Initial Contribution

1 files changed, 1098 insertions, 0 deletions

diff --git a/minzip/Zip.c b/minzip/Zip.c
new file mode 100644
index 0000000..100c833
--- /dev/null
+++ b/minzip/Zip.c
@@ -0,0 +1,1098 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Simple Zip file support.
+ */
+#include "safe_iop.h"
+#include "zlib.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>     // for uintptr_t
+#include <stdlib.h>
+#include <sys/stat.h>   // for S_ISLNK()
+#include <unistd.h>
+
+#define LOG_TAG "minzip"
+#include "Zip.h"
+#include "Bits.h"
+#include "Log.h"
+#include "DirUtil.h"
+
+#undef NDEBUG   // do this after including Log.h
+#include <assert.h>
+
+#define SORT_ENTRIES 1
+
+/*
+ * Offset and length constants (java.util.zip naming convention).
+ */
+enum {
+    CENSIG = 0x02014b50,      // PK12
+    CENHDR = 46,
+
+    CENVEM =  4,
+    CENVER =  6,
+    CENFLG =  8,
+    CENHOW = 10,
+    CENTIM = 12,
+    CENCRC = 16,
+    CENSIZ = 20,
+    CENLEN = 24,
+    CENNAM = 28,
+    CENEXT = 30, 
+    CENCOM = 32,
+    CENDSK = 34,
+    CENATT = 36,
+    CENATX = 38,
+    CENOFF = 42,
+
+    ENDSIG = 0x06054b50,     // PK56
+    ENDHDR = 22,
+
+    ENDSUB =  8,
+    ENDTOT = 10,
+    ENDSIZ = 12,
+    ENDOFF = 16,
+    ENDCOM = 20,
+
+    EXTSIG = 0x08074b50,     // PK78
+    EXTHDR = 16,
+
+    EXTCRC =  4,
+    EXTSIZ =  8,
+    EXTLEN = 12,
+
+    LOCSIG = 0x04034b50,      // PK34
+    LOCHDR = 30,
+        
+    LOCVER =  4,
+    LOCFLG =  6,
+    LOCHOW =  8,
+    LOCTIM = 10,
+    LOCCRC = 14,
+    LOCSIZ = 18, 
+    LOCLEN = 22,
+    LOCNAM = 26,
+    LOCEXT = 28,
+
+    STORED = 0,
+    DEFLATED = 8,
+
+    CENVEM_UNIX = 3 << 8,   // the high byte of CENVEM
+};
+
+
+/*
+ * For debugging, dump the contents of a ZipEntry.
+ */
+#if 0
+static void dumpEntry(const ZipEntry* pEntry)
+{
+    LOGI(" %p '%.*s'\n", pEntry->fileName,pEntry->fileNameLen,pEntry->fileName);
+    LOGI("   off=%ld comp=%ld uncomp=%ld how=%d\n", pEntry->offset,
+        pEntry->compLen, pEntry->uncompLen, pEntry->compression);
+}
+#endif
+
+/*
+ * (This is a mzHashTableLookup callback.)
+ *
+ * Compare two ZipEntry structs, by name.
+ */
+static int hashcmpZipEntry(const void* ventry1, const void* ventry2)
+{
+    const ZipEntry* entry1 = (const ZipEntry*) ventry1;
+    const ZipEntry* entry2 = (const ZipEntry*) ventry2;
+
+    if (entry1->fileNameLen != entry2->fileNameLen)
+        return entry1->fileNameLen - entry2->fileNameLen;
+    return memcmp(entry1->fileName, entry2->fileName, entry1->fileNameLen);
+}
+
+/*
+ * (This is a mzHashTableLookup callback.)
+ *
+ * find a ZipEntry struct by name.
+ */
+static int hashcmpZipName(const void* ventry, const void* vname)
+{
+    const ZipEntry* entry = (const ZipEntry*) ventry;
+    const char* name = (const char*) vname;
+    unsigned int nameLen = strlen(name);
+
+    if (entry->fileNameLen != nameLen)
+        return entry->fileNameLen - nameLen;
+    return memcmp(entry->fileName, name, nameLen);
+}
+
+/*
+ * Compute the hash code for a ZipEntry filename.
+ *
+ * Not expected to be compatible with any other hash function, so we init
+ * to 2 to ensure it doesn't happen to match.
+ */
+static unsigned int computeHash(const char* name, int nameLen)
+{
+    unsigned int hash = 2;
+
+    while (nameLen--)
+        hash = hash * 31 + *name++;
+
+    return hash;
+}
+
+static void addEntryToHashTable(HashTable* pHash, ZipEntry* pEntry)
+{
+    unsigned int itemHash = computeHash(pEntry->fileName, pEntry->fileNameLen);
+    const ZipEntry* found;
+
+    found = (const ZipEntry*)mzHashTableLookup(pHash,
+                itemHash, pEntry, hashcmpZipEntry, true);
+    if (found != pEntry) {
+        LOGW("WARNING: duplicate entry '%.*s' in Zip\n",
+            found->fileNameLen, found->fileName);
+        /* keep going */
+    }
+}
+
+static int validFilename(const char *fileName, unsigned int fileNameLen)
+{
+    // Forbid super long filenames.
+    if (fileNameLen >= PATH_MAX) {
+        LOGW("Filename too long (%d chatacters)\n", fileNameLen);
+        return 0;
+    }
+
+    // Require all characters to be printable ASCII (no NUL, no UTF-8, etc).
+    unsigned int i;
+    for (i = 0; i < fileNameLen; ++i) {
+        if (fileName[i] < 32 || fileName[i] >= 127) {
+            LOGW("Filename contains invalid character '\%03o'\n", fileName[i]);
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Parse the contents of a Zip archive.  After confirming that the file
+ * is in fact a Zip, we scan out the contents of the central directory and
+ * store it in a hash table.
+ *
+ * Returns "true" on success.
+ */
+static bool parseZipArchive(ZipArchive* pArchive, const MemMapping* pMap)
+{
+    bool result = false;
+    const unsigned char* ptr;
+    unsigned int i, numEntries, cdOffset;
+    unsigned int val;
+
+    /*
+     * The first 4 bytes of the file will either be the local header
+     * signature for the first file (LOCSIG) or, if the archive doesn't
+     * have any files in it, the end-of-central-directory signature (ENDSIG).
+     */
+    val = get4LE(pMap->addr);
+    if (val == ENDSIG) {
+        LOGI("Found Zip archive, but it looks empty\n");
+        goto bail;
+    } else if (val != LOCSIG) {
+        LOGV("Not a Zip archive (found 0x%08x)\n", val);
+        goto bail;
+    }
+
+    /*
+     * Find the EOCD.  We'll find it immediately unless they have a file
+     * comment.
+     */
+    ptr = pMap->addr + pMap->length - ENDHDR;
+
+    while (ptr >= (const unsigned char*) pMap->addr) {
+        if (*ptr == (ENDSIG & 0xff) && get4LE(ptr) == ENDSIG)
+            break;
+        ptr--;
+    }
+    if (ptr < (const unsigned char*) pMap->addr) {
+        LOGI("Could not find end-of-central-directory in Zip\n");
+        goto bail;
+    }
+
+    /*
+     * 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.
+     */
+    numEntries = get2LE(ptr + ENDSUB);
+    cdOffset = get4LE(ptr + ENDOFF);
+
+    LOGVV("numEntries=%d cdOffset=%d\n", numEntries, cdOffset);
+    if (numEntries == 0 || cdOffset >= pMap->length) {
+        LOGW("Invalid entries=%d offset=%d (len=%zd)\n",
+            numEntries, cdOffset, pMap->length);
+        goto bail;
+    }
+
+    /*
+     * Create data structures to hold entries.
+     */
+    pArchive->numEntries = numEntries;
+    pArchive->pEntries = (ZipEntry*) calloc(numEntries, sizeof(ZipEntry));
+    pArchive->pHash = mzHashTableCreate(mzHashSize(numEntries), NULL);
+    if (pArchive->pEntries == NULL || pArchive->pHash == NULL)
+        goto bail;
+
+    ptr = pMap->addr + cdOffset;
+    for (i = 0; i < numEntries; i++) {
+        ZipEntry* pEntry;
+        unsigned int fileNameLen, extraLen, commentLen, localHdrOffset;
+        const unsigned char* localHdr;
+        const char *fileName;
+
+        if (ptr + CENHDR > (const unsigned char*)pMap->addr + pMap->length) {
+            LOGW("Ran off the end (at %d)\n", i);
+            goto bail;
+        }
+        if (get4LE(ptr) != CENSIG) {
+            LOGW("Missed a central dir sig (at %d)\n", i);
+            goto bail;
+        }
+
+        localHdrOffset = get4LE(ptr + CENOFF);
+        fileNameLen = get2LE(ptr + CENNAM);
+        extraLen = get2LE(ptr + CENEXT);
+        commentLen = get2LE(ptr + CENCOM);
+        fileName = (const char*)ptr + CENHDR;
+        if (fileName + fileNameLen > (const char*)pMap->addr + pMap->length) {
+            LOGW("Filename ran off the end (at %d)\n", i);
+            goto bail;
+        }
+        if (!validFilename(fileName, fileNameLen)) {
+            LOGW("Invalid filename (at %d)\n", i);
+            goto bail;
+        }
+
+#if SORT_ENTRIES
+        /* Figure out where this entry should go (binary search).
+         */
+        if (i > 0) {
+            int low, high;
+
+            low = 0;
+            high = i - 1;
+            while (low <= high) {
+                int mid;
+                int diff;
+                int diffLen;
+
+                mid = low + ((high - low) / 2); // avoid overflow
+
+                if (pArchive->pEntries[mid].fileNameLen < fileNameLen) {
+                    diffLen = pArchive->pEntries[mid].fileNameLen;
+                } else {
+                    diffLen = fileNameLen;
+                }
+                diff = strncmp(pArchive->pEntries[mid].fileName, fileName,
+                        diffLen);
+                if (diff == 0) {
+                    diff = pArchive->pEntries[mid].fileNameLen - fileNameLen;
+                }
+                if (diff < 0) {
+                    low = mid + 1;
+                } else if (diff > 0) {
+                    high = mid - 1;
+                } else {
+                    high = mid;
+                    break;
+                }
+            }
+
+            unsigned int target = high + 1;
+            assert(target <= i);
+            if (target != i) {
+                /* It belongs somewhere other than at the end of
+                 * the list.  Make some room at [target].
+                 */
+                memmove(pArchive->pEntries + target + 1,
+                        pArchive->pEntries + target,
+                        (i - target) * sizeof(ZipEntry));
+            }
+            pEntry = &pArchive->pEntries[target];
+        } else {
+            pEntry = &pArchive->pEntries[0];
+        }
+#else
+        pEntry = &pArchive->pEntries[i];
+#endif
+
+        //LOGI("%d: localHdr=%d fnl=%d el=%d cl=%d\n",
+        //    i, localHdrOffset, fileNameLen, extraLen, commentLen);
+
+        pEntry->fileNameLen = fileNameLen;
+        pEntry->fileName = fileName;
+
+        pEntry->compLen = get4LE(ptr + CENSIZ);
+        pEntry->uncompLen = get4LE(ptr + CENLEN);
+        pEntry->compression = get2LE(ptr + CENHOW);
+        pEntry->modTime = get4LE(ptr + CENTIM);
+        pEntry->crc32 = get4LE(ptr + CENCRC);
+
+        /* These two are necessary for finding the mode of the file.
+         */
+        pEntry->versionMadeBy = get2LE(ptr + CENVEM);
+        if ((pEntry->versionMadeBy & 0xff00) != 0 &&
+                (pEntry->versionMadeBy & 0xff00) != CENVEM_UNIX)
+        {
+            LOGW("Incompatible \"version made by\": 0x%02x (at %d)\n",
+                    pEntry->versionMadeBy >> 8, i);
+            goto bail;
+        }
+        pEntry->externalFileAttributes = get4LE(ptr + CENATX);
+
+        // Perform pMap->addr + localHdrOffset, ensuring that it won't
+        // overflow. This is needed because localHdrOffset is untrusted.
+        if (!safe_add((uintptr_t *)&localHdr, (uintptr_t)pMap->addr,
+            (uintptr_t)localHdrOffset)) {
+            LOGW("Integer overflow adding in parseZipArchive\n");
+            goto bail;
+        }
+        if ((uintptr_t)localHdr + LOCHDR >
+            (uintptr_t)pMap->addr + pMap->length) {
+            LOGW("Bad offset to local header: %d (at %d)\n", localHdrOffset, i);
+            goto bail;
+        }
+        if (get4LE(localHdr) != LOCSIG) {
+            LOGW("Missed a local header sig (at %d)\n", i);
+            goto bail;
+        }
+        pEntry->offset = localHdrOffset + LOCHDR
+            + get2LE(localHdr + LOCNAM) + get2LE(localHdr + LOCEXT);
+        if (!safe_add(NULL, pEntry->offset, pEntry->compLen)) {
+            LOGW("Integer overflow adding in parseZipArchive\n");
+            goto bail;
+        }
+        if ((size_t)pEntry->offset + pEntry->compLen > pMap->length) {
+            LOGW("Data ran off the end (at %d)\n", i);
+            goto bail;
+        }
+
+#if !SORT_ENTRIES
+        /* Add to hash table; no need to lock here.
+         * Can't do this now if we're sorting, because entries
+         * will move around.
+         */
+        addEntryToHashTable(pArchive->pHash, pEntry);
+#endif
+
+        //dumpEntry(pEntry);
+        ptr += CENHDR + fileNameLen + extraLen + commentLen;
+    }
+
+#if SORT_ENTRIES
+    /* If we're sorting, we have to wait until all entries
+     * are in their final places, otherwise the pointers will
+     * probably point to the wrong things.
+     */
+    for (i = 0; i < numEntries; i++) {
+        /* Add to hash table; no need to lock here.
+         */
+        addEntryToHashTable(pArchive->pHash, &pArchive->pEntries[i]);
+    }
+#endif
+
+    result = true;
+
+bail:
+    if (!result) {
+        mzHashTableFree(pArchive->pHash);
+        pArchive->pHash = NULL;
+    }
+    return result;
+}
+
+/*
+ * Open a Zip archive and scan out the contents.
+ *
+ * The easiest way to do this is to mmap() the whole thing and do the
+ * traditional backward scan for central directory.  Since the EOCD is
+ * a relatively small bit at the end, we should end up only touching a
+ * small set of pages.
+ *
+ * This will be called on non-Zip files, especially during startup, so
+ * we don't want to be too noisy about failures.  (Do we want a "quiet"
+ * flag?)
+ *
+ * On success, we fill out the contents of "pArchive".
+ */
+int mzOpenZipArchive(const char* fileName, ZipArchive* pArchive)
+{
+    MemMapping map;
+    int err;
+
+    LOGV("Opening archive '%s' %p\n", fileName, pArchive);
+
+    map.addr = NULL;
+    memset(pArchive, 0, sizeof(*pArchive));
+
+    pArchive->fd = open(fileName, O_RDONLY, 0);
+    if (pArchive->fd < 0) {
+        err = errno ? errno : -1;
+        LOGV("Unable to open '%s': %s\n", fileName, strerror(err));
+        goto bail;
+    }
+
+    if (sysMapFileInShmem(pArchive->fd, &map) != 0) {
+        err = -1;
+        LOGW("Map of '%s' failed\n", fileName);
+        goto bail;
+    }
+
+    if (map.length < ENDHDR) {
+        err = -1;
+        LOGV("File '%s' too small to be zip (%zd)\n", fileName, map.length);
+        goto bail;
+    }
+
+    if (!parseZipArchive(pArchive, &map)) {
+        err = -1;
+        LOGV("Parsing '%s' failed\n", fileName);
+        goto bail;
+    }
+
+    err = 0;
+    sysCopyMap(&pArchive->map, &map);
+    map.addr = NULL;
+
+bail:
+    if (err != 0)
+        mzCloseZipArchive(pArchive);
+    if (map.addr != NULL)
+        sysReleaseShmem(&map);
+    return err;
+}
+
+/*
+ * Close a ZipArchive, closing the file and freeing the contents.
+ *
+ * NOTE: the ZipArchive may not have been fully created.
+ */
+void mzCloseZipArchive(ZipArchive* pArchive)
+{
+    LOGV("Closing archive %p\n", pArchive);
+
+    if (pArchive->fd >= 0)
+        close(pArchive->fd);
+    if (pArchive->map.addr != NULL)
+        sysReleaseShmem(&pArchive->map);
+
+    free(pArchive->pEntries);
+
+    mzHashTableFree(pArchive->pHash);
+
+    pArchive->fd = -1;
+    pArchive->pHash = NULL;
+    pArchive->pEntries = NULL;
+}
+
+/*
+ * Find a matching entry.
+ *
+ * Returns NULL if no matching entry found.
+ */
+const ZipEntry* mzFindZipEntry(const ZipArchive* pArchive,
+        const char* entryName)
+{
+    unsigned int itemHash = computeHash(entryName, strlen(entryName));
+
+    return (const ZipEntry*)mzHashTableLookup(pArchive->pHash,
+                itemHash, (char*) entryName, hashcmpZipName, false);
+}
+
+/*
+ * Return true if the entry is a symbolic link.
+ */
+bool mzIsZipEntrySymlink(const ZipEntry* pEntry)
+{
+    if ((pEntry->versionMadeBy & 0xff00) == CENVEM_UNIX) {
+        return S_ISLNK(pEntry->externalFileAttributes >> 16);
+    }
+    return false;
+}
+
+/* Call processFunction on the uncompressed data of a STORED entry.
+ */
+static bool processStoredEntry(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, ProcessZipEntryContentsFunction processFunction,
+    void *cookie)
+{
+    size_t bytesLeft = pEntry->compLen;
+    while (bytesLeft > 0) {
+        unsigned char buf[32 * 1024];
+        ssize_t n;
+        size_t count;
+        bool ret;
+
+        count = bytesLeft;
+        if (count > sizeof(buf)) {
+            count = sizeof(buf);
+        }
+        n = read(pArchive->fd, buf, count);
+        if (n < 0 || (size_t)n != count) {
+            LOGE("Can't read %zu bytes from zip file: %ld\n", count, n);
+            return false;
+        }
+        ret = processFunction(buf, n, cookie);
+        if (!ret) {
+            return false;
+        }
+        bytesLeft -= count;
+    }
+    return true;
+}
+
+static bool processDeflatedEntry(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, ProcessZipEntryContentsFunction processFunction,
+    void *cookie)
+{
+    long result = -1;
+    unsigned char readBuf[32 * 1024];
+    unsigned char procBuf[32 * 1024];
+    z_stream zstream;
+    int zerr;
+    long compRemaining;
+
+    compRemaining = pEntry->compLen;
+
+    /*
+     * 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*) procBuf;
+    zstream.avail_out = sizeof(procBuf);
+    zstream.data_type = Z_UNKNOWN;
+
+    /*
+     * Use the undocumented "negative window bits" feature to tell zlib
+     * that there's no zlib header waiting for it.
+     */
+    zerr = inflateInit2(&zstream, -MAX_WBITS);
+    if (zerr != Z_OK) {
+        if (zerr == Z_VERSION_ERROR) {
+            LOGE("Installed zlib is not compatible with linked version (%s)\n",
+                ZLIB_VERSION);
+        } else {
+            LOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
+        }
+        goto bail;
+    }
+
+    /*
+     * Loop while we have data.
+     */
+    do {
+        /* read as much as we can */
+        if (zstream.avail_in == 0) {
+            long getSize = (compRemaining > (long)sizeof(readBuf)) ?
+                        (long)sizeof(readBuf) : compRemaining;
+            LOGVV("+++ reading %ld bytes (%ld left)\n",
+                getSize, compRemaining);
+
+            int cc = read(pArchive->fd, readBuf, getSize);
+            if (cc != (int) getSize) {
+                LOGW("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) {
+            LOGD("zlib inflate call failed (zerr=%d)\n", zerr);
+            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(procBuf)))
+        {
+            long procSize = zstream.next_out - procBuf;
+            LOGVV("+++ processing %d bytes\n", (int) procSize);
+            bool ret = processFunction(procBuf, procSize, cookie);
+            if (!ret) {
+                LOGW("Process function elected to fail (in inflate)\n");
+                goto z_bail;
+            }
+
+            zstream.next_out = procBuf;
+            zstream.avail_out = sizeof(procBuf);
+        }
+    } while (zerr == Z_OK);
+
+    assert(zerr == Z_STREAM_END);       /* other errors should've been caught */
+
+    // success!
+    result = zstream.total_out;
+
+z_bail:
+    inflateEnd(&zstream);        /* free up any allocated structures */
+
+bail:
+    if (result != pEntry->uncompLen) {
+        if (result != -1)        // error already shown?
+            LOGW("Size mismatch on inflated file (%ld vs %ld)\n",
+                result, pEntry->uncompLen);
+        return false;
+    }
+    return true;
+}
+
+/*
+ * Stream the uncompressed data through the supplied function,
+ * passing cookie to it each time it gets called.  processFunction
+ * may be called more than once.
+ *
+ * If processFunction returns false, the operation is abandoned and
+ * mzProcessZipEntryContents() immediately returns false.
+ *
+ * This is useful for calculating the hash of an entry's uncompressed contents.
+ */
+bool mzProcessZipEntryContents(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, ProcessZipEntryContentsFunction processFunction,
+    void *cookie)
+{
+    bool ret = false;
+    off_t oldOff;
+
+    /* save current offset */
+    oldOff = lseek(pArchive->fd, 0, SEEK_CUR);
+
+    /* Seek to the beginning of the entry's compressed data. */
+    lseek(pArchive->fd, pEntry->offset, SEEK_SET);
+
+    switch (pEntry->compression) {
+    case STORED:
+        ret = processStoredEntry(pArchive, pEntry, processFunction, cookie);
+        break;
+    case DEFLATED:
+        ret = processDeflatedEntry(pArchive, pEntry, processFunction, cookie);
+        break;
+    default:
+        LOGE("Unsupported compression type %d for entry '%s'\n",
+                pEntry->compression, pEntry->fileName);
+        break;
+    }
+
+    /* restore file offset */
+    lseek(pArchive->fd, oldOff, SEEK_SET);
+    return ret;
+}
+
+static bool crcProcessFunction(const unsigned char *data, int dataLen,
+        void *crc)
+{
+    *(unsigned long *)crc = crc32(*(unsigned long *)crc, data, dataLen);
+    return true;
+}
+
+/*
+ * Check the CRC on this entry; return true if it is correct.
+ * May do other internal checks as well.
+ */
+bool mzIsZipEntryIntact(const ZipArchive *pArchive, const ZipEntry *pEntry)
+{
+    unsigned long crc;
+    bool ret;
+
+    crc = crc32(0L, Z_NULL, 0);
+    ret = mzProcessZipEntryContents(pArchive, pEntry, crcProcessFunction,
+            (void *)&crc);
+    if (!ret) {
+        LOGE("Can't calculate CRC for entry\n");
+        return false;
+    }
+    if (crc != (unsigned long)pEntry->crc32) {
+        LOGW("CRC for entry %.*s (0x%08lx) != expected (0x%08lx)\n",
+                pEntry->fileNameLen, pEntry->fileName, crc, pEntry->crc32);
+        return false;
+    }
+    return true;
+}
+
+typedef struct {
+    char *buf;
+    int bufLen;
+} CopyProcessArgs;
+
+static bool copyProcessFunction(const unsigned char *data, int dataLen,
+        void *cookie)
+{
+    CopyProcessArgs *args = (CopyProcessArgs *)cookie;
+    if (dataLen <= args->bufLen) {
+        memcpy(args->buf, data, dataLen);
+        args->buf += dataLen;
+        args->bufLen -= dataLen;
+        return true;
+    }
+    return false;
+}
+
+/*
+ * Read an entry into a buffer allocated by the caller.
+ */
+bool mzReadZipEntry(const ZipArchive* pArchive, const ZipEntry* pEntry,
+        char *buf, int bufLen)
+{
+    CopyProcessArgs args;
+    bool ret;
+    
+    args.buf = buf;
+    args.bufLen = bufLen;
+    ret = mzProcessZipEntryContents(pArchive, pEntry, copyProcessFunction,
+            (void *)&args);
+    if (!ret) {
+        LOGE("Can't extract entry to buffer.\n");
+        return false;
+    }
+    return true;
+}
+
+static bool writeProcessFunction(const unsigned char *data, int dataLen,
+        void *fd)
+{
+    ssize_t n = write((int)fd, data, dataLen);
+    if (n != dataLen) {
+        LOGE("Can't write %d bytes (only %ld) from zip file: %s\n",
+                dataLen, n, strerror(errno));
+        return false;
+    }
+    return true;
+}
+
+/*
+ * Uncompress "pEntry" in "pArchive" to "fd" at the current offset.
+ */
+bool mzExtractZipEntryToFile(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, int fd)
+{
+    bool ret = mzProcessZipEntryContents(pArchive, pEntry, writeProcessFunction,
+            (void *)fd);
+    if (!ret) {
+        LOGE("Can't extract entry to file.\n");
+        return false;
+    }
+    return true;
+}
+
+/* Helper state to make path translation easier and less malloc-happy.
+ */
+typedef struct {
+    const char *targetDir;
+    const char *zipDir;
+    char *buf;
+    int targetDirLen;
+    int zipDirLen;
+    int bufLen;
+} MzPathHelper;
+
+/* Given the values of targetDir and zipDir in the helper,
+ * return the target filename of the provided entry.
+ * The helper must be initialized first.
+ */
+static const char *targetEntryPath(MzPathHelper *helper, ZipEntry *pEntry)
+{
+    int needLen;
+    bool firstTime = (helper->buf == NULL);
+
+    /* target file <-- targetDir + / + entry[zipDirLen:]
+     */
+    needLen = helper->targetDirLen + 1 +
+            pEntry->fileNameLen - helper->zipDirLen + 1;
+    if (needLen > helper->bufLen) {
+        char *newBuf;
+
+        needLen *= 2;
+        newBuf = (char *)realloc(helper->buf, needLen);
+        if (newBuf == NULL) {
+            return NULL;
+        }
+        helper->buf = newBuf;
+        helper->bufLen = needLen;
+    }
+
+    /* Every path will start with the target path and a slash.
+     */
+    if (firstTime) {
+        char *p = helper->buf;
+        memcpy(p, helper->targetDir, helper->targetDirLen);
+        p += helper->targetDirLen;
+        if (p == helper->buf || p[-1] != '/') {
+            helper->targetDirLen += 1;
+            *p++ = '/';
+        }
+    }
+
+    /* Replace the custom part of the path with the appropriate
+     * part of the entry's path.
+     */
+    char *epath = helper->buf + helper->targetDirLen;
+    memcpy(epath, pEntry->fileName + helper->zipDirLen,
+            pEntry->fileNameLen - helper->zipDirLen);
+    epath += pEntry->fileNameLen - helper->zipDirLen;
+    *epath = '\0';
+
+    return helper->buf;
+}
+
+/*
+ * Inflate all entries under zipDir to the directory specified by
+ * targetDir, which must exist and be a writable directory.
+ *
+ * The immediate children of zipDir will become the immediate
+ * children of targetDir; e.g., if the archive contains the entries
+ *
+ *     a/b/c/one
+ *     a/b/c/two
+ *     a/b/c/d/three
+ *
+ * and mzExtractRecursive(a, "a/b/c", "/tmp") is called, the resulting
+ * files will be
+ *
+ *     /tmp/one
+ *     /tmp/two
+ *     /tmp/d/three
+ *
+ * Returns true on success, false on failure.
+ */
+bool mzExtractRecursive(const ZipArchive *pArchive,
+                        const char *zipDir, const char *targetDir,
+                        int flags, const struct utimbuf *timestamp,
+                        void (*callback)(const char *fn, void *), void *cookie)
+{
+    if (zipDir[0] == '/') {
+        LOGE("mzExtractRecursive(): zipDir must be a relative path.\n");
+        return false;
+    }
+    if (targetDir[0] != '/') {
+        LOGE("mzExtractRecursive(): targetDir must be an absolute path.\n");
+        return false;
+    }
+
+    unsigned int zipDirLen;
+    char *zpath;
+
+    zipDirLen = strlen(zipDir);
+    zpath = (char *)malloc(zipDirLen + 2);
+    if (zpath == NULL) {
+        LOGE("Can't allocate %d bytes for zip path\n", zipDirLen + 2);
+        return false;
+    }
+    /* If zipDir is empty, we'll extract the entire zip file.
+     * Otherwise, canonicalize the path.
+     */
+    if (zipDirLen > 0) {
+        /* Make sure there's (hopefully, exactly one) slash at the
+         * end of the path.  This way we don't need to worry about
+         * accidentally extracting "one/twothree" when a path like
+         * "one/two" is specified.
+         */
+        memcpy(zpath, zipDir, zipDirLen);
+        if (zpath[zipDirLen-1] != '/') {
+            zpath[zipDirLen++] = '/';
+        }
+    }
+    zpath[zipDirLen] = '\0';
+
+    /* Set up the helper structure that we'll use to assemble paths.
+     */
+    MzPathHelper helper;
+    helper.targetDir = targetDir;
+    helper.targetDirLen = strlen(helper.targetDir);
+    helper.zipDir = zpath;
+    helper.zipDirLen = strlen(helper.zipDir);
+    helper.buf = NULL;
+    helper.bufLen = 0;
+
+    /* Walk through the entries and extract anything whose path begins
+     * with zpath.
+//TODO: since the entries are sorted, binary search for the first match
+//      and stop after the first non-match.
+     */
+    unsigned int i;
+    bool seenMatch = false;
+    int ok = true;
+    for (i = 0; i < pArchive->numEntries; i++) {
+        ZipEntry *pEntry = pArchive->pEntries + i;
+        if (pEntry->fileNameLen < zipDirLen) {
+//TODO: look out for a single empty directory entry that matches zpath, but
+//      missing the trailing slash.  Most zip files seem to include
+//      the trailing slash, but I think it's legal to leave it off.
+//      e.g., zpath "a/b/", entry "a/b", with no children of the entry.
+            /* No chance of matching.
+             */
+#if SORT_ENTRIES
+            if (seenMatch) {
+                /* Since the entries are sorted, we can give up
+                 * on the first mismatch after the first match.
+                 */
+                break;
+            }
+#endif
+            continue;
+        }
+        /* If zpath is empty, this strncmp() will match everything,
+         * which is what we want.
+         */
+        if (strncmp(pEntry->fileName, zpath, zipDirLen) != 0) {
+#if SORT_ENTRIES
+            if (seenMatch) {
+                /* Since the entries are sorted, we can give up
+                 * on the first mismatch after the first match.
+                 */
+                break;
+            }
+#endif
+            continue;
+        }
+        /* This entry begins with zipDir, so we'll extract it.
+         */
+        seenMatch = true;
+
+        /* Find the target location of the entry.
+         */
+        const char *targetFile = targetEntryPath(&helper, pEntry);
+        if (targetFile == NULL) {
+            LOGE("Can't assemble target path for \"%.*s\"\n",
+                    pEntry->fileNameLen, pEntry->fileName);
+            ok = false;
+            break;
+        }
+
+        /* With DRY_RUN set, invoke the callback but don't do anything else.
+         */
+        if (flags & MZ_EXTRACT_DRY_RUN) {
+            if (callback != NULL) callback(targetFile, cookie);
+            continue;
+        }
+
+        /* Create the file or directory.
+         */
+#define UNZIP_DIRMODE 0755
+#define UNZIP_FILEMODE 0644
+        if (pEntry->fileName[pEntry->fileNameLen-1] == '/') {
+            if (!(flags & MZ_EXTRACT_FILES_ONLY)) {
+                int ret = dirCreateHierarchy(
+                        targetFile, UNZIP_DIRMODE, timestamp, false);
+                if (ret != 0) {
+                    LOGE("Can't create containing directory for \"%s\": %s\n",
+                            targetFile, strerror(errno));
+                    ok = false;
+                    break;
+                }
+                LOGD("Extracted dir \"%s\"\n", targetFile);
+            }
+        } else {
+            /* This is not a directory.  First, make sure that
+             * the containing directory exists.
+             */
+            int ret = dirCreateHierarchy(
+                    targetFile, UNZIP_DIRMODE, timestamp, true);
+            if (ret != 0) {
+                LOGE("Can't create containing directory for \"%s\": %s\n",
+                        targetFile, strerror(errno));
+                ok = false;
+                break;
+            }
+
+            /* With FILES_ONLY set, we need to ignore metadata entirely,
+             * so treat symlinks as regular files.
+             */
+            if (!(flags & MZ_EXTRACT_FILES_ONLY) && mzIsZipEntrySymlink(pEntry)) {
+                /* The entry is a symbolic link.
+                 * The relative target of the symlink is in the
+                 * data section of this entry.
+                 */
+                if (pEntry->uncompLen == 0) {
+                    LOGE("Symlink entry \"%s\" has no target\n",
+                            targetFile);
+                    ok = false;
+                    break;
+                }
+                char *linkTarget = malloc(pEntry->uncompLen + 1);
+                if (linkTarget == NULL) {
+                    ok = false;
+                    break;
+                }
+                ok = mzReadZipEntry(pArchive, pEntry, linkTarget,
+                        pEntry->uncompLen);
+                if (!ok) {
+                    LOGE("Can't read symlink target for \"%s\"\n",
+                            targetFile);
+                    free(linkTarget);
+                    break;
+                }
+                linkTarget[pEntry->uncompLen] = '\0';
+
+                /* Make the link.
+                 */
+                ret = symlink(linkTarget, targetFile);
+                if (ret != 0) {
+                    LOGE("Can't symlink \"%s\" to \"%s\": %s\n",
+                            targetFile, linkTarget, strerror(errno));
+                    free(linkTarget);
+                    ok = false;
+                    break;
+                }
+                LOGD("Extracted symlink \"%s\" -> \"%s\"\n",
+                        targetFile, linkTarget);
+                free(linkTarget);
+            } else {
+                /* The entry is a regular file.
+                 * Open the target for writing.
+                 */
+                int fd = creat(targetFile, UNZIP_FILEMODE);
+                if (fd < 0) {
+                    LOGE("Can't create target file \"%s\": %s\n",
+                            targetFile, strerror(errno));
+                    ok = false;
+                    break;
+                }
+
+                bool ok = mzExtractZipEntryToFile(pArchive, pEntry, fd);
+                close(fd);
+                if (!ok) {
+                    LOGE("Error extracting \"%s\"\n", targetFile);
+                    ok = false;
+                    break;
+                }
+
+                if (timestamp != NULL && utime(targetFile, timestamp)) {
+                    LOGE("Error touching \"%s\"\n", targetFile);
+                    ok = false;
+                    break;
+                }
+
+                LOGD("Extracted file \"%s\"\n", targetFile);
+            }
+        }
+
+        if (callback != NULL) callback(targetFile, cookie);
+    }
+
+    free(helper.buf);
+    free(zpath);
+
+    return ok;
+}