bsdiff.c

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