usr.bin/diff/diff.c

   1 /*      $OpenBSD: diff.c,v 1.67 2019/06/28 13:35:00 deraadt Exp $       */
   2
   3 /*
   4  * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  *
  18  * Sponsored in part by the Defense Advanced Research Projects
  19  * Agency (DARPA) and Air Force Research Laboratory, Air Force
  20  * Materiel Command, USAF, under agreement number F39502-99-1-0512.
  21  */
  22
  23 #include <sys/cdefs.h>
  24 #include <sys/stat.h>
  25
  26 #include <ctype.h>
  27 #include <err.h>
  28 #include <errno.h>
  29 #include <getopt.h>
  30 #include <stdlib.h>
  31 #include <stdio.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <limits.h>
  35
  36 #include "diff.h"
  37 #include "xmalloc.h"
  38
  39 static const char diff_version[] = "FreeBSD diff 20220309";
  40 bool     lflag, Nflag, Pflag, rflag, sflag, Tflag, cflag;
  41 bool     ignore_file_case, suppress_common, color, noderef;
  42 static bool help = false;
  43 int      diff_format, diff_context, status;
  44 int      tabsize = 8, width = 130;
  45 static int      colorflag = COLORFLAG_NEVER;
  46 char    *start, *ifdefname, *diffargs, *label[2];
  47 char    *ignore_pats, *most_recent_pat;
  48 char    *group_format = NULL;
  49 const char      *add_code, *del_code;
  50 struct stat stb1, stb2;
  51 struct excludes *excludes_list;
  52 regex_t  ignore_re, most_recent_re;
  53
  54 #define OPTIONS "0123456789aBbC:cdD:efF:HhI:iL:lnNPpqrS:sTtU:uwW:X:x:y"
  55 enum {
  56         OPT_TSIZE = CHAR_MAX + 1,
  57         OPT_STRIPCR,
  58         OPT_IGN_FN_CASE,
  59         OPT_NO_IGN_FN_CASE,
  60         OPT_NORMAL,
  61         OPT_HELP,
  62         OPT_HORIZON_LINES,
  63         OPT_CHANGED_GROUP_FORMAT,
  64         OPT_SUPPRESS_COMMON,
  65         OPT_COLOR,
  66         OPT_NO_DEREFERENCE,
  67         OPT_VERSION,
  68 };
  69
  70 static struct option longopts[] = {
  71         { "text",                       no_argument,            0,      'a' },
  72         { "ignore-space-change",        no_argument,            0,      'b' },
  73         { "context",                    optional_argument,      0,      'C' },
  74         { "ifdef",                      required_argument,      0,      'D' },
  75         { "minimal",                    no_argument,            0,      'd' },
  76         { "ed",                         no_argument,            0,      'e' },
  77         { "forward-ed",                 no_argument,            0,      'f' },
  78         { "show-function-line",         required_argument,      0,      'F' },
  79         { "speed-large-files",          no_argument,            NULL,   'H' },
  80         { "ignore-blank-lines",         no_argument,            0,      'B' },
  81         { "ignore-matching-lines",      required_argument,      0,      'I' },
  82         { "ignore-case",                no_argument,            0,      'i' },
  83         { "paginate",                   no_argument,            NULL,   'l' },
  84         { "label",                      required_argument,      0,      'L' },
  85         { "new-file",                   no_argument,            0,      'N' },
  86         { "rcs",                        no_argument,            0,      'n' },
  87         { "unidirectional-new-file",    no_argument,            0,      'P' },
  88         { "show-c-function",            no_argument,            0,      'p' },
  89         { "brief",                      no_argument,            0,      'q' },
  90         { "recursive",                  no_argument,            0,      'r' },
  91         { "report-identical-files",     no_argument,            0,      's' },
  92         { "starting-file",              required_argument,      0,      'S' },
  93         { "expand-tabs",                no_argument,            0,      't' },
  94         { "initial-tab",                no_argument,            0,      'T' },
  95         { "unified",                    optional_argument,      0,      'U' },
  96         { "ignore-all-space",           no_argument,            0,      'w' },
  97         { "width",                      required_argument,      0,      'W' },
  98         { "exclude",                    required_argument,      0,      'x' },
  99         { "exclude-from",               required_argument,      0,      'X' },
 100         { "side-by-side",               no_argument,            NULL,   'y' },
 101         { "ignore-file-name-case",      no_argument,            NULL,   OPT_IGN_FN_CASE },
 102         { "help",                       no_argument,            NULL,   OPT_HELP},
 103         { "horizon-lines",              required_argument,      NULL,   OPT_HORIZON_LINES },
 104         { "no-dereference",             no_argument,            NULL,   OPT_NO_DEREFERENCE},
 105         { "no-ignore-file-name-case",   no_argument,            NULL,   OPT_NO_IGN_FN_CASE },
 106         { "normal",                     no_argument,            NULL,   OPT_NORMAL },
 107         { "strip-trailing-cr",          no_argument,            NULL,   OPT_STRIPCR },
 108         { "tabsize",                    required_argument,      NULL,   OPT_TSIZE },
 109         { "changed-group-format",       required_argument,      NULL,   OPT_CHANGED_GROUP_FORMAT},
 110         { "suppress-common-lines",      no_argument,            NULL,   OPT_SUPPRESS_COMMON },
 111         { "color",                      optional_argument,      NULL,   OPT_COLOR },
 112         { "version",                    no_argument,            NULL,   OPT_VERSION},
 113         { NULL,                         0,                      0,      '\0'}
 114 };
 115
 116 static void checked_regcomp(char const *, regex_t *);
 117 static void usage(void) __dead2;
 118 static void conflicting_format(void) __dead2;
 119 static void push_excludes(char *);
 120 static void push_ignore_pats(char *);
 121 static void read_excludes_file(char *file);
 122 static void set_argstr(char **, char **);
 123 static char *splice(char *, char *);
 124 static bool do_color(void);
 125
 126 int
 127 main(int argc, char **argv)
 128 {
 129         const char *errstr = NULL;
 130         char *ep, **oargv;
 131         long  l;
 132         int   ch, dflags, lastch, gotstdin, prevoptind, newarg;
 133
 134         oargv = argv;
 135         gotstdin = 0;
 136         dflags = 0;
 137         lastch = '\0';
 138         prevoptind = 1;
 139         newarg = 1;
 140         diff_context = 3;
 141         diff_format = D_UNSET;
 142 #define FORMAT_MISMATCHED(type) \
 143         (diff_format != D_UNSET && diff_format != (type))
 144         while ((ch = getopt_long(argc, argv, OPTIONS, longopts, NULL)) != -1) {
 145                 switch (ch) {
 146                 case '0': case '1': case '2': case '3': case '4':
 147                 case '5': case '6': case '7': case '8': case '9':
 148                         if (newarg)
 149                                 usage();        /* disallow -[0-9]+ */
 150                         else if (lastch == 'c' || lastch == 'u')
 151                                 diff_context = 0;
 152                         else if (!isdigit(lastch) || diff_context > INT_MAX / 10)
 153                                 usage();
 154                         diff_context = (diff_context * 10) + (ch - '0');
 155                         break;
 156                 case 'a':
 157                         dflags |= D_FORCEASCII;
 158                         break;
 159                 case 'b':
 160                         dflags |= D_FOLDBLANKS;
 161                         break;
 162                 case 'C':
 163                 case 'c':
 164                         if (FORMAT_MISMATCHED(D_CONTEXT))
 165                                 conflicting_format();
 166                         cflag = true;
 167                         diff_format = D_CONTEXT;
 168                         if (optarg != NULL) {
 169                                 l = strtol(optarg, &ep, 10);
 170                                 if (*ep != '\0' || l < 0 || l >= INT_MAX)
 171                                         usage();
 172                                 diff_context = (int)l;
 173                         }
 174                         break;
 175                 case 'd':
 176                         dflags |= D_MINIMAL;
 177                         break;
 178                 case 'D':
 179                         if (FORMAT_MISMATCHED(D_IFDEF))
 180                                 conflicting_format();
 181                         diff_format = D_IFDEF;
 182                         ifdefname = optarg;
 183                         break;
 184                 case 'e':
 185                         if (FORMAT_MISMATCHED(D_EDIT))
 186                                 conflicting_format();
 187                         diff_format = D_EDIT;
 188                         break;
 189                 case 'f':
 190                         if (FORMAT_MISMATCHED(D_REVERSE))
 191                                 conflicting_format();
 192                         diff_format = D_REVERSE;
 193                         break;
 194                 case 'H':
 195                         /* ignore but needed for compatibility with GNU diff */
 196                         break;
 197                 case 'h':
 198                         /* silently ignore for backwards compatibility */
 199                         break;
 200                 case 'B':
 201                         dflags |= D_SKIPBLANKLINES;
 202                         break;
 203                 case 'F':
 204                         if (dflags & D_PROTOTYPE)
 205                                 conflicting_format();
 206                         dflags |= D_MATCHLAST;
 207                         most_recent_pat = xstrdup(optarg);
 208                         break;
 209                 case 'I':
 210                         push_ignore_pats(optarg);
 211                         break;
 212                 case 'i':
 213                         dflags |= D_IGNORECASE;
 214                         break;
 215                 case 'L':
 216                         if (label[0] == NULL)
 217                                 label[0] = optarg;
 218                         else if (label[1] == NULL)
 219                                 label[1] = optarg;
 220                         else
 221                                 usage();
 222                         break;
 223                 case 'l':
 224                         lflag = true;
 225                         break;
 226                 case 'N':
 227                         Nflag = true;
 228                         break;
 229                 case 'n':
 230                         if (FORMAT_MISMATCHED(D_NREVERSE))
 231                                 conflicting_format();
 232                         diff_format = D_NREVERSE;
 233                         break;
 234                 case 'p':
 235                         if (dflags & D_MATCHLAST)
 236                                 conflicting_format();
 237                         dflags |= D_PROTOTYPE;
 238                         break;
 239                 case 'P':
 240                         Pflag = true;
 241                         break;
 242                 case 'r':
 243                         rflag = true;
 244                         break;
 245                 case 'q':
 246                         if (FORMAT_MISMATCHED(D_BRIEF))
 247                                 conflicting_format();
 248                         diff_format = D_BRIEF;
 249                         break;
 250                 case 'S':
 251                         start = optarg;
 252                         break;
 253                 case 's':
 254                         sflag = true;
 255                         break;
 256                 case 'T':
 257                         Tflag = true;
 258                         break;
 259                 case 't':
 260                         dflags |= D_EXPANDTABS;
 261                         break;
 262                 case 'U':
 263                 case 'u':
 264                         if (FORMAT_MISMATCHED(D_UNIFIED))
 265                                 conflicting_format();
 266                         diff_format = D_UNIFIED;
 267                         if (optarg != NULL) {
 268                                 l = strtol(optarg, &ep, 10);
 269                                 if (*ep != '\0' || l < 0 || l >= INT_MAX)
 270                                         usage();
 271                                 diff_context = (int)l;
 272                         }
 273                         break;
 274                 case 'w':
 275                         dflags |= D_IGNOREBLANKS;
 276                         break;
 277                 case 'W':
 278                         width = (int) strtonum(optarg, 1, INT_MAX, &errstr);
 279                         if (errstr) {
 280                                 warnx("Invalid argument for width");
 281                                 usage();
 282                         }
 283                         break;
 284                 case 'X':
 285                         read_excludes_file(optarg);
 286                         break;
 287                 case 'x':
 288                         push_excludes(optarg);
 289                         break;
 290                 case 'y':
 291                         if (FORMAT_MISMATCHED(D_SIDEBYSIDE))
 292                                 conflicting_format();
 293                         diff_format = D_SIDEBYSIDE;
 294                         break;
 295                 case OPT_CHANGED_GROUP_FORMAT:
 296                         if (FORMAT_MISMATCHED(D_GFORMAT))
 297                                 conflicting_format();
 298                         diff_format = D_GFORMAT;
 299                         group_format = optarg;
 300                         break;
 301                 case OPT_HELP:
 302                         help = true;
 303                         usage();
 304                         break;
 305                 case OPT_HORIZON_LINES:
 306                         break; /* XXX TODO for compatibility with GNU diff3 */
 307                 case OPT_IGN_FN_CASE:
 308                         ignore_file_case = true;
 309                         break;
 310                 case OPT_NO_IGN_FN_CASE:
 311                         ignore_file_case = false;
 312                         break;
 313                 case OPT_NORMAL:
 314                         if (FORMAT_MISMATCHED(D_NORMAL))
 315                                 conflicting_format();
 316                         diff_format = D_NORMAL;
 317                         break;
 318                 case OPT_TSIZE:
 319                         tabsize = (int) strtonum(optarg, 1, INT_MAX, &errstr);
 320                         if (errstr) {
 321                                 warnx("Invalid argument for tabsize");
 322                                 usage();
 323                         }
 324                         break;
 325                 case OPT_STRIPCR:
 326                         dflags |= D_STRIPCR;
 327                         break;
 328                 case OPT_SUPPRESS_COMMON:
 329                         suppress_common = 1;
 330                         break;
 331                 case OPT_COLOR:
 332                         if (optarg == NULL || strncmp(optarg, "auto", 4) == 0)
 333                                 colorflag = COLORFLAG_AUTO;
 334                         else if (strncmp(optarg, "always", 6) == 0)
 335                                 colorflag = COLORFLAG_ALWAYS;
 336                         else if (strncmp(optarg, "never", 5) == 0)
 337                                 colorflag = COLORFLAG_NEVER;
 338                         else
 339                                 errx(2, "unsupported --color value '%s' (must be always, auto, or never)",
 340                                         optarg);
 341                         break;
 342                 case OPT_NO_DEREFERENCE:
 343                         rflag = true;
 344                         noderef = true;
 345                         break;
 346                 case OPT_VERSION:
 347                         printf("%s\n", diff_version);
 348                         exit(0);
 349                 default:
 350                         usage();
 351                         break;
 352                 }
 353                 lastch = ch;
 354                 newarg = optind != prevoptind;
 355                 prevoptind = optind;
 356         }
 357         if (diff_format == D_UNSET && (dflags & D_PROTOTYPE) != 0)
 358                 diff_format = D_CONTEXT;
 359         if (diff_format == D_UNSET)
 360                 diff_format = D_NORMAL;
 361         argc -= optind;
 362         argv += optind;
 363
 364         if (do_color()) {
 365                 char *p;
 366                 const char *env;
 367
 368                 color = true;
 369                 add_code = "32";
 370                 del_code = "31";
 371                 env = getenv("DIFFCOLORS");
 372                 if (env != NULL && *env != '\0' && (p = strdup(env))) {
 373                         add_code = p;
 374                         strsep(&p, ":");
 375                         if (p != NULL)
 376                                 del_code = p;
 377                 }
 378         }
 379
 380 #ifdef __OpenBSD__
 381         if (pledge("stdio rpath tmppath", NULL) == -1)
 382                 err(2, "pledge");
 383 #endif
 384
 385         /*
 386          * Do sanity checks, fill in stb1 and stb2 and call the appropriate
 387          * driver routine.  Both drivers use the contents of stb1 and stb2.
 388          */
 389         if (argc != 2)
 390                 usage();
 391         checked_regcomp(ignore_pats, &ignore_re);
 392         checked_regcomp(most_recent_pat, &most_recent_re);
 393         if (strcmp(argv[0], "-") == 0) {
 394                 fstat(STDIN_FILENO, &stb1);
 395                 gotstdin = 1;
 396         } else if (stat(argv[0], &stb1) != 0) {
 397                 if (!Nflag || errno != ENOENT)
 398                         err(2, "%s", argv[0]);
 399                 dflags |= D_EMPTY1;
 400                 memset(&stb1, 0, sizeof(struct stat));
 401         }
 402
 403         if (strcmp(argv[1], "-") == 0) {
 404                 fstat(STDIN_FILENO, &stb2);
 405                 gotstdin = 1;
 406         } else if (stat(argv[1], &stb2) != 0) {
 407                 if (!Nflag || errno != ENOENT)
 408                         err(2, "%s", argv[1]);
 409                 dflags |= D_EMPTY2;
 410                 memset(&stb2, 0, sizeof(stb2));
 411                 stb2.st_mode = stb1.st_mode;
 412         }
 413
 414         if (dflags & D_EMPTY1 && dflags & D_EMPTY2){
 415                 warn("%s", argv[0]);
 416                 warn("%s", argv[1]);
 417                 exit(2);
 418         }
 419
 420         if (stb1.st_mode == 0)
 421                 stb1.st_mode = stb2.st_mode;
 422
 423         if (gotstdin && (S_ISDIR(stb1.st_mode) || S_ISDIR(stb2.st_mode)))
 424                 errx(2, "can't compare - to a directory");
 425         set_argstr(oargv, argv);
 426         if (S_ISDIR(stb1.st_mode) && S_ISDIR(stb2.st_mode)) {
 427                 if (diff_format == D_IFDEF)
 428                         errx(2, "-D option not supported with directories");
 429                 diffdir(argv[0], argv[1], dflags);
 430         } else {
 431                 if (S_ISDIR(stb1.st_mode)) {
 432                         argv[0] = splice(argv[0], argv[1]);
 433                         if (stat(argv[0], &stb1) == -1)
 434                                 err(2, "%s", argv[0]);
 435                 }
 436                 if (S_ISDIR(stb2.st_mode)) {
 437                         argv[1] = splice(argv[1], argv[0]);
 438                         if (stat(argv[1], &stb2) == -1)
 439                                 err(2, "%s", argv[1]);
 440                 }
 441                 print_status(diffreg(argv[0], argv[1], dflags, 1), argv[0],
 442                     argv[1], "");
 443         }
 444         exit(status);
 445 }
 446
 447 static void
 448 checked_regcomp(char const *pattern, regex_t *comp)
 449 {
 450         char buf[BUFSIZ];
 451         int error;
 452
 453         if (pattern == NULL)
 454                 return;
 455
 456         error = regcomp(comp, pattern, REG_NEWLINE | REG_EXTENDED);
 457         if (error != 0) {
 458                 regerror(error, comp, buf, sizeof(buf));
 459                 if (*pattern != '\0')
 460                         errx(2, "%s: %s", pattern, buf);
 461                 else
 462                         errx(2, "%s", buf);
 463         }
 464 }
 465
 466 static void
 467 set_argstr(char **av, char **ave)
 468 {
 469         size_t argsize;
 470         char **ap;
 471
 472         argsize = 4 + *ave - *av + 1;
 473         diffargs = xmalloc(argsize);
 474         strlcpy(diffargs, "diff", argsize);
 475         for (ap = av + 1; ap < ave; ap++) {
 476                 if (strcmp(*ap, "--") != 0) {
 477                         strlcat(diffargs, " ", argsize);
 478                         strlcat(diffargs, *ap, argsize);
 479                 }
 480         }
 481 }
 482
 483 /*
 484  * Read in an excludes file and push each line.
 485  */
 486 static void
 487 read_excludes_file(char *file)
 488 {
 489         FILE *fp;
 490         char *buf, *pattern;
 491         size_t len;
 492
 493         if (strcmp(file, "-") == 0)
 494                 fp = stdin;
 495         else if ((fp = fopen(file, "r")) == NULL)
 496                 err(2, "%s", file);
 497         while ((buf = fgetln(fp, &len)) != NULL) {
 498                 if (buf[len - 1] == '\n')
 499                         len--;
 500                 if ((pattern = strndup(buf, len)) == NULL)
 501                         err(2, "xstrndup");
 502                 push_excludes(pattern);
 503         }
 504         if (strcmp(file, "-") != 0)
 505                 fclose(fp);
 506 }
 507
 508 /*
 509  * Push a pattern onto the excludes list.
 510  */
 511 static void
 512 push_excludes(char *pattern)
 513 {
 514         struct excludes *entry;
 515
 516         entry = xmalloc(sizeof(*entry));
 517         entry->pattern = pattern;
 518         entry->next = excludes_list;
 519         excludes_list = entry;
 520 }
 521
 522 static void
 523 push_ignore_pats(char *pattern)
 524 {
 525         size_t len;
 526
 527         if (ignore_pats == NULL)
 528                 ignore_pats = xstrdup(pattern);
 529         else {
 530                 /* old + "|" + new + NUL */
 531                 len = strlen(ignore_pats) + strlen(pattern) + 2;
 532                 ignore_pats = xreallocarray(ignore_pats, 1, len);
 533                 strlcat(ignore_pats, "|", len);
 534                 strlcat(ignore_pats, pattern, len);
 535         }
 536 }
 537
 538 void
 539 print_status(int val, char *path1, char *path2, const char *entry)
 540 {
 541         if (label[0] != NULL)
 542                 path1 = label[0];
 543         if (label[1] != NULL)
 544                 path2 = label[1];
 545
 546         switch (val) {
 547         case D_BINARY:
 548                 printf("Binary files %s%s and %s%s differ\n",
 549                     path1, entry, path2, entry);
 550                 break;
 551         case D_DIFFER:
 552                 if (diff_format == D_BRIEF)
 553                         printf("Files %s%s and %s%s differ\n",
 554                             path1, entry, path2, entry);
 555                 break;
 556         case D_SAME:
 557                 if (sflag)
 558                         printf("Files %s%s and %s%s are identical\n",
 559                             path1, entry, path2, entry);
 560                 break;
 561         case D_MISMATCH1:
 562                 printf("File %s%s is a directory while file %s%s is a regular file\n",
 563                     path1, entry, path2, entry);
 564                 break;
 565         case D_MISMATCH2:
 566                 printf("File %s%s is a regular file while file %s%s is a directory\n",
 567                     path1, entry, path2, entry);
 568                 break;
 569         case D_SKIPPED1:
 570                 printf("File %s%s is not a regular file or directory and was skipped\n",
 571                     path1, entry);
 572                 break;
 573         case D_SKIPPED2:
 574                 printf("File %s%s is not a regular file or directory and was skipped\n",
 575                     path2, entry);
 576                 break;
 577         case D_ERROR:
 578                 break;
 579         }
 580 }
 581
 582 static void
 583 usage(void)
 584 {
 585         (void)fprintf(help ? stdout : stderr,
 586             "usage: diff [-aBbdilpTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
 587             "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
 588             "            [-I pattern] [-F pattern] [-L label] file1 file2\n"
 589             "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
 590             "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
 591             "            [-F pattern] -C number file1 file2\n"
 592             "       diff [-aBbdiltw] [-I pattern] [--ignore-case] [--no-ignore-case]\n"
 593             "            [--normal] [--strip-trailing-cr] [--tabsize] -D string file1 file2\n"
 594             "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
 595             "            [--no-ignore-case] [--normal] [--tabsize] [--strip-trailing-cr]\n"
 596             "            [-F pattern] -U number file1 file2\n"
 597             "       diff [-aBbdilNPprsTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
 598             "            [--no-ignore-case] [--normal] [--tabsize] [-I pattern] [-L label]\n"
 599             "            [-F pattern] [-S name] [-X file] [-x pattern] dir1 dir2\n"
 600             "       diff [-aBbditwW] [--expand-tabs] [--ignore-all-blanks]\n"
 601             "            [--ignore-blank-lines] [--ignore-case] [--minimal]\n"
 602             "            [--no-ignore-file-name-case] [--strip-trailing-cr]\n"
 603             "            [--suppress-common-lines] [--tabsize] [--text] [--width]\n"
 604             "            -y | --side-by-side file1 file2\n"
 605             "       diff [--help] [--version]\n");
 606
 607         if (help)
 608                 exit(0);
 609         else
 610                 exit(2);
 611 }
 612
 613 static void
 614 conflicting_format(void)
 615 {
 616
 617         fprintf(stderr, "error: conflicting output format options.\n");
 618         usage();
 619 }
 620
 621 static bool
 622 do_color(void)
 623 {
 624         const char *p, *p2;
 625
 626         switch (colorflag) {
 627         case COLORFLAG_AUTO:
 628                 p = getenv("CLICOLOR");
 629                 p2 = getenv("COLORTERM");
 630                 if ((p != NULL && *p != '\0') || (p2 != NULL && *p2 != '\0'))
 631                         return isatty(STDOUT_FILENO);
 632                 break;
 633         case COLORFLAG_ALWAYS:
 634                 return (true);
 635         case COLORFLAG_NEVER:
 636                 return (false);
 637         }
 638
 639         return (false);
 640 }
 641
 642 static char *
 643 splice(char *dir, char *path)
 644 {
 645         char *tail, *buf;
 646         size_t dirlen;
 647
 648         dirlen = strlen(dir);
 649         while (dirlen != 0 && dir[dirlen - 1] == '/')
 650             dirlen--;
 651         if ((tail = strrchr(path, '/')) == NULL)
 652                 tail = path;
 653         else
 654                 tail++;
 655         xasprintf(&buf, "%.*s/%s", (int)dirlen, dir, tail);
 656         return (buf);
 657 }