imgdiff: skip spurious gzip headers in image files
dragon kernel is compressed via lz4 for boot speed and bootloader
support reasons and recent prebuilts happen to include the gzip header
sequence which is causing imgdiff to fail.
Detect a spurious gzip header and treat the section as a normal section.
Bug: 26133184
Change-Id: I369d7d576fd7d2c579c0780fc5c669a5b6ea0d3d
diff --git a/applypatch/imgdiff.c b/applypatch/imgdiff.c
index 3bac8be..49a1e39 100644
--- a/applypatch/imgdiff.c
+++ b/applypatch/imgdiff.c
@@ -403,6 +403,7 @@
while (pos < st.st_size) {
unsigned char* p = img+pos;
+ int processed_deflate = 0;
if (st.st_size - pos >= 4 &&
p[0] == 0x1f && p[1] == 0x8b &&
p[2] == 0x08 && // deflate compression
@@ -455,48 +456,65 @@
strm.next_out = curr->data + curr->len;
ret = inflate(&strm, Z_NO_FLUSH);
if (ret < 0) {
- printf("Error: inflate failed [%s] at file offset [%zu]\n"
- "imgdiff only supports gzip kernel compression,"
- " did you try CONFIG_KERNEL_LZO?\n",
- strm.msg, chunk_offset);
- free(img);
- return NULL;
+ if (!processed_deflate) {
+ // This is the first chunk, assume that it's just a spurious
+ // gzip header instead of a real one.
+ break;
+ }
+ printf("Error: inflate failed [%s] at file offset [%zu]\n"
+ "imgdiff only supports gzip kernel compression,"
+ " did you try CONFIG_KERNEL_LZO?\n",
+ strm.msg, chunk_offset);
+ free(img);
+ return NULL;
}
curr->len = allocated - strm.avail_out;
if (strm.avail_out == 0) {
allocated *= 2;
curr->data = realloc(curr->data, allocated);
}
+ processed_deflate = 1;
} while (ret != Z_STREAM_END);
- curr->deflate_len = st.st_size - strm.avail_in - pos;
- inflateEnd(&strm);
- pos += curr->deflate_len;
- p += curr->deflate_len;
- ++curr;
+ if (ret == Z_STREAM_END) {
+ // Properly deflated a gzip'd section.
+ curr->deflate_len = st.st_size - strm.avail_in - pos;
+ inflateEnd(&strm);
+ pos += curr->deflate_len;
+ p += curr->deflate_len;
+ ++curr;
- // create a normal chunk for the footer
+ // create a normal chunk for the footer
- curr->type = CHUNK_NORMAL;
- curr->start = pos;
- curr->len = GZIP_FOOTER_LEN;
- curr->data = img+pos;
- curr->I = NULL;
+ curr->type = CHUNK_NORMAL;
+ curr->start = pos;
+ curr->len = GZIP_FOOTER_LEN;
+ curr->data = img+pos;
+ curr->I = NULL;
- pos += curr->len;
- p += curr->len;
- ++curr;
+ pos += curr->len;
+ p += curr->len;
+ ++curr;
- // The footer (that we just skipped over) contains the size of
- // the uncompressed data. Double-check to make sure that it
- // matches the size of the data we got when we actually did
- // the decompression.
- size_t footer_size = Read4(p-4);
- if (footer_size != curr[-2].len) {
- printf("Error: footer size %d != decompressed size %d\n",
- footer_size, curr[-2].len);
- free(img);
- return NULL;
+ // The footer (that we just skipped over) contains the size of
+ // the uncompressed data. Double-check to make sure that it
+ // matches the size of the data we got when we actually did
+ // the decompression.
+ size_t footer_size = Read4(p-4);
+ if (footer_size != curr[-2].len) {
+ printf("Error: footer size %d != decompressed size %d\n",
+ footer_size, curr[-2].len);
+ free(img);
+ return NULL;
+ }
+ } else {
+ // Didn't deflate a gzip section at all, treat as spurious
+ // gzip header by skipping this chunk and begin search after
+ // previous header without advancing the current chunk.
+ printf("Warning: skipping spurious gzip header at offset %zu\n",
+ pos - GZIP_HEADER_LEN);
+ *num_chunks -= 2;
+ free(curr->data);
}
} else {
// Reallocate the list for every chunk; we expect the number of
