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