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 <errno.h>
26#include <unistd.h>
27#include <string.h>
28
29#include <bzlib.h>
30
31#include "mincrypt/sha.h"
32#include "applypatch.h"
33
34void ShowBSDiffLicense() {
35    puts("The bsdiff library used herein is:\n"
36         "\n"
37         "Copyright 2003-2005 Colin Percival\n"
38         "All rights reserved\n"
39         "\n"
40         "Redistribution and use in source and binary forms, with or without\n"
41         "modification, are permitted providing that the following conditions\n"
42         "are met:\n"
43         "1. Redistributions of source code must retain the above copyright\n"
44         "   notice, this list of conditions and the following disclaimer.\n"
45         "2. Redistributions in binary form must reproduce the above copyright\n"
46         "   notice, this list of conditions and the following disclaimer in the\n"
47         "   documentation and/or other materials provided with the distribution.\n"
48         "\n"
49         "THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR\n"
50         "IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\n"
51         "WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE\n"
52         "ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY\n"
53         "DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL\n"
54         "DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS\n"
55         "OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)\n"
56         "HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,\n"
57         "STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING\n"
58         "IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE\n"
59         "POSSIBILITY OF SUCH DAMAGE.\n"
60         "\n------------------\n\n"
61         "This program uses Julian R Seward's \"libbzip2\" library, available\n"
62         "from http://www.bzip.org/.\n"
63        );
64}
65
66static off_t offtin(u_char *buf)
67{
68    off_t y;
69
70    y=buf[7]&0x7F;
71    y=y*256;y+=buf[6];
72    y=y*256;y+=buf[5];
73    y=y*256;y+=buf[4];
74    y=y*256;y+=buf[3];
75    y=y*256;y+=buf[2];
76    y=y*256;y+=buf[1];
77    y=y*256;y+=buf[0];
78
79    if(buf[7]&0x80) y=-y;
80
81    return y;
82}
83
84int FillBuffer(unsigned char* buffer, int size, bz_stream* stream) {
85    stream->next_out = (char*)buffer;
86    stream->avail_out = size;
87    while (stream->avail_out > 0) {
88        int bzerr = BZ2_bzDecompress(stream);
89        if (bzerr != BZ_OK && bzerr != BZ_STREAM_END) {
90            printf("bz error %d decompressing\n", bzerr);
91            return -1;
92        }
93        if (stream->avail_out > 0) {
94            printf("need %d more bytes\n", stream->avail_out);
95        }
96    }
97    return 0;
98}
99
100int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
101                     const Value* patch, ssize_t patch_offset,
102                     SinkFn sink, void* token, SHA_CTX* ctx) {
103
104    unsigned char* new_data;
105    ssize_t new_size;
106    if (ApplyBSDiffPatchMem(old_data, old_size, patch, patch_offset,
107                            &new_data, &new_size) != 0) {
108        return -1;
109    }
110
111    if (sink(new_data, new_size, token) < new_size) {
112        printf("short write of output: %d (%s)\n", errno, strerror(errno));
113        return 1;
114    }
115    if (ctx) SHA_update(ctx, new_data, new_size);
116    free(new_data);
117
118    return 0;
119}
120
121int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
122                        const Value* patch, ssize_t patch_offset,
123                        unsigned char** new_data, ssize_t* new_size) {
124    // Patch data format:
125    //   0       8       "BSDIFF40"
126    //   8       8       X
127    //   16      8       Y
128    //   24      8       sizeof(newfile)
129    //   32      X       bzip2(control block)
130    //   32+X    Y       bzip2(diff block)
131    //   32+X+Y  ???     bzip2(extra block)
132    // with control block a set of triples (x,y,z) meaning "add x bytes
133    // from oldfile to x bytes from the diff block; copy y bytes from the
134    // extra block; seek forwards in oldfile by z bytes".
135
136    unsigned char* header = (unsigned char*) patch->data + patch_offset;
137    if (memcmp(header, "BSDIFF40", 8) != 0) {
138        printf("corrupt bsdiff patch file header (magic number)\n");
139        return 1;
140    }
141
142    ssize_t ctrl_len, data_len;
143    ctrl_len = offtin(header+8);
144    data_len = offtin(header+16);
145    *new_size = offtin(header+24);
146
147    if (ctrl_len < 0 || data_len < 0 || *new_size < 0) {
148        printf("corrupt patch file header (data lengths)\n");
149        return 1;
150    }
151
152    int bzerr;
153
154    bz_stream cstream;
155    cstream.next_in = patch->data + patch_offset + 32;
156    cstream.avail_in = ctrl_len;
157    cstream.bzalloc = NULL;
158    cstream.bzfree = NULL;
159    cstream.opaque = NULL;
160    if ((bzerr = BZ2_bzDecompressInit(&cstream, 0, 0)) != BZ_OK) {
161        printf("failed to bzinit control stream (%d)\n", bzerr);
162    }
163
164    bz_stream dstream;
165    dstream.next_in = patch->data + patch_offset + 32 + ctrl_len;
166    dstream.avail_in = data_len;
167    dstream.bzalloc = NULL;
168    dstream.bzfree = NULL;
169    dstream.opaque = NULL;
170    if ((bzerr = BZ2_bzDecompressInit(&dstream, 0, 0)) != BZ_OK) {
171        printf("failed to bzinit diff stream (%d)\n", bzerr);
172    }
173
174    bz_stream estream;
175    estream.next_in = patch->data + patch_offset + 32 + ctrl_len + data_len;
176    estream.avail_in = patch->size - (patch_offset + 32 + ctrl_len + data_len);
177    estream.bzalloc = NULL;
178    estream.bzfree = NULL;
179    estream.opaque = NULL;
180    if ((bzerr = BZ2_bzDecompressInit(&estream, 0, 0)) != BZ_OK) {
181        printf("failed to bzinit extra stream (%d)\n", bzerr);
182    }
183
184    *new_data = malloc(*new_size);
185    if (*new_data == NULL) {
186        printf("failed to allocate %ld bytes of memory for output file\n",
187               (long)*new_size);
188        return 1;
189    }
190
191    off_t oldpos = 0, newpos = 0;
192    off_t ctrl[3];
193    off_t len_read;
194    int i;
195    unsigned char buf[24];
196    while (newpos < *new_size) {
197        // Read control data
198        if (FillBuffer(buf, 24, &cstream) != 0) {
199            printf("error while reading control stream\n");
200            return 1;
201        }
202        ctrl[0] = offtin(buf);
203        ctrl[1] = offtin(buf+8);
204        ctrl[2] = offtin(buf+16);
205
206        if (ctrl[0] < 0 || ctrl[1] < 0) {
207            printf("corrupt patch (negative byte counts)\n");
208            return 1;
209        }
210
211        // Sanity check
212        if (newpos + ctrl[0] > *new_size) {
213            printf("corrupt patch (new file overrun)\n");
214            return 1;
215        }
216
217        // Read diff string
218        if (FillBuffer(*new_data + newpos, ctrl[0], &dstream) != 0) {
219            printf("error while reading diff stream\n");
220            return 1;
221        }
222
223        // Add old data to diff string
224        for (i = 0; i < ctrl[0]; ++i) {
225            if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
226                (*new_data)[newpos+i] += old_data[oldpos+i];
227            }
228        }
229
230        // Adjust pointers
231        newpos += ctrl[0];
232        oldpos += ctrl[0];
233
234        // Sanity check
235        if (newpos + ctrl[1] > *new_size) {
236            printf("corrupt patch (new file overrun)\n");
237            return 1;
238        }
239
240        // Read extra string
241        if (FillBuffer(*new_data + newpos, ctrl[1], &estream) != 0) {
242            printf("error while reading extra stream\n");
243            return 1;
244        }
245
246        // Adjust pointers
247        newpos += ctrl[1];
248        oldpos += ctrl[2];
249    }
250
251    BZ2_bzDecompressEnd(&cstream);
252    BZ2_bzDecompressEnd(&dstream);
253    BZ2_bzDecompressEnd(&estream);
254    return 0;
255}
256