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