libs/utils/Asset.cpp - SHIFTPHONES/android_frameworks_base - Gitiles

 /*
  * Copyright (C) 2006 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.
  */

 //
 // Provide access to a read-only asset.
 //

 #define LOG_TAG "asset"
 //#define NDEBUG 0

 #include <utils/Asset.h>
 #include <utils/Atomic.h>
 #include <utils/FileMap.h>
 #include <utils/ZipUtils.h>
 #include <utils/ZipFileRO.h>
 #include <utils/Log.h>

 #include <string.h>
 #include <memory.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <assert.h>

 using namespace android;

 #ifndef O_BINARY
 # define O_BINARY 0
 #endif

 static volatile int32_t gCount = 0;

 int32_t Asset::getGlobalCount()
 {
     return gCount;
 }

 Asset::Asset(void)
     : mAccessMode(ACCESS_UNKNOWN)
 {
     int count = android_atomic_inc(&gCount)+1;
     //LOGI("Creating Asset %p #%d\n", this, count);
 }

 Asset::~Asset(void)
 {
     int count = android_atomic_dec(&gCount);
     //LOGI("Destroying Asset in %p #%d\n", this, count);
 }

 /*
  * Create a new Asset from a file on disk.  There is a fair chance that
  * the file doesn't actually exist.
  *
  * We can use "mode" to decide how we want to go about it.
  */
 /*static*/ Asset* Asset::createFromFile(const char* fileName, AccessMode mode)
 {
     _FileAsset* pAsset;
     status_t result;
     off_t length;
     int fd;

     fd = open(fileName, O_RDONLY | O_BINARY);
     if (fd < 0)
         return NULL;

     /*
      * Under Linux, the lseek fails if we actually opened a directory.  To
      * be correct we should test the file type explicitly, but since we
      * always open things read-only it doesn't really matter, so there's
      * no value in incurring the extra overhead of an fstat() call.
      */
     length = lseek(fd, 0, SEEK_END);
     if (length < 0) {
         ::close(fd);
         return NULL;
     }
     (void) lseek(fd, 0, SEEK_SET);

     pAsset = new _FileAsset;
     result = pAsset->openChunk(fileName, fd, 0, length);
     if (result != NO_ERROR) {
         delete pAsset;
         return NULL;
     }

     pAsset->mAccessMode = mode;
     return pAsset;
 }


 /*
  * Create a new Asset from a compressed file on disk.  There is a fair chance
  * that the file doesn't actually exist.
  *
  * We currently support gzip files.  We might want to handle .bz2 someday.
  */
 /*static*/ Asset* Asset::createFromCompressedFile(const char* fileName,
     AccessMode mode)
 {
     _CompressedAsset* pAsset;
     status_t result;
     off_t fileLen;
     bool scanResult;
     long offset;
     int method;
     long uncompressedLen, compressedLen;
     int fd;

     fd = open(fileName, O_RDONLY | O_BINARY);
     if (fd < 0)
         return NULL;

     fileLen = lseek(fd, 0, SEEK_END);
     if (fileLen < 0) {
         ::close(fd);
         return NULL;
     }
     (void) lseek(fd, 0, SEEK_SET);

     /* want buffered I/O for the file scan; must dup so fclose() is safe */
     FILE* fp = fdopen(dup(fd), "rb");
     if (fp == NULL) {
         ::close(fd);
         return NULL;
     }

     unsigned long crc32;
     scanResult = ZipUtils::examineGzip(fp, &method, &uncompressedLen,
                     &compressedLen, &crc32);
     offset = ftell(fp);
     fclose(fp);
     if (!scanResult) {
         LOGD("File '%s' is not in gzip format\n", fileName);
         ::close(fd);
         return NULL;
     }

     pAsset = new _CompressedAsset;
     result = pAsset->openChunk(fd, offset, method, uncompressedLen,
                 compressedLen);
     if (result != NO_ERROR) {
         delete pAsset;
         return NULL;
     }

     pAsset->mAccessMode = mode;
     return pAsset;
 }


 #if 0
 /*
  * Create a new Asset from part of an open file.
  */
 /*static*/ Asset* Asset::createFromFileSegment(int fd, off_t offset,
     size_t length, AccessMode mode)
 {
     _FileAsset* pAsset;
     status_t result;

     pAsset = new _FileAsset;
     result = pAsset->openChunk(NULL, fd, offset, length);
     if (result != NO_ERROR)
         return NULL;

     pAsset->mAccessMode = mode;
     return pAsset;
 }

 /*
  * Create a new Asset from compressed data in an open file.
  */
 /*static*/ Asset* Asset::createFromCompressedData(int fd, off_t offset,
     int compressionMethod, size_t uncompressedLen, size_t compressedLen,
     AccessMode mode)
 {
     _CompressedAsset* pAsset;
     status_t result;

     pAsset = new _CompressedAsset;
     result = pAsset->openChunk(fd, offset, compressionMethod,
                 uncompressedLen, compressedLen);
     if (result != NO_ERROR)
         return NULL;

     pAsset->mAccessMode = mode;
     return pAsset;
 }
 #endif

 /*
  * Create a new Asset from a memory mapping.
  */
 /*static*/ Asset* Asset::createFromUncompressedMap(FileMap* dataMap,
     AccessMode mode)
 {
     _FileAsset* pAsset;
     status_t result;

     pAsset = new _FileAsset;
     result = pAsset->openChunk(dataMap);
     if (result != NO_ERROR)
         return NULL;

     pAsset->mAccessMode = mode;
     return pAsset;
 }

 /*
  * Create a new Asset from compressed data in a memory mapping.
  */
 /*static*/ Asset* Asset::createFromCompressedMap(FileMap* dataMap,
     int method, size_t uncompressedLen, AccessMode mode)
 {
     _CompressedAsset* pAsset;
     status_t result;

     pAsset = new _CompressedAsset;
     result = pAsset->openChunk(dataMap, method, uncompressedLen);
     if (result != NO_ERROR)
         return NULL;

     pAsset->mAccessMode = mode;
     return pAsset;
 }


 /*
  * Do generic seek() housekeeping.  Pass in the offset/whence values from
  * the seek request, along with the current chunk offset and the chunk
  * length.
  *
  * Returns the new chunk offset, or -1 if the seek is illegal.
  */
 off_t Asset::handleSeek(off_t offset, int whence, off_t curPosn, off_t maxPosn)
 {
     off_t newOffset;

     switch (whence) {
     case SEEK_SET:
         newOffset = offset;
         break;
     case SEEK_CUR:
         newOffset = curPosn + offset;
         break;
     case SEEK_END:
         newOffset = maxPosn + offset;
         break;
     default:
         LOGW("unexpected whence %d\n", whence);
         // this was happening due to an off_t size mismatch
         assert(false);
         return (off_t) -1;
     }

     if (newOffset < 0 || newOffset > maxPosn) {
         LOGW("seek out of range: want %ld, end=%ld\n",
             (long) newOffset, (long) maxPosn);
         return (off_t) -1;
     }

     return newOffset;
 }


 /*
  * ===========================================================================
  *      _FileAsset
  * ===========================================================================
  */

 /*
  * Constructor.
  */
 _FileAsset::_FileAsset(void)
     : mStart(0), mLength(0), mOffset(0), mFp(NULL), mFileName(NULL), mMap(NULL), mBuf(NULL)
 {
 }

 /*
  * Destructor.  Release resources.
  */
 _FileAsset::~_FileAsset(void)
 {
     close();
 }

 /*
  * Operate on a chunk of an uncompressed file.
  *
  * Zero-length chunks are allowed.
  */
 status_t _FileAsset::openChunk(const char* fileName, int fd, off_t offset, size_t length)
 {
     assert(mFp == NULL);    // no reopen
     assert(mMap == NULL);
     assert(fd >= 0);
     assert(offset >= 0);

     /*
      * Seek to end to get file length.
      */
     off_t fileLength;
     fileLength = lseek(fd, 0, SEEK_END);
     if (fileLength == (off_t) -1) {
         // probably a bad file descriptor
         LOGD("failed lseek (errno=%d)\n", errno);
         return UNKNOWN_ERROR;
     }

     if ((off_t) (offset + length) > fileLength) {
         LOGD("start (%ld) + len (%ld) > end (%ld)\n",
             (long) offset, (long) length, (long) fileLength);
         return BAD_INDEX;
     }

     /* after fdopen, the fd will be closed on fclose() */
     mFp = fdopen(fd, "rb");
     if (mFp == NULL)
         return UNKNOWN_ERROR;

     mStart = offset;
     mLength = length;
     assert(mOffset == 0);

     /* seek the FILE* to the start of chunk */
     if (fseek(mFp, mStart, SEEK_SET) != 0) {
         assert(false);
     }

     mFileName = fileName != NULL ? strdup(fileName) : NULL;

     return NO_ERROR;
 }

 /*
  * Create the chunk from the map.
  */
 status_t _FileAsset::openChunk(FileMap* dataMap)
 {
     assert(mFp == NULL);    // no reopen
     assert(mMap == NULL);
     assert(dataMap != NULL);

     mMap = dataMap;
     mStart = -1;            // not used
     mLength = dataMap->getDataLength();
     assert(mOffset == 0);

     return NO_ERROR;
 }

 /*
  * Read a chunk of data.
  */
 ssize_t _FileAsset::read(void* buf, size_t count)
 {
     size_t maxLen;
     size_t actual;

     assert(mOffset >= 0 && mOffset <= mLength);

     if (getAccessMode() == ACCESS_BUFFER) {
         /*
          * On first access, read or map the entire file.  The caller has
          * requested buffer access, either because they're going to be
          * using the buffer or because what they're doing has appropriate
          * performance needs and access patterns.
          */
         if (mBuf == NULL)
             getBuffer(false);
     }

     /* adjust count if we're near EOF */
     maxLen = mLength - mOffset;
     if (count > maxLen)
         count = maxLen;

     if (!count)
         return 0;

     if (mMap != NULL) {
         /* copy from mapped area */
         //printf("map read\n");
         memcpy(buf, (char*)mMap->getDataPtr() + mOffset, count);
         actual = count;
     } else if (mBuf != NULL) {
         /* copy from buffer */
         //printf("buf read\n");
         memcpy(buf, (char*)mBuf + mOffset, count);
         actual = count;
     } else {
         /* read from the file */
         //printf("file read\n");
         if (ftell(mFp) != mStart + mOffset) {
             LOGE("Hosed: %ld != %ld+%ld\n",
                 ftell(mFp), (long) mStart, (long) mOffset);
             assert(false);
         }

         /*
          * This returns 0 on error or eof.  We need to use ferror() or feof()
          * to tell the difference, but we don't currently have those on the
          * device.  However, we know how much data is *supposed* to be in the
          * file, so if we don't read the full amount we know something is
          * hosed.
          */
         actual = fread(buf, 1, count, mFp);
         if (actual == 0)        // something failed -- I/O error?
             return -1;

         assert(actual == count);
     }

     mOffset += actual;
     return actual;
 }

 /*
  * Seek to a new position.
  */
 off_t _FileAsset::seek(off_t offset, int whence)
 {
     off_t newPosn;
     long actualOffset;

     // compute new position within chunk
     newPosn = handleSeek(offset, whence, mOffset, mLength);
     if (newPosn == (off_t) -1)
         return newPosn;

     actualOffset = (long) (mStart + newPosn);

     if (mFp != NULL) {
         if (fseek(mFp, (long) actualOffset, SEEK_SET) != 0)
             return (off_t) -1;
     }

     mOffset = actualOffset - mStart;
     return mOffset;
 }

 /*
  * Close the asset.
  */
 void _FileAsset::close(void)
 {
     if (mMap != NULL) {
         mMap->release();
         mMap = NULL;
     }
     if (mBuf != NULL) {
         delete[] mBuf;
         mBuf = NULL;
     }

     if (mFileName != NULL) {
         free(mFileName);
         mFileName = NULL;
     }

     if (mFp != NULL) {
         // can only be NULL when called from destructor
         // (otherwise we would never return this object)
         fclose(mFp);
         mFp = NULL;
     }
 }

 /*
  * Return a read-only pointer to a buffer.
  *
  * We can either read the whole thing in or map the relevant piece of
  * the source file.  Ideally a map would be established at a higher
  * level and we'd be using a different object, but we didn't, so we
  * deal with it here.
  */
 const void* _FileAsset::getBuffer(bool wordAligned)
 {
     /* subsequent requests just use what we did previously */
     if (mBuf != NULL)
         return mBuf;
     if (mMap != NULL) {
         if (!wordAligned) {
             return  mMap->getDataPtr();
         }
         return ensureAlignment(mMap);
     }

     assert(mFp != NULL);

     if (mLength < kReadVsMapThreshold) {
         unsigned char* buf;
         long allocLen;

         /* zero-length files are allowed; not sure about zero-len allocs */
         /* (works fine with gcc + x86linux) */
         allocLen = mLength;
         if (mLength == 0)
             allocLen = 1;

         buf = new unsigned char[allocLen];
         if (buf == NULL) {
             LOGE("alloc of %ld bytes failed\n", (long) allocLen);
             return NULL;
         }

         LOGV("Asset %p allocating buffer size %d (smaller than threshold)", this, (int)allocLen);
         if (mLength > 0) {
             long oldPosn = ftell(mFp);
             fseek(mFp, mStart, SEEK_SET);
             if (fread(buf, 1, mLength, mFp) != (size_t) mLength) {
                 LOGE("failed reading %ld bytes\n", (long) mLength);
                 delete[] buf;
                 return NULL;
             }
             fseek(mFp, oldPosn, SEEK_SET);
         }

         LOGV(" getBuffer: loaded into buffer\n");

         mBuf = buf;
         return mBuf;
     } else {
         FileMap* map;

         map = new FileMap;
         if (!map->create(NULL, fileno(mFp), mStart, mLength, true)) {
             map->release();
             return NULL;
         }

         LOGV(" getBuffer: mapped\n");

         mMap = map;
         if (!wordAligned) {
             return  mMap->getDataPtr();
         }
         return ensureAlignment(mMap);
     }
 }

 int _FileAsset::openFileDescriptor(off_t* outStart, off_t* outLength) const
 {
     if (mMap != NULL) {
         const char* fname = mMap->getFileName();
         if (fname == NULL) {
             fname = mFileName;
         }
         if (fname == NULL) {
             return -1;
         }
         *outStart = mMap->getDataOffset();
         *outLength = mMap->getDataLength();
         return open(fname, O_RDONLY | O_BINARY);
     }
     if (mFileName == NULL) {
         return -1;
     }
     *outStart = mStart;
     *outLength = mLength;
     return open(mFileName, O_RDONLY | O_BINARY);
 }

 const void* _FileAsset::ensureAlignment(FileMap* map)
 {
     void* data = map->getDataPtr();
     if ((((size_t)data)&0x3) == 0) {
         // We can return this directly if it is aligned on a word
         // boundary.
         LOGV("Returning aligned FileAsset %p (%s).", this,
                 getAssetSource());
         return data;
     }
     // If not aligned on a word boundary, then we need to copy it into
     // our own buffer.
     LOGV("Copying FileAsset %p (%s) to buffer size %d to make it aligned.", this,
             getAssetSource(), (int)mLength);
     unsigned char* buf = new unsigned char[mLength];
     if (buf == NULL) {
         LOGE("alloc of %ld bytes failed\n", (long) mLength);
         return NULL;
     }
     memcpy(buf, data, mLength);
     mBuf = buf;
     return buf;
 }

 /*
  * ===========================================================================
  *      _CompressedAsset
  * ===========================================================================
  */

 /*
  * Constructor.
  */
 _CompressedAsset::_CompressedAsset(void)
     : mStart(0), mCompressedLen(0), mUncompressedLen(0), mOffset(0),
       mMap(NULL), mFd(-1), mBuf(NULL)
 {
 }

 /*
  * Destructor.  Release resources.
  */
 _CompressedAsset::~_CompressedAsset(void)
 {
     close();
 }

 /*
  * Open a chunk of compressed data inside a file.
  *
  * This currently just sets up some values and returns.  On the first
  * read, we expand the entire file into a buffer and return data from it.
  */
 status_t _CompressedAsset::openChunk(int fd, off_t offset,
     int compressionMethod, size_t uncompressedLen, size_t compressedLen)
 {
     assert(mFd < 0);        // no re-open
     assert(mMap == NULL);
     assert(fd >= 0);
     assert(offset >= 0);
     assert(compressedLen > 0);

     if (compressionMethod != ZipFileRO::kCompressDeflated) {
         assert(false);
         return UNKNOWN_ERROR;
     }

     mStart = offset;
     mCompressedLen = compressedLen;
     mUncompressedLen = uncompressedLen;
     assert(mOffset == 0);
     mFd = fd;
     assert(mBuf == NULL);

     return NO_ERROR;
 }

 /*
  * Open a chunk of compressed data in a mapped region.
  *
  * Nothing is expanded until the first read call.
  */
 status_t _CompressedAsset::openChunk(FileMap* dataMap, int compressionMethod,
     size_t uncompressedLen)
 {
     assert(mFd < 0);        // no re-open
     assert(mMap == NULL);
     assert(dataMap != NULL);

     if (compressionMethod != ZipFileRO::kCompressDeflated) {
         assert(false);
         return UNKNOWN_ERROR;
     }

     mMap = dataMap;
     mStart = -1;        // not used
     mCompressedLen = dataMap->getDataLength();
     mUncompressedLen = uncompressedLen;
     assert(mOffset == 0);

     return NO_ERROR;
 }

 /*
  * Read data from a chunk of compressed data.
  *
  * [For now, that's just copying data out of a buffer.]
  */
 ssize_t _CompressedAsset::read(void* buf, size_t count)
 {
     size_t maxLen;
     size_t actual;

     assert(mOffset >= 0 && mOffset <= mUncompressedLen);

     // TODO: if mAccessMode == ACCESS_STREAMING, use zlib more cleverly

     if (mBuf == NULL) {
         if (getBuffer(false) == NULL)
             return -1;
     }
     assert(mBuf != NULL);

     /* adjust count if we're near EOF */
     maxLen = mUncompressedLen - mOffset;
     if (count > maxLen)
         count = maxLen;

     if (!count)
         return 0;

     /* copy from buffer */
     //printf("comp buf read\n");
     memcpy(buf, (char*)mBuf + mOffset, count);
     actual = count;

     mOffset += actual;
     return actual;
 }

 /*
  * Handle a seek request.
  *
  * If we're working in a streaming mode, this is going to be fairly
  * expensive, because it requires plowing through a bunch of compressed
  * data.
  */
 off_t _CompressedAsset::seek(off_t offset, int whence)
 {
     off_t newPosn;

     // compute new position within chunk
     newPosn = handleSeek(offset, whence, mOffset, mUncompressedLen);
     if (newPosn == (off_t) -1)
         return newPosn;

     mOffset = newPosn;
     return mOffset;
 }

 /*
  * Close the asset.
  */
 void _CompressedAsset::close(void)
 {
     if (mMap != NULL) {
         mMap->release();
         mMap = NULL;
     }
     if (mBuf != NULL) {
         delete[] mBuf;
         mBuf = NULL;
     }

     if (mFd > 0) {
         ::close(mFd);
         mFd = -1;
     }
 }

 /*
  * Get a pointer to a read-only buffer of data.
  *
  * The first time this is called, we expand the compressed data into a
  * buffer.
  */
 const void* _CompressedAsset::getBuffer(bool wordAligned)
 {
     unsigned char* buf = NULL;

     if (mBuf != NULL)
         return mBuf;

     if (mUncompressedLen > UNCOMPRESS_DATA_MAX) {
         LOGD("Data exceeds UNCOMPRESS_DATA_MAX (%ld vs %d)\n",
             (long) mUncompressedLen, UNCOMPRESS_DATA_MAX);
         goto bail;
     }

     /*
      * Allocate a buffer and read the file into it.
      */
     buf = new unsigned char[mUncompressedLen];
     if (buf == NULL) {
         LOGW("alloc %ld bytes failed\n", (long) mUncompressedLen);
         goto bail;
     }

     if (mMap != NULL) {
         if (!ZipFileRO::inflateBuffer(buf, mMap->getDataPtr(),
                 mUncompressedLen, mCompressedLen))
             goto bail;
     } else {
         assert(mFd >= 0);

         /*
          * Seek to the start of the compressed data.
          */
         if (lseek(mFd, mStart, SEEK_SET) != mStart)
             goto bail;

         /*
          * Expand the data into it.
          */
         if (!ZipUtils::inflateToBuffer(mFd, buf, mUncompressedLen,
                 mCompressedLen))
             goto bail;
     }

     /* success! */
     mBuf = buf;
     buf = NULL;

 bail:
     delete[] buf;
     return mBuf;
 }
	/*
	* Copyright (C) 2006 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.
	*/

	//
	// Provide access to a read-only asset.
	//

	#define LOG_TAG "asset"
	//#define NDEBUG 0

	#include <utils/Asset.h>
	#include <utils/Atomic.h>
	#include <utils/FileMap.h>
	#include <utils/ZipUtils.h>
	#include <utils/ZipFileRO.h>
	#include <utils/Log.h>

	#include <string.h>
	#include <memory.h>
	#include <fcntl.h>
	#include <errno.h>
	#include <assert.h>

	using namespace android;

	#ifndef O_BINARY
	# define O_BINARY 0
	#endif

	static volatile int32_t gCount = 0;

	int32_t Asset::getGlobalCount()
	{
	return gCount;
	}

	Asset::Asset(void)
	: mAccessMode(ACCESS_UNKNOWN)
	{
	int count = android_atomic_inc(&gCount)+1;
	//LOGI("Creating Asset %p #%d\n", this, count);
	}

	Asset::~Asset(void)
	{
	int count = android_atomic_dec(&gCount);
	//LOGI("Destroying Asset in %p #%d\n", this, count);
	}

	/*
	* Create a new Asset from a file on disk. There is a fair chance that
	* the file doesn't actually exist.
	*
	* We can use "mode" to decide how we want to go about it.
	*/
	/static/ Asset* Asset::createFromFile(const char* fileName, AccessMode mode)
	{
	_FileAsset* pAsset;
	status_t result;
	off_t length;
	int fd;

	fd = open(fileName, O_RDONLY \| O_BINARY);
	if (fd < 0)
	return NULL;

	/*
	* Under Linux, the lseek fails if we actually opened a directory. To
	* be correct we should test the file type explicitly, but since we
	* always open things read-only it doesn't really matter, so there's
	* no value in incurring the extra overhead of an fstat() call.
	*/
	length = lseek(fd, 0, SEEK_END);
	if (length < 0) {
	::close(fd);
	return NULL;
	}
	(void) lseek(fd, 0, SEEK_SET);

	pAsset = new _FileAsset;
	result = pAsset->openChunk(fileName, fd, 0, length);
	if (result != NO_ERROR) {
	delete pAsset;
	return NULL;
	}

	pAsset->mAccessMode = mode;
	return pAsset;
	}


	/*
	* Create a new Asset from a compressed file on disk. There is a fair chance
	* that the file doesn't actually exist.
	*
	* We currently support gzip files. We might want to handle .bz2 someday.
	*/
	/static/ Asset* Asset::createFromCompressedFile(const char* fileName,
	AccessMode mode)
	{
	_CompressedAsset* pAsset;
	status_t result;
	off_t fileLen;
	bool scanResult;
	long offset;
	int method;
	long uncompressedLen, compressedLen;
	int fd;

	fd = open(fileName, O_RDONLY \| O_BINARY);
	if (fd < 0)
	return NULL;

	fileLen = lseek(fd, 0, SEEK_END);
	if (fileLen < 0) {
	::close(fd);
	return NULL;
	}
	(void) lseek(fd, 0, SEEK_SET);

	/* want buffered I/O for the file scan; must dup so fclose() is safe */
	FILE* fp = fdopen(dup(fd), "rb");
	if (fp == NULL) {
	::close(fd);
	return NULL;
	}

	unsigned long crc32;
	scanResult = ZipUtils::examineGzip(fp, &method, &uncompressedLen,
	&compressedLen, &crc32);
	offset = ftell(fp);
	fclose(fp);
	if (!scanResult) {
	LOGD("File '%s' is not in gzip format\n", fileName);
	::close(fd);
	return NULL;
	}

	pAsset = new _CompressedAsset;
	result = pAsset->openChunk(fd, offset, method, uncompressedLen,
	compressedLen);
	if (result != NO_ERROR) {
	delete pAsset;
	return NULL;
	}

	pAsset->mAccessMode = mode;
	return pAsset;
	}


	#if 0
	/*
	* Create a new Asset from part of an open file.
	*/
	/static/ Asset* Asset::createFromFileSegment(int fd, off_t offset,
	size_t length, AccessMode mode)
	{
	_FileAsset* pAsset;
	status_t result;

	pAsset = new _FileAsset;
	result = pAsset->openChunk(NULL, fd, offset, length);
	if (result != NO_ERROR)
	return NULL;

	pAsset->mAccessMode = mode;
	return pAsset;
	}

	/*
	* Create a new Asset from compressed data in an open file.
	*/
	/static/ Asset* Asset::createFromCompressedData(int fd, off_t offset,
	int compressionMethod, size_t uncompressedLen, size_t compressedLen,
	AccessMode mode)
	{
	_CompressedAsset* pAsset;
	status_t result;

	pAsset = new _CompressedAsset;
	result = pAsset->openChunk(fd, offset, compressionMethod,
	uncompressedLen, compressedLen);
	if (result != NO_ERROR)
	return NULL;

	pAsset->mAccessMode = mode;
	return pAsset;
	}
	#endif

	/*
	* Create a new Asset from a memory mapping.
	*/
	/static/ Asset* Asset::createFromUncompressedMap(FileMap* dataMap,
	AccessMode mode)
	{
	_FileAsset* pAsset;
	status_t result;

	pAsset = new _FileAsset;
	result = pAsset->openChunk(dataMap);
	if (result != NO_ERROR)
	return NULL;

	pAsset->mAccessMode = mode;
	return pAsset;
	}

	/*
	* Create a new Asset from compressed data in a memory mapping.
	*/
	/static/ Asset* Asset::createFromCompressedMap(FileMap* dataMap,
	int method, size_t uncompressedLen, AccessMode mode)
	{
	_CompressedAsset* pAsset;
	status_t result;

	pAsset = new _CompressedAsset;
	result = pAsset->openChunk(dataMap, method, uncompressedLen);
	if (result != NO_ERROR)
	return NULL;

	pAsset->mAccessMode = mode;
	return pAsset;
	}


	/*
	* Do generic seek() housekeeping. Pass in the offset/whence values from
	* the seek request, along with the current chunk offset and the chunk
	* length.
	*
	* Returns the new chunk offset, or -1 if the seek is illegal.
	*/
	off_t Asset::handleSeek(off_t offset, int whence, off_t curPosn, off_t maxPosn)
	{
	off_t newOffset;

	switch (whence) {
	case SEEK_SET:
	newOffset = offset;
	break;
	case SEEK_CUR:
	newOffset = curPosn + offset;
	break;
	case SEEK_END:
	newOffset = maxPosn + offset;
	break;
	default:
	LOGW("unexpected whence %d\n", whence);
	// this was happening due to an off_t size mismatch
	assert(false);
	return (off_t) -1;
	}

	if (newOffset < 0 \|\| newOffset > maxPosn) {
	LOGW("seek out of range: want %ld, end=%ld\n",
	(long) newOffset, (long) maxPosn);
	return (off_t) -1;
	}

	return newOffset;
	}


	/*
	* ===========================================================================
	* _FileAsset
	* ===========================================================================
	*/

	/*
	* Constructor.
	*/
	_FileAsset::_FileAsset(void)
	: mStart(0), mLength(0), mOffset(0), mFp(NULL), mFileName(NULL), mMap(NULL), mBuf(NULL)
	{
	}

	/*
	* Destructor. Release resources.
	*/
	_FileAsset::~_FileAsset(void)
	{
	close();
	}

	/*
	* Operate on a chunk of an uncompressed file.
	*
	* Zero-length chunks are allowed.
	*/
	status_t _FileAsset::openChunk(const char* fileName, int fd, off_t offset, size_t length)
	{
	assert(mFp == NULL); // no reopen
	assert(mMap == NULL);
	assert(fd >= 0);
	assert(offset >= 0);

	/*
	* Seek to end to get file length.
	*/
	off_t fileLength;
	fileLength = lseek(fd, 0, SEEK_END);
	if (fileLength == (off_t) -1) {
	// probably a bad file descriptor
	LOGD("failed lseek (errno=%d)\n", errno);
	return UNKNOWN_ERROR;
	}

	if ((off_t) (offset + length) > fileLength) {
	LOGD("start (%ld) + len (%ld) > end (%ld)\n",
	(long) offset, (long) length, (long) fileLength);
	return BAD_INDEX;
	}

	/* after fdopen, the fd will be closed on fclose() */
	mFp = fdopen(fd, "rb");
	if (mFp == NULL)
	return UNKNOWN_ERROR;

	mStart = offset;
	mLength = length;
	assert(mOffset == 0);

	/* seek the FILE* to the start of chunk */
	if (fseek(mFp, mStart, SEEK_SET) != 0) {
	assert(false);
	}

	mFileName = fileName != NULL ? strdup(fileName) : NULL;

	return NO_ERROR;
	}

	/*
	* Create the chunk from the map.
	*/
	status_t _FileAsset::openChunk(FileMap* dataMap)
	{
	assert(mFp == NULL); // no reopen
	assert(mMap == NULL);
	assert(dataMap != NULL);

	mMap = dataMap;
	mStart = -1; // not used
	mLength = dataMap->getDataLength();
	assert(mOffset == 0);

	return NO_ERROR;
	}

	/*
	* Read a chunk of data.
	*/
	ssize_t _FileAsset::read(void* buf, size_t count)
	{
	size_t maxLen;
	size_t actual;

	assert(mOffset >= 0 && mOffset <= mLength);

	if (getAccessMode() == ACCESS_BUFFER) {
	/*
	* On first access, read or map the entire file. The caller has
	* requested buffer access, either because they're going to be
	* using the buffer or because what they're doing has appropriate
	* performance needs and access patterns.
	*/
	if (mBuf == NULL)
	getBuffer(false);
	}

	/* adjust count if we're near EOF */
	maxLen = mLength - mOffset;
	if (count > maxLen)
	count = maxLen;

	if (!count)
	return 0;

	if (mMap != NULL) {
	/* copy from mapped area */
	//printf("map read\n");
	memcpy(buf, (char*)mMap->getDataPtr() + mOffset, count);
	actual = count;
	} else if (mBuf != NULL) {
	/* copy from buffer */
	//printf("buf read\n");
	memcpy(buf, (char*)mBuf + mOffset, count);
	actual = count;
	} else {
	/* read from the file */
	//printf("file read\n");
	if (ftell(mFp) != mStart + mOffset) {
	LOGE("Hosed: %ld != %ld+%ld\n",
	ftell(mFp), (long) mStart, (long) mOffset);
	assert(false);
	}

	/*
	* This returns 0 on error or eof. We need to use ferror() or feof()
	* to tell the difference, but we don't currently have those on the
	* device. However, we know how much data is supposed to be in the
	* file, so if we don't read the full amount we know something is
	* hosed.
	*/
	actual = fread(buf, 1, count, mFp);
	if (actual == 0) // something failed -- I/O error?
	return -1;

	assert(actual == count);
	}

	mOffset += actual;
	return actual;
	}

	/*
	* Seek to a new position.
	*/
	off_t _FileAsset::seek(off_t offset, int whence)
	{
	off_t newPosn;
	long actualOffset;

	// compute new position within chunk
	newPosn = handleSeek(offset, whence, mOffset, mLength);
	if (newPosn == (off_t) -1)
	return newPosn;

	actualOffset = (long) (mStart + newPosn);

	if (mFp != NULL) {
	if (fseek(mFp, (long) actualOffset, SEEK_SET) != 0)
	return (off_t) -1;
	}

	mOffset = actualOffset - mStart;
	return mOffset;
	}

	/*
	* Close the asset.
	*/
	void _FileAsset::close(void)
	{
	if (mMap != NULL) {
	mMap->release();
	mMap = NULL;
	}
	if (mBuf != NULL) {
	delete[] mBuf;
	mBuf = NULL;
	}

	if (mFileName != NULL) {
	free(mFileName);
	mFileName = NULL;
	}

	if (mFp != NULL) {
	// can only be NULL when called from destructor
	// (otherwise we would never return this object)
	fclose(mFp);
	mFp = NULL;
	}
	}

	/*
	* Return a read-only pointer to a buffer.
	*
	* We can either read the whole thing in or map the relevant piece of
	* the source file. Ideally a map would be established at a higher
	* level and we'd be using a different object, but we didn't, so we
	* deal with it here.
	*/
	const void* _FileAsset::getBuffer(bool wordAligned)
	{
	/* subsequent requests just use what we did previously */
	if (mBuf != NULL)
	return mBuf;
	if (mMap != NULL) {
	if (!wordAligned) {
	return mMap->getDataPtr();
	}
	return ensureAlignment(mMap);
	}

	assert(mFp != NULL);

	if (mLength < kReadVsMapThreshold) {
	unsigned char* buf;
	long allocLen;

	/* zero-length files are allowed; not sure about zero-len allocs */
	/* (works fine with gcc + x86linux) */
	allocLen = mLength;
	if (mLength == 0)
	allocLen = 1;

	buf = new unsigned char[allocLen];
	if (buf == NULL) {
	LOGE("alloc of %ld bytes failed\n", (long) allocLen);
	return NULL;
	}

	LOGV("Asset %p allocating buffer size %d (smaller than threshold)", this, (int)allocLen);
	if (mLength > 0) {
	long oldPosn = ftell(mFp);
	fseek(mFp, mStart, SEEK_SET);
	if (fread(buf, 1, mLength, mFp) != (size_t) mLength) {
	LOGE("failed reading %ld bytes\n", (long) mLength);
	delete[] buf;
	return NULL;
	}
	fseek(mFp, oldPosn, SEEK_SET);
	}

	LOGV(" getBuffer: loaded into buffer\n");

	mBuf = buf;
	return mBuf;
	} else {
	FileMap* map;

	map = new FileMap;
	if (!map->create(NULL, fileno(mFp), mStart, mLength, true)) {
	map->release();
	return NULL;
	}

	LOGV(" getBuffer: mapped\n");

	mMap = map;
	if (!wordAligned) {
	return mMap->getDataPtr();
	}
	return ensureAlignment(mMap);
	}
	}

	int _FileAsset::openFileDescriptor(off_t* outStart, off_t* outLength) const
	{
	if (mMap != NULL) {
	const char* fname = mMap->getFileName();
	if (fname == NULL) {
	fname = mFileName;
	}
	if (fname == NULL) {
	return -1;
	}
	*outStart = mMap->getDataOffset();
	*outLength = mMap->getDataLength();
	return open(fname, O_RDONLY \| O_BINARY);
	}
	if (mFileName == NULL) {
	return -1;
	}
	*outStart = mStart;
	*outLength = mLength;
	return open(mFileName, O_RDONLY \| O_BINARY);
	}

	const void* _FileAsset::ensureAlignment(FileMap* map)
	{
	void* data = map->getDataPtr();
	if ((((size_t)data)&0x3) == 0) {
	// We can return this directly if it is aligned on a word
	// boundary.
	LOGV("Returning aligned FileAsset %p (%s).", this,
	getAssetSource());
	return data;
	}
	// If not aligned on a word boundary, then we need to copy it into
	// our own buffer.
	LOGV("Copying FileAsset %p (%s) to buffer size %d to make it aligned.", this,
	getAssetSource(), (int)mLength);
	unsigned char* buf = new unsigned char[mLength];
	if (buf == NULL) {
	LOGE("alloc of %ld bytes failed\n", (long) mLength);
	return NULL;
	}
	memcpy(buf, data, mLength);
	mBuf = buf;
	return buf;
	}

	/*
	* ===========================================================================
	* _CompressedAsset
	* ===========================================================================
	*/

	/*
	* Constructor.
	*/
	_CompressedAsset::_CompressedAsset(void)
	: mStart(0), mCompressedLen(0), mUncompressedLen(0), mOffset(0),
	mMap(NULL), mFd(-1), mBuf(NULL)
	{
	}

	/*
	* Destructor. Release resources.
	*/
	_CompressedAsset::~_CompressedAsset(void)
	{
	close();
	}

	/*
	* Open a chunk of compressed data inside a file.
	*
	* This currently just sets up some values and returns. On the first
	* read, we expand the entire file into a buffer and return data from it.
	*/
	status_t _CompressedAsset::openChunk(int fd, off_t offset,
	int compressionMethod, size_t uncompressedLen, size_t compressedLen)
	{
	assert(mFd < 0); // no re-open
	assert(mMap == NULL);
	assert(fd >= 0);
	assert(offset >= 0);
	assert(compressedLen > 0);

	if (compressionMethod != ZipFileRO::kCompressDeflated) {
	assert(false);
	return UNKNOWN_ERROR;
	}

	mStart = offset;
	mCompressedLen = compressedLen;
	mUncompressedLen = uncompressedLen;
	assert(mOffset == 0);
	mFd = fd;
	assert(mBuf == NULL);

	return NO_ERROR;
	}

	/*
	* Open a chunk of compressed data in a mapped region.
	*
	* Nothing is expanded until the first read call.
	*/
	status_t _CompressedAsset::openChunk(FileMap* dataMap, int compressionMethod,
	size_t uncompressedLen)
	{
	assert(mFd < 0); // no re-open
	assert(mMap == NULL);
	assert(dataMap != NULL);

	if (compressionMethod != ZipFileRO::kCompressDeflated) {
	assert(false);
	return UNKNOWN_ERROR;
	}

	mMap = dataMap;
	mStart = -1; // not used
	mCompressedLen = dataMap->getDataLength();
	mUncompressedLen = uncompressedLen;
	assert(mOffset == 0);

	return NO_ERROR;
	}

	/*
	* Read data from a chunk of compressed data.
	*
	* [For now, that's just copying data out of a buffer.]
	*/
	ssize_t _CompressedAsset::read(void* buf, size_t count)
	{
	size_t maxLen;
	size_t actual;

	assert(mOffset >= 0 && mOffset <= mUncompressedLen);

	// TODO: if mAccessMode == ACCESS_STREAMING, use zlib more cleverly

	if (mBuf == NULL) {
	if (getBuffer(false) == NULL)
	return -1;
	}
	assert(mBuf != NULL);

	/* adjust count if we're near EOF */
	maxLen = mUncompressedLen - mOffset;
	if (count > maxLen)
	count = maxLen;

	if (!count)
	return 0;

	/* copy from buffer */
	//printf("comp buf read\n");
	memcpy(buf, (char*)mBuf + mOffset, count);
	actual = count;

	mOffset += actual;
	return actual;
	}

	/*
	* Handle a seek request.
	*
	* If we're working in a streaming mode, this is going to be fairly
	* expensive, because it requires plowing through a bunch of compressed
	* data.
	*/
	off_t _CompressedAsset::seek(off_t offset, int whence)
	{
	off_t newPosn;

	// compute new position within chunk
	newPosn = handleSeek(offset, whence, mOffset, mUncompressedLen);
	if (newPosn == (off_t) -1)
	return newPosn;

	mOffset = newPosn;
	return mOffset;
	}

	/*
	* Close the asset.
	*/
	void _CompressedAsset::close(void)
	{
	if (mMap != NULL) {
	mMap->release();
	mMap = NULL;
	}
	if (mBuf != NULL) {
	delete[] mBuf;
	mBuf = NULL;
	}

	if (mFd > 0) {
	::close(mFd);
	mFd = -1;
	}
	}

	/*
	* Get a pointer to a read-only buffer of data.
	*
	* The first time this is called, we expand the compressed data into a
	* buffer.
	*/
	const void* _CompressedAsset::getBuffer(bool wordAligned)
	{
	unsigned char* buf = NULL;

	if (mBuf != NULL)
	return mBuf;

	if (mUncompressedLen > UNCOMPRESS_DATA_MAX) {
	LOGD("Data exceeds UNCOMPRESS_DATA_MAX (%ld vs %d)\n",
	(long) mUncompressedLen, UNCOMPRESS_DATA_MAX);
	goto bail;
	}

	/*
	* Allocate a buffer and read the file into it.
	*/
	buf = new unsigned char[mUncompressedLen];
	if (buf == NULL) {
	LOGW("alloc %ld bytes failed\n", (long) mUncompressedLen);
	goto bail;
	}

	if (mMap != NULL) {
	if (!ZipFileRO::inflateBuffer(buf, mMap->getDataPtr(),
	mUncompressedLen, mCompressedLen))
	goto bail;
	} else {
	assert(mFd >= 0);

	/*
	* Seek to the start of the compressed data.
	*/
	if (lseek(mFd, mStart, SEEK_SET) != mStart)
	goto bail;

	/*
	* Expand the data into it.
	*/
	if (!ZipUtils::inflateToBuffer(mFd, buf, mUncompressedLen,
	mCompressedLen))
	goto bail;
	}

	/* success! */
	mBuf = buf;
	buf = NULL;

	bail:
	delete[] buf;
	return mBuf;
	}