make offsets in firmware update header not point to bad blocks

hboot will apparently fail to install if the first block of the image
(the one pointed to by the offset in the block 0 header) is a bad
block.  (Hopefully it handles subsequent bad blocks.)

This change makes the MTD write code keep track of the bad blocks it
has skipped over, so that the offset in the header can be adjusted to
be the address of the first successfully written block.

Change-Id: I45d58e32a36d0c1dbc0a7f871bd5985b6c8ff524
http://b/2358012 - passion: failure to flash hboot (bad blocks?)

2 files changed, 43 insertions, 4 deletions

diff --git a/mtdutils/mtdutils.c b/mtdutils/mtdutils.c
index 8d32520..18e6a5d 100644
--- a/mtdutils/mtdutils.c
+++ b/mtdutils/mtdutils.c
@@ -47,6 +47,10 @@ struct MtdWriteContext {
     char *buffer;
     size_t stored;
     int fd;
+
+    off_t* bad_block_offsets;
+    int bad_block_alloc;
+    int bad_block_count;
 };
 
 typedef struct {
@@ -366,6 +370,10 @@ MtdWriteContext *mtd_write_partition(const MtdPartition *partition)
     MtdWriteContext *ctx = (MtdWriteContext*) malloc(sizeof(MtdWriteContext));
     if (ctx == NULL) return NULL;
 
+    ctx->bad_block_offsets = NULL;
+    ctx->bad_block_alloc = 0;
+    ctx->bad_block_count = 0;
+
     ctx->buffer = malloc(partition->erase_size);
     if (ctx->buffer == NULL) {
         free(ctx);
@@ -386,8 +394,20 @@ MtdWriteContext *mtd_write_partition(const MtdPartition *partition)
     return ctx;
 }
 
-static int write_block(const MtdPartition *partition, int fd, const char *data)
+static void add_bad_block_offset(MtdWriteContext *ctx, off_t pos) {
+    if (ctx->bad_block_count + 1 > ctx->bad_block_alloc) {
+        ctx->bad_block_alloc = (ctx->bad_block_alloc*2) + 1;
+        ctx->bad_block_offsets = realloc(ctx->bad_block_offsets,
+                                         ctx->bad_block_alloc * sizeof(off_t));
+    }
+    ctx->bad_block_offsets[ctx->bad_block_count++] = pos;
+}
+
+static int write_block(MtdWriteContext *ctx, const char *data)
 {
+    const MtdPartition *partition = ctx->partition;
+    int fd = ctx->fd;
+
     off_t pos = lseek(fd, 0, SEEK_CUR);
     if (pos == (off_t) -1) return 1;
 
@@ -395,6 +415,7 @@ static int write_block(const MtdPartition *partition, int fd, const char *data)
     while (pos + size <= (int) partition->size) {
         loff_t bpos = pos;
         if (ioctl(fd, MEMGETBADBLOCK, &bpos) > 0) {
+            add_bad_block_offset(ctx, pos);
             fprintf(stderr, "mtd: not writing bad block at 0x%08lx\n", pos);
             pos += partition->erase_size;
             continue;  // Don't try to erase known factory-bad blocks.
@@ -436,6 +457,7 @@ static int write_block(const MtdPartition *partition, int fd, const char *data)
         }
 
         // Try to erase it once more as we give up on this block
+        add_bad_block_offset(ctx, pos);
         fprintf(stderr, "mtd: skipping write block at 0x%08lx\n", pos);
         ioctl(fd, MEMERASE, &erase_info);
         pos += partition->erase_size;
@@ -461,13 +483,13 @@ ssize_t mtd_write_data(MtdWriteContext *ctx, const char *data, size_t len)
 
         // If a complete block was accumulated, write it
         if (ctx->stored == ctx->partition->erase_size) {
-            if (write_block(ctx->partition, ctx->fd, ctx->buffer)) return -1;
+            if (write_block(ctx, ctx->buffer)) return -1;
             ctx->stored = 0;
         }
 
         // Write complete blocks directly from the user's buffer
         while (ctx->stored == 0 && len - wrote >= ctx->partition->erase_size) {
-            if (write_block(ctx->partition, ctx->fd, data + wrote)) return -1;
+            if (write_block(ctx, data + wrote)) return -1;
             wrote += ctx->partition->erase_size;
         }
     }
@@ -481,7 +503,7 @@ off_t mtd_erase_blocks(MtdWriteContext *ctx, int blocks)
     if (ctx->stored > 0) {
         size_t zero = ctx->partition->erase_size - ctx->stored;
         memset(ctx->buffer + ctx->stored, 0, zero);
-        if (write_block(ctx->partition, ctx->fd, ctx->buffer)) return -1;
+        if (write_block(ctx, ctx->buffer)) return -1;
         ctx->stored = 0;
     }
 
@@ -522,7 +544,23 @@ int mtd_write_close(MtdWriteContext *ctx)
     // Make sure any pending data gets written
     if (mtd_erase_blocks(ctx, 0) == (off_t) -1) r = -1;
     if (close(ctx->fd)) r = -1;
+    free(ctx->bad_block_offsets);
     free(ctx->buffer);
     free(ctx);
     return r;
 }
+
+/* Return the offset of the first good block at or after pos (which
+ * might be pos itself).
+ */
+off_t mtd_find_write_start(MtdWriteContext *ctx, off_t pos) {
+    int i;
+    for (i = 0; i < ctx->bad_block_count; ++i) {
+        if (ctx->bad_block_offsets[i] == pos) {
+            pos += ctx->partition->erase_size;
+        } else if (ctx->bad_block_offsets[i] > pos) {
+            return pos;
+        }
+    }
+    return pos;
+}
diff --git a/mtdutils/mtdutils.h b/mtdutils/mtdutils.h
index 8d2cb56..528a5bb 100644
--- a/mtdutils/mtdutils.h
+++ b/mtdutils/mtdutils.h
@@ -49,6 +49,7 @@ void mtd_read_close(MtdReadContext *);
 MtdWriteContext *mtd_write_partition(const MtdPartition *);
 ssize_t mtd_write_data(MtdWriteContext *, const char *data, size_t data_len);
 off_t mtd_erase_blocks(MtdWriteContext *, int blocks);  /* 0 ok, -1 for all */
+off_t mtd_find_write_start(MtdWriteContext *ctx, off_t pos);
 int mtd_write_close(MtdWriteContext *);
 
 #endif  // MTDUTILS_H_