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Implement a custom deflate sink function for bspatch

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This new sink function works as a wrapper of the old sink. It deflates
the available patch data on the fly. Therefore, we don't need to store
the full uncompressed patch data in memory.

Test: recovery_component_test && apply an incremental update on angler
Change-Id: I2274ec50a1607089abcc9d0954a2a748f28c3122
This commit is contained in:
Tianjie Xu 2017-05-17 22:41:55 -07:00
parent 9c1a114789
commit a897f95bd5
1 changed files with 86 additions and 58 deletions
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144
applypatch/imgpatch.cpp
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@ -26,12 +26,14 @@
#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 <android-base/memory.h>
#include <openssl/sha.h>
#include <zlib.h>
@ -43,6 +45,86 @@ 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);
std::unique_ptr<z_stream, decltype(&deflateEnd)> strm(new z_stream(), deflateEnd);
strm->zalloc = Z_NULL;
strm->zfree = Z_NULL;
strm->opaque = Z_NULL;
strm->avail_in = 0;
strm->next_in = nullptr;
int ret = deflateInit2(strm.get(), 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 = [&](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.get(), Z_NO_FLUSH);
} else {
ret = deflate(strm.get(), 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;
};
if (ApplyBSDiffPatch(src_data, src_len, patch, patch_offset, compression_sink, nullptr) != 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));
@ -137,12 +219,6 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value*
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));
size_t target_len = static_cast<size_t>(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);
if (src_start + src_len > old_size) {
printf("source data too short\n");
@ -199,60 +275,12 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value*
}
}
// Next, apply the bsdiff patch (in memory) to the uncompressed data.
std::vector<uint8_t> uncompressed_target_data;
// TODO: replace the custom sink function passed into ApplyBSDiffPatch so that it wraps the
// given sink function to stream output to save memory.
if (ApplyBSDiffPatch(expanded_source.data(), expanded_len, patch, patch_offset,
[&uncompressed_target_data](const uint8_t* data, size_t len) {
uncompressed_target_data.insert(uncompressed_target_data.end(), data, data + len);
return len;
}, nullptr) != 0) {
return -1;
}
if (uncompressed_target_data.size() != target_len) {
printf("expected target len to be %zu, but it's %zu\n", target_len,
uncompressed_target_data.size());
if (!ApplyBSDiffPatchAndStreamOutput(expanded_source.data(), expanded_len, patch,
patch_offset, deflate_header, sink, ctx)) {
LOG(ERROR) << "Fail to apply streaming bspatch.";
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.
if (expanded_source.size() < 32768U) {
expanded_source.resize(32768U);
}
{
std::vector<unsigned char>& temp_data = expanded_source;
// now the deflate stream
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = uncompressed_target_data.size();
strm.next_in = uncompressed_target_data.data();
int ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
if (ret != Z_OK) {
printf("failed to init uncompressed data deflation: %d\n", ret);
return -1;
}
do {
strm.avail_out = temp_data.size();
strm.next_out = temp_data.data();
ret = deflate(&strm, Z_FINISH);
size_t have = temp_data.size() - strm.avail_out;
if (sink(temp_data.data(), have) != have) {
printf("failed to write %zd compressed bytes to output\n", have);
return -1;
}
if (ctx) SHA1_Update(ctx, temp_data.data(), have);
} while (ret != Z_STREAM_END);
deflateEnd(&strm);
}
} else {
printf("patch chunk %d is unknown type %d\n", i, type);
return -1;