lib/diff3.c

   1 /*      $OpenBSD: diff3.c,v 1.41 2016/10/18 21:06:52 millert Exp $      */
   2
   3 /*
   4  * Copyright (C) Caldera International Inc.  2001-2002.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code and documentation must retain the above
  11  *    copyright notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed or owned by Caldera
  18  *      International, Inc.
  19  * 4. Neither the name of Caldera International, Inc. nor the names of other
  20  *    contributors may be used to endorse or promote products derived from
  21  *    this software without specific prior written permission.
  22  *
  23  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
  24  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
  28  * INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  29  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  30  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  32  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  33  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36 /*-
  37  * Copyright (c) 1991, 1993
  38  *      The Regents of the University of California.  All rights reserved.
  39  *
  40  * Redistribution and use in source and binary forms, with or without
  41  * modification, are permitted provided that the following conditions
  42  * are met:
  43  * 1. Redistributions of source code must retain the above copyright
  44  *    notice, this list of conditions and the following disclaimer.
  45  * 2. Redistributions in binary form must reproduce the above copyright
  46  *    notice, this list of conditions and the following disclaimer in the
  47  *    documentation and/or other materials provided with the distribution.
  48  * 3. Neither the name of the University nor the names of its contributors
  49  *    may be used to endorse or promote products derived from this software
  50  *    without specific prior written permission.
  51  *
  52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  62  * SUCH DAMAGE.
  63  *
  64  *      @(#)diff3.c     8.1 (Berkeley) 6/6/93
  65  */
  66
  67 #include "got_compat.h"
  68
  69 #include <sys/stat.h>
  70 #include <sys/queue.h>
  71
  72 #include <ctype.h>
  73 #include <limits.h>
  74 #include <stdio.h>
  75 #include <stdarg.h>
  76 #include <stdlib.h>
  77 #include <string.h>
  78 #include <time.h>
  79 #include <unistd.h>
  80
  81 #include "got_error.h"
  82 #include "got_opentemp.h"
  83 #include "got_object.h"
  84 #include "got_diff.h"
  85
  86 #include "buf.h"
  87 #include "rcsutil.h"
  88 #include "got_lib_diff.h"
  89
  90 #ifndef nitems
  91 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
  92 #endif
  93
  94 /* diff3 - 3-way differential file comparison */
  95
  96 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
  97  *
  98  * d13 = diff report on f1 vs f3
  99  * d23 = diff report on f2 vs f3
 100  * f1, f2, f3 the 3 files
 101  * if changes in f1 overlap with changes in f3, m1 and m3 are used
 102  * to mark the overlaps; otherwise, the file names f1 and f3 are used
 103  * (only for options E and X).
 104  */
 105
 106 /*
 107  * "from" is first in range of changed lines; "to" is last+1
 108  * from=to=line after point of insertion for added lines.
 109  */
 110 struct line_range {
 111         int from;
 112         int to;
 113 };
 114
 115 struct off_range {
 116         off_t from;
 117         off_t to;
 118 };
 119
 120 struct diff {
 121         struct line_range old;
 122         struct line_range new;
 123         struct off_range oldo;
 124         struct off_range newo;
 125 };
 126
 127 struct diff3_state {
 128         size_t szchanges;
 129
 130         struct diff *d13;
 131         struct diff *d23;
 132
 133         /*
 134          * "de" is used to gather editing scripts.  These are later spewed out
 135          * in reverse order.  Its first element must be all zero, the "new"
 136          * component of "de" contains line positions, and "oldo" and "newo"
 137          * components contain byte positions.
 138          * Array overlap indicates which sections in "de" correspond to lines
 139          * that are different in all three files.
 140          */
 141         struct diff *de;
 142         char *overlap;
 143         int overlapcnt;
 144         FILE *fp[3];
 145         int cline[3];           /* # of the last-read line in each file (0-2) */
 146
 147         /*
 148          * the latest known correspondence between line numbers of the 3 files
 149          * is stored in last[1-3];
 150          */
 151         int last[4];
 152         char f1mark[PATH_MAX];
 153         char f2mark[PATH_MAX];
 154         char f3mark[PATH_MAX];
 155
 156         char *buf;
 157
 158         int no_eofnl;           /* set if the merged file has no eof newline */
 159
 160         BUF *diffbuf;
 161 };
 162
 163
 164 static const struct got_error *duplicate(int *, int, struct line_range *,
 165     struct line_range *, struct diff3_state *);
 166 static const struct got_error *edit(struct diff *, int, int *,
 167     struct diff3_state *);
 168 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
 169 static const struct got_error *get_line(char **, FILE *, size_t *,
 170     struct diff3_state *);
 171 static int number(char **);
 172 static const struct got_error *readin(size_t *, char *, struct diff **,
 173     struct diff3_state *);
 174 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
 175 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
 176 static const struct got_error *edscript(int, struct diff3_state *);
 177 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
 178 static const struct got_error *prange(struct line_range *,
 179     struct diff3_state *);
 180 static const struct got_error *repos(int, struct diff3_state *);
 181 static const struct got_error *increase(struct diff3_state *);
 182 static const struct got_error *diff3_internal(char *, char *, char *,
 183     char *, char *, const char *, const char *, struct diff3_state *,
 184     const char *, const char *, const char *);
 185
 186 static const struct got_error *
 187 diff_output(BUF *diffbuf, const char *fmt, ...)
 188 {
 189         const struct got_error *err = NULL;
 190         va_list vap;
 191         int i;
 192         char *str;
 193         size_t newsize;
 194
 195         va_start(vap, fmt);
 196         i = vasprintf(&str, fmt, vap);
 197         va_end(vap);
 198         if (i == -1)
 199                 return got_error_from_errno("vasprintf");
 200         err = buf_append(&newsize, diffbuf, str, strlen(str));
 201         free(str);
 202         return err;
 203 }
 204
 205 static const struct got_error*
 206 diffreg(BUF **d, const char *path1, const char *path2,
 207     enum got_diff_algorithm diff_algo)
 208 {
 209         const struct got_error *err = NULL;
 210         FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
 211         char *outpath = NULL;
 212         struct got_diffreg_result *diffreg_result = NULL;
 213
 214         *d = NULL;
 215
 216         f1 = fopen(path1, "re");
 217         if (f1 == NULL) {
 218                 err = got_error_from_errno2("fopen", path1);
 219                 goto done;
 220         }
 221         f2 = fopen(path2, "re");
 222         if (f1 == NULL) {
 223                 err = got_error_from_errno2("fopen", path2);
 224                 goto done;
 225         }
 226
 227         err = got_opentemp_named(&outpath, &outfile,
 228             GOT_TMPDIR_STR "/got-diffreg", "");
 229         if (err)
 230                 goto done;
 231
 232         err = got_diffreg(&diffreg_result, f1, f2, diff_algo, 0, 0);
 233         if (err)
 234                 goto done;
 235
 236         if (diffreg_result) {
 237                 struct diff_result *diff_result = diffreg_result->result;
 238                 int atomizer_flags = (diff_result->left->atomizer_flags |
 239                     diff_result->right->atomizer_flags);
 240                 if ((atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA)) {
 241                         err = got_error(GOT_ERR_FILE_BINARY);
 242                         goto done;
 243                 }
 244         }
 245
 246         err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
 247             GOT_DIFF_OUTPUT_PLAIN, 0, outfile);
 248         if (err)
 249                 goto done;
 250
 251         if (fflush(outfile) != 0) {
 252                 err = got_error_from_errno2("fflush", outpath);
 253                 goto done;
 254         }
 255         if (fseek(outfile, 0L, SEEK_SET) == -1) {
 256                 err = got_ferror(outfile, GOT_ERR_IO);
 257                 goto done;
 258         }
 259
 260         err = buf_load(d, outfile);
 261 done:
 262         if (outpath) {
 263                 if (unlink(outpath) == -1 && err == NULL)
 264                         err = got_error_from_errno2("unlink", outpath);
 265                 free(outpath);
 266         }
 267         if (outfile && fclose(outfile) == EOF && err == NULL)
 268                 err = got_error_from_errno("fclose");
 269         if (f1 && fclose(f1) == EOF && err == NULL)
 270                 err = got_error_from_errno("fclose");
 271         if (f2 && fclose(f2) == EOF && err == NULL)
 272                 err = got_error_from_errno("fclose");
 273         return err;
 274 }
 275
 276 /*
 277  * For merge(1).
 278  */
 279 const struct got_error *
 280 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
 281     FILE *f3, const char *label1, const char *label2, const char *label3,
 282     enum got_diff_algorithm diff_algo)
 283 {
 284         const struct got_error *err = NULL;
 285         char *dp13, *dp23, *path1, *path2, *path3;
 286         BUF *b1, *b2, *b3, *d1, *d2, *diffb;
 287         u_char *data, *patch;
 288         size_t dlen, plen, i;
 289         struct diff3_state *d3s;
 290
 291         *overlapcnt = 0;
 292
 293         d3s = calloc(1, sizeof(*d3s));
 294         if (d3s == NULL)
 295                 return got_error_from_errno("calloc");
 296
 297         b1 = b2 = b3 = d1 = d2 = diffb = NULL;
 298         dp13 = dp23 = path1 = path2 = path3 = NULL;
 299         data = patch = NULL;
 300
 301         err = buf_load(&b1, f1);
 302         if (err)
 303                 goto out;
 304         err = buf_load(&b2, f2);
 305         if (err)
 306                 goto out;
 307         err = buf_load(&b3, f3);
 308         if (err)
 309                 goto out;
 310
 311         err = buf_alloc(&diffb, 128);
 312         if (err)
 313                 goto out;
 314
 315         if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXXXX") == -1) {
 316                 err = got_error_from_errno("asprintf");
 317                 goto out;
 318         }
 319         if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXXXX") == -1) {
 320                 err = got_error_from_errno("asprintf");
 321                 goto out;
 322         }
 323         if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXXXX") == -1) {
 324                 err = got_error_from_errno("asprintf");
 325                 goto out;
 326         }
 327
 328         err = buf_write_stmp(b1, path1);
 329         if (err)
 330                 goto out;
 331         err = buf_write_stmp(b2, path2);
 332         if (err)
 333                 goto out;
 334         err = buf_write_stmp(b3, path3);
 335         if (err)
 336                 goto out;
 337
 338         buf_free(b2);
 339         b2 = NULL;
 340
 341         err = diffreg(&d1, path1, path3, diff_algo);
 342         if (err) {
 343                 buf_free(diffb);
 344                 diffb = NULL;
 345                 goto out;
 346
 347         }
 348         err = diffreg(&d2, path2, path3, diff_algo);
 349         if (err) {
 350                 buf_free(diffb);
 351                 diffb = NULL;
 352                 goto out;
 353         }
 354
 355         if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
 356                 err = got_error_from_errno("asprintf");
 357                 goto out;
 358         }
 359         err = buf_write_stmp(d1, dp13);
 360         if (err)
 361                 goto out;
 362
 363         buf_free(d1);
 364         d1 = NULL;
 365
 366         if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
 367                 err = got_error_from_errno("asprintf");
 368                 goto out;
 369         }
 370         err = buf_write_stmp(d2, dp23);
 371         if (err)
 372                 goto out;
 373
 374         buf_free(d2);
 375         d2 = NULL;
 376
 377         d3s->diffbuf = diffb;
 378         err = diff3_internal(dp13, dp23, path1, path2, path3,
 379             label1, label3, d3s, label1, label2, label3);
 380         if (err) {
 381                 buf_free(diffb);
 382                 diffb = NULL;
 383                 goto out;
 384         }
 385
 386         plen = buf_len(diffb);
 387         patch = buf_release(diffb);
 388         dlen = buf_len(b1);
 389         data = buf_release(b1);
 390
 391         diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
 392 out:
 393         buf_free(b2);
 394         buf_free(b3);
 395         buf_free(d1);
 396         buf_free(d2);
 397
 398         if (unlink(path1) == -1 && err == NULL)
 399                 err = got_error_from_errno2("unlink", path1);
 400         if (unlink(path2) == -1 && err == NULL)
 401                 err = got_error_from_errno2("unlink", path2);
 402         if (unlink(path3) == -1 && err == NULL)
 403                 err = got_error_from_errno2("unlink", path3);
 404         if (unlink(dp13) == -1 && err == NULL)
 405                 err = got_error_from_errno2("unlink", dp13);
 406         if (unlink(dp23) == -1 && err == NULL)
 407                 err = got_error_from_errno2("unlink", dp23);
 408
 409         free(path1);
 410         free(path2);
 411         free(path3);
 412         free(dp13);
 413         free(dp23);
 414         free(data);
 415         free(patch);
 416
 417         for (i = 0; i < nitems(d3s->fp); i++) {
 418                 if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
 419                         err = got_error_from_errno("fclose");
 420         }
 421         if (err == NULL && diffb) {
 422                 dlen = buf_len(diffb);
 423                 if (d3s->no_eofnl && dlen > 0 &&
 424                     buf_getc(diffb, dlen - 1) == '\n')
 425                         --diffb->cb_len;
 426                 if (buf_write_fd(diffb, outfd) < 0)
 427                         err = got_error_from_errno("buf_write_fd");
 428                 *overlapcnt = d3s->overlapcnt;
 429         }
 430         free(d3s);
 431         buf_free(diffb);
 432         return err;
 433 }
 434
 435 static const struct got_error *
 436 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
 437     const char *fmark, const char *rmark, struct diff3_state *d3s,
 438     const char *label1, const char *label2, const char *label3)
 439 {
 440         const struct got_error *err = NULL;
 441         ssize_t m, n;
 442         int i;
 443
 444         i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
 445             "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
 446             label1 ? " " : "", label1 ? label1 : "");
 447         if (i < 0 || i >= (int)sizeof(d3s->f1mark))
 448                 return got_error(GOT_ERR_NO_SPACE);
 449
 450         i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
 451             "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
 452             label2 ? " " : "", label2 ? label2 : "");
 453         if (i < 0 || i >= (int)sizeof(d3s->f2mark))
 454                 return got_error(GOT_ERR_NO_SPACE);
 455
 456         i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
 457             "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
 458             label3 ? " " : "", label3 ? label3 : "");
 459         if (i < 0 || i >= (int)sizeof(d3s->f3mark))
 460                 return got_error(GOT_ERR_NO_SPACE);
 461
 462         err = increase(d3s);
 463         if (err)
 464                 return err;
 465
 466         err = readin(&m, dp13, &d3s->d13, d3s);
 467         if (err)
 468                 return err;
 469         err = readin(&n, dp23, &d3s->d23, d3s);
 470         if (err)
 471                 return err;
 472
 473         if ((d3s->fp[0] = fopen(path1, "re")) == NULL)
 474                 return got_error_from_errno2("fopen", path1);
 475         if ((d3s->fp[1] = fopen(path2, "re")) == NULL)
 476                 return got_error_from_errno2("fopen", path2);
 477         if ((d3s->fp[2] = fopen(path3, "re")) == NULL)
 478                 return got_error_from_errno2("fopen", path3);
 479
 480         return merge(m, n, d3s);
 481 }
 482
 483 static int
 484 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
 485 {
 486         char op, *ep;
 487         struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
 488         int start, end, i, lineno;
 489         u_char tmp;
 490
 491         dlp = TAILQ_FIRST(&(dlines->l_lines));
 492         lp = TAILQ_FIRST(&(plines->l_lines));
 493
 494         end = 0;
 495         for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
 496             lp = TAILQ_NEXT(lp, l_list)) {
 497                 /* Skip blank lines */
 498                 if (lp->l_len < 2)
 499                         continue;
 500
 501                 /* NUL-terminate line buffer for strtol() safety. */
 502                 tmp = lp->l_line[lp->l_len - 1];
 503                 lp->l_line[lp->l_len - 1] = '\0';
 504
 505                 /* len - 1 is NUL terminator so we use len - 2 for 'op' */
 506                 op = lp->l_line[lp->l_len - 2];
 507                 start = (int)strtol(lp->l_line, &ep, 10);
 508
 509                 /* Restore the last byte of the buffer */
 510                 lp->l_line[lp->l_len - 1] = tmp;
 511
 512                 if (op == 'a') {
 513                         if (start > dlines->l_nblines ||
 514                             start < 0 || *ep != 'a')
 515                                 return -1;
 516                 } else if (op == 'c') {
 517                         if (start > dlines->l_nblines ||
 518                             start < 0 || (*ep != ',' && *ep != 'c'))
 519                                 return -1;
 520
 521                         if (*ep == ',') {
 522                                 ep++;
 523                                 end = (int)strtol(ep, &ep, 10);
 524                                 if (end < 0 || *ep != 'c')
 525                                         return -1;
 526                         } else {
 527                                 end = start;
 528                         }
 529                 }
 530
 531
 532                 for (;;) {
 533                         if (dlp == NULL)
 534                                 break;
 535                         if (dlp->l_lineno == start)
 536                                 break;
 537                         if (dlp->l_lineno > start) {
 538                                 dlp = TAILQ_PREV(dlp, tqh, l_list);
 539                         } else if (dlp->l_lineno < start) {
 540                                 ndlp = TAILQ_NEXT(dlp, l_list);
 541                                 if (ndlp->l_lineno > start)
 542                                         break;
 543                                 dlp = ndlp;
 544                         }
 545                 }
 546
 547                 if (dlp == NULL)
 548                         return -1;
 549
 550
 551                 if (op == 'c') {
 552                         insert_after = TAILQ_PREV(dlp, tqh, l_list);
 553                         for (i = 0; i <= (end - start); i++) {
 554                                 ndlp = TAILQ_NEXT(dlp, l_list);
 555                                 TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
 556                                 dlp = ndlp;
 557                         }
 558                         dlp = insert_after;
 559                 }
 560
 561                 if (op == 'a' || op == 'c') {
 562                         for (;;) {
 563                                 ndlp = lp;
 564                                 lp = TAILQ_NEXT(lp, l_list);
 565                                 if (lp == NULL)
 566                                         return -1;
 567
 568                                 if (lp->l_len == 2 &&
 569                                     lp->l_line[0] == '.' &&
 570                                     lp->l_line[1] == '\n')
 571                                         break;
 572
 573                                 if (lp->l_line[0] == ':') {
 574                                         lp->l_line++;
 575                                         lp->l_len--;
 576                                 }
 577                                 TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
 578                                 TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
 579                                     lp, l_list);
 580                                 dlp = lp;
 581
 582                                 lp->l_lineno = start;
 583                                 lp = ndlp;
 584                         }
 585                 }
 586
 587                 /*
 588                  * always resort lines as the markers might be put at the
 589                  * same line as we first started editing.
 590                  */
 591                 lineno = 0;
 592                 TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
 593                         sort->l_lineno = lineno++;
 594                 dlines->l_nblines = lineno - 1;
 595         }
 596
 597         return (0);
 598 }
 599
 600 /*
 601  * Pick up the line numbers of all changes from one change file.
 602  * (This puts the numbers in a vector, which is not strictly necessary,
 603  * since the vector is processed in one sequential pass.
 604  * The vector could be optimized out of existence)
 605  */
 606 static const struct got_error *
 607 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
 608 {
 609         const struct got_error *err = NULL;
 610         FILE *f;
 611         int a, b, c, d;
 612         char kind, *p;
 613         size_t i = 0;
 614
 615         *n = 0;
 616
 617         f = fopen(name, "re");
 618         if (f == NULL)
 619                 return got_error_from_errno2("fopen", name);
 620         err = getchange(&p, f, d3s);
 621         if (err)
 622                 goto done;
 623         for (i = 0; p; i++) {
 624                 if (i >= d3s->szchanges - 1) {
 625                         err = increase(d3s);
 626                         if (err)
 627                                 goto done;
 628                 }
 629                 a = b = number(&p);
 630                 if (*p == ',') {
 631                         p++;
 632                         b = number(&p);
 633                 }
 634                 kind = *p++;
 635                 c = d = number(&p);
 636                 if (*p == ',') {
 637                         p++;
 638                         d = number(&p);
 639                 }
 640                 if (kind == 'a')
 641                         a++;
 642                 if (kind == 'd')
 643                         c++;
 644                 b++;
 645                 d++;
 646                 (*dd)[i].old.from = a;
 647                 (*dd)[i].old.to = b;
 648                 (*dd)[i].new.from = c;
 649                 (*dd)[i].new.to = d;
 650
 651                 err = getchange(&p, f, d3s);
 652                 if (err)
 653                         goto done;
 654         }
 655
 656         if (i) {
 657                 (*dd)[i].old.from = (*dd)[i - 1].old.to;
 658                 (*dd)[i].new.from = (*dd)[i - 1].new.to;
 659         }
 660 done:
 661         if (fclose(f) == EOF && err == NULL)
 662                 err = got_error_from_errno("fclose");
 663         if (err == NULL)
 664                 *n = i;
 665         return err;
 666 }
 667
 668 static int
 669 number(char **lc)
 670 {
 671         int nn;
 672
 673         nn = 0;
 674         while (isdigit((unsigned char)(**lc)))
 675                 nn = nn*10 + *(*lc)++ - '0';
 676
 677         return (nn);
 678 }
 679
 680 static const struct got_error *
 681 getchange(char **line, FILE *b, struct diff3_state *d3s)
 682 {
 683         const struct got_error *err = NULL;
 684
 685         *line = NULL;
 686         do {
 687                 if (*line && isdigit((unsigned char)(*line)[0]))
 688                         return NULL;
 689                 err = get_line(line, b, NULL, d3s);
 690                 if (err)
 691                         return err;
 692         } while (*line);
 693
 694         return NULL;
 695 }
 696
 697 static const struct got_error *
 698 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
 699 {
 700         const struct got_error *err = NULL;
 701         char *cp = NULL;
 702         size_t size = 0;
 703         ssize_t len;
 704         char *new;
 705
 706         *ret = NULL;
 707         if (n != NULL)
 708                 *n = 0;
 709
 710         len = getline(&cp, &size, b);
 711         if (len == -1) {
 712                 if (ferror(b))
 713                         err = got_error_from_errno("getline");
 714                 goto done;
 715         }
 716
 717         if (cp[len - 1] != '\n') {
 718                 len++;
 719                 if (len + 1 > size) {
 720                         new = realloc(cp, len + 1);
 721                         if (new == NULL) {
 722                                 err = got_error_from_errno("realloc");
 723                                 goto done;
 724                         }
 725                         cp = new;
 726                 }
 727                 cp[len - 1] = '\n';
 728                 cp[len] = '\0';
 729         }
 730
 731         free(d3s->buf);
 732         *ret = d3s->buf = cp;
 733         cp = NULL;
 734         if (n != NULL)
 735                 *n = len;
 736 done:
 737         free(cp);
 738         return err;
 739 }
 740
 741 static const struct got_error *
 742 merge(size_t m1, size_t m2, struct diff3_state *d3s)
 743 {
 744         const struct got_error *err = NULL;
 745         struct diff *d1, *d2;
 746         int dpl, j, t1, t2;
 747
 748         d1 = d3s->d13;
 749         d2 = d3s->d23;
 750         j = 0;
 751         for (;;) {
 752                 t1 = (d1 < d3s->d13 + m1);
 753                 t2 = (d2 < d3s->d23 + m2);
 754                 if (!t1 && !t2)
 755                         break;
 756
 757                 /* first file is different from others */
 758                 if (!t2 || (t1 && d1->new.to < d2->new.from)) {
 759                         /* stuff peculiar to 1st file */
 760                         d1++;
 761                         continue;
 762                 }
 763
 764                 /* second file is different from others */
 765                 if (!t1 || (t2 && d2->new.to < d1->new.from)) {
 766                         d2++;
 767                         continue;
 768                 }
 769
 770                 /*
 771                  * Merge overlapping changes in first file
 772                  * this happens after extension (see below).
 773                  */
 774                 if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
 775                         d1[1].old.from = d1->old.from;
 776                         d1[1].new.from = d1->new.from;
 777                         d1++;
 778                         continue;
 779                 }
 780
 781                 /* merge overlapping changes in second */
 782                 if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
 783                         d2[1].old.from = d2->old.from;
 784                         d2[1].new.from = d2->new.from;
 785                         d2++;
 786                         continue;
 787                 }
 788                 /* stuff peculiar to third file or different in all */
 789                 if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
 790                         err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
 791                         if (err)
 792                                 return err;
 793
 794                         /*
 795                          * dpl = 0 means all files differ
 796                          * dpl = 1 means files 1 and 2 identical
 797                          */
 798                         err = edit(d1, dpl, &j, d3s);
 799                         if (err)
 800                                 return err;
 801                         d1++;
 802                         d2++;
 803                         continue;
 804                 }
 805
 806                 /*
 807                  * Overlapping changes from file 1 and 2; extend changes
 808                  * appropriately to make them coincide.
 809                  */
 810                 if (d1->new.from < d2->new.from) {
 811                         d2->old.from -= d2->new.from - d1->new.from;
 812                         d2->new.from = d1->new.from;
 813                 } else if (d2->new.from < d1->new.from) {
 814                         d1->old.from -= d1->new.from - d2->new.from;
 815                         d1->new.from = d2->new.from;
 816                 }
 817                 if (d1->new.to > d2->new.to) {
 818                         d2->old.to += d1->new.to - d2->new.to;
 819                         d2->new.to = d1->new.to;
 820                 } else if (d2->new.to > d1->new.to) {
 821                         d1->old.to += d2->new.to - d1->new.to;
 822                         d1->new.to = d2->new.to;
 823                 }
 824         }
 825
 826         return (edscript(j, d3s));
 827 }
 828
 829 /*
 830  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
 831  */
 832 static const struct got_error *
 833 prange(struct line_range *rold, struct diff3_state *d3s)
 834 {
 835         const struct got_error *err = NULL;
 836
 837         if (rold->to <= rold->from) {
 838                 err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
 839                 if (err)
 840                         return err;
 841         } else {
 842                 err = diff_output(d3s->diffbuf, "%d", rold->from);
 843                 if (err)
 844                         return err;
 845                 if (rold->to > rold->from + 1) {
 846                         err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
 847                         if (err)
 848                                 return err;
 849                 }
 850                 err = diff_output(d3s->diffbuf, "c\n");
 851                 if (err)
 852                         return err;
 853         }
 854
 855         return NULL;
 856 }
 857
 858 /*
 859  * Skip to just before line number from in file "i".
 860  * Return the number of bytes skipped in *nskipped.
 861  */
 862 static const struct got_error *
 863 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
 864 {
 865         const struct got_error *err = NULL;
 866         size_t len, n;
 867         char *line;
 868
 869         *nskipped = 0;
 870         for (n = 0; d3s->cline[i] < from - 1; n += len) {
 871                 err = get_line(&line, d3s->fp[i], &len, d3s);
 872                 if (err)
 873                         return err;
 874                 d3s->cline[i]++;
 875         }
 876         *nskipped = n;
 877         return NULL;
 878 }
 879
 880 /*
 881  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
 882  * the same data as the new range (in file 2).
 883  *
 884  * If this change could overlap, remember start/end offsets in file 2 so we
 885  * can write out the original lines of text if a merge conflict occurs.
 886  */
 887 static const struct got_error *
 888 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
 889     struct diff3_state *d3s)
 890 {
 891         const struct got_error *err = NULL;
 892         int c,d;
 893         int nchar;
 894         int nline;
 895         size_t nskipped;
 896         off_t off;
 897
 898         *dpl = 0;
 899
 900         if (r1->to - r1->from != r2->to - r2->from)
 901                 return NULL;
 902
 903         err = skip(&nskipped, 0, r1->from, d3s);
 904         if (err)
 905                 return err;
 906         err = skip(&nskipped, 1, r2->from, d3s);
 907         if (err)
 908                 return err;
 909
 910         off = ftello(d3s->fp[1]);
 911         if (off == -1)
 912                 return got_error_from_errno("ftello");
 913         d3s->de[j + 1].oldo.from = off; /* original lines start here */
 914
 915         nchar = 0;
 916         for (nline = 0; nline < r1->to - r1->from; nline++) {
 917                 do {
 918                         c = getc(d3s->fp[0]);
 919                         d = getc(d3s->fp[1]);
 920                         if (c == EOF && d == EOF)
 921                                 break;
 922                         else if (c == EOF)
 923                                 return got_ferror(d3s->fp[0], GOT_ERR_EOF);
 924                         else if (d == EOF)
 925                                 return got_ferror(d3s->fp[1], GOT_ERR_EOF);
 926                         nchar++;
 927                         if (c != d) {
 928                                 long orig_line_len = nchar;
 929                                 while (d != '\n') {
 930                                         d = getc(d3s->fp[1]);
 931                                         if (d == EOF)
 932                                                 break;
 933                                         orig_line_len++;
 934                                 }
 935                                 if (orig_line_len > nchar &&
 936                                     fseek(d3s->fp[1], -(orig_line_len - nchar),
 937                                     SEEK_CUR) == -1)
 938                                         return got_ferror(d3s->fp[1],
 939                                                 GOT_ERR_IO);
 940                                 /* original lines end here */
 941                                 d3s->de[j + 1].oldo.to = off + orig_line_len;
 942                                 err = repos(nchar, d3s);
 943                                 if (err)
 944                                         return err;
 945                                 return NULL;
 946                         }
 947                 } while (c != '\n');
 948         }
 949
 950         /* original lines end here */
 951         d3s->de[j + 1].oldo.to = off + nchar;
 952
 953         err = repos(nchar, d3s);
 954         if (err)
 955                 return err;
 956         *dpl = 1;
 957         return NULL;
 958 }
 959
 960 static const struct got_error *
 961 repos(int nchar, struct diff3_state *d3s)
 962 {
 963         int i;
 964
 965         for (i = 0; i < 2; i++) {
 966                 if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
 967                         return got_ferror(d3s->fp[i], GOT_ERR_IO);
 968         }
 969
 970         return NULL;
 971 }
 972
 973 /*
 974  * collect an editing script for later regurgitation
 975  */
 976 static const struct got_error *
 977 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
 978 {
 979         const struct got_error *err = NULL;
 980         size_t nskipped;
 981
 982         if (((fdup + 1) & 3) == 0)
 983                 return NULL;
 984         (*j)++;
 985         d3s->overlap[*j] = !fdup;
 986         if (!fdup)
 987                 d3s->overlapcnt++;
 988         d3s->de[*j].old.from = diff->old.from;
 989         d3s->de[*j].old.to = diff->old.to;
 990
 991         err = skip(&nskipped, 2, diff->new.from, d3s);
 992         if (err)
 993                 return err;
 994         d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
 995
 996         err = skip(&nskipped, 2, diff->new.to, d3s);
 997         if (err)
 998                 return err;
 999         d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
1000         return NULL;
1001 }
1002
1003 /* regurgitate */
1004 static const struct got_error *
1005 edscript(int n, struct diff3_state *d3s)
1006 {
1007         const struct got_error *err = NULL;
1008         off_t len;
1009         char *line = NULL;
1010         size_t linesize = 0;
1011         ssize_t linelen = 0, k;
1012
1013         for (; n > 0; n--) {
1014                 if (!d3s->overlap[n]) {
1015                         err = prange(&d3s->de[n].old, d3s);
1016                         if (err)
1017                                 return err;
1018                 } else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
1019                         /* Output a block of 3-way diff base file content. */
1020                         err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1021                             d3s->de[n].old.to - 1, d3s->f2mark);
1022                         if (err)
1023                                 return err;
1024                         if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1025                             == -1)
1026                                 return got_error_from_errno("fseeko");
1027                         len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1028                         for (k = 0; k < (ssize_t)len; k += linelen) {
1029                                 linelen = getline(&line, &linesize, d3s->fp[1]);
1030                                 if (linelen == -1) {
1031                                         if (feof(d3s->fp[1]))
1032                                                 break;
1033                                         err = got_ferror(d3s->fp[1],
1034                                             GOT_ERR_IO);
1035                                         goto done;
1036                                 }
1037                                 err = diff_output(d3s->diffbuf, ":%s", line);
1038                                 if (err)
1039                                         goto done;
1040                         }
1041                         err = diff_output(d3s->diffbuf, "%s%s\n",
1042                             linelen > 0 && line[linelen] == '\n' ? ":" : "",
1043                             GOT_DIFF_CONFLICT_MARKER_SEP);
1044                         if (err)
1045                                 goto done;
1046                 } else {
1047                         err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1048                             d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1049                         if (err)
1050                                 goto done;
1051                 }
1052                 if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1053                     == -1) {
1054                         err = got_error_from_errno("fseek");
1055                         goto done;
1056                 }
1057                 len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1058                 for (k = 0; k < (ssize_t)len; k += linelen) {
1059                         linelen = getline(&line, &linesize, d3s->fp[2]);
1060                         if (linelen == -1) {
1061                                 if (feof(d3s->fp[2]))
1062                                         break;
1063                                 err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1064                                 goto done;
1065                         }
1066                         err = diff_output(d3s->diffbuf, ":%s", line);
1067                         if (err)
1068                                 goto done;
1069                 }
1070
1071                 if (!d3s->overlap[n]) {
1072                         size_t len;
1073
1074                         len = buf_len(d3s->diffbuf);
1075                         if (len > 0) {
1076                                 if (buf_getc(d3s->diffbuf, len - 1) != '\n') {
1077                                         err = buf_putc(d3s->diffbuf, '\n');
1078                                         if (err != NULL)
1079                                                 goto done;
1080                                         d3s->no_eofnl = 1;
1081                                 }
1082                         }
1083                         err = diff_output(d3s->diffbuf, ".\n");
1084                         if (err)
1085                                 goto done;
1086                 } else {
1087                         err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1088                             linelen > 0 && line[linelen] == '\n' ? ":" : "",
1089                             d3s->f3mark);
1090                         if (err)
1091                                 goto done;
1092                         err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1093                             d3s->de[n].old.from - 1, d3s->f1mark);
1094                         if (err)
1095                                 goto done;
1096                 }
1097         }
1098 done:
1099         free(line);
1100         return err;
1101 }
1102
1103 static const struct got_error *
1104 increase(struct diff3_state *d3s)
1105 {
1106         size_t newsz, incr;
1107         struct diff *d;
1108         char *s;
1109
1110         /* are the memset(3) calls needed? */
1111         newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1112         incr = newsz - d3s->szchanges;
1113
1114         d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1115         if (d == NULL)
1116                 return got_error_from_errno("reallocarray");
1117         d3s->d13 = d;
1118         memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1119
1120         d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1121         if (d == NULL)
1122                 return got_error_from_errno("reallocarray");
1123         d3s->d23 = d;
1124         memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1125
1126         d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1127         if (d == NULL)
1128                 return got_error_from_errno("reallocarray");
1129         d3s->de = d;
1130         memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1131
1132         s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1133         if (s == NULL)
1134                 return got_error_from_errno("reallocarray");
1135         d3s->overlap = s;
1136         memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1137         d3s->szchanges = newsz;
1138
1139         return NULL;
1140 }