builtin-grep.c

   1 /*
   2  * Builtin "git grep"
   3  *
   4  * Copyright (c) 2006 Junio C Hamano
   5  */
   6 #include "cache.h"
   7 #include "blob.h"
   8 #include "tree.h"
   9 #include "commit.h"
  10 #include "tag.h"
  11 #include "tree-walk.h"
  12 #include "builtin.h"
  13 #include "grep.h"
  14
  15 #ifndef NO_EXTERNAL_GREP
  16 #ifdef __unix__
  17 #define NO_EXTERNAL_GREP 0
  18 #else
  19 #define NO_EXTERNAL_GREP 1
  20 #endif
  21 #endif
  22
  23 /*
  24  * git grep pathspecs are somewhat different from diff-tree pathspecs;
  25  * pathname wildcards are allowed.
  26  */
  27 static int pathspec_matches(const char **paths, const char *name)
  28 {
  29         int namelen, i;
  30         if (!paths || !*paths)
  31                 return 1;
  32         namelen = strlen(name);
  33         for (i = 0; paths[i]; i++) {
  34                 const char *match = paths[i];
  35                 int matchlen = strlen(match);
  36                 const char *cp, *meta;
  37
  38                 if (!matchlen ||
  39                     ((matchlen <= namelen) &&
  40                      !strncmp(name, match, matchlen) &&
  41                      (match[matchlen-1] == '/' ||
  42                       name[matchlen] == '\0' || name[matchlen] == '/')))
  43                         return 1;
  44                 if (!fnmatch(match, name, 0))
  45                         return 1;
  46                 if (name[namelen-1] != '/')
  47                         continue;
  48
  49                 /* We are being asked if the directory ("name") is worth
  50                  * descending into.
  51                  *
  52                  * Find the longest leading directory name that does
  53                  * not have metacharacter in the pathspec; the name
  54                  * we are looking at must overlap with that directory.
  55                  */
  56                 for (cp = match, meta = NULL; cp - match < matchlen; cp++) {
  57                         char ch = *cp;
  58                         if (ch == '*' || ch == '[' || ch == '?') {
  59                                 meta = cp;
  60                                 break;
  61                         }
  62                 }
  63                 if (!meta)
  64                         meta = cp; /* fully literal */
  65
  66                 if (namelen <= meta - match) {
  67                         /* Looking at "Documentation/" and
  68                          * the pattern says "Documentation/howto/", or
  69                          * "Documentation/diff*.txt".  The name we
  70                          * have should match prefix.
  71                          */
  72                         if (!memcmp(match, name, namelen))
  73                                 return 1;
  74                         continue;
  75                 }
  76
  77                 if (meta - match < namelen) {
  78                         /* Looking at "Documentation/howto/" and
  79                          * the pattern says "Documentation/h*";
  80                          * match up to "Do.../h"; this avoids descending
  81                          * into "Documentation/technical/".
  82                          */
  83                         if (!memcmp(match, name, meta - match))
  84                                 return 1;
  85                         continue;
  86                 }
  87         }
  88         return 0;
  89 }
  90
  91 static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1, const char *name, int tree_name_len)
  92 {
  93         unsigned long size;
  94         char *data;
  95         enum object_type type;
  96         char *to_free = NULL;
  97         int hit;
  98
  99         data = read_sha1_file(sha1, &type, &size);
 100         if (!data) {
 101                 error("'%s': unable to read %s", name, sha1_to_hex(sha1));
 102                 return 0;
 103         }
 104         if (opt->relative && opt->prefix_length) {
 105                 static char name_buf[PATH_MAX];
 106                 char *cp;
 107                 int name_len = strlen(name) - opt->prefix_length + 1;
 108
 109                 if (!tree_name_len)
 110                         name += opt->prefix_length;
 111                 else {
 112                         if (ARRAY_SIZE(name_buf) <= name_len)
 113                                 cp = to_free = xmalloc(name_len);
 114                         else
 115                                 cp = name_buf;
 116                         memcpy(cp, name, tree_name_len);
 117                         strcpy(cp + tree_name_len,
 118                                name + tree_name_len + opt->prefix_length);
 119                         name = cp;
 120                 }
 121         }
 122         hit = grep_buffer(opt, name, data, size);
 123         free(data);
 124         free(to_free);
 125         return hit;
 126 }
 127
 128 static int grep_file(struct grep_opt *opt, const char *filename)
 129 {
 130         struct stat st;
 131         int i;
 132         char *data;
 133         size_t sz;
 134
 135         if (lstat(filename, &st) < 0) {
 136         err_ret:
 137                 if (errno != ENOENT)
 138                         error("'%s': %s", filename, strerror(errno));
 139                 return 0;
 140         }
 141         if (!st.st_size)
 142                 return 0; /* empty file -- no grep hit */
 143         if (!S_ISREG(st.st_mode))
 144                 return 0;
 145         sz = xsize_t(st.st_size);
 146         i = open(filename, O_RDONLY);
 147         if (i < 0)
 148                 goto err_ret;
 149         data = xmalloc(sz + 1);
 150         if (st.st_size != read_in_full(i, data, sz)) {
 151                 error("'%s': short read %s", filename, strerror(errno));
 152                 close(i);
 153                 free(data);
 154                 return 0;
 155         }
 156         close(i);
 157         if (opt->relative && opt->prefix_length)
 158                 filename += opt->prefix_length;
 159         i = grep_buffer(opt, filename, data, sz);
 160         free(data);
 161         return i;
 162 }
 163
 164 #if !NO_EXTERNAL_GREP
 165 static int exec_grep(int argc, const char **argv)
 166 {
 167         pid_t pid;
 168         int status;
 169
 170         argv[argc] = NULL;
 171         pid = fork();
 172         if (pid < 0)
 173                 return pid;
 174         if (!pid) {
 175                 execvp("grep", (char **) argv);
 176                 exit(255);
 177         }
 178         while (waitpid(pid, &status, 0) < 0) {
 179                 if (errno == EINTR)
 180                         continue;
 181                 return -1;
 182         }
 183         if (WIFEXITED(status)) {
 184                 if (!WEXITSTATUS(status))
 185                         return 1;
 186                 return 0;
 187         }
 188         return -1;
 189 }
 190
 191 #define MAXARGS 1000
 192 #define ARGBUF 4096
 193 #define push_arg(a) do { \
 194         if (nr < MAXARGS) argv[nr++] = (a); \
 195         else die("maximum number of args exceeded"); \
 196         } while (0)
 197
 198 /*
 199  * If you send a singleton filename to grep, it does not give
 200  * the name of the file.  GNU grep has "-H" but we would want
 201  * that behaviour in a portable way.
 202  *
 203  * So we keep two pathnames in argv buffer unsent to grep in
 204  * the main loop if we need to do more than one grep.
 205  */
 206 static int flush_grep(struct grep_opt *opt,
 207                       int argc, int arg0, const char **argv, int *kept)
 208 {
 209         int status;
 210         int count = argc - arg0;
 211         const char *kept_0 = NULL;
 212
 213         if (count <= 2) {
 214                 /*
 215                  * Because we keep at least 2 paths in the call from
 216                  * the main loop (i.e. kept != NULL), and MAXARGS is
 217                  * far greater than 2, this usually is a call to
 218                  * conclude the grep.  However, the user could attempt
 219                  * to overflow the argv buffer by giving too many
 220                  * options to leave very small number of real
 221                  * arguments even for the call in the main loop.
 222                  */
 223                 if (kept)
 224                         die("insanely many options to grep");
 225
 226                 /*
 227                  * If we have two or more paths, we do not have to do
 228                  * anything special, but we need to push /dev/null to
 229                  * get "-H" behaviour of GNU grep portably but when we
 230                  * are not doing "-l" nor "-L" nor "-c".
 231                  */
 232                 if (count == 1 &&
 233                     !opt->name_only &&
 234                     !opt->unmatch_name_only &&
 235                     !opt->count) {
 236                         argv[argc++] = "/dev/null";
 237                         argv[argc] = NULL;
 238                 }
 239         }
 240
 241         else if (kept) {
 242                 /*
 243                  * Called because we found many paths and haven't finished
 244                  * iterating over the cache yet.  We keep two paths
 245                  * for the concluding call.  argv[argc-2] and argv[argc-1]
 246                  * has the last two paths, so save the first one away,
 247                  * replace it with NULL while sending the list to grep,
 248                  * and recover them after we are done.
 249                  */
 250                 *kept = 2;
 251                 kept_0 = argv[argc-2];
 252                 argv[argc-2] = NULL;
 253                 argc -= 2;
 254         }
 255
 256         status = exec_grep(argc, argv);
 257
 258         if (kept_0) {
 259                 /*
 260                  * Then recover them.  Now the last arg is beyond the
 261                  * terminating NULL which is at argc, and the second
 262                  * from the last is what we saved away in kept_0
 263                  */
 264                 argv[arg0++] = kept_0;
 265                 argv[arg0] = argv[argc+1];
 266         }
 267         return status;
 268 }
 269
 270 static int external_grep(struct grep_opt *opt, const char **paths, int cached)
 271 {
 272         int i, nr, argc, hit, len, status;
 273         const char *argv[MAXARGS+1];
 274         char randarg[ARGBUF];
 275         char *argptr = randarg;
 276         struct grep_pat *p;
 277
 278         if (opt->extended || (opt->relative && opt->prefix_length))
 279                 return -1;
 280         len = nr = 0;
 281         push_arg("grep");
 282         if (opt->fixed)
 283                 push_arg("-F");
 284         if (opt->linenum)
 285                 push_arg("-n");
 286         if (!opt->pathname)
 287                 push_arg("-h");
 288         if (opt->regflags & REG_EXTENDED)
 289                 push_arg("-E");
 290         if (opt->regflags & REG_ICASE)
 291                 push_arg("-i");
 292         if (opt->word_regexp)
 293                 push_arg("-w");
 294         if (opt->name_only)
 295                 push_arg("-l");
 296         if (opt->unmatch_name_only)
 297                 push_arg("-L");
 298         if (opt->count)
 299                 push_arg("-c");
 300         if (opt->post_context || opt->pre_context) {
 301                 if (opt->post_context != opt->pre_context) {
 302                         if (opt->pre_context) {
 303                                 push_arg("-B");
 304                                 len += snprintf(argptr, sizeof(randarg)-len,
 305                                                 "%u", opt->pre_context) + 1;
 306                                 if (sizeof(randarg) <= len)
 307                                         die("maximum length of args exceeded");
 308                                 push_arg(argptr);
 309                                 argptr += len;
 310                         }
 311                         if (opt->post_context) {
 312                                 push_arg("-A");
 313                                 len += snprintf(argptr, sizeof(randarg)-len,
 314                                                 "%u", opt->post_context) + 1;
 315                                 if (sizeof(randarg) <= len)
 316                                         die("maximum length of args exceeded");
 317                                 push_arg(argptr);
 318                                 argptr += len;
 319                         }
 320                 }
 321                 else {
 322                         push_arg("-C");
 323                         len += snprintf(argptr, sizeof(randarg)-len,
 324                                         "%u", opt->post_context) + 1;
 325                         if (sizeof(randarg) <= len)
 326                                 die("maximum length of args exceeded");
 327                         push_arg(argptr);
 328                         argptr += len;
 329                 }
 330         }
 331         for (p = opt->pattern_list; p; p = p->next) {
 332                 push_arg("-e");
 333                 push_arg(p->pattern);
 334         }
 335
 336         hit = 0;
 337         argc = nr;
 338         for (i = 0; i < active_nr; i++) {
 339                 struct cache_entry *ce = active_cache[i];
 340                 char *name;
 341                 int kept;
 342                 if (!S_ISREG(ce->ce_mode))
 343                         continue;
 344                 if (!pathspec_matches(paths, ce->name))
 345                         continue;
 346                 name = ce->name;
 347                 if (name[0] == '-') {
 348                         int len = ce_namelen(ce);
 349                         name = xmalloc(len + 3);
 350                         memcpy(name, "./", 2);
 351                         memcpy(name + 2, ce->name, len + 1);
 352                 }
 353                 argv[argc++] = name;
 354                 if (MAXARGS <= argc) {
 355                         status = flush_grep(opt, argc, nr, argv, &kept);
 356                         if (0 < status)
 357                                 hit = 1;
 358                         argc = nr + kept;
 359                 }
 360                 if (ce_stage(ce)) {
 361                         do {
 362                                 i++;
 363                         } while (i < active_nr &&
 364                                  !strcmp(ce->name, active_cache[i]->name));
 365                         i--; /* compensate for loop control */
 366                 }
 367         }
 368         if (argc > nr) {
 369                 status = flush_grep(opt, argc, nr, argv, NULL);
 370                 if (0 < status)
 371                         hit = 1;
 372         }
 373         return hit;
 374 }
 375 #endif
 376
 377 static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 378 {
 379         int hit = 0;
 380         int nr;
 381         read_cache();
 382
 383 #if !NO_EXTERNAL_GREP
 384         /*
 385          * Use the external "grep" command for the case where
 386          * we grep through the checked-out files. It tends to
 387          * be a lot more optimized
 388          */
 389         if (!cached) {
 390                 hit = external_grep(opt, paths, cached);
 391                 if (hit >= 0)
 392                         return hit;
 393         }
 394 #endif
 395
 396         for (nr = 0; nr < active_nr; nr++) {
 397                 struct cache_entry *ce = active_cache[nr];
 398                 if (!S_ISREG(ce->ce_mode))
 399                         continue;
 400                 if (!pathspec_matches(paths, ce->name))
 401                         continue;
 402                 if (cached) {
 403                         if (ce_stage(ce))
 404                                 continue;
 405                         hit |= grep_sha1(opt, ce->sha1, ce->name, 0);
 406                 }
 407                 else
 408                         hit |= grep_file(opt, ce->name);
 409                 if (ce_stage(ce)) {
 410                         do {
 411                                 nr++;
 412                         } while (nr < active_nr &&
 413                                  !strcmp(ce->name, active_cache[nr]->name));
 414                         nr--; /* compensate for loop control */
 415                 }
 416         }
 417         free_grep_patterns(opt);
 418         return hit;
 419 }
 420
 421 static int grep_tree(struct grep_opt *opt, const char **paths,
 422                      struct tree_desc *tree,
 423                      const char *tree_name, const char *base)
 424 {
 425         int len;
 426         int hit = 0;
 427         struct name_entry entry;
 428         char *down;
 429         int tn_len = strlen(tree_name);
 430         struct strbuf pathbuf;
 431
 432         strbuf_init(&pathbuf, PATH_MAX + tn_len);
 433
 434         if (tn_len) {
 435                 strbuf_add(&pathbuf, tree_name, tn_len);
 436                 strbuf_addch(&pathbuf, ':');
 437                 tn_len = pathbuf.len;
 438         }
 439         strbuf_addstr(&pathbuf, base);
 440         len = pathbuf.len;
 441
 442         while (tree_entry(tree, &entry)) {
 443                 int te_len = tree_entry_len(entry.path, entry.sha1);
 444                 pathbuf.len = len;
 445                 strbuf_add(&pathbuf, entry.path, te_len);
 446
 447                 if (S_ISDIR(entry.mode))
 448                         /* Match "abc/" against pathspec to
 449                          * decide if we want to descend into "abc"
 450                          * directory.
 451                          */
 452                         strbuf_addch(&pathbuf, '/');
 453
 454                 down = pathbuf.buf + tn_len;
 455                 if (!pathspec_matches(paths, down))
 456                         ;
 457                 else if (S_ISREG(entry.mode))
 458                         hit |= grep_sha1(opt, entry.sha1, pathbuf.buf, tn_len);
 459                 else if (S_ISDIR(entry.mode)) {
 460                         enum object_type type;
 461                         struct tree_desc sub;
 462                         void *data;
 463                         unsigned long size;
 464
 465                         data = read_sha1_file(entry.sha1, &type, &size);
 466                         if (!data)
 467                                 die("unable to read tree (%s)",
 468                                     sha1_to_hex(entry.sha1));
 469                         init_tree_desc(&sub, data, size);
 470                         hit |= grep_tree(opt, paths, &sub, tree_name, down);
 471                         free(data);
 472                 }
 473         }
 474         strbuf_release(&pathbuf);
 475         return hit;
 476 }
 477
 478 static int grep_object(struct grep_opt *opt, const char **paths,
 479                        struct object *obj, const char *name)
 480 {
 481         if (obj->type == OBJ_BLOB)
 482                 return grep_sha1(opt, obj->sha1, name, 0);
 483         if (obj->type == OBJ_COMMIT || obj->type == OBJ_TREE) {
 484                 struct tree_desc tree;
 485                 void *data;
 486                 unsigned long size;
 487                 int hit;
 488                 data = read_object_with_reference(obj->sha1, tree_type,
 489                                                   &size, NULL);
 490                 if (!data)
 491                         die("unable to read tree (%s)", sha1_to_hex(obj->sha1));
 492                 init_tree_desc(&tree, data, size);
 493                 hit = grep_tree(opt, paths, &tree, name, "");
 494                 free(data);
 495                 return hit;
 496         }
 497         die("unable to grep from object of type %s", typename(obj->type));
 498 }
 499
 500 static const char builtin_grep_usage[] =
 501 "git-grep <option>* [-e] <pattern> <rev>* [[--] <path>...]";
 502
 503 static const char emsg_invalid_context_len[] =
 504 "%s: invalid context length argument";
 505 static const char emsg_missing_context_len[] =
 506 "missing context length argument";
 507 static const char emsg_missing_argument[] =
 508 "option requires an argument -%s";
 509
 510 int cmd_grep(int argc, const char **argv, const char *prefix)
 511 {
 512         int hit = 0;
 513         int cached = 0;
 514         int seen_dashdash = 0;
 515         struct grep_opt opt;
 516         struct object_array list = { 0, 0, NULL };
 517         const char **paths = NULL;
 518         int i;
 519
 520         memset(&opt, 0, sizeof(opt));
 521         opt.prefix_length = (prefix && *prefix) ? strlen(prefix) : 0;
 522         opt.relative = 1;
 523         opt.pathname = 1;
 524         opt.pattern_tail = &opt.pattern_list;
 525         opt.regflags = REG_NEWLINE;
 526
 527         /*
 528          * If there is no -- then the paths must exist in the working
 529          * tree.  If there is no explicit pattern specified with -e or
 530          * -f, we take the first unrecognized non option to be the
 531          * pattern, but then what follows it must be zero or more
 532          * valid refs up to the -- (if exists), and then existing
 533          * paths.  If there is an explicit pattern, then the first
 534          * unrecognized non option is the beginning of the refs list
 535          * that continues up to the -- (if exists), and then paths.
 536          */
 537
 538         while (1 < argc) {
 539                 const char *arg = argv[1];
 540                 argc--; argv++;
 541                 if (!strcmp("--cached", arg)) {
 542                         cached = 1;
 543                         continue;
 544                 }
 545                 if (!strcmp("-a", arg) ||
 546                     !strcmp("--text", arg)) {
 547                         opt.binary = GREP_BINARY_TEXT;
 548                         continue;
 549                 }
 550                 if (!strcmp("-i", arg) ||
 551                     !strcmp("--ignore-case", arg)) {
 552                         opt.regflags |= REG_ICASE;
 553                         continue;
 554                 }
 555                 if (!strcmp("-I", arg)) {
 556                         opt.binary = GREP_BINARY_NOMATCH;
 557                         continue;
 558                 }
 559                 if (!strcmp("-v", arg) ||
 560                     !strcmp("--invert-match", arg)) {
 561                         opt.invert = 1;
 562                         continue;
 563                 }
 564                 if (!strcmp("-E", arg) ||
 565                     !strcmp("--extended-regexp", arg)) {
 566                         opt.regflags |= REG_EXTENDED;
 567                         continue;
 568                 }
 569                 if (!strcmp("-F", arg) ||
 570                     !strcmp("--fixed-strings", arg)) {
 571                         opt.fixed = 1;
 572                         continue;
 573                 }
 574                 if (!strcmp("-G", arg) ||
 575                     !strcmp("--basic-regexp", arg)) {
 576                         opt.regflags &= ~REG_EXTENDED;
 577                         continue;
 578                 }
 579                 if (!strcmp("-n", arg)) {
 580                         opt.linenum = 1;
 581                         continue;
 582                 }
 583                 if (!strcmp("-h", arg)) {
 584                         opt.pathname = 0;
 585                         continue;
 586                 }
 587                 if (!strcmp("-H", arg)) {
 588                         opt.pathname = 1;
 589                         continue;
 590                 }
 591                 if (!strcmp("-l", arg) ||
 592                     !strcmp("--name-only", arg) ||
 593                     !strcmp("--files-with-matches", arg)) {
 594                         opt.name_only = 1;
 595                         continue;
 596                 }
 597                 if (!strcmp("-L", arg) ||
 598                     !strcmp("--files-without-match", arg)) {
 599                         opt.unmatch_name_only = 1;
 600                         continue;
 601                 }
 602                 if (!strcmp("-c", arg) ||
 603                     !strcmp("--count", arg)) {
 604                         opt.count = 1;
 605                         continue;
 606                 }
 607                 if (!strcmp("-w", arg) ||
 608                     !strcmp("--word-regexp", arg)) {
 609                         opt.word_regexp = 1;
 610                         continue;
 611                 }
 612                 if (!prefixcmp(arg, "-A") ||
 613                     !prefixcmp(arg, "-B") ||
 614                     !prefixcmp(arg, "-C") ||
 615                     (arg[0] == '-' && '1' <= arg[1] && arg[1] <= '9')) {
 616                         unsigned num;
 617                         const char *scan;
 618                         switch (arg[1]) {
 619                         case 'A': case 'B': case 'C':
 620                                 if (!arg[2]) {
 621                                         if (argc <= 1)
 622                                                 die(emsg_missing_context_len);
 623                                         scan = *++argv;
 624                                         argc--;
 625                                 }
 626                                 else
 627                                         scan = arg + 2;
 628                                 break;
 629                         default:
 630                                 scan = arg + 1;
 631                                 break;
 632                         }
 633                         if (strtoul_ui(scan, 10, &num))
 634                                 die(emsg_invalid_context_len, scan);
 635                         switch (arg[1]) {
 636                         case 'A':
 637                                 opt.post_context = num;
 638                                 break;
 639                         default:
 640                         case 'C':
 641                                 opt.post_context = num;
 642                         case 'B':
 643                                 opt.pre_context = num;
 644                                 break;
 645                         }
 646                         continue;
 647                 }
 648                 if (!strcmp("-f", arg)) {
 649                         FILE *patterns;
 650                         int lno = 0;
 651                         char buf[1024];
 652                         if (argc <= 1)
 653                                 die(emsg_missing_argument, arg);
 654                         patterns = fopen(argv[1], "r");
 655                         if (!patterns)
 656                                 die("'%s': %s", argv[1], strerror(errno));
 657                         while (fgets(buf, sizeof(buf), patterns)) {
 658                                 int len = strlen(buf);
 659                                 if (len && buf[len-1] == '\n')
 660                                         buf[len-1] = 0;
 661                                 /* ignore empty line like grep does */
 662                                 if (!buf[0])
 663                                         continue;
 664                                 append_grep_pattern(&opt, xstrdup(buf),
 665                                                     argv[1], ++lno,
 666                                                     GREP_PATTERN);
 667                         }
 668                         fclose(patterns);
 669                         argv++;
 670                         argc--;
 671                         continue;
 672                 }
 673                 if (!strcmp("--not", arg)) {
 674                         append_grep_pattern(&opt, arg, "command line", 0,
 675                                             GREP_NOT);
 676                         continue;
 677                 }
 678                 if (!strcmp("--and", arg)) {
 679                         append_grep_pattern(&opt, arg, "command line", 0,
 680                                             GREP_AND);
 681                         continue;
 682                 }
 683                 if (!strcmp("--or", arg))
 684                         continue; /* no-op */
 685                 if (!strcmp("(", arg)) {
 686                         append_grep_pattern(&opt, arg, "command line", 0,
 687                                             GREP_OPEN_PAREN);
 688                         continue;
 689                 }
 690                 if (!strcmp(")", arg)) {
 691                         append_grep_pattern(&opt, arg, "command line", 0,
 692                                             GREP_CLOSE_PAREN);
 693                         continue;
 694                 }
 695                 if (!strcmp("--all-match", arg)) {
 696                         opt.all_match = 1;
 697                         continue;
 698                 }
 699                 if (!strcmp("-e", arg)) {
 700                         if (1 < argc) {
 701                                 append_grep_pattern(&opt, argv[1],
 702                                                     "-e option", 0,
 703                                                     GREP_PATTERN);
 704                                 argv++;
 705                                 argc--;
 706                                 continue;
 707                         }
 708                         die(emsg_missing_argument, arg);
 709                 }
 710                 if (!strcmp("--full-name", arg)) {
 711                         opt.relative = 0;
 712                         continue;
 713                 }
 714                 if (!strcmp("--", arg)) {
 715                         /* later processing wants to have this at argv[1] */
 716                         argv--;
 717                         argc++;
 718                         break;
 719                 }
 720                 if (*arg == '-')
 721                         usage(builtin_grep_usage);
 722
 723                 /* First unrecognized non-option token */
 724                 if (!opt.pattern_list) {
 725                         append_grep_pattern(&opt, arg, "command line", 0,
 726                                             GREP_PATTERN);
 727                         break;
 728                 }
 729                 else {
 730                         /* We are looking at the first path or rev;
 731                          * it is found at argv[1] after leaving the
 732                          * loop.
 733                          */
 734                         argc++; argv--;
 735                         break;
 736                 }
 737         }
 738
 739         if (!opt.pattern_list)
 740                 die("no pattern given.");
 741         if ((opt.regflags != REG_NEWLINE) && opt.fixed)
 742                 die("cannot mix --fixed-strings and regexp");
 743         compile_grep_patterns(&opt);
 744
 745         /* Check revs and then paths */
 746         for (i = 1; i < argc; i++) {
 747                 const char *arg = argv[i];
 748                 unsigned char sha1[20];
 749                 /* Is it a rev? */
 750                 if (!get_sha1(arg, sha1)) {
 751                         struct object *object = parse_object(sha1);
 752                         if (!object)
 753                                 die("bad object %s", arg);
 754                         add_object_array(object, arg, &list);
 755                         continue;
 756                 }
 757                 if (!strcmp(arg, "--")) {
 758                         i++;
 759                         seen_dashdash = 1;
 760                 }
 761                 break;
 762         }
 763
 764         /* The rest are paths */
 765         if (!seen_dashdash) {
 766                 int j;
 767                 for (j = i; j < argc; j++)
 768                         verify_filename(prefix, argv[j]);
 769         }
 770
 771         if (i < argc) {
 772                 paths = get_pathspec(prefix, argv + i);
 773                 if (opt.prefix_length && opt.relative) {
 774                         /* Make sure we do not get outside of paths */
 775                         for (i = 0; paths[i]; i++)
 776                                 if (strncmp(prefix, paths[i], opt.prefix_length))
 777                                         die("git-grep: cannot generate relative filenames containing '..'");
 778                 }
 779         }
 780         else if (prefix) {
 781                 paths = xcalloc(2, sizeof(const char *));
 782                 paths[0] = prefix;
 783                 paths[1] = NULL;
 784         }
 785
 786         if (!list.nr)
 787                 return !grep_cache(&opt, paths, cached);
 788
 789         if (cached)
 790                 die("both --cached and trees are given.");
 791
 792         for (i = 0; i < list.nr; i++) {
 793                 struct object *real_obj;
 794                 real_obj = deref_tag(list.objects[i].item, NULL, 0);
 795                 if (grep_object(&opt, paths, real_obj, list.objects[i].name))
 796                         hit = 1;
 797         }
 798         free_grep_patterns(&opt);
 799         return !hit;
 800 }