1 static char sccsid[] = "@(#)diffreg.c 4.1 10/09/80"; 2 3 #include "diff.h" 4 /* 5 * diff - compare two files. 6 */ 7 8 /* 9 * Uses an algorithm due to Harold Stone, which finds 10 * a pair of longest identical subsequences in the two 11 * files. 12 * 13 * The major goal is to generate the match vector J. 14 * J[i] is the index of the line in file1 corresponding 15 * to line i file0. J[i] = 0 if there is no 16 * such line in file1. 17 * 18 * Lines are hashed so as to work in core. All potential 19 * matches are located by sorting the lines of each file 20 * on the hash (called ``value''). In particular, this 21 * collects the equivalence classes in file1 together. 22 * Subroutine equiv replaces the value of each line in 23 * file0 by the index of the first element of its 24 * matching equivalence in (the reordered) file1. 25 * To save space equiv squeezes file1 into a single 26 * array member in which the equivalence classes 27 * are simply concatenated, except that their first 28 * members are flagged by changing sign. 29 * 30 * Next the indices that point into member are unsorted into 31 * array class according to the original order of file0. 32 * 33 * The cleverness lies in routine stone. This marches 34 * through the lines of file0, developing a vector klist 35 * of "k-candidates". At step i a k-candidate is a matched 36 * pair of lines x,y (x in file0 y in file1) such that 37 * there is a common subsequence of length k 38 * between the first i lines of file0 and the first y 39 * lines of file1, but there is no such subsequence for 40 * any smaller y. x is the earliest possible mate to y 41 * that occurs in such a subsequence. 42 * 43 * Whenever any of the members of the equivalence class of 44 * lines in file1 matable to a line in file0 has serial number 45 * less than the y of some k-candidate, that k-candidate 46 * with the smallest such y is replaced. The new 47 * k-candidate is chained (via pred) to the current 48 * k-1 candidate so that the actual subsequence can 49 * be recovered. When a member has serial number greater 50 * that the y of all k-candidates, the klist is extended. 51 * At the end, the longest subsequence is pulled out 52 * and placed in the array J by unravel 53 * 54 * With J in hand, the matches there recorded are 55 * check'ed against reality to assure that no spurious 56 * matches have crept in due to hashing. If they have, 57 * they are broken, and "jackpot" is recorded--a harmless 58 * matter except that a true match for a spuriously 59 * mated line may now be unnecessarily reported as a change. 60 * 61 * Much of the complexity of the program comes simply 62 * from trying to minimize core utilization and 63 * maximize the range of doable problems by dynamically 64 * allocating what is needed and reusing what is not. 65 * The core requirements for problems larger than somewhat 66 * are (in words) 2*length(file0) + length(file1) + 67 * 3*(number of k-candidates installed), typically about 68 * 6n words for files of length n. 69 */ 70 71 #define prints(s) fputs(s,stdout) 72 73 FILE *input[2]; 74 FILE *fopen(); 75 76 struct cand { 77 int x; 78 int y; 79 int pred; 80 } cand; 81 struct line { 82 int serial; 83 int value; 84 } *file[2], line; 85 int len[2]; 86 struct line *sfile[2]; /* shortened by pruning common prefix and suffix */ 87 int slen[2]; 88 int pref, suff; /* length of prefix and suffix */ 89 int *class; /* will be overlaid on file[0] */ 90 int *member; /* will be overlaid on file[1] */ 91 int *klist; /* will be overlaid on file[0] after class */ 92 struct cand *clist; /* merely a free storage pot for candidates */ 93 int clen = 0; 94 int *J; /* will be overlaid on class */ 95 long *ixold; /* will be overlaid on klist */ 96 long *ixnew; /* will be overlaid on file[1] */ 97 98 diffreg() 99 { 100 register int k; 101 102 if (hflag) { 103 diffargv[0] = "diffh"; 104 execv(diffh, diffargv); 105 fprintf(stderr, "diff: "); 106 perror(diffh); 107 done(); 108 } 109 dummy = malloc(1); 110 if ((stb1.st_mode & S_IFMT) == S_IFDIR) 111 file1 = splice(file1, file2); 112 else if ((stb2.st_mode & S_IFMT) == S_IFDIR) 113 file2 = splice(file2, file1); 114 else if (!strcmp(file1, "-")) { 115 if (!strcmp(file2, "-")) { 116 fprintf(stderr, "diff: can't specify - -\n"); 117 done(); 118 } 119 file1 = copytemp(); 120 } else if (!strcmp(file2, "-")) 121 file2 = copytemp(); 122 prepare(0, file1); 123 prepare(1, file2); 124 prune(); 125 sort(sfile[0],slen[0]); 126 sort(sfile[1],slen[1]); 127 128 member = (int *)file[1]; 129 equiv(sfile[0], slen[0], sfile[1], slen[1], member); 130 member = (int *)ralloc((char *)member,(slen[1]+2)*sizeof(int)); 131 132 class = (int *)file[0]; 133 unsort(sfile[0], slen[0], class); 134 class = (int *)ralloc((char *)class,(slen[0]+2)*sizeof(int)); 135 136 klist = (int *)talloc((slen[0]+2)*sizeof(int)); 137 clist = (struct cand *)talloc(sizeof(cand)); 138 k = stone(class, slen[0], member, klist); 139 free((char *)member); 140 free((char *)class); 141 142 J = (int *)talloc((len[0]+2)*sizeof(int)); 143 unravel(klist[k]); 144 free((char *)clist); 145 free((char *)klist); 146 147 ixold = (long *)talloc((len[0]+2)*sizeof(long)); 148 ixnew = (long *)talloc((len[1]+2)*sizeof(long)); 149 check(); 150 output(); 151 status = anychange; 152 if (opt == D_CONTEXT && anychange == 0) 153 printf("No differences encountered\n"); 154 done(); 155 } 156 157 char * 158 copytemp() 159 { 160 char buf[BUFSIZ]; 161 register int i, f; 162 163 signal(SIGHUP,done); 164 signal(SIGINT,done); 165 signal(SIGPIPE,done); 166 signal(SIGTERM,done); 167 tempfile = mktemp("/tmp/dXXXXX"); 168 f = creat(tempfile,0600); 169 if (f < 0) { 170 fprintf("diff: "); 171 perror(tempfile); 172 done(); 173 } 174 while ((i = read(0,buf,BUFSIZ)) > 0) 175 if (write(f,buf,i) != i) { 176 fprintf(stderr, "diff: "); 177 perror(tempfile); 178 done(); 179 } 180 close(f); 181 return (tempfile); 182 } 183 184 char * 185 splice(dir, file) 186 char *dir, *file; 187 { 188 char *tail; 189 char buf[BUFSIZ]; 190 191 if (!strcmp(file, "-")) { 192 fprintf(stderr, "diff: can't specify - with other arg directory\n"); 193 done(); 194 } 195 tail = rindex(file, '/'); 196 if (tail == 0) 197 tail = file; 198 else 199 tail++; 200 sprintf(buf, "%s/%s", dir, tail); 201 return (savestr(buf)); 202 } 203 204 prepare(i, arg) 205 char *arg; 206 { 207 register struct line *p; 208 register j,h; 209 if((input[i] = fopen(arg,"r")) == NULL){ 210 fprintf(stderr, "diff: "); 211 perror(arg); 212 done(); 213 } 214 p = (struct line *)talloc(3*sizeof(line)); 215 for(j=0; h=readhash(input[i]);) { 216 p = (struct line *)ralloc((char *)p,(++j+3)*sizeof(line)); 217 p[j].value = h; 218 } 219 len[i] = j; 220 file[i] = p; 221 fclose(input[i]); 222 } 223 224 prune() 225 { 226 register i,j; 227 for(pref=0;pref<len[0]&&pref<len[1]&& 228 file[0][pref+1].value==file[1][pref+1].value; 229 pref++ ) ; 230 for(suff=0;suff<len[0]-pref&&suff<len[1]-pref&& 231 file[0][len[0]-suff].value==file[1][len[1]-suff].value; 232 suff++) ; 233 for(j=0;j<2;j++) { 234 sfile[j] = file[j]+pref; 235 slen[j] = len[j]-pref-suff; 236 for(i=0;i<=slen[j];i++) 237 sfile[j][i].serial = i; 238 } 239 } 240 241 equiv(a,n,b,m,c) 242 struct line *a, *b; 243 int *c; 244 { 245 register int i, j; 246 i = j = 1; 247 while(i<=n && j<=m) { 248 if(a[i].value <b[j].value) 249 a[i++].value = 0; 250 else if(a[i].value == b[j].value) 251 a[i++].value = j; 252 else 253 j++; 254 } 255 while(i <= n) 256 a[i++].value = 0; 257 b[m+1].value = 0; 258 j = 0; 259 while(++j <= m) { 260 c[j] = -b[j].serial; 261 while(b[j+1].value == b[j].value) { 262 j++; 263 c[j] = b[j].serial; 264 } 265 } 266 c[j] = -1; 267 } 268 269 stone(a,n,b,c) 270 int *a; 271 int *b; 272 int *c; 273 { 274 register int i, k,y; 275 int j, l; 276 int oldc, tc; 277 int oldl; 278 k = 0; 279 c[0] = newcand(0,0,0); 280 for(i=1; i<=n; i++) { 281 j = a[i]; 282 if(j==0) 283 continue; 284 y = -b[j]; 285 oldl = 0; 286 oldc = c[0]; 287 do { 288 if(y <= clist[oldc].y) 289 continue; 290 l = search(c, k, y); 291 if(l!=oldl+1) 292 oldc = c[l-1]; 293 if(l<=k) { 294 if(clist[c[l]].y <= y) 295 continue; 296 tc = c[l]; 297 c[l] = newcand(i,y,oldc); 298 oldc = tc; 299 oldl = l; 300 } else { 301 c[l] = newcand(i,y,oldc); 302 k++; 303 break; 304 } 305 } while((y=b[++j]) > 0); 306 } 307 return(k); 308 } 309 310 newcand(x,y,pred) 311 { 312 register struct cand *q; 313 clist = (struct cand *)ralloc((char *)clist,++clen*sizeof(cand)); 314 q = clist + clen -1; 315 q->x = x; 316 q->y = y; 317 q->pred = pred; 318 return(clen-1); 319 } 320 321 search(c, k, y) 322 int *c; 323 { 324 register int i, j, l; 325 int t; 326 if(clist[c[k]].y<y) /*quick look for typical case*/ 327 return(k+1); 328 i = 0; 329 j = k+1; 330 while((l=(i+j)/2) > i) { 331 t = clist[c[l]].y; 332 if(t > y) 333 j = l; 334 else if(t < y) 335 i = l; 336 else 337 return(l); 338 } 339 return(l+1); 340 } 341 342 unravel(p) 343 { 344 register int i; 345 register struct cand *q; 346 for(i=0; i<=len[0]; i++) 347 J[i] = i<=pref ? i: 348 i>len[0]-suff ? i+len[1]-len[0]: 349 0; 350 for(q=clist+p;q->y!=0;q=clist+q->pred) 351 J[q->x+pref] = q->y+pref; 352 } 353 354 /* check does double duty: 355 1. ferret out any fortuitous correspondences due 356 to confounding by hashing (which result in "jackpot") 357 2. collect random access indexes to the two files */ 358 359 check() 360 { 361 register int i, j; 362 int jackpot; 363 long ctold, ctnew; 364 char c,d; 365 input[0] = fopen(file1,"r"); 366 input[1] = fopen(file2,"r"); 367 j = 1; 368 ixold[0] = ixnew[0] = 0; 369 jackpot = 0; 370 ctold = ctnew = 0; 371 for(i=1;i<=len[0];i++) { 372 if(J[i]==0) { 373 ixold[i] = ctold += skipline(0); 374 continue; 375 } 376 while(j<J[i]) { 377 ixnew[j] = ctnew += skipline(1); 378 j++; 379 } 380 for(;;) { 381 c = getc(input[0]); 382 d = getc(input[1]); 383 ctold++; 384 ctnew++; 385 if(bflag && isspace(c) && isspace(d)) { 386 do { 387 if(c=='\n') break; 388 ctold++; 389 } while(isspace(c=getc(input[0]))); 390 do { 391 if(d=='\n') break; 392 ctnew++; 393 } while(isspace(d=getc(input[1]))); 394 } 395 if(c!=d) { 396 jackpot++; 397 J[i] = 0; 398 if(c!='\n') 399 ctold += skipline(0); 400 if(d!='\n') 401 ctnew += skipline(1); 402 break; 403 } 404 if(c=='\n') 405 break; 406 } 407 ixold[i] = ctold; 408 ixnew[j] = ctnew; 409 j++; 410 } 411 for(;j<=len[1];j++) { 412 ixnew[j] = ctnew += skipline(1); 413 } 414 fclose(input[0]); 415 fclose(input[1]); 416 /* 417 if(jackpot) 418 fprintf(stderr, "jackpot\n"); 419 */ 420 } 421 422 sort(a,n) /*shellsort CACM #201*/ 423 struct line *a; 424 { 425 struct line w; 426 register int j,m; 427 struct line *ai; 428 register struct line *aim; 429 int k; 430 for(j=1;j<=n;j*= 2) 431 m = 2*j - 1; 432 for(m/=2;m!=0;m/=2) { 433 k = n-m; 434 for(j=1;j<=k;j++) { 435 for(ai = &a[j]; ai > a; ai -= m) { 436 aim = &ai[m]; 437 if(aim < ai) 438 break; /*wraparound*/ 439 if(aim->value > ai[0].value || 440 aim->value == ai[0].value && 441 aim->serial > ai[0].serial) 442 break; 443 w.value = ai[0].value; 444 ai[0].value = aim->value; 445 aim->value = w.value; 446 w.serial = ai[0].serial; 447 ai[0].serial = aim->serial; 448 aim->serial = w.serial; 449 } 450 } 451 } 452 } 453 454 unsort(f, l, b) 455 struct line *f; 456 int *b; 457 { 458 register int *a; 459 register int i; 460 a = (int *)talloc((l+1)*sizeof(int)); 461 for(i=1;i<=l;i++) 462 a[f[i].serial] = f[i].value; 463 for(i=1;i<=l;i++) 464 b[i] = a[i]; 465 free((char *)a); 466 } 467 468 skipline(f) 469 { 470 register i; 471 for(i=1;getc(input[f])!='\n';i++) ; 472 return(i); 473 } 474 475 output() 476 { 477 int m; 478 register int i0, i1, j1; 479 int j0; 480 input[0] = fopen(file1,"r"); 481 input[1] = fopen(file2,"r"); 482 m = len[0]; 483 J[0] = 0; 484 J[m+1] = len[1]+1; 485 if(opt!=D_EDIT) for(i0=1;i0<=m;i0=i1+1) { 486 while(i0<=m&&J[i0]==J[i0-1]+1) i0++; 487 j0 = J[i0-1]+1; 488 i1 = i0-1; 489 while(i1<m&&J[i1+1]==0) i1++; 490 j1 = J[i1+1]-1; 491 J[i1] = j1; 492 change(i0,i1,j0,j1); 493 } else for(i0=m;i0>=1;i0=i1-1) { 494 while(i0>=1&&J[i0]==J[i0+1]-1&&J[i0]!=0) i0--; 495 j0 = J[i0+1]-1; 496 i1 = i0+1; 497 while(i1>1&&J[i1-1]==0) i1--; 498 j1 = J[i1-1]+1; 499 J[i1] = j1; 500 change(i1,i0,j1,j0); 501 } 502 if(m==0) 503 change(1,0,1,len[1]); 504 if (opt==D_IFDEF) { 505 for (;;) { 506 #define c i0 507 c = getc(input[0]); 508 if (c < 0) 509 return; 510 putchar(c); 511 } 512 #undef c 513 } 514 } 515 516 /* indicate that there is a difference between lines a and b of the from file 517 to get to lines c to d of the to file. 518 If a is greater then b then there are no lines in the from file involved 519 and this means that there were lines appended (beginning at b). 520 If c is greater than d then there are lines missing from the to file. 521 */ 522 change(a,b,c,d) 523 { 524 char ch; 525 int lowa,upb,lowc,upd; 526 struct stat stbuf; 527 528 if (opt != D_IFDEF && a>b && c>d) 529 return; 530 if (anychange == 0) { 531 anychange = 1; 532 if(opt == D_CONTEXT) { 533 printf("*** %s ", file1); 534 stat(file1, &stbuf); 535 printf("%s--- %s ", 536 ctime(&stbuf.st_mtime), file2); 537 stat(file2, &stbuf); 538 printf("%s", ctime(&stbuf.st_mtime)); 539 } 540 } 541 if (a <= b && c <= d) 542 ch = 'c'; 543 else 544 ch = (a <= b) ? 'd' : 'a'; 545 if(opt == D_CONTEXT) { 546 lowa = max(1, a-context); 547 upb = min(len[0], b+context); 548 lowc = max(1, c-context); 549 upd = min(len[1], d+context); 550 551 /* print out from file */ 552 printf("***************\n*** "); 553 range(lowa,upb,","); 554 printf("\n"); 555 if (ch == 'a') 556 fetch(ixold,lowa,upb,input[0]," "); 557 else { 558 fetch(ixold,lowa,a-1,input[0]," "); 559 fetch(ixold,a,b,input[0],ch == 'c' ? "! " : "- "); 560 fetch(ixold,b+1,upb,input[0]," "); 561 } 562 putchar('\n'); 563 printf("--- "); 564 range(lowc,upd,","); 565 printf(" -----\n"); 566 if (ch == 'd') 567 fetch(ixnew,lowc,upd,input[1]," "); 568 else { 569 fetch(ixnew,lowc,c-1,input[1]," "); 570 fetch(ixnew,c,d,input[1],ch == 'c' ? "! " : "+ "); 571 fetch(ixnew,d+1,upd,input[1]," "); 572 } 573 return; 574 } 575 switch (opt) { 576 577 case D_NORMAL: 578 case D_EDIT: 579 range(a,b,","); 580 putchar(a>b?'a':c>d?'d':'c'); 581 if(opt==D_NORMAL) 582 range(c,d,","); 583 putchar('\n'); 584 break; 585 case D_REVERSE: 586 putchar(a>b?'a':c>d?'d':'c'); 587 range(a,b," "); 588 putchar('\n'); 589 break; 590 } 591 if(opt == D_NORMAL || opt == D_IFDEF) { 592 fetch(ixold,a,b,input[0],"< ", 1); 593 if(a<=b&&c<=d && opt == D_NORMAL) 594 prints("---\n"); 595 } 596 fetch(ixnew,c,d,input[1],opt==D_NORMAL?"> ":"", 0); 597 if ((opt ==D_EDIT || opt == D_REVERSE) && c<=d) 598 prints(".\n"); 599 if (inifdef) { 600 fprintf(stdout, "#endif %s\n", endifname); 601 inifdef = 0; 602 } 603 } 604 605 range(a,b,separator) 606 char *separator; 607 { 608 printf("%d", a>b?b:a); 609 if(a<b) { 610 printf("%s%d", separator, b); 611 } 612 } 613 614 fetch(f,a,b,lb,s,oldfile) 615 long *f; 616 FILE *lb; 617 char *s; 618 { 619 register int i, j; 620 register int nc; 621 int oneflag = (*ifdef1!='\0') != (*ifdef2!='\0'); 622 623 /* 624 * When doing #ifdef's, copy down to current line 625 * if this is the first file, so that stuff makes it to output. 626 */ 627 if (opt == D_IFDEF && oldfile){ 628 long curpos = ftell(lb); 629 /* print through if append (a>b), else to (nb: 0 vs 1 orig) */ 630 nc = f[a>b? b : a-1 ] - curpos; 631 for (i = 0; i < nc; i++) 632 putchar(getc(lb)); 633 } 634 if (a > b) 635 return; 636 if (opt == D_IFDEF) { 637 if (inifdef) 638 fprintf(stdout, "#else %s%s\n", oneflag && oldfile==1 ? "!" : "", ifdef2); 639 else { 640 if (oneflag) { 641 /* There was only one ifdef given */ 642 endifname = ifdef2; 643 if (oldfile) 644 fprintf(stdout, "#ifndef %s\n", endifname); 645 else 646 fprintf(stdout, "#ifdef %s\n", endifname); 647 } 648 else { 649 endifname = oldfile ? ifdef1 : ifdef2; 650 fprintf(stdout, "#ifdef %s\n", endifname); 651 } 652 } 653 inifdef = 1+oldfile; 654 } 655 for(i=a;i<=b;i++) { 656 fseek(lb,f[i-1],0); 657 nc = f[i]-f[i-1]; 658 if (opt != D_IFDEF) 659 prints(s); 660 for(j=0;j<nc;j++) 661 putchar(getc(lb)); 662 } 663 if (inifdef && !wantelses) { 664 fprintf(stdout, "#endif %s\n", endifname); 665 inifdef = 0; 666 } 667 } 668 669 #define HALFLONG 16 670 #define low(x) (x&((1L<<HALFLONG)-1)) 671 #define high(x) (x>>HALFLONG) 672 673 /* 674 * hashing has the effect of 675 * arranging line in 7-bit bytes and then 676 * summing 1-s complement in 16-bit hunks 677 */ 678 readhash(f) 679 FILE *f; 680 { 681 long sum; 682 register unsigned shift; 683 register space; 684 register t; 685 sum = 1; 686 space = 0; 687 if(!bflag) for(shift=0;(t=getc(f))!='\n';shift+=7) { 688 if(t==-1) 689 return(0); 690 sum += (long)t << (shift%=HALFLONG); 691 } 692 else for(shift=0;;) { 693 switch(t=getc(f)) { 694 case -1: 695 return(0); 696 case '\t': 697 case ' ': 698 space++; 699 continue; 700 default: 701 if(space) { 702 shift += 7; 703 space = 0; 704 } 705 sum += (long)t << (shift%=HALFLONG); 706 shift += 7; 707 continue; 708 case '\n': 709 break; 710 } 711 break; 712 } 713 sum = low(sum) + high(sum); 714 return((short)low(sum) + (short)high(sum)); 715 } 716