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/*
* Copyright (C) 2008 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.
*/
#include "zip_archive.h"
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "UniquePtr.h"
namespace art {
// Get 2 little-endian bytes.
static uint32_t Le16ToHost(const byte* src) {
return ((src[0] << 0) |
(src[1] << 8));
}
// Get 4 little-endian bytes.
static uint32_t Le32ToHost(const byte* src) {
return ((src[0] << 0) |
(src[1] << 8) |
(src[2] << 16) |
(src[3] << 24));
}
uint16_t ZipEntry::GetCompressionMethod() {
return Le16ToHost(ptr_ + ZipArchive::kCDEMethod);
}
uint32_t ZipEntry::GetCompressedLength() {
return Le32ToHost(ptr_ + ZipArchive::kCDECompLen);
}
uint32_t ZipEntry::GetUncompressedLength() {
return Le32ToHost(ptr_ + ZipArchive::kCDEUncompLen);
}
uint32_t ZipEntry::GetCrc32() {
return Le32ToHost(ptr_ + ZipArchive::kCDECRC);
}
off_t ZipEntry::GetDataOffset() {
// All we have is the offset to the Local File Header, which is
// variable size, so we have to read the contents of the struct to
// figure out where the actual data starts.
// We also need to make sure that the lengths are not so large that
// somebody trying to map the compressed or uncompressed data runs
// off the end of the mapped region.
off_t dir_offset = zip_archive_->dir_offset_;
int64_t lfh_offset = Le32ToHost(ptr_ + ZipArchive::kCDELocalOffset);
if (lfh_offset + ZipArchive::kLFHLen >= dir_offset) {
LOG(WARNING) << "Zip: bad LFH offset in zip";
return -1;
}
if (lseek(zip_archive_->fd_, lfh_offset, SEEK_SET) != lfh_offset) {
PLOG(WARNING) << "Zip: failed seeking to LFH at offset " << lfh_offset;
return -1;
}
uint8_t lfh_buf[ZipArchive::kLFHLen];
ssize_t actual = TEMP_FAILURE_RETRY(read(zip_archive_->fd_, lfh_buf, sizeof(lfh_buf)));
if (actual != sizeof(lfh_buf)) {
LOG(WARNING) << "Zip: failed reading LFH from offset " << lfh_offset;
return -1;
}
if (Le32ToHost(lfh_buf) != ZipArchive::kLFHSignature) {
LOG(WARNING) << "Zip: didn't find signature at start of LFH, offset " << lfh_offset;
return -1;
}
off_t data_offset = (lfh_offset + ZipArchive::kLFHLen
+ Le16ToHost(lfh_buf + ZipArchive::kLFHNameLen)
+ Le16ToHost(lfh_buf + ZipArchive::kLFHExtraLen));
if (data_offset >= dir_offset) {
LOG(WARNING) << "Zip: bad data offset " << data_offset << " in zip";
return -1;
}
// check lengths
if (static_cast<off_t>(data_offset + GetCompressedLength()) > dir_offset) {
LOG(WARNING) << "Zip: bad compressed length in zip "
<< "(" << data_offset << " + " << GetCompressedLength()
<< " > " << dir_offset << ")";
return -1;
}
if (GetCompressionMethod() == kCompressStored
&& static_cast<off_t>(data_offset + GetUncompressedLength()) > dir_offset) {
LOG(WARNING) << "Zip: bad uncompressed length in zip "
<< "(" << data_offset << " + " << GetUncompressedLength()
<< " > " << dir_offset << ")";
return -1;
}
return data_offset;
}
static bool CopyFdToFile(File& file, int in, size_t count) {
const size_t kBufSize = 32768;
uint8_t buf[kBufSize];
while (count != 0) {
size_t bytes_to_read = (count > kBufSize) ? kBufSize : count;
ssize_t actual = TEMP_FAILURE_RETRY(read(in, buf, bytes_to_read));
if (actual != static_cast<ssize_t>(bytes_to_read)) {
return false;
}
if (!file.WriteFully(buf, bytes_to_read)) {
return false;
}
count -= bytes_to_read;
}
return true;
}
class ZStream {
public:
ZStream(byte* write_buf, size_t write_buf_size) {
// Initialize the zlib stream struct.
memset(&zstream_, 0, sizeof(zstream_));
zstream_.zalloc = Z_NULL;
zstream_.zfree = Z_NULL;
zstream_.opaque = Z_NULL;
zstream_.next_in = NULL;
zstream_.avail_in = 0;
zstream_.next_out = reinterpret_cast<Bytef*>(write_buf);
zstream_.avail_out = write_buf_size;
zstream_.data_type = Z_UNKNOWN;
}
z_stream& Get() {
return zstream_;
}
~ZStream() {
inflateEnd(&zstream_);
}
private:
z_stream zstream_;
};
static bool InflateToFile(File& out, int in, size_t uncompressed_length, size_t compressed_length) {
const size_t kBufSize = 32768;
UniquePtr<uint8_t[]> read_buf(new uint8_t[kBufSize]);
UniquePtr<uint8_t[]> write_buf(new uint8_t[kBufSize]);
if (read_buf.get() == NULL || write_buf.get() == NULL) {
return false;
}
UniquePtr<ZStream> zstream(new ZStream(write_buf.get(), kBufSize));
// Use the undocumented "negative window bits" feature to tell zlib
// that there's no zlib header waiting for it.
int zerr = inflateInit2(&zstream->Get(), -MAX_WBITS);
if (zerr != Z_OK) {
if (zerr == Z_VERSION_ERROR) {
LOG(ERROR) << "Installed zlib is not compatible with linked version (" << ZLIB_VERSION << ")";
} else {
LOG(WARNING) << "Call to inflateInit2 failed (zerr=" << zerr << ")";
}
return false;
}
size_t remaining = compressed_length;
do {
// read as much as we can
if (zstream->Get().avail_in == 0) {
size_t bytes_to_read = (remaining > kBufSize) ? kBufSize : remaining;
ssize_t actual = TEMP_FAILURE_RETRY(read(in, read_buf.get(), bytes_to_read));
if (actual != static_cast<ssize_t>(bytes_to_read)) {
LOG(WARNING) << "Zip: inflate read failed (" << actual << " vs " << bytes_to_read << ")";
return false;
}
remaining -= bytes_to_read;
zstream->Get().next_in = read_buf.get();
zstream->Get().avail_in = bytes_to_read;
}
// uncompress the data
zerr = inflate(&zstream->Get(), Z_NO_FLUSH);
if (zerr != Z_OK && zerr != Z_STREAM_END) {
LOG(WARNING) << "Zip: inflate zerr=" << zerr
<< " (nIn=" << zstream->Get().next_in
<< " aIn=" << zstream->Get().avail_in
<< " nOut=" << zstream->Get().next_out
<< " aOut=" << zstream->Get().avail_out
<< ")";
return false;
}
// write when we're full or when we're done
if (zstream->Get().avail_out == 0 ||
(zerr == Z_STREAM_END && zstream->Get().avail_out != kBufSize)) {
size_t bytes_to_write = zstream->Get().next_out - write_buf.get();
if (!out.WriteFully(write_buf.get(), bytes_to_write)) {
return false;
}
zstream->Get().next_out = write_buf.get();
zstream->Get().avail_out = kBufSize;
}
} while (zerr == Z_OK);
DCHECK(zerr == Z_STREAM_END); // other errors should've been caught
// paranoia
if (zstream->Get().total_out != uncompressed_length) {
LOG(WARNING) << "Zip: size mismatch on inflated file ("
<< zstream->Get().total_out << " vs " << uncompressed_length << ")";
return false;
}
return true;
}
bool ZipEntry::Extract(File& file) {
off_t data_offset = GetDataOffset();
if (data_offset == -1) {
return false;
}
if (lseek(zip_archive_->fd_, data_offset, SEEK_SET) != data_offset) {
PLOG(WARNING) << "Zip: lseek to data at " << data_offset << " failed";
return false;
}
// TODO: this doesn't verify the data's CRC, but probably should (especially
// for uncompressed data).
switch (GetCompressionMethod()) {
case kCompressStored:
return CopyFdToFile(file, zip_archive_->fd_, GetUncompressedLength());
case kCompressDeflated:
return InflateToFile(file, zip_archive_->fd_, GetUncompressedLength(), GetCompressedLength());
default:
return false;
}
}
// return new ZipArchive instance on success, NULL on error.
ZipArchive* ZipArchive::Open(const std::string& filename) {
DCHECK(!filename.empty());
int fd = open(filename.c_str(), O_RDONLY | O_CLOEXEC, 0);
if (fd < 0) {
PLOG(WARNING) << "Unable to open '" << filename << "'";
return NULL;
}
UniquePtr<ZipArchive> zip_archive(new ZipArchive(fd));
if (zip_archive.get() == NULL) {
return NULL;
}
if (!zip_archive->MapCentralDirectory()) {
zip_archive->Close();
return NULL;
}
if (!zip_archive->Parse()) {
zip_archive->Close();
return NULL;
}
return zip_archive.release();
}
ZipEntry* ZipArchive::Find(const char* name) {
DCHECK(name != NULL);
DirEntries::const_iterator it = dir_entries_.find(name);
if (it == dir_entries_.end()) {
return NULL;
}
return new ZipEntry(this, (*it).second);
}
void ZipArchive::Close() {
if (fd_ != -1) {
close(fd_);
}
fd_ = -1;
num_entries_ = 0;
dir_offset_ = 0;
}
// Find the zip Central Directory and memory-map it.
//
// On success, returns true after populating fields from the EOCD area:
// num_entries_
// dir_offset_
// dir_map_
bool ZipArchive::MapCentralDirectory() {
/*
* Get and test file length.
*/
off_t file_length = lseek(fd_, 0, SEEK_END);
if (file_length < kEOCDLen) {
LOG(WARNING) << "Zip: length " << file_length << " is too small to be zip";
return false;
}
// Perform the traditional EOCD snipe hunt.
//
// We're searching for the End of Central Directory magic number,
// which appears at the start of the EOCD block. It's followed by
// 18 bytes of EOCD stuff and up to 64KB of archive comment. We
// need to read the last part of the file into a buffer, dig through
// it to find the magic number, parse some values out, and use those
// to determine the extent of the CD.
//
// We start by pulling in the last part of the file.
size_t read_amount = kMaxEOCDSearch;
if (file_length < off_t(read_amount)) {
read_amount = file_length;
}
UniquePtr<uint8_t[]> scan_buf(new uint8_t[read_amount]);
if (scan_buf.get() == NULL) {
return false;
}
off_t search_start = file_length - read_amount;
if (lseek(fd_, search_start, SEEK_SET) != search_start) {
LOG(WARNING) << "Zip: seek " << search_start << " failed: " << strerror(errno);
return false;
}
ssize_t actual = TEMP_FAILURE_RETRY(read(fd_, scan_buf.get(), read_amount));
if (actual == -1) {
LOG(WARNING) << "Zip: read " << read_amount << " failed: " << strerror(errno);
return false;
}
// Scan backward for the EOCD magic. In an archive without a trailing
// comment, we'll find it on the first try. (We may want to consider
// doing an initial minimal read; if we don't find it, retry with a
// second read as above.)
int i;
for (i = read_amount - kEOCDLen; i >= 0; i--) {
if (scan_buf.get()[i] == 0x50 && Le32ToHost(&(scan_buf.get())[i]) == kEOCDSignature) {
break;
}
}
if (i < 0) {
LOG(WARNING) << "Zip: EOCD not found, not a zip file";
return false;
}
off_t eocd_offset = search_start + i;
const byte* eocd_ptr = scan_buf.get() + i;
DCHECK(eocd_offset < file_length);
// Grab the CD offset and size, and the number of entries in the
// archive. Verify that they look reasonable.
uint16_t num_entries = Le16ToHost(eocd_ptr + kEOCDNumEntries);
uint32_t dir_size = Le32ToHost(eocd_ptr + kEOCDSize);
uint32_t dir_offset = Le32ToHost(eocd_ptr + kEOCDFileOffset);
if ((uint64_t) dir_offset + (uint64_t) dir_size > (uint64_t) eocd_offset) {
LOG(WARNING) << "Zip: bad offsets ("
<< "dir=" << dir_offset << ", "
<< "size=" << dir_size << ", "
<< "eocd=" << eocd_offset << ")";
return false;
}
if (num_entries == 0) {
LOG(WARNING) << "Zip: empty archive?";
return false;
}
// It all looks good. Create a mapping for the CD.
dir_map_.reset(MemMap::Map(dir_size, PROT_READ, MAP_SHARED, fd_, dir_offset));
if (dir_map_.get() == NULL) {
return false;
}
num_entries_ = num_entries;
dir_offset_ = dir_offset;
return true;
}
bool ZipArchive::Parse() {
const byte* cd_ptr = dir_map_->GetAddress();
size_t cd_length = dir_map_->GetLength();
// Walk through the central directory, adding entries to the hash
// table and verifying values.
const byte* ptr = cd_ptr;
for (int i = 0; i < num_entries_; i++) {
if (Le32ToHost(ptr) != kCDESignature) {
LOG(WARNING) << "Zip: missed a central dir sig (at " << i << ")";
return false;
}
if (ptr + kCDELen > cd_ptr + cd_length) {
LOG(WARNING) << "Zip: ran off the end (at " << i << ")";
return false;
}
int64_t local_hdr_offset = Le32ToHost(ptr + kCDELocalOffset);
if (local_hdr_offset >= dir_offset_) {
LOG(WARNING) << "Zip: bad LFH offset " << local_hdr_offset << " at entry " << i;
return false;
}
uint16_t filename_len = Le16ToHost(ptr + kCDENameLen);
uint16_t extra_len = Le16ToHost(ptr + kCDEExtraLen);
uint16_t comment_len = Le16ToHost(ptr + kCDECommentLen);
// add the CDE filename to the hash table
const char* name = reinterpret_cast<const char*>(ptr + kCDELen);
bool success = dir_entries_.insert(std::make_pair(StringPiece(name, filename_len), ptr)).second;
if (!success) {
return false;
}
ptr += kCDELen + filename_len + extra_len + comment_len;
if (ptr > cd_ptr + cd_length) {
LOG(WARNING) << "Zip: bad CD advance "
<< "(" << ptr << " vs " << (cd_ptr + cd_length) << ") "
<< "at entry " << i;
return false;
}
}
return true;
}
} // namespace art