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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 //
     18 // Misc zip/gzip utility functions.
     19 //
     20 
     21 #define LOG_TAG "ziputil"
     22 
     23 #include <androidfw/ZipUtils.h>
     24 #include <androidfw/ZipFileRO.h>
     25 #include <utils/Log.h>
     26 #include <utils/Compat.h>
     27 
     28 #include <stdlib.h>
     29 #include <string.h>
     30 #include <assert.h>
     31 
     32 #include <zlib.h>
     33 
     34 using namespace android;
     35 
     36 /*
     37  * Utility function that expands zip/gzip "deflate" compressed data
     38  * into a buffer.
     39  *
     40  * "fd" is an open file positioned at the start of the "deflate" data
     41  * "buf" must hold at least "uncompressedLen" bytes.
     42  */
     43 /*static*/ bool ZipUtils::inflateToBuffer(int fd, void* buf,
     44     long uncompressedLen, long compressedLen)
     45 {
     46     bool result = false;
     47 	const unsigned long kReadBufSize = 32768;
     48 	unsigned char* readBuf = NULL;
     49     z_stream zstream;
     50     int zerr;
     51     unsigned long compRemaining;
     52 
     53     assert(uncompressedLen >= 0);
     54     assert(compressedLen >= 0);
     55 
     56 	readBuf = new unsigned char[kReadBufSize];
     57 	if (readBuf == NULL)
     58         goto bail;
     59     compRemaining = compressedLen;
     60 
     61     /*
     62      * Initialize the zlib stream.
     63      */
     64 	memset(&zstream, 0, sizeof(zstream));
     65     zstream.zalloc = Z_NULL;
     66     zstream.zfree = Z_NULL;
     67     zstream.opaque = Z_NULL;
     68     zstream.next_in = NULL;
     69     zstream.avail_in = 0;
     70     zstream.next_out = (Bytef*) buf;
     71     zstream.avail_out = uncompressedLen;
     72     zstream.data_type = Z_UNKNOWN;
     73 
     74 	/*
     75 	 * Use the undocumented "negative window bits" feature to tell zlib
     76 	 * that there's no zlib header waiting for it.
     77 	 */
     78     zerr = inflateInit2(&zstream, -MAX_WBITS);
     79     if (zerr != Z_OK) {
     80         if (zerr == Z_VERSION_ERROR) {
     81             ALOGE("Installed zlib is not compatible with linked version (%s)\n",
     82                 ZLIB_VERSION);
     83         } else {
     84             ALOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
     85         }
     86         goto bail;
     87     }
     88 
     89     /*
     90      * Loop while we have data.
     91      */
     92     do {
     93         unsigned long getSize;
     94 
     95         /* read as much as we can */
     96         if (zstream.avail_in == 0) {
     97             getSize = (compRemaining > kReadBufSize) ?
     98                         kReadBufSize : compRemaining;
     99             ALOGV("+++ reading %ld bytes (%ld left)\n",
    100                 getSize, compRemaining);
    101 
    102             int cc = TEMP_FAILURE_RETRY(read(fd, readBuf, getSize));
    103             if (cc < 0) {
    104                 ALOGW("inflate read failed: %s", strerror(errno));
    105             } else if (cc != (int) getSize) {
    106                 ALOGW("inflate read failed (%d vs %ld)", cc, getSize);
    107                 goto z_bail;
    108             }
    109 
    110             compRemaining -= getSize;
    111 
    112             zstream.next_in = readBuf;
    113             zstream.avail_in = getSize;
    114         }
    115 
    116         /* uncompress the data */
    117         zerr = inflate(&zstream, Z_NO_FLUSH);
    118         if (zerr != Z_OK && zerr != Z_STREAM_END) {
    119             ALOGD("zlib inflate call failed (zerr=%d)\n", zerr);
    120             goto z_bail;
    121         }
    122 
    123 		/* output buffer holds all, so no need to write the output */
    124     } while (zerr == Z_OK);
    125 
    126     assert(zerr == Z_STREAM_END);       /* other errors should've been caught */
    127 
    128     if ((long) zstream.total_out != uncompressedLen) {
    129         ALOGW("Size mismatch on inflated file (%ld vs %ld)\n",
    130             zstream.total_out, uncompressedLen);
    131         goto z_bail;
    132     }
    133 
    134     // success!
    135     result = true;
    136 
    137 z_bail:
    138     inflateEnd(&zstream);        /* free up any allocated structures */
    139 
    140 bail:
    141 	delete[] readBuf;
    142     return result;
    143 }
    144 
    145 /*
    146  * Utility function that expands zip/gzip "deflate" compressed data
    147  * into a buffer.
    148  *
    149  * (This is a clone of the previous function, but it takes a FILE* instead
    150  * of an fd.  We could pass fileno(fd) to the above, but we can run into
    151  * trouble when "fp" has a different notion of what fd's file position is.)
    152  *
    153  * "fp" is an open file positioned at the start of the "deflate" data
    154  * "buf" must hold at least "uncompressedLen" bytes.
    155  */
    156 /*static*/ bool ZipUtils::inflateToBuffer(FILE* fp, void* buf,
    157     long uncompressedLen, long compressedLen)
    158 {
    159     bool result = false;
    160 	const unsigned long kReadBufSize = 32768;
    161 	unsigned char* readBuf = NULL;
    162     z_stream zstream;
    163     int zerr;
    164     unsigned long compRemaining;
    165 
    166     assert(uncompressedLen >= 0);
    167     assert(compressedLen >= 0);
    168 
    169 	readBuf = new unsigned char[kReadBufSize];
    170 	if (readBuf == NULL)
    171         goto bail;
    172     compRemaining = compressedLen;
    173 
    174     /*
    175      * Initialize the zlib stream.
    176      */
    177 	memset(&zstream, 0, sizeof(zstream));
    178     zstream.zalloc = Z_NULL;
    179     zstream.zfree = Z_NULL;
    180     zstream.opaque = Z_NULL;
    181     zstream.next_in = NULL;
    182     zstream.avail_in = 0;
    183     zstream.next_out = (Bytef*) buf;
    184     zstream.avail_out = uncompressedLen;
    185     zstream.data_type = Z_UNKNOWN;
    186 
    187 	/*
    188 	 * Use the undocumented "negative window bits" feature to tell zlib
    189 	 * that there's no zlib header waiting for it.
    190 	 */
    191     zerr = inflateInit2(&zstream, -MAX_WBITS);
    192     if (zerr != Z_OK) {
    193         if (zerr == Z_VERSION_ERROR) {
    194             ALOGE("Installed zlib is not compatible with linked version (%s)\n",
    195                 ZLIB_VERSION);
    196         } else {
    197             ALOGE("Call to inflateInit2 failed (zerr=%d)\n", zerr);
    198         }
    199         goto bail;
    200     }
    201 
    202     /*
    203      * Loop while we have data.
    204      */
    205     do {
    206         unsigned long getSize;
    207 
    208         /* read as much as we can */
    209         if (zstream.avail_in == 0) {
    210             getSize = (compRemaining > kReadBufSize) ?
    211                         kReadBufSize : compRemaining;
    212             ALOGV("+++ reading %ld bytes (%ld left)\n",
    213                 getSize, compRemaining);
    214 
    215             int cc = fread(readBuf, 1, getSize, fp);
    216             if (cc != (int) getSize) {
    217                 ALOGD("inflate read failed (%d vs %ld)\n",
    218                     cc, getSize);
    219                 goto z_bail;
    220             }
    221 
    222             compRemaining -= getSize;
    223 
    224             zstream.next_in = readBuf;
    225             zstream.avail_in = getSize;
    226         }
    227 
    228         /* uncompress the data */
    229         zerr = inflate(&zstream, Z_NO_FLUSH);
    230         if (zerr != Z_OK && zerr != Z_STREAM_END) {
    231             ALOGD("zlib inflate call failed (zerr=%d)\n", zerr);
    232             goto z_bail;
    233         }
    234 
    235 		/* output buffer holds all, so no need to write the output */
    236     } while (zerr == Z_OK);
    237 
    238     assert(zerr == Z_STREAM_END);       /* other errors should've been caught */
    239 
    240     if ((long) zstream.total_out != uncompressedLen) {
    241         ALOGW("Size mismatch on inflated file (%ld vs %ld)\n",
    242             zstream.total_out, uncompressedLen);
    243         goto z_bail;
    244     }
    245 
    246     // success!
    247     result = true;
    248 
    249 z_bail:
    250     inflateEnd(&zstream);        /* free up any allocated structures */
    251 
    252 bail:
    253 	delete[] readBuf;
    254     return result;
    255 }
    256 
    257 /*
    258  * Look at the contents of a gzip archive.  We want to know where the
    259  * data starts, and how long it will be after it is uncompressed.
    260  *
    261  * We expect to find the CRC and length as the last 8 bytes on the file.
    262  * This is a pretty reasonable thing to expect for locally-compressed
    263  * files, but there's a small chance that some extra padding got thrown
    264  * on (the man page talks about compressed data written to tape).  We
    265  * don't currently deal with that here.  If "gzip -l" whines, we're going
    266  * to fail too.
    267  *
    268  * On exit, "fp" is pointing at the start of the compressed data.
    269  */
    270 /*static*/ bool ZipUtils::examineGzip(FILE* fp, int* pCompressionMethod,
    271     long* pUncompressedLen, long* pCompressedLen, unsigned long* pCRC32)
    272 {
    273     enum {  // flags
    274         FTEXT       = 0x01,
    275         FHCRC       = 0x02,
    276         FEXTRA      = 0x04,
    277         FNAME       = 0x08,
    278         FCOMMENT    = 0x10,
    279     };
    280     int ic;
    281     int method, flags;
    282     int i;
    283 
    284     ic = getc(fp);
    285     if (ic != 0x1f || getc(fp) != 0x8b)
    286         return false;       // not gzip
    287     method = getc(fp);
    288     flags = getc(fp);
    289 
    290     /* quick sanity checks */
    291     if (method == EOF || flags == EOF)
    292         return false;
    293     if (method != ZipFileRO::kCompressDeflated)
    294         return false;
    295 
    296     /* skip over 4 bytes of mod time, 1 byte XFL, 1 byte OS */
    297     for (i = 0; i < 6; i++)
    298         (void) getc(fp);
    299     /* consume "extra" field, if present */
    300     if ((flags & FEXTRA) != 0) {
    301         int len;
    302 
    303         len = getc(fp);
    304         len |= getc(fp) << 8;
    305         while (len-- && getc(fp) != EOF)
    306             ;
    307     }
    308     /* consume filename, if present */
    309     if ((flags & FNAME) != 0) {
    310         do {
    311             ic = getc(fp);
    312         } while (ic != 0 && ic != EOF);
    313     }
    314     /* consume comment, if present */
    315     if ((flags & FCOMMENT) != 0) {
    316         do {
    317             ic = getc(fp);
    318         } while (ic != 0 && ic != EOF);
    319     }
    320     /* consume 16-bit header CRC, if present */
    321     if ((flags & FHCRC) != 0) {
    322         (void) getc(fp);
    323         (void) getc(fp);
    324     }
    325 
    326     if (feof(fp) || ferror(fp))
    327         return false;
    328 
    329     /* seek to the end; CRC and length are in the last 8 bytes */
    330     long curPosn = ftell(fp);
    331     unsigned char buf[8];
    332     fseek(fp, -8, SEEK_END);
    333     *pCompressedLen = ftell(fp) - curPosn;
    334 
    335     if (fread(buf, 1, 8, fp) != 8)
    336         return false;
    337     /* seek back to start of compressed data */
    338     fseek(fp, curPosn, SEEK_SET);
    339 
    340     *pCompressionMethod = method;
    341     *pCRC32 = ZipFileRO::get4LE(&buf[0]);
    342     *pUncompressedLen = ZipFileRO::get4LE(&buf[4]);
    343 
    344     return true;
    345 }
    346