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#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/types.h>
31
32#include <bzlib.h>
33#include <err.h>
34#include <fcntl.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38#include <unistd.h>
39
40#ifndef O_BINARY
41#define O_BINARY 0
42#endif
43
44#define MIN(x,y) (((x)<(y)) ? (x) : (y))
45
46static void split(off_t *I,off_t *V,off_t start,off_t len,off_t h)
47{
48	off_t i,j,k,x,tmp,jj,kk;
49
50	if(len<16) {
51		for(k=start;k<start+len;k+=j) {
52			j=1;x=V[I[k]+h];
53			for(i=1;k+i<start+len;i++) {
54				if(V[I[k+i]+h]<x) {
55					x=V[I[k+i]+h];
56					j=0;
57				};
58				if(V[I[k+i]+h]==x) {
59					tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
60					j++;
61				};
62			};
63			for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
64			if(j==1) I[k]=-1;
65		};
66		return;
67	};
68
69	x=V[I[start+len/2]+h];
70	jj=0;kk=0;
71	for(i=start;i<start+len;i++) {
72		if(V[I[i]+h]<x) jj++;
73		if(V[I[i]+h]==x) kk++;
74	};
75	jj+=start;kk+=jj;
76
77	i=start;j=0;k=0;
78	while(i<jj) {
79		if(V[I[i]+h]<x) {
80			i++;
81		} else if(V[I[i]+h]==x) {
82			tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
83			j++;
84		} else {
85			tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
86			k++;
87		};
88	};
89
90	while(jj+j<kk) {
91		if(V[I[jj+j]+h]==x) {
92			j++;
93		} else {
94			tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
95			k++;
96		};
97	};
98
99	if(jj>start) split(I,V,start,jj-start,h);
100
101	for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
102	if(jj==kk-1) I[jj]=-1;
103
104	if(start+len>kk) split(I,V,kk,start+len-kk,h);
105}
106
107static void qsufsort(off_t *I,off_t *V,u_char *old,off_t oldsize)
108{
109	off_t buckets[256];
110	off_t i,h,len;
111
112	for(i=0;i<256;i++) buckets[i]=0;
113	for(i=0;i<oldsize;i++) buckets[old[i]]++;
114	for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
115	for(i=255;i>0;i--) buckets[i]=buckets[i-1];
116	buckets[0]=0;
117
118	for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
119	I[0]=oldsize;
120	for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
121	V[oldsize]=0;
122	for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
123	I[0]=-1;
124
125	for(h=1;I[0]!=-(oldsize+1);h+=h) {
126		len=0;
127		for(i=0;i<oldsize+1;) {
128			if(I[i]<0) {
129				len-=I[i];
130				i-=I[i];
131			} else {
132				if(len) I[i-len]=-len;
133				len=V[I[i]]+1-i;
134				split(I,V,i,len,h);
135				i+=len;
136				len=0;
137			};
138		};
139		if(len) I[i-len]=-len;
140	};
141
142	for(i=0;i<oldsize+1;i++) I[V[i]]=i;
143}
144
145static off_t matchlen(u_char *old,off_t oldsize,u_char *new,off_t newsize)
146{
147	off_t i;
148
149	for(i=0;(i<oldsize)&&(i<newsize);i++)
150		if(old[i]!=new[i]) break;
151
152	return i;
153}
154
155static off_t search(off_t *I,u_char *old,off_t oldsize,
156		u_char *new,off_t newsize,off_t st,off_t en,off_t *pos)
157{
158	off_t x,y;
159
160	if(en-st<2) {
161		x=matchlen(old+I[st],oldsize-I[st],new,newsize);
162		y=matchlen(old+I[en],oldsize-I[en],new,newsize);
163
164		if(x>y) {
165			*pos=I[st];
166			return x;
167		} else {
168			*pos=I[en];
169			return y;
170		}
171	};
172
173	x=st+(en-st)/2;
174	if(memcmp(old+I[x],new,MIN(oldsize-I[x],newsize))<0) {
175		return search(I,old,oldsize,new,newsize,x,en,pos);
176	} else {
177		return search(I,old,oldsize,new,newsize,st,x,pos);
178	};
179}
180
181static void offtout(off_t x,u_char *buf)
182{
183	off_t y;
184
185	if(x<0) y=-x; else y=x;
186
187		buf[0]=y%256;y-=buf[0];
188	y=y/256;buf[1]=y%256;y-=buf[1];
189	y=y/256;buf[2]=y%256;y-=buf[2];
190	y=y/256;buf[3]=y%256;y-=buf[3];
191	y=y/256;buf[4]=y%256;y-=buf[4];
192	y=y/256;buf[5]=y%256;y-=buf[5];
193	y=y/256;buf[6]=y%256;y-=buf[6];
194	y=y/256;buf[7]=y%256;
195
196	if(x<0) buf[7]|=0x80;
197}
198
199int main(int argc,char *argv[])
200{
201	int fd;
202	u_char *old,*new;
203	off_t oldsize,newsize;
204	off_t *I,*V;
205	off_t scan,pos,len;
206	off_t lastscan,lastpos,lastoffset;
207	off_t oldscore,scsc;
208	off_t s,Sf,lenf,Sb,lenb;
209	off_t overlap,Ss,lens;
210	off_t i;
211	off_t dblen,eblen;
212	u_char *db,*eb;
213	u_char buf[8];
214	u_char header[32];
215	FILE * pf;
216	BZFILE * pfbz2;
217	int bz2err;
218
219	if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
220
221	/* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
222		that we never try to malloc(0) and get a NULL pointer */
223	if(((fd=open(argv[1],O_RDONLY|O_BINARY,0))<0) ||
224		((oldsize=lseek(fd,0,SEEK_END))==-1) ||
225		((old=malloc(oldsize+1))==NULL) ||
226		(lseek(fd,0,SEEK_SET)!=0) ||
227		(read(fd,old,oldsize)!=oldsize) ||
228		(close(fd)==-1)) err(1,"%s",argv[1]);
229
230	if(((I=malloc((oldsize+1)*sizeof(off_t)))==NULL) ||
231		((V=malloc((oldsize+1)*sizeof(off_t)))==NULL)) err(1,NULL);
232
233	qsufsort(I,V,old,oldsize);
234
235	free(V);
236
237	/* Allocate newsize+1 bytes instead of newsize bytes to ensure
238		that we never try to malloc(0) and get a NULL pointer */
239	if(((fd=open(argv[2],O_RDONLY|O_BINARY,0))<0) ||
240		((newsize=lseek(fd,0,SEEK_END))==-1) ||
241		((new=malloc(newsize+1))==NULL) ||
242		(lseek(fd,0,SEEK_SET)!=0) ||
243		(read(fd,new,newsize)!=newsize) ||
244		(close(fd)==-1)) err(1,"%s",argv[2]);
245
246	if(((db=malloc(newsize+1))==NULL) ||
247		((eb=malloc(newsize+1))==NULL)) err(1,NULL);
248	dblen=0;
249	eblen=0;
250
251	/* Create the patch file */
252	if ((pf = fopen(argv[3], "wb")) == NULL)
253		err(1, "%s", argv[3]);
254
255	/* Header is
256		0	8	 "BSDIFF40"
257		8	8	length of bzip2ed ctrl block
258		16	8	length of bzip2ed diff block
259		24	8	length of new file */
260	/* File is
261		0	32	Header
262		32	??	Bzip2ed ctrl block
263		??	??	Bzip2ed diff block
264		??	??	Bzip2ed extra block */
265	memcpy(header,"BSDIFF40",8);
266	offtout(0, header + 8);
267	offtout(0, header + 16);
268	offtout(newsize, header + 24);
269	if (fwrite(header, 32, 1, pf) != 1)
270		err(1, "fwrite(%s)", argv[3]);
271
272	/* Compute the differences, writing ctrl as we go */
273	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
274		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
275	scan=0;len=0;pos=0;
276	lastscan=0;lastpos=0;lastoffset=0;
277	while(scan<newsize) {
278		oldscore=0;
279
280		for(scsc=scan+=len;scan<newsize;scan++) {
281			len=search(I,old,oldsize,new+scan,newsize-scan,
282					0,oldsize,&pos);
283
284			for(;scsc<scan+len;scsc++)
285			if((scsc+lastoffset<oldsize) &&
286				(old[scsc+lastoffset] == new[scsc]))
287				oldscore++;
288
289			if(((len==oldscore) && (len!=0)) ||
290				(len>oldscore+8)) break;
291
292			if((scan+lastoffset<oldsize) &&
293				(old[scan+lastoffset] == new[scan]))
294				oldscore--;
295		};
296
297		if((len!=oldscore) || (scan==newsize)) {
298			s=0;Sf=0;lenf=0;
299			for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
300				if(old[lastpos+i]==new[lastscan+i]) s++;
301				i++;
302				if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
303			};
304
305			lenb=0;
306			if(scan<newsize) {
307				s=0;Sb=0;
308				for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
309					if(old[pos-i]==new[scan-i]) s++;
310					if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
311				};
312			};
313
314			if(lastscan+lenf>scan-lenb) {
315				overlap=(lastscan+lenf)-(scan-lenb);
316				s=0;Ss=0;lens=0;
317				for(i=0;i<overlap;i++) {
318					if(new[lastscan+lenf-overlap+i]==
319					   old[lastpos+lenf-overlap+i]) s++;
320					if(new[scan-lenb+i]==
321					   old[pos-lenb+i]) s--;
322					if(s>Ss) { Ss=s; lens=i+1; };
323				};
324
325				lenf+=lens-overlap;
326				lenb-=lens;
327			};
328
329			for(i=0;i<lenf;i++)
330				db[dblen+i]=new[lastscan+i]-old[lastpos+i];
331			for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
332				eb[eblen+i]=new[lastscan+lenf+i];
333
334			dblen+=lenf;
335			eblen+=(scan-lenb)-(lastscan+lenf);
336
337			offtout(lenf,buf);
338			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
339			if (bz2err != BZ_OK)
340				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
341
342			offtout((scan-lenb)-(lastscan+lenf),buf);
343			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
344			if (bz2err != BZ_OK)
345				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
346
347			offtout((pos-lenb)-(lastpos+lenf),buf);
348			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
349			if (bz2err != BZ_OK)
350				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
351
352			lastscan=scan-lenb;
353			lastpos=pos-lenb;
354			lastoffset=pos-scan;
355		};
356	};
357	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
358	if (bz2err != BZ_OK)
359		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
360
361	/* Compute size of compressed ctrl data */
362	if ((len = ftello(pf)) == -1)
363		err(1, "ftello");
364	offtout(len-32, header + 8);
365
366	/* Write compressed diff data */
367	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
368		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
369	BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
370	if (bz2err != BZ_OK)
371		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
372	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
373	if (bz2err != BZ_OK)
374		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
375
376	/* Compute size of compressed diff data */
377	if ((newsize = ftello(pf)) == -1)
378		err(1, "ftello");
379	offtout(newsize - len, header + 16);
380
381	/* Write compressed extra data */
382	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
383		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
384	BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
385	if (bz2err != BZ_OK)
386		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
387	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
388	if (bz2err != BZ_OK)
389		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
390
391	/* Seek to the beginning, write the header, and close the file */
392	if (fseeko(pf, 0, SEEK_SET))
393		err(1, "fseeko");
394	if (fwrite(header, 32, 1, pf) != 1)
395		err(1, "fwrite(%s)", argv[3]);
396	if (fclose(pf))
397		err(1, "fclose");
398
399	/* Free the memory we used */
400	free(db);
401	free(eb);
402	free(I);
403	free(old);
404	free(new);
405
406	return 0;
407}
408