/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// See imgdiff.c in this directory for a description of the patch file
// format.
#include <stdio.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include "zlib.h"
#include "mincrypt/sha.h"
#include "applypatch.h"
#include "imgdiff.h"
#include "utils.h"
/*
* Apply the patch given in 'patch_filename' to the source data given
* by (old_data, old_size). Write the patched output to the 'output'
* file, and update the SHA context with the output data as well.
* Return 0 on success.
*/
int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
const Value* patch,
SinkFn sink, void* token, SHA_CTX* ctx) {
ssize_t pos = 12;
char* header = patch->data;
if (patch->size < 12) {
printf("patch too short to contain header\n");
return -1;
}
// IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
// (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
// CHUNK_GZIP.)
if (memcmp(header, "IMGDIFF2", 8) != 0) {
printf("corrupt patch file header (magic number)\n");
return -1;
}
int num_chunks = Read4(header+8);
int i;
for (i = 0; i < num_chunks; ++i) {
// each chunk's header record starts with 4 bytes.
if (pos + 4 > patch->size) {
printf("failed to read chunk %d record\n", i);
return -1;
}
int type = Read4(patch->data + pos);
pos += 4;
if (type == CHUNK_NORMAL) {
char* normal_header = patch->data + pos;
pos += 24;
if (pos > patch->size) {
printf("failed to read chunk %d normal header data\n", i);
return -1;
}
size_t src_start = Read8(normal_header);
size_t src_len = Read8(normal_header+8);
size_t patch_offset = Read8(normal_header+16);
ApplyBSDiffPatch(old_data + src_start, src_len,
patch, patch_offset, sink, token, ctx);
} else if (type == CHUNK_RAW) {
char* raw_header = patch->data + pos;
pos += 4;
if (pos > patch->size) {
printf("failed to read chunk %d raw header data\n", i);
return -1;
}
ssize_t data_len = Read4(raw_header);
if (pos + data_len > patch->size) {
printf("failed to read chunk %d raw data\n", i);
return -1;
}
SHA_update(ctx, patch->data + pos, data_len);
if (sink((unsigned char*)patch->data + pos,
data_len, token) != data_len) {
printf("failed to write chunk %d raw data\n", i);
return -1;
}
pos += data_len;
} else if (type == CHUNK_DEFLATE) {
// deflate chunks have an additional 60 bytes in their chunk header.
char* deflate_header = patch->data + pos;
pos += 60;
if (pos > patch->size) {
printf("failed to read chunk %d deflate header data\n", i);
return -1;
}
size_t src_start = Read8(deflate_header);
size_t src_len = Read8(deflate_header+8);
size_t patch_offset = Read8(deflate_header+16);
size_t expanded_len = Read8(deflate_header+24);
size_t target_len = Read8(deflate_header+32);
int level = Read4(deflate_header+40);
int method = Read4(deflate_header+44);
int windowBits = Read4(deflate_header+48);
int memLevel = Read4(deflate_header+52);
int strategy = Read4(deflate_header+56);
// Decompress the source data; the chunk header tells us exactly
// how big we expect it to be when decompressed.
unsigned char* expanded_source = malloc(expanded_len);
if (expanded_source == NULL) {
printf("failed to allocate %d bytes for expanded_source\n",
expanded_len);
return -1;
}
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = src_len;
strm.next_in = (unsigned char*)(old_data + src_start);
strm.avail_out = expanded_len;
strm.next_out = expanded_source;
int ret;
ret = inflateInit2(&strm, -15);
if (ret != Z_OK) {
printf("failed to init source inflation: %d\n", ret);
return -1;
}
// Because we've provided enough room to accommodate the output
// data, we expect one call to inflate() to suffice.
ret = inflate(&strm, Z_SYNC_FLUSH);
if (ret != Z_STREAM_END) {
printf("source inflation returned %d\n", ret);
return -1;
}
// We should have filled the output buffer exactly.
if (strm.avail_out != 0) {
printf("source inflation short by %d bytes\n", strm.avail_out);
return -1;
}
inflateEnd(&strm);
// Next, apply the bsdiff patch (in memory) to the uncompressed
// data.
unsigned char* uncompressed_target_data;
ssize_t uncompressed_target_size;
if (ApplyBSDiffPatchMem(expanded_source, expanded_len,
patch, patch_offset,
&uncompressed_target_data,
&uncompressed_target_size) != 0) {
return -1;
}
// Now compress the target data and append it to the output.
// we're done with the expanded_source data buffer, so we'll
// reuse that memory to receive the output of deflate.
unsigned char* temp_data = expanded_source;
ssize_t temp_size = expanded_len;
if (temp_size < 32768) {
// ... unless the buffer is too small, in which case we'll
// allocate a fresh one.
free(temp_data);
temp_data = malloc(32768);
temp_size = 32768;
}
// now the deflate stream
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = uncompressed_target_size;
strm.next_in = uncompressed_target_data;
ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
do {
strm.avail_out = temp_size;
strm.next_out = temp_data;
ret = deflate(&strm, Z_FINISH);
ssize_t have = temp_size - strm.avail_out;
if (sink(temp_data, have, token) != have) {
printf("failed to write %ld compressed bytes to output\n",
(long)have);
return -1;
}
SHA_update(ctx, temp_data, have);
} while (ret != Z_STREAM_END);
deflateEnd(&strm);
free(temp_data);
free(uncompressed_target_data);
} else {
printf("patch chunk %d is unknown type %d\n", i, type);
return -1;
}
}
return 0;
}