Andrew's git / gitweb.git / grep.c
?
grep.con commit Merge branch 'jc/maint-add-p-overlapping-hunks' into maint (c69e8b6)
   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 void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
  63{
  64        int err;
  65
  66        p->word_regexp = opt->word_regexp;
  67        p->ignore_case = opt->ignore_case;
  68        p->fixed = opt->fixed;
  69
  70        if (p->fixed)
  71                return;
  72
  73        err = regcomp(&p->regexp, p->pattern, opt->regflags);
  74        if (err) {
  75                char errbuf[1024];
  76                char where[1024];
  77                if (p->no)
  78                        sprintf(where, "In '%s' at %d, ",
  79                                p->origin, p->no);
  80                else if (p->origin)
  81                        sprintf(where, "%s, ", p->origin);
  82                else
  83                        where[0] = 0;
  84                regerror(err, &p->regexp, errbuf, 1024);
  85                regfree(&p->regexp);
  86                die("%s'%s': %s", where, p->pattern, errbuf);
  87        }
  88}
  89
  90static struct grep_expr *compile_pattern_or(struct grep_pat **);
  91static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
  92{
  93        struct grep_pat *p;
  94        struct grep_expr *x;
  95
  96        p = *list;
  97        if (!p)
  98                return NULL;
  99        switch (p->token) {
 100        case GREP_PATTERN: /* atom */
 101        case GREP_PATTERN_HEAD:
 102        case GREP_PATTERN_BODY:
 103                x = xcalloc(1, sizeof (struct grep_expr));
 104                x->node = GREP_NODE_ATOM;
 105                x->u.atom = p;
 106                *list = p->next;
 107                return x;
 108        case GREP_OPEN_PAREN:
 109                *list = p->next;
 110                x = compile_pattern_or(list);
 111                if (!*list || (*list)->token != GREP_CLOSE_PAREN)
 112                        die("unmatched parenthesis");
 113                *list = (*list)->next;
 114                return x;
 115        default:
 116                return NULL;
 117        }
 118}
 119
 120static struct grep_expr *compile_pattern_not(struct grep_pat **list)
 121{
 122        struct grep_pat *p;
 123        struct grep_expr *x;
 124
 125        p = *list;
 126        if (!p)
 127                return NULL;
 128        switch (p->token) {
 129        case GREP_NOT:
 130                if (!p->next)
 131                        die("--not not followed by pattern expression");
 132                *list = p->next;
 133                x = xcalloc(1, sizeof (struct grep_expr));
 134                x->node = GREP_NODE_NOT;
 135                x->u.unary = compile_pattern_not(list);
 136                if (!x->u.unary)
 137                        die("--not followed by non pattern expression");
 138                return x;
 139        default:
 140                return compile_pattern_atom(list);
 141        }
 142}
 143
 144static struct grep_expr *compile_pattern_and(struct grep_pat **list)
 145{
 146        struct grep_pat *p;
 147        struct grep_expr *x, *y, *z;
 148
 149        x = compile_pattern_not(list);
 150        p = *list;
 151        if (p && p->token == GREP_AND) {
 152                if (!p->next)
 153                        die("--and not followed by pattern expression");
 154                *list = p->next;
 155                y = compile_pattern_and(list);
 156                if (!y)
 157                        die("--and not followed by pattern expression");
 158                z = xcalloc(1, sizeof (struct grep_expr));
 159                z->node = GREP_NODE_AND;
 160                z->u.binary.left = x;
 161                z->u.binary.right = y;
 162                return z;
 163        }
 164        return x;
 165}
 166
 167static struct grep_expr *compile_pattern_or(struct grep_pat **list)
 168{
 169        struct grep_pat *p;
 170        struct grep_expr *x, *y, *z;
 171
 172        x = compile_pattern_and(list);
 173        p = *list;
 174        if (x && p && p->token != GREP_CLOSE_PAREN) {
 175                y = compile_pattern_or(list);
 176                if (!y)
 177                        die("not a pattern expression %s", p->pattern);
 178                z = xcalloc(1, sizeof (struct grep_expr));
 179                z->node = GREP_NODE_OR;
 180                z->u.binary.left = x;
 181                z->u.binary.right = y;
 182                return z;
 183        }
 184        return x;
 185}
 186
 187static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
 188{
 189        return compile_pattern_or(list);
 190}
 191
 192static struct grep_expr *grep_true_expr(void)
 193{
 194        struct grep_expr *z = xcalloc(1, sizeof(*z));
 195        z->node = GREP_NODE_TRUE;
 196        return z;
 197}
 198
 199static struct grep_expr *grep_or_expr(struct grep_expr *left, struct grep_expr *right)
 200{
 201        struct grep_expr *z = xcalloc(1, sizeof(*z));
 202        z->node = GREP_NODE_OR;
 203        z->u.binary.left = left;
 204        z->u.binary.right = right;
 205        return z;
 206}
 207
 208static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
 209{
 210        struct grep_pat *p;
 211        struct grep_expr *header_expr;
 212        struct grep_expr *(header_group[GREP_HEADER_FIELD_MAX]);
 213        enum grep_header_field fld;
 214
 215        if (!opt->header_list)
 216                return NULL;
 217        p = opt->header_list;
 218        for (p = opt->header_list; p; p = p->next) {
 219                if (p->token != GREP_PATTERN_HEAD)
 220                        die("bug: a non-header pattern in grep header list.");
 221                if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
 222                        die("bug: unknown header field %d", p->field);
 223                compile_regexp(p, opt);
 224        }
 225
 226        for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++)
 227                header_group[fld] = NULL;
 228
 229        for (p = opt->header_list; p; p = p->next) {
 230                struct grep_expr *h;
 231                struct grep_pat *pp = p;
 232
 233                h = compile_pattern_atom(&pp);
 234                if (!h || pp != p->next)
 235                        die("bug: malformed header expr");
 236                if (!header_group[p->field]) {
 237                        header_group[p->field] = h;
 238                        continue;
 239                }
 240                header_group[p->field] = grep_or_expr(h, header_group[p->field]);
 241        }
 242
 243        header_expr = NULL;
 244
 245        for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++) {
 246                if (!header_group[fld])
 247                        continue;
 248                if (!header_expr)
 249                        header_expr = grep_true_expr();
 250                header_expr = grep_or_expr(header_group[fld], header_expr);
 251        }
 252        return header_expr;
 253}
 254
 255void compile_grep_patterns(struct grep_opt *opt)
 256{
 257        struct grep_pat *p;
 258        struct grep_expr *header_expr = prep_header_patterns(opt);
 259
 260        for (p = opt->pattern_list; p; p = p->next) {
 261                switch (p->token) {
 262                case GREP_PATTERN: /* atom */
 263                case GREP_PATTERN_HEAD:
 264                case GREP_PATTERN_BODY:
 265                        compile_regexp(p, opt);
 266                        break;
 267                default:
 268                        opt->extended = 1;
 269                        break;
 270                }
 271        }
 272
 273        if (opt->all_match || header_expr)
 274                opt->extended = 1;
 275        else if (!opt->extended)
 276                return;
 277
 278        p = opt->pattern_list;
 279        if (p)
 280                opt->pattern_expression = compile_pattern_expr(&p);
 281        if (p)
 282                die("incomplete pattern expression: %s", p->pattern);
 283
 284        if (!header_expr)
 285                return;
 286
 287        if (!opt->pattern_expression)
 288                opt->pattern_expression = header_expr;
 289        else
 290                opt->pattern_expression = grep_or_expr(opt->pattern_expression,
 291                                                       header_expr);
 292        opt->all_match = 1;
 293}
 294
 295static void free_pattern_expr(struct grep_expr *x)
 296{
 297        switch (x->node) {
 298        case GREP_NODE_TRUE:
 299        case GREP_NODE_ATOM:
 300                break;
 301        case GREP_NODE_NOT:
 302                free_pattern_expr(x->u.unary);
 303                break;
 304        case GREP_NODE_AND:
 305        case GREP_NODE_OR:
 306                free_pattern_expr(x->u.binary.left);
 307                free_pattern_expr(x->u.binary.right);
 308                break;
 309        }
 310        free(x);
 311}
 312
 313void free_grep_patterns(struct grep_opt *opt)
 314{
 315        struct grep_pat *p, *n;
 316
 317        for (p = opt->pattern_list; p; p = n) {
 318                n = p->next;
 319                switch (p->token) {
 320                case GREP_PATTERN: /* atom */
 321                case GREP_PATTERN_HEAD:
 322                case GREP_PATTERN_BODY:
 323                        regfree(&p->regexp);
 324                        break;
 325                default:
 326                        break;
 327                }
 328                free(p);
 329        }
 330
 331        if (!opt->extended)
 332                return;
 333        free_pattern_expr(opt->pattern_expression);
 334}
 335
 336static char *end_of_line(char *cp, unsigned long *left)
 337{
 338        unsigned long l = *left;
 339        while (l && *cp != '\n') {
 340                l--;
 341                cp++;
 342        }
 343        *left = l;
 344        return cp;
 345}
 346
 347static int word_char(char ch)
 348{
 349        return isalnum(ch) || ch == '_';
 350}
 351
 352static void output_color(struct grep_opt *opt, const void *data, size_t size,
 353                         const char *color)
 354{
 355        if (opt->color && color && color[0]) {
 356                opt->output(opt, color, strlen(color));
 357                opt->output(opt, data, size);
 358                opt->output(opt, GIT_COLOR_RESET, strlen(GIT_COLOR_RESET));
 359        } else
 360                opt->output(opt, data, size);
 361}
 362
 363static void output_sep(struct grep_opt *opt, char sign)
 364{
 365        if (opt->null_following_name)
 366                opt->output(opt, "\0", 1);
 367        else
 368                output_color(opt, &sign, 1, opt->color_sep);
 369}
 370
 371static void show_name(struct grep_opt *opt, const char *name)
 372{
 373        output_color(opt, name, strlen(name), opt->color_filename);
 374        opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 375}
 376
 377static int fixmatch(struct grep_pat *p, char *line, char *eol,
 378                    regmatch_t *match)
 379{
 380        char *hit;
 381
 382        if (p->ignore_case) {
 383                char *s = line;
 384                do {
 385                        hit = strcasestr(s, p->pattern);
 386                        if (hit)
 387                                break;
 388                        s += strlen(s) + 1;
 389                } while (s < eol);
 390        } else
 391                hit = memmem(line, eol - line, p->pattern, p->patternlen);
 392
 393        if (!hit) {
 394                match->rm_so = match->rm_eo = -1;
 395                return REG_NOMATCH;
 396        }
 397        else {
 398                match->rm_so = hit - line;
 399                match->rm_eo = match->rm_so + p->patternlen;
 400                return 0;
 401        }
 402}
 403
 404static int regmatch(const regex_t *preg, char *line, char *eol,
 405                    regmatch_t *match, int eflags)
 406{
 407#ifdef REG_STARTEND
 408        match->rm_so = 0;
 409        match->rm_eo = eol - line;
 410        eflags |= REG_STARTEND;
 411#endif
 412        return regexec(preg, line, 1, match, eflags);
 413}
 414
 415static int strip_timestamp(char *bol, char **eol_p)
 416{
 417        char *eol = *eol_p;
 418        int ch;
 419
 420        while (bol < --eol) {
 421                if (*eol != '>')
 422                        continue;
 423                *eol_p = ++eol;
 424                ch = *eol;
 425                *eol = '\0';
 426                return ch;
 427        }
 428        return 0;
 429}
 430
 431static struct {
 432        const char *field;
 433        size_t len;
 434} header_field[] = {
 435        { "author ", 7 },
 436        { "committer ", 10 },
 437};
 438
 439static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 440                             enum grep_context ctx,
 441                             regmatch_t *pmatch, int eflags)
 442{
 443        int hit = 0;
 444        int saved_ch = 0;
 445        const char *start = bol;
 446
 447        if ((p->token != GREP_PATTERN) &&
 448            ((p->token == GREP_PATTERN_HEAD) != (ctx == GREP_CONTEXT_HEAD)))
 449                return 0;
 450
 451        if (p->token == GREP_PATTERN_HEAD) {
 452                const char *field;
 453                size_t len;
 454                assert(p->field < ARRAY_SIZE(header_field));
 455                field = header_field[p->field].field;
 456                len = header_field[p->field].len;
 457                if (strncmp(bol, field, len))
 458                        return 0;
 459                bol += len;
 460                saved_ch = strip_timestamp(bol, &eol);
 461        }
 462
 463 again:
 464        if (p->fixed)
 465                hit = !fixmatch(p, bol, eol, pmatch);
 466        else
 467                hit = !regmatch(&p->regexp, bol, eol, pmatch, eflags);
 468
 469        if (hit && p->word_regexp) {
 470                if ((pmatch[0].rm_so < 0) ||
 471                    (eol - bol) < pmatch[0].rm_so ||
 472                    (pmatch[0].rm_eo < 0) ||
 473                    (eol - bol) < pmatch[0].rm_eo)
 474                        die("regexp returned nonsense");
 475
 476                /* Match beginning must be either beginning of the
 477                 * line, or at word boundary (i.e. the last char must
 478                 * not be a word char).  Similarly, match end must be
 479                 * either end of the line, or at word boundary
 480                 * (i.e. the next char must not be a word char).
 481                 */
 482                if ( ((pmatch[0].rm_so == 0) ||
 483                      !word_char(bol[pmatch[0].rm_so-1])) &&
 484                     ((pmatch[0].rm_eo == (eol-bol)) ||
 485                      !word_char(bol[pmatch[0].rm_eo])) )
 486                        ;
 487                else
 488                        hit = 0;
 489
 490                /* Words consist of at least one character. */
 491                if (pmatch->rm_so == pmatch->rm_eo)
 492                        hit = 0;
 493
 494                if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
 495                        /* There could be more than one match on the
 496                         * line, and the first match might not be
 497                         * strict word match.  But later ones could be!
 498                         * Forward to the next possible start, i.e. the
 499                         * next position following a non-word char.
 500                         */
 501                        bol = pmatch[0].rm_so + bol + 1;
 502                        while (word_char(bol[-1]) && bol < eol)
 503                                bol++;
 504                        eflags |= REG_NOTBOL;
 505                        if (bol < eol)
 506                                goto again;
 507                }
 508        }
 509        if (p->token == GREP_PATTERN_HEAD && saved_ch)
 510                *eol = saved_ch;
 511        if (hit) {
 512                pmatch[0].rm_so += bol - start;
 513                pmatch[0].rm_eo += bol - start;
 514        }
 515        return hit;
 516}
 517
 518static int match_expr_eval(struct grep_expr *x, char *bol, char *eol,
 519                           enum grep_context ctx, int collect_hits)
 520{
 521        int h = 0;
 522        regmatch_t match;
 523
 524        if (!x)
 525                die("Not a valid grep expression");
 526        switch (x->node) {
 527        case GREP_NODE_TRUE:
 528                h = 1;
 529                break;
 530        case GREP_NODE_ATOM:
 531                h = match_one_pattern(x->u.atom, bol, eol, ctx, &match, 0);
 532                break;
 533        case GREP_NODE_NOT:
 534                h = !match_expr_eval(x->u.unary, bol, eol, ctx, 0);
 535                break;
 536        case GREP_NODE_AND:
 537                if (!match_expr_eval(x->u.binary.left, bol, eol, ctx, 0))
 538                        return 0;
 539                h = match_expr_eval(x->u.binary.right, bol, eol, ctx, 0);
 540                break;
 541        case GREP_NODE_OR:
 542                if (!collect_hits)
 543                        return (match_expr_eval(x->u.binary.left,
 544                                                bol, eol, ctx, 0) ||
 545                                match_expr_eval(x->u.binary.right,
 546                                                bol, eol, ctx, 0));
 547                h = match_expr_eval(x->u.binary.left, bol, eol, ctx, 0);
 548                x->u.binary.left->hit |= h;
 549                h |= match_expr_eval(x->u.binary.right, bol, eol, ctx, 1);
 550                break;
 551        default:
 552                die("Unexpected node type (internal error) %d", x->node);
 553        }
 554        if (collect_hits)
 555                x->hit |= h;
 556        return h;
 557}
 558
 559static int match_expr(struct grep_opt *opt, char *bol, char *eol,
 560                      enum grep_context ctx, int collect_hits)
 561{
 562        struct grep_expr *x = opt->pattern_expression;
 563        return match_expr_eval(x, bol, eol, ctx, collect_hits);
 564}
 565
 566static int match_line(struct grep_opt *opt, char *bol, char *eol,
 567                      enum grep_context ctx, int collect_hits)
 568{
 569        struct grep_pat *p;
 570        regmatch_t match;
 571
 572        if (opt->extended)
 573                return match_expr(opt, bol, eol, ctx, collect_hits);
 574
 575        /* we do not call with collect_hits without being extended */
 576        for (p = opt->pattern_list; p; p = p->next) {
 577                if (match_one_pattern(p, bol, eol, ctx, &match, 0))
 578                        return 1;
 579        }
 580        return 0;
 581}
 582
 583static int match_next_pattern(struct grep_pat *p, char *bol, char *eol,
 584                              enum grep_context ctx,
 585                              regmatch_t *pmatch, int eflags)
 586{
 587        regmatch_t match;
 588
 589        if (!match_one_pattern(p, bol, eol, ctx, &match, eflags))
 590                return 0;
 591        if (match.rm_so < 0 || match.rm_eo < 0)
 592                return 0;
 593        if (pmatch->rm_so >= 0 && pmatch->rm_eo >= 0) {
 594                if (match.rm_so > pmatch->rm_so)
 595                        return 1;
 596                if (match.rm_so == pmatch->rm_so && match.rm_eo < pmatch->rm_eo)
 597                        return 1;
 598        }
 599        pmatch->rm_so = match.rm_so;
 600        pmatch->rm_eo = match.rm_eo;
 601        return 1;
 602}
 603
 604static int next_match(struct grep_opt *opt, char *bol, char *eol,
 605                      enum grep_context ctx, regmatch_t *pmatch, int eflags)
 606{
 607        struct grep_pat *p;
 608        int hit = 0;
 609
 610        pmatch->rm_so = pmatch->rm_eo = -1;
 611        if (bol < eol) {
 612                for (p = opt->pattern_list; p; p = p->next) {
 613                        switch (p->token) {
 614                        case GREP_PATTERN: /* atom */
 615                        case GREP_PATTERN_HEAD:
 616                        case GREP_PATTERN_BODY:
 617                                hit |= match_next_pattern(p, bol, eol, ctx,
 618                                                          pmatch, eflags);
 619                                break;
 620                        default:
 621                                break;
 622                        }
 623                }
 624        }
 625        return hit;
 626}
 627
 628static void show_line(struct grep_opt *opt, char *bol, char *eol,
 629                      const char *name, unsigned lno, char sign)
 630{
 631        int rest = eol - bol;
 632        char *line_color = NULL;
 633
 634        if (opt->pre_context || opt->post_context) {
 635                if (opt->last_shown == 0) {
 636                        if (opt->show_hunk_mark) {
 637                                output_color(opt, "--", 2, opt->color_sep);
 638                                opt->output(opt, "\n", 1);
 639                        }
 640                } else if (lno > opt->last_shown + 1) {
 641                        output_color(opt, "--", 2, opt->color_sep);
 642                        opt->output(opt, "\n", 1);
 643                }
 644        }
 645        opt->last_shown = lno;
 646
 647        if (opt->pathname) {
 648                output_color(opt, name, strlen(name), opt->color_filename);
 649                output_sep(opt, sign);
 650        }
 651        if (opt->linenum) {
 652                char buf[32];
 653                snprintf(buf, sizeof(buf), "%d", lno);
 654                output_color(opt, buf, strlen(buf), opt->color_lineno);
 655                output_sep(opt, sign);
 656        }
 657        if (opt->color) {
 658                regmatch_t match;
 659                enum grep_context ctx = GREP_CONTEXT_BODY;
 660                int ch = *eol;
 661                int eflags = 0;
 662
 663                if (sign == ':')
 664                        line_color = opt->color_selected;
 665                else if (sign == '-')
 666                        line_color = opt->color_context;
 667                else if (sign == '=')
 668                        line_color = opt->color_function;
 669                *eol = '\0';
 670                while (next_match(opt, bol, eol, ctx, &match, eflags)) {
 671                        if (match.rm_so == match.rm_eo)
 672                                break;
 673
 674                        output_color(opt, bol, match.rm_so, line_color);
 675                        output_color(opt, bol + match.rm_so,
 676                                     match.rm_eo - match.rm_so,
 677                                     opt->color_match);
 678                        bol += match.rm_eo;
 679                        rest -= match.rm_eo;
 680                        eflags = REG_NOTBOL;
 681                }
 682                *eol = ch;
 683        }
 684        output_color(opt, bol, rest, line_color);
 685        opt->output(opt, "\n", 1);
 686}
 687
 688static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
 689{
 690        xdemitconf_t *xecfg = opt->priv;
 691        if (xecfg && xecfg->find_func) {
 692                char buf[1];
 693                return xecfg->find_func(bol, eol - bol, buf, 1,
 694                                        xecfg->find_func_priv) >= 0;
 695        }
 696
 697        if (bol == eol)
 698                return 0;
 699        if (isalpha(*bol) || *bol == '_' || *bol == '$')
 700                return 1;
 701        return 0;
 702}
 703
 704static void show_funcname_line(struct grep_opt *opt, const char *name,
 705                               char *buf, char *bol, unsigned lno)
 706{
 707        while (bol > buf) {
 708                char *eol = --bol;
 709
 710                while (bol > buf && bol[-1] != '\n')
 711                        bol--;
 712                lno--;
 713
 714                if (lno <= opt->last_shown)
 715                        break;
 716
 717                if (match_funcname(opt, bol, eol)) {
 718                        show_line(opt, bol, eol, name, lno, '=');
 719                        break;
 720                }
 721        }
 722}
 723
 724static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
 725                             char *bol, unsigned lno)
 726{
 727        unsigned cur = lno, from = 1, funcname_lno = 0;
 728        int funcname_needed = opt->funcname;
 729
 730        if (opt->pre_context < lno)
 731                from = lno - opt->pre_context;
 732        if (from <= opt->last_shown)
 733                from = opt->last_shown + 1;
 734
 735        /* Rewind. */
 736        while (bol > buf && cur > from) {
 737                char *eol = --bol;
 738
 739                while (bol > buf && bol[-1] != '\n')
 740                        bol--;
 741                cur--;
 742                if (funcname_needed && match_funcname(opt, bol, eol)) {
 743                        funcname_lno = cur;
 744                        funcname_needed = 0;
 745                }
 746        }
 747
 748        /* We need to look even further back to find a function signature. */
 749        if (opt->funcname && funcname_needed)
 750                show_funcname_line(opt, name, buf, bol, cur);
 751
 752        /* Back forward. */
 753        while (cur < lno) {
 754                char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';
 755
 756                while (*eol != '\n')
 757                        eol++;
 758                show_line(opt, bol, eol, name, cur, sign);
 759                bol = eol + 1;
 760                cur++;
 761        }
 762}
 763
 764static int should_lookahead(struct grep_opt *opt)
 765{
 766        struct grep_pat *p;
 767
 768        if (opt->extended)
 769                return 0; /* punt for too complex stuff */
 770        if (opt->invert)
 771                return 0;
 772        for (p = opt->pattern_list; p; p = p->next) {
 773                if (p->token != GREP_PATTERN)
 774                        return 0; /* punt for "header only" and stuff */
 775        }
 776        return 1;
 777}
 778
 779static int look_ahead(struct grep_opt *opt,
 780                      unsigned long *left_p,
 781                      unsigned *lno_p,
 782                      char **bol_p)
 783{
 784        unsigned lno = *lno_p;
 785        char *bol = *bol_p;
 786        struct grep_pat *p;
 787        char *sp, *last_bol;
 788        regoff_t earliest = -1;
 789
 790        for (p = opt->pattern_list; p; p = p->next) {
 791                int hit;
 792                regmatch_t m;
 793
 794                if (p->fixed)
 795                        hit = !fixmatch(p, bol, bol + *left_p, &m);
 796                else
 797                        hit = !regmatch(&p->regexp, bol, bol + *left_p, &m, 0);
 798                if (!hit || m.rm_so < 0 || m.rm_eo < 0)
 799                        continue;
 800                if (earliest < 0 || m.rm_so < earliest)
 801                        earliest = m.rm_so;
 802        }
 803
 804        if (earliest < 0) {
 805                *bol_p = bol + *left_p;
 806                *left_p = 0;
 807                return 1;
 808        }
 809        for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
 810                ; /* find the beginning of the line */
 811        last_bol = sp;
 812
 813        for (sp = bol; sp < last_bol; sp++) {
 814                if (*sp == '\n')
 815                        lno++;
 816        }
 817        *left_p -= last_bol - bol;
 818        *bol_p = last_bol;
 819        *lno_p = lno;
 820        return 0;
 821}
 822
 823int grep_threads_ok(const struct grep_opt *opt)
 824{
 825        /* If this condition is true, then we may use the attribute
 826         * machinery in grep_buffer_1. The attribute code is not
 827         * thread safe, so we disable the use of threads.
 828         */
 829        if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 830            !opt->name_only)
 831                return 0;
 832
 833        return 1;
 834}
 835
 836static void std_output(struct grep_opt *opt, const void *buf, size_t size)
 837{
 838        fwrite(buf, size, 1, stdout);
 839}
 840
 841static int grep_buffer_1(struct grep_opt *opt, const char *name,
 842                         char *buf, unsigned long size, int collect_hits)
 843{
 844        char *bol = buf;
 845        unsigned long left = size;
 846        unsigned lno = 1;
 847        unsigned last_hit = 0;
 848        int binary_match_only = 0;
 849        unsigned count = 0;
 850        int try_lookahead = 0;
 851        enum grep_context ctx = GREP_CONTEXT_HEAD;
 852        xdemitconf_t xecfg;
 853
 854        if (!opt->output)
 855                opt->output = std_output;
 856
 857        if (opt->last_shown && (opt->pre_context || opt->post_context) &&
 858            opt->output == std_output)
 859                opt->show_hunk_mark = 1;
 860        opt->last_shown = 0;
 861
 862        switch (opt->binary) {
 863        case GREP_BINARY_DEFAULT:
 864                if (buffer_is_binary(buf, size))
 865                        binary_match_only = 1;
 866                break;
 867        case GREP_BINARY_NOMATCH:
 868                if (buffer_is_binary(buf, size))
 869                        return 0; /* Assume unmatch */
 870                break;
 871        case GREP_BINARY_TEXT:
 872                break;
 873        default:
 874                die("bug: unknown binary handling mode");
 875        }
 876
 877        memset(&xecfg, 0, sizeof(xecfg));
 878        if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
 879            !opt->name_only && !binary_match_only && !collect_hits) {
 880                struct userdiff_driver *drv = userdiff_find_by_path(name);
 881                if (drv && drv->funcname.pattern) {
 882                        const struct userdiff_funcname *pe = &drv->funcname;
 883                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
 884                        opt->priv = &xecfg;
 885                }
 886        }
 887        try_lookahead = should_lookahead(opt);
 888
 889        while (left) {
 890                char *eol, ch;
 891                int hit;
 892
 893                /*
 894                 * look_ahead() skips quicly to the line that possibly
 895                 * has the next hit; don't call it if we need to do
 896                 * something more than just skipping the current line
 897                 * in response to an unmatch for the current line.  E.g.
 898                 * inside a post-context window, we will show the current
 899                 * line as a context around the previous hit when it
 900                 * doesn't hit.
 901                 */
 902                if (try_lookahead
 903                    && !(last_hit
 904                         && lno <= last_hit + opt->post_context)
 905                    && look_ahead(opt, &left, &lno, &bol))
 906                        break;
 907                eol = end_of_line(bol, &left);
 908                ch = *eol;
 909                *eol = 0;
 910
 911                if ((ctx == GREP_CONTEXT_HEAD) && (eol == bol))
 912                        ctx = GREP_CONTEXT_BODY;
 913
 914                hit = match_line(opt, bol, eol, ctx, collect_hits);
 915                *eol = ch;
 916
 917                if (collect_hits)
 918                        goto next_line;
 919
 920                /* "grep -v -e foo -e bla" should list lines
 921                 * that do not have either, so inversion should
 922                 * be done outside.
 923                 */
 924                if (opt->invert)
 925                        hit = !hit;
 926                if (opt->unmatch_name_only) {
 927                        if (hit)
 928                                return 0;
 929                        goto next_line;
 930                }
 931                if (hit) {
 932                        count++;
 933                        if (opt->status_only)
 934                                return 1;
 935                        if (opt->name_only) {
 936                                show_name(opt, name);
 937                                return 1;
 938                        }
 939                        if (opt->count)
 940                                goto next_line;
 941                        if (binary_match_only) {
 942                                opt->output(opt, "Binary file ", 12);
 943                                output_color(opt, name, strlen(name),
 944                                             opt->color_filename);
 945                                opt->output(opt, " matches\n", 9);
 946                                return 1;
 947                        }
 948                        /* Hit at this line.  If we haven't shown the
 949                         * pre-context lines, we would need to show them.
 950                         */
 951                        if (opt->pre_context)
 952                                show_pre_context(opt, name, buf, bol, lno);
 953                        else if (opt->funcname)
 954                                show_funcname_line(opt, name, buf, bol, lno);
 955                        show_line(opt, bol, eol, name, lno, ':');
 956                        last_hit = lno;
 957                }
 958                else if (last_hit &&
 959                         lno <= last_hit + opt->post_context) {
 960                        /* If the last hit is within the post context,
 961                         * we need to show this line.
 962                         */
 963                        show_line(opt, bol, eol, name, lno, '-');
 964                }
 965
 966        next_line:
 967                bol = eol + 1;
 968                if (!left)
 969                        break;
 970                left--;
 971                lno++;
 972        }
 973
 974        if (collect_hits)
 975                return 0;
 976
 977        if (opt->status_only)
 978                return 0;
 979        if (opt->unmatch_name_only) {
 980                /* We did not see any hit, so we want to show this */
 981                show_name(opt, name);
 982                return 1;
 983        }
 984
 985        xdiff_clear_find_func(&xecfg);
 986        opt->priv = NULL;
 987
 988        /* NEEDSWORK:
 989         * The real "grep -c foo *.c" gives many "bar.c:0" lines,
 990         * which feels mostly useless but sometimes useful.  Maybe
 991         * make it another option?  For now suppress them.
 992         */
 993        if (opt->count && count) {
 994                char buf[32];
 995                output_color(opt, name, strlen(name), opt->color_filename);
 996                output_sep(opt, ':');
 997                snprintf(buf, sizeof(buf), "%u\n", count);
 998                opt->output(opt, buf, strlen(buf));
 999                return 1;
1000        }
1001        return !!last_hit;
1002}
1003
1004static void clr_hit_marker(struct grep_expr *x)
1005{
1006        /* All-hit markers are meaningful only at the very top level
1007         * OR node.
1008         */
1009        while (1) {
1010                x->hit = 0;
1011                if (x->node != GREP_NODE_OR)
1012                        return;
1013                x->u.binary.left->hit = 0;
1014                x = x->u.binary.right;
1015        }
1016}
1017
1018static int chk_hit_marker(struct grep_expr *x)
1019{
1020        /* Top level nodes have hit markers.  See if they all are hits */
1021        while (1) {
1022                if (x->node != GREP_NODE_OR)
1023                        return x->hit;
1024                if (!x->u.binary.left->hit)
1025                        return 0;
1026                x = x->u.binary.right;
1027        }
1028}
1029
1030int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsigned long size)
1031{
1032        /*
1033         * we do not have to do the two-pass grep when we do not check
1034         * buffer-wide "all-match".
1035         */
1036        if (!opt->all_match)
1037                return grep_buffer_1(opt, name, buf, size, 0);
1038
1039        /* Otherwise the toplevel "or" terms hit a bit differently.
1040         * We first clear hit markers from them.
1041         */
1042        clr_hit_marker(opt->pattern_expression);
1043        grep_buffer_1(opt, name, buf, size, 1);
1044
1045        if (!chk_hit_marker(opt->pattern_expression))
1046                return 0;
1047
1048        return grep_buffer_1(opt, name, buf, size, 0);
1049}