grep.c

   1 #include "cache.h"
   2 #include "grep.h"
   3 #include "userdiff.h"
   4 #include "xdiff-interface.h"
   5
   6 static struct grep_pat *create_grep_pat(const char *pat, size_t patlen,
   7                                         const char *origin, int no,
   8                                         enum grep_pat_token t,
   9                                         enum grep_header_field field)
  10 {
  11         struct grep_pat *p = xcalloc(1, sizeof(*p));
  12         p->pattern = pat;
  13         p->patternlen = patlen;
  14         p->origin = origin;
  15         p->no = no;
  16         p->token = t;
  17         p->field = field;
  18         return p;
  19 }
  20
  21 static void do_append_grep_pat(struct grep_pat ***tail, struct grep_pat *p)
  22 {
  23         **tail = p;
  24         *tail = &p->next;
  25         p->next = NULL;
  26 }
  27
  28 void append_header_grep_pattern(struct grep_opt *opt,
  29                                 enum grep_header_field field, const char *pat)
  30 {
  31         struct grep_pat *p = create_grep_pat(pat, strlen(pat), "header", 0,
  32                                              GREP_PATTERN_HEAD, field);
  33         do_append_grep_pat(&opt->header_tail, p);
  34 }
  35
  36 void append_grep_pattern(struct grep_opt *opt, const char *pat,
  37                          const char *origin, int no, enum grep_pat_token t)
  38 {
  39         append_grep_pat(opt, pat, strlen(pat), origin, no, t);
  40 }
  41
  42 void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen,
  43                      const char *origin, int no, enum grep_pat_token t)
  44 {
  45         struct grep_pat *p = create_grep_pat(pat, patlen, origin, no, t, 0);
  46         do_append_grep_pat(&opt->pattern_tail, p);
  47 }
  48
  49 struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
  50 {
  51         struct grep_pat *pat;
  52         struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
  53         *ret = *opt;
  54
  55         ret->pattern_list = NULL;
  56         ret->pattern_tail = &ret->pattern_list;
  57
  58         for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
  59         {
  60                 if(pat->token == GREP_PATTERN_HEAD)
  61                         append_header_grep_pattern(ret, pat->field,
  62                                                    pat->pattern);
  63                 else
  64                         append_grep_pat(ret, pat->pattern, pat->patternlen,
  65                                         pat->origin, pat->no, pat->token);
  66         }
  67
  68         return ret;
  69 }
  70
  71 static NORETURN void compile_regexp_failed(const struct grep_pat *p,
  72                 const char *error)
  73 {
  74         char where[1024];
  75
  76         if (p->no)
  77                 sprintf(where, "In '%s' at %d, ", p->origin, p->no);
  78         else if (p->origin)
  79                 sprintf(where, "%s, ", p->origin);
  80         else
  81                 where[0] = 0;
  82
  83         die("%s'%s': %s", where, p->pattern, error);
  84 }
  85
  86 #ifdef USE_LIBPCRE
  87 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
  88 {
  89         const char *error;
  90         int erroffset;
  91         int options = 0;
  92
  93         if (opt->ignore_case)
  94                 options |= PCRE_CASELESS;
  95
  96         p->pcre_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
  97                         NULL);
  98         if (!p->pcre_regexp)
  99                 compile_regexp_failed(p, error);
 100
 101         p->pcre_extra_info = pcre_study(p->pcre_regexp, 0, &error);
 102         if (!p->pcre_extra_info && error)
 103                 die("%s", error);
 104 }
 105
 106 static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 107                 regmatch_t *match, int eflags)
 108 {
 109         int ovector[30], ret, flags = 0;
 110
 111         if (eflags & REG_NOTBOL)
 112                 flags |= PCRE_NOTBOL;
 113
 114         ret = pcre_exec(p->pcre_regexp, p->pcre_extra_info, line, eol - line,
 115                         0, flags, ovector, ARRAY_SIZE(ovector));
 116         if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
 117                 die("pcre_exec failed with error code %d", ret);
 118         if (ret > 0) {
 119                 ret = 0;
 120                 match->rm_so = ovector[0];
 121                 match->rm_eo = ovector[1];
 122         }
 123
 124         return ret;
 125 }
 126
 127 static void free_pcre_regexp(struct grep_pat *p)
 128 {
 129         pcre_free(p->pcre_regexp);
 130         pcre_free(p->pcre_extra_info);
 131 }
 132 #else /* !USE_LIBPCRE */
 133 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 134 {
 135         die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
 136 }
 137
 138 static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 139                 regmatch_t *match, int eflags)
 140 {
 141         return 1;
 142 }
 143
 144 static void free_pcre_regexp(struct grep_pat *p)
 145 {
 146 }
 147 #endif /* !USE_LIBPCRE */
 148
 149 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 150 {
 151         int err;
 152
 153         p->word_regexp = opt->word_regexp;
 154         p->ignore_case = opt->ignore_case;
 155         p->fixed = opt->fixed;
 156
 157         if (p->fixed)
 158                 return;
 159
 160         if (opt->pcre) {
 161                 compile_pcre_regexp(p, opt);
 162                 return;
 163         }
 164
 165         err = regcomp(&p->regexp, p->pattern, opt->regflags);
 166         if (err) {
 167                 char errbuf[1024];
 168                 regerror(err, &p->regexp, errbuf, 1024);
 169                 regfree(&p->regexp);
 170                 compile_regexp_failed(p, errbuf);
 171         }
 172 }
 173
 174 static struct grep_expr *compile_pattern_or(struct grep_pat **);
 175 static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
 176 {
 177         struct grep_pat *p;
 178         struct grep_expr *x;
 179
 180         p = *list;
 181         if (!p)
 182                 return NULL;
 183         switch (p->token) {
 184         case GREP_PATTERN: /* atom */
 185         case GREP_PATTERN_HEAD:
 186         case GREP_PATTERN_BODY:
 187                 x = xcalloc(1, sizeof (struct grep_expr));
 188                 x->node = GREP_NODE_ATOM;
 189                 x->u.atom = p;
 190                 *list = p->next;
 191                 return x;
 192         case GREP_OPEN_PAREN:
 193                 *list = p->next;
 194                 x = compile_pattern_or(list);
 195                 if (!*list || (*list)->token != GREP_CLOSE_PAREN)
 196                         die("unmatched parenthesis");
 197                 *list = (*list)->next;
 198                 return x;
 199         default:
 200                 return NULL;
 201         }
 202 }
 203
 204 static struct grep_expr *compile_pattern_not(struct grep_pat **list)
 205 {
 206         struct grep_pat *p;
 207         struct grep_expr *x;
 208
 209         p = *list;
 210         if (!p)
 211                 return NULL;
 212         switch (p->token) {
 213         case GREP_NOT:
 214                 if (!p->next)
 215                         die("--not not followed by pattern expression");
 216                 *list = p->next;
 217                 x = xcalloc(1, sizeof (struct grep_expr));
 218                 x->node = GREP_NODE_NOT;
 219                 x->u.unary = compile_pattern_not(list);
 220                 if (!x->u.unary)
 221                         die("--not followed by non pattern expression");
 222                 return x;
 223         default:
 224                 return compile_pattern_atom(list);
 225         }
 226 }
 227
 228 static struct grep_expr *compile_pattern_and(struct grep_pat **list)
 229 {
 230         struct grep_pat *p;
 231         struct grep_expr *x, *y, *z;
 232
 233         x = compile_pattern_not(list);
 234         p = *list;
 235         if (p && p->token == GREP_AND) {
 236                 if (!p->next)
 237                         die("--and not followed by pattern expression");
 238                 *list = p->next;
 239                 y = compile_pattern_and(list);
 240                 if (!y)
 241                         die("--and not followed by pattern expression");
 242                 z = xcalloc(1, sizeof (struct grep_expr));
 243                 z->node = GREP_NODE_AND;
 244                 z->u.binary.left = x;
 245                 z->u.binary.right = y;
 246                 return z;
 247         }
 248         return x;
 249 }
 250
 251 static struct grep_expr *compile_pattern_or(struct grep_pat **list)
 252 {
 253         struct grep_pat *p;
 254         struct grep_expr *x, *y, *z;
 255
 256         x = compile_pattern_and(list);
 257         p = *list;
 258         if (x && p && p->token != GREP_CLOSE_PAREN) {
 259                 y = compile_pattern_or(list);
 260                 if (!y)
 261                         die("not a pattern expression %s", p->pattern);
 262                 z = xcalloc(1, sizeof (struct grep_expr));
 263                 z->node = GREP_NODE_OR;
 264                 z->u.binary.left = x;
 265                 z->u.binary.right = y;
 266                 return z;
 267         }
 268         return x;
 269 }
 270
 271 static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
 272 {
 273         return compile_pattern_or(list);
 274 }
 275
 276 static struct grep_expr *grep_true_expr(void)
 277 {
 278         struct grep_expr *z = xcalloc(1, sizeof(*z));
 279         z->node = GREP_NODE_TRUE;
 280         return z;
 281 }
 282
 283 static struct grep_expr *grep_or_expr(struct grep_expr *left, struct grep_expr *right)
 284 {
 285         struct grep_expr *z = xcalloc(1, sizeof(*z));
 286         z->node = GREP_NODE_OR;
 287         z->u.binary.left = left;
 288         z->u.binary.right = right;
 289         return z;
 290 }
 291
 292 static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
 293 {
 294         struct grep_pat *p;
 295         struct grep_expr *header_expr;
 296         struct grep_expr *(header_group[GREP_HEADER_FIELD_MAX]);
 297         enum grep_header_field fld;
 298
 299         if (!opt->header_list)
 300                 return NULL;
 301         p = opt->header_list;
 302         for (p = opt->header_list; p; p = p->next) {
 303                 if (p->token != GREP_PATTERN_HEAD)
 304                         die("bug: a non-header pattern in grep header list.");
 305                 if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
 306                         die("bug: unknown header field %d", p->field);
 307                 compile_regexp(p, opt);
 308         }
 309
 310         for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++)
 311                 header_group[fld] = NULL;
 312
 313         for (p = opt->header_list; p; p = p->next) {
 314                 struct grep_expr *h;
 315                 struct grep_pat *pp = p;
 316
 317                 h = compile_pattern_atom(&pp);
 318                 if (!h || pp != p->next)
 319                         die("bug: malformed header expr");
 320                 if (!header_group[p->field]) {
 321                         header_group[p->field] = h;
 322                         continue;
 323                 }
 324                 header_group[p->field] = grep_or_expr(h, header_group[p->field]);
 325         }
 326
 327         header_expr = NULL;
 328
 329         for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++) {
 330                 if (!header_group[fld])
 331                         continue;
 332                 if (!header_expr)
 333                         header_expr = grep_true_expr();
 334                 header_expr = grep_or_expr(header_group[fld], header_expr);
 335         }
 336         return header_expr;
 337 }
 338
 339 void compile_grep_patterns(struct grep_opt *opt)
 340 {
 341         struct grep_pat *p;
 342         struct grep_expr *header_expr = prep_header_patterns(opt);
 343
 344         for (p = opt->pattern_list; p; p = p->next) {
 345                 switch (p->token) {
 346                 case GREP_PATTERN: /* atom */
 347                 case GREP_PATTERN_HEAD:
 348                 case GREP_PATTERN_BODY:
 349                         compile_regexp(p, opt);
 350                         break;
 351                 default:
 352                         opt->extended = 1;
 353                         break;
 354                 }
 355         }
 356
 357         if (opt->all_match || header_expr)
 358                 opt->extended = 1;
 359         else if (!opt->extended)
 360                 return;
 361
 362         p = opt->pattern_list;
 363         if (p)
 364                 opt->pattern_expression = compile_pattern_expr(&p);
 365         if (p)
 366                 die("incomplete pattern expression: %s", p->pattern);
 367
 368         if (!header_expr)
 369                 return;
 370
 371         if (!opt->pattern_expression)
 372                 opt->pattern_expression = header_expr;
 373         else
 374                 opt->pattern_expression = grep_or_expr(opt->pattern_expression,
 375                                                        header_expr);
 376         opt->all_match = 1;
 377 }
 378
 379 static void free_pattern_expr(struct grep_expr *x)
 380 {
 381         switch (x->node) {
 382         case GREP_NODE_TRUE:
 383         case GREP_NODE_ATOM:
 384                 break;
 385         case GREP_NODE_NOT:
 386                 free_pattern_expr(x->u.unary);
 387                 break;
 388         case GREP_NODE_AND:
 389         case GREP_NODE_OR:
 390                 free_pattern_expr(x->u.binary.left);
 391                 free_pattern_expr(x->u.binary.right);
 392                 break;
 393         }
 394         free(x);
 395 }
 396
 397 void free_grep_patterns(struct grep_opt *opt)
 398 {
 399         struct grep_pat *p, *n;
 400
 401         for (p = opt->pattern_list; p; p = n) {
 402                 n = p->next;
 403                 switch (p->token) {
 404                 case GREP_PATTERN: /* atom */
 405                 case GREP_PATTERN_HEAD:
 406                 case GREP_PATTERN_BODY:
 407                         if (p->pcre_regexp)
 408                                 free_pcre_regexp(p);
 409                         else
 410                                 regfree(&p->regexp);
 411                         break;
 412                 default:
 413                         break;
 414                 }
 415                 free(p);
 416         }
 417
 418         if (!opt->extended)
 419                 return;
 420         free_pattern_expr(opt->pattern_expression);
 421 }
 422
 423 static char *end_of_line(char *cp, unsigned long *left)
 424 {
 425         unsigned long l = *left;
 426         while (l && *cp != '\n') {
 427                 l--;
 428                 cp++;
 429         }
 430         *left = l;
 431         return cp;
 432 }
 433
 434 static int word_char(char ch)
 435 {
 436         return isalnum(ch) || ch == '_';
 437 }
 438
 439 static void output_color(struct grep_opt *opt, const void *data, size_t size,
 440                          const char *color)
 441 {
 442         if (opt->color && color && color[0]) {
 443                 opt->output(opt, color, strlen(color));
 444                 opt->output(opt, data, size);
 445                 opt->output(opt, GIT_COLOR_RESET, strlen(GIT_COLOR_RESET));
 446         } else
 447                 opt->output(opt, data, size);
 448 }
 449
 450 static void output_sep(struct grep_opt *opt, char sign)
 451 {
 452         if (opt->null_following_name)
 453                 opt->output(opt, "\0", 1);
 454         else
 455                 output_color(opt, &sign, 1, opt->color_sep);
 456 }
 457
 458 static void show_name(struct grep_opt *opt, const char *name)
 459 {
 460         output_color(opt, name, strlen(name), opt->color_filename);
 461         opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 462 }
 463
 464 static int fixmatch(struct grep_pat *p, char *line, char *eol,
 465                     regmatch_t *match)
 466 {
 467         char *hit;
 468
 469         if (p->ignore_case) {
 470                 char *s = line;
 471                 do {
 472                         hit = strcasestr(s, p->pattern);
 473                         if (hit)
 474                                 break;
 475                         s += strlen(s) + 1;
 476                 } while (s < eol);
 477         } else
 478                 hit = memmem(line, eol - line, p->pattern, p->patternlen);
 479
 480         if (!hit) {
 481                 match->rm_so = match->rm_eo = -1;
 482                 return REG_NOMATCH;
 483         }
 484         else {
 485                 match->rm_so = hit - line;
 486                 match->rm_eo = match->rm_so + p->patternlen;
 487                 return 0;
 488         }
 489 }
 490
 491 static int regmatch(const regex_t *preg, char *line, char *eol,
 492                     regmatch_t *match, int eflags)
 493 {
 494 #ifdef REG_STARTEND
 495         match->rm_so = 0;
 496         match->rm_eo = eol - line;
 497         eflags |= REG_STARTEND;
 498 #endif
 499         return regexec(preg, line, 1, match, eflags);
 500 }
 501
 502 static int patmatch(struct grep_pat *p, char *line, char *eol,
 503                     regmatch_t *match, int eflags)
 504 {
 505         int hit;
 506
 507         if (p->fixed)
 508                 hit = !fixmatch(p, line, eol, match);
 509         else if (p->pcre_regexp)
 510                 hit = !pcrematch(p, line, eol, match, eflags);
 511         else
 512                 hit = !regmatch(&p->regexp, line, eol, match, eflags);
 513
 514         return hit;
 515 }
 516
 517 static int strip_timestamp(char *bol, char **eol_p)
 518 {
 519         char *eol = *eol_p;
 520         int ch;
 521
 522         while (bol < --eol) {
 523                 if (*eol != '>')
 524                         continue;
 525                 *eol_p = ++eol;
 526                 ch = *eol;
 527                 *eol = '\0';
 528                 return ch;
 529         }
 530         return 0;
 531 }
 532
 533 static struct {
 534         const char *field;
 535         size_t len;
 536 } header_field[] = {
 537         { "author ", 7 },
 538         { "committer ", 10 },
 539 };
 540
 541 static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 542                              enum grep_context ctx,
 543                              regmatch_t *pmatch, int eflags)
 544 {
 545         int hit = 0;
 546         int saved_ch = 0;
 547         const char *start = bol;
 548
 549         if ((p->token != GREP_PATTERN) &&
 550             ((p->token == GREP_PATTERN_HEAD) != (ctx == GREP_CONTEXT_HEAD)))
 551                 return 0;
 552
 553         if (p->token == GREP_PATTERN_HEAD) {
 554                 const char *field;
 555                 size_t len;
 556                 assert(p->field < ARRAY_SIZE(header_field));
 557                 field = header_field[p->field].field;
 558                 len = header_field[p->field].len;
 559                 if (strncmp(bol, field, len))
 560                         return 0;
 561                 bol += len;
 562                 saved_ch = strip_timestamp(bol, &eol);
 563         }
 564
 565  again:
 566         hit = patmatch(p, bol, eol, pmatch, eflags);
 567
 568         if (hit && p->word_regexp) {
 569                 if ((pmatch[0].rm_so < 0) ||
 570                     (eol - bol) < pmatch[0].rm_so ||
 571                     (pmatch[0].rm_eo < 0) ||
 572                     (eol - bol) < pmatch[0].rm_eo)
 573                         die("regexp returned nonsense");
 574
 575                 /* Match beginning must be either beginning of the
 576                  * line, or at word boundary (i.e. the last char must
 577                  * not be a word char).  Similarly, match end must be
 578                  * either end of the line, or at word boundary
 579                  * (i.e. the next char must not be a word char).
 580                  */
 581                 if ( ((pmatch[0].rm_so == 0) ||
 582                       !word_char(bol[pmatch[0].rm_so-1])) &&
 583                      ((pmatch[0].rm_eo == (eol-bol)) ||
 584                       !word_char(bol[pmatch[0].rm_eo])) )
 585                         ;
 586                 else
 587                         hit = 0;
 588
 589                 /* Words consist of at least one character. */
 590                 if (pmatch->rm_so == pmatch->rm_eo)
 591                         hit = 0;
 592
 593                 if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
 594                         /* There could be more than one match on the
 595                          * line, and the first match might not be
 596                          * strict word match.  But later ones could be!
 597                          * Forward to the next possible start, i.e. the
 598                          * next position following a non-word char.
 599                          */
 600                         bol = pmatch[0].rm_so + bol + 1;
 601                         while (word_char(bol[-1]) && bol < eol)
 602                                 bol++;
 603                         eflags |= REG_NOTBOL;
 604                         if (bol < eol)
 605                                 goto again;
 606                 }
 607         }
 608         if (p->token == GREP_PATTERN_HEAD && saved_ch)
 609                 *eol = saved_ch;
 610         if (hit) {
 611                 pmatch[0].rm_so += bol - start;
 612                 pmatch[0].rm_eo += bol - start;
 613         }
 614         return hit;
 615 }
 616
 617 static int match_expr_eval(struct grep_expr *x, char *bol, char *eol,
 618                            enum grep_context ctx, int collect_hits)
 619 {
 620         int h = 0;
 621         regmatch_t match;
 622
 623         if (!x)
 624                 die("Not a valid grep expression");
 625         switch (x->node) {
 626         case GREP_NODE_TRUE:
 627                 h = 1;
 628                 break;
 629         case GREP_NODE_ATOM:
 630                 h = match_one_pattern(x->u.atom, bol, eol, ctx, &match, 0);
 631                 break;
 632         case GREP_NODE_NOT:
 633                 h = !match_expr_eval(x->u.unary, bol, eol, ctx, 0);
 634                 break;
 635         case GREP_NODE_AND:
 636                 if (!match_expr_eval(x->u.binary.left, bol, eol, ctx, 0))
 637                         return 0;
 638                 h = match_expr_eval(x->u.binary.right, bol, eol, ctx, 0);
 639                 break;
 640         case GREP_NODE_OR:
 641                 if (!collect_hits)
 642                         return (match_expr_eval(x->u.binary.left,
 643                                                 bol, eol, ctx, 0) ||
 644                                 match_expr_eval(x->u.binary.right,
 645                                                 bol, eol, ctx, 0));
 646                 h = match_expr_eval(x->u.binary.left, bol, eol, ctx, 0);
 647                 x->u.binary.left->hit |= h;
 648                 h |= match_expr_eval(x->u.binary.right, bol, eol, ctx, 1);
 649                 break;
 650         default:
 651                 die("Unexpected node type (internal error) %d", x->node);
 652         }
 653         if (collect_hits)
 654                 x->hit |= h;
 655         return h;
 656 }
 657
 658 static int match_expr(struct grep_opt *opt, char *bol, char *eol,
 659                       enum grep_context ctx, int collect_hits)
 660 {
 661         struct grep_expr *x = opt->pattern_expression;
 662         return match_expr_eval(x, bol, eol, ctx, collect_hits);
 663 }
 664
 665 static int match_line(struct grep_opt *opt, char *bol, char *eol,
 666                       enum grep_context ctx, int collect_hits)
 667 {
 668         struct grep_pat *p;
 669         regmatch_t match;
 670
 671         if (opt->extended)
 672                 return match_expr(opt, bol, eol, ctx, collect_hits);
 673
 674         /* we do not call with collect_hits without being extended */
 675         for (p = opt->pattern_list; p; p = p->next) {
 676                 if (match_one_pattern(p, bol, eol, ctx, &match, 0))
 677                         return 1;
 678         }
 679         return 0;
 680 }
 681
 682 static int match_next_pattern(struct grep_pat *p, char *bol, char *eol,
 683                               enum grep_context ctx,
 684                               regmatch_t *pmatch, int eflags)
 685 {
 686         regmatch_t match;
 687
 688         if (!match_one_pattern(p, bol, eol, ctx, &match, eflags))
 689                 return 0;
 690         if (match.rm_so < 0 || match.rm_eo < 0)
 691                 return 0;
 692         if (pmatch->rm_so >= 0 && pmatch->rm_eo >= 0) {
 693                 if (match.rm_so > pmatch->rm_so)
 694                         return 1;
 695                 if (match.rm_so == pmatch->rm_so && match.rm_eo < pmatch->rm_eo)
 696                         return 1;
 697         }
 698         pmatch->rm_so = match.rm_so;
 699         pmatch->rm_eo = match.rm_eo;
 700         return 1;
 701 }
 702
 703 static int next_match(struct grep_opt *opt, char *bol, char *eol,
 704                       enum grep_context ctx, regmatch_t *pmatch, int eflags)
 705 {
 706         struct grep_pat *p;
 707         int hit = 0;
 708
 709         pmatch->rm_so = pmatch->rm_eo = -1;
 710         if (bol < eol) {
 711                 for (p = opt->pattern_list; p; p = p->next) {
 712                         switch (p->token) {
 713                         case GREP_PATTERN: /* atom */
 714                         case GREP_PATTERN_HEAD:
 715                         case GREP_PATTERN_BODY:
 716                                 hit |= match_next_pattern(p, bol, eol, ctx,
 717                                                           pmatch, eflags);
 718                                 break;
 719                         default:
 720                                 break;
 721                         }
 722                 }
 723         }
 724         return hit;
 725 }
 726
 727 static void show_line(struct grep_opt *opt, char *bol, char *eol,
 728                       const char *name, unsigned lno, char sign)
 729 {
 730         int rest = eol - bol;
 731         char *line_color = NULL;
 732
 733         if (opt->pre_context || opt->post_context) {
 734                 if (opt->last_shown == 0) {
 735                         if (opt->show_hunk_mark) {
 736                                 output_color(opt, "--", 2, opt->color_sep);
 737                                 opt->output(opt, "\n", 1);
 738                         }
 739                 } else if (lno > opt->last_shown + 1) {
 740                         output_color(opt, "--", 2, opt->color_sep);
 741                         opt->output(opt, "\n", 1);
 742                 }
 743         }
 744         opt->last_shown = lno;
 745
 746         if (opt->pathname) {
 747                 output_color(opt, name, strlen(name), opt->color_filename);
 748                 output_sep(opt, sign);
 749         }
 750         if (opt->linenum) {
 751                 char buf[32];
 752                 snprintf(buf, sizeof(buf), "%d", lno);
 753                 output_color(opt, buf, strlen(buf), opt->color_lineno);
 754                 output_sep(opt, sign);
 755         }
 756         if (opt->color) {
 757                 regmatch_t match;
 758                 enum grep_context ctx = GREP_CONTEXT_BODY;
 759                 int ch = *eol;
 760                 int eflags = 0;
 761
 762                 if (sign == ':')
 763                         line_color = opt->color_selected;
 764                 else if (sign == '-')
 765                         line_color = opt->color_context;
 766                 else if (sign == '=')
 767                         line_color = opt->color_function;
 768                 *eol = '\0';
 769                 while (next_match(opt, bol, eol, ctx, &match, eflags)) {
 770                         if (match.rm_so == match.rm_eo)
 771                                 break;
 772
 773                         output_color(opt, bol, match.rm_so, line_color);
 774                         output_color(opt, bol + match.rm_so,
 775                                      match.rm_eo - match.rm_so,
 776                                      opt->color_match);
 777                         bol += match.rm_eo;
 778                         rest -= match.rm_eo;
 779                         eflags = REG_NOTBOL;
 780                 }
 781                 *eol = ch;
 782         }
 783         output_color(opt, bol, rest, line_color);
 784         opt->output(opt, "\n", 1);
 785 }
 786
 787 static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
 788 {
 789         xdemitconf_t *xecfg = opt->priv;
 790         if (xecfg && xecfg->find_func) {
 791                 char buf[1];
 792                 return xecfg->find_func(bol, eol - bol, buf, 1,
 793                                         xecfg->find_func_priv) >= 0;
 794         }
 795
 796         if (bol == eol)
 797                 return 0;
 798         if (isalpha(*bol) || *bol == '_' || *bol == '$')
 799                 return 1;
 800         return 0;
 801 }
 802
 803 static void show_funcname_line(struct grep_opt *opt, const char *name,
 804                                char *buf, char *bol, unsigned lno)
 805 {
 806         while (bol > buf) {
 807                 char *eol = --bol;
 808
 809                 while (bol > buf && bol[-1] != '\n')
 810                         bol--;
 811                 lno--;
 812
 813                 if (lno <= opt->last_shown)
 814                         break;
 815
 816                 if (match_funcname(opt, bol, eol)) {
 817                         show_line(opt, bol, eol, name, lno, '=');
 818                         break;
 819                 }
 820         }
 821 }
 822
 823 static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
 824                              char *bol, unsigned lno)
 825 {
 826         unsigned cur = lno, from = 1, funcname_lno = 0;
 827         int funcname_needed = opt->funcname;
 828
 829         if (opt->pre_context < lno)
 830                 from = lno - opt->pre_context;
 831         if (from <= opt->last_shown)
 832                 from = opt->last_shown + 1;
 833
 834         /* Rewind. */
 835         while (bol > buf && cur > from) {
 836                 char *eol = --bol;
 837
 838                 while (bol > buf && bol[-1] != '\n')
 839                         bol--;
 840                 cur--;
 841                 if (funcname_needed && match_funcname(opt, bol, eol)) {
 842                         funcname_lno = cur;
 843                         funcname_needed = 0;
 844                 }
 845         }
 846
 847         /* We need to look even further back to find a function signature. */
 848         if (opt->funcname && funcname_needed)
 849                 show_funcname_line(opt, name, buf, bol, cur);
 850
 851         /* Back forward. */
 852         while (cur < lno) {
 853                 char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';
 854
 855                 while (*eol != '\n')
 856                         eol++;
 857                 show_line(opt, bol, eol, name, cur, sign);
 858                 bol = eol + 1;
 859                 cur++;
 860         }
 861 }
 862
 863 static int should_lookahead(struct grep_opt *opt)
 864 {
 865         struct grep_pat *p;
 866
 867         if (opt->extended)
 868                 return 0; /* punt for too complex stuff */
 869         if (opt->invert)
 870                 return 0;
 871         for (p = opt->pattern_list; p; p = p->next) {
 872                 if (p->token != GREP_PATTERN)
 873                         return 0; /* punt for "header only" and stuff */
 874         }
 875         return 1;
 876 }
 877
 878 static int look_ahead(struct grep_opt *opt,
 879                       unsigned long *left_p,
 880                       unsigned *lno_p,
 881                       char **bol_p)
 882 {
 883         unsigned lno = *lno_p;
 884         char *bol = *bol_p;
 885         struct grep_pat *p;
 886         char *sp, *last_bol;
 887         regoff_t earliest = -1;
 888
 889         for (p = opt->pattern_list; p; p = p->next) {
 890                 int hit;
 891                 regmatch_t m;
 892
 893                 hit = patmatch(p, bol, bol + *left_p, &m, 0);
 894                 if (!hit || m.rm_so < 0 || m.rm_eo < 0)
 895                         continue;
 896                 if (earliest < 0 || m.rm_so < earliest)
 897                         earliest = m.rm_so;
 898         }
 899
 900         if (earliest < 0) {
 901                 *bol_p = bol + *left_p;
 902                 *left_p = 0;
 903                 return 1;
 904         }
 905         for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
 906                 ; /* find the beginning of the line */
 907         last_bol = sp;
 908
 909         for (sp = bol; sp < last_bol; sp++) {
 910                 if (*sp == '\n')
 911                         lno++;
 912         }
 913         *left_p -= last_bol - bol;
 914         *bol_p = last_bol;
 915         *lno_p = lno;
 916         return 0;
 917 }
 918
 919 int grep_threads_ok(const struct grep_opt *opt)
 920 {
 921         /* If this condition is true, then we may use the attribute
 922          * machinery in grep_buffer_1. The attribute code is not
 923          * thread safe, so we disable the use of threads.
 924          */
 925         if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 926             !opt->name_only)
 927                 return 0;
 928
 929         return 1;
 930 }
 931
 932 static void std_output(struct grep_opt *opt, const void *buf, size_t size)
 933 {
 934         fwrite(buf, size, 1, stdout);
 935 }
 936
 937 static int grep_buffer_1(struct grep_opt *opt, const char *name,
 938                          char *buf, unsigned long size, int collect_hits)
 939 {
 940         char *bol = buf;
 941         unsigned long left = size;
 942         unsigned lno = 1;
 943         unsigned last_hit = 0;
 944         int binary_match_only = 0;
 945         unsigned count = 0;
 946         int try_lookahead = 0;
 947         enum grep_context ctx = GREP_CONTEXT_HEAD;
 948         xdemitconf_t xecfg;
 949
 950         if (!opt->output)
 951                 opt->output = std_output;
 952
 953         if (opt->last_shown && (opt->pre_context || opt->post_context) &&
 954             opt->output == std_output)
 955                 opt->show_hunk_mark = 1;
 956         opt->last_shown = 0;
 957
 958         switch (opt->binary) {
 959         case GREP_BINARY_DEFAULT:
 960                 if (buffer_is_binary(buf, size))
 961                         binary_match_only = 1;
 962                 break;
 963         case GREP_BINARY_NOMATCH:
 964                 if (buffer_is_binary(buf, size))
 965                         return 0; /* Assume unmatch */
 966                 break;
 967         case GREP_BINARY_TEXT:
 968                 break;
 969         default:
 970                 die("bug: unknown binary handling mode");
 971         }
 972
 973         memset(&xecfg, 0, sizeof(xecfg));
 974         if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 975             !opt->name_only && !binary_match_only && !collect_hits) {
 976                 struct userdiff_driver *drv = userdiff_find_by_path(name);
 977                 if (drv && drv->funcname.pattern) {
 978                         const struct userdiff_funcname *pe = &drv->funcname;
 979                         xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
 980                         opt->priv = &xecfg;
 981                 }
 982         }
 983         try_lookahead = should_lookahead(opt);
 984
 985         while (left) {
 986                 char *eol, ch;
 987                 int hit;
 988
 989                 /*
 990                  * look_ahead() skips quickly to the line that possibly
 991                  * has the next hit; don't call it if we need to do
 992                  * something more than just skipping the current line
 993                  * in response to an unmatch for the current line.  E.g.
 994                  * inside a post-context window, we will show the current
 995                  * line as a context around the previous hit when it
 996                  * doesn't hit.
 997                  */
 998                 if (try_lookahead
 999                     && !(last_hit
1000                          && lno <= last_hit + opt->post_context)
1001                     && look_ahead(opt, &left, &lno, &bol))
1002                         break;
1003                 eol = end_of_line(bol, &left);
1004                 ch = *eol;
1005                 *eol = 0;
1006
1007                 if ((ctx == GREP_CONTEXT_HEAD) && (eol == bol))
1008                         ctx = GREP_CONTEXT_BODY;
1009
1010                 hit = match_line(opt, bol, eol, ctx, collect_hits);
1011                 *eol = ch;
1012
1013                 if (collect_hits)
1014                         goto next_line;
1015
1016                 /* "grep -v -e foo -e bla" should list lines
1017                  * that do not have either, so inversion should
1018                  * be done outside.
1019                  */
1020                 if (opt->invert)
1021                         hit = !hit;
1022                 if (opt->unmatch_name_only) {
1023                         if (hit)
1024                                 return 0;
1025                         goto next_line;
1026                 }
1027                 if (hit) {
1028                         count++;
1029                         if (opt->status_only)
1030                                 return 1;
1031                         if (opt->name_only) {
1032                                 show_name(opt, name);
1033                                 return 1;
1034                         }
1035                         if (opt->count)
1036                                 goto next_line;
1037                         if (binary_match_only) {
1038                                 opt->output(opt, "Binary file ", 12);
1039                                 output_color(opt, name, strlen(name),
1040                                              opt->color_filename);
1041                                 opt->output(opt, " matches\n", 9);
1042                                 return 1;
1043                         }
1044                         /* Hit at this line.  If we haven't shown the
1045                          * pre-context lines, we would need to show them.
1046                          */
1047                         if (opt->pre_context)
1048                                 show_pre_context(opt, name, buf, bol, lno);
1049                         else if (opt->funcname)
1050                                 show_funcname_line(opt, name, buf, bol, lno);
1051                         show_line(opt, bol, eol, name, lno, ':');
1052                         last_hit = lno;
1053                 }
1054                 else if (last_hit &&
1055                          lno <= last_hit + opt->post_context) {
1056                         /* If the last hit is within the post context,
1057                          * we need to show this line.
1058                          */
1059                         show_line(opt, bol, eol, name, lno, '-');
1060                 }
1061
1062         next_line:
1063                 bol = eol + 1;
1064                 if (!left)
1065                         break;
1066                 left--;
1067                 lno++;
1068         }
1069
1070         if (collect_hits)
1071                 return 0;
1072
1073         if (opt->status_only)
1074                 return 0;
1075         if (opt->unmatch_name_only) {
1076                 /* We did not see any hit, so we want to show this */
1077                 show_name(opt, name);
1078                 return 1;
1079         }
1080
1081         xdiff_clear_find_func(&xecfg);
1082         opt->priv = NULL;
1083
1084         /* NEEDSWORK:
1085          * The real "grep -c foo *.c" gives many "bar.c:0" lines,
1086          * which feels mostly useless but sometimes useful.  Maybe
1087          * make it another option?  For now suppress them.
1088          */
1089         if (opt->count && count) {
1090                 char buf[32];
1091                 output_color(opt, name, strlen(name), opt->color_filename);
1092                 output_sep(opt, ':');
1093                 snprintf(buf, sizeof(buf), "%u\n", count);
1094                 opt->output(opt, buf, strlen(buf));
1095                 return 1;
1096         }
1097         return !!last_hit;
1098 }
1099
1100 static void clr_hit_marker(struct grep_expr *x)
1101 {
1102         /* All-hit markers are meaningful only at the very top level
1103          * OR node.
1104          */
1105         while (1) {
1106                 x->hit = 0;
1107                 if (x->node != GREP_NODE_OR)
1108                         return;
1109                 x->u.binary.left->hit = 0;
1110                 x = x->u.binary.right;
1111         }
1112 }
1113
1114 static int chk_hit_marker(struct grep_expr *x)
1115 {
1116         /* Top level nodes have hit markers.  See if they all are hits */
1117         while (1) {
1118                 if (x->node != GREP_NODE_OR)
1119                         return x->hit;
1120                 if (!x->u.binary.left->hit)
1121                         return 0;
1122                 x = x->u.binary.right;
1123         }
1124 }
1125
1126 int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsigned long size)
1127 {
1128         /*
1129          * we do not have to do the two-pass grep when we do not check
1130          * buffer-wide "all-match".
1131          */
1132         if (!opt->all_match)
1133                 return grep_buffer_1(opt, name, buf, size, 0);
1134
1135         /* Otherwise the toplevel "or" terms hit a bit differently.
1136          * We first clear hit markers from them.
1137          */
1138         clr_hit_marker(opt->pattern_expression);
1139         grep_buffer_1(opt, name, buf, size, 1);
1140
1141         if (!chk_hit_marker(opt->pattern_expression))
1142                 return 0;
1143
1144         return grep_buffer_1(opt, name, buf, size, 0);
1145 }