replicant-frameworks_native/libs/utils/ZipFileRO.cpp
Kenny Root 61ef747e0e Use pread() in ZipFileRO for Linux
AssetManager instances are created by zygote and passed to all its
children so that they don't have to individually open
frameworks-res.apk. This creates a problem for determining the current
file offset when using lseek() on those files, because you can't
guarantee the cross-process locking of a mutex. Luckily, Linux
implements pread() to get around this suckiness.

The problem is that only Linux implements this, so we have to keep the
old locking for use on host builds with aapt and friends. aapt doesn't
have this same problem of sharing file descriptors across forked
processes, so we can keep the local AutoMutex to protect accesses of
those files.

Change-Id: Ibe9f11499a53fe345f50fbaea438815ec0fd363e
2010-10-04 15:17:19 -07:00

907 lines
27 KiB
C++

/*
* Copyright (C) 2007 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.
*/
//
// Read-only access to Zip archives, with minimal heap allocation.
//
#define LOG_TAG "zipro"
//#define LOG_NDEBUG 0
#include <utils/ZipFileRO.h>
#include <utils/Log.h>
#include <utils/misc.h>
#include <utils/threads.h>
#include <zlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
#include <unistd.h>
/*
* TEMP_FAILURE_RETRY is defined by some, but not all, versions of
* <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
* not already defined, then define it here.
*/
#ifndef TEMP_FAILURE_RETRY
/* Used to retry syscalls that can return EINTR. */
#define TEMP_FAILURE_RETRY(exp) ({ \
typeof (exp) _rc; \
do { \
_rc = (exp); \
} while (_rc == -1 && errno == EINTR); \
_rc; })
#endif
using namespace android;
/*
* Zip file constants.
*/
#define kEOCDSignature 0x06054b50
#define kEOCDLen 22
#define kEOCDNumEntries 8 // offset to #of entries in file
#define kEOCDSize 12 // size of the central directory
#define kEOCDFileOffset 16 // offset to central directory
#define kMaxCommentLen 65535 // longest possible in ushort
#define kMaxEOCDSearch (kMaxCommentLen + kEOCDLen)
#define kLFHSignature 0x04034b50
#define kLFHLen 30 // excluding variable-len fields
#define kLFHNameLen 26 // offset to filename length
#define kLFHExtraLen 28 // offset to extra length
#define kCDESignature 0x02014b50
#define kCDELen 46 // excluding variable-len fields
#define kCDEMethod 10 // offset to compression method
#define kCDEModWhen 12 // offset to modification timestamp
#define kCDECRC 16 // offset to entry CRC
#define kCDECompLen 20 // offset to compressed length
#define kCDEUncompLen 24 // offset to uncompressed length
#define kCDENameLen 28 // offset to filename length
#define kCDEExtraLen 30 // offset to extra length
#define kCDECommentLen 32 // offset to comment length
#define kCDELocalOffset 42 // offset to local hdr
/*
* The values we return for ZipEntryRO use 0 as an invalid value, so we
* want to adjust the hash table index by a fixed amount. Using a large
* value helps insure that people don't mix & match arguments, e.g. to
* findEntryByIndex().
*/
#define kZipEntryAdj 10000
ZipFileRO::~ZipFileRO() {
free(mHashTable);
if (mDirectoryMap)
mDirectoryMap->release();
if (mFd >= 0)
TEMP_FAILURE_RETRY(close(mFd));
if (mFileName)
free(mFileName);
}
/*
* Convert a ZipEntryRO to a hash table index, verifying that it's in a
* valid range.
*/
int ZipFileRO::entryToIndex(const ZipEntryRO entry) const
{
long ent = ((long) entry) - kZipEntryAdj;
if (ent < 0 || ent >= mHashTableSize || mHashTable[ent].name == NULL) {
LOGW("Invalid ZipEntryRO %p (%ld)\n", entry, ent);
return -1;
}
return ent;
}
/*
* Open the specified file read-only. We memory-map the entire thing and
* close the file before returning.
*/
status_t ZipFileRO::open(const char* zipFileName)
{
int fd = -1;
assert(mDirectoryMap == NULL);
/*
* Open and map the specified file.
*/
fd = ::open(zipFileName, O_RDONLY);
if (fd < 0) {
LOGW("Unable to open zip '%s': %s\n", zipFileName, strerror(errno));
return NAME_NOT_FOUND;
}
mFileLength = lseek(fd, 0, SEEK_END);
if (mFileLength < kEOCDLen) {
TEMP_FAILURE_RETRY(close(fd));
return UNKNOWN_ERROR;
}
if (mFileName != NULL) {
free(mFileName);
}
mFileName = strdup(zipFileName);
mFd = fd;
/*
* Find the Central Directory and store its size and number of entries.
*/
if (!mapCentralDirectory()) {
goto bail;
}
/*
* Verify Central Directory and create data structures for fast access.
*/
if (!parseZipArchive()) {
goto bail;
}
return OK;
bail:
free(mFileName);
mFileName = NULL;
TEMP_FAILURE_RETRY(close(fd));
return UNKNOWN_ERROR;
}
/*
* Parse the Zip archive, verifying its contents and initializing internal
* data structures.
*/
bool ZipFileRO::mapCentralDirectory(void)
{
size_t readAmount = kMaxEOCDSearch;
if (readAmount > (size_t) mFileLength)
readAmount = mFileLength;
unsigned char* scanBuf = (unsigned char*) malloc(readAmount);
if (scanBuf == NULL) {
LOGW("couldn't allocate scanBuf: %s", strerror(errno));
free(scanBuf);
return false;
}
/*
* Make sure this is a Zip archive.
*/
if (lseek(mFd, 0, SEEK_SET) != 0) {
LOGW("seek to start failed: %s", strerror(errno));
free(scanBuf);
return false;
}
ssize_t actual = TEMP_FAILURE_RETRY(read(mFd, scanBuf, sizeof(int32_t)));
if (actual != (ssize_t) sizeof(int32_t)) {
LOGI("couldn't read first signature from zip archive: %s", strerror(errno));
free(scanBuf);
return false;
}
{
unsigned int header = get4LE(scanBuf);
if (header == kEOCDSignature) {
LOGI("Found Zip archive, but it looks empty\n");
free(scanBuf);
return false;
} else if (header != kLFHSignature) {
LOGV("Not a Zip archive (found 0x%08x)\n", header);
free(scanBuf);
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.
*/
off_t searchStart = mFileLength - readAmount;
if (lseek(mFd, searchStart, SEEK_SET) != searchStart) {
LOGW("seek %ld failed: %s\n", (long) searchStart, strerror(errno));
free(scanBuf);
return false;
}
actual = TEMP_FAILURE_RETRY(read(mFd, scanBuf, readAmount));
if (actual != (ssize_t) readAmount) {
LOGW("Zip: read %zd failed: %s\n", readAmount, strerror(errno));
free(scanBuf);
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 = readAmount - kEOCDLen; i >= 0; i--) {
if (scanBuf[i] == 0x50 && get4LE(&scanBuf[i]) == kEOCDSignature) {
LOGV("+++ Found EOCD at buf+%d\n", i);
break;
}
}
if (i < 0) {
LOGD("Zip: EOCD not found, %s is not zip\n", mFileName);
free(scanBuf);
return false;
}
off_t eocdOffset = searchStart + i;
const unsigned char* eocdPtr = scanBuf + i;
assert(eocdOffset < mFileLength);
/*
* Grab the CD offset and size, and the number of entries in the
* archive. After that, we can release our EOCD hunt buffer.
*/
unsigned int numEntries = get2LE(eocdPtr + kEOCDNumEntries);
unsigned int dirSize = get4LE(eocdPtr + kEOCDSize);
unsigned int dirOffset = get4LE(eocdPtr + kEOCDFileOffset);
free(scanBuf);
// Verify that they look reasonable.
if ((long long) dirOffset + (long long) dirSize > (long long) eocdOffset) {
LOGW("bad offsets (dir %ld, size %u, eocd %ld)\n",
(long) dirOffset, dirSize, (long) eocdOffset);
return false;
}
if (numEntries == 0) {
LOGW("empty archive?\n");
return false;
}
LOGV("+++ numEntries=%d dirSize=%d dirOffset=%d\n",
numEntries, dirSize, dirOffset);
mDirectoryMap = new FileMap();
if (mDirectoryMap == NULL) {
LOGW("Unable to create directory map: %s", strerror(errno));
return false;
}
if (!mDirectoryMap->create(mFileName, mFd, dirOffset, dirSize, true)) {
LOGW("Unable to map '%s' (%zd to %zd): %s\n", mFileName,
dirOffset, dirOffset + dirSize, strerror(errno));
return false;
}
mNumEntries = numEntries;
mDirectoryOffset = dirOffset;
return true;
}
bool ZipFileRO::parseZipArchive(void)
{
bool result = false;
const unsigned char* cdPtr = (const unsigned char*) mDirectoryMap->getDataPtr();
size_t cdLength = mDirectoryMap->getDataLength();
int numEntries = mNumEntries;
/*
* Create hash table. We have a minimum 75% load factor, possibly as
* low as 50% after we round off to a power of 2.
*/
mHashTableSize = roundUpPower2(1 + (numEntries * 4) / 3);
mHashTable = (HashEntry*) calloc(mHashTableSize, sizeof(HashEntry));
/*
* Walk through the central directory, adding entries to the hash
* table.
*/
const unsigned char* ptr = cdPtr;
for (int i = 0; i < numEntries; i++) {
if (get4LE(ptr) != kCDESignature) {
LOGW("Missed a central dir sig (at %d)\n", i);
goto bail;
}
if (ptr + kCDELen > cdPtr + cdLength) {
LOGW("Ran off the end (at %d)\n", i);
goto bail;
}
long localHdrOffset = (long) get4LE(ptr + kCDELocalOffset);
if (localHdrOffset >= mDirectoryOffset) {
LOGW("bad LFH offset %ld at entry %d\n", localHdrOffset, i);
goto bail;
}
unsigned int fileNameLen, extraLen, commentLen, hash;
fileNameLen = get2LE(ptr + kCDENameLen);
extraLen = get2LE(ptr + kCDEExtraLen);
commentLen = get2LE(ptr + kCDECommentLen);
/* add the CDE filename to the hash table */
hash = computeHash((const char*)ptr + kCDELen, fileNameLen);
addToHash((const char*)ptr + kCDELen, fileNameLen, hash);
ptr += kCDELen + fileNameLen + extraLen + commentLen;
if ((size_t)(ptr - cdPtr) > cdLength) {
LOGW("bad CD advance (%d vs %zd) at entry %d\n",
(int) (ptr - cdPtr), cdLength, i);
goto bail;
}
}
LOGV("+++ zip good scan %d entries\n", numEntries);
result = true;
bail:
return result;
}
/*
* Simple string hash function for non-null-terminated strings.
*/
/*static*/ unsigned int ZipFileRO::computeHash(const char* str, int len)
{
unsigned int hash = 0;
while (len--)
hash = hash * 31 + *str++;
return hash;
}
/*
* Add a new entry to the hash table.
*/
void ZipFileRO::addToHash(const char* str, int strLen, unsigned int hash)
{
int ent = hash & (mHashTableSize-1);
/*
* We over-allocate the table, so we're guaranteed to find an empty slot.
*/
while (mHashTable[ent].name != NULL)
ent = (ent + 1) & (mHashTableSize-1);
mHashTable[ent].name = str;
mHashTable[ent].nameLen = strLen;
}
/*
* Find a matching entry.
*
* Returns 0 if not found.
*/
ZipEntryRO ZipFileRO::findEntryByName(const char* fileName) const
{
int nameLen = strlen(fileName);
unsigned int hash = computeHash(fileName, nameLen);
int ent = hash & (mHashTableSize-1);
while (mHashTable[ent].name != NULL) {
if (mHashTable[ent].nameLen == nameLen &&
memcmp(mHashTable[ent].name, fileName, nameLen) == 0)
{
/* match */
return (ZipEntryRO)(long)(ent + kZipEntryAdj);
}
ent = (ent + 1) & (mHashTableSize-1);
}
return NULL;
}
/*
* Find the Nth entry.
*
* This currently involves walking through the sparse hash table, counting
* non-empty entries. If we need to speed this up we can either allocate
* a parallel lookup table or (perhaps better) provide an iterator interface.
*/
ZipEntryRO ZipFileRO::findEntryByIndex(int idx) const
{
if (idx < 0 || idx >= mNumEntries) {
LOGW("Invalid index %d\n", idx);
return NULL;
}
for (int ent = 0; ent < mHashTableSize; ent++) {
if (mHashTable[ent].name != NULL) {
if (idx-- == 0)
return (ZipEntryRO) (ent + kZipEntryAdj);
}
}
return NULL;
}
/*
* Get the useful fields from the zip entry.
*
* Returns "false" if the offsets to the fields or the contents of the fields
* appear to be bogus.
*/
bool ZipFileRO::getEntryInfo(ZipEntryRO entry, int* pMethod, size_t* pUncompLen,
size_t* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) const
{
bool ret = false;
const int ent = entryToIndex(entry);
if (ent < 0)
return false;
HashEntry hashEntry = mHashTable[ent];
/*
* Recover the start of the central directory entry from the filename
* pointer. The filename is the first entry past the fixed-size data,
* so we can just subtract back from that.
*/
const unsigned char* ptr = (const unsigned char*) hashEntry.name;
off_t cdOffset = mDirectoryOffset;
ptr -= kCDELen;
int method = get2LE(ptr + kCDEMethod);
if (pMethod != NULL)
*pMethod = method;
if (pModWhen != NULL)
*pModWhen = get4LE(ptr + kCDEModWhen);
if (pCrc32 != NULL)
*pCrc32 = get4LE(ptr + kCDECRC);
size_t compLen = get4LE(ptr + kCDECompLen);
if (pCompLen != NULL)
*pCompLen = compLen;
size_t uncompLen = get4LE(ptr + kCDEUncompLen);
if (pUncompLen != NULL)
*pUncompLen = uncompLen;
/*
* If requested, determine the offset of the start of the data. 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.
*
* Note we don't verify compLen/uncompLen if they don't request the
* dataOffset, because dataOffset is expensive to determine. However,
* if they don't have the file offset, they're not likely to be doing
* anything with the contents.
*/
if (pOffset != NULL) {
long localHdrOffset = get4LE(ptr + kCDELocalOffset);
if (localHdrOffset + kLFHLen >= cdOffset) {
LOGE("ERROR: bad local hdr offset in zip\n");
return false;
}
unsigned char lfhBuf[kLFHLen];
#ifdef HAVE_PREAD
/*
* This file descriptor might be from zygote's preloaded assets,
* so we need to do an pread() instead of a lseek() + read() to
* guarantee atomicity across the processes with the shared file
* descriptors.
*/
ssize_t actual =
TEMP_FAILURE_RETRY(pread(mFd, lfhBuf, sizeof(lfhBuf), localHdrOffset));
if (actual != sizeof(lfhBuf)) {
LOGW("failed reading lfh from offset %ld\n", localHdrOffset);
return false;
}
if (get4LE(lfhBuf) != kLFHSignature) {
LOGW("didn't find signature at start of lfh; wanted: offset=%ld data=0x%08x; "
"got: data=0x%08lx\n",
localHdrOffset, kLFHSignature, get4LE(lfhBuf));
return false;
}
#else /* HAVE_PREAD */
/*
* For hosts don't have pread() we cannot guarantee atomic reads from
* an offset in a file. Android should never run on those platforms.
* File descriptors inherited from a fork() share file offsets and
* there would be nothing to protect from two different processes
* calling lseek() concurrently.
*/
{
AutoMutex _l(mFdLock);
if (lseek(mFd, localHdrOffset, SEEK_SET) != localHdrOffset) {
LOGW("failed seeking to lfh at offset %ld\n", localHdrOffset);
return false;
}
ssize_t actual =
TEMP_FAILURE_RETRY(read(mFd, lfhBuf, sizeof(lfhBuf)));
if (actual != sizeof(lfhBuf)) {
LOGW("failed reading lfh from offset %ld\n", localHdrOffset);
return false;
}
if (get4LE(lfhBuf) != kLFHSignature) {
off_t actualOffset = lseek(mFd, 0, SEEK_CUR);
LOGW("didn't find signature at start of lfh; wanted: offset=%ld data=0x%08x; "
"got: offset=%zd data=0x%08lx\n",
localHdrOffset, kLFHSignature, (size_t)actualOffset, get4LE(lfhBuf));
return false;
}
}
#endif /* HAVE_PREAD */
off_t dataOffset = localHdrOffset + kLFHLen
+ get2LE(lfhBuf + kLFHNameLen) + get2LE(lfhBuf + kLFHExtraLen);
if (dataOffset >= cdOffset) {
LOGW("bad data offset %ld in zip\n", (long) dataOffset);
return false;
}
/* check lengths */
if ((off_t)(dataOffset + compLen) > cdOffset) {
LOGW("bad compressed length in zip (%ld + %zd > %ld)\n",
(long) dataOffset, compLen, (long) cdOffset);
return false;
}
if (method == kCompressStored &&
(off_t)(dataOffset + uncompLen) > cdOffset)
{
LOGE("ERROR: bad uncompressed length in zip (%ld + %zd > %ld)\n",
(long) dataOffset, uncompLen, (long) cdOffset);
return false;
}
*pOffset = dataOffset;
}
return true;
}
/*
* Copy the entry's filename to the buffer.
*/
int ZipFileRO::getEntryFileName(ZipEntryRO entry, char* buffer, int bufLen)
const
{
int ent = entryToIndex(entry);
if (ent < 0)
return -1;
int nameLen = mHashTable[ent].nameLen;
if (bufLen < nameLen+1)
return nameLen+1;
memcpy(buffer, mHashTable[ent].name, nameLen);
buffer[nameLen] = '\0';
return 0;
}
/*
* Create a new FileMap object that spans the data in "entry".
*/
FileMap* ZipFileRO::createEntryFileMap(ZipEntryRO entry) const
{
/*
* TODO: the efficient way to do this is to modify FileMap to allow
* sub-regions of a file to be mapped. A reference-counting scheme
* can manage the base memory mapping. For now, we just create a brand
* new mapping off of the Zip archive file descriptor.
*/
FileMap* newMap;
size_t compLen;
off_t offset;
if (!getEntryInfo(entry, NULL, NULL, &compLen, &offset, NULL, NULL))
return NULL;
newMap = new FileMap();
if (!newMap->create(mFileName, mFd, offset, compLen, true)) {
newMap->release();
return NULL;
}
return newMap;
}
/*
* Uncompress an entry, in its entirety, into the provided output buffer.
*
* This doesn't verify the data's CRC, which might be useful for
* uncompressed data. The caller should be able to manage it.
*/
bool ZipFileRO::uncompressEntry(ZipEntryRO entry, void* buffer) const
{
const size_t kSequentialMin = 32768;
bool result = false;
int ent = entryToIndex(entry);
if (ent < 0)
return -1;
int method;
size_t uncompLen, compLen;
off_t offset;
const unsigned char* ptr;
getEntryInfo(entry, &method, &uncompLen, &compLen, &offset, NULL, NULL);
FileMap* file = createEntryFileMap(entry);
if (file == NULL) {
goto bail;
}
ptr = (const unsigned char*) file->getDataPtr();
/*
* Experiment with madvise hint. When we want to uncompress a file,
* we pull some stuff out of the central dir entry and then hit a
* bunch of compressed or uncompressed data sequentially. The CDE
* visit will cause a limited amount of read-ahead because it's at
* the end of the file. We could end up doing lots of extra disk
* access if the file we're prying open is small. Bottom line is we
* probably don't want to turn MADV_SEQUENTIAL on and leave it on.
*
* So, if the compressed size of the file is above a certain minimum
* size, temporarily boost the read-ahead in the hope that the extra
* pair of system calls are negated by a reduction in page faults.
*/
if (compLen > kSequentialMin)
file->advise(FileMap::SEQUENTIAL);
if (method == kCompressStored) {
memcpy(buffer, ptr, uncompLen);
} else {
if (!inflateBuffer(buffer, ptr, uncompLen, compLen))
goto unmap;
}
if (compLen > kSequentialMin)
file->advise(FileMap::NORMAL);
result = true;
unmap:
file->release();
bail:
return result;
}
/*
* Uncompress an entry, in its entirety, to an open file descriptor.
*
* This doesn't verify the data's CRC, but probably should.
*/
bool ZipFileRO::uncompressEntry(ZipEntryRO entry, int fd) const
{
bool result = false;
int ent = entryToIndex(entry);
if (ent < 0)
return -1;
int method;
size_t uncompLen, compLen;
off_t offset;
const unsigned char* ptr;
getEntryInfo(entry, &method, &uncompLen, &compLen, &offset, NULL, NULL);
FileMap* file = createEntryFileMap(entry);
if (file == NULL) {
goto bail;
}
ptr = (const unsigned char*) file->getDataPtr();
if (method == kCompressStored) {
ssize_t actual = write(fd, ptr, uncompLen);
if (actual < 0) {
LOGE("Write failed: %s\n", strerror(errno));
goto unmap;
} else if ((size_t) actual != uncompLen) {
LOGE("Partial write during uncompress (%zd of %zd)\n",
(size_t)actual, (size_t)uncompLen);
goto unmap;
} else {
LOGI("+++ successful write\n");
}
} else {
if (!inflateBuffer(fd, ptr, uncompLen, compLen))
goto unmap;
}
result = true;
unmap:
file->release();
bail:
return result;
}
/*
* Uncompress "deflate" data from one buffer to another.
*/
/*static*/ bool ZipFileRO::inflateBuffer(void* outBuf, const void* inBuf,
size_t uncompLen, size_t compLen)
{
bool result = false;
z_stream zstream;
int zerr;
/*
* 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 = (Bytef*)inBuf;
zstream.avail_in = compLen;
zstream.next_out = (Bytef*) outBuf;
zstream.avail_out = uncompLen;
zstream.data_type = Z_UNKNOWN;
/*
* Use the undocumented "negative window bits" feature to tell zlib
* that there's no zlib header waiting for it.
*/
zerr = inflateInit2(&zstream, -MAX_WBITS);
if (zerr != Z_OK) {
if (zerr == Z_VERSION_ERROR) {
LOGE("Installed zlib is not compatible with linked version (%s)\n",
ZLIB_VERSION);
} else {
LOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
}
goto bail;
}
/*
* Expand data.
*/
zerr = inflate(&zstream, Z_FINISH);
if (zerr != Z_STREAM_END) {
LOGW("Zip inflate failed, zerr=%d (nIn=%p aIn=%u nOut=%p aOut=%u)\n",
zerr, zstream.next_in, zstream.avail_in,
zstream.next_out, zstream.avail_out);
goto z_bail;
}
/* paranoia */
if (zstream.total_out != uncompLen) {
LOGW("Size mismatch on inflated file (%ld vs %zd)\n",
zstream.total_out, uncompLen);
goto z_bail;
}
result = true;
z_bail:
inflateEnd(&zstream); /* free up any allocated structures */
bail:
return result;
}
/*
* Uncompress "deflate" data from one buffer to an open file descriptor.
*/
/*static*/ bool ZipFileRO::inflateBuffer(int fd, const void* inBuf,
size_t uncompLen, size_t compLen)
{
bool result = false;
const size_t kWriteBufSize = 32768;
unsigned char writeBuf[kWriteBufSize];
z_stream zstream;
int zerr;
/*
* 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 = (Bytef*)inBuf;
zstream.avail_in = compLen;
zstream.next_out = (Bytef*) writeBuf;
zstream.avail_out = sizeof(writeBuf);
zstream.data_type = Z_UNKNOWN;
/*
* Use the undocumented "negative window bits" feature to tell zlib
* that there's no zlib header waiting for it.
*/
zerr = inflateInit2(&zstream, -MAX_WBITS);
if (zerr != Z_OK) {
if (zerr == Z_VERSION_ERROR) {
LOGE("Installed zlib is not compatible with linked version (%s)\n",
ZLIB_VERSION);
} else {
LOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
}
goto bail;
}
/*
* Loop while we have more to do.
*/
do {
/*
* Expand data.
*/
zerr = inflate(&zstream, Z_NO_FLUSH);
if (zerr != Z_OK && zerr != Z_STREAM_END) {
LOGW("zlib inflate: zerr=%d (nIn=%p aIn=%u nOut=%p aOut=%u)\n",
zerr, zstream.next_in, zstream.avail_in,
zstream.next_out, zstream.avail_out);
goto z_bail;
}
/* write when we're full or when we're done */
if (zstream.avail_out == 0 ||
(zerr == Z_STREAM_END && zstream.avail_out != sizeof(writeBuf)))
{
long writeSize = zstream.next_out - writeBuf;
int cc = write(fd, writeBuf, writeSize);
if (cc != (int) writeSize) {
LOGW("write failed in inflate (%d vs %ld)\n", cc, writeSize);
goto z_bail;
}
zstream.next_out = writeBuf;
zstream.avail_out = sizeof(writeBuf);
}
} while (zerr == Z_OK);
assert(zerr == Z_STREAM_END); /* other errors should've been caught */
/* paranoia */
if (zstream.total_out != uncompLen) {
LOGW("Size mismatch on inflated file (%ld vs %zd)\n",
zstream.total_out, uncompLen);
goto z_bail;
}
result = true;
z_bail:
inflateEnd(&zstream); /* free up any allocated structures */
bail:
return result;
}