/*
* 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.
*
* This tool can take an optional file of "bonus data". This is an
* extra file of data that is appended to chunk #1 after it is
* compressed (it must be a CHUNK_DEFLATE chunk). The same file must
* be available (and passed to applypatch with -b) when applying the
* patch. This is used to reduce the size of recovery-from-boot
* patches by combining the boot image with recovery ramdisk
* information that is stored on the system partition.
*/
#include "applypatch/imgdiff.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <algorithm>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/memory.h>
#include <android-base/unique_fd.h>
#include <ziparchive/zip_archive.h>
#include <bsdiff.h>
#include <zlib.h>
using android::base::get_unaligned;
static constexpr auto BUFFER_SIZE = 0x8000;
// If we use this function to write the offset and length (type size_t), their values should not
// exceed 2^63; because the signed bit will be casted away.
static inline bool Write8(int fd, int64_t value) {
return android::base::WriteFully(fd, &value, sizeof(int64_t));
}
// Similarly, the value should not exceed 2^31 if we are casting from size_t (e.g. target chunk
// size).
static inline bool Write4(int fd, int32_t value) {
return android::base::WriteFully(fd, &value, sizeof(int32_t));
}
class ImageChunk {
public:
static constexpr auto WINDOWBITS = -15; // 32kb window; negative to indicate a raw stream.
static constexpr auto MEMLEVEL = 8; // the default value.
static constexpr auto METHOD = Z_DEFLATED;
static constexpr auto STRATEGY = Z_DEFAULT_STRATEGY;
ImageChunk(int type, size_t start, const std::vector<uint8_t>* file_content, size_t raw_data_len,
std::string entry_name = {})
: type_(type),
start_(start),
input_file_ptr_(file_content),
raw_data_len_(raw_data_len),
compress_level_(6),
entry_name_(std::move(entry_name)) {
CHECK(file_content != nullptr) << "input file container can't be nullptr";
}
int GetType() const {
return type_;
}
size_t GetRawDataLength() const {
return raw_data_len_;
}
const std::string& GetEntryName() const {
return entry_name_;
}
size_t GetStartOffset() const {
return start_;
}
int GetCompressLevel() const {
return compress_level_;
}
// CHUNK_DEFLATE will return the uncompressed data for diff, while other types will simply return
// the raw data.
const uint8_t * DataForPatch() const;
size_t DataLengthForPatch() const;
void Dump() const {
printf("type: %d, start: %zu, len: %zu, name: %s\n", type_, start_, DataLengthForPatch(),
entry_name_.c_str());
}
void SetUncompressedData(std::vector<uint8_t> data);
bool SetBonusData(const std::vector<uint8_t>& bonus_data);
bool operator==(const ImageChunk& other) const;
bool operator!=(const ImageChunk& other) const {
return !(*this == other);
}
/*
* 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();
/*
* 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.
*/
bool ReconstructDeflateChunk();
bool IsAdjacentNormal(const ImageChunk& other) const;
void MergeAdjacentNormal(const ImageChunk& other);
/*
* Compute a bsdiff patch between |src| and |tgt|; Store the result in the patch_data.
* |bsdiff_cache| can be used to cache the suffix array if the same |src| chunk is used
* repeatedly, pass nullptr if not needed.
*/
static bool MakePatch(const ImageChunk& tgt, const ImageChunk& src,
std::vector<uint8_t>* patch_data, saidx_t** bsdiff_cache);
private:
const uint8_t* GetRawData() const;
bool TryReconstruction(int level);
int type_; // CHUNK_NORMAL, CHUNK_DEFLATE, CHUNK_RAW
size_t start_; // offset of chunk in the original input file
const std::vector<uint8_t>* input_file_ptr_; // ptr to the full content of original input file
size_t raw_data_len_;
// deflate encoder parameters
int compress_level_;
// --- for CHUNK_DEFLATE chunks only: ---
std::vector<uint8_t> uncompressed_data_;
std::string entry_name_; // used for zip entries
};
const uint8_t* ImageChunk::GetRawData() const {
CHECK_LE(start_ + raw_data_len_, input_file_ptr_->size());
return input_file_ptr_->data() + start_;
}
const uint8_t * ImageChunk::DataForPatch() const {
if (type_ == CHUNK_DEFLATE) {
return uncompressed_data_.data();
}
return GetRawData();
}
size_t ImageChunk::DataLengthForPatch() const {
if (type_ == CHUNK_DEFLATE) {
return uncompressed_data_.size();
}
return raw_data_len_;
}
bool ImageChunk::operator==(const ImageChunk& other) const {
if (type_ != other.type_) {
return false;
}
return (raw_data_len_ == other.raw_data_len_ &&
memcmp(GetRawData(), other.GetRawData(), raw_data_len_) == 0);
}
void ImageChunk::SetUncompressedData(std::vector<uint8_t> data) {
uncompressed_data_ = std::move(data);
}
bool ImageChunk::SetBonusData(const std::vector<uint8_t>& bonus_data) {
if (type_ != CHUNK_DEFLATE) {
return false;
}
uncompressed_data_.insert(uncompressed_data_.end(), bonus_data.begin(), bonus_data.end());
return true;
}
void ImageChunk::ChangeDeflateChunkToNormal() {
if (type_ != CHUNK_DEFLATE) return;
type_ = CHUNK_NORMAL;
// No need to clear the entry name.
uncompressed_data_.clear();
}
bool ImageChunk::IsAdjacentNormal(const ImageChunk& other) const {
if (type_ != CHUNK_NORMAL || other.type_ != CHUNK_NORMAL) {
return false;
}
return (other.start_ == start_ + raw_data_len_);
}
void ImageChunk::MergeAdjacentNormal(const ImageChunk& other) {
CHECK(IsAdjacentNormal(other));
raw_data_len_ = raw_data_len_ + other.raw_data_len_;
}
bool ImageChunk::MakePatch(const ImageChunk& tgt, const ImageChunk& src,
std::vector<uint8_t>* patch_data, saidx_t** bsdiff_cache) {
#if defined(__ANDROID__)
char ptemp[] = "/data/local/tmp/imgdiff-patch-XXXXXX";
#else
char ptemp[] = "/tmp/imgdiff-patch-XXXXXX";
#endif
int fd = mkstemp(ptemp);
if (fd == -1) {
printf("MakePatch failed to create a temporary file: %s\n", strerror(errno));
return false;
}
close(fd);
int r = bsdiff::bsdiff(src.DataForPatch(), src.DataLengthForPatch(), tgt.DataForPatch(),
tgt.DataLengthForPatch(), ptemp, bsdiff_cache);
if (r != 0) {
printf("bsdiff() failed: %d\n", r);
return false;
}
android::base::unique_fd patch_fd(open(ptemp, O_RDONLY));
if (patch_fd == -1) {
printf("failed to open %s: %s\n", ptemp, strerror(errno));
return false;
}
struct stat st;
if (fstat(patch_fd, &st) != 0) {
printf("failed to stat patch file %s: %s\n", ptemp, strerror(errno));
return false;
}
size_t sz = static_cast<size_t>(st.st_size);
patch_data->resize(sz);
if (!android::base::ReadFully(patch_fd, patch_data->data(), sz)) {
printf("failed to read \"%s\" %s\n", ptemp, strerror(errno));
unlink(ptemp);
return false;
}
unlink(ptemp);
return true;
}
bool ImageChunk::ReconstructDeflateChunk() {
if (type_ != CHUNK_DEFLATE) {
printf("attempt to reconstruct non-deflate chunk\n");
return false;
}
// We only check two combinations of encoder parameters: level 6 (the default) and level 9
// (the maximum).
for (int level = 6; level <= 9; level += 3) {
if (TryReconstruction(level)) {
compress_level_ = level;
return true;
}
}
return false;
}
/*
* 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).
*/
bool ImageChunk::TryReconstruction(int level) {
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = uncompressed_data_.size();
strm.next_in = uncompressed_data_.data();
int ret = deflateInit2(&strm, level, METHOD, WINDOWBITS, MEMLEVEL, STRATEGY);
if (ret < 0) {
printf("failed to initialize deflate: %d\n", ret);
return false;
}
std::vector<uint8_t> buffer(BUFFER_SIZE);
size_t offset = 0;
do {
strm.avail_out = buffer.size();
strm.next_out = buffer.data();
ret = deflate(&strm, Z_FINISH);
if (ret < 0) {
printf("failed to deflate: %d\n", ret);
return false;
}
size_t compressed_size = buffer.size() - strm.avail_out;
if (memcmp(buffer.data(), input_file_ptr_->data() + start_ + offset, compressed_size) != 0) {
// mismatch; data isn't the same.
deflateEnd(&strm);
return false;
}
offset += compressed_size;
} while (ret != Z_STREAM_END);
deflateEnd(&strm);
if (offset != raw_data_len_) {
// mismatch; ran out of data before we should have.
return false;
}
return true;
}
// PatchChunk stores the patch data between a source chunk and a target chunk. It also keeps track
// of the metadata of src&tgt chunks (e.g. offset, raw data length, uncompressed data length).
class PatchChunk {
public:
PatchChunk(const ImageChunk& tgt, const ImageChunk& src, std::vector<uint8_t> data)
: type_(tgt.GetType()),
source_start_(src.GetStartOffset()),
source_len_(src.GetRawDataLength()),
source_uncompressed_len_(src.DataLengthForPatch()),
target_start_(tgt.GetStartOffset()),
target_len_(tgt.GetRawDataLength()),
target_uncompressed_len_(tgt.DataLengthForPatch()),
target_compress_level_(tgt.GetCompressLevel()),
data_(std::move(data)) {}
// Construct a CHUNK_RAW patch from the target data directly.
explicit PatchChunk(const ImageChunk& tgt)
: type_(CHUNK_RAW),
source_start_(0),
source_len_(0),
source_uncompressed_len_(0),
target_start_(tgt.GetStartOffset()),
target_len_(tgt.GetRawDataLength()),
target_uncompressed_len_(tgt.DataLengthForPatch()),
target_compress_level_(tgt.GetCompressLevel()),
data_(tgt.DataForPatch(), tgt.DataForPatch() + tgt.DataLengthForPatch()) {}
// Return true if raw data size is smaller than the patch size.
static bool RawDataIsSmaller(const ImageChunk& tgt, size_t patch_size);
static bool WritePatchDataToFd(const std::vector<PatchChunk>& patch_chunks, int patch_fd);
private:
size_t GetHeaderSize() const;
size_t WriteHeaderToFd(int fd, size_t offset) const;
// The patch chunk type is the same as the target chunk type. The only exception is we change
// the |type_| to CHUNK_RAW if target length is smaller than the patch size.
int type_;
size_t source_start_;
size_t source_len_;
size_t source_uncompressed_len_;
size_t target_start_; // offset of the target chunk within the target file
size_t target_len_;
size_t target_uncompressed_len_;
size_t target_compress_level_; // the deflate compression level of the target chunk.
std::vector<uint8_t> data_; // storage for the patch data
};
// Return true if raw data is smaller than the patch size.
bool PatchChunk::RawDataIsSmaller(const ImageChunk& tgt, size_t patch_size) {
size_t target_len = tgt.GetRawDataLength();
return (tgt.GetType() == CHUNK_NORMAL && (target_len <= 160 || target_len < patch_size));
}
// Header size:
// header_type 4 bytes
// CHUNK_NORMAL 8*3 = 24 bytes
// CHUNK_DEFLATE 8*5 + 4*5 = 60 bytes
// CHUNK_RAW 4 bytes + patch_size
size_t PatchChunk::GetHeaderSize() const {
switch (type_) {
case CHUNK_NORMAL:
return 4 + 8 * 3;
case CHUNK_DEFLATE:
return 4 + 8 * 5 + 4 * 5;
case CHUNK_RAW:
return 4 + 4 + data_.size();
default:
CHECK(false) << "unexpected chunk type: " << type_; // Should not reach here.
return 0;
}
}
// Return the offset of the next patch into the patch data.
size_t PatchChunk::WriteHeaderToFd(int fd, size_t offset) const {
Write4(fd, type_);
switch (type_) {
case CHUNK_NORMAL:
printf("normal (%10zu, %10zu) %10zu\n", target_start_, target_len_, data_.size());
Write8(fd, static_cast<int64_t>(source_start_));
Write8(fd, static_cast<int64_t>(source_len_));
Write8(fd, static_cast<int64_t>(offset));
return offset + data_.size();
case CHUNK_DEFLATE:
printf("deflate (%10zu, %10zu) %10zu\n", target_start_, target_len_, data_.size());
Write8(fd, static_cast<int64_t>(source_start_));
Write8(fd, static_cast<int64_t>(source_len_));
Write8(fd, static_cast<int64_t>(offset));
Write8(fd, static_cast<int64_t>(source_uncompressed_len_));
Write8(fd, static_cast<int64_t>(target_uncompressed_len_));
Write4(fd, target_compress_level_);
Write4(fd, ImageChunk::METHOD);
Write4(fd, ImageChunk::WINDOWBITS);
Write4(fd, ImageChunk::MEMLEVEL);
Write4(fd, ImageChunk::STRATEGY);
return offset + data_.size();
case CHUNK_RAW:
printf("raw (%10zu, %10zu)\n", target_start_, target_len_);
Write4(fd, static_cast<int32_t>(data_.size()));
if (!android::base::WriteFully(fd, data_.data(), data_.size())) {
CHECK(false) << "failed to write " << data_.size() << " bytes patch";
}
return offset;
default:
CHECK(false) << "unexpected chunk type: " << type_;
return offset;
}
}
// Write the contents of |patch_chunks| to |patch_fd|.
bool PatchChunk::WritePatchDataToFd(const std::vector<PatchChunk>& patch_chunks, int patch_fd) {
// 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 (const auto& patch : patch_chunks) {
total_header_size += patch.GetHeaderSize();
}
size_t offset = total_header_size;
// Write out the headers.
if (!android::base::WriteStringToFd("IMGDIFF2", patch_fd)) {
printf("failed to write \"IMGDIFF2\": %s\n", strerror(errno));
return false;
}
Write4(patch_fd, static_cast<int32_t>(patch_chunks.size()));
for (size_t i = 0; i < patch_chunks.size(); ++i) {
printf("chunk %zu: ", i);
offset = patch_chunks[i].WriteHeaderToFd(patch_fd, offset);
}
// Append each chunk's bsdiff patch, in order.
for (const auto& patch : patch_chunks) {
if (patch.type_ == CHUNK_RAW) {
continue;
}
if (!android::base::WriteFully(patch_fd, patch.data_.data(), patch.data_.size())) {
printf("failed to write %zu bytes patch to patch_fd\n", patch.data_.size());
return false;
}
}
return true;
}
// Interface for zip_mode and image_mode images. We initialize the image from an input file and
// split the file content into a list of image chunks.
class Image {
public:
explicit Image(bool is_source) : is_source_(is_source) {}
virtual ~Image() {}
// Create a list of image chunks from input file.
virtual bool Initialize(const std::string& filename) = 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();
// In zip mode, find the matching deflate source chunk by entry name. Search for normal chunks
// also if |find_normal| is true.
ImageChunk* FindChunkByName(const std::string& name, bool find_normal = false);
const ImageChunk* FindChunkByName(const std::string& name, bool find_normal = false) const;
void DumpChunks() const;
// Non const iterators to access the stored ImageChunks.
std::vector<ImageChunk>::iterator begin() {
return chunks_.begin();
}
std::vector<ImageChunk>::iterator end() {
return chunks_.end();
}
ImageChunk& operator[](size_t i) {
CHECK_LT(i, chunks_.size());
return chunks_[i];
}
const ImageChunk& operator[](size_t i) const {
CHECK_LT(i, chunks_.size());
return chunks_[i];
}
size_t NumOfChunks() const {
return chunks_.size();
}
protected:
bool ReadFile(const std::string& filename, std::vector<uint8_t>* file_content);
bool is_source_; // True if it's for source chunks.
std::vector<ImageChunk> chunks_; // Internal storage of ImageChunk.
std::vector<uint8_t> file_content_; // Store the whole input file in memory.
};
void Image::MergeAdjacentNormalChunks() {
size_t merged_last = 0, cur = 0;
while (cur < chunks_.size()) {
// Look for normal chunks adjacent to the current one. If such chunk exists, extend the
// length of the current normal chunk.
size_t to_check = cur + 1;
while (to_check < chunks_.size() && chunks_[cur].IsAdjacentNormal(chunks_[to_check])) {
chunks_[cur].MergeAdjacentNormal(chunks_[to_check]);
to_check++;
}
if (merged_last != cur) {
chunks_[merged_last] = std::move(chunks_[cur]);
}
merged_last++;
cur = to_check;
}
if (merged_last < chunks_.size()) {
chunks_.erase(chunks_.begin() + merged_last, chunks_.end());
}
}
const ImageChunk* Image::FindChunkByName(const std::string& name, bool find_normal) const {
if (name.empty()) {
return nullptr;
}
for (auto& chunk : chunks_) {
if ((chunk.GetType() == CHUNK_DEFLATE || find_normal) && chunk.GetEntryName() == name) {
return &chunk;
}
}
return nullptr;
}
ImageChunk* Image::FindChunkByName(const std::string& name, bool find_normal) {
return const_cast<ImageChunk*>(
static_cast<const Image*>(this)->FindChunkByName(name, find_normal));
}
void Image::DumpChunks() const {
std::string type = is_source_ ? "source" : "target";
printf("Dumping chunks for %s\n", type.c_str());
for (size_t i = 0; i < chunks_.size(); ++i) {
printf("chunk %zu: ", i);
chunks_[i].Dump();
}
}
bool Image::ReadFile(const std::string& filename, std::vector<uint8_t>* file_content) {
CHECK(file_content != nullptr);
android::base::unique_fd fd(open(filename.c_str(), O_RDONLY));
if (fd == -1) {
printf("failed to open \"%s\" %s\n", filename.c_str(), strerror(errno));
return false;
}
struct stat st;
if (fstat(fd, &st) != 0) {
printf("failed to stat \"%s\": %s\n", filename.c_str(), strerror(errno));
return false;
}
size_t sz = static_cast<size_t>(st.st_size);
file_content->resize(sz);
if (!android::base::ReadFully(fd, file_content->data(), sz)) {
printf("failed to read \"%s\" %s\n", filename.c_str(), strerror(errno));
return false;
}
fd.reset();
return true;
}
class ZipModeImage : public Image {
public:
explicit ZipModeImage(bool is_source) : Image(is_source) {}
bool Initialize(const std::string& filename) override;
const ImageChunk& PseudoSource() const {
CHECK(is_source_);
CHECK(pseudo_source_ != nullptr);
return *pseudo_source_;
}
// Verify that we can reconstruct the deflate chunks; also change the type to CHUNK_NORMAL if
// src and tgt are identical.
static bool CheckAndProcessChunks(ZipModeImage* tgt_image, ZipModeImage* src_image);
// Compute the patch between tgt & src images, and write the data into |patch_name|.
static bool GeneratePatches(const ZipModeImage& tgt_image, const ZipModeImage& src_image,
const std::string& patch_name);
private:
// Initialize image chunks based on the zip entries.
bool InitializeChunks(const std::string& filename, ZipArchiveHandle handle);
// Add the a zip entry to the list.
bool AddZipEntryToChunks(ZipArchiveHandle handle, const std::string& entry_name, ZipEntry* entry);
// Return the real size of the zip file. (omit the trailing zeros that used for alignment)
bool GetZipFileSize(size_t* input_file_size);
// The pesudo source chunk for bsdiff if there's no match for the given target chunk. It's in
// fact the whole source file.
std::unique_ptr<ImageChunk> pseudo_source_;
};
bool ZipModeImage::Initialize(const std::string& filename) {
if (!ReadFile(filename, &file_content_)) {
return false;
}
// Omit the trailing zeros before we pass the file to ziparchive handler.
size_t zipfile_size;
if (!GetZipFileSize(&zipfile_size)) {
printf("failed to parse the actual size of %s\n", filename.c_str());
return false;
}
ZipArchiveHandle handle;
int err = OpenArchiveFromMemory(const_cast<uint8_t*>(file_content_.data()), zipfile_size,
filename.c_str(), &handle);
if (err != 0) {
printf("failed to open zip file %s: %s\n", filename.c_str(), ErrorCodeString(err));
CloseArchive(handle);
return false;
}
if (is_source_) {
pseudo_source_ = std::make_unique<ImageChunk>(CHUNK_NORMAL, 0, &file_content_, zipfile_size);
}
if (!InitializeChunks(filename, handle)) {
CloseArchive(handle);
return false;
}
CloseArchive(handle);
return true;
}
// Iterate the zip entries and compose the image chunks accordingly.
bool ZipModeImage::InitializeChunks(const std::string& filename, ZipArchiveHandle handle) {
void* cookie;
int ret = StartIteration(handle, &cookie, nullptr, nullptr);
if (ret != 0) {
printf("failed to iterate over entries in %s: %s\n", filename.c_str(), ErrorCodeString(ret));
return false;
}
// Create a list of deflated zip entries, sorted by offset.
std::vector<std::pair<std::string, ZipEntry>> temp_entries;
ZipString name;
ZipEntry entry;
while ((ret = Next(cookie, &entry, &name)) == 0) {
if (entry.method == kCompressDeflated) {
std::string entry_name(name.name, name.name + name.name_length);
temp_entries.emplace_back(entry_name, entry);
}
}
if (ret != -1) {
printf("Error while iterating over zip entries: %s\n", ErrorCodeString(ret));
return false;
}
std::sort(temp_entries.begin(), temp_entries.end(),
[](auto& entry1, auto& entry2) { return entry1.second.offset < entry2.second.offset; });
EndIteration(cookie);
// For source chunks, we don't need to compose chunks for the metadata.
if (is_source_) {
for (auto& entry : temp_entries) {
if (!AddZipEntryToChunks(handle, entry.first, &entry.second)) {
printf("Failed to add %s to source chunks\n", entry.first.c_str());
return false;
}
}
return true;
}
// For target chunks, add the deflate entries as CHUNK_DEFLATE and the contents between two
// deflate entries as CHUNK_NORMAL.
size_t pos = 0;
size_t nextentry = 0;
while (pos < file_content_.size()) {
if (nextentry < temp_entries.size() &&
static_cast<off64_t>(pos) == temp_entries[nextentry].second.offset) {
// Add the next zip entry.
std::string entry_name = temp_entries[nextentry].first;
if (!AddZipEntryToChunks(handle, entry_name, &temp_entries[nextentry].second)) {
printf("Failed to add %s to target chunks\n", entry_name.c_str());
return false;
}
pos += temp_entries[nextentry].second.compressed_length;
++nextentry;
continue;
}
// Use a normal chunk to take all the data up to the start of the next entry.
size_t raw_data_len;
if (nextentry < temp_entries.size()) {
raw_data_len = temp_entries[nextentry].second.offset - pos;
} else {
raw_data_len = file_content_.size() - pos;
}
chunks_.emplace_back(CHUNK_NORMAL, pos, &file_content_, raw_data_len);
pos += raw_data_len;
}
return true;
}
bool ZipModeImage::AddZipEntryToChunks(ZipArchiveHandle handle, const std::string& entry_name,
ZipEntry* entry) {
size_t compressed_len = entry->compressed_length;
if (entry->method == kCompressDeflated) {
size_t uncompressed_len = entry->uncompressed_length;
std::vector<uint8_t> uncompressed_data(uncompressed_len);
int ret = ExtractToMemory(handle, entry, uncompressed_data.data(), uncompressed_len);
if (ret != 0) {
printf("failed to extract %s with size %zu: %s\n", entry_name.c_str(), uncompressed_len,
ErrorCodeString(ret));
return false;
}
ImageChunk curr(CHUNK_DEFLATE, entry->offset, &file_content_, compressed_len, entry_name);
curr.SetUncompressedData(std::move(uncompressed_data));
chunks_.push_back(std::move(curr));
} else {
chunks_.emplace_back(CHUNK_NORMAL, entry->offset, &file_content_, compressed_len, entry_name);
}
return true;
}
// EOCD record
// offset 0: signature 0x06054b50, 4 bytes
// offset 4: number of this disk, 2 bytes
// ...
// offset 20: comment length, 2 bytes
// offset 22: comment, n bytes
bool ZipModeImage::GetZipFileSize(size_t* input_file_size) {
if (file_content_.size() < 22) {
printf("file is too small to be a zip file\n");
return false;
}
// Look for End of central directory record of the zip file, and calculate the actual
// zip_file size.
for (int i = file_content_.size() - 22; i >= 0; i--) {
if (file_content_[i] == 0x50) {
if (get_unaligned<uint32_t>(&file_content_[i]) == 0x06054b50) {
// double-check: this archive consists of a single "disk".
CHECK_EQ(get_unaligned<uint16_t>(&file_content_[i + 4]), 0);
uint16_t comment_length = get_unaligned<uint16_t>(&file_content_[i + 20]);
size_t file_size = i + 22 + comment_length;
CHECK_LE(file_size, file_content_.size());
*input_file_size = file_size;
return true;
}
}
}
// EOCD not found, this file is likely not a valid zip file.
return false;
}
bool ZipModeImage::CheckAndProcessChunks(ZipModeImage* tgt_image, ZipModeImage* src_image) {
for (auto& tgt_chunk : *tgt_image) {
if (tgt_chunk.GetType() != CHUNK_DEFLATE) {
continue;
}
ImageChunk* src_chunk = src_image->FindChunkByName(tgt_chunk.GetEntryName());
if (src_chunk == nullptr) {
tgt_chunk.ChangeDeflateChunkToNormal();
} else if (tgt_chunk == *src_chunk) {
// 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.
tgt_chunk.ChangeDeflateChunkToNormal();
src_chunk->ChangeDeflateChunkToNormal();
} else if (!tgt_chunk.ReconstructDeflateChunk()) {
// We cannot recompress the data and get exactly the same bits as are in the input target
// image. Treat the chunk as a normal non-deflated chunk.
printf("failed to reconstruct target deflate chunk [%s]; treating as normal\n",
tgt_chunk.GetEntryName().c_str());
tgt_chunk.ChangeDeflateChunkToNormal();
src_chunk->ChangeDeflateChunkToNormal();
}
}
// For zips, we only need merge normal chunks for the target: deflated chunks are matched via
// filename, and normal chunks are patched using the entire source file as the source.
tgt_image->MergeAdjacentNormalChunks();
tgt_image->DumpChunks();
return true;
}
bool ZipModeImage::GeneratePatches(const ZipModeImage& tgt_image, const ZipModeImage& src_image,
const std::string& patch_name) {
printf("Construct patches for %zu chunks...\n", tgt_image.NumOfChunks());
std::vector<PatchChunk> patch_chunks;
patch_chunks.reserve(tgt_image.NumOfChunks());
saidx_t* bsdiff_cache = nullptr;
for (size_t i = 0; i < tgt_image.NumOfChunks(); i++) {
const auto& tgt_chunk = tgt_image[i];
if (PatchChunk::RawDataIsSmaller(tgt_chunk, 0)) {
patch_chunks.emplace_back(tgt_chunk);
continue;
}
const ImageChunk* src_chunk = (tgt_chunk.GetType() != CHUNK_DEFLATE)
? nullptr
: src_image.FindChunkByName(tgt_chunk.GetEntryName());
const auto& src_ref = (src_chunk == nullptr) ? src_image.PseudoSource() : *src_chunk;
saidx_t** bsdiff_cache_ptr = (src_chunk == nullptr) ? &bsdiff_cache : nullptr;
std::vector<uint8_t> patch_data;
if (!ImageChunk::MakePatch(tgt_chunk, src_ref, &patch_data, bsdiff_cache_ptr)) {
printf("Failed to generate patch, name: %s\n", tgt_chunk.GetEntryName().c_str());
return false;
}
printf("patch %3zu is %zu bytes (of %zu)\n", i, patch_data.size(),
tgt_chunk.GetRawDataLength());
if (PatchChunk::RawDataIsSmaller(tgt_chunk, patch_data.size())) {
patch_chunks.emplace_back(tgt_chunk);
} else {
patch_chunks.emplace_back(tgt_chunk, src_ref, std::move(patch_data));
}
}
free(bsdiff_cache);
CHECK_EQ(tgt_image.NumOfChunks(), patch_chunks.size());
android::base::unique_fd patch_fd(
open(patch_name.c_str(), O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR));
if (patch_fd == -1) {
printf("failed to open \"%s\": %s\n", patch_name.c_str(), strerror(errno));
return false;
}
return PatchChunk::WritePatchDataToFd(patch_chunks, patch_fd);
}
class ImageModeImage : public Image {
public:
explicit ImageModeImage(bool is_source) : Image(is_source) {}
// Initialize the image chunks list by searching the magic numbers in an image file.
bool Initialize(const std::string& filename) override;
bool SetBonusData(const std::vector<uint8_t>& bonus_data);
// In Image Mode, verify that the source and target images have the same chunk structure (ie, the
// same sequence of deflate and normal chunks).
static bool CheckAndProcessChunks(ImageModeImage* tgt_image, ImageModeImage* src_image);
// In image mode, generate patches against the given source chunks and bonus_data; write the
// result to |patch_name|.
static bool GeneratePatches(const ImageModeImage& tgt_image, const ImageModeImage& src_image,
const std::string& patch_name);
};
bool ImageModeImage::Initialize(const std::string& filename) {
if (!ReadFile(filename, &file_content_)) {
return false;
}
size_t sz = file_content_.size();
size_t pos = 0;
while (pos < sz) {
// 0x00 no header flags, 0x08 deflate compression, 0x1f8b gzip magic number
if (sz - pos >= 4 && get_unaligned<uint32_t>(file_content_.data() + pos) == 0x00088b1f) {
// 'pos' is the offset of the start of a gzip chunk.
size_t chunk_offset = pos;
// The remaining data is too small to be a gzip chunk; treat them as a normal chunk.
if (sz - pos < GZIP_HEADER_LEN + GZIP_FOOTER_LEN) {
chunks_.emplace_back(CHUNK_NORMAL, pos, &file_content_, sz - pos);
break;
}
// We need three chunks for the deflated image in total, one normal chunk for the header,
// one deflated chunk for the body, and another normal chunk for the footer.
chunks_.emplace_back(CHUNK_NORMAL, pos, &file_content_, GZIP_HEADER_LEN);
pos += GZIP_HEADER_LEN;
// We must decompress this chunk in order to discover where it ends, and so we can update
// the uncompressed_data of the image body and its length.
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = sz - pos;
strm.next_in = file_content_.data() + pos;
// -15 means we are decoding a 'raw' deflate stream; zlib will
// not expect zlib headers.
int ret = inflateInit2(&strm, -15);
if (ret < 0) {
printf("failed to initialize inflate: %d\n", ret);
return false;
}
size_t allocated = BUFFER_SIZE;
std::vector<uint8_t> uncompressed_data(allocated);
size_t uncompressed_len = 0, raw_data_len = 0;
do {
strm.avail_out = allocated - uncompressed_len;
strm.next_out = uncompressed_data.data() + uncompressed_len;
ret = inflate(&strm, Z_NO_FLUSH);
if (ret < 0) {
printf("Warning: inflate failed [%s] at offset [%zu], treating as a normal chunk\n",
strm.msg, chunk_offset);
break;
}
uncompressed_len = allocated - strm.avail_out;
if (strm.avail_out == 0) {
allocated *= 2;
uncompressed_data.resize(allocated);
}
} while (ret != Z_STREAM_END);
raw_data_len = sz - strm.avail_in - pos;
inflateEnd(&strm);
if (ret < 0) {
continue;
}
// The footer 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_index = pos + raw_data_len + GZIP_FOOTER_LEN - 4;
if (sz - footer_index < 4) {
printf("Warning: invalid footer position; treating as a nomal chunk\n");
continue;
}
size_t footer_size = get_unaligned<uint32_t>(file_content_.data() + footer_index);
if (footer_size != uncompressed_len) {
printf("Warning: footer size %zu != decompressed size %zu; treating as a nomal chunk\n",
footer_size, uncompressed_len);
continue;
}
ImageChunk body(CHUNK_DEFLATE, pos, &file_content_, raw_data_len);
uncompressed_data.resize(uncompressed_len);
body.SetUncompressedData(std::move(uncompressed_data));
chunks_.push_back(std::move(body));
pos += raw_data_len;
// create a normal chunk for the footer
chunks_.emplace_back(CHUNK_NORMAL, pos, &file_content_, GZIP_FOOTER_LEN);
pos += GZIP_FOOTER_LEN;
} else {
// Use a normal chunk to take all the contents until the next gzip chunk (or EOF); we expect
// the number of chunks to be small (5 for typical boot and recovery images).
// Scan forward until we find a gzip header.
size_t data_len = 0;
while (data_len + pos < sz) {
if (data_len + pos + 4 <= sz &&
get_unaligned<uint32_t>(file_content_.data() + pos + data_len) == 0x00088b1f) {
break;
}
data_len++;
}
chunks_.emplace_back(CHUNK_NORMAL, pos, &file_content_, data_len);
pos += data_len;
}
}
return true;
}
bool ImageModeImage::SetBonusData(const std::vector<uint8_t>& bonus_data) {
CHECK(is_source_);
if (chunks_.size() < 2 || !chunks_[1].SetBonusData(bonus_data)) {
printf("Failed to set bonus data\n");
DumpChunks();
return false;
}
printf(" using %zu bytes of bonus data\n", bonus_data.size());
return true;
}
// In Image Mode, verify that the source and target images have the same chunk structure (ie, the
// same sequence of deflate and normal chunks).
bool ImageModeImage::CheckAndProcessChunks(ImageModeImage* tgt_image, ImageModeImage* src_image) {
// In image mode, merge the gzip header and footer in with any adjacent normal chunks.
tgt_image->MergeAdjacentNormalChunks();
src_image->MergeAdjacentNormalChunks();
if (tgt_image->NumOfChunks() != src_image->NumOfChunks()) {
printf("source and target don't have same number of chunks!\n");
tgt_image->DumpChunks();
src_image->DumpChunks();
return false;
}
for (size_t i = 0; i < tgt_image->NumOfChunks(); ++i) {
if ((*tgt_image)[i].GetType() != (*src_image)[i].GetType()) {
printf("source and target don't have same chunk structure! (chunk %zu)\n", i);
tgt_image->DumpChunks();
src_image->DumpChunks();
return false;
}
}
for (size_t i = 0; i < tgt_image->NumOfChunks(); ++i) {
auto& tgt_chunk = (*tgt_image)[i];
auto& src_chunk = (*src_image)[i];
if (tgt_chunk.GetType() != CHUNK_DEFLATE) {
continue;
}
// If two deflate chunks are identical treat them as normal chunks.
if (tgt_chunk == src_chunk) {
tgt_chunk.ChangeDeflateChunkToNormal();
src_chunk.ChangeDeflateChunkToNormal();
} else if (!tgt_chunk.ReconstructDeflateChunk()) {
// We cannot recompress the data and get exactly the same bits as are in the input target
// image, fall back to normal
printf("failed to reconstruct target deflate chunk %zu [%s]; treating as normal\n", i,
tgt_chunk.GetEntryName().c_str());
tgt_chunk.ChangeDeflateChunkToNormal();
src_chunk.ChangeDeflateChunkToNormal();
}
}
// For images, we need to maintain the parallel structure of the chunk lists, so do the merging
// in both the source and target lists.
tgt_image->MergeAdjacentNormalChunks();
src_image->MergeAdjacentNormalChunks();
if (tgt_image->NumOfChunks() != src_image->NumOfChunks()) {
// This shouldn't happen.
printf("merging normal chunks went awry\n");
return false;
}
return true;
}
// In image mode, generate patches against the given source chunks and bonus_data; write the
// result to |patch_name|.
bool ImageModeImage::GeneratePatches(const ImageModeImage& tgt_image,
const ImageModeImage& src_image,
const std::string& patch_name) {
printf("Construct patches for %zu chunks...\n", tgt_image.NumOfChunks());
std::vector<PatchChunk> patch_chunks;
patch_chunks.reserve(tgt_image.NumOfChunks());
for (size_t i = 0; i < tgt_image.NumOfChunks(); i++) {
const auto& tgt_chunk = tgt_image[i];
const auto& src_chunk = src_image[i];
if (PatchChunk::RawDataIsSmaller(tgt_chunk, 0)) {
patch_chunks.emplace_back(tgt_chunk);
continue;
}
std::vector<uint8_t> patch_data;
if (!ImageChunk::MakePatch(tgt_chunk, src_chunk, &patch_data, nullptr)) {
printf("Failed to generate patch for target chunk %zu: ", i);
return false;
}
printf("patch %3zu is %zu bytes (of %zu)\n", i, patch_data.size(),
tgt_chunk.GetRawDataLength());
if (PatchChunk::RawDataIsSmaller(tgt_chunk, patch_data.size())) {
patch_chunks.emplace_back(tgt_chunk);
} else {
patch_chunks.emplace_back(tgt_chunk, src_chunk, std::move(patch_data));
}
}
CHECK_EQ(tgt_image.NumOfChunks(), patch_chunks.size());
android::base::unique_fd patch_fd(
open(patch_name.c_str(), O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR));
if (patch_fd == -1) {
printf("failed to open \"%s\": %s\n", patch_name.c_str(), strerror(errno));
return false;
}
return PatchChunk::WritePatchDataToFd(patch_chunks, patch_fd);
}
int imgdiff(int argc, const char** argv) {
bool zip_mode = false;
std::vector<uint8_t> bonus_data;
int opt;
optind = 1; // Reset the getopt state so that we can call it multiple times for test.
while ((opt = getopt(argc, const_cast<char**>(argv), "zb:")) != -1) {
switch (opt) {
case 'z':
zip_mode = true;
break;
case 'b': {
android::base::unique_fd fd(open(optarg, O_RDONLY));
if (fd == -1) {
printf("failed to open bonus file %s: %s\n", optarg, strerror(errno));
return 1;
}
struct stat st;
if (fstat(fd, &st) != 0) {
printf("failed to stat bonus file %s: %s\n", optarg, strerror(errno));
return 1;
}
size_t bonus_size = st.st_size;
bonus_data.resize(bonus_size);
if (!android::base::ReadFully(fd, bonus_data.data(), bonus_size)) {
printf("failed to read bonus file %s: %s\n", optarg, strerror(errno));
return 1;
}
break;
}
default:
printf("unexpected opt: %s\n", optarg);
return 2;
}
}
if (argc - optind != 3) {
printf("usage: %s [-z] [-b <bonus-file>] <src-img> <tgt-img> <patch-file>\n", argv[0]);
return 2;
}
if (zip_mode) {
ZipModeImage src_image(true);
ZipModeImage tgt_image(false);
if (!src_image.Initialize(argv[optind])) {
return 1;
}
if (!tgt_image.Initialize(argv[optind + 1])) {
return 1;
}
if (!ZipModeImage::CheckAndProcessChunks(&tgt_image, &src_image)) {
return 1;
}
// Compute bsdiff patches for each chunk's data (the uncompressed data, in the case of
// deflate chunks).
if (!ZipModeImage::GeneratePatches(tgt_image, src_image, argv[optind + 2])) {
return 1;
}
} else {
ImageModeImage src_image(true);
ImageModeImage tgt_image(false);
if (!src_image.Initialize(argv[optind])) {
return 1;
}
if (!tgt_image.Initialize(argv[optind + 1])) {
return 1;
}
if (!ImageModeImage::CheckAndProcessChunks(&tgt_image, &src_image)) {
return 1;
}
if (!bonus_data.empty() && !src_image.SetBonusData(bonus_data)) {
return 1;
}
if (!ImageModeImage::GeneratePatches(tgt_image, src_image, argv[optind + 2])) {
return 1;
}
}
return 0;
}
