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platform_build/tools/applypatch/imgdiff.c
Doug Zongker 6b2bb3d96d better patching for zip files 
Adds a zip mode ("-z") to imgdiff to construct efficient patches for
zip files (including jars and apks).  We identify the regions within
the zip file containing deflated data, and when a corresponding file
can be found in the source zip, a patch is generated for the
uncompressed version of the data.

The GZIP chunk type is replaced with a DEFLATE chunk type that handles
a raw deflated data stream.  This new DEFLATE chunk can be used for
both gzipped pieces (as found within boot and recovery images) and zip
files (apks, etc.)  The gzip header and footer are handled by NORMAL
chunks on either side of the main DEFLATE chunks.  (Typically these
tiny NORMAL chunks will get merged with adjacent chunks, so the number
of output chunks is unaffected.)

Add a test script that tests the generate-apply cycle on all the zips
and images within a pair of full OTA packages.
2009-07-20 14:45:29 -07:00

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/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This program constructs binary patches for images -- such as boot.img
* and recovery.img -- that consist primarily of large chunks of gzipped
* data interspersed with uncompressed data. Doing a naive bsdiff of
* these files is not useful because small changes in the data lead to
* large changes in the compressed bitstream; bsdiff patches of gzipped
* data are typically as large as the data itself.
*
* To patch these usefully, we break the source and target images up into
* chunks of two types: "normal" and "gzip". Normal chunks are simply
* patched using a plain bsdiff. Gzip chunks are first expanded, then a
* bsdiff is applied to the uncompressed data, then the patched data is
* gzipped using the same encoder parameters. Patched chunks are
* concatenated together to create the output file; the output image
* should be *exactly* the same series of bytes as the target image used
* originally to generate the patch.
*
* To work well with this tool, the gzipped sections of the target
* image must have been generated using the same deflate encoder that
* is available in applypatch, namely, the one in the zlib library.
* In practice this means that images should be compressed using the
* "minigzip" tool included in the zlib distribution, not the GNU gzip
* program.
*
* An "imgdiff" patch consists of a header describing the chunk structure
* of the file and any encoding parameters needed for the gzipped
* chunks, followed by N bsdiff patches, one per chunk.
*
* For a diff to be generated, the source and target images must have the
* same "chunk" structure: that is, the same number of gzipped and normal
* chunks in the same order. Android boot and recovery images currently
* consist of five chunks: a small normal header, a gzipped kernel, a
* small normal section, a gzipped ramdisk, and finally a small normal
* footer.
*
* Caveats: we locate gzipped sections within the source and target
* images by searching for the byte sequence 1f8b0800: 1f8b is the gzip
* magic number; 08 specifies the "deflate" encoding [the only encoding
* supported by the gzip standard]; and 00 is the flags byte. We do not
* currently support any extra header fields (which would be indicated by
* a nonzero flags byte). We also don't handle the case when that byte
* sequence appears spuriously in the file. (Note that it would have to
* occur spuriously within a normal chunk to be a problem.)
*
*
* The imgdiff patch header looks like this:
*
* "IMGDIFF1" (8) [magic number and version]
* chunk count (4)
* for each chunk:
* chunk type (4) [CHUNK_{NORMAL, GZIP, DEFLATE, RAW}]
* if chunk type == CHUNK_NORMAL:
* source start (8)
* source len (8)
* bsdiff patch offset (8) [from start of patch file]
* if chunk type == CHUNK_GZIP: (version 1 only)
* source start (8)
* source len (8)
* bsdiff patch offset (8) [from start of patch file]
* source expanded len (8) [size of uncompressed source]
* target expected len (8) [size of uncompressed target]
* gzip level (4)
* method (4)
* windowBits (4)
* memLevel (4)
* strategy (4)
* gzip header len (4)
* gzip header (gzip header len)
* gzip footer (8)
* if chunk type == CHUNK_DEFLATE: (version 2 only)
* source start (8)
* source len (8)
* bsdiff patch offset (8) [from start of patch file]
* source expanded len (8) [size of uncompressed source]
* target expected len (8) [size of uncompressed target]
* gzip level (4)
* method (4)
* windowBits (4)
* memLevel (4)
* strategy (4)
* if chunk type == RAW: (version 2 only)
* target len (4)
* data (target len)
*
* All integers are little-endian. "source start" and "source len"
* specify the section of the input image that comprises this chunk,
* including the gzip header and footer for gzip chunks. "source
* expanded len" is the size of the uncompressed source data. "target
* expected len" is the size of the uncompressed data after applying
* the bsdiff patch. The next five parameters specify the zlib
* parameters to be used when compressing the patched data, and the
* next three specify the header and footer to be wrapped around the
* compressed data to create the output chunk (so that header contents
* like the timestamp are recreated exactly).
*
* After the header there are 'chunk count' bsdiff patches; the offset
* of each from the beginning of the file is specified in the header.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include "zlib.h"
#include "imgdiff.h"
#include "utils.h"
typedef struct {
int type; // CHUNK_NORMAL, CHUNK_DEFLATE
size_t start; // offset of chunk in original image file
size_t len;
unsigned char* data; // data to be patched (uncompressed, for deflate chunks)
size_t source_start;
size_t source_len;
// --- for CHUNK_DEFLATE chunks only: ---
// original (compressed) deflate data
size_t deflate_len;
unsigned char* deflate_data;
char* filename; // used for zip entries
// deflate encoder parameters
int level, method, windowBits, memLevel, strategy;
size_t source_uncompressed_len;
} ImageChunk;
typedef struct {
int data_offset;
int deflate_len;
int uncomp_len;
char* filename;
} ZipFileEntry;
static int fileentry_compare(const void* a, const void* b) {
int ao = ((ZipFileEntry*)a)->data_offset;
int bo = ((ZipFileEntry*)b)->data_offset;
if (ao < bo) {
return -1;
} else if (ao > bo) {
return 1;
} else {
return 0;
}
}
unsigned char* ReadZip(const char* filename,
int* num_chunks, ImageChunk** chunks,
int include_pseudo_chunk) {
struct stat st;
if (stat(filename, &st) != 0) {
fprintf(stderr, "failed to stat \"%s\": %s\n", filename, strerror(errno));
return NULL;
}
unsigned char* img = malloc(st.st_size);
FILE* f = fopen(filename, "rb");
if (fread(img, 1, st.st_size, f) != st.st_size) {
fprintf(stderr, "failed to read \"%s\" %s\n", filename, strerror(errno));
fclose(f);
return NULL;
}
fclose(f);
// look for the end-of-central-directory record.
int i;
for (i = st.st_size-20; i >= 0 && i > st.st_size - 65600; --i) {
if (img[i] == 0x50 && img[i+1] == 0x4b &&
img[i+2] == 0x05 && img[i+3] == 0x06) {
break;
}
}
// double-check: this archive consists of a single "disk"
if (!(img[i+4] == 0 && img[i+5] == 0 && img[i+6] == 0 && img[i+7] == 0)) {
fprintf(stderr, "can't process multi-disk archive\n");
return NULL;
}
int cdcount = Read2(img+i+8);
int cdoffset = Read4(img+i+16);
ZipFileEntry* temp_entries = malloc(cdcount * sizeof(ZipFileEntry));
int entrycount = 0;
unsigned char* cd = img+cdoffset;
for (i = 0; i < cdcount; ++i) {
if (!(cd[0] == 0x50 && cd[1] == 0x4b && cd[2] == 0x01 && cd[3] == 0x02)) {
fprintf(stderr, "bad central directory entry %d\n", i);
return NULL;
}
int clen = Read4(cd+20); // compressed len
int ulen = Read4(cd+24); // uncompressed len
int nlen = Read2(cd+28); // filename len
int xlen = Read2(cd+30); // extra field len
int mlen = Read2(cd+32); // file comment len
int hoffset = Read4(cd+42); // local header offset
char* filename = malloc(nlen+1);
memcpy(filename, cd+46, nlen);
filename[nlen] = '\0';
int method = Read2(cd+10);
cd += 46 + nlen + xlen + mlen;
if (method != 8) { // 8 == deflate
free(filename);
continue;
}
unsigned char* lh = img + hoffset;
if (!(lh[0] == 0x50 && lh[1] == 0x4b && lh[2] == 0x03 && lh[3] == 0x04)) {
fprintf(stderr, "bad local file header entry %d\n", i);
return NULL;
}
if (Read2(lh+26) != nlen || memcmp(lh+30, filename, nlen) != 0) {
fprintf(stderr, "central dir filename doesn't match local header\n");
return NULL;
}
xlen = Read2(lh+28); // extra field len; might be different from CD entry?
temp_entries[entrycount].data_offset = hoffset+30+nlen+xlen;
temp_entries[entrycount].deflate_len = clen;
temp_entries[entrycount].uncomp_len = ulen;
temp_entries[entrycount].filename = filename;
++entrycount;
}
qsort(temp_entries, entrycount, sizeof(ZipFileEntry), fileentry_compare);
#if 0
printf("found %d deflated entries\n", entrycount);
for (i = 0; i < entrycount; ++i) {
printf("off %10d len %10d unlen %10d %p %s\n",
temp_entries[i].data_offset,
temp_entries[i].deflate_len,
temp_entries[i].uncomp_len,
temp_entries[i].filename,
temp_entries[i].filename);
}
#endif
*num_chunks = 0;
*chunks = malloc((entrycount*2+2) * sizeof(ImageChunk));
ImageChunk* curr = *chunks;
if (include_pseudo_chunk) {
curr->type = CHUNK_NORMAL;
curr->start = 0;
curr->len = st.st_size;
curr->data = img;
curr->filename = NULL;
++curr;
++*num_chunks;
}
int pos = 0;
int nextentry = 0;
while (pos < st.st_size) {
if (nextentry < entrycount && pos == temp_entries[nextentry].data_offset) {
curr->type = CHUNK_DEFLATE;
curr->start = pos;
curr->deflate_len = temp_entries[nextentry].deflate_len;
curr->deflate_data = img + pos;
curr->filename = temp_entries[nextentry].filename;
curr->len = temp_entries[nextentry].uncomp_len;
curr->data = malloc(curr->len);
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = curr->deflate_len;
strm.next_in = curr->deflate_data;
// -15 means we are decoding a 'raw' deflate stream; zlib will
// not expect zlib headers.
int ret = inflateInit2(&strm, -15);
strm.avail_out = curr->len;
strm.next_out = curr->data;
ret = inflate(&strm, Z_NO_FLUSH);
if (ret != Z_STREAM_END) {
fprintf(stderr, "failed to inflate \"%s\"; %d\n", curr->filename, ret);
return NULL;
}
inflateEnd(&strm);
pos += curr->deflate_len;
++nextentry;
++*num_chunks;
++curr;
continue;
}
// use a normal chunk to take all the data up to the start of the
// next deflate section.
curr->type = CHUNK_NORMAL;
curr->start = pos;
if (nextentry < entrycount) {
curr->len = temp_entries[nextentry].data_offset - pos;
} else {
curr->len = st.st_size - pos;
}
curr->data = img + pos;
curr->filename = NULL;
pos += curr->len;
++*num_chunks;
++curr;
}
free(temp_entries);
return img;
}
/*
* Read the given file and break it up into chunks, putting the number
* of chunks and their info in *num_chunks and **chunks,
* respectively. Returns a malloc'd block of memory containing the
* contents of the file; various pointers in the output chunk array
* will point into this block of memory. The caller should free the
* return value when done with all the chunks. Returns NULL on
* failure.
*/
unsigned char* ReadImage(const char* filename,
int* num_chunks, ImageChunk** chunks) {
struct stat st;
if (stat(filename, &st) != 0) {
fprintf(stderr, "failed to stat \"%s\": %s\n", filename, strerror(errno));
return NULL;
}
unsigned char* img = malloc(st.st_size + 4);
FILE* f = fopen(filename, "rb");
if (fread(img, 1, st.st_size, f) != st.st_size) {
fprintf(stderr, "failed to read \"%s\" %s\n", filename, strerror(errno));
fclose(f);
return NULL;
}
fclose(f);
// append 4 zero bytes to the data so we can always search for the
// four-byte string 1f8b0800 starting at any point in the actual
// file data, without special-casing the end of the data.
memset(img+st.st_size, 0, 4);
size_t pos = 0;
*num_chunks = 0;
*chunks = NULL;
while (pos < st.st_size) {
unsigned char* p = img+pos;
if (st.st_size - pos >= 4 &&
p[0] == 0x1f && p[1] == 0x8b &&
p[2] == 0x08 && // deflate compression
p[3] == 0x00) { // no header flags
// 'pos' is the offset of the start of a gzip chunk.
*num_chunks += 3;
*chunks = realloc(*chunks, *num_chunks * sizeof(ImageChunk));
ImageChunk* curr = *chunks + (*num_chunks-3);
// create a normal chunk for the header.
curr->start = pos;
curr->type = CHUNK_NORMAL;
curr->len = GZIP_HEADER_LEN;
curr->data = p;
pos += curr->len;
p += curr->len;
++curr;
curr->type = CHUNK_DEFLATE;
curr->filename = NULL;
// We must decompress this chunk in order to discover where it
// ends, and so we can put the uncompressed data and its length
// into curr->data and curr->len.
size_t allocated = 32768;
curr->len = 0;
curr->data = malloc(allocated);
curr->start = pos;
curr->deflate_data = p;
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = st.st_size - pos;
strm.next_in = p;
// -15 means we are decoding a 'raw' deflate stream; zlib will
// not expect zlib headers.
int ret = inflateInit2(&strm, -15);
do {
strm.avail_out = allocated - curr->len;
strm.next_out = curr->data + curr->len;
ret = inflate(&strm, Z_NO_FLUSH);
curr->len = allocated - strm.avail_out;
if (strm.avail_out == 0) {
allocated *= 2;
curr->data = realloc(curr->data, allocated);
}
} while (ret != Z_STREAM_END);
curr->deflate_len = st.st_size - strm.avail_in - pos;
inflateEnd(&strm);
pos += curr->deflate_len;
p += curr->deflate_len;
++curr;
// create a normal chunk for the footer
curr->type = CHUNK_NORMAL;
curr->start = pos;
curr->len = GZIP_FOOTER_LEN;
curr->data = img+pos;
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) {
fprintf(stderr, "Error: footer size %d != decompressed size %d\n",
footer_size, curr[-2].len);
free(img);
return NULL;
}
} else {
// Reallocate the list for every chunk; we expect the number of
// chunks to be small (5 for typical boot and recovery images).
++*num_chunks;
*chunks = realloc(*chunks, *num_chunks * sizeof(ImageChunk));
ImageChunk* curr = *chunks + (*num_chunks-1);
curr->start = pos;
// 'pos' is not the offset of the start of a gzip chunk, so scan
// forward until we find a gzip header.
curr->type = CHUNK_NORMAL;
curr->data = p;
for (curr->len = 0; curr->len < (st.st_size - pos); ++curr->len) {
if (p[curr->len] == 0x1f &&
p[curr->len+1] == 0x8b &&
p[curr->len+2] == 0x08 &&
p[curr->len+3] == 0x00) {
break;
}
}
pos += curr->len;
}
}
return img;
}
#define BUFFER_SIZE 32768
/*
* Takes the uncompressed data stored in the chunk, compresses it
* using the zlib parameters stored in the chunk, and checks that it
* matches exactly the compressed data we started with (also stored in
* the chunk). Return 0 on success.
*/
int TryReconstruction(ImageChunk* chunk, unsigned char* out) {
size_t p = 0;
#if 0
fprintf(stderr, "trying %d %d %d %d %d\n",
chunk->level, chunk->method, chunk->windowBits,
chunk->memLevel, chunk->strategy);
#endif
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = chunk->len;
strm.next_in = chunk->data;
int ret;
ret = deflateInit2(&strm, chunk->level, chunk->method, chunk->windowBits,
chunk->memLevel, chunk->strategy);
do {
strm.avail_out = BUFFER_SIZE;
strm.next_out = out;
ret = deflate(&strm, Z_FINISH);
size_t have = BUFFER_SIZE - strm.avail_out;
if (memcmp(out, chunk->deflate_data+p, have) != 0) {
// mismatch; data isn't the same.
deflateEnd(&strm);
return -1;
}
p += have;
} while (ret != Z_STREAM_END);
deflateEnd(&strm);
if (p != chunk->deflate_len) {
// mismatch; ran out of data before we should have.
return -1;
}
return 0;
}
/*
* Verify that we can reproduce exactly the same compressed data that
* we started with. Sets the level, method, windowBits, memLevel, and
* strategy fields in the chunk to the encoding parameters needed to
* produce the right output. Returns 0 on success.
*/
int ReconstructDeflateChunk(ImageChunk* chunk) {
if (chunk->type != CHUNK_DEFLATE) {
fprintf(stderr, "attempt to reconstruct non-deflate chunk\n");
return -1;
}
size_t p = 0;
unsigned char* out = malloc(BUFFER_SIZE);
// We only check two combinations of encoder parameters: level 6
// (the default) and level 9 (the maximum).
for (chunk->level = 6; chunk->level <= 9; chunk->level += 3) {
chunk->windowBits = -15; // 32kb window; negative to indicate a raw stream.
chunk->memLevel = 8; // the default value.
chunk->method = Z_DEFLATED;
chunk->strategy = Z_DEFAULT_STRATEGY;
if (TryReconstruction(chunk, out) == 0) {
free(out);
return 0;
}
}
free(out);
return -1;
}
/*
* Given source and target chunks, compute a bsdiff patch between them
* by running bsdiff in a subprocess. Return the patch data, placing
* its length in *size. Return NULL on failure. We expect the bsdiff
* program to be in the path.
*/
unsigned char* MakePatch(ImageChunk* src, ImageChunk* tgt, size_t* size) {
if (tgt->type == CHUNK_NORMAL) {
if (tgt->len <= 160) {
tgt->type = CHUNK_RAW;
*size = tgt->len;
return tgt->data;
}
}
char stemp[] = "/tmp/imgdiff-src-XXXXXX";
char ttemp[] = "/tmp/imgdiff-tgt-XXXXXX";
char ptemp[] = "/tmp/imgdiff-patch-XXXXXX";
mkstemp(stemp);
mkstemp(ttemp);
mkstemp(ptemp);
FILE* f = fopen(stemp, "wb");
if (f == NULL) {
fprintf(stderr, "failed to open src chunk %s: %s\n",
stemp, strerror(errno));
return NULL;
}
if (fwrite(src->data, 1, src->len, f) != src->len) {
fprintf(stderr, "failed to write src chunk to %s: %s\n",
stemp, strerror(errno));
return NULL;
}
fclose(f);
f = fopen(ttemp, "wb");
if (f == NULL) {
fprintf(stderr, "failed to open tgt chunk %s: %s\n",
ttemp, strerror(errno));
return NULL;
}
if (fwrite(tgt->data, 1, tgt->len, f) != tgt->len) {
fprintf(stderr, "failed to write tgt chunk to %s: %s\n",
ttemp, strerror(errno));
return NULL;
}
fclose(f);
char cmd[200];
sprintf(cmd, "bsdiff %s %s %s", stemp, ttemp, ptemp);
if (system(cmd) != 0) {
fprintf(stderr, "failed to run bsdiff: %s\n", strerror(errno));
return NULL;
}
struct stat st;
if (stat(ptemp, &st) != 0) {
fprintf(stderr, "failed to stat patch file %s: %s\n",
ptemp, strerror(errno));
return NULL;
}
unsigned char* data = malloc(st.st_size);
if (tgt->type == CHUNK_NORMAL && tgt->len <= st.st_size) {
unlink(stemp);
unlink(ttemp);
unlink(ptemp);
tgt->type = CHUNK_RAW;
*size = tgt->len;
return tgt->data;
}
*size = st.st_size;
f = fopen(ptemp, "rb");
if (f == NULL) {
fprintf(stderr, "failed to open patch %s: %s\n", ptemp, strerror(errno));
return NULL;
}
if (fread(data, 1, st.st_size, f) != st.st_size) {
fprintf(stderr, "failed to read patch %s: %s\n", ptemp, strerror(errno));
return NULL;
}
fclose(f);
unlink(stemp);
unlink(ttemp);
unlink(ptemp);
tgt->source_start = src->start;
switch (tgt->type) {
case CHUNK_NORMAL:
tgt->source_len = src->len;
break;
case CHUNK_DEFLATE:
tgt->source_len = src->deflate_len;
tgt->source_uncompressed_len = src->len;
break;
}
return data;
}
/*
* Cause a gzip chunk to be treated as a normal chunk (ie, as a blob
* of uninterpreted data). The resulting patch will likely be about
* as big as the target file, but it lets us handle the case of images
* where some gzip chunks are reconstructible but others aren't (by
* treating the ones that aren't as normal chunks).
*/
void ChangeDeflateChunkToNormal(ImageChunk* ch) {
if (ch->type != CHUNK_DEFLATE) return;
ch->type = CHUNK_NORMAL;
free(ch->data);
ch->data = ch->deflate_data;
ch->len = ch->deflate_len;
}
/*
* Return true if the data in the chunk is identical (including the
* compressed representation, for gzip chunks).
*/
int AreChunksEqual(ImageChunk* a, ImageChunk* b) {
if (a->type != b->type) return 0;
switch (a->type) {
case CHUNK_NORMAL:
return a->len == b->len && memcmp(a->data, b->data, a->len) == 0;
case CHUNK_DEFLATE:
return a->deflate_len == b->deflate_len &&
memcmp(a->deflate_data, b->deflate_data, a->deflate_len) == 0;
default:
fprintf(stderr, "unknown chunk type %d\n", a->type);
return 0;
}
}
/*
* Look for runs of adjacent normal chunks and compress them down into
* a single chunk. (Such runs can be produced when deflate chunks are
* changed to normal chunks.)
*/
void MergeAdjacentNormalChunks(ImageChunk* chunks, int* num_chunks) {
int out = 0;
int in_start = 0, in_end;
while (in_start < *num_chunks) {
if (chunks[in_start].type != CHUNK_NORMAL) {
in_end = in_start+1;
} else {
// in_start is a normal chunk. Look for a run of normal chunks
// that constitute a solid block of data (ie, each chunk begins
// where the previous one ended).
for (in_end = in_start+1;
in_end < *num_chunks && chunks[in_end].type == CHUNK_NORMAL &&
(chunks[in_end].start ==
chunks[in_end-1].start + chunks[in_end-1].len &&
chunks[in_end].data ==
chunks[in_end-1].data + chunks[in_end-1].len);
++in_end);
}
if (in_end == in_start+1) {
#if 0
printf("chunk %d is now %d\n", in_start, out);
#endif
if (out != in_start) {
memcpy(chunks+out, chunks+in_start, sizeof(ImageChunk));
}
} else {
#if 0
printf("collapse normal chunks %d-%d into %d\n", in_start, in_end-1, out);
#endif
// Merge chunks [in_start, in_end-1] into one chunk. Since the
// data member of each chunk is just a pointer into an in-memory
// copy of the file, this can be done without recopying (the
// output chunk has the first chunk's start location and data
// pointer, and length equal to the sum of the input chunk
// lengths).
chunks[out].type = CHUNK_NORMAL;
chunks[out].start = chunks[in_start].start;
chunks[out].data = chunks[in_start].data;
chunks[out].len = chunks[in_end-1].len +
(chunks[in_end-1].start - chunks[in_start].start);
}
++out;
in_start = in_end;
}
*num_chunks = out;
}
ImageChunk* FindChunkByName(const char* name,
ImageChunk* chunks, int num_chunks) {
int i;
for (i = 0; i < num_chunks; ++i) {
if (chunks[i].type == CHUNK_DEFLATE && chunks[i].filename &&
strcmp(name, chunks[i].filename) == 0) {
return chunks+i;
}
}
return NULL;
}
int main(int argc, char** argv) {
if (argc != 4 && argc != 5) {
usage:
fprintf(stderr, "usage: %s [-z] <src-img> <tgt-img> <patch-file>\n",
argv[0]);
return 2;
}
int zip_mode = 0;
if (strcmp(argv[1], "-z") == 0) {
zip_mode = 1;
--argc;
++argv;
}
int num_src_chunks;
ImageChunk* src_chunks;
int num_tgt_chunks;
ImageChunk* tgt_chunks;
int i;
if (zip_mode) {
if (ReadZip(argv[1], &num_src_chunks, &src_chunks, 1) == NULL) {
fprintf(stderr, "failed to break apart source zip file\n");
return 1;
}
if (ReadZip(argv[2], &num_tgt_chunks, &tgt_chunks, 0) == NULL) {
fprintf(stderr, "failed to break apart target zip file\n");
return 1;
}
} else {
if (ReadImage(argv[1], &num_src_chunks, &src_chunks) == NULL) {
fprintf(stderr, "failed to break apart source image\n");
return 1;
}
if (ReadImage(argv[2], &num_tgt_chunks, &tgt_chunks) == NULL) {
fprintf(stderr, "failed to break apart target image\n");
return 1;
}
// Verify that the source and target images have the same chunk
// structure (ie, the same sequence of deflate and normal chunks).
if (num_src_chunks != num_tgt_chunks) {
fprintf(stderr, "source and target don't have same number of chunks!\n");
return 1;
}
for (i = 0; i < num_src_chunks; ++i) {
if (src_chunks[i].type != tgt_chunks[i].type) {
fprintf(stderr, "source and target don't have same chunk "
"structure! (chunk %d)\n", i);
return 1;
}
}
}
for (i = 0; i < num_tgt_chunks; ++i) {
if (tgt_chunks[i].type == CHUNK_DEFLATE) {
// Confirm that given the uncompressed chunk data in the target, we
// can recompress it and get exactly the same bits as are in the
// input target image. If this fails, treat the chunk as a normal
// non-deflated chunk.
if (ReconstructDeflateChunk(tgt_chunks+i) < 0) {
printf("failed to reconstruct target deflate chunk %d [%s]; "
"treating as normal\n", i, tgt_chunks[i].filename);
ChangeDeflateChunkToNormal(tgt_chunks+i);
if (zip_mode) {
ImageChunk* src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
if (src) {
ChangeDeflateChunkToNormal(src);
}
} else {
ChangeDeflateChunkToNormal(src_chunks+i);
}
continue;
}
// If two deflate chunks are identical (eg, the kernel has not
// changed between two builds), treat them as normal chunks.
// This makes applypatch much faster -- it can apply a trivial
// patch to the compressed data, rather than uncompressing and
// recompressing to apply the trivial patch to the uncompressed
// data.
ImageChunk* src;
if (zip_mode) {
src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
} else {
src = src_chunks+i;
}
if (src == NULL || AreChunksEqual(tgt_chunks+i, src)) {
ChangeDeflateChunkToNormal(tgt_chunks+i);
if (src) {
ChangeDeflateChunkToNormal(src);
}
}
}
}
// Merging neighboring normal chunks.
if (zip_mode) {
// For zips, we only need to do this to the target: deflated
// chunks are matched via filename, and normal chunks are patched
// using the entire source file as the source.
MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
} else {
// For images, we need to maintain the parallel structure of the
// chunk lists, so do the merging in both the source and target
// lists.
MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
if (num_src_chunks != num_tgt_chunks) {
// This shouldn't happen.
fprintf(stderr, "merging normal chunks went awry\n");
return 1;
}
}
// Compute bsdiff patches for each chunk's data (the uncompressed
// data, in the case of deflate chunks).
printf("Construct patches for %d chunks...\n", num_tgt_chunks);
unsigned char** patch_data = malloc(num_tgt_chunks * sizeof(unsigned char*));
size_t* patch_size = malloc(num_tgt_chunks * sizeof(size_t));
for (i = 0; i < num_tgt_chunks; ++i) {
if (zip_mode) {
ImageChunk* src;
if (tgt_chunks[i].type == CHUNK_DEFLATE &&
(src = FindChunkByName(tgt_chunks[i].filename, src_chunks,
num_src_chunks))) {
patch_data[i] = MakePatch(src, tgt_chunks+i, patch_size+i);
} else {
patch_data[i] = MakePatch(src_chunks, tgt_chunks+i, patch_size+i);
}
} else {
patch_data[i] = MakePatch(src_chunks+i, tgt_chunks+i, patch_size+i);
}
printf("patch %3d is %d bytes (of %d)\n",
i, patch_size[i], tgt_chunks[i].source_len);
}
// Figure out how big the imgdiff file header is going to be, so
// that we can correctly compute the offset of each bsdiff patch
// within the file.
size_t total_header_size = 12;
for (i = 0; i < num_tgt_chunks; ++i) {
total_header_size += 4;
switch (tgt_chunks[i].type) {
case CHUNK_NORMAL:
total_header_size += 8*3;
break;
case CHUNK_DEFLATE:
total_header_size += 8*5 + 4*5;
break;
case CHUNK_RAW:
total_header_size += 4 + patch_size[i];
break;
}
}
size_t offset = total_header_size;
FILE* f = fopen(argv[3], "wb");
// Write out the headers.
fwrite("IMGDIFF2", 1, 8, f);
Write4(num_tgt_chunks, f);
for (i = 0; i < num_tgt_chunks; ++i) {
Write4(tgt_chunks[i].type, f);
switch (tgt_chunks[i].type) {
case CHUNK_NORMAL:
printf("chunk %3d: normal (%10d, %10d) %10d\n", i,
tgt_chunks[i].start, tgt_chunks[i].len, patch_size[i]);
Write8(tgt_chunks[i].source_start, f);
Write8(tgt_chunks[i].source_len, f);
Write8(offset, f);
offset += patch_size[i];
break;
case CHUNK_DEFLATE:
printf("chunk %3d: deflate (%10d, %10d) %10d %s\n", i,
tgt_chunks[i].start, tgt_chunks[i].deflate_len, patch_size[i],
tgt_chunks[i].filename);
Write8(tgt_chunks[i].source_start, f);
Write8(tgt_chunks[i].source_len, f);
Write8(offset, f);
Write8(tgt_chunks[i].source_uncompressed_len, f);
Write8(tgt_chunks[i].len, f);
Write4(tgt_chunks[i].level, f);
Write4(tgt_chunks[i].method, f);
Write4(tgt_chunks[i].windowBits, f);
Write4(tgt_chunks[i].memLevel, f);
Write4(tgt_chunks[i].strategy, f);
offset += patch_size[i];
break;
case CHUNK_RAW:
printf("chunk %3d: raw (%10d, %10d)\n", i,
tgt_chunks[i].start, tgt_chunks[i].len);
Write4(patch_size[i], f);
fwrite(patch_data[i], 1, patch_size[i], f);
break;
}
}
// Append each chunk's bsdiff patch, in order.
for (i = 0; i < num_tgt_chunks; ++i) {
if (tgt_chunks[i].type != CHUNK_RAW) {
fwrite(patch_data[i], 1, patch_size[i], f);
}
}
fclose(f);
return 0;
}
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