diff options
Diffstat (limited to 'applypatch/imgdiff.cpp')
| -rw-r--r-- | applypatch/imgdiff.cpp | 189 |
1 files changed, 129 insertions, 60 deletions
diff --git a/applypatch/imgdiff.cpp b/applypatch/imgdiff.cpp index 2eb618fbf..c887a854d 100644 --- a/applypatch/imgdiff.cpp +++ b/applypatch/imgdiff.cpp @@ -15,53 +15,44 @@ */ /* - * 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. + * 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 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. + * 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. + * 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. + * For a diff to be generated, the source and target must be in well-formed zip archive format; + * or they are image files with 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.) + * 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] + * "IMGDIFF2" (8) [magic number and version] * chunk count (4) * for each chunk: * chunk type (4) [CHUNK_{NORMAL, GZIP, DEFLATE, RAW}] @@ -98,27 +89,55 @@ * 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). + * 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. + * 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 + * 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. + * + * When generating the patch between two zip files, this tool has an option "--block-limit" to + * split the large source/target files into several pair of pieces, with each piece has at most + * *limit* blocks. When this option is used, we also need to output the split info into the file + * path specified by "--split-info". + * + * Format of split info file: + * 2 [version of imgdiff] + * n [count of split pieces] + * <patch_size>, <tgt_size>, <src_range> [size and ranges for split piece#1] + * ... + * <patch_size>, <tgt_size>, <src_range> [size and ranges for split piece#n] + * + * To split a pair of large zip files, we walk through the chunks in target zip and search by its + * entry_name in the source zip. If the entry_name is non-empty and a matching entry in source + * is found, we'll add the source entry to the current split source image; otherwise we'll skip + * this chunk and later do bsdiff between all the skipped trunks and the whole split source image. + * We move on to the next pair of pieces if the size of the split source image reaches the block + * limit. + * + * After the split, the target pieces are continuous and block aligned, while the source pieces + * are mutually exclusive. Some of the source blocks may not be used if there's no matching + * entry_name in the target; as a result, they won't be included in any of these split source + * images. Then we will generate patches accordingly between each split image pairs; in particular, + * the unmatched trunks in the split target will diff against the entire split source image. + * + * For example: + * Input: [src_image, tgt_image] + * Split: [src-0, tgt-0; src-1, tgt-1, src-2, tgt-2] + * Diff: [ patch-0; patch-1; patch-2] + * + * Patch: [(src-0, patch-0) = tgt-0; (src-1, patch-1) = tgt-1; (src-2, patch-2) = tgt-2] + * Concatenate: [tgt-0 + tgt-1 + tgt-2 = tgt_image] */ #include "applypatch/imgdiff.h" @@ -151,6 +170,11 @@ using android::base::get_unaligned; +static constexpr size_t VERSION = 2; + +// We assume the header "IMGDIFF#" is 8 bytes. +static_assert(VERSION <= 9, "VERSION occupies more than one byte."); + static constexpr size_t BLOCK_SIZE = 4096; static constexpr size_t BUFFER_SIZE = 0x8000; @@ -224,6 +248,7 @@ static const struct option OPTIONS[] = { { "bonus-file", required_argument, nullptr, 'b' }, { "block-limit", required_argument, nullptr, 0 }, { "debug-dir", required_argument, nullptr, 0 }, + { "split-info", required_argument, nullptr, 0 }, { nullptr, 0, nullptr, 0 }, }; @@ -497,6 +522,13 @@ size_t PatchChunk::WriteHeaderToFd(int fd, size_t offset) const { } } +size_t PatchChunk::PatchSize() const { + if (type_ == CHUNK_RAW) { + return GetHeaderSize(); + } + return GetHeaderSize() + data_.size(); +} + // 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 @@ -509,8 +541,8 @@ bool PatchChunk::WritePatchDataToFd(const std::vector<PatchChunk>& patch_chunks, 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)); + if (!android::base::WriteStringToFd("IMGDIFF" + std::to_string(VERSION), patch_fd)) { + printf("failed to write \"IMGDIFF%zu\": %s\n", VERSION, strerror(errno)); return false; } @@ -1107,7 +1139,9 @@ bool ZipModeImage::GeneratePatches(const ZipModeImage& tgt_image, const ZipModeI bool ZipModeImage::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& debug_dir) { + const std::string& patch_name, + const std::string& split_info_file, + const std::string& debug_dir) { printf("Construct patches for %zu split images...\n", split_tgt_images.size()); android::base::unique_fd patch_fd( @@ -1117,6 +1151,7 @@ bool ZipModeImage::GeneratePatches(const std::vector<ZipModeImage>& split_tgt_im return false; } + std::vector<std::string> split_info_list; for (size_t i = 0; i < split_tgt_images.size(); i++) { std::vector<PatchChunk> patch_chunks; if (!ZipModeImage::GeneratePatchesInternal(split_tgt_images[i], split_src_images[i], @@ -1125,14 +1160,23 @@ bool ZipModeImage::GeneratePatches(const std::vector<ZipModeImage>& split_tgt_im return false; } + size_t total_patch_size = 12; for (auto& p : patch_chunks) { p.UpdateSourceOffset(split_src_ranges[i]); + total_patch_size += p.PatchSize(); } if (!PatchChunk::WritePatchDataToFd(patch_chunks, patch_fd)) { return false; } + size_t split_tgt_size = split_tgt_images[i].chunks_.back().GetStartOffset() + + split_tgt_images[i].chunks_.back().GetRawDataLength() - + split_tgt_images[i].chunks_.front().GetStartOffset(); + std::string split_info = android::base::StringPrintf( + "%zu %zu %s", total_patch_size, split_tgt_size, split_src_ranges[i].ToString().c_str()); + split_info_list.push_back(split_info); + // Write the split source & patch into the debug directory. if (!debug_dir.empty()) { std::string src_name = android::base::StringPrintf("%s/src-%zu", debug_dir.c_str(), i); @@ -1161,6 +1205,21 @@ bool ZipModeImage::GeneratePatches(const std::vector<ZipModeImage>& split_tgt_im } } } + + // Store the split in the following format: + // Line 0: imgdiff version# + // Line 1: number of pieces + // Line 2: patch_size_1 tgt_size_1 src_range_1 + // ... + // Line n+1: patch_size_n tgt_size_n src_range_n + std::string split_info_string = android::base::StringPrintf( + "%zu\n%zu\n", VERSION, split_info_list.size()) + android::base::Join(split_info_list, '\n'); + if (!android::base::WriteStringToFile(split_info_string, split_info_file)) { + printf("failed to write split info to \"%s\": %s\n", split_info_file.c_str(), + strerror(errno)); + return false; + } + return true; } @@ -1396,6 +1455,7 @@ int imgdiff(int argc, const char** argv) { bool zip_mode = false; std::vector<uint8_t> bonus_data; size_t blocks_limit = 0; + std::string split_info_file; std::string debug_dir; int opt; @@ -1432,6 +1492,8 @@ int imgdiff(int argc, const char** argv) { if (name == "block-limit" && !android::base::ParseUint(optarg, &blocks_limit)) { printf("failed to parse size blocks_limit: %s\n", optarg); return 1; + } else if (name == "split-info") { + split_info_file = optarg; } else if (name == "debug-dir") { debug_dir = optarg; } @@ -1451,6 +1513,8 @@ int imgdiff(int argc, const char** argv) { " --block-limit, For large zips, split the src and tgt based on the block limit;\n" " and generate patches between each pair of pieces. Concatenate these\n" " patches together and output them into <patch-file>.\n" + " --split-info, Output the split information (patch_size, tgt_size, src_ranges);\n" + " zip mode with block-limit only.\n" " --debug_dir, Debug directory to put the split srcs and patches, zip mode only.\n"); return 2; } @@ -1476,6 +1540,11 @@ int imgdiff(int argc, const char** argv) { // Compute bsdiff patches for each chunk's data (the uncompressed data, in the case of // deflate chunks). if (blocks_limit > 0) { + if (split_info_file.empty()) { + printf("split-info path cannot be empty when generating patches with a block-limit.\n"); + return 1; + } + std::vector<ZipModeImage> split_tgt_images; std::vector<ZipModeImage> split_src_images; std::vector<SortedRangeSet> split_src_ranges; @@ -1483,7 +1552,7 @@ int imgdiff(int argc, const char** argv) { &split_src_images, &split_src_ranges); if (!ZipModeImage::GeneratePatches(split_tgt_images, split_src_images, split_src_ranges, - argv[optind + 2], debug_dir)) { + argv[optind + 2], split_info_file, debug_dir)) { return 1; } |