {
-        errno = 0;
-        s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
-        if (s->stream.avail_in == 0) {
-            s->z_eof = 1;
-            if (ferror(s->file)) s->z_err = Z_ERRNO;
-            return EOF;
-        }
-        s->stream.next_in = s->inbuf;
-    }
-    s->stream.avail_in--;
-    return *(s->stream.next_in)++;
-}
-
-/* ===========================================================================
-      Check the gzip header of a gz_stream opened for reading. Set the stream
-    mode to transparent if the gzip magic header is not present; set s->err
-    to Z_DATA_ERROR if the magic header is present but the rest of the header
-    is incorrect.
-    IN assertion: the stream s has already been created sucessfully;
-       s->stream.avail_in is zero for the first time, but may be non-zero
-       for concatenated .gz files.
-*/
-local void check_header(s)
-    gz_stream *s;
-{
-    int method; /* method byte */
-    int flags;  /* flags byte */
-    uInt len;
-    int c;
-
-    /* Assure two bytes in the buffer so we can peek ahead -- handle case
-       where first byte of header is at the end of the buffer after the last
-       gzip segment */
-    len = s->stream.avail_in;
-    if (len < 2) {
-        if (len) s->inbuf[0] = s->stream.next_in[0];
-        errno = 0;
-        len = (uInt)fread(s->inbuf + len, 1, Z_BUFSIZE >> len, s->file);
-        if (len == 0 && ferror(s->file)) s->z_err = Z_ERRNO;
-        s->stream.avail_in += len;
-        s->stream.next_in = s->inbuf;
-        if (s->stream.avail_in < 2) {
-            s->transparent = s->stream.avail_in;
-            return;
-        }
-    }
-
-    /* Peek ahead to check the gzip magic header */
-    if (s->stream.next_in[0] != gz_magic[0] ||
-        s->stream.next_in[1] != gz_magic[1]) {
-        s->transparent = 1;
-        return;
-    }
-    s->stream.avail_in -= 2;
-    s->stream.next_in += 2;
-
-    /* Check the rest of the gzip header */
-    method = get_byte(s);
-    flags = get_byte(s);
-    if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
-        s->z_err = Z_DATA_ERROR;
-        return;
-    }
-
-    /* Discard time, xflags and OS code: */
-    for (len = 0; len < 6; len++) (void)get_byte(s);
-
-    if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
-        len  =  (uInt)get_byte(s);
-        len += ((uInt)get_byte(s))<<8;
-        /* len is garbage if EOF but the loop below will quit anyway */
-        while (len-- != 0 && get_byte(s) != EOF) ;
-    }
-    if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
-        while ((c = get_byte(s)) != 0 && c != EOF) ;
-    }
-    if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
-        while ((c = get_byte(s)) != 0 && c != EOF) ;
-    }
-    if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
-        for (len = 0; len < 2; len++) (void)get_byte(s);
-    }
-    s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
-}
-
- /* ===========================================================================
- * Cleanup then free the given gz_stream. Return a zlib error code.
-   Try freeing in the reverse order of allocations.
- */
-local int destroy (s)
-    gz_stream *s;
-{
-    int err = Z_OK;
-
-    if (!s) return Z_STREAM_ERROR;
-
-    TRYFREE(s->msg);
-
-    if (s->stream.state != NULL) {
-        if (s->mode == 'w') {
-#ifdef NO_GZCOMPRESS
-            err = Z_STREAM_ERROR;
-#else
-            err = deflateEnd(&(s->stream));
-#endif
-        } else if (s->mode == 'r') {
-            err = inflateEnd(&(s->stream));
-        }
-    }
-    if (s->file != NULL && fclose(s->file)) {
-#ifdef ESPIPE
-        if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */
-#endif
-            err = Z_ERRNO;
-    }
-    if (s->z_err < 0) err = s->z_err;
-
-    TRYFREE(s->inbuf);
-    TRYFREE(s->outbuf);
-    TRYFREE(s->path);
-    TRYFREE(s);
-    return err;
-}
-
-/* ===========================================================================
-     Reads the given number of uncompressed bytes from the compressed file.
-   gzread returns the number of bytes actually read (0 for end of file).
-*/
-int ZEXPORT gzread (file, buf, len)
-    gzFile file;
-    voidp buf;
-    unsigned len;
-{
-    gz_stream *s = (gz_stream*)file;
-    Bytef *start = (Bytef*)buf; /* starting point for crc computation */
-    Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
-
-    if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
-
-    if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
-    if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
-
-    next_out = (Byte*)buf;
-    s->stream.next_out = (Bytef*)buf;
-    s->stream.avail_out = len;
-
-    if (s->stream.avail_out && s->back != EOF) {
-        *next_out++ = s->back;
-        s->stream.next_out++;
-        s->stream.avail_out--;
-        s->back = EOF;
-        s->out++;
-        start++;
-        if (s->last) {
-            s->z_err = Z_STREAM_END;
-            return 1;
-        }
-    }
-
-    while (s->stream.avail_out != 0) {
-
-        if (s->transparent) {
-            /* Copy first the lookahead bytes: */
-            uInt n = s->stream.avail_in;
-            if (n > s->stream.avail_out) n = s->stream.avail_out;
-            if (n > 0) {
-                zmemcpy(s->stream.next_out, s->stream.next_in, n);
-                next_out += n;
-                s->stream.next_out = next_out;
-                s->stream.next_in   += n;
-                s->stream.avail_out -= n;
-                s->stream.avail_in  -= n;
-            }
-            if (s->stream.avail_out > 0) {
-                s->stream.avail_out -=
-                    (uInt)fread(next_out, 1, s->stream.avail_out, s->file);
-            }
-            len -= s->stream.avail_out;
-            s->in  += len;
-            s->out += len;
-            if (len == 0) s->z_eof = 1;
-            return (int)len;
-        }
-        if (s->stream.avail_in == 0 && !s->z_eof) {
-
-            errno = 0;
-            s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
-            if (s->stream.avail_in == 0) {
-                s->z_eof = 1;
-                if (ferror(s->file)) {
-                    s->z_err = Z_ERRNO;
-                    break;
-                }
-            }
-            s->stream.next_in = s->inbuf;
-        }
-        s->in += s->stream.avail_in;
-        s->out += s->stream.avail_out;
-        s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
-        s->in -= s->stream.avail_in;
-        s->out -= s->stream.avail_out;
-
-        if (s->z_err == Z_STREAM_END) {
-            /* Check CRC and original size */
-            s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
-            start = s->stream.next_out;
-
-            if (getLong(s) != s->crc) {
-                s->z_err = Z_DATA_ERROR;
-            } else {
-                (void)getLong(s);
-                /* The uncompressed length returned by above getlong() may be
-                 * different from s->out in case of concatenated .gz files.
-                 * Check for such files:
-                 */
-                check_header(s);
-                if (s->z_err == Z_OK) {
-                    inflateReset(&(s->stream));
-                    s->crc = crc32(0L, Z_NULL, 0);
-                }
-            }
-        }
-        if (s->z_err != Z_OK || s->z_eof) break;
-    }
-    s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
-
-    if (len == s->stream.avail_out &&
-        (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO))
-        return -1;
-    return (int)(len - s->stream.avail_out);
-}
-
-
-/* ===========================================================================
-      Reads one byte from the compressed file. gzgetc returns this byte
-   or -1 in case of end of file or error.
-*/
-int ZEXPORT gzgetc(file)
-    gzFile file;
-{
-    unsigned char c;
-
-    return gzread(file, &c, 1) == 1 ? c : -1;
-}
-
-
-/* ===========================================================================
-      Push one byte back onto the stream.
-*/
-int ZEXPORT gzungetc(c, file)
-    int c;
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'r' || c == EOF || s->back != EOF) return EOF;
-    s->back = c;
-    s->out--;
-    s->last = (s->z_err == Z_STREAM_END);
-    if (s->last) s->z_err = Z_OK;
-    s->z_eof = 0;
-    return c;
-}
-
-
-/* ===========================================================================
-      Reads bytes from the compressed file until len-1 characters are
-   read, or a newline character is read and transferred to buf, or an
-   end-of-file condition is encountered.  The string is then terminated
-   with a null character.
-      gzgets returns buf, or Z_NULL in case of error.
-
-      The current implementation is not optimized at all.
-*/
-char * ZEXPORT gzgets(file, buf, len)
-    gzFile file;
-    char *buf;
-    int len;
-{
-    char *b = buf;
-    if (buf == Z_NULL || len <= 0) return Z_NULL;
-
-    while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
-    *buf = '\0';
-    return b == buf && len > 0 ? Z_NULL : b;
-}
-
-
-#ifndef NO_GZCOMPRESS
-/* ===========================================================================
-     Writes the given number of uncompressed bytes into the compressed file.
-   gzwrite returns the number of bytes actually written (0 in case of error).
-*/
-int ZEXPORT gzwrite (file, buf, len)
-    gzFile file;
-    voidpc buf;
-    unsigned len;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
-
-    s->stream.next_in = (Bytef*)buf;
-    s->stream.avail_in = len;
-
-    while (s->stream.avail_in != 0) {
-
-        if (s->stream.avail_out == 0) {
-
-            s->stream.next_out = s->outbuf;
-            if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
-                s->z_err = Z_ERRNO;
-                break;
-            }
-            s->stream.avail_out = Z_BUFSIZE;
-        }
-        s->in += s->stream.avail_in;
-        s->out += s->stream.avail_out;
-        s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
-        s->in -= s->stream.avail_in;
-        s->out -= s->stream.avail_out;
-        if (s->z_err != Z_OK) break;
-    }
-    s->crc = crc32(s->crc, (const Bytef *)buf, len);
-
-    return (int)(len - s->stream.avail_in);
-}
-
-
-/* ===========================================================================
-     Converts, formats, and writes the args to the compressed file under
-   control of the format string, as in fprintf. gzprintf returns the number of
-   uncompressed bytes actually written (0 in case of error).
-*/
-#ifdef STDC
-#include <stdarg.h>
-
-int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
-{
-    char buf[Z_PRINTF_BUFSIZE];
-    va_list va;
-    int len;
-
-    buf[sizeof(buf) - 1] = 0;
-    va_start(va, format);
-#ifdef NO_vsnprintf
-#  ifdef HAS_vsprintf_void
-    (void)vsprintf(buf, format, va);
-    va_end(va);
-    for (len = 0; len < sizeof(buf); len++)
-        if (buf[len] == 0) break;
-#  else
-    len = vsprintf(buf, format, va);
-    va_end(va);
-#  endif
-#else
-#  ifdef HAS_vsnprintf_void
-    (void)vsnprintf(buf, sizeof(buf), format, va);
-    va_end(va);
-    len = strlen(buf);
-#  else
-    len = vsnprintf(buf, sizeof(buf), format, va);
-    va_end(va);
-#  endif
-#endif
-    if (len <= 0 || len >= (int)sizeof(buf) || buf[sizeof(buf) - 1] != 0)
-        return 0;
-    return gzwrite(file, buf, (unsigned)len);
-}
-#else /* not ANSI C */
-
-int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
-                       a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
-    gzFile file;
-    const char *format;
-    int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
-        a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
-{
-    char buf[Z_PRINTF_BUFSIZE];
-    int len;
-
-    buf[sizeof(buf) - 1] = 0;
-#ifdef NO_snprintf
-#  ifdef HAS_sprintf_void
-    sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
-            a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
-    for (len = 0; len < sizeof(buf); len++)
-        if (buf[len] == 0) break;
-#  else
-    len = sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
-                a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
-#  endif
-#else
-#  ifdef HAS_snprintf_void
-    snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
-             a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
-    len = strlen(buf);
-#  else
-    len = snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
-                 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
-#  endif
-#endif
-    if (len <= 0 || len >= sizeof(buf) || buf[sizeof(buf) - 1] != 0)
-        return 0;
-    return gzwrite(file, buf, len);
-}
-#endif
-
-/* ===========================================================================
-      Writes c, converted to an unsigned char, into the compressed file.
-   gzputc returns the value that was written, or -1 in case of error.
-*/
-int ZEXPORT gzputc(file, c)
-    gzFile file;
-    int c;
-{
-    unsigned char cc = (unsigned char) c; /* required for big endian systems */
-
-    return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
-}
-
-
-/* ===========================================================================
-      Writes the given null-terminated string to the compressed file, excluding
-   the terminating null character.
-      gzputs returns the number of characters written, or -1 in case of error.
-*/
-int ZEXPORT gzputs(file, s)
-    gzFile file;
-    const char *s;
-{
-    return gzwrite(file, (char*)s, (unsigned)strlen(s));
-}
-
-
-/* ===========================================================================
-     Flushes all pending output into the compressed file. The parameter
-   flush is as in the deflate() function.
-*/
-local int do_flush (file, flush)
-    gzFile file;
-    int flush;
-{
-    uInt len;
-    int done = 0;
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
-
-    s->stream.avail_in = 0; /* should be zero already anyway */
-
-    for (;;) {
-        len = Z_BUFSIZE - s->stream.avail_out;
-
-        if (len != 0) {
-            if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
-                s->z_err = Z_ERRNO;
-                return Z_ERRNO;
-            }
-            s->stream.next_out = s->outbuf;
-            s->stream.avail_out = Z_BUFSIZE;
-        }
-        if (done) break;
-        s->out += s->stream.avail_out;
-        s->z_err = deflate(&(s->stream), flush);
-        s->out -= s->stream.avail_out;
-
-        /* Ignore the second of two consecutive flushes: */
-        if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;
-
-        /* deflate has finished flushing only when it hasn't used up
-         * all the available space in the output buffer:
-         */
-        done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
-
-        if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
-    }
-    return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
-}
-
-int ZEXPORT gzflush (file, flush)
-     gzFile file;
-     int flush;
-{
-    gz_stream *s = (gz_stream*)file;
-    int err = do_flush (file, flush);
-
-    if (err) return err;
-    fflush(s->file);
-    return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
-}
-#endif /* NO_GZCOMPRESS */
-
-/* ===========================================================================
-      Sets the starting position for the next gzread or gzwrite on the given
-   compressed file. The offset represents a number of bytes in the
-      gzseek returns the resulting offset location as measured in bytes from
-   the beginning of the uncompressed stream, or -1 in case of error.
-      SEEK_END is not implemented, returns error.
-      In this version of the library, gzseek can be extremely slow.
-*/
-z_off_t ZEXPORT gzseek (file, offset, whence)
-    gzFile file;
-    z_off_t offset;
-    int whence;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || whence == SEEK_END ||
-        s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
-        return -1L;
-    }
-
-    if (s->mode == 'w') {
-#ifdef NO_GZCOMPRESS
-        return -1L;
-#else
-        if (whence == SEEK_SET) {
-            offset -= s->in;
-        }
-        if (offset < 0) return -1L;
-
-        /* At this point, offset is the number of zero bytes to write. */
-        if (s->inbuf == Z_NULL) {
-            s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
-            if (s->inbuf == Z_NULL) return -1L;
-            zmemzero(s->inbuf, Z_BUFSIZE);
-        }
-        while (offset > 0)  {
-            uInt size = Z_BUFSIZE;
-            if (offset < Z_BUFSIZE) size = (uInt)offset;
-
-            size = gzwrite(file, s->inbuf, size);
-            if (size == 0) return -1L;
-
-            offset -= size;
-        }
-        return s->in;
-#endif
-    }
-    /* Rest of function is for reading only */
-
-    /* compute absolute position */
-    if (whence == SEEK_CUR) {
-        offset += s->out;
-    }
-    if (offset < 0) return -1L;
-
-    if (s->transparent) {
-        /* map to fseek */
-        s->back = EOF;
-        s->stream.avail_in = 0;
-        s->stream.next_in = s->inbuf;
-        if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;
-
-        s->in = s->out = offset;
-        return offset;
-    }
-
-    /* For a negative seek, rewind and use positive seek */
-    if (offset >= s->out) {
-        offset -= s->out;
-    } else if (gzrewind(file) < 0) {
-        return -1L;
-    }
-    /* offset is now the number of bytes to skip. */
-
-    if (offset != 0 && s->outbuf == Z_NULL) {
-        s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
-        if (s->outbuf == Z_NULL) return -1L;
-    }
-    if (offset && s->back != EOF) {
-        s->back = EOF;
-        s->out++;
-        offset--;
-        if (s->last) s->z_err = Z_STREAM_END;
-    }
-    while (offset > 0)  {
-        int size = Z_BUFSIZE;
-        if (offset < Z_BUFSIZE) size = (int)offset;
-
-        size = gzread(file, s->outbuf, (uInt)size);
-        if (size <= 0) return -1L;
-        offset -= size;
-    }
-    return s->out;
-}
-
-/* ===========================================================================
-     Rewinds input file.
-*/
-int ZEXPORT gzrewind (file)
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'r') return -1;
-
-    s->z_err = Z_OK;
-    s->z_eof = 0;
-    s->back = EOF;
-    s->stream.avail_in = 0;
-    s->stream.next_in = s->inbuf;
-    s->crc = crc32(0L, Z_NULL, 0);
-    if (!s->transparent) (void)inflateReset(&s->stream);
-    s->in = 0;
-    s->out = 0;
-    return fseek(s->file, s->start, SEEK_SET);
-}
-
-/* ===========================================================================
-     Returns the starting position for the next gzread or gzwrite on the
-   given compressed file. This position represents a number of bytes in the
-   uncompressed data stream.
-*/
-z_off_t ZEXPORT gztell (file)
-    gzFile file;
-{
-    return gzseek(file, 0L, SEEK_CUR);
-}
-
-/* ===========================================================================
-     Returns 1 when EOF has previously been detected reading the given
-   input stream, otherwise zero.
-*/
-int ZEXPORT gzeof (file)
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    /* With concatenated compressed files that can have embedded
-     * crc trailers, z_eof is no longer the only/best indicator of EOF
-     * on a gz_stream. Handle end-of-stream error explicitly here.
-     */
-    if (s == NULL || s->mode != 'r') return 0;
-    if (s->z_eof) return 1;
-    return s->z_err == Z_STREAM_END;
-}
-
-/* ===========================================================================
-     Returns 1 if reading and doing so transparently, otherwise zero.
-*/
-int ZEXPORT gzdirect (file)
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL || s->mode != 'r') return 0;
-    return s->transparent;
-}
-
-#ifndef NO_GZCOMPRESS  // Google Gears addition, to avoid compile warning
-/* ===========================================================================
-   Outputs a long in LSB order to the given file
-*/
-local void putLong (file, x)
-    FILE *file;
-    uLong x;
-{
-    int n;
-    for (n = 0; n < 4; n++) {
-        fputc((int)(x & 0xff), file);
-        x >>= 8;
-    }
-}
-#endif
-
-/* ===========================================================================
-   Reads a long in LSB order from the given gz_stream. Sets z_err in case
-   of error.
-*/
-local uLong getLong (s)
-    gz_stream *s;
-{
-    uLong x = (uLong)get_byte(s);
-    int c;
-
-    x += ((uLong)get_byte(s))<<8;
-    x += ((uLong)get_byte(s))<<16;
-    c = get_byte(s);
-    if (c == EOF) s->z_err = Z_DATA_ERROR;
-    x += ((uLong)c)<<24;
-    return x;
-}
-
-/* ===========================================================================
-     Flushes all pending output if necessary, closes the compressed file
-   and deallocates all the (de)compression state.
-*/
-int ZEXPORT gzclose (file)
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL) return Z_STREAM_ERROR;
-
-    if (s->mode == 'w') {
-#ifdef NO_GZCOMPRESS
-        return Z_STREAM_ERROR;
-#else
-        if (do_flush (file, Z_FINISH) != Z_OK)
-            return destroy((gz_stream*)file);
-
-        putLong (s->file, s->crc);
-        putLong (s->file, (uLong)(s->in & 0xffffffff));
-#endif
-    }
-    return destroy((gz_stream*)file);
-}
-
-// Google Gears modification: strerror is not present on WinCE.
-#if defined(STDC) && !defined(_WIN32_WCE)
-#  define zstrerror(errnum) strerror(errnum)
-#else
-#  define zstrerror(errnum) ""
-#endif
-
-/* ===========================================================================
-     Returns the error message for the last error which occurred on the
-   given compressed file. errnum is set to zlib error number. If an
-   error occurred in the file system and not in the compression library,
-   errnum is set to Z_ERRNO and the application may consult errno
-   to get the exact error code.
-*/
-const char * ZEXPORT gzerror (file, errnum)
-    gzFile file;
-    int *errnum;
-{
-    char *m;
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL) {
-        *errnum = Z_STREAM_ERROR;
-        return (const char*)ERR_MSG(Z_STREAM_ERROR);
-    }
-    *errnum = s->z_err;
-    if (*errnum == Z_OK) return (const char*)"";
-
-    m = (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);
-
-    if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);
-
-    TRYFREE(s->msg);
-    s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
-    if (s->msg == Z_NULL) return (const char*)ERR_MSG(Z_MEM_ERROR);
-    strcpy(s->msg, s->path);
-    strcat(s->msg, ": ");
-    strcat(s->msg, m);
-    return (const char*)s->msg;
-}
-
-/* ===========================================================================
-     Clear the error and end-of-file flags, and do the same for the real file.
-*/
-void ZEXPORT gzclearerr (file)
-    gzFile file;
-{
-    gz_stream *s = (gz_stream*)file;
-
-    if (s == NULL) return;
-    if (s->z_err != Z_STREAM_END) s->z_err = Z_OK;
-    s->z_eof = 0;
-    clearerr(s->file);
-}
diff --git a/third_party/zlib/gzlib.c b/third_party/zlib/gzlib.c
new file mode 100644
index 0000000..feffbb1
--- /dev/null
+++ b/third_party/zlib/gzlib.c
@@ -0,0 +1,539 @@
+/* gzlib.c -- zlib functions common to reading and writing gzip files
+ * Copyright (C) 2004, 2010 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "gzguts.h"
+
+#if defined(_WIN32) && !defined(__BORLANDC__)
+#  define LSEEK _lseeki64
+#elif defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
+#  define LSEEK lseek64
+#else
+#  define LSEEK lseek
+#endif
+
+/* Local functions */
+local void gz_reset OF((gz_statep));
+local gzFile gz_open OF((const char *, int, const char *));
+
+#if defined UNDER_CE
+
+/* Map the Windows error number in ERROR to a locale-dependent error message
+   string and return a pointer to it.  Typically, the values for ERROR come
+   from GetLastError.
+
+   The string pointed to shall not be modified by the application, but may be
+   overwritten by a subsequent call to gz_strwinerror
+
+   The gz_strwinerror function does not change the current setting of
+   GetLastError. */
+char ZLIB_INTERNAL *gz_strwinerror (error)
+     DWORD error;
+{
+    static char buf[1024];
+
+    wchar_t *msgbuf;
+    DWORD lasterr = GetLastError();
+    DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
+        | FORMAT_MESSAGE_ALLOCATE_BUFFER,
+        NULL,
+        error,
+        0, /* Default language */
+        (LPVOID)&msgbuf,
+        0,
+        NULL);
+    if (chars != 0) {
+        /* If there is an \r\n appended, zap it.  */
+        if (chars >= 2
+            && msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
+            chars -= 2;
+            msgbuf[chars] = 0;
+        }
+
+        if (chars > sizeof (buf) - 1) {
+            chars = sizeof (buf) - 1;
+            msgbuf[chars] = 0;
+        }
+
+        wcstombs(buf, msgbuf, chars + 1);
+        LocalFree(msgbuf);
+    }
+    else {
+        sprintf(buf, "unknown win32 error (%ld)", error);
+    }
+
+    SetLastError(lasterr);
+    return buf;
+}
+
+#endif /* UNDER_CE */
+
+/* Reset gzip file state */
+local void gz_reset(state)
+    gz_statep state;
+{
+    if (state->mode == GZ_READ) {   /* for reading ... */
+        state->have = 0;            /* no output data available */
+        state->eof = 0;             /* not at end of file */
+        state->how = LOOK;          /* look for gzip header */
+        state->direct = 1;          /* default for empty file */
+    }
+    state->seek = 0;                /* no seek request pending */
+    gz_error(state, Z_OK, NULL);    /* clear error */
+    state->pos = 0;                 /* no uncompressed data yet */
+    state->strm.avail_in = 0;       /* no input data yet */
+}
+
+/* Open a gzip file either by name or file descriptor. */
+local gzFile gz_open(path, fd, mode)
+    const char *path;
+    int fd;
+    const char *mode;
+{
+    gz_statep state;
+
+    /* allocate gzFile structure to return */
+    state = malloc(sizeof(gz_state));
+    if (state == NULL)
+        return NULL;
+    state->size = 0;            /* no buffers allocated yet */
+    state->want = GZBUFSIZE;    /* requested buffer size */
+    state->msg = NULL;          /* no error message yet */
+
+    /* interpret mode */
+    state->mode = GZ_NONE;
+    state->level = Z_DEFAULT_COMPRESSION;
+    state->strategy = Z_DEFAULT_STRATEGY;
+    while (*mode) {
+        if (*mode >= '0' && *mode <= '9')
+            state->level = *mode - '0';
+        else
+            switch (*mode) {
+            case 'r':
+                state->mode = GZ_READ;
+                break;
+#ifndef NO_GZCOMPRESS
+            case 'w':
+                state->mode = GZ_WRITE;
+                break;
+            case 'a':
+                state->mode = GZ_APPEND;
+                break;
+#endif
+            case '+':       /* can't read and write at the same time */
+                free(state);
+                return NULL;
+            case 'b':       /* ignore -- will request binary anyway */
+                break;
+            case 'f':
+                state->strategy = Z_FILTERED;
+                break;
+            case 'h':
+                state->strategy = Z_HUFFMAN_ONLY;
+                break;
+            case 'R':
+                state->strategy = Z_RLE;
+                break;
+            case 'F':
+                state->strategy = Z_FIXED;
+            default:        /* could consider as an error, but just ignore */
+                ;
+            }
+        mode++;
+    }
+
+    /* must provide an "r", "w", or "a" */
+    if (state->mode == GZ_NONE) {
+        free(state);
+        return NULL;
+    }
+
+    /* save the path name for error messages */
+    state->path = malloc(strlen(path) + 1);
+    if (state->path == NULL) {
+        free(state);
+        return NULL;
+    }
+    strcpy(state->path, path);
+
+    /* open the file with the appropriate mode (or just use fd) */
+    state->fd = fd != -1 ? fd :
+        open(path,
+#ifdef O_LARGEFILE
+            O_LARGEFILE |
+#endif
+#ifdef O_BINARY
+            O_BINARY |
+#endif
+            (state->mode == GZ_READ ?
+                O_RDONLY :
+                (O_WRONLY | O_CREAT | (
+                    state->mode == GZ_WRITE ?
+                        O_TRUNC :
+                        O_APPEND))),
+            0666);
+    if (state->fd == -1) {
+        free(state->path);
+        free(state);
+        return NULL;
+    }
+    if (state->mode == GZ_APPEND)
+        state->mode = GZ_WRITE;         /* simplify later checks */
+
+    /* save the current position for rewinding (only if reading) */
+    if (state->mode == GZ_READ) {
+        state->start = LSEEK(state->fd, 0, SEEK_CUR);
+        if (state->start == -1) state->start = 0;
+    }
+
+    /* initialize stream */
+    gz_reset(state);
+
+    /* return stream */
+    return (gzFile)state;
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzopen(path, mode)
+    const char *path;
+    const char *mode;
+{
+    return gz_open(path, -1, mode);
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzopen64(path, mode)
+    const char *path;
+    const char *mode;
+{
+    return gz_open(path, -1, mode);
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzdopen(fd, mode)
+    int fd;
+    const char *mode;
+{
+    char *path;         /* identifier for error messages */
+    gzFile gz;
+
+    if (fd == -1 || (path = malloc(7 + 3 * sizeof(int))) == NULL)
+        return NULL;
+    sprintf(path, "<fd:%d>", fd);   /* for debugging */
+    gz = gz_open(path, fd, mode);
+    free(path);
+    return gz;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzbuffer(file, size)
+    gzFile file;
+    unsigned size;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* make sure we haven't already allocated memory */
+    if (state->size != 0)
+        return -1;
+
+    /* check and set requested size */
+    if (size == 0)
+        return -1;
+    state->want = size;
+    return 0;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzrewind(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ || state->err != Z_OK)
+        return -1;
+
+    /* back up and start over */
+    if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
+        return -1;
+    gz_reset(state);
+    return 0;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gzseek64(file, offset, whence)
+    gzFile file;
+    z_off64_t offset;
+    int whence;
+{
+    unsigned n;
+    z_off64_t ret;
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* check that there's no error */
+    if (state->err != Z_OK)
+        return -1;
+
+    /* can only seek from start or relative to current position */
+    if (whence != SEEK_SET && whence != SEEK_CUR)
+        return -1;
+
+    /* normalize offset to a SEEK_CUR specification */
+    if (whence == SEEK_SET)
+        offset -= state->pos;
+    else if (state->seek)
+        offset += state->skip;
+    state->seek = 0;
+
+    /* if within raw area while reading, just go there */
+    if (state->mode == GZ_READ && state->how == COPY &&
+        state->pos + offset >= state->raw) {
+        ret = LSEEK(state->fd, offset - state->have, SEEK_CUR);
+        if (ret == -1)
+            return -1;
+        state->have = 0;
+        state->eof = 0;
+        state->seek = 0;
+        gz_error(state, Z_OK, NULL);
+        state->strm.avail_in = 0;
+        state->pos += offset;
+        return state->pos;
+    }
+
+    /* calculate skip amount, rewinding if needed for back seek when reading */
+    if (offset < 0) {
+        if (state->mode != GZ_READ)         /* writing -- can't go backwards */
+            return -1;
+        offset += state->pos;
+        if (offset < 0)                     /* before start of file! */
+            return -1;
+        if (gzrewind(file) == -1)           /* rewind, then skip to offset */
+            return -1;
+    }
+
+    /* if reading, skip what's in output buffer (one less gzgetc() check) */
+    if (state->mode == GZ_READ) {
+        n = GT_OFF(state->have) || (z_off64_t)state->have > offset ?
+            (unsigned)offset : state->have;
+        state->have -= n;
+        state->next += n;
+        state->pos += n;
+        offset -= n;
+    }
+
+    /* request skip (if not zero) */
+    if (offset) {
+        state->seek = 1;
+        state->skip = offset;
+    }
+    return state->pos + offset;
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gzseek(file, offset, whence)
+    gzFile file;
+    z_off_t offset;
+    int whence;
+{
+    z_off64_t ret;
+
+    ret = gzseek64(file, (z_off64_t)offset, whence);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gztell64(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* return position */
+    return state->pos + (state->seek ? state->skip : 0);
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gztell(file)
+    gzFile file;
+{
+    z_off64_t ret;
+
+    ret = gztell64(file);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gzoffset64(file)
+    gzFile file;
+{
+    z_off64_t offset;
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* compute and return effective offset in file */
+    offset = LSEEK(state->fd, 0, SEEK_CUR);
+    if (offset == -1)
+        return -1;
+    if (state->mode == GZ_READ)             /* reading */
+        offset -= state->strm.avail_in;     /* don't count buffered input */
+    return offset;
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gzoffset(file)
+    gzFile file;
+{
+    z_off64_t ret;
+
+    ret = gzoffset64(file);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzeof(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return 0;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return 0;
+
+    /* return end-of-file state */
+    return state->mode == GZ_READ ?
+        (state->eof && state->strm.avail_in == 0 && state->have == 0) : 0;
+}
+
+/* -- see zlib.h -- */
+const char * ZEXPORT gzerror(file, errnum)
+    gzFile file;
+    int *errnum;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return NULL;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return NULL;
+
+    /* return error information */
+    if (errnum != NULL)
+        *errnum = state->err;
+    return state->msg == NULL ? "" : state->msg;
+}
+
+/* -- see zlib.h -- */
+void ZEXPORT gzclearerr(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return;
+
+    /* clear error and end-of-file */
+    if (state->mode == GZ_READ)
+        state->eof = 0;
+    gz_error(state, Z_OK, NULL);
+}
+
+/* Create an error message in allocated memory and set state->err and
+   state->msg accordingly.  Free any previous error message already there.  Do
+   not try to free or allocate space if the error is Z_MEM_ERROR (out of
+   memory).  Simply save the error message as a static string.  If there is an
+   allocation failure constructing the error message, then convert the error to
+   out of memory. */
+void ZLIB_INTERNAL gz_error(state, err, msg)
+    gz_statep state;
+    int err;
+    const char *msg;
+{
+    /* free previously allocated message and clear */
+    if (state->msg != NULL) {
+        if (state->err != Z_MEM_ERROR)
+            free(state->msg);
+        state->msg = NULL;
+    }
+
+    /* set error code, and if no message, then done */
+    state->err = err;
+    if (msg == NULL)
+        return;
+
+    /* for an out of memory error, save as static string */
+    if (err == Z_MEM_ERROR) {
+        state->msg = (char *)msg;
+        return;
+    }
+
+    /* construct error message with path */
+    if ((state->msg = malloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {
+        state->err = Z_MEM_ERROR;
+        state->msg = (char *)"out of memory";
+        return;
+    }
+    strcpy(state->msg, state->path);
+    strcat(state->msg, ": ");
+    strcat(state->msg, msg);
+    return;
+}
+
+#ifndef INT_MAX
+/* portably return maximum value for an int (when limits.h presumed not
+   available) -- we need to do this to cover cases where 2's complement not
+   used, since C standard permits 1's complement and sign-bit representations,
+   otherwise we could just use ((unsigned)-1) >> 1 */
+unsigned ZLIB_INTERNAL gz_intmax()
+{
+    unsigned p, q;
+
+    p = 1;
+    do {
+        q = p;
+        p <<= 1;
+        p++;
+    } while (p > q);
+    return q >> 1;
+}
+#endif
diff --git a/third_party/zlib/gzread.c b/third_party/zlib/gzread.c
new file mode 100644
index 0000000..548201a
--- /dev/null
+++ b/third_party/zlib/gzread.c
@@ -0,0 +1,653 @@
+/* gzread.c -- zlib functions for reading gzip files
+ * Copyright (C) 2004, 2005, 2010 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "gzguts.h"
+
+/* Local functions */
+local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
+local int gz_avail OF((gz_statep));
+local int gz_next4 OF((gz_statep, unsigned long *));
+local int gz_head OF((gz_statep));
+local int gz_decomp OF((gz_statep));
+local int gz_make OF((gz_statep));
+local int gz_skip OF((gz_statep, z_off64_t));
+
+/* Use read() to load a buffer -- return -1 on error, otherwise 0.  Read from
+   state->fd, and update state->eof, state->err, and state->msg as appropriate.
+   This function needs to loop on read(), since read() is not guaranteed to
+   read the number of bytes requested, depending on the type of descriptor. */
+local int gz_load(state, buf, len, have)
+    gz_statep state;
+    unsigned char *buf;
+    unsigned len;
+    unsigned *have;
+{
+    int ret;
+
+    *have = 0;
+    do {
+        ret = read(state->fd, buf + *have, len - *have);
+        if (ret <= 0)
+            break;
+        *have += ret;
+    } while (*have < len);
+    if (ret < 0) {
+        gz_error(state, Z_ERRNO, zstrerror());
+        return -1;
+    }
+    if (ret == 0)
+        state->eof = 1;
+    return 0;
+}
+
+/* Load up input buffer and set eof flag if last data loaded -- return -1 on
+   error, 0 otherwise.  Note that the eof flag is set when the end of the input
+   file is reached, even though there may be unused data in the buffer.  Once
+   that data has been used, no more attempts will be made to read the file.
+   gz_avail() assumes that strm->avail_in == 0. */
+local int gz_avail(state)
+    gz_statep state;
+{
+    z_streamp strm = &(state->strm);
+
+    if (state->err != Z_OK)
+        return -1;
+    if (state->eof == 0) {
+        if (gz_load(state, state->in, state->size,
+                (unsigned *)&(strm->avail_in)) == -1)
+            return -1;
+        strm->next_in = state->in;
+    }
+    return 0;
+}
+
+/* Get next byte from input, or -1 if end or error. */
+#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \
+                (strm->avail_in == 0 ? -1 : \
+                 (strm->avail_in--, *(strm->next_in)++)))
+
+/* Get a four-byte little-endian integer and return 0 on success and the value
+   in *ret.  Otherwise -1 is returned and *ret is not modified. */
+local int gz_next4(state, ret)
+    gz_statep state;
+    unsigned long *ret;
+{
+    int ch;
+    unsigned long val;
+    z_streamp strm = &(state->strm);
+
+    val = NEXT();
+    val += (unsigned)NEXT() << 8;
+    val += (unsigned long)NEXT() << 16;
+    ch = NEXT();
+    if (ch == -1)
+        return -1;
+    val += (unsigned long)ch << 24;
+    *ret = val;
+    return 0;
+}
+
+/* Look for gzip header, set up for inflate or copy.  state->have must be zero.
+   If this is the first time in, allocate required memory.  state->how will be
+   left unchanged if there is no more input data available, will be set to COPY
+   if there is no gzip header and direct copying will be performed, or it will
+   be set to GZIP for decompression, and the gzip header will be skipped so
+   that the next available input data is the raw deflate stream.  If direct
+   copying, then leftover input data from the input buffer will be copied to
+   the output buffer.  In that case, all further file reads will be directly to
+   either the output buffer or a user buffer.  If decompressing, the inflate
+   state and the check value will be initialized.  gz_head() will return 0 on
+   success or -1 on failure.  Failures may include read errors or gzip header
+   errors.  */
+local int gz_head(state)
+    gz_statep state;
+{
+    z_streamp strm = &(state->strm);
+    int flags;
+    unsigned len;
+
+    /* allocate read buffers and inflate memory */
+    if (state->size == 0) {
+        /* allocate buffers */
+        state->in = malloc(state->want);
+        state->out = malloc(state->want << 1);
+        if (state->in == NULL || state->out == NULL) {
+            if (state->out != NULL)
+                free(state->out);
+            if (state->in != NULL)
+                free(state->in);
+            gz_error(state, Z_MEM_ERROR, "out of memory");
+            return -1;
+        }
+        state->size = state->want;
+
+        /* allocate inflate memory */
+        state->strm.zalloc = Z_NULL;
+        state->strm.zfree = Z_NULL;
+        state->strm.opaque = Z_NULL;
+        state->strm.avail_in = 0;
+        state->strm.next_in = Z_NULL;
+        if (inflateInit2(&(state->strm), -15) != Z_OK) {    /* raw inflate */
+            free(state->out);
+            free(state->in);
+            state->size = 0;
+            gz_error(state, Z_MEM_ERROR, "out of memory");
+            return -1;
+        }
+    }
+
+    /* get some data in the input buffer */
+    if (strm->avail_in == 0) {
+        if (gz_avail(state) == -1)
+            return -1;
+        if (strm->avail_in == 0)
+            return 0;
+    }
+
+    /* look for the gzip magic header bytes 31 and 139 */
+    if (strm->next_in[0] == 31) {
+        strm->avail_in--;
+        strm->next_in++;
+        if (strm->avail_in == 0 && gz_avail(state) == -1)
+            return -1;
+        if (strm->avail_in && strm->next_in[0] == 139) {
+            /* we have a gzip header, woo hoo! */
+            strm->avail_in--;
+            strm->next_in++;
+
+            /* skip rest of header */
+            if (NEXT() != 8) {      /* compression method */
+                gz_error(state, Z_DATA_ERROR, "unknown compression method");
+                return -1;
+            }
+            flags = NEXT();
+            if (flags & 0xe0) {     /* reserved flag bits */
+                gz_error(state, Z_DATA_ERROR, "unknown header flags set");
+                return -1;
+            }
+            NEXT();                 /* modification time */
+            NEXT();
+            NEXT();
+            NEXT();
+            NEXT();                 /* extra flags */
+            NEXT();                 /* operating system */
+            if (flags & 4) {        /* extra field */
+                len = (unsigned)NEXT();
+                len += (unsigned)NEXT() << 8;
+                while (len--)
+                    if (NEXT() < 0)
+                        break;
+            }
+            if (flags & 8)          /* file name */
+                while (NEXT() > 0)
+                    ;
+            if (flags & 16)         /* comment */
+                while (NEXT() > 0)
+                    ;
+            if (flags & 2) {        /* header crc */
+                NEXT();
+                NEXT();
+            }
+            /* an unexpected end of file is not checked for here -- it will be
+               noticed on the first request for uncompressed data */
+
+            /* set up for decompression */
+            inflateReset(strm);
+            strm->adler = crc32(0L, Z_NULL, 0);
+            state->how = GZIP;
+            state->direct = 0;
+            return 0;
+        }
+        else {
+            /* not a gzip file -- save first byte (31) and fall to raw i/o */
+            state->out[0] = 31;
+            state->have = 1;
+        }
+    }
+
+    /* doing raw i/o, save start of raw data for seeking, copy any leftover
+       input to output -- this assumes that the output buffer is larger than
+       the input buffer, which also assures space for gzungetc() */
+    state->raw = state->pos;
+    state->next = state->out;
+    if (strm->avail_in) {
+        memcpy(state->next + state->have, strm->next_in, strm->avail_in);
+        state->have += strm->avail_in;
+        strm->avail_in = 0;
+    }
+    state->how = COPY;
+    state->direct = 1;
+    return 0;
+}
+
+/* Decompress from input to the provided next_out and avail_out in the state.
+   If the end of the compressed data is reached, then verify the gzip trailer
+   check value and length (modulo 2^32).  state->have and state->next are set
+   to point to the just decompressed data, and the crc is updated.  If the
+   trailer is verified, state->how is reset to LOOK to look for the next gzip
+   stream or raw data, once state->have is depleted.  Returns 0 on success, -1
+   on failure.  Failures may include invalid compressed data or a failed gzip
+   trailer verification. */
+local int gz_decomp(state)
+    gz_statep state;
+{
+    int ret;
+    unsigned had;
+    unsigned long crc, len;
+    z_streamp strm = &(state->strm);
+
+    /* fill output buffer up to end of deflate stream */
+    had = strm->avail_out;
+    do {
+        /* get more input for inflate() */
+        if (strm->avail_in == 0 && gz_avail(state) == -1)
+            return -1;
+        if (strm->avail_in == 0) {
+            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
+            return -1;
+        }
+
+        /* decompress and handle errors */
+        ret = inflate(strm, Z_NO_FLUSH);
+        if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
+            gz_error(state, Z_STREAM_ERROR,
+                      "internal error: inflate stream corrupt");
+            return -1;
+        }
+        if (ret == Z_MEM_ERROR) {
+            gz_error(state, Z_MEM_ERROR, "out of memory");
+            return -1;
+        }
+        if (ret == Z_DATA_ERROR) {              /* deflate stream invalid */
+            gz_error(state, Z_DATA_ERROR,
+                      strm->msg == NULL ? "compressed data error" : strm->msg);
+            return -1;
+        }
+    } while (strm->avail_out && ret != Z_STREAM_END);
+
+    /* update available output and crc check value */
+    state->have = had - strm->avail_out;
+    state->next = strm->next_out - state->have;
+    strm->adler = crc32(strm->adler, state->next, state->have);
+
+    /* check gzip trailer if at end of deflate stream */
+    if (ret == Z_STREAM_END) {
+        if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
+            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
+            return -1;
+        }
+        if (crc != strm->adler) {
+            gz_error(state, Z_DATA_ERROR, "incorrect data check");
+            return -1;
+        }
+        if (len != (strm->total_out & 0xffffffffL)) {
+            gz_error(state, Z_DATA_ERROR, "incorrect length check");
+            return -1;
+        }
+        state->how = LOOK;      /* ready for next stream, once have is 0 (leave
+                                   state->direct unchanged to remember how) */
+    }
+
+    /* good decompression */
+    return 0;
+}
+
+/* Make data and put in the output buffer.  Assumes that state->have == 0.
+   Data is either copied from the input file or decompressed from the input
+   file depending on state->how.  If state->how is LOOK, then a gzip header is
+   looked for (and skipped if found) to determine wither to copy or decompress.
+   Returns -1 on error, otherwise 0.  gz_make() will leave state->have as COPY
+   or GZIP unless the end of the input file has been reached and all data has
+   been processed.  */
+local int gz_make(state)
+    gz_statep state;
+{
+    z_streamp strm = &(state->strm);
+
+    if (state->how == LOOK) {           /* look for gzip header */
+        if (gz_head(state) == -1)
+            return -1;
+        if (state->have)                /* got some data from gz_head() */
+            return 0;
+    }
+    if (state->how == COPY) {           /* straight copy */
+        if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1)
+            return -1;
+        state->next = state->out;
+    }
+    else if (state->how == GZIP) {      /* decompress */
+        strm->avail_out = state->size << 1;
+        strm->next_out = state->out;
+        if (gz_decomp(state) == -1)
+            return -1;
+    }
+    return 0;
+}
+
+/* Skip len uncompressed bytes of output.  Return -1 on error, 0 on success. */
+local int gz_skip(state, len)
+    gz_statep state;
+    z_off64_t len;
+{
+    unsigned n;
+
+    /* skip over len bytes or reach end-of-file, whichever comes first */
+    while (len)
+        /* skip over whatever is in output buffer */
+        if (state->have) {
+            n = GT_OFF(state->have) || (z_off64_t)state->have > len ?
+                (unsigned)len : state->have;
+            state->have -= n;
+            state->next += n;
+            state->pos += n;
+            len -= n;
+        }
+
+        /* output buffer empty -- return if we're at the end of the input */
+        else if (state->eof && state->strm.avail_in == 0)
+            break;
+
+        /* need more data to skip -- load up output buffer */
+        else {
+            /* get more output, looking for header if required */
+            if (gz_make(state) == -1)
+                return -1;
+        }
+    return 0;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzread(file, buf, len)
+    gzFile file;
+    voidp buf;
+    unsigned len;
+{
+    unsigned got, n;
+    gz_statep state;
+    z_streamp strm;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ || state->err != Z_OK)
+        return -1;
+
+    /* since an int is returned, make sure len fits in one, otherwise return
+       with an error (this avoids the flaw in the interface) */
+    if ((int)len < 0) {
+        gz_error(state, Z_BUF_ERROR, "requested length does not fit in int");
+        return -1;
+    }
+
+    /* if len is zero, avoid unnecessary operations */
+    if (len == 0)
+        return 0;
+
+    /* process a skip request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_skip(state, state->skip) == -1)
+            return -1;
+    }
+
+    /* get len bytes to buf, or less than len if at the end */
+    got = 0;
+    do {
+        /* first just try copying data from the output buffer */
+        if (state->have) {
+            n = state->have > len ? len : state->have;
+            memcpy(buf, state->next, n);
+            state->next += n;
+            state->have -= n;
+        }
+
+        /* output buffer empty -- return if we're at the end of the input */
+        else if (state->eof && strm->avail_in == 0)
+            break;
+
+        /* need output data -- for small len or new stream load up our output
+           buffer */
+        else if (state->how == LOOK || len < (state->size << 1)) {
+            /* get more output, looking for header if required */
+            if (gz_make(state) == -1)
+                return -1;
+            continue;       /* no progress yet -- go back to memcpy() above */
+            /* the copy above assures that we will leave with space in the
+               output buffer, allowing at least one gzungetc() to succeed */
+        }
+
+        /* large len -- read directly into user buffer */
+        else if (state->how == COPY) {      /* read directly */
+            if (gz_load(state, buf, len, &n) == -1)
+                return -1;
+        }
+
+        /* large len -- decompress directly into user buffer */
+        else {  /* state->how == GZIP */
+            strm->avail_out = len;
+            strm->next_out = buf;
+            if (gz_decomp(state) == -1)
+                return -1;
+            n = state->have;
+            state->have = 0;
+        }
+
+        /* update progress */
+        len -= n;
+        buf = (char *)buf + n;
+        got += n;
+        state->pos += n;
+    } while (len);
+
+    /* return number of bytes read into user buffer (will fit in int) */
+    return (int)got;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzgetc(file)
+    gzFile file;
+{
+    int ret;
+    unsigned char buf[1];
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ || state->err != Z_OK)
+        return -1;
+
+    /* try output buffer (no need to check for skip request) */
+    if (state->have) {
+        state->have--;
+        state->pos++;
+        return *(state->next)++;
+    }
+
+    /* nothing there -- try gzread() */
+    ret = gzread(file, buf, 1);
+    return ret < 1 ? -1 : buf[0];
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzungetc(c, file)
+    int c;
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ || state->err != Z_OK)
+        return -1;
+
+    /* process a skip request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_skip(state, state->skip) == -1)
+            return -1;
+    }
+
+    /* can't push EOF */
+    if (c < 0)
+        return -1;
+
+    /* if output buffer empty, put byte at end (allows more pushing) */
+    if (state->have == 0) {
+        state->have = 1;
+        state->next = state->out + (state->size << 1) - 1;
+        state->next[0] = c;
+        state->pos--;
+        return c;
+    }
+
+    /* if no room, give up (must have already done a gzungetc()) */
+    if (state->have == (state->size << 1)) {
+        gz_error(state, Z_BUF_ERROR, "out of room to push characters");
+        return -1;
+    }
+
+    /* slide output data if needed and insert byte before existing data */
+    if (state->next == state->out) {
+        unsigned char *src = state->out + state->have;
+        unsigned char *dest = state->out + (state->size << 1);
+        while (src > state->out)
+            *--dest = *--src;
+        state->next = dest;
+    }
+    state->have++;
+    state->next--;
+    state->next[0] = c;
+    state->pos--;
+    return c;
+}
+
+/* -- see zlib.h -- */
+char * ZEXPORT gzgets(file, buf, len)
+    gzFile file;
+    char *buf;
+    int len;
+{
+    unsigned left, n;
+    char *str;
+    unsigned char *eol;
+    gz_statep state;
+
+    /* check parameters and get internal structure */
+    if (file == NULL || buf == NULL || len < 1)
+        return NULL;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ || state->err != Z_OK)
+        return NULL;
+
+    /* process a skip request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_skip(state, state->skip) == -1)
+            return NULL;
+    }
+
+    /* copy output bytes up to new line or len - 1, whichever comes first --
+       append a terminating zero to the string (we don't check for a zero in
+       the contents, let the user worry about that) */
+    str = buf;
+    left = (unsigned)len - 1;
+    if (left) do {
+        /* assure that something is in the output buffer */
+        if (state->have == 0) {
+            if (gz_make(state) == -1)
+                return NULL;            /* error */
+            if (state->have == 0) {     /* end of file */
+                if (buf == str)         /* got bupkus */
+                    return NULL;
+                break;                  /* got something -- return it */
+            }
+        }
+
+        /* look for end-of-line in current output buffer */
+        n = state->have > left ? left : state->have;
+        eol = memchr(state->next, '\n', n);
+        if (eol != NULL)
+            n = (unsigned)(eol - state->next) + 1;
+
+        /* copy through end-of-line, or remainder if not found */
+        memcpy(buf, state->next, n);
+        state->have -= n;
+        state->next += n;
+        state->pos += n;
+        left -= n;
+        buf += n;
+    } while (left && eol == NULL);
+
+    /* found end-of-line or out of space -- terminate string and return it */
+    buf[0] = 0;
+    return str;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzdirect(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return 0;
+    state = (gz_statep)file;
+
+    /* check that we're reading */
+    if (state->mode != GZ_READ)
+        return 0;
+
+    /* if the state is not known, but we can find out, then do so (this is
+       mainly for right after a gzopen() or gzdopen()) */
+    if (state->how == LOOK && state->have == 0)
+        (void)gz_head(state);
+
+    /* return 1 if reading direct, 0 if decompressing a gzip stream */
+    return state->direct;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzclose_r(file)
+    gzFile file;
+{
+    int ret;
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return Z_STREAM_ERROR;
+    state = (gz_statep)file;
+
+    /* check that we're reading */
+    if (state->mode != GZ_READ)
+        return Z_STREAM_ERROR;
+
+    /* free memory and close file */
+    if (state->size) {
+        inflateEnd(&(state->strm));
+        free(state->out);
+        free(state->in);
+    }
+    gz_error(state, Z_OK, NULL);
+    free(state->path);
+    ret = close(state->fd);
+    free(state);
+    return ret ? Z_ERRNO : Z_OK;
+}
diff --git a/third_party/zlib/gzwrite.c b/third_party/zlib/gzwrite.c
new file mode 100644
index 0000000..e8defc6
--- /dev/null
+++ b/third_party/zlib/gzwrite.c
@@ -0,0 +1,531 @@
+/* gzwrite.c -- zlib functions for writing gzip files
+ * Copyright (C) 2004, 2005, 2010 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "gzguts.h"
+
+/* Local functions */
+local int gz_init OF((gz_statep));
+local int gz_comp OF((gz_statep, int));
+local int gz_zero OF((gz_statep, z_off64_t));
+
+/* Initialize state for writing a gzip file.  Mark initialization by setting
+   state->size to non-zero.  Return -1 on failure or 0 on success. */
+local int gz_init(state)
+    gz_statep state;
+{
+    int ret;
+    z_streamp strm = &(state->strm);
+
+    /* allocate input and output buffers */
+    state->in = malloc(state->want);
+    state->out = malloc(state->want);
+    if (state->in == NULL || state->out == NULL) {
+        if (state->out != NULL)
+            free(state->out);
+        if (state->in != NULL)
+            free(state->in);
+        gz_error(state, Z_MEM_ERROR, "out of memory");
+        return -1;
+    }
+
+    /* allocate deflate memory, set up for gzip compression */
+    strm->zalloc = Z_NULL;
+    strm->zfree = Z_NULL;
+    strm->opaque = Z_NULL;
+    ret = deflateInit2(strm, state->level, Z_DEFLATED,
+                       15 + 16, 8, state->strategy);
+    if (ret != Z_OK) {
+        free(state->in);
+        gz_error(state, Z_MEM_ERROR, "out of memory");
+        return -1;
+    }
+
+    /* mark state as initialized */
+    state->size = state->want;
+
+    /* initialize write buffer */
+    strm->avail_out = state->size;
+    strm->next_out = state->out;
+    state->next = strm->next_out;
+    return 0;
+}
+
+/* Compress whatever is at avail_in and next_in and write to the output file.
+   Return -1 if there is an error writing to the output file, otherwise 0.
+   flush is assumed to be a valid deflate() flush value.  If flush is Z_FINISH,
+   then the deflate() state is reset to start a new gzip stream. */
+local int gz_comp(state, flush)
+    gz_statep state;
+    int flush;
+{
+    int ret, got;
+    unsigned have;
+    z_streamp strm = &(state->strm);
+
+    /* allocate memory if this is the first time through */
+    if (state->size == 0 && gz_init(state) == -1)
+        return -1;
+
+    /* run deflate() on provided input until it produces no more output */
+    ret = Z_OK;
+    do {
+        /* write out current buffer contents if full, or if flushing, but if
+           doing Z_FINISH then don't write until we get to Z_STREAM_END */
+        if (strm->avail_out == 0 || (flush != Z_NO_FLUSH &&
+            (flush != Z_FINISH || ret == Z_STREAM_END))) {
+            have = (unsigned)(strm->next_out - state->next);
+            if (have && ((got = write(state->fd, state->next, have)) < 0 ||
+                         (unsigned)got != have)) {
+                gz_error(state, Z_ERRNO, zstrerror());
+                return -1;
+            }
+            if (strm->avail_out == 0) {
+                strm->avail_out = state->size;
+                strm->next_out = state->out;
+            }
+            state->next = strm->next_out;
+        }
+
+        /* compress */
+        have = strm->avail_out;
+        ret = deflate(strm, flush);
+        if (ret == Z_STREAM_ERROR) {
+            gz_error(state, Z_STREAM_ERROR,
+                      "internal error: deflate stream corrupt");
+            return -1;
+        }
+        have -= strm->avail_out;
+    } while (have);
+
+    /* if that completed a deflate stream, allow another to start */
+    if (flush == Z_FINISH)
+        deflateReset(strm);
+
+    /* all done, no errors */
+    return 0;
+}
+
+/* Compress len zeros to output.  Return -1 on error, 0 on success. */
+local int gz_zero(state, len)
+    gz_statep state;
+    z_off64_t len;
+{
+    int first;
+    unsigned n;
+    z_streamp strm = &(state->strm);
+
+    /* consume whatever's left in the input buffer */
+    if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
+        return -1;
+
+    /* compress len zeros (len guaranteed > 0) */
+    first = 1;
+    while (len) {
+        n = GT_OFF(state->size) || (z_off64_t)state->size > len ?
+            (unsigned)len : state->size;
+        if (first) {
+            memset(state->in, 0, n);
+            first = 0;
+        }
+        strm->avail_in = n;
+        strm->next_in = state->in;
+        state->pos += n;
+        if (gz_comp(state, Z_NO_FLUSH) == -1)
+            return -1;
+        len -= n;
+    }
+    return 0;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzwrite(file, buf, len)
+    gzFile file;
+    voidpc buf;
+    unsigned len;
+{
+    unsigned put = len;
+    unsigned n;
+    gz_statep state;
+    z_streamp strm;
+
+    /* get internal structure */
+    if (file == NULL)
+        return 0;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return 0;
+
+    /* since an int is returned, make sure len fits in one, otherwise return
+       with an error (this avoids the flaw in the interface) */
+    if ((int)len < 0) {
+        gz_error(state, Z_BUF_ERROR, "requested length does not fit in int");
+        return 0;
+    }
+
+    /* if len is zero, avoid unnecessary operations */
+    if (len == 0)
+        return 0;
+
+    /* allocate memory if this is the first time through */
+    if (state->size == 0 && gz_init(state) == -1)
+        return 0;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return 0;
+    }
+
+    /* for small len, copy to input buffer, otherwise compress directly */
+    if (len < state->size) {
+        /* copy to input buffer, compress when full */
+        do {
+            if (strm->avail_in == 0)
+                strm->next_in = state->in;
+            n = state->size - strm->avail_in;
+            if (n > len)
+                n = len;
+            memcpy(strm->next_in + strm->avail_in, buf, n);
+            strm->avail_in += n;
+            state->pos += n;
+            buf = (char *)buf + n;
+            len -= n;
+            if (len && gz_comp(state, Z_NO_FLUSH) == -1)
+                return 0;
+        } while (len);
+    }
+    else {
+        /* consume whatever's left in the input buffer */
+        if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
+            return 0;
+
+        /* directly compress user buffer to file */
+        strm->avail_in = len;
+        strm->next_in = (voidp)buf;
+        state->pos += len;
+        if (gz_comp(state, Z_NO_FLUSH) == -1)
+            return 0;
+    }
+
+    /* input was all buffered or compressed (put will fit in int) */
+    return (int)put;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzputc(file, c)
+    gzFile file;
+    int c;
+{
+    unsigned char buf[1];
+    gz_statep state;
+    z_streamp strm;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return -1;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return -1;
+    }
+
+    /* try writing to input buffer for speed (state->size == 0 if buffer not
+       initialized) */
+    if (strm->avail_in < state->size) {
+        if (strm->avail_in == 0)
+            strm->next_in = state->in;
+        strm->next_in[strm->avail_in++] = c;
+        state->pos++;
+        return c;
+    }
+
+    /* no room in buffer or not initialized, use gz_write() */
+    buf[0] = c;
+    if (gzwrite(file, buf, 1) != 1)
+        return -1;
+    return c;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzputs(file, str)
+    gzFile file;
+    const char *str;
+{
+    int ret;
+    unsigned len;
+
+    /* write string */
+    len = (unsigned)strlen(str);
+    ret = gzwrite(file, str, len);
+    return ret == 0 && len != 0 ? -1 : ret;
+}
+
+#ifdef STDC
+#include <stdarg.h>
+
+/* -- see zlib.h -- */
+int ZEXPORTVA gzprintf (gzFile file, const char *format, ...)
+{
+    int size, len;
+    gz_statep state;
+    z_streamp strm;
+    va_list va;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return 0;
+
+    /* make sure we have some buffer space */
+    if (state->size == 0 && gz_init(state) == -1)
+        return 0;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return 0;
+    }
+
+    /* consume whatever's left in the input buffer */
+    if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
+        return 0;
+
+    /* do the printf() into the input buffer, put length in len */
+    size = (int)(state->size);
+    state->in[size - 1] = 0;
+    va_start(va, format);
+#ifdef NO_vsnprintf
+#  ifdef HAS_vsprintf_void
+    (void)vsprintf(state->in, format, va);
+    va_end(va);
+    for (len = 0; len < size; len++)
+        if (state->in[len] == 0) break;
+#  else
+    len = vsprintf(state->in, format, va);
+    va_end(va);
+#  endif
+#else
+#  ifdef HAS_vsnprintf_void
+    (void)vsnprintf(state->in, size, format, va);
+    va_end(va);
+    len = strlen(state->in);
+#  else
+    len = vsnprintf((char *)(state->in), size, format, va);
+    va_end(va);
+#  endif
+#endif
+
+    /* check that printf() results fit in buffer */
+    if (len <= 0 || len >= (int)size || state->in[size - 1] != 0)
+        return 0;
+
+    /* update buffer and position, defer compression until needed */
+    strm->avail_in = (unsigned)len;
+    strm->next_in = state->in;
+    state->pos += len;
+    return len;
+}
+
+#else /* !STDC */
+
+/* -- see zlib.h -- */
+int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
+                       a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
+    gzFile file;
+    const char *format;
+    int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
+        a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
+{
+    int size, len;
+    gz_statep state;
+    z_streamp strm;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return 0;
+
+    /* make sure we have some buffer space */
+    if (state->size == 0 && gz_init(state) == -1)
+        return 0;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return 0;
+    }
+
+    /* consume whatever's left in the input buffer */
+    if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
+        return 0;
+
+    /* do the printf() into the input buffer, put length in len */
+    size = (int)(state->size);
+    state->in[size - 1] = 0;
+#ifdef NO_snprintf
+#  ifdef HAS_sprintf_void
+    sprintf(state->in, format, a1, a2, a3, a4, a5, a6, a7, a8,
+            a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
+    for (len = 0; len < size; len++)
+        if (state->in[len] == 0) break;
+#  else
+    len = sprintf(state->in, format, a1, a2, a3, a4, a5, a6, a7, a8,
+                a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
+#  endif
+#else
+#  ifdef HAS_snprintf_void
+    snprintf(state->in, size, format, a1, a2, a3, a4, a5, a6, a7, a8,
+             a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
+    len = strlen(state->in);
+#  else
+    len = snprintf(state->in, size, format, a1, a2, a3, a4, a5, a6, a7, a8,
+                 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
+#  endif
+#endif
+
+    /* check that printf() results fit in buffer */
+    if (len <= 0 || len >= (int)size || state->in[size - 1] != 0)
+        return 0;
+
+    /* update buffer and position, defer compression until needed */
+    strm->avail_in = (unsigned)len;
+    strm->next_in = state->in;
+    state->pos += len;
+    return len;
+}
+
+#endif
+
+/* -- see zlib.h -- */
+int ZEXPORT gzflush(file, flush)
+    gzFile file;
+    int flush;
+{
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return Z_STREAM_ERROR;
+
+    /* check flush parameter */
+    if (flush < 0 || flush > Z_FINISH)
+        return Z_STREAM_ERROR;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return -1;
+    }
+
+    /* compress remaining data with requested flush */
+    gz_comp(state, flush);
+    return state->err;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzsetparams(file, level, strategy)
+    gzFile file;
+    int level;
+    int strategy;
+{
+    gz_statep state;
+    z_streamp strm;
+
+    /* get internal structure */
+    if (file == NULL)
+        return Z_STREAM_ERROR;
+    state = (gz_statep)file;
+    strm = &(state->strm);
+
+    /* check that we're writing and that there's no error */
+    if (state->mode != GZ_WRITE || state->err != Z_OK)
+        return Z_STREAM_ERROR;
+
+    /* if no change is requested, then do nothing */
+    if (level == state->level && strategy == state->strategy)
+        return Z_OK;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        if (gz_zero(state, state->skip) == -1)
+            return -1;
+    }
+
+    /* change compression parameters for subsequent input */
+    if (state->size) {
+        /* flush previous input with previous parameters before changing */
+        if (strm->avail_in && gz_comp(state, Z_PARTIAL_FLUSH) == -1)
+            return state->err;
+        deflateParams(strm, level, strategy);
+    }
+    state->level = level;
+    state->strategy = strategy;
+    return Z_OK;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzclose_w(file)
+    gzFile file;
+{
+    int ret = 0;
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return Z_STREAM_ERROR;
+    state = (gz_statep)file;
+
+    /* check that we're writing */
+    if (state->mode != GZ_WRITE)
+        return Z_STREAM_ERROR;
+
+    /* check for seek request */
+    if (state->seek) {
+        state->seek = 0;
+        ret += gz_zero(state, state->skip);
+    }
+
+    /* flush, free memory, and close file */
+    ret += gz_comp(state, Z_FINISH);
+    (void)deflateEnd(&(state->strm));
+    free(state->out);
+    free(state->in);
+    gz_error(state, Z_OK, NULL);
+    free(state->path);
+    ret += close(state->fd);
+    free(state);
+    return ret ? Z_ERRNO : Z_OK;
+}
diff --git a/third_party/zlib/zconf.h b/third_party/zlib/zconf.h
index b88ec7d..73662d8 100644
--- a/third_party/zlib/zconf.h
+++ b/third_party/zlib/zconf.h
@@ -359,7 +359,7 @@ typedef uLong FAR uLongf;
    typedef Byte       *voidp;
 #endif
 
-#ifdef HAVE_UNISTD_H    /* may be set to #if 1 by ./configure */
+#if !defined(_WIN32)
 #  define Z_HAVE_UNISTD_H
 #endif
 
diff --git a/third_party/zlib/zlib.gyp b/third_party/zlib/zlib.gyp
index 8a651f6..a17c09c 100644
--- a/third_party/zlib/zlib.gyp
+++ b/third_party/zlib/zlib.gyp
@@ -29,7 +29,11 @@
             'crc32.h',
             'deflate.c',
             'deflate.h',
-            'gzio.c',
+            'gzclose.c',
+            'gzguts.h',
+            'gzlib.c',
+            'gzread.c',
+            'gzwrite.c',
             'infback.c',
             'inffast.c',
             'inffast.h',