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      1 /*
      2  * Copyright (C) 2008 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 // This file is a nearly line-for-line copy of bspatch.c from the
     18 // bsdiff-4.3 distribution; the primary differences being how the
     19 // input and output data are read and the error handling.  Running
     20 // applypatch with the -l option will display the bsdiff license
     21 // notice.
     22 
     23 #include <stdio.h>
     24 #include <sys/stat.h>
     25 #include <sys/types.h>
     26 #include <errno.h>
     27 #include <unistd.h>
     28 #include <string.h>
     29 
     30 #include <bzlib.h>
     31 
     32 #include "openssl/sha.h"
     33 #include "applypatch.h"
     34 
     35 void ShowBSDiffLicense() {
     36     puts("The bsdiff library used herein is:\n"
     37          "\n"
     38          "Copyright 2003-2005 Colin Percival\n"
     39          "All rights reserved\n"
     40          "\n"
     41          "Redistribution and use in source and binary forms, with or without\n"
     42          "modification, are permitted providing that the following conditions\n"
     43          "are met:\n"
     44          "1. Redistributions of source code must retain the above copyright\n"
     45          "   notice, this list of conditions and the following disclaimer.\n"
     46          "2. Redistributions in binary form must reproduce the above copyright\n"
     47          "   notice, this list of conditions and the following disclaimer in the\n"
     48          "   documentation and/or other materials provided with the distribution.\n"
     49          "\n"
     50          "THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR\n"
     51          "IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\n"
     52          "WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE\n"
     53          "ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY\n"
     54          "DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL\n"
     55          "DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS\n"
     56          "OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)\n"
     57          "HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,\n"
     58          "STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING\n"
     59          "IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE\n"
     60          "POSSIBILITY OF SUCH DAMAGE.\n"
     61          "\n------------------\n\n"
     62          "This program uses Julian R Seward's \"libbzip2\" library, available\n"
     63          "from http://www.bzip.org/.\n"
     64         );
     65 }
     66 
     67 static off_t offtin(u_char *buf)
     68 {
     69     off_t y;
     70 
     71     y=buf[7]&0x7F;
     72     y=y*256;y+=buf[6];
     73     y=y*256;y+=buf[5];
     74     y=y*256;y+=buf[4];
     75     y=y*256;y+=buf[3];
     76     y=y*256;y+=buf[2];
     77     y=y*256;y+=buf[1];
     78     y=y*256;y+=buf[0];
     79 
     80     if(buf[7]&0x80) y=-y;
     81 
     82     return y;
     83 }
     84 
     85 int FillBuffer(unsigned char* buffer, int size, bz_stream* stream) {
     86     stream->next_out = (char*)buffer;
     87     stream->avail_out = size;
     88     while (stream->avail_out > 0) {
     89         int bzerr = BZ2_bzDecompress(stream);
     90         if (bzerr != BZ_OK && bzerr != BZ_STREAM_END) {
     91             printf("bz error %d decompressing\n", bzerr);
     92             return -1;
     93         }
     94         if (stream->avail_out > 0) {
     95             printf("need %d more bytes\n", stream->avail_out);
     96         }
     97     }
     98     return 0;
     99 }
    100 
    101 int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
    102                      const Value* patch, ssize_t patch_offset,
    103                      SinkFn sink, void* token, SHA_CTX* ctx) {
    104 
    105     std::vector<unsigned char> new_data;
    106     if (ApplyBSDiffPatchMem(old_data, old_size, patch, patch_offset, &new_data) != 0) {
    107         return -1;
    108     }
    109 
    110     if (sink(new_data.data(), new_data.size(), token) < static_cast<ssize_t>(new_data.size())) {
    111         printf("short write of output: %d (%s)\n", errno, strerror(errno));
    112         return 1;
    113     }
    114     if (ctx) SHA1_Update(ctx, new_data.data(), new_data.size());
    115     return 0;
    116 }
    117 
    118 int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
    119                         const Value* patch, ssize_t patch_offset,
    120                         std::vector<unsigned char>* new_data) {
    121     // Patch data format:
    122     //   0       8       "BSDIFF40"
    123     //   8       8       X
    124     //   16      8       Y
    125     //   24      8       sizeof(newfile)
    126     //   32      X       bzip2(control block)
    127     //   32+X    Y       bzip2(diff block)
    128     //   32+X+Y  ???     bzip2(extra block)
    129     // with control block a set of triples (x,y,z) meaning "add x bytes
    130     // from oldfile to x bytes from the diff block; copy y bytes from the
    131     // extra block; seek forwards in oldfile by z bytes".
    132 
    133     unsigned char* header = (unsigned char*) patch->data + patch_offset;
    134     if (memcmp(header, "BSDIFF40", 8) != 0) {
    135         printf("corrupt bsdiff patch file header (magic number)\n");
    136         return 1;
    137     }
    138 
    139     ssize_t ctrl_len, data_len, new_size;
    140     ctrl_len = offtin(header+8);
    141     data_len = offtin(header+16);
    142     new_size = offtin(header+24);
    143 
    144     if (ctrl_len < 0 || data_len < 0 || new_size < 0) {
    145         printf("corrupt patch file header (data lengths)\n");
    146         return 1;
    147     }
    148 
    149     int bzerr;
    150 
    151     bz_stream cstream;
    152     cstream.next_in = patch->data + patch_offset + 32;
    153     cstream.avail_in = ctrl_len;
    154     cstream.bzalloc = NULL;
    155     cstream.bzfree = NULL;
    156     cstream.opaque = NULL;
    157     if ((bzerr = BZ2_bzDecompressInit(&cstream, 0, 0)) != BZ_OK) {
    158         printf("failed to bzinit control stream (%d)\n", bzerr);
    159     }
    160 
    161     bz_stream dstream;
    162     dstream.next_in = patch->data + patch_offset + 32 + ctrl_len;
    163     dstream.avail_in = data_len;
    164     dstream.bzalloc = NULL;
    165     dstream.bzfree = NULL;
    166     dstream.opaque = NULL;
    167     if ((bzerr = BZ2_bzDecompressInit(&dstream, 0, 0)) != BZ_OK) {
    168         printf("failed to bzinit diff stream (%d)\n", bzerr);
    169     }
    170 
    171     bz_stream estream;
    172     estream.next_in = patch->data + patch_offset + 32 + ctrl_len + data_len;
    173     estream.avail_in = patch->size - (patch_offset + 32 + ctrl_len + data_len);
    174     estream.bzalloc = NULL;
    175     estream.bzfree = NULL;
    176     estream.opaque = NULL;
    177     if ((bzerr = BZ2_bzDecompressInit(&estream, 0, 0)) != BZ_OK) {
    178         printf("failed to bzinit extra stream (%d)\n", bzerr);
    179     }
    180 
    181     new_data->resize(new_size);
    182 
    183     off_t oldpos = 0, newpos = 0;
    184     off_t ctrl[3];
    185     off_t len_read;
    186     int i;
    187     unsigned char buf[24];
    188     while (newpos < new_size) {
    189         // Read control data
    190         if (FillBuffer(buf, 24, &cstream) != 0) {
    191             printf("error while reading control stream\n");
    192             return 1;
    193         }
    194         ctrl[0] = offtin(buf);
    195         ctrl[1] = offtin(buf+8);
    196         ctrl[2] = offtin(buf+16);
    197 
    198         if (ctrl[0] < 0 || ctrl[1] < 0) {
    199             printf("corrupt patch (negative byte counts)\n");
    200             return 1;
    201         }
    202 
    203         // Sanity check
    204         if (newpos + ctrl[0] > new_size) {
    205             printf("corrupt patch (new file overrun)\n");
    206             return 1;
    207         }
    208 
    209         // Read diff string
    210         if (FillBuffer(new_data->data() + newpos, ctrl[0], &dstream) != 0) {
    211             printf("error while reading diff stream\n");
    212             return 1;
    213         }
    214 
    215         // Add old data to diff string
    216         for (i = 0; i < ctrl[0]; ++i) {
    217             if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
    218                 (*new_data)[newpos+i] += old_data[oldpos+i];
    219             }
    220         }
    221 
    222         // Adjust pointers
    223         newpos += ctrl[0];
    224         oldpos += ctrl[0];
    225 
    226         // Sanity check
    227         if (newpos + ctrl[1] > new_size) {
    228             printf("corrupt patch (new file overrun)\n");
    229             return 1;
    230         }
    231 
    232         // Read extra string
    233         if (FillBuffer(new_data->data() + newpos, ctrl[1], &estream) != 0) {
    234             printf("error while reading extra stream\n");
    235             return 1;
    236         }
    237 
    238         // Adjust pointers
    239         newpos += ctrl[1];
    240         oldpos += ctrl[2];
    241     }
    242 
    243     BZ2_bzDecompressEnd(&cstream);
    244     BZ2_bzDecompressEnd(&dstream);
    245     BZ2_bzDecompressEnd(&estream);
    246     return 0;
    247 }
    248