grep.c

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