1 /*-
2 * Copyright 2003-2005 Colin Percival
3 * All rights reserved
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted providing that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
22 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
23 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24 * POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #if 0
28 __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bsdiff/bsdiff.c,v 1.1 2005/08/06 01:59:05 cperciva Exp $");
29 #endif
30
31 #include <sys/types.h>
32
33 #include <bzlib.h>
34 #include <err.h>
35 #include <fcntl.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <unistd.h>
40
41 #include <algorithm>
42
43 #if _FILE_OFFSET_BITS == 64
44 #include "divsufsort64.h"
45 #define saidx_t saidx64_t
46 #define divsufsort divsufsort64
47 #else
48 #include "divsufsort.h"
49 #endif
50
51 namespace bsdiff {
52
matchlen(u_char * old,off_t oldsize,u_char * new_buf,off_t newsize)53 static off_t matchlen(u_char *old, off_t oldsize, u_char *new_buf,
54 off_t newsize) {
55 off_t i;
56
57 for(i=0;(i<oldsize)&&(i<newsize);i++)
58 if(old[i]!=new_buf[i]) break;
59
60 return i;
61 }
62
search(saidx_t * I,u_char * old,off_t oldsize,u_char * new_buf,off_t newsize,off_t st,off_t en,off_t * pos)63 static off_t search(saidx_t *I,u_char *old,off_t oldsize,
64 u_char *new_buf,off_t newsize,off_t st,off_t en,off_t *pos)
65 {
66 off_t x,y;
67
68 if(en-st<2) {
69 x=matchlen(old+I[st],oldsize-I[st],new_buf,newsize);
70 y=matchlen(old+I[en],oldsize-I[en],new_buf,newsize);
71
72 if(x>y) {
73 *pos=I[st];
74 return x;
75 } else {
76 *pos=I[en];
77 return y;
78 }
79 };
80
81 x=st+(en-st)/2;
82 if(memcmp(old+I[x],new_buf,std::min(oldsize-I[x],newsize))<=0) {
83 return search(I,old,oldsize,new_buf,newsize,x,en,pos);
84 } else {
85 return search(I,old,oldsize,new_buf,newsize,st,x,pos);
86 };
87 }
88
offtout(off_t x,u_char * buf)89 static void offtout(off_t x,u_char *buf)
90 {
91 off_t y;
92
93 if(x<0) y=-x; else y=x;
94
95 buf[0]=y%256;y-=buf[0];
96 y=y/256;buf[1]=y%256;y-=buf[1];
97 y=y/256;buf[2]=y%256;y-=buf[2];
98 y=y/256;buf[3]=y%256;y-=buf[3];
99 y=y/256;buf[4]=y%256;y-=buf[4];
100 y=y/256;buf[5]=y%256;y-=buf[5];
101 y=y/256;buf[6]=y%256;y-=buf[6];
102 y=y/256;buf[7]=y%256;
103
104 if(x<0) buf[7]|=0x80;
105 }
106
bsdiff(const char * old_filename,const char * new_filename,const char * patch_filename)107 int bsdiff(const char* old_filename, const char* new_filename,
108 const char* patch_filename) {
109 int fd;
110 u_char *old_buf,*new_buf;
111 off_t oldsize,newsize;
112 saidx_t *I;
113 off_t scan,pos=0,len;
114 off_t lastscan,lastpos,lastoffset;
115 off_t oldscore,scsc;
116 off_t s,Sf,lenf,Sb,lenb;
117 off_t overlap,Ss,lens;
118 off_t i;
119 off_t dblen,eblen;
120 u_char *db,*eb;
121 u_char buf[8];
122 u_char header[32];
123 FILE * pf;
124 BZFILE * pfbz2;
125 int bz2err;
126
127 /* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
128 that we never try to malloc(0) and get a NULL pointer */
129 if(((fd=open(old_filename,O_RDONLY,0))<0) ||
130 ((oldsize=lseek(fd,0,SEEK_END))==-1) ||
131 ((old_buf=static_cast<u_char*>(malloc(oldsize+1)))==NULL) ||
132 (lseek(fd,0,SEEK_SET)!=0) ||
133 (read(fd,old_buf,oldsize)!=oldsize) ||
134 (close(fd)==-1)) err(1,"%s",old_filename);
135
136 if((I=static_cast<saidx_t*>(malloc((oldsize+1)*sizeof(saidx_t))))==NULL)
137 err(1,NULL);
138
139 if(divsufsort(old_buf, I, oldsize)) err(1, "divsufsort");
140
141 /* Allocate newsize+1 bytes instead of newsize bytes to ensure
142 that we never try to malloc(0) and get a NULL pointer */
143 if(((fd=open(new_filename,O_RDONLY,0))<0) ||
144 ((newsize=lseek(fd,0,SEEK_END))==-1) ||
145 ((new_buf = static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
146 (lseek(fd,0,SEEK_SET)!=0) ||
147 (read(fd,new_buf,newsize)!=newsize) ||
148 (close(fd)==-1)) err(1,"%s",new_filename);
149
150 if(((db=static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
151 ((eb=static_cast<u_char*>(malloc(newsize+1)))==NULL)) err(1,NULL);
152 dblen=0;
153 eblen=0;
154
155 /* Create the patch file */
156 if ((pf = fopen(patch_filename, "w")) == NULL)
157 err(1, "%s", patch_filename);
158
159 /* Header is
160 0 8 "BSDIFF40"
161 8 8 length of bzip2ed ctrl block
162 16 8 length of bzip2ed diff block
163 24 8 length of new file */
164 /* File is
165 0 32 Header
166 32 ?? Bzip2ed ctrl block
167 ?? ?? Bzip2ed diff block
168 ?? ?? Bzip2ed extra block */
169 memcpy(header,"BSDIFF40",8);
170 offtout(0, header + 8);
171 offtout(0, header + 16);
172 offtout(newsize, header + 24);
173 if (fwrite(header, 32, 1, pf) != 1)
174 err(1, "fwrite(%s)", patch_filename);
175
176 /* Compute the differences, writing ctrl as we go */
177 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
178 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
179 scan=0;len=0;
180 lastscan=0;lastpos=0;lastoffset=0;
181 while(scan<newsize) {
182 oldscore=0;
183
184 /* If we come across a large block of data that only differs
185 * by less than 8 bytes, this loop will take a long time to
186 * go past that block of data. We need to track the number of
187 * times we're stuck in the block and break out of it. */
188 int num_less_than_eight = 0;
189 off_t prev_len, prev_oldscore, prev_pos;
190 for(scsc=scan+=len;scan<newsize;scan++) {
191 prev_len=len;
192 prev_oldscore=oldscore;
193 prev_pos=pos;
194
195 len=search(I,old_buf,oldsize,new_buf+scan,newsize-scan,
196 0,oldsize,&pos);
197
198 for(;scsc<scan+len;scsc++)
199 if((scsc+lastoffset<oldsize) &&
200 (old_buf[scsc+lastoffset] == new_buf[scsc]))
201 oldscore++;
202
203 if(((len==oldscore) && (len!=0)) ||
204 (len>oldscore+8)) break;
205
206 if((scan+lastoffset<oldsize) &&
207 (old_buf[scan+lastoffset] == new_buf[scan]))
208 oldscore--;
209
210 const off_t fuzz = 8;
211 if (prev_len-fuzz<=len && len<=prev_len &&
212 prev_oldscore-fuzz<=oldscore &&
213 oldscore<=prev_oldscore &&
214 prev_pos<=pos && pos <=prev_pos+fuzz &&
215 oldscore<=len && len<=oldscore+fuzz)
216 ++num_less_than_eight;
217 else
218 num_less_than_eight=0;
219 if (num_less_than_eight > 100) break;
220 };
221
222 if((len!=oldscore) || (scan==newsize)) {
223 s=0;Sf=0;lenf=0;
224 for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
225 if(old_buf[lastpos+i]==new_buf[lastscan+i]) s++;
226 i++;
227 if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
228 };
229
230 lenb=0;
231 if(scan<newsize) {
232 s=0;Sb=0;
233 for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
234 if(old_buf[pos-i]==new_buf[scan-i]) s++;
235 if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
236 };
237 };
238
239 if(lastscan+lenf>scan-lenb) {
240 overlap=(lastscan+lenf)-(scan-lenb);
241 s=0;Ss=0;lens=0;
242 for(i=0;i<overlap;i++) {
243 if(new_buf[lastscan+lenf-overlap+i]==
244 old_buf[lastpos+lenf-overlap+i]) s++;
245 if(new_buf[scan-lenb+i]==
246 old_buf[pos-lenb+i]) s--;
247 if(s>Ss) { Ss=s; lens=i+1; };
248 };
249
250 lenf+=lens-overlap;
251 lenb-=lens;
252 };
253
254 for(i=0;i<lenf;i++)
255 db[dblen+i]=new_buf[lastscan+i]-old_buf[lastpos+i];
256 for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
257 eb[eblen+i]=new_buf[lastscan+lenf+i];
258
259 dblen+=lenf;
260 eblen+=(scan-lenb)-(lastscan+lenf);
261
262 offtout(lenf,buf);
263 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
264 if (bz2err != BZ_OK)
265 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
266
267 offtout((scan-lenb)-(lastscan+lenf),buf);
268 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
269 if (bz2err != BZ_OK)
270 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
271
272 offtout((pos-lenb)-(lastpos+lenf),buf);
273 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
274 if (bz2err != BZ_OK)
275 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
276
277 lastscan=scan-lenb;
278 lastpos=pos-lenb;
279 lastoffset=pos-scan;
280 };
281 };
282 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
283 if (bz2err != BZ_OK)
284 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
285
286 /* Compute size of compressed ctrl data */
287 if ((len = ftello(pf)) == -1)
288 err(1, "ftello");
289 offtout(len-32, header + 8);
290
291 /* Write compressed diff data */
292 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
293 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
294 BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
295 if (bz2err != BZ_OK)
296 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
297 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
298 if (bz2err != BZ_OK)
299 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
300
301 /* Compute size of compressed diff data */
302 if ((newsize = ftello(pf)) == -1)
303 err(1, "ftello");
304 offtout(newsize - len, header + 16);
305
306 /* Write compressed extra data */
307 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
308 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
309 BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
310 if (bz2err != BZ_OK)
311 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
312 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
313 if (bz2err != BZ_OK)
314 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
315
316 /* Seek to the beginning, write the header, and close the file */
317 if (fseeko(pf, 0, SEEK_SET))
318 err(1, "fseeko");
319 if (fwrite(header, 32, 1, pf) != 1)
320 err(1, "fwrite(%s)", patch_filename);
321 if (fclose(pf))
322 err(1, "fclose");
323
324 /* Free the memory we used */
325 free(db);
326 free(eb);
327 free(I);
328 free(old_buf);
329 free(new_buf);
330
331 return 0;
332 }
333
334 } // namespace bsdiff
335