--- /dev/null
+/*
+ * 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.
+ *
+ * This is similar to the more-complete ZipFile class, but no attempt
+ * has been made to make them interchangeable. This class operates under
+ * a very different set of assumptions and constraints.
+ *
+ * One such assumption is that if you're getting file descriptors for
+ * use with this class as a child of a fork() operation, you must be on
+ * a pread() to guarantee correct operation. This is because pread() can
+ * atomically read at a file offset without worrying about a lock around an
+ * lseek() + read() pair.
+ */
+#ifndef __LIBS_ZIPFILERO_H
+#define __LIBS_ZIPFILERO_H
+
+#include <utils/Compat.h>
+#include <utils/Errors.h>
+#include <utils/FileMap.h>
+#include <utils/threads.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+
+namespace android {
+
+/*
+ * Trivial typedef to ensure that ZipEntryRO is not treated as a simple
+ * integer. We use NULL to indicate an invalid value.
+ */
+typedef void* ZipEntryRO;
+
+/*
+ * Open a Zip archive for reading.
+ *
+ * We want "open" and "find entry by name" to be fast operations, and we
+ * want to use as little memory as possible. We memory-map the file,
+ * and load a hash table with pointers to the filenames (which aren't
+ * null-terminated). The other fields are at a fixed offset from the
+ * filename, so we don't need to extract those (but we do need to byte-read
+ * and endian-swap them every time we want them).
+ *
+ * To speed comparisons when doing a lookup by name, we could make the mapping
+ * "private" (copy-on-write) and null-terminate the filenames after verifying
+ * the record structure. However, this requires a private mapping of
+ * every page that the Central Directory touches. Easier to tuck a copy
+ * of the string length into the hash table entry.
+ *
+ * NOTE: If this is used on file descriptors inherited from a fork() operation,
+ * you must be on a platform that implements pread() to guarantee correctness
+ * on the shared file descriptors.
+ */
+class ZipFileRO {
+public:
+ ZipFileRO()
+ : mFd(-1), mFileName(NULL), mFileLength(-1),
+ mDirectoryMap(NULL),
+ mNumEntries(-1), mDirectoryOffset(-1),
+ mHashTableSize(-1), mHashTable(NULL)
+ {}
+
+ ~ZipFileRO();
+
+ /*
+ * Open an archive.
+ */
+ status_t open(const char* zipFileName);
+
+ /*
+ * Find an entry, by name. Returns the entry identifier, or NULL if
+ * not found.
+ *
+ * If two entries have the same name, one will be chosen at semi-random.
+ */
+ ZipEntryRO findEntryByName(const char* fileName) const;
+
+ /*
+ * Return the #of entries in the Zip archive.
+ */
+ int getNumEntries(void) const {
+ return mNumEntries;
+ }
+
+ /*
+ * Return the Nth entry. Zip file entries are not stored in sorted
+ * order, and updated entries may appear at the end, so anyone walking
+ * the archive needs to avoid making ordering assumptions. We take
+ * that further by returning the Nth non-empty entry in the hash table
+ * rather than the Nth entry in the archive.
+ *
+ * Valid values are [0..numEntries).
+ *
+ * [This is currently O(n). If it needs to be fast we can allocate an
+ * additional data structure or provide an iterator interface.]
+ */
+ ZipEntryRO findEntryByIndex(int idx) const;
+
+ /*
+ * Copy the filename into the supplied buffer. Returns 0 on success,
+ * -1 if "entry" is invalid, or the filename length if it didn't fit. The
+ * length, and the returned string, include the null-termination.
+ */
+ int getEntryFileName(ZipEntryRO entry, char* buffer, int bufLen) const;
+
+ /*
+ * Get the vital stats for an entry. Pass in NULL pointers for anything
+ * you don't need.
+ *
+ * "*pOffset" holds the Zip file offset of the entry's data.
+ *
+ * Returns "false" if "entry" is bogus or if the data in the Zip file
+ * appears to be bad.
+ */
+ bool getEntryInfo(ZipEntryRO entry, int* pMethod, size_t* pUncompLen,
+ size_t* pCompLen, off64_t* pOffset, long* pModWhen, long* pCrc32) const;
+
+ /*
+ * Create a new FileMap object that maps a subset of the archive. For
+ * an uncompressed entry this effectively provides a pointer to the
+ * actual data, for a compressed entry this provides the input buffer
+ * for inflate().
+ */
+ FileMap* createEntryFileMap(ZipEntryRO entry) const;
+
+ /*
+ * Uncompress the data into a buffer. Depending on the compression
+ * format, this is either an "inflate" operation or a memcpy.
+ *
+ * Use "uncompLen" from getEntryInfo() to determine the required
+ * buffer size.
+ *
+ * Returns "true" on success.
+ */
+ bool uncompressEntry(ZipEntryRO entry, void* buffer) const;
+
+ /*
+ * Uncompress the data to an open file descriptor.
+ */
+ bool uncompressEntry(ZipEntryRO entry, int fd) const;
+
+ /* Zip compression methods we support */
+ enum {
+ kCompressStored = 0, // no compression
+ kCompressDeflated = 8, // standard deflate
+ };
+
+ /*
+ * Utility function: uncompress deflated data, buffer to buffer.
+ */
+ static bool inflateBuffer(void* outBuf, const void* inBuf,
+ size_t uncompLen, size_t compLen);
+
+ /*
+ * Utility function: uncompress deflated data, buffer to fd.
+ */
+ static bool inflateBuffer(int fd, const void* inBuf,
+ size_t uncompLen, size_t compLen);
+
+ /*
+ * Utility function to convert ZIP's time format to a timespec struct.
+ */
+ static inline void zipTimeToTimespec(long when, struct tm* timespec) {
+ const long date = when >> 16;
+ timespec->tm_year = ((date >> 9) & 0x7F) + 80; // Zip is years since 1980
+ timespec->tm_mon = (date >> 5) & 0x0F;
+ timespec->tm_mday = date & 0x1F;
+
+ timespec->tm_hour = (when >> 11) & 0x1F;
+ timespec->tm_min = (when >> 5) & 0x3F;
+ timespec->tm_sec = (when & 0x1F) << 1;
+ }
+
+ /*
+ * Some basic functions for raw data manipulation. "LE" means
+ * Little Endian.
+ */
+ static inline unsigned short get2LE(const unsigned char* buf) {
+ return buf[0] | (buf[1] << 8);
+ }
+ static inline unsigned long get4LE(const unsigned char* buf) {
+ return buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
+ }
+
+private:
+ /* these are private and not defined */
+ ZipFileRO(const ZipFileRO& src);
+ ZipFileRO& operator=(const ZipFileRO& src);
+
+ /* locate and parse the central directory */
+ bool mapCentralDirectory(void);
+
+ /* parse the archive, prepping internal structures */
+ bool parseZipArchive(void);
+
+ /* add a new entry to the hash table */
+ void addToHash(const char* str, int strLen, unsigned int hash);
+
+ /* compute string hash code */
+ static unsigned int computeHash(const char* str, int len);
+
+ /* convert a ZipEntryRO back to a hash table index */
+ int entryToIndex(const ZipEntryRO entry) const;
+
+ /*
+ * One entry in the hash table.
+ */
+ typedef struct HashEntry {
+ const char* name;
+ unsigned short nameLen;
+ //unsigned int hash;
+ } HashEntry;
+
+ /* open Zip archive */
+ int mFd;
+
+ /* Lock for handling the file descriptor (seeks, etc) */
+ mutable Mutex mFdLock;
+
+ /* zip file name */
+ char* mFileName;
+
+ /* length of file */
+ size_t mFileLength;
+
+ /* mapped file */
+ FileMap* mDirectoryMap;
+
+ /* number of entries in the Zip archive */
+ int mNumEntries;
+
+ /* CD directory offset in the Zip archive */
+ off64_t mDirectoryOffset;
+
+ /*
+ * We know how many entries are in the Zip archive, so we have a
+ * fixed-size hash table. We probe for an empty slot.
+ */
+ int mHashTableSize;
+ HashEntry* mHashTable;
+};
+
+}; // namespace android
+
+#endif /*__LIBS_ZIPFILERO_H*/
--- /dev/null
+/*
+ * 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/Log.h>
+#include <utils/ZipFileRO.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>
+
+#if HAVE_PRINTF_ZD
+# define ZD "%zd"
+# define ZD_TYPE ssize_t
+#else
+# define ZD "%ld"
+# define ZD_TYPE long
+#endif
+
+/*
+ * We must open binary files using open(path, ... | O_BINARY) under Windows.
+ * Otherwise strange read errors will happen.
+ */
+#ifndef O_BINARY
+# define O_BINARY 0
+#endif
+
+/*
+ * 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) {
+ ALOGW("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 | O_BINARY);
+ if (fd < 0) {
+ ALOGW("Unable to open zip '%s': %s\n", zipFileName, strerror(errno));
+ return NAME_NOT_FOUND;
+ }
+
+ mFileLength = lseek64(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)
+{
+ ssize_t readAmount = kMaxEOCDSearch;
+ if (readAmount > (ssize_t) mFileLength)
+ readAmount = mFileLength;
+
+ unsigned char* scanBuf = (unsigned char*) malloc(readAmount);
+ if (scanBuf == NULL) {
+ ALOGW("couldn't allocate scanBuf: %s", strerror(errno));
+ free(scanBuf);
+ return false;
+ }
+
+ /*
+ * Make sure this is a Zip archive.
+ */
+ if (lseek64(mFd, 0, SEEK_SET) != 0) {
+ ALOGW("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)) {
+ ALOGI("couldn't read first signature from zip archive: %s", strerror(errno));
+ free(scanBuf);
+ return false;
+ }
+
+ {
+ unsigned int header = get4LE(scanBuf);
+ if (header == kEOCDSignature) {
+ ALOGI("Found Zip archive, but it looks empty\n");
+ free(scanBuf);
+ return false;
+ } else if (header != kLFHSignature) {
+ ALOGV("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.
+ */
+ off64_t searchStart = mFileLength - readAmount;
+
+ if (lseek64(mFd, searchStart, SEEK_SET) != searchStart) {
+ ALOGW("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) {
+ ALOGW("Zip: read " ZD ", expected " ZD ". Failed: %s\n",
+ (ZD_TYPE) actual, (ZD_TYPE) 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) {
+ ALOGV("+++ Found EOCD at buf+%d\n", i);
+ break;
+ }
+ }
+ if (i < 0) {
+ ALOGD("Zip: EOCD not found, %s is not zip\n", mFileName);
+ free(scanBuf);
+ return false;
+ }
+
+ off64_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) {
+ ALOGW("bad offsets (dir %ld, size %u, eocd %ld)\n",
+ (long) dirOffset, dirSize, (long) eocdOffset);
+ return false;
+ }
+ if (numEntries == 0) {
+ ALOGW("empty archive?\n");
+ return false;
+ }
+
+ ALOGV("+++ numEntries=%d dirSize=%d dirOffset=%d\n",
+ numEntries, dirSize, dirOffset);
+
+ mDirectoryMap = new FileMap();
+ if (mDirectoryMap == NULL) {
+ ALOGW("Unable to create directory map: %s", strerror(errno));
+ return false;
+ }
+
+ if (!mDirectoryMap->create(mFileName, mFd, dirOffset, dirSize, true)) {
+ ALOGW("Unable to map '%s' (" ZD " to " ZD "): %s\n", mFileName,
+ (ZD_TYPE) dirOffset, (ZD_TYPE) (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) {
+ ALOGW("Missed a central dir sig (at %d)\n", i);
+ goto bail;
+ }
+ if (ptr + kCDELen > cdPtr + cdLength) {
+ ALOGW("Ran off the end (at %d)\n", i);
+ goto bail;
+ }
+
+ long localHdrOffset = (long) get4LE(ptr + kCDELocalOffset);
+ if (localHdrOffset >= mDirectoryOffset) {
+ ALOGW("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) {
+ ALOGW("bad CD advance (%d vs " ZD ") at entry %d\n",
+ (int) (ptr - cdPtr), (ZD_TYPE) cdLength, i);
+ goto bail;
+ }
+ }
+ ALOGV("+++ 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 NULL if not found.
+ */
+ZipEntryRO ZipFileRO::findEntryByName(const char* fileName) const
+{
+ /*
+ * If the ZipFileRO instance is not initialized, the entry number will
+ * end up being garbage since mHashTableSize is -1.
+ */
+ if (mHashTableSize <= 0) {
+ return NULL;
+ }
+
+ 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) {
+ ALOGW("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, off64_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;
+ off64_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) {
+ ALOGE("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 pread64() instead of a lseek64() + read() to
+ * guarantee atomicity across the processes with the shared file
+ * descriptors.
+ */
+ ssize_t actual =
+ TEMP_FAILURE_RETRY(pread64(mFd, lfhBuf, sizeof(lfhBuf), localHdrOffset));
+
+ if (actual != sizeof(lfhBuf)) {
+ ALOGW("failed reading lfh from offset %ld\n", localHdrOffset);
+ return false;
+ }
+
+ if (get4LE(lfhBuf) != kLFHSignature) {
+ ALOGW("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 pread64() 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 lseek64() concurrently.
+ */
+
+ {
+ AutoMutex _l(mFdLock);
+
+ if (lseek64(mFd, localHdrOffset, SEEK_SET) != localHdrOffset) {
+ ALOGW("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)) {
+ ALOGW("failed reading lfh from offset %ld\n", localHdrOffset);
+ return false;
+ }
+
+ if (get4LE(lfhBuf) != kLFHSignature) {
+ off64_t actualOffset = lseek64(mFd, 0, SEEK_CUR);
+ ALOGW("didn't find signature at start of lfh; wanted: offset=%ld data=0x%08x; "
+ "got: offset=" ZD " data=0x%08lx\n",
+ localHdrOffset, kLFHSignature, (ZD_TYPE) actualOffset, get4LE(lfhBuf));
+ return false;
+ }
+ }
+#endif /* HAVE_PREAD */
+
+ off64_t dataOffset = localHdrOffset + kLFHLen
+ + get2LE(lfhBuf + kLFHNameLen) + get2LE(lfhBuf + kLFHExtraLen);
+ if (dataOffset >= cdOffset) {
+ ALOGW("bad data offset %ld in zip\n", (long) dataOffset);
+ return false;
+ }
+
+ /* check lengths */
+ if ((off64_t)(dataOffset + compLen) > cdOffset) {
+ ALOGW("bad compressed length in zip (%ld + " ZD " > %ld)\n",
+ (long) dataOffset, (ZD_TYPE) compLen, (long) cdOffset);
+ return false;
+ }
+
+ if (method == kCompressStored &&
+ (off64_t)(dataOffset + uncompLen) > cdOffset)
+ {
+ ALOGE("ERROR: bad uncompressed length in zip (%ld + " ZD " > %ld)\n",
+ (long) dataOffset, (ZD_TYPE) 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;
+ off64_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;
+ off64_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;
+ off64_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) {
+ ALOGE("Write failed: %s\n", strerror(errno));
+ goto unmap;
+ } else if ((size_t) actual != uncompLen) {
+ ALOGE("Partial write during uncompress (" ZD " of " ZD ")\n",
+ (ZD_TYPE) actual, (ZD_TYPE) uncompLen);
+ goto unmap;
+ } else {
+ ALOGI("+++ 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) {
+ ALOGE("Installed zlib is not compatible with linked version (%s)\n",
+ ZLIB_VERSION);
+ } else {
+ ALOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
+ }
+ goto bail;
+ }
+
+ /*
+ * Expand data.
+ */
+ zerr = inflate(&zstream, Z_FINISH);
+ if (zerr != Z_STREAM_END) {
+ ALOGW("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) {
+ ALOGW("Size mismatch on inflated file (%ld vs " ZD ")\n",
+ zstream.total_out, (ZD_TYPE) 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) {
+ ALOGE("Installed zlib is not compatible with linked version (%s)\n",
+ ZLIB_VERSION);
+ } else {
+ ALOGE("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) {
+ ALOGW("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) {
+ ALOGW("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) {
+ ALOGW("Size mismatch on inflated file (%ld vs " ZD ")\n",
+ zstream.total_out, (ZD_TYPE) uncompLen);
+ goto z_bail;
+ }
+
+ result = true;
+
+z_bail:
+ inflateEnd(&zstream); /* free up any allocated structures */
+
+bail:
+ return result;
+}
--- /dev/null
+/*
+ * 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.
+ */
+
+//
+// Misc zip/gzip utility functions.
+//
+
+#define LOG_TAG "ziputil"
+
+#include <utils/Log.h>
+#include <utils/ZipUtils.h>
+#include <utils/ZipFileRO.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include <zlib.h>
+
+using namespace android;
+
+/*
+ * Utility function that expands zip/gzip "deflate" compressed data
+ * into a buffer.
+ *
+ * "fd" is an open file positioned at the start of the "deflate" data
+ * "buf" must hold at least "uncompressedLen" bytes.
+ */
+/*static*/ bool ZipUtils::inflateToBuffer(int fd, void* buf,
+ long uncompressedLen, long compressedLen)
+{
+ bool result = false;
+ const unsigned long kReadBufSize = 32768;
+ unsigned char* readBuf = NULL;
+ z_stream zstream;
+ int zerr;
+ unsigned long compRemaining;
+
+ assert(uncompressedLen >= 0);
+ assert(compressedLen >= 0);
+
+ readBuf = new unsigned char[kReadBufSize];
+ if (readBuf == NULL)
+ goto bail;
+ compRemaining = compressedLen;
+
+ /*
+ * Initialize the zlib stream.
+ */
+ 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 = (Bytef*) buf;
+ zstream.avail_out = uncompressedLen;
+ 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) {
+ ALOGE("Installed zlib is not compatible with linked version (%s)\n",
+ ZLIB_VERSION);
+ } else {
+ ALOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
+ }
+ goto bail;
+ }
+
+ /*
+ * Loop while we have data.
+ */
+ do {
+ unsigned long getSize;
+
+ /* read as much as we can */
+ if (zstream.avail_in == 0) {
+ getSize = (compRemaining > kReadBufSize) ?
+ kReadBufSize : compRemaining;
+ ALOGV("+++ reading %ld bytes (%ld left)\n",
+ getSize, compRemaining);
+
+ int cc = read(fd, readBuf, getSize);
+ if (cc != (int) getSize) {
+ ALOGD("inflate read failed (%d vs %ld)\n",
+ cc, getSize);
+ goto z_bail;
+ }
+
+ compRemaining -= getSize;
+
+ zstream.next_in = readBuf;
+ zstream.avail_in = getSize;
+ }
+
+ /* uncompress the data */
+ zerr = inflate(&zstream, Z_NO_FLUSH);
+ if (zerr != Z_OK && zerr != Z_STREAM_END) {
+ ALOGD("zlib inflate call failed (zerr=%d)\n", zerr);
+ goto z_bail;
+ }
+
+ /* output buffer holds all, so no need to write the output */
+ } while (zerr == Z_OK);
+
+ assert(zerr == Z_STREAM_END); /* other errors should've been caught */
+
+ if ((long) zstream.total_out != uncompressedLen) {
+ ALOGW("Size mismatch on inflated file (%ld vs %ld)\n",
+ zstream.total_out, uncompressedLen);
+ goto z_bail;
+ }
+
+ // success!
+ result = true;
+
+z_bail:
+ inflateEnd(&zstream); /* free up any allocated structures */
+
+bail:
+ delete[] readBuf;
+ return result;
+}
+
+/*
+ * Utility function that expands zip/gzip "deflate" compressed data
+ * into a buffer.
+ *
+ * (This is a clone of the previous function, but it takes a FILE* instead
+ * of an fd. We could pass fileno(fd) to the above, but we can run into
+ * trouble when "fp" has a different notion of what fd's file position is.)
+ *
+ * "fp" is an open file positioned at the start of the "deflate" data
+ * "buf" must hold at least "uncompressedLen" bytes.
+ */
+/*static*/ bool ZipUtils::inflateToBuffer(FILE* fp, void* buf,
+ long uncompressedLen, long compressedLen)
+{
+ bool result = false;
+ const unsigned long kReadBufSize = 32768;
+ unsigned char* readBuf = NULL;
+ z_stream zstream;
+ int zerr;
+ unsigned long compRemaining;
+
+ assert(uncompressedLen >= 0);
+ assert(compressedLen >= 0);
+
+ readBuf = new unsigned char[kReadBufSize];
+ if (readBuf == NULL)
+ goto bail;
+ compRemaining = compressedLen;
+
+ /*
+ * Initialize the zlib stream.
+ */
+ 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 = (Bytef*) buf;
+ zstream.avail_out = uncompressedLen;
+ 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) {
+ ALOGE("Installed zlib is not compatible with linked version (%s)\n",
+ ZLIB_VERSION);
+ } else {
+ ALOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
+ }
+ goto bail;
+ }
+
+ /*
+ * Loop while we have data.
+ */
+ do {
+ unsigned long getSize;
+
+ /* read as much as we can */
+ if (zstream.avail_in == 0) {
+ getSize = (compRemaining > kReadBufSize) ?
+ kReadBufSize : compRemaining;
+ ALOGV("+++ reading %ld bytes (%ld left)\n",
+ getSize, compRemaining);
+
+ int cc = fread(readBuf, 1, getSize, fp);
+ if (cc != (int) getSize) {
+ ALOGD("inflate read failed (%d vs %ld)\n",
+ cc, getSize);
+ goto z_bail;
+ }
+
+ compRemaining -= getSize;
+
+ zstream.next_in = readBuf;
+ zstream.avail_in = getSize;
+ }
+
+ /* uncompress the data */
+ zerr = inflate(&zstream, Z_NO_FLUSH);
+ if (zerr != Z_OK && zerr != Z_STREAM_END) {
+ ALOGD("zlib inflate call failed (zerr=%d)\n", zerr);
+ goto z_bail;
+ }
+
+ /* output buffer holds all, so no need to write the output */
+ } while (zerr == Z_OK);
+
+ assert(zerr == Z_STREAM_END); /* other errors should've been caught */
+
+ if ((long) zstream.total_out != uncompressedLen) {
+ ALOGW("Size mismatch on inflated file (%ld vs %ld)\n",
+ zstream.total_out, uncompressedLen);
+ goto z_bail;
+ }
+
+ // success!
+ result = true;
+
+z_bail:
+ inflateEnd(&zstream); /* free up any allocated structures */
+
+bail:
+ delete[] readBuf;
+ return result;
+}
+
+/*
+ * Look at the contents of a gzip archive. We want to know where the
+ * data starts, and how long it will be after it is uncompressed.
+ *
+ * We expect to find the CRC and length as the last 8 bytes on the file.
+ * This is a pretty reasonable thing to expect for locally-compressed
+ * files, but there's a small chance that some extra padding got thrown
+ * on (the man page talks about compressed data written to tape). We
+ * don't currently deal with that here. If "gzip -l" whines, we're going
+ * to fail too.
+ *
+ * On exit, "fp" is pointing at the start of the compressed data.
+ */
+/*static*/ bool ZipUtils::examineGzip(FILE* fp, int* pCompressionMethod,
+ long* pUncompressedLen, long* pCompressedLen, unsigned long* pCRC32)
+{
+ enum { // flags
+ FTEXT = 0x01,
+ FHCRC = 0x02,
+ FEXTRA = 0x04,
+ FNAME = 0x08,
+ FCOMMENT = 0x10,
+ };
+ int ic;
+ int method, flags;
+ int i;
+
+ ic = getc(fp);
+ if (ic != 0x1f || getc(fp) != 0x8b)
+ return false; // not gzip
+ method = getc(fp);
+ flags = getc(fp);
+
+ /* quick sanity checks */
+ if (method == EOF || flags == EOF)
+ return false;
+ if (method != ZipFileRO::kCompressDeflated)
+ return false;
+
+ /* skip over 4 bytes of mod time, 1 byte XFL, 1 byte OS */
+ for (i = 0; i < 6; i++)
+ (void) getc(fp);
+ /* consume "extra" field, if present */
+ if ((flags & FEXTRA) != 0) {
+ int len;
+
+ len = getc(fp);
+ len |= getc(fp) << 8;
+ while (len-- && getc(fp) != EOF)
+ ;
+ }
+ /* consume filename, if present */
+ if ((flags & FNAME) != 0) {
+ do {
+ ic = getc(fp);
+ } while (ic != 0 && ic != EOF);
+ }
+ /* consume comment, if present */
+ if ((flags & FCOMMENT) != 0) {
+ do {
+ ic = getc(fp);
+ } while (ic != 0 && ic != EOF);
+ }
+ /* consume 16-bit header CRC, if present */
+ if ((flags & FHCRC) != 0) {
+ (void) getc(fp);
+ (void) getc(fp);
+ }
+
+ if (feof(fp) || ferror(fp))
+ return false;
+
+ /* seek to the end; CRC and length are in the last 8 bytes */
+ long curPosn = ftell(fp);
+ unsigned char buf[8];
+ fseek(fp, -8, SEEK_END);
+ *pCompressedLen = ftell(fp) - curPosn;
+
+ if (fread(buf, 1, 8, fp) != 8)
+ return false;
+ /* seek back to start of compressed data */
+ fseek(fp, curPosn, SEEK_SET);
+
+ *pCompressionMethod = method;
+ *pCRC32 = ZipFileRO::get4LE(&buf[0]);
+ *pUncompressedLen = ZipFileRO::get4LE(&buf[4]);
+
+ return true;
+}