Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 2198 insertions, 0 deletions

diff --git a/grep.c b/grep.c
new file mode 100644
index 000000000000..cd952ef5d3cc
--- /dev/null
+++ b/grep.c
@@ -0,0 +1,2198 @@
+#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;
+
+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).
+ */
+void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
+{
+	struct grep_opt *def = &grep_defaults;
+	int i;
+
+	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]);
+}
+
+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;
+}
+
+static int has_null(const char *s, size_t len)
+{
+	/*
+	 * regcomp cannot accept patterns with NULs so when using it
+	 * we consider any pattern containing a NUL fixed.
+	 */
+	if (memchr(s, 0, len))
+		return 1;
+
+	return 0;
+}
+
+#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;
+
+	if (opt->ignore_case) {
+		if (has_non_ascii(p->pattern))
+			p->pcre1_tables = pcre_maketables();
+		options |= PCRE_CASELESS;
+	}
+	if (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);
+
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, GIT_PCRE_STUDY_JIT_COMPILE, &error);
+	if (!p->pcre1_extra_info && error)
+		die("%s", error);
+
+#ifdef GIT_PCRE1_USE_JIT
+	pcre_config(PCRE_CONFIG_JIT, &p->pcre1_jit_on);
+	if (p->pcre1_jit_on == 1) {
+		p->pcre1_jit_stack = pcre_jit_stack_alloc(1, 1024 * 1024);
+		if (!p->pcre1_jit_stack)
+			die("Couldn't allocate PCRE JIT stack");
+		pcre_assign_jit_stack(p->pcre1_extra_info, NULL, p->pcre1_jit_stack);
+	} else if (p->pcre1_jit_on != 0) {
+		BUG("The pcre1_jit_on variable should be 0 or 1, not %d",
+		    p->pcre1_jit_on);
+	}
+#endif
+}
+
+static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
+		regmatch_t *match, int eflags)
+{
+	int ovector[30], ret, flags = 0;
+
+	if (eflags & REG_NOTBOL)
+		flags |= PCRE_NOTBOL;
+
+#ifdef GIT_PCRE1_USE_JIT
+	if (p->pcre1_jit_on) {
+		ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
+				    eol - line, 0, flags, ovector,
+				    ARRAY_SIZE(ovector), p->pcre1_jit_stack);
+	} else
+#endif
+	{
+		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 GIT_PCRE1_USE_JIT
+	if (p->pcre1_jit_on) {
+		pcre_free_study(p->pcre1_extra_info);
+		pcre_jit_stack_free(p->pcre1_jit_stack);
+	} 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;
+	const uint8_t *character_tables = NULL;
+	int jitret;
+	int patinforet;
+	size_t jitsizearg;
+
+	assert(opt->pcre2);
+
+	p->pcre2_compile_context = NULL;
+
+	if (opt->ignore_case) {
+		if (has_non_ascii(p->pattern)) {
+			character_tables = pcre2_maketables(NULL);
+			p->pcre2_compile_context = pcre2_compile_context_create(NULL);
+			pcre2_set_character_tables(p->pcre2_compile_context, character_tables);
+		}
+		options |= PCRE2_CASELESS;
+	}
+	if (is_utf8_locale() && has_non_ascii(p->pattern))
+		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 (p->pcre2_jit_on == 1) {
+		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;
+			return;
+		}
+
+		p->pcre2_jit_stack = pcre2_jit_stack_create(1, 1024 * 1024, NULL);
+		if (!p->pcre2_jit_stack)
+			die("Couldn't allocate PCRE2 JIT stack");
+		p->pcre2_match_context = pcre2_match_context_create(NULL);
+		if (!p->pcre2_match_context)
+			die("Couldn't allocate PCRE2 match context");
+		pcre2_jit_stack_assign(p->pcre2_match_context, NULL, p->pcre2_jit_stack);
+	} else if (p->pcre2_jit_on != 0) {
+		BUG("The pcre2_jit_on variable should be 0 or 1, not %d",
+		    p->pcre2_jit_on);
+	}
+}
+
+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);
+	pcre2_jit_stack_free(p->pcre2_jit_stack);
+	pcre2_match_context_free(p->pcre2_match_context);
+}
+#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)
+{
+}
+#endif /* !USE_LIBPCRE2 */
+
+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);
+	}
+}
+
+static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
+{
+	int ascii_only;
+	int err;
+	int regflags = REG_NEWLINE;
+
+	p->word_regexp = opt->word_regexp;
+	p->ignore_case = opt->ignore_case;
+	ascii_only     = !has_non_ascii(p->pattern);
+
+	/*
+	 * Even when -F (fixed) asks us to do a non-regexp search, we
+	 * may not be able to correctly case-fold when -i
+	 * (ignore-case) is asked (in which case, we'll synthesize a
+	 * regexp to match the pattern that matches regexp special
+	 * characters literally, while ignoring case differences).  On
+	 * the other hand, even without -F, if the pattern does not
+	 * have any regexp special characters and there is no need for
+	 * case-folding search, we can internally turn it into a
+	 * simple string match using kws.  p->fixed tells us if we
+	 * want to use kws.
+	 */
+	if (opt->fixed ||
+	    has_null(p->pattern, p->patternlen) ||
+	    is_fixed(p->pattern, p->patternlen))
+		p->fixed = !p->ignore_case || ascii_only;
+
+	if (p->fixed) {
+		p->kws = kwsalloc(p->ignore_case ? tolower_trans_tbl : NULL);
+		kwsincr(p->kws, p->pattern, p->patternlen);
+		kwsprep(p->kws);
+		return;
+	} else if (opt->fixed) {
+		/*
+		 * We come here when the pattern has the non-ascii
+		 * characters we cannot case-fold, and asked to
+		 * ignore-case.
+		 */
+		compile_fixed_regexp(p, opt);
+		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->kws)
+				kwsfree(p->kws);
+			else 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 fixmatch(struct grep_pat *p, char *line, char *eol,
+		    regmatch_t *match)
+{
+	struct kwsmatch kwsm;
+	size_t offset = kwsexec(p->kws, line, eol - line, &kwsm);
+	if (offset == -1) {
+		match->rm_so = match->rm_eo = -1;
+		return REG_NOMATCH;
+	} else {
+		match->rm_so = offset;
+		match->rm_eo = match->rm_so + kwsm.size[0];
+		return 0;
+	}
+}
+
+static int patmatch(struct grep_pat *p, char *line, char *eol,
+		    regmatch_t *match, int eflags)
+{
+	int hit;
+
+	if (p->fixed)
+		hit = !fixmatch(p, line, eol, match);
+	else 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);
+}
+
+/*
+ * Same as git_attr_mutex, but protecting the thread-unsafe object db access.
+ */
+pthread_mutex_t grep_read_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 may load objects
+	 * behind the scenes, and it modifies the global diff tempfile
+	 * structure.
+	 */
+	grep_read_lock();
+	size = fill_textconv(r, driver, df, &buf);
+	grep_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.
+		 */
+		grep_attr_lock();
+		textconv = userdiff_get_textconv(opt->repo, gs->driver);
+		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;
+
+	grep_read_lock();
+	gs->buf = read_object_file(gs->identifier, &type, &gs->size);
+	grep_read_unlock();
+
+	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;
+}