ZipUtilsRO rewrite based on Dalvik Zip rewrite

Change the way zip archives are handled.  This is necessary to deal with
very large (~1GB) APK files, for which our current approach of mapping
the entire file falls over.

We now do the classic scavenger hunt for the End Of Central Directory
magic on a buffer of data read from the file, instead of a memory-mapped
section.  We use what we find to create a map that covers the Central
Directory only.

If the caller is interested in unpacking the file contents, we have to
do an additional file read to discover the size of the Local File Header
section so we can skip past it.

This is based on Change I745fb15abb in the dalvik tree. Both
implementations share a common ancestry, but the cost of unifying them
outweighs the benefits of wrapping C calls.

Change-Id: Iddacb50fe913917c2845708a530872d65fdbe620

3 files changed, 299 insertions, 169 deletions

diff --git a/libs/utils/AssetManager.cpp b/libs/utils/AssetManager.cpp
index 5a05e6a..60a0d82 100644
--- a/libs/utils/AssetManager.cpp
+++ b/libs/utils/AssetManager.cpp
@@ -824,7 +824,7 @@ Asset* AssetManager::openAssetFromZipLocked(const ZipFileRO* pZipFile,
 
     // TODO: look for previously-created shared memory slice?
     int method;
-    long uncompressedLen;
+    size_t uncompressedLen;
 
     //printf("USING Zip '%s'\n", pEntry->getFileName());
 
diff --git a/libs/utils/ZipFileCRO.cpp b/libs/utils/ZipFileCRO.cpp
index 45f6c8b..16b219c 100644
--- a/libs/utils/ZipFileCRO.cpp
+++ b/libs/utils/ZipFileCRO.cpp
@@ -39,8 +39,8 @@ ZipEntryCRO ZipFileCRO_findEntryByName(ZipFileCRO zipToken,
 }
 
 bool ZipFileCRO_getEntryInfo(ZipFileCRO zipToken, ZipEntryRO entryToken,
-        int* pMethod, long* pUncompLen,
-        long* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) {
+        int* pMethod, size_t* pUncompLen,
+        size_t* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) {
     ZipFileRO* zip = (ZipFileRO*)zipToken;
     ZipEntryRO entry = (ZipEntryRO)entryToken;
     return zip->getEntryInfo(entry, pMethod, pUncompLen, pCompLen, pOffset,
diff --git a/libs/utils/ZipFileRO.cpp b/libs/utils/ZipFileRO.cpp
index 6c701dd..28dc512 100644
--- a/libs/utils/ZipFileRO.cpp
+++ b/libs/utils/ZipFileRO.cpp
@@ -29,6 +29,22 @@
 #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;
 
@@ -38,6 +54,7 @@ using namespace android;
 #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
@@ -90,9 +107,8 @@ int ZipFileRO::entryToIndex(const ZipEntryRO entry) const
 status_t ZipFileRO::open(const char* zipFileName)
 {
     int fd = -1;
-    off_t length;
 
-    assert(mFileMap == NULL);
+    assert(mDirectoryMap == NULL);
 
     /*
      * Open and map the specified file.
@@ -103,172 +119,240 @@ status_t ZipFileRO::open(const char* zipFileName)
         return NAME_NOT_FOUND;
     }
 
-    length = lseek(fd, 0, SEEK_END);
-    if (length < 0) {
+    mFileLength = lseek(fd, 0, SEEK_END);
+    if (mFileLength < kEOCDLen) {
         close(fd);
         return UNKNOWN_ERROR;
     }
 
-    mFileMap = new FileMap();
-    if (mFileMap == NULL) {
-        close(fd);
-        return NO_MEMORY;
-    }
-    if (!mFileMap->create(zipFileName, fd, 0, length, true)) {
-        LOGW("Unable to map '%s': %s\n", zipFileName, strerror(errno));
-        close(fd);
-        return UNKNOWN_ERROR;
+    if (mFileName != NULL) {
+        free(mFileName);
     }
+    mFileName = strdup(zipFileName);
 
     mFd = fd;
 
     /*
-     * Got it mapped, verify it and create data structures for fast access.
+     * 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()) {
-        mFileMap->release();
-        mFileMap = NULL;
-        return UNKNOWN_ERROR;
+        goto bail;
     }
 
     return OK;
+
+bail:
+    free(mFileName);
+    mFileName = NULL;
+    close(fd);
+    return UNKNOWN_ERROR;
 }
 
 /*
  * Parse the Zip archive, verifying its contents and initializing internal
  * data structures.
  */
-bool ZipFileRO::parseZipArchive(void)
+bool ZipFileRO::mapCentralDirectory(void)
 {
-#define CHECK_OFFSET(_off) {                                                \
-        if ((unsigned int) (_off) >= maxOffset) {                           \
-            LOGE("ERROR: bad offset %u (max %d): %s\n",                     \
-                (unsigned int) (_off), maxOffset, #_off);                   \
-            goto bail;                                                      \
-        }                                                                   \
-    }
-    const unsigned char* basePtr = (const unsigned char*)mFileMap->getDataPtr();
-    const unsigned char* ptr;
-    size_t length = mFileMap->getDataLength();
-    bool result = false;
-    unsigned int i, numEntries, cdOffset;
-    unsigned int val;
+    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;
+    }
 
     /*
-     * The first 4 bytes of the file will either be the local header
-     * signature for the first file (kLFHSignature) or, if the archive doesn't
-     * have any files in it, the end-of-central-directory signature
-     * (kEOCDSignature).
+     * Make sure this is a Zip archive.
      */
-    val = get4LE(basePtr);
-    if (val == kEOCDSignature) {
-        LOGI("Found Zip archive, but it looks empty\n");
-        goto bail;
-    } else if (val != kLFHSignature) {
-        LOGV("Not a Zip archive (found 0x%08x)\n", val);
-        goto bail;
+    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", val);
+            free(scanBuf);
+            return false;
+        }
     }
 
     /*
-     * Find the EOCD.  We'll find it immediately unless they have a file
-     * comment.
+     * 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.
      */
-    ptr = basePtr + length - kEOCDLen;
+    off_t searchStart = mFileLength - readAmount;
 
-    while (ptr >= basePtr) {
-        if (*ptr == (kEOCDSignature & 0xff) && get4LE(ptr) == kEOCDSignature)
+    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;
-        ptr--;
+        }
     }
-    if (ptr < basePtr) {
-        LOGI("Could not find end-of-central-directory in Zip\n");
-        goto bail;
+    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);
+
     /*
-     * There are two interesting items in the EOCD block: the number of
-     * entries in the file, and the file offset of the start of the
-     * central directory.
-     *
-     * (There's actually a count of the #of entries in this file, and for
-     * all files which comprise a spanned archive, but for our purposes
-     * we're only interested in the current file.  Besides, we expect the
-     * two to be equivalent for our stuff.)
+     * Grab the CD offset and size, and the number of entries in the
+     * archive.  Verify that they look reasonable.
      */
-    numEntries = get2LE(ptr + kEOCDNumEntries);
-    cdOffset = get4LE(ptr + kEOCDFileOffset);
+    unsigned int numEntries = get2LE(eocdPtr + kEOCDNumEntries);
+    unsigned int dirSize = get4LE(eocdPtr + kEOCDSize);
+    unsigned int dirOffset = get4LE(eocdPtr + kEOCDFileOffset);
+
+    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);
+        free(scanBuf);
+        return false;
+    }
+    if (numEntries == 0) {
+        LOGW("empty archive?\n");
+        free(scanBuf);
+        return false;
+    }
 
-    /* valid offsets are [0,EOCD] */
-    unsigned int maxOffset;
-    maxOffset = (ptr - basePtr) +1;
+    LOGV("+++ numEntries=%d dirSize=%d dirOffset=%d\n",
+        numEntries, dirSize, dirOffset);
 
-    LOGV("+++ numEntries=%d cdOffset=%d\n", numEntries, cdOffset);
-    if (numEntries == 0 || cdOffset >= length) {
-        LOGW("Invalid entries=%d offset=%d (len=%zd)\n",
-            numEntries, cdOffset, length);
-        goto bail;
+    mDirectoryMap = new FileMap();
+    if (mDirectoryMap == NULL) {
+        LOGW("Unable to create directory map: %s", strerror(errno));
+        free(scanBuf);
+        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));
+        free(scanBuf);
+        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.
      */
-    mNumEntries = numEntries;
-    mHashTableSize = roundUpPower2(1 + ((numEntries * 4) / 3));
-    mHashTable = (HashEntry*) calloc(1, sizeof(HashEntry) * mHashTableSize);
+    mHashTableSize = roundUpPower2(1 + (numEntries * 4) / 3);
+    mHashTable = (HashEntry*) calloc(mHashTableSize, sizeof(HashEntry));
 
     /*
      * Walk through the central directory, adding entries to the hash
      * table.
      */
-    ptr = basePtr + cdOffset;
-    for (i = 0; i < numEntries; i++) {
-        unsigned int fileNameLen, extraLen, commentLen, localHdrOffset;
-        const unsigned char* localHdr;
-        unsigned int hash;
-
+    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 > basePtr + length) {
+        if (ptr + kCDELen > cdPtr + cdLength) {
             LOGW("Ran off the end (at %d)\n", i);
             goto bail;
         }
 
-        localHdrOffset = get4LE(ptr + kCDELocalOffset);
-        CHECK_OFFSET(localHdrOffset);
+        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);
 
-        //LOGV("+++ %d: localHdr=%d fnl=%d el=%d cl=%d\n",
-        //    i, localHdrOffset, fileNameLen, extraLen, commentLen);
-        //LOGV(" '%.*s'\n", fileNameLen, ptr + kCDELen);
-
         /* add the CDE filename to the hash table */
         hash = computeHash((const char*)ptr + kCDELen, fileNameLen);
         addToHash((const char*)ptr + kCDELen, fileNameLen, hash);
 
-        localHdr = basePtr + localHdrOffset;
-        if (get4LE(localHdr) != kLFHSignature) {
-            LOGW("Bad offset to local header: %d (at %d)\n",
-                localHdrOffset, i);
+        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;
         }
-
-        ptr += kCDELen + fileNameLen + extraLen + commentLen;
-        CHECK_OFFSET(ptr - basePtr);
     }
-
+    LOGV("+++ zip good scan %d entries\n", numEntries);
     result = true;
 
 bail:
     return result;
-#undef CHECK_OFFSET
 }
 
-
 /*
  * Simple string hash function for non-null-terminated strings.
  */
@@ -315,7 +399,7 @@ ZipEntryRO ZipFileRO::findEntryByName(const char* fileName) const
             memcmp(mHashTable[ent].name, fileName, nameLen) == 0)
         {
             /* match */
-            return (ZipEntryRO) (ent + kZipEntryAdj);
+            return (ZipEntryRO)(long)(ent + kZipEntryAdj);
         }
 
         ent = (ent + 1) & (mHashTableSize-1);
@@ -354,20 +438,24 @@ ZipEntryRO ZipFileRO::findEntryByIndex(int idx) const
  * 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, long* pUncompLen,
-    long* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) const
+bool ZipFileRO::getEntryInfo(ZipEntryRO entry, int* pMethod, size_t* pUncompLen,
+    size_t* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) const
 {
-    int ent = entryToIndex(entry);
+    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.
+     * pointer.  The filename is the first entry past the fixed-size data,
+     * so we can just subtract back from that.
      */
-    const unsigned char* basePtr = (const unsigned char*)mFileMap->getDataPtr();
-    const unsigned char* ptr = (const unsigned char*) mHashTable[ent].name;
-    size_t zipLength = mFileMap->getDataLength();
+    const unsigned char* ptr = (const unsigned char*) hashEntry.name;
+    off_t cdOffset = mDirectoryOffset;
 
     ptr -= kCDELen;
 
@@ -380,48 +468,78 @@ bool ZipFileRO::getEntryInfo(ZipEntryRO entry, int* pMethod, long* pUncompLen,
     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;
+
     /*
-     * We 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.
+     * 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.
      */
-    unsigned long localHdrOffset = get4LE(ptr + kCDELocalOffset);
-    if (localHdrOffset + kLFHLen >= zipLength) {
-        LOGE("ERROR: bad local hdr offset in zip\n");
-        return false;
-    }
-    const unsigned char* localHdr = basePtr + localHdrOffset;
-    off_t dataOffset = localHdrOffset + kLFHLen
-        + get2LE(localHdr + kLFHNameLen) + get2LE(localHdr + kLFHExtraLen);
-    if ((unsigned long) dataOffset >= zipLength) {
-        LOGE("ERROR: bad data offset in zip\n");
-        return false;
-    }
+    if (pOffset != NULL) {
+        long localHdrOffset = get4LE(ptr + kCDELocalOffset);
+        if (localHdrOffset + kLFHLen >= cdOffset) {
+            LOGE("ERROR: bad local hdr offset in zip\n");
+            return false;
+        }
 
-    if (pCompLen != NULL) {
-        *pCompLen = get4LE(ptr + kCDECompLen);
-        if (*pCompLen < 0 || (size_t)(dataOffset + *pCompLen) >= zipLength) {
-            LOGE("ERROR: bad compressed length in zip\n");
+        unsigned char lfhBuf[kLFHLen];
+        if (lseek(mFd, localHdrOffset, SEEK_SET) != localHdrOffset) {
+            LOGW("failed seeking to lfh at offset %ld\n", localHdrOffset);
             return false;
         }
-    }
-    if (pUncompLen != NULL) {
-        *pUncompLen = get4LE(ptr + kCDEUncompLen);
-        if (*pUncompLen < 0) {
-            LOGE("ERROR: negative uncompressed length in zip\n");
+        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) {
+            LOGW("didn't find signature at start of lfh, offset=%ld\n",
+                localHdrOffset);
             return false;
         }
+
+        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 &&
-            (size_t)(dataOffset + *pUncompLen) >= zipLength)
+            (off_t)(dataOffset + uncompLen) > cdOffset)
         {
-            LOGE("ERROR: bad uncompressed length in zip\n");
+            LOGE("ERROR: bad uncompressed length in zip (%ld + %zd > %ld)\n",
+                (long) dataOffset, uncompLen, (long) cdOffset);
             return false;
         }
-    }
 
-    if (pOffset != NULL) {
         *pOffset = dataOffset;
     }
+
     return true;
 }
 
@@ -457,14 +575,14 @@ FileMap* ZipFileRO::createEntryFileMap(ZipEntryRO entry) const
      */
 
     FileMap* newMap;
-    long compLen;
+    size_t compLen;
     off_t offset;
 
     if (!getEntryInfo(entry, NULL, NULL, &compLen, &offset, NULL, NULL))
         return NULL;
 
     newMap = new FileMap();
-    if (!newMap->create(mFileMap->getFileName(), mFd, offset, compLen, true)) {
+    if (!newMap->create(mFileName, mFd, offset, compLen, true)) {
         newMap->release();
         return NULL;
     }
@@ -480,19 +598,26 @@ FileMap* ZipFileRO::createEntryFileMap(ZipEntryRO entry) const
  */
 bool ZipFileRO::uncompressEntry(ZipEntryRO entry, void* buffer) const
 {
-    const int kSequentialMin = 32768;
+    const size_t kSequentialMin = 32768;
     bool result = false;
     int ent = entryToIndex(entry);
     if (ent < 0)
         return -1;
 
-    const unsigned char* basePtr = (const unsigned char*)mFileMap->getDataPtr();
     int method;
-    long uncompLen, compLen;
+    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
@@ -507,17 +632,17 @@ bool ZipFileRO::uncompressEntry(ZipEntryRO entry, void* buffer) const
      * pair of system calls are negated by a reduction in page faults.
      */
     if (compLen > kSequentialMin)
-        mFileMap->advise(FileMap::SEQUENTIAL);
+        file->advise(FileMap::SEQUENTIAL);
 
     if (method == kCompressStored) {
-        memcpy(buffer, basePtr + offset, uncompLen);
+        memcpy(buffer, ptr, uncompLen);
     } else {
-        if (!inflateBuffer(buffer, basePtr + offset, uncompLen, compLen))
+        if (!inflateBuffer(buffer, ptr, uncompLen, compLen))
             goto bail;
     }
 
     if (compLen > kSequentialMin)
-        mFileMap->advise(FileMap::NORMAL);
+        file->advise(FileMap::NORMAL);
 
     result = true;
 
@@ -537,29 +662,34 @@ bool ZipFileRO::uncompressEntry(ZipEntryRO entry, int fd) const
     if (ent < 0)
         return -1;
 
-    const unsigned char* basePtr = (const unsigned char*)mFileMap->getDataPtr();
     int method;
-    long uncompLen, compLen;
+    size_t uncompLen, compLen;
     off_t offset;
+    const unsigned char* ptr;
 
     getEntryInfo(entry, &method, &uncompLen, &compLen, &offset, NULL, NULL);
 
-    if (method == kCompressStored) {
-        ssize_t actual;
+    const FileMap* file = createEntryFileMap(entry);
+    if (file == NULL) {
+        goto bail;
+    }
+
+    ptr = (const unsigned char*) file->getDataPtr();
 
-        actual = write(fd, basePtr + offset, uncompLen);
+    if (method == kCompressStored) {
+        ssize_t actual = write(fd, ptr, uncompLen);
         if (actual < 0) {
             LOGE("Write failed: %s\n", strerror(errno));
             goto bail;
-        } else if (actual != uncompLen) {
-            LOGE("Partial write during uncompress (%d of %ld)\n",
-                (int)actual, uncompLen);
+        } else if ((size_t) actual != uncompLen) {
+            LOGE("Partial write during uncompress (%zd of %zd)\n",
+                actual, uncompLen);
             goto bail;
         } else {
             LOGI("+++ successful write\n");
         }
     } else {
-        if (!inflateBuffer(fd, basePtr+offset, uncompLen, compLen))
+        if (!inflateBuffer(fd, ptr, uncompLen, compLen))
             goto bail;
     }
 
@@ -573,7 +703,7 @@ bail:
  * Uncompress "deflate" data from one buffer to another.
  */
 /*static*/ bool ZipFileRO::inflateBuffer(void* outBuf, const void* inBuf,
-    long uncompLen, long compLen)
+    size_t uncompLen, size_t compLen)
 {
     bool result = false;
     z_stream zstream;
@@ -582,7 +712,7 @@ bail:
     /*
      * Initialize the zlib stream struct.
      */
-	memset(&zstream, 0, sizeof(zstream));
+    memset(&zstream, 0, sizeof(zstream));
     zstream.zalloc = Z_NULL;
     zstream.zfree = Z_NULL;
     zstream.opaque = Z_NULL;
@@ -592,10 +722,10 @@ bail:
     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.
-	 */
+    /*
+     * 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) {
@@ -619,8 +749,8 @@ bail:
     }
 
     /* paranoia */
-    if ((long) zstream.total_out != uncompLen) {
-        LOGW("Size mismatch on inflated file (%ld vs %ld)\n",
+    if (zstream.total_out != uncompLen) {
+        LOGW("Size mismatch on inflated file (%ld vs %zd)\n",
             zstream.total_out, uncompLen);
         goto z_bail;
     }
@@ -638,10 +768,10 @@ bail:
  * Uncompress "deflate" data from one buffer to an open file descriptor.
  */
 /*static*/ bool ZipFileRO::inflateBuffer(int fd, const void* inBuf,
-    long uncompLen, long compLen)
+    size_t uncompLen, size_t compLen)
 {
     bool result = false;
-    const int kWriteBufSize = 32768;
+    const size_t kWriteBufSize = 32768;
     unsigned char writeBuf[kWriteBufSize];
     z_stream zstream;
     int zerr;
@@ -649,7 +779,7 @@ bail:
     /*
      * Initialize the zlib stream struct.
      */
-	memset(&zstream, 0, sizeof(zstream));
+    memset(&zstream, 0, sizeof(zstream));
     zstream.zalloc = Z_NULL;
     zstream.zfree = Z_NULL;
     zstream.opaque = Z_NULL;
@@ -659,10 +789,10 @@ bail:
     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.
-	 */
+    /*
+     * 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) {
@@ -708,8 +838,8 @@ bail:
     assert(zerr == Z_STREAM_END);       /* other errors should've been caught */
 
     /* paranoia */
-    if ((long) zstream.total_out != uncompLen) {
-        LOGW("Size mismatch on inflated file (%ld vs %ld)\n",
+    if (zstream.total_out != uncompLen) {
+        LOGW("Size mismatch on inflated file (%ld vs %zd)\n",
             zstream.total_out, uncompLen);
         goto z_bail;
     }