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* Copyright (C) 2017 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <stddef.h>
#include <stdio.h>
#include <sys/types.h>
#include <string>
#include <vector>
#include <bsdiff/bsdiff.h>
#include <ziparchive/zip_archive.h>
#include <zlib.h>
#include "imgdiff.h"
#include "otautil/rangeset.h"
class ImageChunk {
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 = {});
int GetType() const {
return type_;
const uint8_t* GetRawData() const;
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(size_t index) const;
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,
bsdiff::SuffixArrayIndexInterface** bsdiff_cache);
bool TryReconstruction(int level);
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
// 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 {
PatchChunk(const ImageChunk& tgt, const ImageChunk& src, std::vector<uint8_t> data);
// Construct a CHUNK_RAW patch from the target data directly.
explicit PatchChunk(const ImageChunk& tgt);
// Return true if raw data size is smaller than the patch size.
static bool RawDataIsSmaller(const ImageChunk& tgt, size_t patch_size);
// Update the source start with the new offset within the source range.
void UpdateSourceOffset(const SortedRangeSet& src_range);
// Return the total size (header + data) of the patch.
size_t PatchSize() const;
static bool WritePatchDataToFd(const std::vector<PatchChunk>& patch_chunks, int patch_fd);
size_t GetHeaderSize() const;
size_t WriteHeaderToFd(int fd, size_t offset, size_t index) 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
// 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 {
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();
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();
std::vector<ImageChunk>::const_iterator cbegin() const {
return chunks_.cbegin();
std::vector<ImageChunk>::const_iterator cend() const {
return chunks_.cend();
ImageChunk& operator[](size_t i);
const ImageChunk& operator[](size_t i) const;
size_t NumOfChunks() const {
return chunks_.size();
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.
class ZipModeImage : public Image {
explicit ZipModeImage(bool is_source, size_t limit = 0) : Image(is_source), limit_(limit) {}
bool Initialize(const std::string& filename) override;
// Initialize a dummy ZipModeImage from an existing ImageChunk vector. For src img pieces, we
// reconstruct a new file_content based on the source ranges; but it's not needed for the tgt img
// pieces; because for each chunk both the data and their offset within the file are unchanged.
void Initialize(const std::vector<ImageChunk>& chunks, const std::vector<uint8_t>& file_content) {
chunks_ = chunks;
file_content_ = file_content;
// The pesudo source chunk for bsdiff if there's no match for the given target chunk. It's in
// fact the whole source file.
ImageChunk PseudoSource() const;
// 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;
// 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);
// Compute the patch based on the lists of split src and tgt images. Generate patches for each
// pair of split pieces and write the data to |patch_name|. If |debug_dir| is specified, write
// each split src data and patch data into that directory.
static bool GeneratePatches(const std::vector<ZipModeImage>& split_tgt_images,
const std::vector<ZipModeImage>& split_src_images,
const std::vector<SortedRangeSet>& split_src_ranges,
const std::string& patch_name, const std::string& split_info_file,
const std::string& debug_dir);
// Split the tgt chunks and src chunks based on the size limit.
static bool SplitZipModeImageWithLimit(const ZipModeImage& tgt_image,
const ZipModeImage& src_image,
std::vector<ZipModeImage>* split_tgt_images,
std::vector<ZipModeImage>* split_src_images,
std::vector<SortedRangeSet>* split_src_ranges);
// 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);
static void ValidateSplitImages(const std::vector<ZipModeImage>& split_tgt_images,
const std::vector<ZipModeImage>& split_src_images,
std::vector<SortedRangeSet>& split_src_ranges,
size_t total_tgt_size);
// Construct the dummy split images based on the chunks info and source ranges; and move them into
// the given vectors. Return true if we add a new split image into |split_tgt_images|, and
// false otherwise.
static bool AddSplitImageFromChunkList(const ZipModeImage& tgt_image,
const ZipModeImage& src_image,
const SortedRangeSet& split_src_ranges,
const std::vector<ImageChunk>& split_tgt_chunks,
const std::vector<ImageChunk>& split_src_chunks,
std::vector<ZipModeImage>* split_tgt_images,
std::vector<ZipModeImage>* split_src_images);
// Function that actually iterates the tgt_chunks and makes patches.
static bool GeneratePatchesInternal(const ZipModeImage& tgt_image, const ZipModeImage& src_image,
std::vector<PatchChunk>* patch_chunks);
// size limit in bytes of each chunk. Also, if the length of one zip_entry exceeds the limit,
// we'll split that entry into several smaller chunks in advance.
size_t limit_;
class ImageModeImage : public Image {
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);