summaryrefslogblamecommitdiffstats
path: root/minzip/Zip.c
blob: ead89939004bd57f1447bd368e4570ba57887f41 (plain) (tree)
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759










































                                                                 
                























                                     
 




                
                











































































































































































































































































































































































































































































































































































































































































































                                                                                
 













                                                                          






















                                                                   




























































































































































































































































































































                                                                                  
/*
 * 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)
{
    int zeroWrites = 0;
    ssize_t soFar = 0;
    do {
        ssize_t n = write((int)fd, data+soFar, dataLen-soFar);
        if (n < 0) {
            LOGE("Error writing %ld bytes from zip file: %s\n",
                 dataLen-soFar, strerror(errno));
            return false;
        } else if (n > 0) {
            soFar += n;
            if (soFar == dataLen) return true;
            if (soFar > dataLen) {
                LOGE("write overrun?  (%ld bytes instead of %d)\n",
                     soFar, dataLen);
                return false;
            }
            zeroWrites = 0;
        } else {
            ++zeroWrites;
        }
    } while (zeroWrites < 5);
    LOGE("too many consecutive zero-length writes\n");
    return false;
}

/*
 * 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;
}