about summary refs log blame commit diff
path: root/grep.c
blob: 13232a904aca4906f28aae2e04165d1fda47b922 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542

















                                                             













                                                                          





































































































































                                                                              




                                                                





                                                                                 










                                                                        





















                                                                      






                                                         





























































































































































































                                                                                                   





                                                                                
                              

                               
                                                                     


                                                            
                                                                                 






                                                                               
                                                         
                                                       




                                                                      
      



                                                                                 




                                                                            
                                                         



                                     


                                                                   














                                                                

                            
                                                     
            
      
                                               

























                                                                                     







                                        
                                                                        
                               



                                                                                 
                                                                                      

                                                                            


                                          

                                                                                   















                                                                                                   


                                                                      























                                                                                                   


                                                                                        

                               










































                                                                                
                                      




















                                                                                     



















                                                                          
                          


                                                                    




                                          
                              
 














































                                                                                                                         
                                             
                          













































































































































































































































































































































































                                                                                      
                                            


























































                                                                                




                                                              
                            










































































































































































































































































































































































































                                                                                        



































































































































































































                                                                                             









                                                                                
           
                        
                                                  
                          
































































                                                                                        



                                                                              

                                 
                                
                                                                        
                                  










































































































































































































































































































                                                                                
                                                                     


















































































                                                                        
#include "cache.h"
#include "config.h"
#include "grep.h"
#include "object-store.h"
#include "userdiff.h"
#include "xdiff-interface.h"
#include "diff.h"
#include "diffcore.h"
#include "commit.h"
#include "quote.h"
#include "help.h"

static int grep_source_load(struct grep_source *gs);
static int grep_source_is_binary(struct grep_source *gs,
				 struct index_state *istate);

static struct grep_opt grep_defaults;

#ifdef USE_LIBPCRE2
static pcre2_general_context *pcre2_global_context;

static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
{
	return malloc(size);
}

static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
{
	free(pointer);
}
#endif

static const char *color_grep_slots[] = {
	[GREP_COLOR_CONTEXT]	    = "context",
	[GREP_COLOR_FILENAME]	    = "filename",
	[GREP_COLOR_FUNCTION]	    = "function",
	[GREP_COLOR_LINENO]	    = "lineNumber",
	[GREP_COLOR_COLUMNNO]	    = "column",
	[GREP_COLOR_MATCH_CONTEXT]  = "matchContext",
	[GREP_COLOR_MATCH_SELECTED] = "matchSelected",
	[GREP_COLOR_SELECTED]	    = "selected",
	[GREP_COLOR_SEP]	    = "separator",
};

static void std_output(struct grep_opt *opt, const void *buf, size_t size)
{
	fwrite(buf, size, 1, stdout);
}

static void color_set(char *dst, const char *color_bytes)
{
	xsnprintf(dst, COLOR_MAXLEN, "%s", color_bytes);
}

/*
 * Initialize the grep_defaults template with hardcoded defaults.
 * We could let the compiler do this, but without C99 initializers
 * the code gets unwieldy and unreadable, so...
 */
void init_grep_defaults(struct repository *repo)
{
	struct grep_opt *opt = &grep_defaults;
	static int run_once;

	if (run_once)
		return;
	run_once++;

	memset(opt, 0, sizeof(*opt));
	opt->repo = repo;
	opt->relative = 1;
	opt->pathname = 1;
	opt->max_depth = -1;
	opt->pattern_type_option = GREP_PATTERN_TYPE_UNSPECIFIED;
	color_set(opt->colors[GREP_COLOR_CONTEXT], "");
	color_set(opt->colors[GREP_COLOR_FILENAME], "");
	color_set(opt->colors[GREP_COLOR_FUNCTION], "");
	color_set(opt->colors[GREP_COLOR_LINENO], "");
	color_set(opt->colors[GREP_COLOR_COLUMNNO], "");
	color_set(opt->colors[GREP_COLOR_MATCH_CONTEXT], GIT_COLOR_BOLD_RED);
	color_set(opt->colors[GREP_COLOR_MATCH_SELECTED], GIT_COLOR_BOLD_RED);
	color_set(opt->colors[GREP_COLOR_SELECTED], "");
	color_set(opt->colors[GREP_COLOR_SEP], GIT_COLOR_CYAN);
	opt->only_matching = 0;
	opt->color = -1;
	opt->output = std_output;
}

static int parse_pattern_type_arg(const char *opt, const char *arg)
{
	if (!strcmp(arg, "default"))
		return GREP_PATTERN_TYPE_UNSPECIFIED;
	else if (!strcmp(arg, "basic"))
		return GREP_PATTERN_TYPE_BRE;
	else if (!strcmp(arg, "extended"))
		return GREP_PATTERN_TYPE_ERE;
	else if (!strcmp(arg, "fixed"))
		return GREP_PATTERN_TYPE_FIXED;
	else if (!strcmp(arg, "perl"))
		return GREP_PATTERN_TYPE_PCRE;
	die("bad %s argument: %s", opt, arg);
}

define_list_config_array_extra(color_grep_slots, {"match"});

/*
 * Read the configuration file once and store it in
 * the grep_defaults template.
 */
int grep_config(const char *var, const char *value, void *cb)
{
	struct grep_opt *opt = &grep_defaults;
	const char *slot;

	if (userdiff_config(var, value) < 0)
		return -1;

	if (!strcmp(var, "grep.extendedregexp")) {
		opt->extended_regexp_option = git_config_bool(var, value);
		return 0;
	}

	if (!strcmp(var, "grep.patterntype")) {
		opt->pattern_type_option = parse_pattern_type_arg(var, value);
		return 0;
	}

	if (!strcmp(var, "grep.linenumber")) {
		opt->linenum = git_config_bool(var, value);
		return 0;
	}
	if (!strcmp(var, "grep.column")) {
		opt->columnnum = git_config_bool(var, value);
		return 0;
	}

	if (!strcmp(var, "grep.fullname")) {
		opt->relative = !git_config_bool(var, value);
		return 0;
	}

	if (!strcmp(var, "color.grep"))
		opt->color = git_config_colorbool(var, value);
	if (!strcmp(var, "color.grep.match")) {
		if (grep_config("color.grep.matchcontext", value, cb) < 0)
			return -1;
		if (grep_config("color.grep.matchselected", value, cb) < 0)
			return -1;
	} else if (skip_prefix(var, "color.grep.", &slot)) {
		int i = LOOKUP_CONFIG(color_grep_slots, slot);
		char *color;

		if (i < 0)
			return -1;
		color = opt->colors[i];
		if (!value)
			return config_error_nonbool(var);
		return color_parse(value, color);
	}
	return 0;
}

/*
 * Initialize one instance of grep_opt and copy the
 * default values from the template we read the configuration
 * information in an earlier call to git_config(grep_config).
 *
 * If using PCRE, make sure that the library is configured
 * to use the same allocator as Git (e.g. nedmalloc on Windows).
 *
 * Any allocated memory needs to be released in grep_destroy().
 */
void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
{
	struct grep_opt *def = &grep_defaults;
	int i;

#if defined(USE_LIBPCRE2)
	if (!pcre2_global_context)
		pcre2_global_context = pcre2_general_context_create(
					pcre2_malloc, pcre2_free, NULL);
#endif

#ifdef USE_LIBPCRE1
	pcre_malloc = malloc;
	pcre_free = free;
#endif

	memset(opt, 0, sizeof(*opt));
	opt->repo = repo;
	opt->prefix = prefix;
	opt->prefix_length = (prefix && *prefix) ? strlen(prefix) : 0;
	opt->pattern_tail = &opt->pattern_list;
	opt->header_tail = &opt->header_list;

	opt->only_matching = def->only_matching;
	opt->color = def->color;
	opt->extended_regexp_option = def->extended_regexp_option;
	opt->pattern_type_option = def->pattern_type_option;
	opt->linenum = def->linenum;
	opt->columnnum = def->columnnum;
	opt->max_depth = def->max_depth;
	opt->pathname = def->pathname;
	opt->relative = def->relative;
	opt->output = def->output;

	for (i = 0; i < NR_GREP_COLORS; i++)
		color_set(opt->colors[i], def->colors[i]);
}

void grep_destroy(void)
{
#ifdef USE_LIBPCRE2
	pcre2_general_context_free(pcre2_global_context);
#endif
}

static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, struct grep_opt *opt)
{
	/*
	 * When committing to the pattern type by setting the relevant
	 * fields in grep_opt it's generally not necessary to zero out
	 * the fields we're not choosing, since they won't have been
	 * set by anything. The extended_regexp_option field is the
	 * only exception to this.
	 *
	 * This is because in the process of parsing grep.patternType
	 * & grep.extendedRegexp we set opt->pattern_type_option and
	 * opt->extended_regexp_option, respectively. We then
	 * internally use opt->extended_regexp_option to see if we're
	 * compiling an ERE. It must be unset if that's not actually
	 * the case.
	 */
	if (pattern_type != GREP_PATTERN_TYPE_ERE &&
	    opt->extended_regexp_option)
		opt->extended_regexp_option = 0;

	switch (pattern_type) {
	case GREP_PATTERN_TYPE_UNSPECIFIED:
		/* fall through */

	case GREP_PATTERN_TYPE_BRE:
		break;

	case GREP_PATTERN_TYPE_ERE:
		opt->extended_regexp_option = 1;
		break;

	case GREP_PATTERN_TYPE_FIXED:
		opt->fixed = 1;
		break;

	case GREP_PATTERN_TYPE_PCRE:
#ifdef USE_LIBPCRE2
		opt->pcre2 = 1;
#else
		/*
		 * It's important that pcre1 always be assigned to
		 * even when there's no USE_LIBPCRE* defined. We still
		 * call the PCRE stub function, it just dies with
		 * "cannot use Perl-compatible regexes[...]".
		 */
		opt->pcre1 = 1;
#endif
		break;
	}
}

void grep_commit_pattern_type(enum grep_pattern_type pattern_type, struct grep_opt *opt)
{
	if (pattern_type != GREP_PATTERN_TYPE_UNSPECIFIED)
		grep_set_pattern_type_option(pattern_type, opt);
	else if (opt->pattern_type_option != GREP_PATTERN_TYPE_UNSPECIFIED)
		grep_set_pattern_type_option(opt->pattern_type_option, opt);
	else if (opt->extended_regexp_option)
		/*
		 * This branch *must* happen after setting from the
		 * opt->pattern_type_option above, we don't want
		 * grep.extendedRegexp to override grep.patternType!
		 */
		grep_set_pattern_type_option(GREP_PATTERN_TYPE_ERE, opt);
}

static struct grep_pat *create_grep_pat(const char *pat, size_t patlen,
					const char *origin, int no,
					enum grep_pat_token t,
					enum grep_header_field field)
{
	struct grep_pat *p = xcalloc(1, sizeof(*p));
	p->pattern = xmemdupz(pat, patlen);
	p->patternlen = patlen;
	p->origin = origin;
	p->no = no;
	p->token = t;
	p->field = field;
	return p;
}

static void do_append_grep_pat(struct grep_pat ***tail, struct grep_pat *p)
{
	**tail = p;
	*tail = &p->next;
	p->next = NULL;

	switch (p->token) {
	case GREP_PATTERN: /* atom */
	case GREP_PATTERN_HEAD:
	case GREP_PATTERN_BODY:
		for (;;) {
			struct grep_pat *new_pat;
			size_t len = 0;
			char *cp = p->pattern + p->patternlen, *nl = NULL;
			while (++len <= p->patternlen) {
				if (*(--cp) == '\n') {
					nl = cp;
					break;
				}
			}
			if (!nl)
				break;
			new_pat = create_grep_pat(nl + 1, len - 1, p->origin,
						  p->no, p->token, p->field);
			new_pat->next = p->next;
			if (!p->next)
				*tail = &new_pat->next;
			p->next = new_pat;
			*nl = '\0';
			p->patternlen -= len;
		}
		break;
	default:
		break;
	}
}

void append_header_grep_pattern(struct grep_opt *opt,
				enum grep_header_field field, const char *pat)
{
	struct grep_pat *p = create_grep_pat(pat, strlen(pat), "header", 0,
					     GREP_PATTERN_HEAD, field);
	if (field == GREP_HEADER_REFLOG)
		opt->use_reflog_filter = 1;
	do_append_grep_pat(&opt->header_tail, p);
}

void append_grep_pattern(struct grep_opt *opt, const char *pat,
			 const char *origin, int no, enum grep_pat_token t)
{
	append_grep_pat(opt, pat, strlen(pat), origin, no, t);
}

void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen,
		     const char *origin, int no, enum grep_pat_token t)
{
	struct grep_pat *p = create_grep_pat(pat, patlen, origin, no, t, 0);
	do_append_grep_pat(&opt->pattern_tail, p);
}

struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
{
	struct grep_pat *pat;
	struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
	*ret = *opt;

	ret->pattern_list = NULL;
	ret->pattern_tail = &ret->pattern_list;

	for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
	{
		if(pat->token == GREP_PATTERN_HEAD)
			append_header_grep_pattern(ret, pat->field,
						   pat->pattern);
		else
			append_grep_pat(ret, pat->pattern, pat->patternlen,
					pat->origin, pat->no, pat->token);
	}

	return ret;
}

static NORETURN void compile_regexp_failed(const struct grep_pat *p,
		const char *error)
{
	char where[1024];

	if (p->no)
		xsnprintf(where, sizeof(where), "In '%s' at %d, ", p->origin, p->no);
	else if (p->origin)
		xsnprintf(where, sizeof(where), "%s, ", p->origin);
	else
		where[0] = 0;

	die("%s'%s': %s", where, p->pattern, error);
}

static int is_fixed(const char *s, size_t len)
{
	size_t i;

	for (i = 0; i < len; i++) {
		if (is_regex_special(s[i]))
			return 0;
	}

	return 1;
}

#ifdef USE_LIBPCRE1
static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
{
	const char *error;
	int erroffset;
	int options = PCRE_MULTILINE;
	int study_options = 0;

	if (opt->ignore_case) {
		if (!opt->ignore_locale && has_non_ascii(p->pattern))
			p->pcre1_tables = pcre_maketables();
		options |= PCRE_CASELESS;
	}
	if (!opt->ignore_locale && is_utf8_locale() && has_non_ascii(p->pattern))
		options |= PCRE_UTF8;

	p->pcre1_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
				      p->pcre1_tables);
	if (!p->pcre1_regexp)
		compile_regexp_failed(p, error);

#if defined(PCRE_CONFIG_JIT) && !defined(NO_LIBPCRE1_JIT)
	pcre_config(PCRE_CONFIG_JIT, &p->pcre1_jit_on);
	if (opt->debug)
		fprintf(stderr, "pcre1_jit_on=%d\n", p->pcre1_jit_on);

	if (p->pcre1_jit_on)
		study_options = PCRE_STUDY_JIT_COMPILE;
#endif

	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, study_options, &error);
	if (!p->pcre1_extra_info && error)
		die("%s", error);
}

static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
		regmatch_t *match, int eflags)
{
	int ovector[30], ret, flags = PCRE_NO_UTF8_CHECK;

	if (eflags & REG_NOTBOL)
		flags |= PCRE_NOTBOL;

	ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
			eol - line, 0, flags, ovector,
			ARRAY_SIZE(ovector));

	if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
		die("pcre_exec failed with error code %d", ret);
	if (ret > 0) {
		ret = 0;
		match->rm_so = ovector[0];
		match->rm_eo = ovector[1];
	}

	return ret;
}

static void free_pcre1_regexp(struct grep_pat *p)
{
	pcre_free(p->pcre1_regexp);
#ifdef PCRE_CONFIG_JIT
	if (p->pcre1_jit_on)
		pcre_free_study(p->pcre1_extra_info);
	else
#endif
		pcre_free(p->pcre1_extra_info);
	pcre_free((void *)p->pcre1_tables);
}
#else /* !USE_LIBPCRE1 */
static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
{
	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
}

static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
		regmatch_t *match, int eflags)
{
	return 1;
}

static void free_pcre1_regexp(struct grep_pat *p)
{
}
#endif /* !USE_LIBPCRE1 */

#ifdef USE_LIBPCRE2
static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
{
	int error;
	PCRE2_UCHAR errbuf[256];
	PCRE2_SIZE erroffset;
	int options = PCRE2_MULTILINE;
	int jitret;
	int patinforet;
	size_t jitsizearg;

	assert(opt->pcre2);

	p->pcre2_compile_context = NULL;

	/* pcre2_global_context is initialized in append_grep_pattern */
	if (opt->ignore_case) {
		if (!opt->ignore_locale && has_non_ascii(p->pattern)) {
			if (!pcre2_global_context)
				BUG("pcre2_global_context uninitialized");
			p->pcre2_tables = pcre2_maketables(pcre2_global_context);
			p->pcre2_compile_context = pcre2_compile_context_create(NULL);
			pcre2_set_character_tables(p->pcre2_compile_context,
							p->pcre2_tables);
		}
		options |= PCRE2_CASELESS;
	}
	if (!opt->ignore_locale && is_utf8_locale() && has_non_ascii(p->pattern) &&
	    !(!opt->ignore_case && (p->fixed || p->is_fixed)))
		options |= PCRE2_UTF;

	p->pcre2_pattern = pcre2_compile((PCRE2_SPTR)p->pattern,
					 p->patternlen, options, &error, &erroffset,
					 p->pcre2_compile_context);

	if (p->pcre2_pattern) {
		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, NULL);
		if (!p->pcre2_match_data)
			die("Couldn't allocate PCRE2 match data");
	} else {
		pcre2_get_error_message(error, errbuf, sizeof(errbuf));
		compile_regexp_failed(p, (const char *)&errbuf);
	}

	pcre2_config(PCRE2_CONFIG_JIT, &p->pcre2_jit_on);
	if (opt->debug)
		fprintf(stderr, "pcre2_jit_on=%d\n", p->pcre2_jit_on);
	if (p->pcre2_jit_on) {
		jitret = pcre2_jit_compile(p->pcre2_pattern, PCRE2_JIT_COMPLETE);
		if (jitret)
			die("Couldn't JIT the PCRE2 pattern '%s', got '%d'\n", p->pattern, jitret);

		/*
		 * The pcre2_config(PCRE2_CONFIG_JIT, ...) call just
		 * tells us whether the library itself supports JIT,
		 * but to see whether we're going to be actually using
		 * JIT we need to extract PCRE2_INFO_JITSIZE from the
		 * pattern *after* we do pcre2_jit_compile() above.
		 *
		 * This is because if the pattern contains the
		 * (*NO_JIT) verb (see pcre2syntax(3))
		 * pcre2_jit_compile() will exit early with 0. If we
		 * then proceed to call pcre2_jit_match() further down
		 * the line instead of pcre2_match() we'll either
		 * segfault (pre PCRE 10.31) or run into a fatal error
		 * (post PCRE2 10.31)
		 */
		patinforet = pcre2_pattern_info(p->pcre2_pattern, PCRE2_INFO_JITSIZE, &jitsizearg);
		if (patinforet)
			BUG("pcre2_pattern_info() failed: %d", patinforet);
		if (jitsizearg == 0) {
			p->pcre2_jit_on = 0;
			if (opt->debug)
				fprintf(stderr, "pcre2_jit_on=%d: (*NO_JIT) in regex\n",
					p->pcre2_jit_on);
			return;
		}
	}
}

static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
		regmatch_t *match, int eflags)
{
	int ret, flags = 0;
	PCRE2_SIZE *ovector;
	PCRE2_UCHAR errbuf[256];

	if (eflags & REG_NOTBOL)
		flags |= PCRE2_NOTBOL;

	if (p->pcre2_jit_on)
		ret = pcre2_jit_match(p->pcre2_pattern, (unsigned char *)line,
				      eol - line, 0, flags, p->pcre2_match_data,
				      NULL);
	else
		ret = pcre2_match(p->pcre2_pattern, (unsigned char *)line,
				  eol - line, 0, flags, p->pcre2_match_data,
				  NULL);

	if (ret < 0 && ret != PCRE2_ERROR_NOMATCH) {
		pcre2_get_error_message(ret, errbuf, sizeof(errbuf));
		die("%s failed with error code %d: %s",
		    (p->pcre2_jit_on ? "pcre2_jit_match" : "pcre2_match"), ret,
		    errbuf);
	}
	if (ret > 0) {
		ovector = pcre2_get_ovector_pointer(p->pcre2_match_data);
		ret = 0;
		match->rm_so = (int)ovector[0];
		match->rm_eo = (int)ovector[1];
	}

	return ret;
}

static void free_pcre2_pattern(struct grep_pat *p)
{
	pcre2_compile_context_free(p->pcre2_compile_context);
	pcre2_code_free(p->pcre2_pattern);
	pcre2_match_data_free(p->pcre2_match_data);
	free((void *)p->pcre2_tables);
}
#else /* !USE_LIBPCRE2 */
static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
{
	/*
	 * Unreachable until USE_LIBPCRE2 becomes synonymous with
	 * USE_LIBPCRE. See the sibling comment in
	 * grep_set_pattern_type_option().
	 */
	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
}

static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
		regmatch_t *match, int eflags)
{
	return 1;
}

static void free_pcre2_pattern(struct grep_pat *p)
{
}

static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
{
	struct strbuf sb = STRBUF_INIT;
	int err;
	int regflags = 0;

	basic_regex_quote_buf(&sb, p->pattern);
	if (opt->ignore_case)
		regflags |= REG_ICASE;
	err = regcomp(&p->regexp, sb.buf, regflags);
	if (opt->debug)
		fprintf(stderr, "fixed %s\n", sb.buf);
	strbuf_release(&sb);
	if (err) {
		char errbuf[1024];
		regerror(err, &p->regexp, errbuf, sizeof(errbuf));
		compile_regexp_failed(p, errbuf);
	}
}
#endif /* !USE_LIBPCRE2 */

static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
{
	int err;
	int regflags = REG_NEWLINE;

	p->word_regexp = opt->word_regexp;
	p->ignore_case = opt->ignore_case;
	p->fixed = opt->fixed;

	if (memchr(p->pattern, 0, p->patternlen) && !opt->pcre2)
		die(_("given pattern contains NULL byte (via -f <file>). This is only supported with -P under PCRE v2"));

	p->is_fixed = is_fixed(p->pattern, p->patternlen);
#ifdef USE_LIBPCRE2
       if (!p->fixed && !p->is_fixed) {
	       const char *no_jit = "(*NO_JIT)";
	       const int no_jit_len = strlen(no_jit);
	       if (starts_with(p->pattern, no_jit) &&
		   is_fixed(p->pattern + no_jit_len,
			    p->patternlen - no_jit_len))
		       p->is_fixed = 1;
       }
#endif
	if (p->fixed || p->is_fixed) {
#ifdef USE_LIBPCRE2
		opt->pcre2 = 1;
		if (p->is_fixed) {
			compile_pcre2_pattern(p, opt);
		} else {
			/*
			 * E.g. t7811-grep-open.sh relies on the
			 * pattern being restored.
			 */
			char *old_pattern = p->pattern;
			size_t old_patternlen = p->patternlen;
			struct strbuf sb = STRBUF_INIT;

			/*
			 * There is the PCRE2_LITERAL flag, but it's
			 * only in PCRE v2 10.30 and later. Needing to
			 * ifdef our way around that and dealing with
			 * it + PCRE2_MULTILINE being an error is more
			 * complex than just quoting this ourselves.
			*/
			strbuf_add(&sb, "\\Q", 2);
			strbuf_add(&sb, p->pattern, p->patternlen);
			strbuf_add(&sb, "\\E", 2);

			p->pattern = sb.buf;
			p->patternlen = sb.len;
			compile_pcre2_pattern(p, opt);
			p->pattern = old_pattern;
			p->patternlen = old_patternlen;
			strbuf_release(&sb);
		}
#else /* !USE_LIBPCRE2 */
		compile_fixed_regexp(p, opt);
#endif /* !USE_LIBPCRE2 */
		return;
	}

	if (opt->pcre2) {
		compile_pcre2_pattern(p, opt);
		return;
	}

	if (opt->pcre1) {
		compile_pcre1_regexp(p, opt);
		return;
	}

	if (p->ignore_case)
		regflags |= REG_ICASE;
	if (opt->extended_regexp_option)
		regflags |= REG_EXTENDED;
	err = regcomp(&p->regexp, p->pattern, regflags);
	if (err) {
		char errbuf[1024];
		regerror(err, &p->regexp, errbuf, 1024);
		compile_regexp_failed(p, errbuf);
	}
}

static struct grep_expr *compile_pattern_or(struct grep_pat **);
static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
{
	struct grep_pat *p;
	struct grep_expr *x;

	p = *list;
	if (!p)
		return NULL;
	switch (p->token) {
	case GREP_PATTERN: /* atom */
	case GREP_PATTERN_HEAD:
	case GREP_PATTERN_BODY:
		x = xcalloc(1, sizeof (struct grep_expr));
		x->node = GREP_NODE_ATOM;
		x->u.atom = p;
		*list = p->next;
		return x;
	case GREP_OPEN_PAREN:
		*list = p->next;
		x = compile_pattern_or(list);
		if (!*list || (*list)->token != GREP_CLOSE_PAREN)
			die("unmatched parenthesis");
		*list = (*list)->next;
		return x;
	default:
		return NULL;
	}
}

static struct grep_expr *compile_pattern_not(struct grep_pat **list)
{
	struct grep_pat *p;
	struct grep_expr *x;

	p = *list;
	if (!p)
		return NULL;
	switch (p->token) {
	case GREP_NOT:
		if (!p->next)
			die("--not not followed by pattern expression");
		*list = p->next;
		x = xcalloc(1, sizeof (struct grep_expr));
		x->node = GREP_NODE_NOT;
		x->u.unary = compile_pattern_not(list);
		if (!x->u.unary)
			die("--not followed by non pattern expression");
		return x;
	default:
		return compile_pattern_atom(list);
	}
}

static struct grep_expr *compile_pattern_and(struct grep_pat **list)
{
	struct grep_pat *p;
	struct grep_expr *x, *y, *z;

	x = compile_pattern_not(list);
	p = *list;
	if (p && p->token == GREP_AND) {
		if (!p->next)
			die("--and not followed by pattern expression");
		*list = p->next;
		y = compile_pattern_and(list);
		if (!y)
			die("--and not followed by pattern expression");
		z = xcalloc(1, sizeof (struct grep_expr));
		z->node = GREP_NODE_AND;
		z->u.binary.left = x;
		z->u.binary.right = y;
		return z;
	}
	return x;
}

static struct grep_expr *compile_pattern_or(struct grep_pat **list)
{
	struct grep_pat *p;
	struct grep_expr *x, *y, *z;

	x = compile_pattern_and(list);
	p = *list;
	if (x && p && p->token != GREP_CLOSE_PAREN) {
		y = compile_pattern_or(list);
		if (!y)
			die("not a pattern expression %s", p->pattern);
		z = xcalloc(1, sizeof (struct grep_expr));
		z->node = GREP_NODE_OR;
		z->u.binary.left = x;
		z->u.binary.right = y;
		return z;
	}
	return x;
}

static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
{
	return compile_pattern_or(list);
}

static void indent(int in)
{
	while (in-- > 0)
		fputc(' ', stderr);
}

static void dump_grep_pat(struct grep_pat *p)
{
	switch (p->token) {
	case GREP_AND: fprintf(stderr, "*and*"); break;
	case GREP_OPEN_PAREN: fprintf(stderr, "*(*"); break;
	case GREP_CLOSE_PAREN: fprintf(stderr, "*)*"); break;
	case GREP_NOT: fprintf(stderr, "*not*"); break;
	case GREP_OR: fprintf(stderr, "*or*"); break;

	case GREP_PATTERN: fprintf(stderr, "pattern"); break;
	case GREP_PATTERN_HEAD: fprintf(stderr, "pattern_head"); break;
	case GREP_PATTERN_BODY: fprintf(stderr, "pattern_body"); break;
	}

	switch (p->token) {
	default: break;
	case GREP_PATTERN_HEAD:
		fprintf(stderr, "<head %d>", p->field); break;
	case GREP_PATTERN_BODY:
		fprintf(stderr, "<body>"); break;
	}
	switch (p->token) {
	default: break;
	case GREP_PATTERN_HEAD:
	case GREP_PATTERN_BODY:
	case GREP_PATTERN:
		fprintf(stderr, "%.*s", (int)p->patternlen, p->pattern);
		break;
	}
	fputc('\n', stderr);
}

static void dump_grep_expression_1(struct grep_expr *x, int in)
{
	indent(in);
	switch (x->node) {
	case GREP_NODE_TRUE:
		fprintf(stderr, "true\n");
		break;
	case GREP_NODE_ATOM:
		dump_grep_pat(x->u.atom);
		break;
	case GREP_NODE_NOT:
		fprintf(stderr, "(not\n");
		dump_grep_expression_1(x->u.unary, in+1);
		indent(in);
		fprintf(stderr, ")\n");
		break;
	case GREP_NODE_AND:
		fprintf(stderr, "(and\n");
		dump_grep_expression_1(x->u.binary.left, in+1);
		dump_grep_expression_1(x->u.binary.right, in+1);
		indent(in);
		fprintf(stderr, ")\n");
		break;
	case GREP_NODE_OR:
		fprintf(stderr, "(or\n");
		dump_grep_expression_1(x->u.binary.left, in+1);
		dump_grep_expression_1(x->u.binary.right, in+1);
		indent(in);
		fprintf(stderr, ")\n");
		break;
	}
}

static void dump_grep_expression(struct grep_opt *opt)
{
	struct grep_expr *x = opt->pattern_expression;

	if (opt->all_match)
		fprintf(stderr, "[all-match]\n");
	dump_grep_expression_1(x, 0);
	fflush(NULL);
}

static struct grep_expr *grep_true_expr(void)
{
	struct grep_expr *z = xcalloc(1, sizeof(*z));
	z->node = GREP_NODE_TRUE;
	return z;
}

static struct grep_expr *grep_or_expr(struct grep_expr *left, struct grep_expr *right)
{
	struct grep_expr *z = xcalloc(1, sizeof(*z));
	z->node = GREP_NODE_OR;
	z->u.binary.left = left;
	z->u.binary.right = right;
	return z;
}

static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
{
	struct grep_pat *p;
	struct grep_expr *header_expr;
	struct grep_expr *(header_group[GREP_HEADER_FIELD_MAX]);
	enum grep_header_field fld;

	if (!opt->header_list)
		return NULL;

	for (p = opt->header_list; p; p = p->next) {
		if (p->token != GREP_PATTERN_HEAD)
			BUG("a non-header pattern in grep header list.");
		if (p->field < GREP_HEADER_FIELD_MIN ||
		    GREP_HEADER_FIELD_MAX <= p->field)
			BUG("unknown header field %d", p->field);
		compile_regexp(p, opt);
	}

	for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++)
		header_group[fld] = NULL;

	for (p = opt->header_list; p; p = p->next) {
		struct grep_expr *h;
		struct grep_pat *pp = p;

		h = compile_pattern_atom(&pp);
		if (!h || pp != p->next)
			BUG("malformed header expr");
		if (!header_group[p->field]) {
			header_group[p->field] = h;
			continue;
		}
		header_group[p->field] = grep_or_expr(h, header_group[p->field]);
	}

	header_expr = NULL;

	for (fld = 0; fld < GREP_HEADER_FIELD_MAX; fld++) {
		if (!header_group[fld])
			continue;
		if (!header_expr)
			header_expr = grep_true_expr();
		header_expr = grep_or_expr(header_group[fld], header_expr);
	}
	return header_expr;
}

static struct grep_expr *grep_splice_or(struct grep_expr *x, struct grep_expr *y)
{
	struct grep_expr *z = x;

	while (x) {
		assert(x->node == GREP_NODE_OR);
		if (x->u.binary.right &&
		    x->u.binary.right->node == GREP_NODE_TRUE) {
			x->u.binary.right = y;
			break;
		}
		x = x->u.binary.right;
	}
	return z;
}

static void compile_grep_patterns_real(struct grep_opt *opt)
{
	struct grep_pat *p;
	struct grep_expr *header_expr = prep_header_patterns(opt);

	for (p = opt->pattern_list; p; p = p->next) {
		switch (p->token) {
		case GREP_PATTERN: /* atom */
		case GREP_PATTERN_HEAD:
		case GREP_PATTERN_BODY:
			compile_regexp(p, opt);
			break;
		default:
			opt->extended = 1;
			break;
		}
	}

	if (opt->all_match || header_expr)
		opt->extended = 1;
	else if (!opt->extended && !opt->debug)
		return;

	p = opt->pattern_list;
	if (p)
		opt->pattern_expression = compile_pattern_expr(&p);
	if (p)
		die("incomplete pattern expression: %s", p->pattern);

	if (!header_expr)
		return;

	if (!opt->pattern_expression)
		opt->pattern_expression = header_expr;
	else if (opt->all_match)
		opt->pattern_expression = grep_splice_or(header_expr,
							 opt->pattern_expression);
	else
		opt->pattern_expression = grep_or_expr(opt->pattern_expression,
						       header_expr);
	opt->all_match = 1;
}

void compile_grep_patterns(struct grep_opt *opt)
{
	compile_grep_patterns_real(opt);
	if (opt->debug)
		dump_grep_expression(opt);
}

static void free_pattern_expr(struct grep_expr *x)
{
	switch (x->node) {
	case GREP_NODE_TRUE:
	case GREP_NODE_ATOM:
		break;
	case GREP_NODE_NOT:
		free_pattern_expr(x->u.unary);
		break;
	case GREP_NODE_AND:
	case GREP_NODE_OR:
		free_pattern_expr(x->u.binary.left);
		free_pattern_expr(x->u.binary.right);
		break;
	}
	free(x);
}

void free_grep_patterns(struct grep_opt *opt)
{
	struct grep_pat *p, *n;

	for (p = opt->pattern_list; p; p = n) {
		n = p->next;
		switch (p->token) {
		case GREP_PATTERN: /* atom */
		case GREP_PATTERN_HEAD:
		case GREP_PATTERN_BODY:
			if (p->pcre1_regexp)
				free_pcre1_regexp(p);
			else if (p->pcre2_pattern)
				free_pcre2_pattern(p);
			else
				regfree(&p->regexp);
			free(p->pattern);
			break;
		default:
			break;
		}
		free(p);
	}

	if (!opt->extended)
		return;
	free_pattern_expr(opt->pattern_expression);
}

static char *end_of_line(char *cp, unsigned long *left)
{
	unsigned long l = *left;
	while (l && *cp != '\n') {
		l--;
		cp++;
	}
	*left = l;
	return cp;
}

static int word_char(char ch)
{
	return isalnum(ch) || ch == '_';
}

static void output_color(struct grep_opt *opt, const void *data, size_t size,
			 const char *color)
{
	if (want_color(opt->color) && color && color[0]) {
		opt->output(opt, color, strlen(color));
		opt->output(opt, data, size);
		opt->output(opt, GIT_COLOR_RESET, strlen(GIT_COLOR_RESET));
	} else
		opt->output(opt, data, size);
}

static void output_sep(struct grep_opt *opt, char sign)
{
	if (opt->null_following_name)
		opt->output(opt, "\0", 1);
	else
		output_color(opt, &sign, 1, opt->colors[GREP_COLOR_SEP]);
}

static void show_name(struct grep_opt *opt, const char *name)
{
	output_color(opt, name, strlen(name), opt->colors[GREP_COLOR_FILENAME]);
	opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
}

static int patmatch(struct grep_pat *p, char *line, char *eol,
		    regmatch_t *match, int eflags)
{
	int hit;

	if (p->pcre1_regexp)
		hit = !pcre1match(p, line, eol, match, eflags);
	else if (p->pcre2_pattern)
		hit = !pcre2match(p, line, eol, match, eflags);
	else
		hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
				   eflags);

	return hit;
}

static int strip_timestamp(char *bol, char **eol_p)
{
	char *eol = *eol_p;
	int ch;

	while (bol < --eol) {
		if (*eol != '>')
			continue;
		*eol_p = ++eol;
		ch = *eol;
		*eol = '\0';
		return ch;
	}
	return 0;
}

static struct {
	const char *field;
	size_t len;
} header_field[] = {
	{ "author ", 7 },
	{ "committer ", 10 },
	{ "reflog ", 7 },
};

static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
			     enum grep_context ctx,
			     regmatch_t *pmatch, int eflags)
{
	int hit = 0;
	int saved_ch = 0;
	const char *start = bol;

	if ((p->token != GREP_PATTERN) &&
	    ((p->token == GREP_PATTERN_HEAD) != (ctx == GREP_CONTEXT_HEAD)))
		return 0;

	if (p->token == GREP_PATTERN_HEAD) {
		const char *field;
		size_t len;
		assert(p->field < ARRAY_SIZE(header_field));
		field = header_field[p->field].field;
		len = header_field[p->field].len;
		if (strncmp(bol, field, len))
			return 0;
		bol += len;
		switch (p->field) {
		case GREP_HEADER_AUTHOR:
		case GREP_HEADER_COMMITTER:
			saved_ch = strip_timestamp(bol, &eol);
			break;
		default:
			break;
		}
	}

 again:
	hit = patmatch(p, bol, eol, pmatch, eflags);

	if (hit && p->word_regexp) {
		if ((pmatch[0].rm_so < 0) ||
		    (eol - bol) < pmatch[0].rm_so ||
		    (pmatch[0].rm_eo < 0) ||
		    (eol - bol) < pmatch[0].rm_eo)
			die("regexp returned nonsense");

		/* Match beginning must be either beginning of the
		 * line, or at word boundary (i.e. the last char must
		 * not be a word char).  Similarly, match end must be
		 * either end of the line, or at word boundary
		 * (i.e. the next char must not be a word char).
		 */
		if ( ((pmatch[0].rm_so == 0) ||
		      !word_char(bol[pmatch[0].rm_so-1])) &&
		     ((pmatch[0].rm_eo == (eol-bol)) ||
		      !word_char(bol[pmatch[0].rm_eo])) )
			;
		else
			hit = 0;

		/* Words consist of at least one character. */
		if (pmatch->rm_so == pmatch->rm_eo)
			hit = 0;

		if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
			/* There could be more than one match on the
			 * line, and the first match might not be
			 * strict word match.  But later ones could be!
			 * Forward to the next possible start, i.e. the
			 * next position following a non-word char.
			 */
			bol = pmatch[0].rm_so + bol + 1;
			while (word_char(bol[-1]) && bol < eol)
				bol++;
			eflags |= REG_NOTBOL;
			if (bol < eol)
				goto again;
		}
	}
	if (p->token == GREP_PATTERN_HEAD && saved_ch)
		*eol = saved_ch;
	if (hit) {
		pmatch[0].rm_so += bol - start;
		pmatch[0].rm_eo += bol - start;
	}
	return hit;
}

static int match_expr_eval(struct grep_opt *opt, struct grep_expr *x, char *bol,
			   char *eol, enum grep_context ctx, ssize_t *col,
			   ssize_t *icol, int collect_hits)
{
	int h = 0;

	if (!x)
		die("Not a valid grep expression");
	switch (x->node) {
	case GREP_NODE_TRUE:
		h = 1;
		break;
	case GREP_NODE_ATOM:
		{
			regmatch_t tmp;
			h = match_one_pattern(x->u.atom, bol, eol, ctx,
					      &tmp, 0);
			if (h && (*col < 0 || tmp.rm_so < *col))
				*col = tmp.rm_so;
		}
		break;
	case GREP_NODE_NOT:
		/*
		 * Upon visiting a GREP_NODE_NOT, col and icol become swapped.
		 */
		h = !match_expr_eval(opt, x->u.unary, bol, eol, ctx, icol, col,
				     0);
		break;
	case GREP_NODE_AND:
		h = match_expr_eval(opt, x->u.binary.left, bol, eol, ctx, col,
				    icol, 0);
		if (h || opt->columnnum) {
			/*
			 * Don't short-circuit AND when given --column, since a
			 * NOT earlier in the tree may turn this into an OR. In
			 * this case, see the below comment.
			 */
			h &= match_expr_eval(opt, x->u.binary.right, bol, eol,
					     ctx, col, icol, 0);
		}
		break;
	case GREP_NODE_OR:
		if (!(collect_hits || opt->columnnum)) {
			/*
			 * Don't short-circuit OR when given --column (or
			 * collecting hits) to ensure we don't skip a later
			 * child that would produce an earlier match.
			 */
			return (match_expr_eval(opt, x->u.binary.left, bol, eol,
						ctx, col, icol, 0) ||
				match_expr_eval(opt, x->u.binary.right, bol,
						eol, ctx, col, icol, 0));
		}
		h = match_expr_eval(opt, x->u.binary.left, bol, eol, ctx, col,
				    icol, 0);
		if (collect_hits)
			x->u.binary.left->hit |= h;
		h |= match_expr_eval(opt, x->u.binary.right, bol, eol, ctx, col,
				     icol, collect_hits);
		break;
	default:
		die("Unexpected node type (internal error) %d", x->node);
	}
	if (collect_hits)
		x->hit |= h;
	return h;
}

static int match_expr(struct grep_opt *opt, char *bol, char *eol,
		      enum grep_context ctx, ssize_t *col,
		      ssize_t *icol, int collect_hits)
{
	struct grep_expr *x = opt->pattern_expression;
	return match_expr_eval(opt, x, bol, eol, ctx, col, icol, collect_hits);
}

static int match_line(struct grep_opt *opt, char *bol, char *eol,
		      ssize_t *col, ssize_t *icol,
		      enum grep_context ctx, int collect_hits)
{
	struct grep_pat *p;
	int hit = 0;

	if (opt->extended)
		return match_expr(opt, bol, eol, ctx, col, icol,
				  collect_hits);

	/* we do not call with collect_hits without being extended */
	for (p = opt->pattern_list; p; p = p->next) {
		regmatch_t tmp;
		if (match_one_pattern(p, bol, eol, ctx, &tmp, 0)) {
			hit |= 1;
			if (!opt->columnnum) {
				/*
				 * Without --column, any single match on a line
				 * is enough to know that it needs to be
				 * printed. With --column, scan _all_ patterns
				 * to find the earliest.
				 */
				break;
			}
			if (*col < 0 || tmp.rm_so < *col)
				*col = tmp.rm_so;
		}
	}
	return hit;
}

static int match_next_pattern(struct grep_pat *p, char *bol, char *eol,
			      enum grep_context ctx,
			      regmatch_t *pmatch, int eflags)
{
	regmatch_t match;

	if (!match_one_pattern(p, bol, eol, ctx, &match, eflags))
		return 0;
	if (match.rm_so < 0 || match.rm_eo < 0)
		return 0;
	if (pmatch->rm_so >= 0 && pmatch->rm_eo >= 0) {
		if (match.rm_so > pmatch->rm_so)
			return 1;
		if (match.rm_so == pmatch->rm_so && match.rm_eo < pmatch->rm_eo)
			return 1;
	}
	pmatch->rm_so = match.rm_so;
	pmatch->rm_eo = match.rm_eo;
	return 1;
}

static int next_match(struct grep_opt *opt, char *bol, char *eol,
		      enum grep_context ctx, regmatch_t *pmatch, int eflags)
{
	struct grep_pat *p;
	int hit = 0;

	pmatch->rm_so = pmatch->rm_eo = -1;
	if (bol < eol) {
		for (p = opt->pattern_list; p; p = p->next) {
			switch (p->token) {
			case GREP_PATTERN: /* atom */
			case GREP_PATTERN_HEAD:
			case GREP_PATTERN_BODY:
				hit |= match_next_pattern(p, bol, eol, ctx,
							  pmatch, eflags);
				break;
			default:
				break;
			}
		}
	}
	return hit;
}

static void show_line_header(struct grep_opt *opt, const char *name,
			     unsigned lno, ssize_t cno, char sign)
{
	if (opt->heading && opt->last_shown == 0) {
		output_color(opt, name, strlen(name), opt->colors[GREP_COLOR_FILENAME]);
		opt->output(opt, "\n", 1);
	}
	opt->last_shown = lno;

	if (!opt->heading && opt->pathname) {
		output_color(opt, name, strlen(name), opt->colors[GREP_COLOR_FILENAME]);
		output_sep(opt, sign);
	}
	if (opt->linenum) {
		char buf[32];
		xsnprintf(buf, sizeof(buf), "%d", lno);
		output_color(opt, buf, strlen(buf), opt->colors[GREP_COLOR_LINENO]);
		output_sep(opt, sign);
	}
	/*
	 * Treat 'cno' as the 1-indexed offset from the start of a non-context
	 * line to its first match. Otherwise, 'cno' is 0 indicating that we are
	 * being called with a context line.
	 */
	if (opt->columnnum && cno) {
		char buf[32];
		xsnprintf(buf, sizeof(buf), "%"PRIuMAX, (uintmax_t)cno);
		output_color(opt, buf, strlen(buf), opt->colors[GREP_COLOR_COLUMNNO]);
		output_sep(opt, sign);
	}
}

static void show_line(struct grep_opt *opt, char *bol, char *eol,
		      const char *name, unsigned lno, ssize_t cno, char sign)
{
	int rest = eol - bol;
	const char *match_color = NULL;
	const char *line_color = NULL;

	if (opt->file_break && opt->last_shown == 0) {
		if (opt->show_hunk_mark)
			opt->output(opt, "\n", 1);
	} else if (opt->pre_context || opt->post_context || opt->funcbody) {
		if (opt->last_shown == 0) {
			if (opt->show_hunk_mark) {
				output_color(opt, "--", 2, opt->colors[GREP_COLOR_SEP]);
				opt->output(opt, "\n", 1);
			}
		} else if (lno > opt->last_shown + 1) {
			output_color(opt, "--", 2, opt->colors[GREP_COLOR_SEP]);
			opt->output(opt, "\n", 1);
		}
	}
	if (!opt->only_matching) {
		/*
		 * In case the line we're being called with contains more than
		 * one match, leave printing each header to the loop below.
		 */
		show_line_header(opt, name, lno, cno, sign);
	}
	if (opt->color || opt->only_matching) {
		regmatch_t match;
		enum grep_context ctx = GREP_CONTEXT_BODY;
		int ch = *eol;
		int eflags = 0;

		if (opt->color) {
			if (sign == ':')
				match_color = opt->colors[GREP_COLOR_MATCH_SELECTED];
			else
				match_color = opt->colors[GREP_COLOR_MATCH_CONTEXT];
			if (sign == ':')
				line_color = opt->colors[GREP_COLOR_SELECTED];
			else if (sign == '-')
				line_color = opt->colors[GREP_COLOR_CONTEXT];
			else if (sign == '=')
				line_color = opt->colors[GREP_COLOR_FUNCTION];
		}
		*eol = '\0';
		while (next_match(opt, bol, eol, ctx, &match, eflags)) {
			if (match.rm_so == match.rm_eo)
				break;

			if (opt->only_matching)
				show_line_header(opt, name, lno, cno, sign);
			else
				output_color(opt, bol, match.rm_so, line_color);
			output_color(opt, bol + match.rm_so,
				     match.rm_eo - match.rm_so, match_color);
			if (opt->only_matching)
				opt->output(opt, "\n", 1);
			bol += match.rm_eo;
			cno += match.rm_eo;
			rest -= match.rm_eo;
			eflags = REG_NOTBOL;
		}
		*eol = ch;
	}
	if (!opt->only_matching) {
		output_color(opt, bol, rest, line_color);
		opt->output(opt, "\n", 1);
	}
}

int grep_use_locks;

/*
 * This lock protects access to the gitattributes machinery, which is
 * not thread-safe.
 */
pthread_mutex_t grep_attr_mutex;

static inline void grep_attr_lock(void)
{
	if (grep_use_locks)
		pthread_mutex_lock(&grep_attr_mutex);
}

static inline void grep_attr_unlock(void)
{
	if (grep_use_locks)
		pthread_mutex_unlock(&grep_attr_mutex);
}

static int match_funcname(struct grep_opt *opt, struct grep_source *gs, char *bol, char *eol)
{
	xdemitconf_t *xecfg = opt->priv;
	if (xecfg && !xecfg->find_func) {
		grep_source_load_driver(gs, opt->repo->index);
		if (gs->driver->funcname.pattern) {
			const struct userdiff_funcname *pe = &gs->driver->funcname;
			xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);
		} else {
			xecfg = opt->priv = NULL;
		}
	}

	if (xecfg) {
		char buf[1];
		return xecfg->find_func(bol, eol - bol, buf, 1,
					xecfg->find_func_priv) >= 0;
	}

	if (bol == eol)
		return 0;
	if (isalpha(*bol) || *bol == '_' || *bol == '$')
		return 1;
	return 0;
}

static void show_funcname_line(struct grep_opt *opt, struct grep_source *gs,
			       char *bol, unsigned lno)
{
	while (bol > gs->buf) {
		char *eol = --bol;

		while (bol > gs->buf && bol[-1] != '\n')
			bol--;
		lno--;

		if (lno <= opt->last_shown)
			break;

		if (match_funcname(opt, gs, bol, eol)) {
			show_line(opt, bol, eol, gs->name, lno, 0, '=');
			break;
		}
	}
}

static int is_empty_line(const char *bol, const char *eol);

static void show_pre_context(struct grep_opt *opt, struct grep_source *gs,
			     char *bol, char *end, unsigned lno)
{
	unsigned cur = lno, from = 1, funcname_lno = 0, orig_from;
	int funcname_needed = !!opt->funcname, comment_needed = 0;

	if (opt->pre_context < lno)
		from = lno - opt->pre_context;
	if (from <= opt->last_shown)
		from = opt->last_shown + 1;
	orig_from = from;
	if (opt->funcbody) {
		if (match_funcname(opt, gs, bol, end))
			comment_needed = 1;
		else
			funcname_needed = 1;
		from = opt->last_shown + 1;
	}

	/* Rewind. */
	while (bol > gs->buf && cur > from) {
		char *next_bol = bol;
		char *eol = --bol;

		while (bol > gs->buf && bol[-1] != '\n')
			bol--;
		cur--;
		if (comment_needed && (is_empty_line(bol, eol) ||
				       match_funcname(opt, gs, bol, eol))) {
			comment_needed = 0;
			from = orig_from;
			if (cur < from) {
				cur++;
				bol = next_bol;
				break;
			}
		}
		if (funcname_needed && match_funcname(opt, gs, bol, eol)) {
			funcname_lno = cur;
			funcname_needed = 0;
			if (opt->funcbody)
				comment_needed = 1;
			else
				from = orig_from;
		}
	}

	/* We need to look even further back to find a function signature. */
	if (opt->funcname && funcname_needed)
		show_funcname_line(opt, gs, bol, cur);

	/* Back forward. */
	while (cur < lno) {
		char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';

		while (*eol != '\n')
			eol++;
		show_line(opt, bol, eol, gs->name, cur, 0, sign);
		bol = eol + 1;
		cur++;
	}
}

static int should_lookahead(struct grep_opt *opt)
{
	struct grep_pat *p;

	if (opt->extended)
		return 0; /* punt for too complex stuff */
	if (opt->invert)
		return 0;
	for (p = opt->pattern_list; p; p = p->next) {
		if (p->token != GREP_PATTERN)
			return 0; /* punt for "header only" and stuff */
	}
	return 1;
}

static int look_ahead(struct grep_opt *opt,
		      unsigned long *left_p,
		      unsigned *lno_p,
		      char **bol_p)
{
	unsigned lno = *lno_p;
	char *bol = *bol_p;
	struct grep_pat *p;
	char *sp, *last_bol;
	regoff_t earliest = -1;

	for (p = opt->pattern_list; p; p = p->next) {
		int hit;
		regmatch_t m;

		hit = patmatch(p, bol, bol + *left_p, &m, 0);
		if (!hit || m.rm_so < 0 || m.rm_eo < 0)
			continue;
		if (earliest < 0 || m.rm_so < earliest)
			earliest = m.rm_so;
	}

	if (earliest < 0) {
		*bol_p = bol + *left_p;
		*left_p = 0;
		return 1;
	}
	for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
		; /* find the beginning of the line */
	last_bol = sp;

	for (sp = bol; sp < last_bol; sp++) {
		if (*sp == '\n')
			lno++;
	}
	*left_p -= last_bol - bol;
	*bol_p = last_bol;
	*lno_p = lno;
	return 0;
}

static int fill_textconv_grep(struct repository *r,
			      struct userdiff_driver *driver,
			      struct grep_source *gs)
{
	struct diff_filespec *df;
	char *buf;
	size_t size;

	if (!driver || !driver->textconv)
		return grep_source_load(gs);

	/*
	 * The textconv interface is intimately tied to diff_filespecs, so we
	 * have to pretend to be one. If we could unify the grep_source
	 * and diff_filespec structs, this mess could just go away.
	 */
	df = alloc_filespec(gs->path);
	switch (gs->type) {
	case GREP_SOURCE_OID:
		fill_filespec(df, gs->identifier, 1, 0100644);
		break;
	case GREP_SOURCE_FILE:
		fill_filespec(df, &null_oid, 0, 0100644);
		break;
	default:
		BUG("attempt to textconv something without a path?");
	}

	/*
	 * fill_textconv is not remotely thread-safe; it modifies the global
	 * diff tempfile structure, writes to the_repo's odb and might
	 * internally call thread-unsafe functions such as the
	 * prepare_packed_git() lazy-initializator. Because of the last two, we
	 * must ensure mutual exclusion between this call and the object reading
	 * API, thus we use obj_read_lock() here.
	 *
	 * TODO: allowing text conversion to run in parallel with object
	 * reading operations might increase performance in the multithreaded
	 * non-worktreee git-grep with --textconv.
	 */
	obj_read_lock();
	size = fill_textconv(r, driver, df, &buf);
	obj_read_unlock();
	free_filespec(df);

	/*
	 * The normal fill_textconv usage by the diff machinery would just keep
	 * the textconv'd buf separate from the diff_filespec. But much of the
	 * grep code passes around a grep_source and assumes that its "buf"
	 * pointer is the beginning of the thing we are searching. So let's
	 * install our textconv'd version into the grep_source, taking care not
	 * to leak any existing buffer.
	 */
	grep_source_clear_data(gs);
	gs->buf = buf;
	gs->size = size;

	return 0;
}

static int is_empty_line(const char *bol, const char *eol)
{
	while (bol < eol && isspace(*bol))
		bol++;
	return bol == eol;
}

static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int collect_hits)
{
	char *bol;
	char *peek_bol = NULL;
	unsigned long left;
	unsigned lno = 1;
	unsigned last_hit = 0;
	int binary_match_only = 0;
	unsigned count = 0;
	int try_lookahead = 0;
	int show_function = 0;
	struct userdiff_driver *textconv = NULL;
	enum grep_context ctx = GREP_CONTEXT_HEAD;
	xdemitconf_t xecfg;

	if (!opt->status_only && gs->name == NULL)
		BUG("grep call which could print a name requires "
		    "grep_source.name be non-NULL");

	if (!opt->output)
		opt->output = std_output;

	if (opt->pre_context || opt->post_context || opt->file_break ||
	    opt->funcbody) {
		/* Show hunk marks, except for the first file. */
		if (opt->last_shown)
			opt->show_hunk_mark = 1;
		/*
		 * If we're using threads then we can't easily identify
		 * the first file.  Always put hunk marks in that case
		 * and skip the very first one later in work_done().
		 */
		if (opt->output != std_output)
			opt->show_hunk_mark = 1;
	}
	opt->last_shown = 0;

	if (opt->allow_textconv) {
		grep_source_load_driver(gs, opt->repo->index);
		/*
		 * We might set up the shared textconv cache data here, which
		 * is not thread-safe. Also, get_oid_with_context() and
		 * parse_object() might be internally called. As they are not
		 * currenty thread-safe and might be racy with object reading,
		 * obj_read_lock() must be called.
		 */
		grep_attr_lock();
		obj_read_lock();
		textconv = userdiff_get_textconv(opt->repo, gs->driver);
		obj_read_unlock();
		grep_attr_unlock();
	}

	/*
	 * We know the result of a textconv is text, so we only have to care
	 * about binary handling if we are not using it.
	 */
	if (!textconv) {
		switch (opt->binary) {
		case GREP_BINARY_DEFAULT:
			if (grep_source_is_binary(gs, opt->repo->index))
				binary_match_only = 1;
			break;
		case GREP_BINARY_NOMATCH:
			if (grep_source_is_binary(gs, opt->repo->index))
				return 0; /* Assume unmatch */
			break;
		case GREP_BINARY_TEXT:
			break;
		default:
			BUG("unknown binary handling mode");
		}
	}

	memset(&xecfg, 0, sizeof(xecfg));
	opt->priv = &xecfg;

	try_lookahead = should_lookahead(opt);

	if (fill_textconv_grep(opt->repo, textconv, gs) < 0)
		return 0;

	bol = gs->buf;
	left = gs->size;
	while (left) {
		char *eol, ch;
		int hit;
		ssize_t cno;
		ssize_t col = -1, icol = -1;

		/*
		 * look_ahead() skips quickly to the line that possibly
		 * has the next hit; don't call it if we need to do
		 * something more than just skipping the current line
		 * in response to an unmatch for the current line.  E.g.
		 * inside a post-context window, we will show the current
		 * line as a context around the previous hit when it
		 * doesn't hit.
		 */
		if (try_lookahead
		    && !(last_hit
			 && (show_function ||
			     lno <= last_hit + opt->post_context))
		    && look_ahead(opt, &left, &lno, &bol))
			break;
		eol = end_of_line(bol, &left);
		ch = *eol;
		*eol = 0;

		if ((ctx == GREP_CONTEXT_HEAD) && (eol == bol))
			ctx = GREP_CONTEXT_BODY;

		hit = match_line(opt, bol, eol, &col, &icol, ctx, collect_hits);
		*eol = ch;

		if (collect_hits)
			goto next_line;

		/* "grep -v -e foo -e bla" should list lines
		 * that do not have either, so inversion should
		 * be done outside.
		 */
		if (opt->invert)
			hit = !hit;
		if (opt->unmatch_name_only) {
			if (hit)
				return 0;
			goto next_line;
		}
		if (hit) {
			count++;
			if (opt->status_only)
				return 1;
			if (opt->name_only) {
				show_name(opt, gs->name);
				return 1;
			}
			if (opt->count)
				goto next_line;
			if (binary_match_only) {
				opt->output(opt, "Binary file ", 12);
				output_color(opt, gs->name, strlen(gs->name),
					     opt->colors[GREP_COLOR_FILENAME]);
				opt->output(opt, " matches\n", 9);
				return 1;
			}
			/* Hit at this line.  If we haven't shown the
			 * pre-context lines, we would need to show them.
			 */
			if (opt->pre_context || opt->funcbody)
				show_pre_context(opt, gs, bol, eol, lno);
			else if (opt->funcname)
				show_funcname_line(opt, gs, bol, lno);
			cno = opt->invert ? icol : col;
			if (cno < 0) {
				/*
				 * A negative cno indicates that there was no
				 * match on the line. We are thus inverted and
				 * being asked to show all lines that _don't_
				 * match a given expression. Therefore, set cno
				 * to 0 to suggest the whole line matches.
				 */
				cno = 0;
			}
			show_line(opt, bol, eol, gs->name, lno, cno + 1, ':');
			last_hit = lno;
			if (opt->funcbody)
				show_function = 1;
			goto next_line;
		}
		if (show_function && (!peek_bol || peek_bol < bol)) {
			unsigned long peek_left = left;
			char *peek_eol = eol;

			/*
			 * Trailing empty lines are not interesting.
			 * Peek past them to see if they belong to the
			 * body of the current function.
			 */
			peek_bol = bol;
			while (is_empty_line(peek_bol, peek_eol)) {
				peek_bol = peek_eol + 1;
				peek_eol = end_of_line(peek_bol, &peek_left);
			}

			if (match_funcname(opt, gs, peek_bol, peek_eol))
				show_function = 0;
		}
		if (show_function ||
		    (last_hit && lno <= last_hit + opt->post_context)) {
			/* If the last hit is within the post context,
			 * we need to show this line.
			 */
			show_line(opt, bol, eol, gs->name, lno, col + 1, '-');
		}

	next_line:
		bol = eol + 1;
		if (!left)
			break;
		left--;
		lno++;
	}

	if (collect_hits)
		return 0;

	if (opt->status_only)
		return opt->unmatch_name_only;
	if (opt->unmatch_name_only) {
		/* We did not see any hit, so we want to show this */
		show_name(opt, gs->name);
		return 1;
	}

	xdiff_clear_find_func(&xecfg);
	opt->priv = NULL;

	/* NEEDSWORK:
	 * The real "grep -c foo *.c" gives many "bar.c:0" lines,
	 * which feels mostly useless but sometimes useful.  Maybe
	 * make it another option?  For now suppress them.
	 */
	if (opt->count && count) {
		char buf[32];
		if (opt->pathname) {
			output_color(opt, gs->name, strlen(gs->name),
				     opt->colors[GREP_COLOR_FILENAME]);
			output_sep(opt, ':');
		}
		xsnprintf(buf, sizeof(buf), "%u\n", count);
		opt->output(opt, buf, strlen(buf));
		return 1;
	}
	return !!last_hit;
}

static void clr_hit_marker(struct grep_expr *x)
{
	/* All-hit markers are meaningful only at the very top level
	 * OR node.
	 */
	while (1) {
		x->hit = 0;
		if (x->node != GREP_NODE_OR)
			return;
		x->u.binary.left->hit = 0;
		x = x->u.binary.right;
	}
}

static int chk_hit_marker(struct grep_expr *x)
{
	/* Top level nodes have hit markers.  See if they all are hits */
	while (1) {
		if (x->node != GREP_NODE_OR)
			return x->hit;
		if (!x->u.binary.left->hit)
			return 0;
		x = x->u.binary.right;
	}
}

int grep_source(struct grep_opt *opt, struct grep_source *gs)
{
	/*
	 * we do not have to do the two-pass grep when we do not check
	 * buffer-wide "all-match".
	 */
	if (!opt->all_match)
		return grep_source_1(opt, gs, 0);

	/* Otherwise the toplevel "or" terms hit a bit differently.
	 * We first clear hit markers from them.
	 */
	clr_hit_marker(opt->pattern_expression);
	grep_source_1(opt, gs, 1);

	if (!chk_hit_marker(opt->pattern_expression))
		return 0;

	return grep_source_1(opt, gs, 0);
}

int grep_buffer(struct grep_opt *opt, char *buf, unsigned long size)
{
	struct grep_source gs;
	int r;

	grep_source_init(&gs, GREP_SOURCE_BUF, NULL, NULL, NULL);
	gs.buf = buf;
	gs.size = size;

	r = grep_source(opt, &gs);

	grep_source_clear(&gs);
	return r;
}

void grep_source_init(struct grep_source *gs, enum grep_source_type type,
		      const char *name, const char *path,
		      const void *identifier)
{
	gs->type = type;
	gs->name = xstrdup_or_null(name);
	gs->path = xstrdup_or_null(path);
	gs->buf = NULL;
	gs->size = 0;
	gs->driver = NULL;

	switch (type) {
	case GREP_SOURCE_FILE:
		gs->identifier = xstrdup(identifier);
		break;
	case GREP_SOURCE_OID:
		gs->identifier = oiddup(identifier);
		break;
	case GREP_SOURCE_BUF:
		gs->identifier = NULL;
		break;
	}
}

void grep_source_clear(struct grep_source *gs)
{
	FREE_AND_NULL(gs->name);
	FREE_AND_NULL(gs->path);
	FREE_AND_NULL(gs->identifier);
	grep_source_clear_data(gs);
}

void grep_source_clear_data(struct grep_source *gs)
{
	switch (gs->type) {
	case GREP_SOURCE_FILE:
	case GREP_SOURCE_OID:
		FREE_AND_NULL(gs->buf);
		gs->size = 0;
		break;
	case GREP_SOURCE_BUF:
		/* leave user-provided buf intact */
		break;
	}
}

static int grep_source_load_oid(struct grep_source *gs)
{
	enum object_type type;

	gs->buf = read_object_file(gs->identifier, &type, &gs->size);
	if (!gs->buf)
		return error(_("'%s': unable to read %s"),
			     gs->name,
			     oid_to_hex(gs->identifier));
	return 0;
}

static int grep_source_load_file(struct grep_source *gs)
{
	const char *filename = gs->identifier;
	struct stat st;
	char *data;
	size_t size;
	int i;

	if (lstat(filename, &st) < 0) {
	err_ret:
		if (errno != ENOENT)
			error_errno(_("failed to stat '%s'"), filename);
		return -1;
	}
	if (!S_ISREG(st.st_mode))
		return -1;
	size = xsize_t(st.st_size);
	i = open(filename, O_RDONLY);
	if (i < 0)
		goto err_ret;
	data = xmallocz(size);
	if (st.st_size != read_in_full(i, data, size)) {
		error_errno(_("'%s': short read"), filename);
		close(i);
		free(data);
		return -1;
	}
	close(i);

	gs->buf = data;
	gs->size = size;
	return 0;
}

static int grep_source_load(struct grep_source *gs)
{
	if (gs->buf)
		return 0;

	switch (gs->type) {
	case GREP_SOURCE_FILE:
		return grep_source_load_file(gs);
	case GREP_SOURCE_OID:
		return grep_source_load_oid(gs);
	case GREP_SOURCE_BUF:
		return gs->buf ? 0 : -1;
	}
	BUG("invalid grep_source type to load");
}

void grep_source_load_driver(struct grep_source *gs,
			     struct index_state *istate)
{
	if (gs->driver)
		return;

	grep_attr_lock();
	if (gs->path)
		gs->driver = userdiff_find_by_path(istate, gs->path);
	if (!gs->driver)
		gs->driver = userdiff_find_by_name("default");
	grep_attr_unlock();
}

static int grep_source_is_binary(struct grep_source *gs,
				 struct index_state *istate)
{
	grep_source_load_driver(gs, istate);
	if (gs->driver->binary != -1)
		return gs->driver->binary;

	if (!grep_source_load(gs))
		return buffer_is_binary(gs->buf, gs->size);

	return 0;
}