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 "bsdiff.h"
32
33 #include <sys/types.h>
34
35 #include <bzlib.h>
36 #include <err.h>
37 #include <fcntl.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42
43 #include <algorithm>
44
45 namespace bsdiff {
46
matchlen(const u_char * old,off_t oldsize,const u_char * new_buf,off_t newsize)47 static off_t matchlen(const u_char* old, off_t oldsize, const u_char* new_buf,
48 off_t newsize) {
49 off_t i;
50
51 for(i=0;(i<oldsize)&&(i<newsize);i++)
52 if(old[i]!=new_buf[i]) break;
53
54 return i;
55 }
56
57 // This is a binary search of the string |new_buf| of size |newsize| (or a
58 // prefix of it) in the |old| string with size |oldsize| using the suffix array
59 // |I|. |st| and |en| is the start and end of the search range (inclusive).
60 // Returns the length of the longest prefix found and stores the position of the
61 // string found in |*pos|.
search(saidx_t * I,const u_char * old,off_t oldsize,const u_char * new_buf,off_t newsize,off_t st,off_t en,off_t * pos)62 static off_t search(saidx_t* I, const u_char* old, off_t oldsize,
63 const u_char* new_buf, off_t newsize, off_t st, off_t en,
64 off_t* pos) {
65 off_t x,y;
66
67 if(en-st<2) {
68 x=matchlen(old+I[st],oldsize-I[st],new_buf,newsize);
69 y=matchlen(old+I[en],oldsize-I[en],new_buf,newsize);
70
71 if(x>y) {
72 *pos=I[st];
73 return x;
74 } else {
75 *pos=I[en];
76 return y;
77 }
78 };
79
80 x=st+(en-st)/2;
81 if(memcmp(old+I[x],new_buf,std::min(oldsize-I[x],newsize))<=0) {
82 return search(I,old,oldsize,new_buf,newsize,x,en,pos);
83 } else {
84 return search(I,old,oldsize,new_buf,newsize,st,x,pos);
85 };
86 }
87
offtout(off_t x,u_char * buf)88 static void offtout(off_t x,u_char *buf)
89 {
90 off_t y;
91
92 if(x<0) y=-x; else y=x;
93
94 buf[0]=y%256;y-=buf[0];
95 y=y/256;buf[1]=y%256;y-=buf[1];
96 y=y/256;buf[2]=y%256;y-=buf[2];
97 y=y/256;buf[3]=y%256;y-=buf[3];
98 y=y/256;buf[4]=y%256;y-=buf[4];
99 y=y/256;buf[5]=y%256;y-=buf[5];
100 y=y/256;buf[6]=y%256;y-=buf[6];
101 y=y/256;buf[7]=y%256;
102
103 if(x<0) buf[7]|=0x80;
104 }
105
bsdiff(const char * old_filename,const char * new_filename,const char * patch_filename)106 int bsdiff(const char* old_filename, const char* new_filename,
107 const char* patch_filename) {
108 int fd;
109 u_char *old_buf,*new_buf;
110 off_t oldsize,newsize;
111
112 /* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
113 that we never try to malloc(0) and get a NULL pointer */
114 if(((fd=open(old_filename,O_RDONLY,0))<0) ||
115 ((oldsize=lseek(fd,0,SEEK_END))==-1) ||
116 ((old_buf=static_cast<u_char*>(malloc(oldsize+1)))==NULL) ||
117 (lseek(fd,0,SEEK_SET)!=0) ||
118 (read(fd,old_buf,oldsize)!=oldsize) ||
119 (close(fd)==-1)) err(1,"%s",old_filename);
120
121 /* Allocate newsize+1 bytes instead of newsize bytes to ensure
122 that we never try to malloc(0) and get a NULL pointer */
123 if(((fd=open(new_filename,O_RDONLY,0))<0) ||
124 ((newsize=lseek(fd,0,SEEK_END))==-1) ||
125 ((new_buf = static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
126 (lseek(fd,0,SEEK_SET)!=0) ||
127 (read(fd,new_buf,newsize)!=newsize) ||
128 (close(fd)==-1)) err(1,"%s",new_filename);
129
130 int ret = bsdiff(old_buf, oldsize, new_buf, newsize, patch_filename, nullptr);
131
132 free(old_buf);
133 free(new_buf);
134
135 return ret;
136 }
137
138 // Generate bsdiff patch from |old_buf| to |new_buf|, save the patch file to
139 // |patch_filename|. Returns 0 on success.
140 // |I_cache| can be used to cache the suffix array if the same |old_buf| is used
141 // repeatedly, pass nullptr if not needed.
bsdiff(const u_char * old_buf,off_t oldsize,const u_char * new_buf,off_t newsize,const char * patch_filename,saidx_t ** I_cache)142 int bsdiff(const u_char* old_buf, off_t oldsize, const u_char* new_buf,
143 off_t newsize, const char* patch_filename, saidx_t** I_cache) {
144 saidx_t *I;
145 off_t scan,pos=0,len;
146 off_t lastscan,lastpos,lastoffset;
147 off_t oldscore,scsc;
148 off_t s,Sf,lenf,Sb,lenb;
149 off_t overlap,Ss,lens;
150 off_t i;
151 off_t dblen,eblen;
152 u_char *db,*eb;
153 u_char buf[8];
154 u_char header[32];
155 FILE * pf;
156 BZFILE * pfbz2;
157 int bz2err;
158
159 if (I_cache && *I_cache) {
160 I = *I_cache;
161 } else {
162 if ((I=static_cast<saidx_t*>(malloc((oldsize+1)*sizeof(saidx_t))))==NULL)
163 err(1,NULL);
164
165 if (divsufsort(old_buf, I, oldsize)) err(1, "divsufsort");
166 if (I_cache)
167 *I_cache = I;
168 }
169
170 if(((db=static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
171 ((eb=static_cast<u_char*>(malloc(newsize+1)))==NULL)) err(1,NULL);
172 dblen=0;
173 eblen=0;
174
175 /* Create the patch file */
176 if ((pf = fopen(patch_filename, "w")) == NULL)
177 err(1, "%s", patch_filename);
178
179 /* Header is
180 0 8 "BSDIFF40"
181 8 8 length of bzip2ed ctrl block
182 16 8 length of bzip2ed diff block
183 24 8 length of new file */
184 /* File is
185 0 32 Header
186 32 ?? Bzip2ed ctrl block
187 ?? ?? Bzip2ed diff block
188 ?? ?? Bzip2ed extra block */
189 memcpy(header,"BSDIFF40",8);
190 offtout(0, header + 8);
191 offtout(0, header + 16);
192 offtout(newsize, header + 24);
193 if (fwrite(header, 32, 1, pf) != 1)
194 err(1, "fwrite(%s)", patch_filename);
195
196 /* Compute the differences, writing ctrl as we go */
197 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
198 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
199 scan=0;len=0;
200 lastscan=0;lastpos=0;lastoffset=0;
201 while(scan<newsize) {
202 oldscore=0;
203
204 /* If we come across a large block of data that only differs
205 * by less than 8 bytes, this loop will take a long time to
206 * go past that block of data. We need to track the number of
207 * times we're stuck in the block and break out of it. */
208 int num_less_than_eight = 0;
209 off_t prev_len, prev_oldscore, prev_pos;
210 for(scsc=scan+=len;scan<newsize;scan++) {
211 prev_len=len;
212 prev_oldscore=oldscore;
213 prev_pos=pos;
214
215 len=search(I,old_buf,oldsize,new_buf+scan,newsize-scan,
216 0,oldsize-1,&pos);
217
218 for(;scsc<scan+len;scsc++)
219 if((scsc+lastoffset<oldsize) &&
220 (old_buf[scsc+lastoffset] == new_buf[scsc]))
221 oldscore++;
222
223 if(((len==oldscore) && (len!=0)) ||
224 (len>oldscore+8)) break;
225
226 if((scan+lastoffset<oldsize) &&
227 (old_buf[scan+lastoffset] == new_buf[scan]))
228 oldscore--;
229
230 const off_t fuzz = 8;
231 if (prev_len-fuzz<=len && len<=prev_len &&
232 prev_oldscore-fuzz<=oldscore &&
233 oldscore<=prev_oldscore &&
234 prev_pos<=pos && pos <=prev_pos+fuzz &&
235 oldscore<=len && len<=oldscore+fuzz)
236 ++num_less_than_eight;
237 else
238 num_less_than_eight=0;
239 if (num_less_than_eight > 100) break;
240 };
241
242 if((len!=oldscore) || (scan==newsize)) {
243 s=0;Sf=0;lenf=0;
244 for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
245 if(old_buf[lastpos+i]==new_buf[lastscan+i]) s++;
246 i++;
247 if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
248 };
249
250 lenb=0;
251 if(scan<newsize) {
252 s=0;Sb=0;
253 for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
254 if(old_buf[pos-i]==new_buf[scan-i]) s++;
255 if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
256 };
257 };
258
259 if(lastscan+lenf>scan-lenb) {
260 overlap=(lastscan+lenf)-(scan-lenb);
261 s=0;Ss=0;lens=0;
262 for(i=0;i<overlap;i++) {
263 if(new_buf[lastscan+lenf-overlap+i]==
264 old_buf[lastpos+lenf-overlap+i]) s++;
265 if(new_buf[scan-lenb+i]==
266 old_buf[pos-lenb+i]) s--;
267 if(s>Ss) { Ss=s; lens=i+1; };
268 };
269
270 lenf+=lens-overlap;
271 lenb-=lens;
272 };
273
274 for(i=0;i<lenf;i++)
275 db[dblen+i]=new_buf[lastscan+i]-old_buf[lastpos+i];
276 for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
277 eb[eblen+i]=new_buf[lastscan+lenf+i];
278
279 dblen+=lenf;
280 eblen+=(scan-lenb)-(lastscan+lenf);
281
282 offtout(lenf,buf);
283 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
284 if (bz2err != BZ_OK)
285 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
286
287 offtout((scan-lenb)-(lastscan+lenf),buf);
288 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
289 if (bz2err != BZ_OK)
290 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
291
292 offtout((pos-lenb)-(lastpos+lenf),buf);
293 BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
294 if (bz2err != BZ_OK)
295 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
296
297 lastscan=scan-lenb;
298 lastpos=pos-lenb;
299 lastoffset=pos-scan;
300 };
301 };
302 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
303 if (bz2err != BZ_OK)
304 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
305
306 /* Compute size of compressed ctrl data */
307 if ((len = ftello(pf)) == -1)
308 err(1, "ftello");
309 offtout(len-32, header + 8);
310
311 /* Write compressed diff data */
312 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
313 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
314 BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
315 if (bz2err != BZ_OK)
316 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
317 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
318 if (bz2err != BZ_OK)
319 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
320
321 /* Compute size of compressed diff data */
322 if ((newsize = ftello(pf)) == -1)
323 err(1, "ftello");
324 offtout(newsize - len, header + 16);
325
326 /* Write compressed extra data */
327 if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
328 errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
329 BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
330 if (bz2err != BZ_OK)
331 errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
332 BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
333 if (bz2err != BZ_OK)
334 errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
335
336 /* Seek to the beginning, write the header, and close the file */
337 if (fseeko(pf, 0, SEEK_SET))
338 err(1, "fseeko");
339 if (fwrite(header, 32, 1, pf) != 1)
340 err(1, "fwrite(%s)", patch_filename);
341 if (fclose(pf))
342 err(1, "fclose");
343
344 /* Free the memory we used */
345 free(db);
346 free(eb);
347 if (I_cache == nullptr)
348 free(I);
349
350 return 0;
351 }
352
353 } // namespace bsdiff
354