Andrew's git / gitweb.git / grep.c
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grep.con commit xdiff/xhistogram: drop need for additional variable (6486a84)
   1#include "cache.h"
   2#include "grep.h"
   3#include "userdiff.h"
   4#include "xdiff-interface.h"
   5
   6void 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->patternlen = strlen(pat);
  11        p->origin = "header";
  12        p->no = 0;
  13        p->token = GREP_PATTERN_HEAD;
  14        p->field = field;
  15        *opt->header_tail = p;
  16        opt->header_tail = &p->next;
  17        p->next = NULL;
  18}
  19
  20void append_grep_pattern(struct grep_opt *opt, const char *pat,
  21                         const char *origin, int no, enum grep_pat_token t)
  22{
  23        append_grep_pat(opt, pat, strlen(pat), origin, no, t);
  24}
  25
  26void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen,
  27                     const char *origin, int no, enum grep_pat_token t)
  28{
  29        struct grep_pat *p = xcalloc(1, sizeof(*p));
  30        p->pattern = pat;
  31        p->patternlen = patlen;
  32        p->origin = origin;
  33        p->no = no;
  34        p->token = t;
  35        *opt->pattern_tail = p;
  36        opt->pattern_tail = &p->next;
  37        p->next = NULL;
  38}
  39
  40struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
  41{
  42        struct grep_pat *pat;
  43        struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
  44        *ret = *opt;
  45
  46        ret->pattern_list = NULL;
  47        ret->pattern_tail = &ret->pattern_list;
  48
  49        for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
  50        {
  51                if(pat->token == GREP_PATTERN_HEAD)
  52                        append_header_grep_pattern(ret, pat->field,
  53                                                   pat->pattern);
  54                else
  55                        append_grep_pat(ret, pat->pattern, pat->patternlen,
  56                                        pat->origin, pat->no, pat->token);
  57        }
  58
  59        return ret;
  60}
  61
  62static NORETURN void compile_regexp_failed(const struct grep_pat *p,
  63                const char *error)
  64{
  65        char where[1024];
  66
  67        if (p->no)
  68                sprintf(where, "In '%s' at %d, ", p->origin, p->no);
  69        else if (p->origin)
  70                sprintf(where, "%s, ", p->origin);
  71        else
  72                where[0] = 0;
  73
  74        die("%s'%s': %s", where, p->pattern, error);
  75}
  76
  77#ifdef USE_LIBPCRE
  78static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
  79{
  80        const char *error;
  81        int erroffset;
  82        int options = 0;
  83
  84        if (opt->ignore_case)
  85                options |= PCRE_CASELESS;
  86
  87        p->pcre_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
  88                        NULL);
  89        if (!p->pcre_regexp)
  90                compile_regexp_failed(p, error);
  91
  92        p->pcre_extra_info = pcre_study(p->pcre_regexp, 0, &error);
  93        if (!p->pcre_extra_info && error)
  94                die("%s", error);
  95}
  96
  97static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
  98                regmatch_t *match, int eflags)
  99{
 100        int ovector[30], ret, flags = 0;
 101
 102        if (eflags & REG_NOTBOL)
 103                flags |= PCRE_NOTBOL;
 104
 105        ret = pcre_exec(p->pcre_regexp, p->pcre_extra_info, line, eol - line,
 106                        0, flags, ovector, ARRAY_SIZE(ovector));
 107        if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
 108                die("pcre_exec failed with error code %d", ret);
 109        if (ret > 0) {
 110                ret = 0;
 111                match->rm_so = ovector[0];
 112                match->rm_eo = ovector[1];
 113        }
 114
 115        return ret;
 116}
 117
 118static void free_pcre_regexp(struct grep_pat *p)
 119{
 120        pcre_free(p->pcre_regexp);
 121        pcre_free(p->pcre_extra_info);
 122}
 123#else /* !USE_LIBPCRE */
 124static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 125{
 126        die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
 127}
 128
 129static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 130                regmatch_t *match, int eflags)
 131{
 132        return 1;
 133}
 134
 135static void free_pcre_regexp(struct grep_pat *p)
 136{
 137}
 138#endif /* !USE_LIBPCRE */
 139
 140static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 141{
 142        int err;
 143
 144        p->word_regexp = opt->word_regexp;
 145        p->ignore_case = opt->ignore_case;
 146        p->fixed = opt->fixed;
 147
 148        if (p->fixed)
 149                return;
 150
 151        if (opt->pcre) {
 152                compile_pcre_regexp(p, opt);
 153                return;
 154        }
 155
 156        err = regcomp(&p->regexp, p->pattern, opt->regflags);
 157        if (err) {
 158                char errbuf[1024];
 159                regerror(err, &p->regexp, errbuf, 1024);
 160                regfree(&p->regexp);
 161                compile_regexp_failed(p, errbuf);
 162        }
 163}
 164
 165static struct grep_expr *compile_pattern_or(struct grep_pat **);
 166static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
 167{
 168        struct grep_pat *p;
 169        struct grep_expr *x;
 170
 171        p = *list;
 172        if (!p)
 173                return NULL;
 174        switch (p->token) {
 175        case GREP_PATTERN: /* atom */
 176        case GREP_PATTERN_HEAD:
 177        case GREP_PATTERN_BODY:
 178                x = xcalloc(1, sizeof (struct grep_expr));
 179                x->node = GREP_NODE_ATOM;
 180                x->u.atom = p;
 181                *list = p->next;
 182                return x;
 183        case GREP_OPEN_PAREN:
 184                *list = p->next;
 185                x = compile_pattern_or(list);
 186                if (!*list || (*list)->token != GREP_CLOSE_PAREN)
 187                        die("unmatched parenthesis");
 188                *list = (*list)->next;
 189                return x;
 190        default:
 191                return NULL;
 192        }
 193}
 194
 195static struct grep_expr *compile_pattern_not(struct grep_pat **list)
 196{
 197        struct grep_pat *p;
 198        struct grep_expr *x;
 199
 200        p = *list;
 201        if (!p)
 202                return NULL;
 203        switch (p->token) {
 204        case GREP_NOT:
 205                if (!p->next)
 206                        die("--not not followed by pattern expression");
 207                *list = p->next;
 208                x = xcalloc(1, sizeof (struct grep_expr));
 209                x->node = GREP_NODE_NOT;
 210                x->u.unary = compile_pattern_not(list);
 211                if (!x->u.unary)
 212                        die("--not followed by non pattern expression");
 213                return x;
 214        default:
 215                return compile_pattern_atom(list);
 216        }
 217}
 218
 219static struct grep_expr *compile_pattern_and(struct grep_pat **list)
 220{
 221        struct grep_pat *p;
 222        struct grep_expr *x, *y, *z;
 223
 224        x = compile_pattern_not(list);
 225        p = *list;
 226        if (p && p->token == GREP_AND) {
 227                if (!p->next)
 228                        die("--and not followed by pattern expression");
 229                *list = p->next;
 230                y = compile_pattern_and(list);
 231                if (!y)
 232                        die("--and not followed by pattern expression");
 233                z = xcalloc(1, sizeof (struct grep_expr));
 234                z->node = GREP_NODE_AND;
 235                z->u.binary.left = x;
 236                z->u.binary.right = y;
 237                return z;
 238        }
 239        return x;
 240}
 241
 242static struct grep_expr *compile_pattern_or(struct grep_pat **list)
 243{
 244        struct grep_pat *p;
 245        struct grep_expr *x, *y, *z;
 246
 247        x = compile_pattern_and(list);
 248        p = *list;
 249        if (x && p && p->token != GREP_CLOSE_PAREN) {
 250                y = compile_pattern_or(list);
 251                if (!y)
 252                        die("not a pattern expression %s", p->pattern);
 253                z = xcalloc(1, sizeof (struct grep_expr));
 254                z->node = GREP_NODE_OR;
 255                z->u.binary.left = x;
 256                z->u.binary.right = y;
 257                return z;
 258        }
 259        return x;
 260}
 261
 262static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
 263{
 264        return compile_pattern_or(list);
 265}
 266
 267static struct grep_expr *grep_true_expr(void)
 268{
 269        struct grep_expr *z = xcalloc(1, sizeof(*z));
 270        z->node = GREP_NODE_TRUE;
 271        return z;
 272}
 273
 274static struct grep_expr *grep_or_expr(struct grep_expr *left, struct grep_expr *right)
 275{
 276        struct grep_expr *z = xcalloc(1, sizeof(*z));
 277        z->node = GREP_NODE_OR;
 278        z->u.binary.left = left;
 279        z->u.binary.right = right;
 280        return z;
 281}
 282
 283static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
 284{
 285        struct grep_pat *p;
 286        struct grep_expr *header_expr;
 287        struct grep_expr *(header_group[GREP_HEADER_FIELD_MAX]);
 288        enum grep_header_field fld;
 289
 290        if (!opt->header_list)
 291                return NULL;
 292        p = opt->header_list;
 293        for (p = opt->header_list; p; p = p->next) {
 294                if (p->token != GREP_PATTERN_HEAD)
 295                        die("bug: a non-header pattern in grep header list.");
 296                if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
 297                        die("bug: unknown header field %d", p->field);
 298                compile_regexp(p, opt);
 299        }
 300
 301        for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++)
 302                header_group[fld] = NULL;
 303
 304        for (p = opt->header_list; p; p = p->next) {
 305                struct grep_expr *h;
 306                struct grep_pat *pp = p;
 307
 308                h = compile_pattern_atom(&pp);
 309                if (!h || pp != p->next)
 310                        die("bug: malformed header expr");
 311                if (!header_group[p->field]) {
 312                        header_group[p->field] = h;
 313                        continue;
 314                }
 315                header_group[p->field] = grep_or_expr(h, header_group[p->field]);
 316        }
 317
 318        header_expr = NULL;
 319
 320        for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++) {
 321                if (!header_group[fld])
 322                        continue;
 323                if (!header_expr)
 324                        header_expr = grep_true_expr();
 325                header_expr = grep_or_expr(header_group[fld], header_expr);
 326        }
 327        return header_expr;
 328}
 329
 330void compile_grep_patterns(struct grep_opt *opt)
 331{
 332        struct grep_pat *p;
 333        struct grep_expr *header_expr = prep_header_patterns(opt);
 334
 335        for (p = opt->pattern_list; p; p = p->next) {
 336                switch (p->token) {
 337                case GREP_PATTERN: /* atom */
 338                case GREP_PATTERN_HEAD:
 339                case GREP_PATTERN_BODY:
 340                        compile_regexp(p, opt);
 341                        break;
 342                default:
 343                        opt->extended = 1;
 344                        break;
 345                }
 346        }
 347
 348        if (opt->all_match || header_expr)
 349                opt->extended = 1;
 350        else if (!opt->extended)
 351                return;
 352
 353        p = opt->pattern_list;
 354        if (p)
 355                opt->pattern_expression = compile_pattern_expr(&p);
 356        if (p)
 357                die("incomplete pattern expression: %s", p->pattern);
 358
 359        if (!header_expr)
 360                return;
 361
 362        if (!opt->pattern_expression)
 363                opt->pattern_expression = header_expr;
 364        else
 365                opt->pattern_expression = grep_or_expr(opt->pattern_expression,
 366                                                       header_expr);
 367        opt->all_match = 1;
 368}
 369
 370static void free_pattern_expr(struct grep_expr *x)
 371{
 372        switch (x->node) {
 373        case GREP_NODE_TRUE:
 374        case GREP_NODE_ATOM:
 375                break;
 376        case GREP_NODE_NOT:
 377                free_pattern_expr(x->u.unary);
 378                break;
 379        case GREP_NODE_AND:
 380        case GREP_NODE_OR:
 381                free_pattern_expr(x->u.binary.left);
 382                free_pattern_expr(x->u.binary.right);
 383                break;
 384        }
 385        free(x);
 386}
 387
 388void free_grep_patterns(struct grep_opt *opt)
 389{
 390        struct grep_pat *p, *n;
 391
 392        for (p = opt->pattern_list; p; p = n) {
 393                n = p->next;
 394                switch (p->token) {
 395                case GREP_PATTERN: /* atom */
 396                case GREP_PATTERN_HEAD:
 397                case GREP_PATTERN_BODY:
 398                        if (p->pcre_regexp)
 399                                free_pcre_regexp(p);
 400                        else
 401                                regfree(&p->regexp);
 402                        break;
 403                default:
 404                        break;
 405                }
 406                free(p);
 407        }
 408
 409        if (!opt->extended)
 410                return;
 411        free_pattern_expr(opt->pattern_expression);
 412}
 413
 414static char *end_of_line(char *cp, unsigned long *left)
 415{
 416        unsigned long l = *left;
 417        while (l && *cp != '\n') {
 418                l--;
 419                cp++;
 420        }
 421        *left = l;
 422        return cp;
 423}
 424
 425static int word_char(char ch)
 426{
 427        return isalnum(ch) || ch == '_';
 428}
 429
 430static void output_color(struct grep_opt *opt, const void *data, size_t size,
 431                         const char *color)
 432{
 433        if (opt->color && color && color[0]) {
 434                opt->output(opt, color, strlen(color));
 435                opt->output(opt, data, size);
 436                opt->output(opt, GIT_COLOR_RESET, strlen(GIT_COLOR_RESET));
 437        } else
 438                opt->output(opt, data, size);
 439}
 440
 441static void output_sep(struct grep_opt *opt, char sign)
 442{
 443        if (opt->null_following_name)
 444                opt->output(opt, "\0", 1);
 445        else
 446                output_color(opt, &sign, 1, opt->color_sep);
 447}
 448
 449static void show_name(struct grep_opt *opt, const char *name)
 450{
 451        output_color(opt, name, strlen(name), opt->color_filename);
 452        opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 453}
 454
 455static int fixmatch(struct grep_pat *p, char *line, char *eol,
 456                    regmatch_t *match)
 457{
 458        char *hit;
 459
 460        if (p->ignore_case) {
 461                char *s = line;
 462                do {
 463                        hit = strcasestr(s, p->pattern);
 464                        if (hit)
 465                                break;
 466                        s += strlen(s) + 1;
 467                } while (s < eol);
 468        } else
 469                hit = memmem(line, eol - line, p->pattern, p->patternlen);
 470
 471        if (!hit) {
 472                match->rm_so = match->rm_eo = -1;
 473                return REG_NOMATCH;
 474        }
 475        else {
 476                match->rm_so = hit - line;
 477                match->rm_eo = match->rm_so + p->patternlen;
 478                return 0;
 479        }
 480}
 481
 482static int regmatch(const regex_t *preg, char *line, char *eol,
 483                    regmatch_t *match, int eflags)
 484{
 485#ifdef REG_STARTEND
 486        match->rm_so = 0;
 487        match->rm_eo = eol - line;
 488        eflags |= REG_STARTEND;
 489#endif
 490        return regexec(preg, line, 1, match, eflags);
 491}
 492
 493static int patmatch(struct grep_pat *p, char *line, char *eol,
 494                    regmatch_t *match, int eflags)
 495{
 496        int hit;
 497
 498        if (p->fixed)
 499                hit = !fixmatch(p, line, eol, match);
 500        else if (p->pcre_regexp)
 501                hit = !pcrematch(p, line, eol, match, eflags);
 502        else
 503                hit = !regmatch(&p->regexp, line, eol, match, eflags);
 504
 505        return hit;
 506}
 507
 508static int strip_timestamp(char *bol, char **eol_p)
 509{
 510        char *eol = *eol_p;
 511        int ch;
 512
 513        while (bol < --eol) {
 514                if (*eol != '>')
 515                        continue;
 516                *eol_p = ++eol;
 517                ch = *eol;
 518                *eol = '\0';
 519                return ch;
 520        }
 521        return 0;
 522}
 523
 524static struct {
 525        const char *field;
 526        size_t len;
 527} header_field[] = {
 528        { "author ", 7 },
 529        { "committer ", 10 },
 530};
 531
 532static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 533                             enum grep_context ctx,
 534                             regmatch_t *pmatch, int eflags)
 535{
 536        int hit = 0;
 537        int saved_ch = 0;
 538        const char *start = bol;
 539
 540        if ((p->token != GREP_PATTERN) &&
 541            ((p->token == GREP_PATTERN_HEAD) != (ctx == GREP_CONTEXT_HEAD)))
 542                return 0;
 543
 544        if (p->token == GREP_PATTERN_HEAD) {
 545                const char *field;
 546                size_t len;
 547                assert(p->field < ARRAY_SIZE(header_field));
 548                field = header_field[p->field].field;
 549                len = header_field[p->field].len;
 550                if (strncmp(bol, field, len))
 551                        return 0;
 552                bol += len;
 553                saved_ch = strip_timestamp(bol, &eol);
 554        }
 555
 556 again:
 557        hit = patmatch(p, bol, eol, pmatch, eflags);
 558
 559        if (hit && p->word_regexp) {
 560                if ((pmatch[0].rm_so < 0) ||
 561                    (eol - bol) < pmatch[0].rm_so ||
 562                    (pmatch[0].rm_eo < 0) ||
 563                    (eol - bol) < pmatch[0].rm_eo)
 564                        die("regexp returned nonsense");
 565
 566                /* Match beginning must be either beginning of the
 567                 * line, or at word boundary (i.e. the last char must
 568                 * not be a word char).  Similarly, match end must be
 569                 * either end of the line, or at word boundary
 570                 * (i.e. the next char must not be a word char).
 571                 */
 572                if ( ((pmatch[0].rm_so == 0) ||
 573                      !word_char(bol[pmatch[0].rm_so-1])) &&
 574                     ((pmatch[0].rm_eo == (eol-bol)) ||
 575                      !word_char(bol[pmatch[0].rm_eo])) )
 576                        ;
 577                else
 578                        hit = 0;
 579
 580                /* Words consist of at least one character. */
 581                if (pmatch->rm_so == pmatch->rm_eo)
 582                        hit = 0;
 583
 584                if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
 585                        /* There could be more than one match on the
 586                         * line, and the first match might not be
 587                         * strict word match.  But later ones could be!
 588                         * Forward to the next possible start, i.e. the
 589                         * next position following a non-word char.
 590                         */
 591                        bol = pmatch[0].rm_so + bol + 1;
 592                        while (word_char(bol[-1]) && bol < eol)
 593                                bol++;
 594                        eflags |= REG_NOTBOL;
 595                        if (bol < eol)
 596                                goto again;
 597                }
 598        }
 599        if (p->token == GREP_PATTERN_HEAD && saved_ch)
 600                *eol = saved_ch;
 601        if (hit) {
 602                pmatch[0].rm_so += bol - start;
 603                pmatch[0].rm_eo += bol - start;
 604        }
 605        return hit;
 606}
 607
 608static int match_expr_eval(struct grep_expr *x, char *bol, char *eol,
 609                           enum grep_context ctx, int collect_hits)
 610{
 611        int h = 0;
 612        regmatch_t match;
 613
 614        if (!x)
 615                die("Not a valid grep expression");
 616        switch (x->node) {
 617        case GREP_NODE_TRUE:
 618                h = 1;
 619                break;
 620        case GREP_NODE_ATOM:
 621                h = match_one_pattern(x->u.atom, bol, eol, ctx, &match, 0);
 622                break;
 623        case GREP_NODE_NOT:
 624                h = !match_expr_eval(x->u.unary, bol, eol, ctx, 0);
 625                break;
 626        case GREP_NODE_AND:
 627                if (!match_expr_eval(x->u.binary.left, bol, eol, ctx, 0))
 628                        return 0;
 629                h = match_expr_eval(x->u.binary.right, bol, eol, ctx, 0);
 630                break;
 631        case GREP_NODE_OR:
 632                if (!collect_hits)
 633                        return (match_expr_eval(x->u.binary.left,
 634                                                bol, eol, ctx, 0) ||
 635                                match_expr_eval(x->u.binary.right,
 636                                                bol, eol, ctx, 0));
 637                h = match_expr_eval(x->u.binary.left, bol, eol, ctx, 0);
 638                x->u.binary.left->hit |= h;
 639                h |= match_expr_eval(x->u.binary.right, bol, eol, ctx, 1);
 640                break;
 641        default:
 642                die("Unexpected node type (internal error) %d", x->node);
 643        }
 644        if (collect_hits)
 645                x->hit |= h;
 646        return h;
 647}
 648
 649static int match_expr(struct grep_opt *opt, char *bol, char *eol,
 650                      enum grep_context ctx, int collect_hits)
 651{
 652        struct grep_expr *x = opt->pattern_expression;
 653        return match_expr_eval(x, bol, eol, ctx, collect_hits);
 654}
 655
 656static int match_line(struct grep_opt *opt, char *bol, char *eol,
 657                      enum grep_context ctx, int collect_hits)
 658{
 659        struct grep_pat *p;
 660        regmatch_t match;
 661
 662        if (opt->extended)
 663                return match_expr(opt, bol, eol, ctx, collect_hits);
 664
 665        /* we do not call with collect_hits without being extended */
 666        for (p = opt->pattern_list; p; p = p->next) {
 667                if (match_one_pattern(p, bol, eol, ctx, &match, 0))
 668                        return 1;
 669        }
 670        return 0;
 671}
 672
 673static int match_next_pattern(struct grep_pat *p, char *bol, char *eol,
 674                              enum grep_context ctx,
 675                              regmatch_t *pmatch, int eflags)
 676{
 677        regmatch_t match;
 678
 679        if (!match_one_pattern(p, bol, eol, ctx, &match, eflags))
 680                return 0;
 681        if (match.rm_so < 0 || match.rm_eo < 0)
 682                return 0;
 683        if (pmatch->rm_so >= 0 && pmatch->rm_eo >= 0) {
 684                if (match.rm_so > pmatch->rm_so)
 685                        return 1;
 686                if (match.rm_so == pmatch->rm_so && match.rm_eo < pmatch->rm_eo)
 687                        return 1;
 688        }
 689        pmatch->rm_so = match.rm_so;
 690        pmatch->rm_eo = match.rm_eo;
 691        return 1;
 692}
 693
 694static int next_match(struct grep_opt *opt, char *bol, char *eol,
 695                      enum grep_context ctx, regmatch_t *pmatch, int eflags)
 696{
 697        struct grep_pat *p;
 698        int hit = 0;
 699
 700        pmatch->rm_so = pmatch->rm_eo = -1;
 701        if (bol < eol) {
 702                for (p = opt->pattern_list; p; p = p->next) {
 703                        switch (p->token) {
 704                        case GREP_PATTERN: /* atom */
 705                        case GREP_PATTERN_HEAD:
 706                        case GREP_PATTERN_BODY:
 707                                hit |= match_next_pattern(p, bol, eol, ctx,
 708                                                          pmatch, eflags);
 709                                break;
 710                        default:
 711                                break;
 712                        }
 713                }
 714        }
 715        return hit;
 716}
 717
 718static void show_line(struct grep_opt *opt, char *bol, char *eol,
 719                      const char *name, unsigned lno, char sign)
 720{
 721        int rest = eol - bol;
 722        char *line_color = NULL;
 723
 724        if (opt->pre_context || opt->post_context) {
 725                if (opt->last_shown == 0) {
 726                        if (opt->show_hunk_mark) {
 727                                output_color(opt, "--", 2, opt->color_sep);
 728                                opt->output(opt, "\n", 1);
 729                        }
 730                } else if (lno > opt->last_shown + 1) {
 731                        output_color(opt, "--", 2, opt->color_sep);
 732                        opt->output(opt, "\n", 1);
 733                }
 734        }
 735        opt->last_shown = lno;
 736
 737        if (opt->pathname) {
 738                output_color(opt, name, strlen(name), opt->color_filename);
 739                output_sep(opt, sign);
 740        }
 741        if (opt->linenum) {
 742                char buf[32];
 743                snprintf(buf, sizeof(buf), "%d", lno);
 744                output_color(opt, buf, strlen(buf), opt->color_lineno);
 745                output_sep(opt, sign);
 746        }
 747        if (opt->color) {
 748                regmatch_t match;
 749                enum grep_context ctx = GREP_CONTEXT_BODY;
 750                int ch = *eol;
 751                int eflags = 0;
 752
 753                if (sign == ':')
 754                        line_color = opt->color_selected;
 755                else if (sign == '-')
 756                        line_color = opt->color_context;
 757                else if (sign == '=')
 758                        line_color = opt->color_function;
 759                *eol = '\0';
 760                while (next_match(opt, bol, eol, ctx, &match, eflags)) {
 761                        if (match.rm_so == match.rm_eo)
 762                                break;
 763
 764                        output_color(opt, bol, match.rm_so, line_color);
 765                        output_color(opt, bol + match.rm_so,
 766                                     match.rm_eo - match.rm_so,
 767                                     opt->color_match);
 768                        bol += match.rm_eo;
 769                        rest -= match.rm_eo;
 770                        eflags = REG_NOTBOL;
 771                }
 772                *eol = ch;
 773        }
 774        output_color(opt, bol, rest, line_color);
 775        opt->output(opt, "\n", 1);
 776}
 777
 778static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
 779{
 780        xdemitconf_t *xecfg = opt->priv;
 781        if (xecfg && xecfg->find_func) {
 782                char buf[1];
 783                return xecfg->find_func(bol, eol - bol, buf, 1,
 784                                        xecfg->find_func_priv) >= 0;
 785        }
 786
 787        if (bol == eol)
 788                return 0;
 789        if (isalpha(*bol) || *bol == '_' || *bol == '$')
 790                return 1;
 791        return 0;
 792}
 793
 794static void show_funcname_line(struct grep_opt *opt, const char *name,
 795                               char *buf, char *bol, unsigned lno)
 796{
 797        while (bol > buf) {
 798                char *eol = --bol;
 799
 800                while (bol > buf && bol[-1] != '\n')
 801                        bol--;
 802                lno--;
 803
 804                if (lno <= opt->last_shown)
 805                        break;
 806
 807                if (match_funcname(opt, bol, eol)) {
 808                        show_line(opt, bol, eol, name, lno, '=');
 809                        break;
 810                }
 811        }
 812}
 813
 814static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
 815                             char *bol, unsigned lno)
 816{
 817        unsigned cur = lno, from = 1, funcname_lno = 0;
 818        int funcname_needed = opt->funcname;
 819
 820        if (opt->pre_context < lno)
 821                from = lno - opt->pre_context;
 822        if (from <= opt->last_shown)
 823                from = opt->last_shown + 1;
 824
 825        /* Rewind. */
 826        while (bol > buf && cur > from) {
 827                char *eol = --bol;
 828
 829                while (bol > buf && bol[-1] != '\n')
 830                        bol--;
 831                cur--;
 832                if (funcname_needed && match_funcname(opt, bol, eol)) {
 833                        funcname_lno = cur;
 834                        funcname_needed = 0;
 835                }
 836        }
 837
 838        /* We need to look even further back to find a function signature. */
 839        if (opt->funcname && funcname_needed)
 840                show_funcname_line(opt, name, buf, bol, cur);
 841
 842        /* Back forward. */
 843        while (cur < lno) {
 844                char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';
 845
 846                while (*eol != '\n')
 847                        eol++;
 848                show_line(opt, bol, eol, name, cur, sign);
 849                bol = eol + 1;
 850                cur++;
 851        }
 852}
 853
 854static int should_lookahead(struct grep_opt *opt)
 855{
 856        struct grep_pat *p;
 857
 858        if (opt->extended)
 859                return 0; /* punt for too complex stuff */
 860        if (opt->invert)
 861                return 0;
 862        for (p = opt->pattern_list; p; p = p->next) {
 863                if (p->token != GREP_PATTERN)
 864                        return 0; /* punt for "header only" and stuff */
 865        }
 866        return 1;
 867}
 868
 869static int look_ahead(struct grep_opt *opt,
 870                      unsigned long *left_p,
 871                      unsigned *lno_p,
 872                      char **bol_p)
 873{
 874        unsigned lno = *lno_p;
 875        char *bol = *bol_p;
 876        struct grep_pat *p;
 877        char *sp, *last_bol;
 878        regoff_t earliest = -1;
 879
 880        for (p = opt->pattern_list; p; p = p->next) {
 881                int hit;
 882                regmatch_t m;
 883
 884                hit = patmatch(p, bol, bol + *left_p, &m, 0);
 885                if (!hit || m.rm_so < 0 || m.rm_eo < 0)
 886                        continue;
 887                if (earliest < 0 || m.rm_so < earliest)
 888                        earliest = m.rm_so;
 889        }
 890
 891        if (earliest < 0) {
 892                *bol_p = bol + *left_p;
 893                *left_p = 0;
 894                return 1;
 895        }
 896        for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
 897                ; /* find the beginning of the line */
 898        last_bol = sp;
 899
 900        for (sp = bol; sp < last_bol; sp++) {
 901                if (*sp == '\n')
 902                        lno++;
 903        }
 904        *left_p -= last_bol - bol;
 905        *bol_p = last_bol;
 906        *lno_p = lno;
 907        return 0;
 908}
 909
 910int grep_threads_ok(const struct grep_opt *opt)
 911{
 912        /* If this condition is true, then we may use the attribute
 913         * machinery in grep_buffer_1. The attribute code is not
 914         * thread safe, so we disable the use of threads.
 915         */
 916        if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 917            !opt->name_only)
 918                return 0;
 919
 920        return 1;
 921}
 922
 923static void std_output(struct grep_opt *opt, const void *buf, size_t size)
 924{
 925        fwrite(buf, size, 1, stdout);
 926}
 927
 928static int grep_buffer_1(struct grep_opt *opt, const char *name,
 929                         char *buf, unsigned long size, int collect_hits)
 930{
 931        char *bol = buf;
 932        unsigned long left = size;
 933        unsigned lno = 1;
 934        unsigned last_hit = 0;
 935        int binary_match_only = 0;
 936        unsigned count = 0;
 937        int try_lookahead = 0;
 938        enum grep_context ctx = GREP_CONTEXT_HEAD;
 939        xdemitconf_t xecfg;
 940
 941        if (!opt->output)
 942                opt->output = std_output;
 943
 944        if (opt->last_shown && (opt->pre_context || opt->post_context) &&
 945            opt->output == std_output)
 946                opt->show_hunk_mark = 1;
 947        opt->last_shown = 0;
 948
 949        switch (opt->binary) {
 950        case GREP_BINARY_DEFAULT:
 951                if (buffer_is_binary(buf, size))
 952                        binary_match_only = 1;
 953                break;
 954        case GREP_BINARY_NOMATCH:
 955                if (buffer_is_binary(buf, size))
 956                        return 0; /* Assume unmatch */
 957                break;
 958        case GREP_BINARY_TEXT:
 959                break;
 960        default:
 961                die("bug: unknown binary handling mode");
 962        }
 963
 964        memset(&xecfg, 0, sizeof(xecfg));
 965        if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 966            !opt->name_only && !binary_match_only && !collect_hits) {
 967                struct userdiff_driver *drv = userdiff_find_by_path(name);
 968                if (drv && drv->funcname.pattern) {
 969                        const struct userdiff_funcname *pe = &drv->funcname;
 970                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
 971                        opt->priv = &xecfg;
 972                }
 973        }
 974        try_lookahead = should_lookahead(opt);
 975
 976        while (left) {
 977                char *eol, ch;
 978                int hit;
 979
 980                /*
 981                 * look_ahead() skips quickly to the line that possibly
 982                 * has the next hit; don't call it if we need to do
 983                 * something more than just skipping the current line
 984                 * in response to an unmatch for the current line.  E.g.
 985                 * inside a post-context window, we will show the current
 986                 * line as a context around the previous hit when it
 987                 * doesn't hit.
 988                 */
 989                if (try_lookahead
 990                    && !(last_hit
 991                         && lno <= last_hit + opt->post_context)
 992                    && look_ahead(opt, &left, &lno, &bol))
 993                        break;
 994                eol = end_of_line(bol, &left);
 995                ch = *eol;
 996                *eol = 0;
 997
 998                if ((ctx == GREP_CONTEXT_HEAD) && (eol == bol))
 999                        ctx = GREP_CONTEXT_BODY;
1000
1001                hit = match_line(opt, bol, eol, ctx, collect_hits);
1002                *eol = ch;
1003
1004                if (collect_hits)
1005                        goto next_line;
1006
1007                /* "grep -v -e foo -e bla" should list lines
1008                 * that do not have either, so inversion should
1009                 * be done outside.
1010                 */
1011                if (opt->invert)
1012                        hit = !hit;
1013                if (opt->unmatch_name_only) {
1014                        if (hit)
1015                                return 0;
1016                        goto next_line;
1017                }
1018                if (hit) {
1019                        count++;
1020                        if (opt->status_only)
1021                                return 1;
1022                        if (opt->name_only) {
1023                                show_name(opt, name);
1024                                return 1;
1025                        }
1026                        if (opt->count)
1027                                goto next_line;
1028                        if (binary_match_only) {
1029                                opt->output(opt, "Binary file ", 12);
1030                                output_color(opt, name, strlen(name),
1031                                             opt->color_filename);
1032                                opt->output(opt, " matches\n", 9);
1033                                return 1;
1034                        }
1035                        /* Hit at this line.  If we haven't shown the
1036                         * pre-context lines, we would need to show them.
1037                         */
1038                        if (opt->pre_context)
1039                                show_pre_context(opt, name, buf, bol, lno);
1040                        else if (opt->funcname)
1041                                show_funcname_line(opt, name, buf, bol, lno);
1042                        show_line(opt, bol, eol, name, lno, ':');
1043                        last_hit = lno;
1044                }
1045                else if (last_hit &&
1046                         lno <= last_hit + opt->post_context) {
1047                        /* If the last hit is within the post context,
1048                         * we need to show this line.
1049                         */
1050                        show_line(opt, bol, eol, name, lno, '-');
1051                }
1052
1053        next_line:
1054                bol = eol + 1;
1055                if (!left)
1056                        break;
1057                left--;
1058                lno++;
1059        }
1060
1061        if (collect_hits)
1062                return 0;
1063
1064        if (opt->status_only)
1065                return 0;
1066        if (opt->unmatch_name_only) {
1067                /* We did not see any hit, so we want to show this */
1068                show_name(opt, name);
1069                return 1;
1070        }
1071
1072        xdiff_clear_find_func(&xecfg);
1073        opt->priv = NULL;
1074
1075        /* NEEDSWORK:
1076         * The real "grep -c foo *.c" gives many "bar.c:0" lines,
1077         * which feels mostly useless but sometimes useful.  Maybe
1078         * make it another option?  For now suppress them.
1079         */
1080        if (opt->count && count) {
1081                char buf[32];
1082                output_color(opt, name, strlen(name), opt->color_filename);
1083                output_sep(opt, ':');
1084                snprintf(buf, sizeof(buf), "%u\n", count);
1085                opt->output(opt, buf, strlen(buf));
1086                return 1;
1087        }
1088        return !!last_hit;
1089}
1090
1091static void clr_hit_marker(struct grep_expr *x)
1092{
1093        /* All-hit markers are meaningful only at the very top level
1094         * OR node.
1095         */
1096        while (1) {
1097                x->hit = 0;
1098                if (x->node != GREP_NODE_OR)
1099                        return;
1100                x->u.binary.left->hit = 0;
1101                x = x->u.binary.right;
1102        }
1103}
1104
1105static int chk_hit_marker(struct grep_expr *x)
1106{
1107        /* Top level nodes have hit markers.  See if they all are hits */
1108        while (1) {
1109                if (x->node != GREP_NODE_OR)
1110                        return x->hit;
1111                if (!x->u.binary.left->hit)
1112                        return 0;
1113                x = x->u.binary.right;
1114        }
1115}
1116
1117int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsigned long size)
1118{
1119        /*
1120         * we do not have to do the two-pass grep when we do not check
1121         * buffer-wide "all-match".
1122         */
1123        if (!opt->all_match)
1124                return grep_buffer_1(opt, name, buf, size, 0);
1125
1126        /* Otherwise the toplevel "or" terms hit a bit differently.
1127         * We first clear hit markers from them.
1128         */
1129        clr_hit_marker(opt->pattern_expression);
1130        grep_buffer_1(opt, name, buf, size, 1);
1131
1132        if (!chk_hit_marker(opt->pattern_expression))
1133                return 0;
1134
1135        return grep_buffer_1(opt, name, buf, size, 0);
1136}