src/zip_archive.cc - platform/art - Gitiles

 /*
  * 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 <vector>

 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>

 #include "UniquePtr.h"

 namespace art {

 static const size_t kBufSize = 32 * KB;

 // 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) {
   std::vector<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[0], bytes_to_read));
     if (actual != static_cast<ssize_t>(bytes_to_read)) {
       PLOG(WARNING) << "Zip: short read writing to file " << file.name();
       return false;
     }
     if (!file.WriteFully(&buf[0], bytes_to_read)) {
       PLOG(WARNING) << "Zip: failed to write to file " << file.name();
       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) {
   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) {
     LOG(WARNING) << "Zip: failed to alloctate buffer to inflate to file " << out.name();
     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)) {
         PLOG(WARNING) << "Zip: failed to write to file " << out.name();
         return false;
       }
       zstream->Get().next_out = write_buf.get();
       zstream->Get().avail_out = kBufSize;
     }
   } while (zerr == Z_OK);

   DCHECK_EQ(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) {
     LOG(WARNING) << "Zip: data_offset=" << data_offset;
     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:
       LOG(WARNING) << "Zip: unknown compression method " << std::hex << GetCompressionMethod();
       return false;
   }
 }

 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;
   }
   return Open(fd);
 }

 ZipArchive* ZipArchive::Open(int fd) {
   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
	/*
	* 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 <vector>

	#include <fcntl.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <unistd.h>

	#include "UniquePtr.h"

	namespace art {

	static const size_t kBufSize = 32 * KB;

	// 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) {
	std::vector<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[0], bytes_to_read));
	if (actual != static_cast<ssize_t>(bytes_to_read)) {
	PLOG(WARNING) << "Zip: short read writing to file " << file.name();
	return false;
	}
	if (!file.WriteFully(&buf[0], bytes_to_read)) {
	PLOG(WARNING) << "Zip: failed to write to file " << file.name();
	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) {
	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) {
	LOG(WARNING) << "Zip: failed to alloctate buffer to inflate to file " << out.name();
	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)) {
	PLOG(WARNING) << "Zip: failed to write to file " << out.name();
	return false;
	}
	zstream->Get().next_out = write_buf.get();
	zstream->Get().avail_out = kBufSize;
	}
	} while (zerr == Z_OK);

	DCHECK_EQ(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) {
	LOG(WARNING) << "Zip: data_offset=" << data_offset;
	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:
	LOG(WARNING) << "Zip: unknown compression method " << std::hex << GetCompressionMethod();
	return false;
	}
	}

	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;
	}
	return Open(fd);
	}

	ZipArchive* ZipArchive::Open(int fd) {
	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