Merge branch 'maint'
[git] / 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 <regex.h>
14 #include <fnmatch.h>
15 #include <sys/wait.h>
16
17 /*
18  * git grep pathspecs are somewhat different from diff-tree pathspecs;
19  * pathname wildcards are allowed.
20  */
21 static int pathspec_matches(const char **paths, const char *name)
22 {
23         int namelen, i;
24         if (!paths || !*paths)
25                 return 1;
26         namelen = strlen(name);
27         for (i = 0; paths[i]; i++) {
28                 const char *match = paths[i];
29                 int matchlen = strlen(match);
30                 const char *cp, *meta;
31
32                 if (!matchlen ||
33                     ((matchlen <= namelen) &&
34                      !strncmp(name, match, matchlen) &&
35                      (match[matchlen-1] == '/' ||
36                       name[matchlen] == '\0' || name[matchlen] == '/')))
37                         return 1;
38                 if (!fnmatch(match, name, 0))
39                         return 1;
40                 if (name[namelen-1] != '/')
41                         continue;
42
43                 /* We are being asked if the directory ("name") is worth
44                  * descending into.
45                  *
46                  * Find the longest leading directory name that does
47                  * not have metacharacter in the pathspec; the name
48                  * we are looking at must overlap with that directory.
49                  */
50                 for (cp = match, meta = NULL; cp - match < matchlen; cp++) {
51                         char ch = *cp;
52                         if (ch == '*' || ch == '[' || ch == '?') {
53                                 meta = cp;
54                                 break;
55                         }
56                 }
57                 if (!meta)
58                         meta = cp; /* fully literal */
59
60                 if (namelen <= meta - match) {
61                         /* Looking at "Documentation/" and
62                          * the pattern says "Documentation/howto/", or
63                          * "Documentation/diff*.txt".  The name we
64                          * have should match prefix.
65                          */
66                         if (!memcmp(match, name, namelen))
67                                 return 1;
68                         continue;
69                 }
70
71                 if (meta - match < namelen) {
72                         /* Looking at "Documentation/howto/" and
73                          * the pattern says "Documentation/h*";
74                          * match up to "Do.../h"; this avoids descending
75                          * into "Documentation/technical/".
76                          */
77                         if (!memcmp(match, name, meta - match))
78                                 return 1;
79                         continue;
80                 }
81         }
82         return 0;
83 }
84
85 enum grep_pat_token {
86         GREP_PATTERN,
87         GREP_AND,
88         GREP_OPEN_PAREN,
89         GREP_CLOSE_PAREN,
90         GREP_NOT,
91         GREP_OR,
92 };
93
94 struct grep_pat {
95         struct grep_pat *next;
96         const char *origin;
97         int no;
98         enum grep_pat_token token;
99         const char *pattern;
100         regex_t regexp;
101 };
102
103 enum grep_expr_node {
104         GREP_NODE_ATOM,
105         GREP_NODE_NOT,
106         GREP_NODE_AND,
107         GREP_NODE_OR,
108 };
109
110 struct grep_expr {
111         enum grep_expr_node node;
112         union {
113                 struct grep_pat *atom;
114                 struct grep_expr *unary;
115                 struct {
116                         struct grep_expr *left;
117                         struct grep_expr *right;
118                 } binary;
119         } u;
120 };
121
122 struct grep_opt {
123         struct grep_pat *pattern_list;
124         struct grep_pat **pattern_tail;
125         struct grep_expr *pattern_expression;
126         int prefix_length;
127         regex_t regexp;
128         unsigned linenum:1;
129         unsigned invert:1;
130         unsigned name_only:1;
131         unsigned unmatch_name_only:1;
132         unsigned count:1;
133         unsigned word_regexp:1;
134         unsigned fixed:1;
135 #define GREP_BINARY_DEFAULT     0
136 #define GREP_BINARY_NOMATCH     1
137 #define GREP_BINARY_TEXT        2
138         unsigned binary:2;
139         unsigned extended:1;
140         unsigned relative:1;
141         int regflags;
142         unsigned pre_context;
143         unsigned post_context;
144 };
145
146 static void add_pattern(struct grep_opt *opt, const char *pat,
147                         const char *origin, int no, enum grep_pat_token t)
148 {
149         struct grep_pat *p = xcalloc(1, sizeof(*p));
150         p->pattern = pat;
151         p->origin = origin;
152         p->no = no;
153         p->token = t;
154         *opt->pattern_tail = p;
155         opt->pattern_tail = &p->next;
156         p->next = NULL;
157 }
158
159 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
160 {
161         int err = regcomp(&p->regexp, p->pattern, opt->regflags);
162         if (err) {
163                 char errbuf[1024];
164                 char where[1024];
165                 if (p->no)
166                         sprintf(where, "In '%s' at %d, ",
167                                 p->origin, p->no);
168                 else if (p->origin)
169                         sprintf(where, "%s, ", p->origin);
170                 else
171                         where[0] = 0;
172                 regerror(err, &p->regexp, errbuf, 1024);
173                 regfree(&p->regexp);
174                 die("%s'%s': %s", where, p->pattern, errbuf);
175         }
176 }
177
178 #if DEBUG
179 static inline void indent(int in)
180 {
181         int i;
182         for (i = 0; i < in; i++) putchar(' ');
183 }
184
185 static void dump_pattern_exp(struct grep_expr *x, int in)
186 {
187         switch (x->node) {
188         case GREP_NODE_ATOM:
189                 indent(in);
190                 puts(x->u.atom->pattern);
191                 break;
192         case GREP_NODE_NOT:
193                 indent(in);
194                 puts("--not");
195                 dump_pattern_exp(x->u.unary, in+1);
196                 break;
197         case GREP_NODE_AND:
198                 dump_pattern_exp(x->u.binary.left, in+1);
199                 indent(in);
200                 puts("--and");
201                 dump_pattern_exp(x->u.binary.right, in+1);
202                 break;
203         case GREP_NODE_OR:
204                 dump_pattern_exp(x->u.binary.left, in+1);
205                 indent(in);
206                 puts("--or");
207                 dump_pattern_exp(x->u.binary.right, in+1);
208                 break;
209         }
210 }
211
212 static void looking_at(const char *msg, struct grep_pat **list)
213 {
214         struct grep_pat *p = *list;
215         fprintf(stderr, "%s: looking at ", msg);
216         if (!p)
217                 fprintf(stderr, "empty\n");
218         else
219                 fprintf(stderr, "<%s>\n", p->pattern);
220 }
221 #else
222 #define looking_at(a,b) do {} while(0)
223 #endif
224
225 static struct grep_expr *compile_pattern_expr(struct grep_pat **);
226 static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
227 {
228         struct grep_pat *p;
229         struct grep_expr *x;
230
231         looking_at("atom", list);
232
233         p = *list;
234         switch (p->token) {
235         case GREP_PATTERN: /* atom */
236                 x = xcalloc(1, sizeof (struct grep_expr));
237                 x->node = GREP_NODE_ATOM;
238                 x->u.atom = p;
239                 *list = p->next;
240                 return x;
241         case GREP_OPEN_PAREN:
242                 *list = p->next;
243                 x = compile_pattern_expr(list);
244                 if (!x)
245                         return NULL;
246                 if (!*list || (*list)->token != GREP_CLOSE_PAREN)
247                         die("unmatched parenthesis");
248                 *list = (*list)->next;
249                 return x;
250         default:
251                 return NULL;
252         }
253 }
254
255 static struct grep_expr *compile_pattern_not(struct grep_pat **list)
256 {
257         struct grep_pat *p;
258         struct grep_expr *x;
259
260         looking_at("not", list);
261
262         p = *list;
263         switch (p->token) {
264         case GREP_NOT:
265                 if (!p->next)
266                         die("--not not followed by pattern expression");
267                 *list = p->next;
268                 x = xcalloc(1, sizeof (struct grep_expr));
269                 x->node = GREP_NODE_NOT;
270                 x->u.unary = compile_pattern_not(list);
271                 if (!x->u.unary)
272                         die("--not followed by non pattern expression");
273                 return x;
274         default:
275                 return compile_pattern_atom(list);
276         }
277 }
278
279 static struct grep_expr *compile_pattern_and(struct grep_pat **list)
280 {
281         struct grep_pat *p;
282         struct grep_expr *x, *y, *z;
283
284         looking_at("and", list);
285
286         x = compile_pattern_not(list);
287         p = *list;
288         if (p && p->token == GREP_AND) {
289                 if (!p->next)
290                         die("--and not followed by pattern expression");
291                 *list = p->next;
292                 y = compile_pattern_and(list);
293                 if (!y)
294                         die("--and not followed by pattern expression");
295                 z = xcalloc(1, sizeof (struct grep_expr));
296                 z->node = GREP_NODE_AND;
297                 z->u.binary.left = x;
298                 z->u.binary.right = y;
299                 return z;
300         }
301         return x;
302 }
303
304 static struct grep_expr *compile_pattern_or(struct grep_pat **list)
305 {
306         struct grep_pat *p;
307         struct grep_expr *x, *y, *z;
308
309         looking_at("or", list);
310
311         x = compile_pattern_and(list);
312         p = *list;
313         if (x && p && p->token != GREP_CLOSE_PAREN) {
314                 y = compile_pattern_or(list);
315                 if (!y)
316                         die("not a pattern expression %s", p->pattern);
317                 z = xcalloc(1, sizeof (struct grep_expr));
318                 z->node = GREP_NODE_OR;
319                 z->u.binary.left = x;
320                 z->u.binary.right = y;
321                 return z;
322         }
323         return x;
324 }
325
326 static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
327 {
328         looking_at("expr", list);
329
330         return compile_pattern_or(list);
331 }
332
333 static void compile_patterns(struct grep_opt *opt)
334 {
335         struct grep_pat *p;
336
337         /* First compile regexps */
338         for (p = opt->pattern_list; p; p = p->next) {
339                 if (p->token == GREP_PATTERN)
340                         compile_regexp(p, opt);
341                 else
342                         opt->extended = 1;
343         }
344
345         if (!opt->extended)
346                 return;
347
348         /* Then bundle them up in an expression.
349          * A classic recursive descent parser would do.
350          */
351         p = opt->pattern_list;
352         opt->pattern_expression = compile_pattern_expr(&p);
353 #if DEBUG
354         dump_pattern_exp(opt->pattern_expression, 0);
355 #endif
356         if (p)
357                 die("incomplete pattern expression: %s", p->pattern);
358 }
359
360 static char *end_of_line(char *cp, unsigned long *left)
361 {
362         unsigned long l = *left;
363         while (l && *cp != '\n') {
364                 l--;
365                 cp++;
366         }
367         *left = l;
368         return cp;
369 }
370
371 static int word_char(char ch)
372 {
373         return isalnum(ch) || ch == '_';
374 }
375
376 static void show_line(struct grep_opt *opt, const char *bol, const char *eol,
377                       const char *name, unsigned lno, char sign)
378 {
379         printf("%s%c", name, sign);
380         if (opt->linenum)
381                 printf("%d%c", lno, sign);
382         printf("%.*s\n", (int)(eol-bol), bol);
383 }
384
385 /*
386  * NEEDSWORK: share code with diff.c
387  */
388 #define FIRST_FEW_BYTES 8000
389 static int buffer_is_binary(const char *ptr, unsigned long size)
390 {
391         if (FIRST_FEW_BYTES < size)
392                 size = FIRST_FEW_BYTES;
393         if (memchr(ptr, 0, size))
394                 return 1;
395         return 0;
396 }
397
398 static int fixmatch(const char *pattern, char *line, regmatch_t *match)
399 {
400         char *hit = strstr(line, pattern);
401         if (!hit) {
402                 match->rm_so = match->rm_eo = -1;
403                 return REG_NOMATCH;
404         }
405         else {
406                 match->rm_so = hit - line;
407                 match->rm_eo = match->rm_so + strlen(pattern);
408                 return 0;
409         }
410 }
411
412 static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol, char *eol)
413 {
414         int hit = 0;
415         int at_true_bol = 1;
416         regmatch_t pmatch[10];
417
418  again:
419         if (!opt->fixed) {
420                 regex_t *exp = &p->regexp;
421                 hit = !regexec(exp, bol, ARRAY_SIZE(pmatch),
422                                pmatch, 0);
423         }
424         else {
425                 hit = !fixmatch(p->pattern, bol, pmatch);
426         }
427
428         if (hit && opt->word_regexp) {
429                 if ((pmatch[0].rm_so < 0) ||
430                     (eol - bol) <= pmatch[0].rm_so ||
431                     (pmatch[0].rm_eo < 0) ||
432                     (eol - bol) < pmatch[0].rm_eo)
433                         die("regexp returned nonsense");
434
435                 /* Match beginning must be either beginning of the
436                  * line, or at word boundary (i.e. the last char must
437                  * not be a word char).  Similarly, match end must be
438                  * either end of the line, or at word boundary
439                  * (i.e. the next char must not be a word char).
440                  */
441                 if ( ((pmatch[0].rm_so == 0 && at_true_bol) ||
442                       !word_char(bol[pmatch[0].rm_so-1])) &&
443                      ((pmatch[0].rm_eo == (eol-bol)) ||
444                       !word_char(bol[pmatch[0].rm_eo])) )
445                         ;
446                 else
447                         hit = 0;
448
449                 if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
450                         /* There could be more than one match on the
451                          * line, and the first match might not be
452                          * strict word match.  But later ones could be!
453                          */
454                         bol = pmatch[0].rm_so + bol + 1;
455                         at_true_bol = 0;
456                         goto again;
457                 }
458         }
459         return hit;
460 }
461
462 static int match_expr_eval(struct grep_opt *opt,
463                            struct grep_expr *x,
464                            char *bol, char *eol)
465 {
466         switch (x->node) {
467         case GREP_NODE_ATOM:
468                 return match_one_pattern(opt, x->u.atom, bol, eol);
469                 break;
470         case GREP_NODE_NOT:
471                 return !match_expr_eval(opt, x->u.unary, bol, eol);
472         case GREP_NODE_AND:
473                 return (match_expr_eval(opt, x->u.binary.left, bol, eol) &&
474                         match_expr_eval(opt, x->u.binary.right, bol, eol));
475         case GREP_NODE_OR:
476                 return (match_expr_eval(opt, x->u.binary.left, bol, eol) ||
477                         match_expr_eval(opt, x->u.binary.right, bol, eol));
478         }
479         die("Unexpected node type (internal error) %d\n", x->node);
480 }
481
482 static int match_expr(struct grep_opt *opt, char *bol, char *eol)
483 {
484         struct grep_expr *x = opt->pattern_expression;
485         return match_expr_eval(opt, x, bol, eol);
486 }
487
488 static int match_line(struct grep_opt *opt, char *bol, char *eol)
489 {
490         struct grep_pat *p;
491         if (opt->extended)
492                 return match_expr(opt, bol, eol);
493         for (p = opt->pattern_list; p; p = p->next) {
494                 if (match_one_pattern(opt, p, bol, eol))
495                         return 1;
496         }
497         return 0;
498 }
499
500 static int grep_buffer(struct grep_opt *opt, const char *name,
501                        char *buf, unsigned long size)
502 {
503         char *bol = buf;
504         unsigned long left = size;
505         unsigned lno = 1;
506         struct pre_context_line {
507                 char *bol;
508                 char *eol;
509         } *prev = NULL, *pcl;
510         unsigned last_hit = 0;
511         unsigned last_shown = 0;
512         int binary_match_only = 0;
513         const char *hunk_mark = "";
514         unsigned count = 0;
515
516         if (buffer_is_binary(buf, size)) {
517                 switch (opt->binary) {
518                 case GREP_BINARY_DEFAULT:
519                         binary_match_only = 1;
520                         break;
521                 case GREP_BINARY_NOMATCH:
522                         return 0; /* Assume unmatch */
523                         break;
524                 default:
525                         break;
526                 }
527         }
528
529         if (opt->pre_context)
530                 prev = xcalloc(opt->pre_context, sizeof(*prev));
531         if (opt->pre_context || opt->post_context)
532                 hunk_mark = "--\n";
533
534         while (left) {
535                 char *eol, ch;
536                 int hit = 0;
537
538                 eol = end_of_line(bol, &left);
539                 ch = *eol;
540                 *eol = 0;
541
542                 hit = match_line(opt, bol, eol);
543
544                 /* "grep -v -e foo -e bla" should list lines
545                  * that do not have either, so inversion should
546                  * be done outside.
547                  */
548                 if (opt->invert)
549                         hit = !hit;
550                 if (opt->unmatch_name_only) {
551                         if (hit)
552                                 return 0;
553                         goto next_line;
554                 }
555                 if (hit) {
556                         count++;
557                         if (binary_match_only) {
558                                 printf("Binary file %s matches\n", name);
559                                 return 1;
560                         }
561                         if (opt->name_only) {
562                                 printf("%s\n", name);
563                                 return 1;
564                         }
565                         /* Hit at this line.  If we haven't shown the
566                          * pre-context lines, we would need to show them.
567                          * When asked to do "count", this still show
568                          * the context which is nonsense, but the user
569                          * deserves to get that ;-).
570                          */
571                         if (opt->pre_context) {
572                                 unsigned from;
573                                 if (opt->pre_context < lno)
574                                         from = lno - opt->pre_context;
575                                 else
576                                         from = 1;
577                                 if (from <= last_shown)
578                                         from = last_shown + 1;
579                                 if (last_shown && from != last_shown + 1)
580                                         printf(hunk_mark);
581                                 while (from < lno) {
582                                         pcl = &prev[lno-from-1];
583                                         show_line(opt, pcl->bol, pcl->eol,
584                                                   name, from, '-');
585                                         from++;
586                                 }
587                                 last_shown = lno-1;
588                         }
589                         if (last_shown && lno != last_shown + 1)
590                                 printf(hunk_mark);
591                         if (!opt->count)
592                                 show_line(opt, bol, eol, name, lno, ':');
593                         last_shown = last_hit = lno;
594                 }
595                 else if (last_hit &&
596                          lno <= last_hit + opt->post_context) {
597                         /* If the last hit is within the post context,
598                          * we need to show this line.
599                          */
600                         if (last_shown && lno != last_shown + 1)
601                                 printf(hunk_mark);
602                         show_line(opt, bol, eol, name, lno, '-');
603                         last_shown = lno;
604                 }
605                 if (opt->pre_context) {
606                         memmove(prev+1, prev,
607                                 (opt->pre_context-1) * sizeof(*prev));
608                         prev->bol = bol;
609                         prev->eol = eol;
610                 }
611
612         next_line:
613                 *eol = ch;
614                 bol = eol + 1;
615                 if (!left)
616                         break;
617                 left--;
618                 lno++;
619         }
620
621         if (opt->unmatch_name_only) {
622                 /* We did not see any hit, so we want to show this */
623                 printf("%s\n", name);
624                 return 1;
625         }
626
627         /* NEEDSWORK:
628          * The real "grep -c foo *.c" gives many "bar.c:0" lines,
629          * which feels mostly useless but sometimes useful.  Maybe
630          * make it another option?  For now suppress them.
631          */
632         if (opt->count && count)
633                 printf("%s:%u\n", name, count);
634         return !!last_hit;
635 }
636
637 static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1, const char *name, int tree_name_len)
638 {
639         unsigned long size;
640         char *data;
641         char type[20];
642         char *to_free = NULL;
643         int hit;
644
645         data = read_sha1_file(sha1, type, &size);
646         if (!data) {
647                 error("'%s': unable to read %s", name, sha1_to_hex(sha1));
648                 return 0;
649         }
650         if (opt->relative && opt->prefix_length) {
651                 static char name_buf[PATH_MAX];
652                 char *cp;
653                 int name_len = strlen(name) - opt->prefix_length + 1;
654
655                 if (!tree_name_len)
656                         name += opt->prefix_length;
657                 else {
658                         if (ARRAY_SIZE(name_buf) <= name_len)
659                                 cp = to_free = xmalloc(name_len);
660                         else
661                                 cp = name_buf;
662                         memcpy(cp, name, tree_name_len);
663                         strcpy(cp + tree_name_len,
664                                name + tree_name_len + opt->prefix_length);
665                         name = cp;
666                 }
667         }
668         hit = grep_buffer(opt, name, data, size);
669         free(data);
670         free(to_free);
671         return hit;
672 }
673
674 static int grep_file(struct grep_opt *opt, const char *filename)
675 {
676         struct stat st;
677         int i;
678         char *data;
679         if (lstat(filename, &st) < 0) {
680         err_ret:
681                 if (errno != ENOENT)
682                         error("'%s': %s", filename, strerror(errno));
683                 return 0;
684         }
685         if (!st.st_size)
686                 return 0; /* empty file -- no grep hit */
687         if (!S_ISREG(st.st_mode))
688                 return 0;
689         i = open(filename, O_RDONLY);
690         if (i < 0)
691                 goto err_ret;
692         data = xmalloc(st.st_size + 1);
693         if (st.st_size != xread(i, data, st.st_size)) {
694                 error("'%s': short read %s", filename, strerror(errno));
695                 close(i);
696                 free(data);
697                 return 0;
698         }
699         close(i);
700         if (opt->relative && opt->prefix_length)
701                 filename += opt->prefix_length;
702         i = grep_buffer(opt, filename, data, st.st_size);
703         free(data);
704         return i;
705 }
706
707 static int exec_grep(int argc, const char **argv)
708 {
709         pid_t pid;
710         int status;
711
712         argv[argc] = NULL;
713         pid = fork();
714         if (pid < 0)
715                 return pid;
716         if (!pid) {
717                 execvp("grep", (char **) argv);
718                 exit(255);
719         }
720         while (waitpid(pid, &status, 0) < 0) {
721                 if (errno == EINTR)
722                         continue;
723                 return -1;
724         }
725         if (WIFEXITED(status)) {
726                 if (!WEXITSTATUS(status))
727                         return 1;
728                 return 0;
729         }
730         return -1;
731 }
732
733 #define MAXARGS 1000
734 #define ARGBUF 4096
735 #define push_arg(a) do { \
736         if (nr < MAXARGS) argv[nr++] = (a); \
737         else die("maximum number of args exceeded"); \
738         } while (0)
739
740 static int external_grep(struct grep_opt *opt, const char **paths, int cached)
741 {
742         int i, nr, argc, hit, len, status;
743         const char *argv[MAXARGS+1];
744         char randarg[ARGBUF];
745         char *argptr = randarg;
746         struct grep_pat *p;
747
748         if (opt->extended || (opt->relative && opt->prefix_length))
749                 return -1;
750         len = nr = 0;
751         push_arg("grep");
752         if (opt->fixed)
753                 push_arg("-F");
754         if (opt->linenum)
755                 push_arg("-n");
756         if (opt->regflags & REG_EXTENDED)
757                 push_arg("-E");
758         if (opt->regflags & REG_ICASE)
759                 push_arg("-i");
760         if (opt->word_regexp)
761                 push_arg("-w");
762         if (opt->name_only)
763                 push_arg("-l");
764         if (opt->unmatch_name_only)
765                 push_arg("-L");
766         if (opt->count)
767                 push_arg("-c");
768         if (opt->post_context || opt->pre_context) {
769                 if (opt->post_context != opt->pre_context) {
770                         if (opt->pre_context) {
771                                 push_arg("-B");
772                                 len += snprintf(argptr, sizeof(randarg)-len,
773                                                 "%u", opt->pre_context);
774                                 if (sizeof(randarg) <= len)
775                                         die("maximum length of args exceeded");
776                                 push_arg(argptr);
777                                 argptr += len;
778                         }
779                         if (opt->post_context) {
780                                 push_arg("-A");
781                                 len += snprintf(argptr, sizeof(randarg)-len,
782                                                 "%u", opt->post_context);
783                                 if (sizeof(randarg) <= len)
784                                         die("maximum length of args exceeded");
785                                 push_arg(argptr);
786                                 argptr += len;
787                         }
788                 }
789                 else {
790                         push_arg("-C");
791                         len += snprintf(argptr, sizeof(randarg)-len,
792                                         "%u", opt->post_context);
793                         if (sizeof(randarg) <= len)
794                                 die("maximum length of args exceeded");
795                         push_arg(argptr);
796                         argptr += len;
797                 }
798         }
799         for (p = opt->pattern_list; p; p = p->next) {
800                 push_arg("-e");
801                 push_arg(p->pattern);
802         }
803
804         /*
805          * To make sure we get the header printed out when we want it,
806          * add /dev/null to the paths to grep.  This is unnecessary
807          * (and wrong) with "-l" or "-L", which always print out the
808          * name anyway.
809          *
810          * GNU grep has "-H", but this is portable.
811          */
812         if (!opt->name_only && !opt->unmatch_name_only)
813                 push_arg("/dev/null");
814
815         hit = 0;
816         argc = nr;
817         for (i = 0; i < active_nr; i++) {
818                 struct cache_entry *ce = active_cache[i];
819                 char *name;
820                 if (ce_stage(ce) || !S_ISREG(ntohl(ce->ce_mode)))
821                         continue;
822                 if (!pathspec_matches(paths, ce->name))
823                         continue;
824                 name = ce->name;
825                 if (name[0] == '-') {
826                         int len = ce_namelen(ce);
827                         name = xmalloc(len + 3);
828                         memcpy(name, "./", 2);
829                         memcpy(name + 2, ce->name, len + 1);
830                 }
831                 argv[argc++] = name;
832                 if (argc < MAXARGS)
833                         continue;
834                 status = exec_grep(argc, argv);
835                 if (0 < status)
836                         hit = 1;
837                 argc = nr;
838         }
839         if (argc > nr) {
840                 status = exec_grep(argc, argv);
841                 if (0 < status)
842                         hit = 1;
843         }
844         return hit;
845 }
846
847 static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
848 {
849         int hit = 0;
850         int nr;
851         read_cache();
852
853 #ifdef __unix__
854         /*
855          * Use the external "grep" command for the case where
856          * we grep through the checked-out files. It tends to
857          * be a lot more optimized
858          */
859         if (!cached) {
860                 hit = external_grep(opt, paths, cached);
861                 if (hit >= 0)
862                         return hit;
863         }
864 #endif
865
866         for (nr = 0; nr < active_nr; nr++) {
867                 struct cache_entry *ce = active_cache[nr];
868                 if (ce_stage(ce) || !S_ISREG(ntohl(ce->ce_mode)))
869                         continue;
870                 if (!pathspec_matches(paths, ce->name))
871                         continue;
872                 if (cached)
873                         hit |= grep_sha1(opt, ce->sha1, ce->name, 0);
874                 else
875                         hit |= grep_file(opt, ce->name);
876         }
877         return hit;
878 }
879
880 static int grep_tree(struct grep_opt *opt, const char **paths,
881                      struct tree_desc *tree,
882                      const char *tree_name, const char *base)
883 {
884         int len;
885         int hit = 0;
886         struct name_entry entry;
887         char *down;
888         int tn_len = strlen(tree_name);
889         char *path_buf = xmalloc(PATH_MAX + tn_len + 100);
890
891         if (tn_len) {
892                 tn_len = sprintf(path_buf, "%s:", tree_name);
893                 down = path_buf + tn_len;
894                 strcat(down, base);
895         }
896         else {
897                 down = path_buf;
898                 strcpy(down, base);
899         }
900         len = strlen(path_buf);
901
902         while (tree_entry(tree, &entry)) {
903                 strcpy(path_buf + len, entry.path);
904
905                 if (S_ISDIR(entry.mode))
906                         /* Match "abc/" against pathspec to
907                          * decide if we want to descend into "abc"
908                          * directory.
909                          */
910                         strcpy(path_buf + len + entry.pathlen, "/");
911
912                 if (!pathspec_matches(paths, down))
913                         ;
914                 else if (S_ISREG(entry.mode))
915                         hit |= grep_sha1(opt, entry.sha1, path_buf, tn_len);
916                 else if (S_ISDIR(entry.mode)) {
917                         char type[20];
918                         struct tree_desc sub;
919                         void *data;
920                         data = read_sha1_file(entry.sha1, type, &sub.size);
921                         if (!data)
922                                 die("unable to read tree (%s)",
923                                     sha1_to_hex(entry.sha1));
924                         sub.buf = data;
925                         hit |= grep_tree(opt, paths, &sub, tree_name, down);
926                         free(data);
927                 }
928         }
929         return hit;
930 }
931
932 static int grep_object(struct grep_opt *opt, const char **paths,
933                        struct object *obj, const char *name)
934 {
935         if (obj->type == OBJ_BLOB)
936                 return grep_sha1(opt, obj->sha1, name, 0);
937         if (obj->type == OBJ_COMMIT || obj->type == OBJ_TREE) {
938                 struct tree_desc tree;
939                 void *data;
940                 int hit;
941                 data = read_object_with_reference(obj->sha1, tree_type,
942                                                   &tree.size, NULL);
943                 if (!data)
944                         die("unable to read tree (%s)", sha1_to_hex(obj->sha1));
945                 tree.buf = data;
946                 hit = grep_tree(opt, paths, &tree, name, "");
947                 free(data);
948                 return hit;
949         }
950         die("unable to grep from object of type %s", typename(obj->type));
951 }
952
953 static const char builtin_grep_usage[] =
954 "git-grep <option>* <rev>* [-e] <pattern> [<path>...]";
955
956 static const char emsg_invalid_context_len[] =
957 "%s: invalid context length argument";
958 static const char emsg_missing_context_len[] =
959 "missing context length argument";
960 static const char emsg_missing_argument[] =
961 "option requires an argument -%s";
962
963 int cmd_grep(int argc, const char **argv, const char *prefix)
964 {
965         int hit = 0;
966         int cached = 0;
967         int seen_dashdash = 0;
968         struct grep_opt opt;
969         struct object_array list = { 0, 0, NULL };
970         const char **paths = NULL;
971         int i;
972
973         memset(&opt, 0, sizeof(opt));
974         opt.prefix_length = (prefix && *prefix) ? strlen(prefix) : 0;
975         opt.relative = 1;
976         opt.pattern_tail = &opt.pattern_list;
977         opt.regflags = REG_NEWLINE;
978
979         /*
980          * If there is no -- then the paths must exist in the working
981          * tree.  If there is no explicit pattern specified with -e or
982          * -f, we take the first unrecognized non option to be the
983          * pattern, but then what follows it must be zero or more
984          * valid refs up to the -- (if exists), and then existing
985          * paths.  If there is an explicit pattern, then the first
986          * unrecognized non option is the beginning of the refs list
987          * that continues up to the -- (if exists), and then paths.
988          */
989
990         while (1 < argc) {
991                 const char *arg = argv[1];
992                 argc--; argv++;
993                 if (!strcmp("--cached", arg)) {
994                         cached = 1;
995                         continue;
996                 }
997                 if (!strcmp("-a", arg) ||
998                     !strcmp("--text", arg)) {
999                         opt.binary = GREP_BINARY_TEXT;
1000                         continue;
1001                 }
1002                 if (!strcmp("-i", arg) ||
1003                     !strcmp("--ignore-case", arg)) {
1004                         opt.regflags |= REG_ICASE;
1005                         continue;
1006                 }
1007                 if (!strcmp("-I", arg)) {
1008                         opt.binary = GREP_BINARY_NOMATCH;
1009                         continue;
1010                 }
1011                 if (!strcmp("-v", arg) ||
1012                     !strcmp("--invert-match", arg)) {
1013                         opt.invert = 1;
1014                         continue;
1015                 }
1016                 if (!strcmp("-E", arg) ||
1017                     !strcmp("--extended-regexp", arg)) {
1018                         opt.regflags |= REG_EXTENDED;
1019                         continue;
1020                 }
1021                 if (!strcmp("-F", arg) ||
1022                     !strcmp("--fixed-strings", arg)) {
1023                         opt.fixed = 1;
1024                         continue;
1025                 }
1026                 if (!strcmp("-G", arg) ||
1027                     !strcmp("--basic-regexp", arg)) {
1028                         opt.regflags &= ~REG_EXTENDED;
1029                         continue;
1030                 }
1031                 if (!strcmp("-n", arg)) {
1032                         opt.linenum = 1;
1033                         continue;
1034                 }
1035                 if (!strcmp("-H", arg)) {
1036                         /* We always show the pathname, so this
1037                          * is a noop.
1038                          */
1039                         continue;
1040                 }
1041                 if (!strcmp("-l", arg) ||
1042                     !strcmp("--files-with-matches", arg)) {
1043                         opt.name_only = 1;
1044                         continue;
1045                 }
1046                 if (!strcmp("-L", arg) ||
1047                     !strcmp("--files-without-match", arg)) {
1048                         opt.unmatch_name_only = 1;
1049                         continue;
1050                 }
1051                 if (!strcmp("-c", arg) ||
1052                     !strcmp("--count", arg)) {
1053                         opt.count = 1;
1054                         continue;
1055                 }
1056                 if (!strcmp("-w", arg) ||
1057                     !strcmp("--word-regexp", arg)) {
1058                         opt.word_regexp = 1;
1059                         continue;
1060                 }
1061                 if (!strncmp("-A", arg, 2) ||
1062                     !strncmp("-B", arg, 2) ||
1063                     !strncmp("-C", arg, 2) ||
1064                     (arg[0] == '-' && '1' <= arg[1] && arg[1] <= '9')) {
1065                         unsigned num;
1066                         const char *scan;
1067                         switch (arg[1]) {
1068                         case 'A': case 'B': case 'C':
1069                                 if (!arg[2]) {
1070                                         if (argc <= 1)
1071                                                 die(emsg_missing_context_len);
1072                                         scan = *++argv;
1073                                         argc--;
1074                                 }
1075                                 else
1076                                         scan = arg + 2;
1077                                 break;
1078                         default:
1079                                 scan = arg + 1;
1080                                 break;
1081                         }
1082                         if (sscanf(scan, "%u", &num) != 1)
1083                                 die(emsg_invalid_context_len, scan);
1084                         switch (arg[1]) {
1085                         case 'A':
1086                                 opt.post_context = num;
1087                                 break;
1088                         default:
1089                         case 'C':
1090                                 opt.post_context = num;
1091                         case 'B':
1092                                 opt.pre_context = num;
1093                                 break;
1094                         }
1095                         continue;
1096                 }
1097                 if (!strcmp("-f", arg)) {
1098                         FILE *patterns;
1099                         int lno = 0;
1100                         char buf[1024];
1101                         if (argc <= 1)
1102                                 die(emsg_missing_argument, arg);
1103                         patterns = fopen(argv[1], "r");
1104                         if (!patterns)
1105                                 die("'%s': %s", argv[1], strerror(errno));
1106                         while (fgets(buf, sizeof(buf), patterns)) {
1107                                 int len = strlen(buf);
1108                                 if (buf[len-1] == '\n')
1109                                         buf[len-1] = 0;
1110                                 /* ignore empty line like grep does */
1111                                 if (!buf[0])
1112                                         continue;
1113                                 add_pattern(&opt, strdup(buf), argv[1], ++lno,
1114                                             GREP_PATTERN);
1115                         }
1116                         fclose(patterns);
1117                         argv++;
1118                         argc--;
1119                         continue;
1120                 }
1121                 if (!strcmp("--not", arg)) {
1122                         add_pattern(&opt, arg, "command line", 0, GREP_NOT);
1123                         continue;
1124                 }
1125                 if (!strcmp("--and", arg)) {
1126                         add_pattern(&opt, arg, "command line", 0, GREP_AND);
1127                         continue;
1128                 }
1129                 if (!strcmp("--or", arg))
1130                         continue; /* no-op */
1131                 if (!strcmp("(", arg)) {
1132                         add_pattern(&opt, arg, "command line", 0, GREP_OPEN_PAREN);
1133                         continue;
1134                 }
1135                 if (!strcmp(")", arg)) {
1136                         add_pattern(&opt, arg, "command line", 0, GREP_CLOSE_PAREN);
1137                         continue;
1138                 }
1139                 if (!strcmp("-e", arg)) {
1140                         if (1 < argc) {
1141                                 add_pattern(&opt, argv[1], "-e option", 0,
1142                                             GREP_PATTERN);
1143                                 argv++;
1144                                 argc--;
1145                                 continue;
1146                         }
1147                         die(emsg_missing_argument, arg);
1148                 }
1149                 if (!strcmp("--full-name", arg)) {
1150                         opt.relative = 0;
1151                         continue;
1152                 }
1153                 if (!strcmp("--", arg)) {
1154                         /* later processing wants to have this at argv[1] */
1155                         argv--;
1156                         argc++;
1157                         break;
1158                 }
1159                 if (*arg == '-')
1160                         usage(builtin_grep_usage);
1161
1162                 /* First unrecognized non-option token */
1163                 if (!opt.pattern_list) {
1164                         add_pattern(&opt, arg, "command line", 0,
1165                                     GREP_PATTERN);
1166                         break;
1167                 }
1168                 else {
1169                         /* We are looking at the first path or rev;
1170                          * it is found at argv[1] after leaving the
1171                          * loop.
1172                          */
1173                         argc++; argv--;
1174                         break;
1175                 }
1176         }
1177
1178         if (!opt.pattern_list)
1179                 die("no pattern given.");
1180         if ((opt.regflags != REG_NEWLINE) && opt.fixed)
1181                 die("cannot mix --fixed-strings and regexp");
1182         if (!opt.fixed)
1183                 compile_patterns(&opt);
1184
1185         /* Check revs and then paths */
1186         for (i = 1; i < argc; i++) {
1187                 const char *arg = argv[i];
1188                 unsigned char sha1[20];
1189                 /* Is it a rev? */
1190                 if (!get_sha1(arg, sha1)) {
1191                         struct object *object = parse_object(sha1);
1192                         if (!object)
1193                                 die("bad object %s", arg);
1194                         add_object_array(object, arg, &list);
1195                         continue;
1196                 }
1197                 if (!strcmp(arg, "--")) {
1198                         i++;
1199                         seen_dashdash = 1;
1200                 }
1201                 break;
1202         }
1203
1204         /* The rest are paths */
1205         if (!seen_dashdash) {
1206                 int j;
1207                 for (j = i; j < argc; j++)
1208                         verify_filename(prefix, argv[j]);
1209         }
1210
1211         if (i < argc) {
1212                 paths = get_pathspec(prefix, argv + i);
1213                 if (opt.prefix_length && opt.relative) {
1214                         /* Make sure we do not get outside of paths */
1215                         for (i = 0; paths[i]; i++)
1216                                 if (strncmp(prefix, paths[i], opt.prefix_length))
1217                                         die("git-grep: cannot generate relative filenames containing '..'");
1218                 }
1219         }
1220         else if (prefix) {
1221                 paths = xcalloc(2, sizeof(const char *));
1222                 paths[0] = prefix;
1223                 paths[1] = NULL;
1224         }
1225
1226         if (!list.nr)
1227                 return !grep_cache(&opt, paths, cached);
1228
1229         if (cached)
1230                 die("both --cached and trees are given.");
1231
1232         for (i = 0; i < list.nr; i++) {
1233                 struct object *real_obj;
1234                 real_obj = deref_tag(list.objects[i].item, NULL, 0);
1235                 if (grep_object(&opt, paths, real_obj, list.objects[i].name))
1236                         hit = 1;
1237         }
1238         return !hit;
1239 }