/*
* 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.cpp in this directory for a description of the patch file
// format.
#include <applypatch/imgpatch.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/stat.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include <android-base/logging.h>
#include <android-base/memory.h>
#include <applypatch/applypatch.h>
#include <applypatch/imgdiff.h>
#include <openssl/sha.h>
#include <zlib.h>
#include "edify/expr.h"
static inline int64_t Read8(const void *address) {
return android::base::get_unaligned<int64_t>(address);
}
static inline int32_t Read4(const void *address) {
return android::base::get_unaligned<int32_t>(address);
}
// This function is a wrapper of ApplyBSDiffPatch(). It has a custom sink function to deflate the
// patched data and stream the deflated data to output.
static bool ApplyBSDiffPatchAndStreamOutput(const uint8_t* src_data, size_t src_len,
const Value* patch, size_t patch_offset,
const char* deflate_header, SinkFn sink, SHA_CTX* ctx) {
size_t expected_target_length = static_cast<size_t>(Read8(deflate_header + 32));
int level = Read4(deflate_header + 40);
int method = Read4(deflate_header + 44);
int window_bits = Read4(deflate_header + 48);
int mem_level = Read4(deflate_header + 52);
int strategy = Read4(deflate_header + 56);
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = nullptr;
int ret = deflateInit2(&strm, level, method, window_bits, mem_level, strategy);
if (ret != Z_OK) {
LOG(ERROR) << "Failed to init uncompressed data deflation: " << ret;
return false;
}
// Define a custom sink wrapper that feeds to bspatch. It deflates the available patch data on
// the fly and outputs the compressed data to the given sink.
size_t actual_target_length = 0;
size_t total_written = 0;
static constexpr size_t buffer_size = 32768;
auto compression_sink = [&strm, &actual_target_length, &expected_target_length, &total_written,
&ret, &ctx, &sink](const uint8_t* data, size_t len) -> size_t {
// The input patch length for an update never exceeds INT_MAX.
strm.avail_in = len;
strm.next_in = data;
do {
std::vector<uint8_t> buffer(buffer_size);
strm.avail_out = buffer_size;
strm.next_out = buffer.data();
if (actual_target_length + len < expected_target_length) {
ret = deflate(&strm, Z_NO_FLUSH);
} else {
ret = deflate(&strm, Z_FINISH);
}
if (ret != Z_OK && ret != Z_STREAM_END) {
LOG(ERROR) << "Failed to deflate stream: " << ret;
// zero length indicates an error in the sink function of bspatch().
return 0;
}
size_t have = buffer_size - strm.avail_out;
total_written += have;
if (sink(buffer.data(), have) != have) {
LOG(ERROR) << "Failed to write " << have << " compressed bytes to output.";
return 0;
}
if (ctx) SHA1_Update(ctx, buffer.data(), have);
} while ((strm.avail_in != 0 || strm.avail_out == 0) && ret != Z_STREAM_END);
actual_target_length += len;
return len;
};
int bspatch_result =
ApplyBSDiffPatch(src_data, src_len, patch, patch_offset, compression_sink, nullptr);
deflateEnd(&strm);
if (bspatch_result != 0) {
return false;
}
if (ret != Z_STREAM_END) {
LOG(ERROR) << "ret is expected to be Z_STREAM_END, but it's " << ret;
return false;
}
if (expected_target_length != actual_target_length) {
LOG(ERROR) << "target length is expected to be " << expected_target_length << ", but it's "
<< actual_target_length;
return false;
}
LOG(DEBUG) << "bspatch writes " << total_written << " bytes in total to streaming output.";
return true;
}
int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const unsigned char* patch_data,
size_t patch_size, SinkFn sink) {
Value patch(VAL_BLOB, std::string(reinterpret_cast<const char*>(patch_data), patch_size));
return ApplyImagePatch(old_data, old_size, &patch, sink, nullptr, nullptr);
}
/*
* 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, size_t old_size, const Value* patch, SinkFn sink,
SHA_CTX* ctx, const Value* bonus_data) {
if (patch->data.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.)
size_t pos = 12;
const char* header = &patch->data[0];
if (memcmp(header, "IMGDIFF2", 8) != 0) {
printf("corrupt patch file header (magic number)\n");
return -1;
}
int num_chunks = Read4(header + 8);
for (int i = 0; i < num_chunks; ++i) {
// each chunk's header record starts with 4 bytes.
if (pos + 4 > patch->data.size()) {
printf("failed to read chunk %d record\n", i);
return -1;
}
int type = Read4(&patch->data[pos]);
pos += 4;
if (type == CHUNK_NORMAL) {
const char* normal_header = &patch->data[pos];
pos += 24;
if (pos > patch->data.size()) {
printf("failed to read chunk %d normal header data\n", i);
return -1;
}
size_t src_start = static_cast<size_t>(Read8(normal_header));
size_t src_len = static_cast<size_t>(Read8(normal_header + 8));
size_t patch_offset = static_cast<size_t>(Read8(normal_header + 16));
if (src_start + src_len > old_size) {
printf("source data too short\n");
return -1;
}
if (ApplyBSDiffPatch(old_data + src_start, src_len, patch, patch_offset, sink, ctx) != 0) {
printf("Failed to apply bsdiff patch.\n");
return -1;
}
} else if (type == CHUNK_RAW) {
const char* raw_header = &patch->data[pos];
pos += 4;
if (pos > patch->data.size()) {
printf("failed to read chunk %d raw header data\n", i);
return -1;
}
size_t data_len = static_cast<size_t>(Read4(raw_header));
if (pos + data_len > patch->data.size()) {
printf("failed to read chunk %d raw data\n", i);
return -1;
}
if (ctx) SHA1_Update(ctx, &patch->data[pos], data_len);
if (sink(reinterpret_cast<const unsigned char*>(&patch->data[pos]), data_len) != 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.
const char* deflate_header = &patch->data[pos];
pos += 60;
if (pos > patch->data.size()) {
printf("failed to read chunk %d deflate header data\n", i);
return -1;
}
size_t src_start = static_cast<size_t>(Read8(deflate_header));
size_t src_len = static_cast<size_t>(Read8(deflate_header + 8));
size_t patch_offset = static_cast<size_t>(Read8(deflate_header + 16));
size_t expanded_len = static_cast<size_t>(Read8(deflate_header + 24));
if (src_start + src_len > old_size) {
printf("source data too short\n");
return -1;
}
// Decompress the source data; the chunk header tells us exactly
// how big we expect it to be when decompressed.
// Note: expanded_len will include the bonus data size if
// the patch was constructed with bonus data. The
// deflation will come up 'bonus_size' bytes short; these
// must be appended from the bonus_data value.
size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->data.size() : 0;
std::vector<unsigned char> expanded_source(expanded_len);
// inflate() doesn't like strm.next_out being a nullptr even with
// avail_out being zero (Z_STREAM_ERROR).
if (expanded_len != 0) {
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = src_len;
strm.next_in = old_data + src_start;
strm.avail_out = expanded_len;
strm.next_out = expanded_source.data();
int 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, except
// for the bonus_size.
if (strm.avail_out != bonus_size) {
printf("source inflation short by %zu bytes\n", strm.avail_out - bonus_size);
return -1;
}
inflateEnd(&strm);
if (bonus_size) {
memcpy(expanded_source.data() + (expanded_len - bonus_size), &bonus_data->data[0],
bonus_size);
}
}
if (!ApplyBSDiffPatchAndStreamOutput(expanded_source.data(), expanded_len, patch,
patch_offset, deflate_header, sink, ctx)) {
LOG(ERROR) << "Fail to apply streaming bspatch.";
return -1;
}
} else {
printf("patch chunk %d is unknown type %d\n", i, type);
return -1;
}
}
return 0;
}
