// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/utility/safe_browsing/mac/udif.h"
#include <CoreFoundation/CoreFoundation.h>
#include <bzlib.h>
#include <libkern/OSByteOrder.h>
#include <uuid/uuid.h>
#include <algorithm>
#include <array>
#include <memory>
#include <optional>
#include <utility>
#include "base/apple/foundation_util.h"
#include "base/apple/scoped_cftyperef.h"
#include "base/containers/buffer_iterator.h"
#include "base/containers/span.h"
#include "base/logging.h"
#include "base/memory/raw_ptr.h"
#include "base/notreached.h"
#include "base/numerics/ostream_operators.h"
#include "base/numerics/safe_math.h"
#include "base/strings/sys_string_conversions.h"
#include "chrome/utility/safe_browsing/mac/convert_big_endian.h"
#include "chrome/utility/safe_browsing/mac/read_stream.h"
#include "third_party/zlib/zlib.h"
namespace safe_browsing {
namespace dmg {
#pragma pack(push, 1)
// The following structures come from the analysis provided by Jonathan Levin
// at <http://newosxbook.com/DMG.html>.
//
// Note that all fields are stored in big endian.
struct UDIFChecksum {
uint32_t type;
uint32_t size;
std::array<uint32_t, 32> data;
};
static void ConvertBigEndian(UDIFChecksum* checksum) {
ConvertBigEndian(&checksum->type);
ConvertBigEndian(&checksum->size);
for (size_t i = 0; i < std::size(checksum->data); ++i) {
ConvertBigEndian(&checksum->data[i]);
}
}
// The trailer structure for a UDIF file.
struct UDIFResourceFile {
static const uint32_t kSignature = 'koly';
static const uint32_t kVersion = 4;
uint32_t signature;
uint32_t version;
uint32_t header_size; // Size of this structure.
uint32_t flags;
uint64_t running_data_fork_offset;
uint64_t data_fork_offset;
uint64_t data_fork_length;
uint64_t rsrc_fork_offset;
uint64_t rsrc_fork_length;
uint32_t segment_number;
uint32_t segment_count;
uuid_t segment_id;
UDIFChecksum data_checksum;
uint64_t plist_offset; // Offset and length of the blkx plist.
uint64_t plist_length;
uint8_t reserved1[64];
uint64_t code_signature_offset;
uint64_t code_signature_length;
uint8_t reserved2[40];
UDIFChecksum main_checksum;
uint32_t image_variant;
uint64_t sector_count;
uint32_t reserved3;
uint32_t reserved4;
uint32_t reserved5;
};
static void ConvertBigEndian(uuid_t* uuid) {
// UUID is never consulted, so do not swap.
}
static void ConvertBigEndian(UDIFResourceFile* file) {
ConvertBigEndian(&file->signature);
ConvertBigEndian(&file->version);
ConvertBigEndian(&file->flags);
ConvertBigEndian(&file->header_size);
ConvertBigEndian(&file->running_data_fork_offset);
ConvertBigEndian(&file->data_fork_offset);
ConvertBigEndian(&file->data_fork_length);
ConvertBigEndian(&file->rsrc_fork_offset);
ConvertBigEndian(&file->rsrc_fork_length);
ConvertBigEndian(&file->segment_number);
ConvertBigEndian(&file->segment_count);
ConvertBigEndian(&file->segment_id);
ConvertBigEndian(&file->data_checksum);
ConvertBigEndian(&file->plist_offset);
ConvertBigEndian(&file->plist_length);
ConvertBigEndian(&file->code_signature_offset);
ConvertBigEndian(&file->code_signature_length);
ConvertBigEndian(&file->main_checksum);
ConvertBigEndian(&file->image_variant);
ConvertBigEndian(&file->sector_count);
// Reserved fields are skipped.
}
struct UDIFBlockChunk {
enum class Type : uint32_t {
ZERO_FILL = 0x00000000,
UNCOMPRESSED = 0x00000001,
IGNORED = 0x00000002,
COMPRESS_ADC = 0x80000004,
COMPRESS_ZLIB = 0x80000005,
COMPRESSS_BZ2 = 0x80000006,
COMMENT = 0x7ffffffe,
LAST_BLOCK = 0xffffffff,
};
Type type;
uint32_t comment;
uint64_t start_sector; // Logical chunk offset and length, in sectors.
uint64_t sector_count;
uint64_t compressed_offset; // Compressed offset and length, in bytes.
uint64_t compressed_length;
};
static void ConvertBigEndian(UDIFBlockChunk* chunk) {
ConvertBigEndian(reinterpret_cast<uint32_t*>(&chunk->type));
ConvertBigEndian(&chunk->comment);
ConvertBigEndian(&chunk->start_sector);
ConvertBigEndian(&chunk->sector_count);
ConvertBigEndian(&chunk->compressed_offset);
ConvertBigEndian(&chunk->compressed_length);
}
struct UDIFBlockData {
static const uint32_t kSignature = 'mish';
static const uint32_t kVersion = 1;
uint32_t signature;
uint32_t version;
uint64_t start_sector; // Logical block offset and length, in sectors.
uint64_t sector_count;
uint64_t data_offset;
uint32_t buffers_needed;
uint32_t block_descriptors;
uint32_t reserved1;
uint32_t reserved2;
uint32_t reserved3;
uint32_t reserved4;
uint32_t reserved5;
uint32_t reserved6;
UDIFChecksum checksum;
uint32_t chunk_count;
};
static void ConvertBigEndian(UDIFBlockData* block) {
ConvertBigEndian(&block->signature);
ConvertBigEndian(&block->version);
ConvertBigEndian(&block->start_sector);
ConvertBigEndian(&block->sector_count);
ConvertBigEndian(&block->data_offset);
ConvertBigEndian(&block->buffers_needed);
ConvertBigEndian(&block->block_descriptors);
// Reserved fields are skipped.
ConvertBigEndian(&block->checksum);
ConvertBigEndian(&block->chunk_count);
}
// UDIFBlock takes a raw, big-endian block data pointer and stores, in host
// endian, the data for both the block and the chunk.
class UDIFBlock {
public:
UDIFBlock() : block_() {}
UDIFBlock(const UDIFBlock&) = delete;
UDIFBlock& operator=(const UDIFBlock&) = delete;
bool ParseBlockData(base::span<const uint8_t> block_data,
uint16_t sector_size) {
base::BufferIterator iterator(block_data);
const UDIFBlockData* block_header = iterator.Object<UDIFBlockData>();
if (!block_header) {
DLOG(ERROR) << "UDIF block data is smaller than expected";
return false;
}
block_ = *block_header;
ConvertBigEndian(&block_);
// Make sure the number of sectors doesn't overflow.
auto block_size = base::CheckedNumeric<size_t>(sector_count()) *
sector_size;
if (!block_size.IsValid()) {
DLOG(ERROR) << "UDIF block size overflows";
return false;
}
// Make sure the block data contains the reported number of chunks.
auto block_and_chunks_size =
(base::CheckedNumeric<size_t>(sizeof(UDIFBlockChunk)) *
block_.chunk_count) +
sizeof(block_);
if (!block_and_chunks_size.IsValid() ||
block_data.size() < block_and_chunks_size.ValueOrDie()) {
DLOG(ERROR) << "UDIF block does not contain reported number of chunks, "
<< block_and_chunks_size.ValueOrDie() << " bytes expected, "
<< "got " << block_data.size();
return false;
}
// Make sure that the chunk data isn't larger than the block reports.
base::CheckedNumeric<size_t> chunk_sectors(0);
for (uint32_t i = 0; i < block_.chunk_count; ++i) {
const UDIFBlockChunk* raw_chunk = iterator.Object<UDIFBlockChunk>();
// Total size check above should ensure that the chunk always exists
CHECK(raw_chunk);
chunks_.push_back(*raw_chunk);
UDIFBlockChunk* chunk = &chunks_[i];
ConvertBigEndian(chunk);
chunk_sectors += chunk->sector_count;
if (!chunk_sectors.IsValid() ||
chunk_sectors.ValueOrDie() > sector_count()) {
DLOG(ERROR) << "Total chunk sectors larger than reported block sectors";
return false;
}
auto chunk_end_offset =
base::CheckedNumeric<size_t>(chunk->compressed_offset) +
chunk->compressed_length;
if (!chunk_end_offset.IsValid() ||
chunk->compressed_length > block_size.ValueOrDie()) {
DLOG(ERROR) << "UDIF chunk data length " << i << " overflows";
return false;
}
}
return true;
}
uint32_t signature() const { return block_.signature; }
uint32_t version() const { return block_.version; }
uint64_t start_sector() const { return block_.start_sector; }
uint64_t sector_count() const { return block_.sector_count; }
uint64_t chunk_count() const { return chunks_.size(); }
const UDIFBlockChunk* chunk(uint32_t i) const {
if (i >= chunk_count())
return nullptr;
return &chunks_[i];
}
private:
UDIFBlockData block_;
std::vector<UDIFBlockChunk> chunks_;
};
#pragma pack(pop)
namespace {
const size_t kSectorSize = 512;
class UDIFBlockChunkReadStream;
// A UDIFPartitionReadStream virtualizes a partition's non-contiguous blocks
// into a single stream.
class UDIFPartitionReadStream : public ReadStream {
public:
UDIFPartitionReadStream(ReadStream* stream,
uint16_t block_size,
const UDIFBlock* partition_block);
UDIFPartitionReadStream(const UDIFPartitionReadStream&) = delete;
UDIFPartitionReadStream& operator=(const UDIFPartitionReadStream&) = delete;
~UDIFPartitionReadStream() override;
bool Read(base::span<uint8_t> buf, size_t* bytes_read) override;
// Seek only supports SEEK_SET and SEEK_CUR.
off_t Seek(off_t offset, int whence) override;
private:
const raw_ptr<ReadStream> stream_; // The UDIF stream.
const uint16_t block_size_; // The UDIF block size.
const raw_ptr<const UDIFBlock> block_; // The block for this partition.
uint64_t current_chunk_; // The current chunk number.
// The current chunk stream.
std::unique_ptr<UDIFBlockChunkReadStream> chunk_stream_;
};
// A ReadStream for a single block chunk, which transparently handles
// decompression.
class UDIFBlockChunkReadStream : public ReadStream {
public:
UDIFBlockChunkReadStream(ReadStream* stream,
uint16_t block_size,
const UDIFBlockChunk* chunk);
UDIFBlockChunkReadStream(const UDIFBlockChunkReadStream&) = delete;
UDIFBlockChunkReadStream& operator=(const UDIFBlockChunkReadStream&) = delete;
~UDIFBlockChunkReadStream() override;
bool Read(base::span<uint8_t> buf, size_t* bytes_read) override;
// Seek only supports SEEK_SET.
off_t Seek(off_t offset, int whence) override;
bool IsAtEnd() { return offset_ >= length_in_bytes_; }
const UDIFBlockChunk* chunk() const { return chunk_; }
size_t length_in_bytes() const { return length_in_bytes_; }
private:
bool CopyOutZeros(base::span<uint8_t> buf, size_t* bytes_read);
bool CopyOutUncompressed(base::span<uint8_t> buf, size_t* bytes_read);
bool CopyOutDecompressed(base::span<uint8_t> buf, size_t* bytes_read);
bool HandleADC(base::span<uint8_t> buf, size_t* bytes_read);
bool HandleZLib(base::span<uint8_t> buf, size_t* bytes_read);
bool HandleBZ2(base::span<uint8_t> buf, size_t* bytes_read);
// Reads from |stream_| |chunk_->compressed_length| bytes, starting at
// |chunk_->compressed_offset|. Returns (possibly empty) vector containing
// data, or nullopt on error.
std::optional<std::vector<uint8_t>> ReadCompressedData();
const raw_ptr<ReadStream> stream_; // The UDIF stream.
const raw_ptr<const UDIFBlockChunk> chunk_; // The chunk to be read.
size_t length_in_bytes_; // The decompressed length in bytes.
size_t offset_; // The offset into the decompressed buffer.
std::vector<uint8_t> decompress_buffer_; // Decompressed data buffer.
bool did_decompress_; // Whether or not the chunk has been decompressed.
};
} // namespace
UDIFParser::UDIFParser(ReadStream* stream)
: stream_(stream),
partition_names_(),
blocks_(),
block_size_(kSectorSize) {}
UDIFParser::~UDIFParser() {}
bool UDIFParser::Parse() {
if (!ParseBlkx())
return false;
return true;
}
const std::vector<uint8_t>& UDIFParser::GetCodeSignature() {
return signature_blob_;
}
size_t UDIFParser::GetNumberOfPartitions() {
return blocks_.size();
}
std::string UDIFParser::GetPartitionName(size_t part_number) {
DCHECK_LT(part_number, partition_names_.size());
return partition_names_[part_number];
}
std::string UDIFParser::GetPartitionType(size_t part_number) {
// The partition type is embedded in the Name field, as such:
// "Partition-Name (Partition-Type : Partition-ID)".
std::string name = GetPartitionName(part_number);
size_t open = name.rfind('(');
size_t separator = name.rfind(':');
if (open == std::string::npos || separator == std::string::npos)
return std::string();
// Name does not end in ')' or no space after ':'.
if (*(name.end() - 1) != ')' ||
(name.size() - separator < 2 || name[separator + 1] != ' ')) {
return std::string();
}
--separator;
++open;
if (separator <= open)
return std::string();
return name.substr(open, separator - open);
}
size_t UDIFParser::GetPartitionSize(size_t part_number) {
DCHECK_LT(part_number, blocks_.size());
auto size =
base::CheckedNumeric<size_t>(blocks_[part_number]->sector_count()) *
block_size_;
return size.ValueOrDie();
}
std::unique_ptr<ReadStream> UDIFParser::GetPartitionReadStream(
size_t part_number) {
DCHECK_LT(part_number, blocks_.size());
return std::make_unique<UDIFPartitionReadStream>(stream_, block_size_,
blocks_[part_number].get());
}
bool UDIFParser::ParseBlkx() {
UDIFResourceFile trailer;
off_t trailer_start = stream_->Seek(-sizeof(trailer), SEEK_END);
if (trailer_start == -1)
return false;
if (!stream_->ReadType(trailer)) {
DLOG(ERROR) << "Failed to read UDIFResourceFile";
return false;
}
ConvertBigEndian(&trailer);
if (trailer.signature != trailer.kSignature) {
DLOG(ERROR) << "blkx signature does not match, is 0x"
<< std::hex << trailer.signature;
return false;
}
if (trailer.version != trailer.kVersion) {
DLOG(ERROR) << "blkx version does not match, is " << trailer.version;
return false;
}
auto plist_end = base::CheckedNumeric<size_t>(trailer.plist_offset) +
trailer.plist_length;
if (!plist_end.IsValid() ||
plist_end.ValueOrDie() > base::checked_cast<size_t>(trailer_start)) {
DLOG(ERROR) << "blkx plist extends past UDIF trailer";
return false;
}
std::vector<uint8_t> plist_bytes(trailer.plist_length, 0);
if (stream_->Seek(trailer.plist_offset, SEEK_SET) == -1)
return false;
if (trailer.plist_length == 0 || !stream_->ReadExact(plist_bytes)) {
DLOG(ERROR) << "Failed to read blkx plist data";
return false;
}
base::apple::ScopedCFTypeRef<CFDataRef> plist_data(
CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, plist_bytes.data(),
plist_bytes.size(), kCFAllocatorNull));
if (!plist_data) {
DLOG(ERROR) << "Failed to create data from bytes";
return false;
}
CFErrorRef error = nullptr;
base::apple::ScopedCFTypeRef<CFPropertyListRef> plist(
CFPropertyListCreateWithData(kCFAllocatorDefault, plist_data.get(),
kCFPropertyListImmutable, nullptr, &error));
CFDictionaryRef plist_dict =
base::apple::CFCast<CFDictionaryRef>(plist.get());
base::apple::ScopedCFTypeRef<CFErrorRef> error_ref(error);
if (error) {
base::apple::ScopedCFTypeRef<CFStringRef> error_string(
CFErrorCopyDescription(error));
DLOG(ERROR) << "Failed to parse XML plist: "
<< base::SysCFStringRefToUTF8(error_string.get());
return false;
}
if (!plist_dict) {
DLOG(ERROR) << "Plist is not a dictionary";
return false;
}
auto* resource_fork = base::apple::GetValueFromDictionary<CFDictionaryRef>(
plist_dict, CFSTR("resource-fork"));
if (!resource_fork) {
DLOG(ERROR) << "No resource-fork entry in plist";
return false;
}
auto* blkx = base::apple::GetValueFromDictionary<CFArrayRef>(resource_fork,
CFSTR("blkx"));
if (!blkx) {
DLOG(ERROR) << "No blkx entry in resource-fork";
return false;
}
for (CFIndex i = 0; i < CFArrayGetCount(blkx); ++i) {
auto* block_dictionary =
base::apple::CFCast<CFDictionaryRef>(CFArrayGetValueAtIndex(blkx, i));
if (!block_dictionary) {
DLOG(ERROR) << "Skipping block " << i
<< " because it is not a CFDictionary";
continue;
}
auto* data = base::apple::GetValueFromDictionary<CFDataRef>(
block_dictionary, CFSTR("Data"));
if (!data) {
DLOG(ERROR) << "Skipping block " << i
<< " because it has no Data section";
continue;
}
// Copy the block table out of the plist.
auto block = std::make_unique<UDIFBlock>();
// SAFETY: CFDataGetBytePtr is provided by Apple and documented to
// return CFDataGetLength bytes.
if (!block->ParseBlockData(UNSAFE_BUFFERS(
base::span(CFDataGetBytePtr(data),
base::checked_cast<size_t>(CFDataGetLength(data))),
block_size_))) {
DLOG(ERROR) << "Failed to parse UDIF block data";
return false;
}
if (block->signature() != UDIFBlockData::kSignature) {
DLOG(ERROR) << "Skipping block " << i << " because its signature does not"
<< " match, is 0x" << std::hex << block->signature();
continue;
}
if (block->version() != UDIFBlockData::kVersion) {
DLOG(ERROR) << "Skipping block " << i << "because its version does not "
<< "match, is " << block->version();
continue;
}
CFStringRef partition_name_cf = base::apple::CFCast<CFStringRef>(
CFDictionaryGetValue(block_dictionary, CFSTR("Name")));
if (!partition_name_cf) {
DLOG(ERROR) << "Skipping block " << i << " because it has no name";
continue;
}
std::string partition_name = base::SysCFStringRefToUTF8(partition_name_cf);
if (DLOG_IS_ON(INFO) && VLOG_IS_ON(1)) {
DVLOG(1) << "Name: " << partition_name;
DVLOG(1) << "StartSector = " << block->start_sector()
<< ", SectorCount = " << block->sector_count()
<< ", ChunkCount = " << block->chunk_count();
for (uint32_t j = 0; j < block->chunk_count(); ++j) {
const UDIFBlockChunk* chunk = block->chunk(j);
DVLOG(1) << "Chunk#" << j
<< " type = " << std::hex << static_cast<uint32_t>(chunk->type)
<< ", StartSector = " << std::dec << chunk->start_sector
<< ", SectorCount = " << chunk->sector_count
<< ", CompressOffset = " << chunk->compressed_offset
<< ", CompressLen = " << chunk->compressed_length;
}
}
blocks_.push_back(std::move(block));
partition_names_.push_back(partition_name);
}
// The offsets in the trailer could be garbage in DMGs that aren't signed.
// Need a sanity check that the DMG has legit values for these fields.
if (trailer.code_signature_length != 0 && trailer_start > 0) {
auto code_signature_end =
base::CheckedNumeric<size_t>(trailer.code_signature_offset) +
trailer.code_signature_length;
if (code_signature_end.IsValid() &&
code_signature_end.ValueOrDie() <=
base::checked_cast<size_t>(trailer_start)) {
signature_blob_.resize(trailer.code_signature_length);
off_t code_signature_start =
stream_->Seek(trailer.code_signature_offset, SEEK_SET);
if (code_signature_start == -1)
return false;
size_t bytes_read = 0;
if (!stream_->Read(signature_blob_, &bytes_read)) {
DLOG(ERROR) << "Failed to read raw signature bytes";
return false;
}
if (bytes_read != trailer.code_signature_length) {
DLOG(ERROR) << "Read unexpected number of raw signature bytes";
return false;
}
}
}
return true;
}
namespace {
UDIFPartitionReadStream::UDIFPartitionReadStream(
ReadStream* stream,
uint16_t block_size,
const UDIFBlock* partition_block)
: stream_(stream),
block_size_(block_size),
block_(partition_block),
current_chunk_(0),
chunk_stream_() {
}
UDIFPartitionReadStream::~UDIFPartitionReadStream() {}
bool UDIFPartitionReadStream::Read(base::span<uint8_t> buf,
size_t* bytes_read) {
size_t buffer_space_remaining = buf.size();
*bytes_read = 0;
for (uint32_t i = current_chunk_; i < block_->chunk_count(); ++i) {
const UDIFBlockChunk* chunk = block_->chunk(i);
// If this is the last block chunk, then the read is complete.
if (chunk->type == UDIFBlockChunk::Type::LAST_BLOCK) {
break;
}
// If the buffer is full, then the read is complete.
if (buffer_space_remaining == 0)
break;
// A chunk stream may exist if the last read from this chunk was partial,
// or if the stream was Seek()ed.
if (!chunk_stream_) {
chunk_stream_ = std::make_unique<UDIFBlockChunkReadStream>(
stream_, block_size_, chunk);
}
DCHECK_EQ(chunk, chunk_stream_->chunk());
size_t chunk_bytes_read = 0;
if (!chunk_stream_->Read(buf.last(buffer_space_remaining),
&chunk_bytes_read)) {
DLOG(ERROR) << "Failed to read " << buffer_space_remaining << " bytes "
<< "from chunk " << i;
return false;
}
*bytes_read += chunk_bytes_read;
buffer_space_remaining -= chunk_bytes_read;
if (chunk_stream_->IsAtEnd()) {
chunk_stream_.reset();
++current_chunk_;
}
}
return true;
}
off_t UDIFPartitionReadStream::Seek(off_t offset, int whence) {
// Translate SEEK_END to SEEK_SET. SEEK_CUR is not currently supported.
if (whence == SEEK_END) {
base::CheckedNumeric<off_t> safe_offset(block_->sector_count());
safe_offset *= block_size_;
safe_offset += offset;
if (!safe_offset.IsValid()) {
DLOG(ERROR) << "Seek offset overflows";
return -1;
}
offset = safe_offset.ValueOrDie();
} else if (whence != SEEK_SET) {
DCHECK_EQ(SEEK_SET, whence);
}
uint64_t sector = offset / block_size_;
// Find the chunk for this sector.
uint32_t chunk_number = 0;
const UDIFBlockChunk* chunk = nullptr;
for (uint32_t i = 0; i < block_->chunk_count(); ++i) {
const UDIFBlockChunk* chunk_it = block_->chunk(i);
// This assumes that all the chunks are ordered by sector.
if (i != 0) {
DLOG_IF(ERROR,
chunk_it->start_sector < block_->chunk(i - 1)->start_sector)
<< "Chunks are not ordered by sector at chunk " << i
<< " , previous start_sector = "
<< block_->chunk(i - 1)->start_sector << ", current = "
<< chunk_it->start_sector;
}
if (sector >= chunk_it->start_sector) {
chunk = chunk_it;
chunk_number = i;
} else {
break;
}
}
if (!chunk) {
DLOG(ERROR) << "Failed to Seek to partition offset " << offset;
return -1;
}
// Compute the offset into the chunk.
uint64_t offset_in_sector = offset % block_size_;
uint64_t start_sector = sector - chunk->start_sector;
base::CheckedNumeric<uint64_t> decompress_read_offset(start_sector);
decompress_read_offset *= block_size_;
decompress_read_offset += offset_in_sector;
if (!decompress_read_offset.IsValid()) {
DLOG(ERROR) << "Partition decompress read offset overflows";
return -1;
}
if (!chunk_stream_ || chunk != chunk_stream_->chunk()) {
chunk_stream_ =
std::make_unique<UDIFBlockChunkReadStream>(stream_, block_size_, chunk);
}
current_chunk_ = chunk_number;
if (chunk_stream_->Seek(
base::ValueOrDieForType<off_t>(decompress_read_offset), SEEK_SET) ==
-1)
return -1;
return offset;
}
UDIFBlockChunkReadStream::UDIFBlockChunkReadStream(ReadStream* stream,
uint16_t block_size,
const UDIFBlockChunk* chunk)
: stream_(stream),
chunk_(chunk),
length_in_bytes_(chunk->sector_count * block_size),
offset_(0),
decompress_buffer_(),
did_decompress_(false) {
// Make sure the multiplication above did not overflow.
CHECK(length_in_bytes_ == 0 || length_in_bytes_ >= block_size);
}
UDIFBlockChunkReadStream::~UDIFBlockChunkReadStream() {
}
bool UDIFBlockChunkReadStream::Read(base::span<uint8_t> buf,
size_t* bytes_read) {
switch (chunk_->type) {
case UDIFBlockChunk::Type::ZERO_FILL:
case UDIFBlockChunk::Type::IGNORED:
return CopyOutZeros(buf, bytes_read);
case UDIFBlockChunk::Type::UNCOMPRESSED:
return CopyOutUncompressed(buf, bytes_read);
case UDIFBlockChunk::Type::COMPRESS_ADC:
return HandleADC(buf, bytes_read);
case UDIFBlockChunk::Type::COMPRESS_ZLIB:
return HandleZLib(buf, bytes_read);
case UDIFBlockChunk::Type::COMPRESSS_BZ2:
return HandleBZ2(buf, bytes_read);
case UDIFBlockChunk::Type::COMMENT:
NOTREACHED_IN_MIGRATION();
break;
case UDIFBlockChunk::Type::LAST_BLOCK:
*bytes_read = 0;
return true;
}
return false;
}
off_t UDIFBlockChunkReadStream::Seek(off_t offset, int whence) {
DCHECK_EQ(SEEK_SET, whence);
if (static_cast<uint64_t>(offset) >= length_in_bytes_)
return -1;
offset_ = offset;
return offset_;
}
bool UDIFBlockChunkReadStream::CopyOutZeros(base::span<uint8_t> buf,
size_t* bytes_read) {
*bytes_read = std::min(buf.size(), length_in_bytes_ - offset_);
bzero(buf.data(), *bytes_read);
offset_ += *bytes_read;
return true;
}
bool UDIFBlockChunkReadStream::CopyOutUncompressed(base::span<uint8_t> buf,
size_t* bytes_read) {
*bytes_read = std::min(buf.size(), length_in_bytes_ - offset_);
if (*bytes_read == 0) {
return true;
}
uint64_t offset = chunk_->compressed_offset + offset_;
if (stream_->Seek(offset, SEEK_SET) == -1) {
return false;
}
bool rv = stream_->Read(buf.first(*bytes_read), bytes_read);
if (rv) {
offset_ += *bytes_read;
} else {
DLOG(ERROR) << "Failed to read uncompressed chunk data";
}
return rv;
}
bool UDIFBlockChunkReadStream::CopyOutDecompressed(base::span<uint8_t> buf,
size_t* bytes_read) {
DCHECK(did_decompress_);
*bytes_read = std::min(buf.size(), decompress_buffer_.size() - offset_);
base::span<uint8_t> src_data =
base::span(decompress_buffer_).subspan(offset_, *bytes_read);
buf.copy_prefix_from(src_data);
offset_ += *bytes_read;
return true;
}
bool UDIFBlockChunkReadStream::HandleADC(base::span<uint8_t> buf,
size_t* bytes_read) {
// TODO(rsesek): Implement ADC handling.
NOTIMPLEMENTED();
return false;
}
bool UDIFBlockChunkReadStream::HandleZLib(base::span<uint8_t> buf,
size_t* bytes_read) {
if (!did_decompress_) {
auto compressed_data_or_error = ReadCompressedData();
if (!compressed_data_or_error.has_value()) {
return false;
}
std::vector<uint8_t>& compressed_data = compressed_data_or_error.value();
z_stream zlib = {};
if (inflateInit(&zlib) != Z_OK) {
DLOG(ERROR) << "Failed to initialize zlib";
return false;
}
decompress_buffer_.resize(length_in_bytes_);
zlib.next_in = compressed_data.data();
zlib.avail_in = compressed_data.size();
zlib.next_out = decompress_buffer_.data();
zlib.avail_out = decompress_buffer_.size();
int rv = inflate(&zlib, Z_FINISH);
inflateEnd(&zlib);
if (rv != Z_STREAM_END) {
DLOG(ERROR) << "Failed to decompress zlib data, error = " << rv;
return false;
}
did_decompress_ = true;
}
return CopyOutDecompressed(buf, bytes_read);
}
bool UDIFBlockChunkReadStream::HandleBZ2(base::span<uint8_t> buf,
size_t* bytes_read) {
if (!did_decompress_) {
auto compressed_data_or_error = ReadCompressedData();
if (!compressed_data_or_error.has_value()) {
return false;
}
std::vector<uint8_t>& compressed_data = compressed_data_or_error.value();
bz_stream bz = {};
if (BZ2_bzDecompressInit(&bz, 0, 0) != BZ_OK) {
DLOG(ERROR) << "Failed to initialize bzlib";
return false;
}
decompress_buffer_.resize(length_in_bytes_);
bz.next_in = reinterpret_cast<char*>(compressed_data.data());
bz.avail_in = compressed_data.size();
bz.next_out = reinterpret_cast<char*>(decompress_buffer_.data());
bz.avail_out = decompress_buffer_.size();
int rv = BZ2_bzDecompress(&bz);
BZ2_bzDecompressEnd(&bz);
if (rv != BZ_STREAM_END) {
DLOG(ERROR) << "Failed to decompress BZ2 data, error = " << rv;
return false;
}
did_decompress_ = true;
}
return CopyOutDecompressed(buf, bytes_read);
}
std::optional<std::vector<uint8_t>>
UDIFBlockChunkReadStream::ReadCompressedData() {
std::vector<uint8_t> data;
data.resize(chunk_->compressed_length);
if (stream_->Seek(chunk_->compressed_offset, SEEK_SET) == -1) {
return std::nullopt;
}
if (!stream_->ReadExact(data)) {
return std::nullopt;
}
return data;
}
} // namespace
} // namespace dmg
} // namespace safe_browsing
Codebase Browser
chromium