Merge branch 'jc/grep-lookahead'

* jc/grep-lookahead:
  grep --no-index: allow use of "git grep" outside a git repository
  grep: prepare to run outside of a work tree
  grep: rip out pessimization to use fixmatch()
  grep: rip out support for external grep
  grep: optimize built-in grep by skipping lines that do not hit

Conflicts:
	builtin-grep.c
	t/t7002-grep.sh

7 files changed, 166 insertions, 370 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 76c7d9c7e..d40b83f85 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -664,14 +664,6 @@ color.grep::
 	`never`), never.  When set to `true` or `auto`, use color only
 	when the output is written to the terminal.  Defaults to `false`.
 
-color.grep.external::
-	The string value of this variable is passed to an external 'grep'
-	command as a command line option if match highlighting is turned
-	on.  If set to an empty string, no option is passed at all,
-	turning off coloring for external 'grep' calls; this is the default.
-	For GNU grep, set it to `--color=always` to highlight matches even
-	when a pager is used.
-
 color.grep.match::
 	Use customized color for matches.  The value of this variable
 	may be specified as in color.branch.<slot>.  It is passed using
diff --git a/Makefile b/Makefile
index b7f56b7ea..d74c19623 100644
--- a/Makefile
+++ b/Makefile
@@ -187,10 +187,6 @@ all::
 # is a simplified version of the merge sort used in glibc. This is
 # recommended if Git triggers O(n^2) behavior in your platform's qsort().
 #
-# Define NO_EXTERNAL_GREP if you don't want "git grep" to ever call
-# your external grep (e.g., if your system lacks grep, if its grep is
-# broken, or spawning external process is slower than built-in grep git has).
-#
 # Define UNRELIABLE_FSTAT if your system's fstat does not return the same
 # information on a not yet closed file that lstat would return for the same
 # file after it was closed.
@@ -795,7 +791,6 @@ ifeq ($(uname_S),SunOS)
 	NO_MKDTEMP = YesPlease
 	NO_MKSTEMPS = YesPlease
 	NO_REGEX = YesPlease
-	NO_EXTERNAL_GREP = YesPlease
 	THREADED_DELTA_SEARCH = YesPlease
 	ifeq ($(uname_R),5.7)
 		NEEDS_RESOLV = YesPlease
@@ -914,7 +909,6 @@ ifeq ($(uname_S),IRIX)
 	# NO_MMAP.  If you suspect that your compiler is not affected by this
 	# issue, comment out the NO_MMAP statement.
 	NO_MMAP = YesPlease
-	NO_EXTERNAL_GREP = UnfortunatelyYes
 	SNPRINTF_RETURNS_BOGUS = YesPlease
 	SHELL_PATH = /usr/gnu/bin/bash
 	NEEDS_LIBGEN = YesPlease
@@ -934,7 +928,6 @@ ifeq ($(uname_S),IRIX64)
 	# NO_MMAP.  If you suspect that your compiler is not affected by this
 	# issue, comment out the NO_MMAP statement.
 	NO_MMAP = YesPlease
-	NO_EXTERNAL_GREP = UnfortunatelyYes
 	SNPRINTF_RETURNS_BOGUS = YesPlease
 	SHELL_PATH=/usr/gnu/bin/bash
 	NEEDS_LIBGEN = YesPlease
@@ -1349,9 +1342,6 @@ endif
 ifdef DIR_HAS_BSD_GROUP_SEMANTICS
 	COMPAT_CFLAGS += -DDIR_HAS_BSD_GROUP_SEMANTICS
 endif
-ifdef NO_EXTERNAL_GREP
-	BASIC_CFLAGS += -DNO_EXTERNAL_GREP
-endif
 ifdef UNRELIABLE_FSTAT
 	BASIC_CFLAGS += -DUNRELIABLE_FSTAT
 endif
diff --git a/builtin-grep.c b/builtin-grep.c
index cea973ba6..da854fa94 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -14,14 +14,7 @@
 #include "userdiff.h"
 #include "grep.h"
 #include "quote.h"
-
-#ifndef NO_EXTERNAL_GREP
-#ifdef __unix__
-#define NO_EXTERNAL_GREP 0
-#else
-#define NO_EXTERNAL_GREP 1
-#endif
-#endif
+#include "dir.h"
 
 static char const * const grep_usage[] = {
 	"git grep [options] [-e] <pattern> [<rev>...] [[--] path...]",
@@ -42,8 +35,6 @@ static int grep_config(const char *var, const char *value, void *cb)
 		opt->color = git_config_colorbool(var, value, -1);
 		return 0;
 	}
-	if (!strcmp(var, "color.grep.external"))
-		return git_config_string(&(opt->color_external), var, value);
 	if (!strcmp(var, "color.grep.match")) {
 		if (!value)
 			return config_error_nonbool(var);
@@ -214,309 +205,12 @@ static int grep_file(struct grep_opt *opt, const char *filename)
 	return i;
 }
 
-#if !NO_EXTERNAL_GREP
-static int exec_grep(int argc, const char **argv)
-{
-	pid_t pid;
-	int status;
-
-	argv[argc] = NULL;
-	trace_argv_printf(argv, "trace: grep:");
-	pid = fork();
-	if (pid < 0)
-		return pid;
-	if (!pid) {
-		execvp("grep", (char **) argv);
-		exit(255);
-	}
-	while (waitpid(pid, &status, 0) < 0) {
-		if (errno == EINTR)
-			continue;
-		return -1;
-	}
-	if (WIFEXITED(status)) {
-		if (!WEXITSTATUS(status))
-			return 1;
-		return 0;
-	}
-	return -1;
-}
-
-#define MAXARGS 1000
-#define ARGBUF 4096
-#define push_arg(a) do { \
-	if (nr < MAXARGS) argv[nr++] = (a); \
-	else die("maximum number of args exceeded"); \
-	} while (0)
-
-/*
- * If you send a singleton filename to grep, it does not give
- * the name of the file.  GNU grep has "-H" but we would want
- * that behaviour in a portable way.
- *
- * So we keep two pathnames in argv buffer unsent to grep in
- * the main loop if we need to do more than one grep.
- */
-static int flush_grep(struct grep_opt *opt,
-		      int argc, int arg0, const char **argv, int *kept)
-{
-	int status;
-	int count = argc - arg0;
-	const char *kept_0 = NULL;
-
-	if (count <= 2) {
-		/*
-		 * Because we keep at least 2 paths in the call from
-		 * the main loop (i.e. kept != NULL), and MAXARGS is
-		 * far greater than 2, this usually is a call to
-		 * conclude the grep.  However, the user could attempt
-		 * to overflow the argv buffer by giving too many
-		 * options to leave very small number of real
-		 * arguments even for the call in the main loop.
-		 */
-		if (kept)
-			die("insanely many options to grep");
-
-		/*
-		 * If we have two or more paths, we do not have to do
-		 * anything special, but we need to push /dev/null to
-		 * get "-H" behaviour of GNU grep portably but when we
-		 * are not doing "-l" nor "-L" nor "-c".
-		 */
-		if (count == 1 &&
-		    !opt->name_only &&
-		    !opt->unmatch_name_only &&
-		    !opt->count) {
-			argv[argc++] = "/dev/null";
-			argv[argc] = NULL;
-		}
-	}
-
-	else if (kept) {
-		/*
-		 * Called because we found many paths and haven't finished
-		 * iterating over the cache yet.  We keep two paths
-		 * for the concluding call.  argv[argc-2] and argv[argc-1]
-		 * has the last two paths, so save the first one away,
-		 * replace it with NULL while sending the list to grep,
-		 * and recover them after we are done.
-		 */
-		*kept = 2;
-		kept_0 = argv[argc-2];
-		argv[argc-2] = NULL;
-		argc -= 2;
-	}
-
-	if (opt->pre_context || opt->post_context) {
-		/*
-		 * grep handles hunk marks between files, but we need to
-		 * do that ourselves between multiple calls.
-		 */
-		if (opt->show_hunk_mark)
-			write_or_die(1, "--\n", 3);
-		else
-			opt->show_hunk_mark = 1;
-	}
-
-	status = exec_grep(argc, argv);
-
-	if (kept_0) {
-		/*
-		 * Then recover them.  Now the last arg is beyond the
-		 * terminating NULL which is at argc, and the second
-		 * from the last is what we saved away in kept_0
-		 */
-		argv[arg0++] = kept_0;
-		argv[arg0] = argv[argc+1];
-	}
-	return status;
-}
-
-static void grep_add_color(struct strbuf *sb, const char *escape_seq)
-{
-	size_t orig_len = sb->len;
-
-	while (*escape_seq) {
-		if (*escape_seq == 'm')
-			strbuf_addch(sb, ';');
-		else if (*escape_seq != '\033' && *escape_seq  != '[')
-			strbuf_addch(sb, *escape_seq);
-		escape_seq++;
-	}
-	if (sb->len > orig_len && sb->buf[sb->len - 1] == ';')
-		strbuf_setlen(sb, sb->len - 1);
-}
-
-static int has_skip_worktree_entry(struct grep_opt *opt, const char **paths)
-{
-	int nr;
-	for (nr = 0; nr < active_nr; nr++) {
-		struct cache_entry *ce = active_cache[nr];
-		if (!S_ISREG(ce->ce_mode))
-			continue;
-		if (!pathspec_matches(paths, ce->name, opt->max_depth))
-			continue;
-		if (ce_skip_worktree(ce))
-			return 1;
-	}
-	return 0;
-}
-
-static int external_grep(struct grep_opt *opt, const char **paths, int cached)
-{
-	int i, nr, argc, hit, len, status;
-	const char *argv[MAXARGS+1];
-	char randarg[ARGBUF];
-	char *argptr = randarg;
-	struct grep_pat *p;
-
-	if (opt->extended || (opt->relative && opt->prefix_length)
-	    || has_skip_worktree_entry(opt, paths))
-		return -1;
-	len = nr = 0;
-	push_arg("grep");
-	if (opt->fixed)
-		push_arg("-F");
-	if (opt->linenum)
-		push_arg("-n");
-	if (!opt->pathname)
-		push_arg("-h");
-	if (opt->regflags & REG_EXTENDED)
-		push_arg("-E");
-	if (opt->ignore_case)
-		push_arg("-i");
-	if (opt->binary == GREP_BINARY_NOMATCH)
-		push_arg("-I");
-	if (opt->word_regexp)
-		push_arg("-w");
-	if (opt->name_only)
-		push_arg("-l");
-	if (opt->unmatch_name_only)
-		push_arg("-L");
-	if (opt->null_following_name)
-		/* in GNU grep git's "-z" translates to "-Z" */
-		push_arg("-Z");
-	if (opt->count)
-		push_arg("-c");
-	if (opt->post_context || opt->pre_context) {
-		if (opt->post_context != opt->pre_context) {
-			if (opt->pre_context) {
-				push_arg("-B");
-				len += snprintf(argptr, sizeof(randarg)-len,
-						"%u", opt->pre_context) + 1;
-				if (sizeof(randarg) <= len)
-					die("maximum length of args exceeded");
-				push_arg(argptr);
-				argptr += len;
-			}
-			if (opt->post_context) {
-				push_arg("-A");
-				len += snprintf(argptr, sizeof(randarg)-len,
-						"%u", opt->post_context) + 1;
-				if (sizeof(randarg) <= len)
-					die("maximum length of args exceeded");
-				push_arg(argptr);
-				argptr += len;
-			}
-		}
-		else {
-			push_arg("-C");
-			len += snprintf(argptr, sizeof(randarg)-len,
-					"%u", opt->post_context) + 1;
-			if (sizeof(randarg) <= len)
-				die("maximum length of args exceeded");
-			push_arg(argptr);
-			argptr += len;
-		}
-	}
-	for (p = opt->pattern_list; p; p = p->next) {
-		push_arg("-e");
-		push_arg(p->pattern);
-	}
-	if (opt->color) {
-		struct strbuf sb = STRBUF_INIT;
-
-		grep_add_color(&sb, opt->color_match);
-		setenv("GREP_COLOR", sb.buf, 1);
-
-		strbuf_reset(&sb);
-		strbuf_addstr(&sb, "mt=");
-		grep_add_color(&sb, opt->color_match);
-		strbuf_addstr(&sb, ":sl=:cx=:fn=:ln=:bn=:se=");
-		setenv("GREP_COLORS", sb.buf, 1);
-
-		strbuf_release(&sb);
-
-		if (opt->color_external && strlen(opt->color_external) > 0)
-			push_arg(opt->color_external);
-	} else {
-		unsetenv("GREP_COLOR");
-		unsetenv("GREP_COLORS");
-	}
-	unsetenv("GREP_OPTIONS");
-
-	hit = 0;
-	argc = nr;
-	for (i = 0; i < active_nr; i++) {
-		struct cache_entry *ce = active_cache[i];
-		char *name;
-		int kept;
-		if (!S_ISREG(ce->ce_mode))
-			continue;
-		if (!pathspec_matches(paths, ce->name, opt->max_depth))
-			continue;
-		name = ce->name;
-		if (name[0] == '-') {
-			int len = ce_namelen(ce);
-			name = xmalloc(len + 3);
-			memcpy(name, "./", 2);
-			memcpy(name + 2, ce->name, len + 1);
-		}
-		argv[argc++] = name;
-		if (MAXARGS <= argc) {
-			status = flush_grep(opt, argc, nr, argv, &kept);
-			if (0 < status)
-				hit = 1;
-			argc = nr + kept;
-		}
-		if (ce_stage(ce)) {
-			do {
-				i++;
-			} while (i < active_nr &&
-				 !strcmp(ce->name, active_cache[i]->name));
-			i--; /* compensate for loop control */
-		}
-	}
-	if (argc > nr) {
-		status = flush_grep(opt, argc, nr, argv, NULL);
-		if (0 < status)
-			hit = 1;
-	}
-	return hit;
-}
-#endif
-
-static int grep_cache(struct grep_opt *opt, const char **paths, int cached,
-		      int external_grep_allowed)
+static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 {
 	int hit = 0;
 	int nr;
 	read_cache();
 
-#if !NO_EXTERNAL_GREP
-	/*
-	 * Use the external "grep" command for the case where
-	 * we grep through the checked-out files. It tends to
-	 * be a lot more optimized
-	 */
-	if (!cached && external_grep_allowed) {
-		hit = external_grep(opt, paths, cached);
-		if (hit >= 0)
-			return hit;
-		hit = 0;
-	}
-#endif
-
 	for (nr = 0; nr < active_nr; nr++) {
 		struct cache_entry *ce = active_cache[nr];
 		if (!S_ISREG(ce->ce_mode))
@@ -626,6 +320,21 @@ static int grep_object(struct grep_opt *opt, const char **paths,
 	die("unable to grep from object of type %s", typename(obj->type));
 }
 
+static int grep_directory(struct grep_opt *opt, const char **paths)
+{
+	struct dir_struct dir;
+	int i, hit = 0;
+
+	memset(&dir, 0, sizeof(dir));
+	setup_standard_excludes(&dir);
+
+	fill_directory(&dir, paths);
+	for (i = 0; i < dir.nr; i++)
+		hit |= grep_file(opt, dir.entries[i]->name);
+	free_grep_patterns(opt);
+	return hit;
+}
+
 static int context_callback(const struct option *opt, const char *arg,
 			    int unset)
 {
@@ -713,16 +422,19 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 {
 	int hit = 0;
 	int cached = 0;
-	int external_grep_allowed = 1;
 	int seen_dashdash = 0;
+	int external_grep_allowed__ignored;
 	struct grep_opt opt;
 	struct object_array list = { 0, 0, NULL };
 	const char **paths = NULL;
 	int i;
 	int dummy;
+	int nongit = 0, use_index = 1;
 	struct option options[] = {
 		OPT_BOOLEAN(0, "cached", &cached,
 			"search in index instead of in the work tree"),
+		OPT_BOOLEAN(0, "index", &use_index,
+			"--no-index finds in contents not managed by git"),
 		OPT_GROUP(""),
 		OPT_BOOLEAN('v', "invert-match", &opt.invert,
 			"show non-matching lines"),
@@ -796,18 +508,15 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		OPT_BOOLEAN(0, "all-match", &opt.all_match,
 			"show only matches from files that match all patterns"),
 		OPT_GROUP(""),
-#if NO_EXTERNAL_GREP
-		OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed,
-			"allow calling of grep(1) (ignored by this build)"),
-#else
-		OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed,
-			"allow calling of grep(1) (default)"),
-#endif
+		OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed__ignored,
+			    "allow calling of grep(1) (ignored by this build)"),
 		{ OPTION_CALLBACK, 0, "help-all", &options, NULL, "show usage",
 		  PARSE_OPT_HIDDEN | PARSE_OPT_NOARG, help_callback },
 		OPT_END()
 	};
 
+	prefix = setup_git_directory_gently(&nongit);
+
 	/*
 	 * 'git grep -h', unlike 'git grep -h <pattern>', is a request
 	 * to show usage information and exit.
@@ -845,6 +554,10 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			     PARSE_OPT_STOP_AT_NON_OPTION |
 			     PARSE_OPT_NO_INTERNAL_HELP);
 
+	if (use_index && nongit)
+		/* die the same way as if we did it at the beginning */
+		setup_git_directory();
+
 	/* First unrecognized non-option token */
 	if (argc > 0 && !opt.pattern_list) {
 		append_grep_pattern(&opt, argv[0], "command line", 0,
@@ -853,8 +566,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		argc--;
 	}
 
-	if ((opt.color && !opt.color_external) || opt.funcname)
-		external_grep_allowed = 0;
 	if (!opt.pattern_list)
 		die("no pattern given.");
 	if (!opt.fixed && opt.ignore_case)
@@ -897,10 +608,18 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		paths[1] = NULL;
 	}
 
+	if (!use_index) {
+		if (cached)
+			die("--cached cannot be used with --no-index.");
+		if (list.nr)
+			die("--no-index cannot be used with revs.");
+		return !grep_directory(&opt, paths);
+	}
+
 	if (!list.nr) {
 		if (!cached)
 			setup_work_tree();
-		return !grep_cache(&opt, paths, cached, external_grep_allowed);
+		return !grep_cache(&opt, paths, cached);
 	}
 
 	if (cached)
diff --git a/git.c b/git.c
index 11544cdb4..ad074735f 100644
--- a/git.c
+++ b/git.c
@@ -317,7 +317,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "fsck-objects", cmd_fsck, RUN_SETUP },
 		{ "gc", cmd_gc, RUN_SETUP },
 		{ "get-tar-commit-id", cmd_get_tar_commit_id },
-		{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
+		{ "grep", cmd_grep, USE_PAGER },
 		{ "help", cmd_help },
 		{ "init", cmd_init_db },
 		{ "init-db", cmd_init_db },
diff --git a/grep.c b/grep.c
index bdadf2c0c..8e1f7de77 100644
--- a/grep.c
+++ b/grep.c
@@ -29,13 +29,6 @@ void append_grep_pattern(struct grep_opt *opt, const char *pat,
 	p->next = NULL;
 }
 
-static int is_fixed(const char *s)
-{
-	while (*s && !is_regex_special(*s))
-		s++;
-	return !*s;
-}
-
 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	int err;
@@ -43,7 +36,7 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 	p->word_regexp = opt->word_regexp;
 	p->ignore_case = opt->ignore_case;
 
-	if (opt->fixed || is_fixed(p->pattern))
+	if (opt->fixed)
 		p->fixed = 1;
 	if (opt->regflags & REG_ICASE)
 		p->fixed = 0;
@@ -615,6 +608,65 @@ static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
 	}
 }
 
+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;
+
+		if (p->fixed)
+			hit = !fixmatch(p->pattern, bol, p->ignore_case, &m);
+		else
+			hit = !regexec(&p->regexp, bol, 1, &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 grep_buffer_1(struct grep_opt *opt, const char *name,
 			 char *buf, unsigned long size, int collect_hits)
 {
@@ -624,6 +676,7 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 	unsigned last_hit = 0;
 	int binary_match_only = 0;
 	unsigned count = 0;
+	int try_lookahead = 0;
 	enum grep_context ctx = GREP_CONTEXT_HEAD;
 	xdemitconf_t xecfg;
 
@@ -652,11 +705,26 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			opt->priv = &xecfg;
 		}
 	}
+	try_lookahead = should_lookahead(opt);
 
 	while (left) {
 		char *eol, ch;
 		int hit;
 
+		/*
+		 * look_ahead() skips quicly 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
+			 && lno <= last_hit + opt->post_context)
+		    && look_ahead(opt, &left, &lno, &bol))
+			break;
 		eol = end_of_line(bol, &left);
 		ch = *eol;
 		*eol = 0;
diff --git a/grep.h b/grep.h
index 75370f60d..0c61b00cb 100644
--- a/grep.h
+++ b/grep.h
@@ -85,7 +85,6 @@ struct grep_opt {
 	int max_depth;
 	int funcname;
 	char color_match[COLOR_MAXLEN];
-	const char *color_external;
 	int regflags;
 	unsigned pre_context;
 	unsigned post_context;
diff --git a/t/t7002-grep.sh b/t/t7002-grep.sh
index 76c5e091b..7eceb086b 100755
--- a/t/t7002-grep.sh
+++ b/t/t7002-grep.sh
@@ -8,18 +8,6 @@ test_description='git grep various.
 
 . ./test-lib.sh
 
-test_expect_success 'Check for external grep support' '
-	case "$(git grep -h 2>&1|grep ext-grep)" in
-	*"(default)"*)
-		test_set_prereq EXTGREP
-		true;;
-	*"(ignored by this build)"*)
-		true;;
-	*)
-		false;;
-	esac
-'
-
 cat >hello.c <<EOF
 #include <stdio.h>
 int main(int argc, const char **argv)
@@ -314,8 +302,8 @@ test_expect_success 'grep -C1, hunk mark between files' '
 	test_cmp expected actual
 '
 
-test_expect_success 'grep -C1 --no-ext-grep, hunk mark between files' '
-	git grep -C1 --no-ext-grep "^[yz]" >actual &&
+test_expect_success 'grep -C1 hunk mark between files' '
+	git grep -C1 "^[yz]" >actual &&
 	test_cmp expected actual
 '
 
@@ -371,7 +359,7 @@ test_expect_success 'log grep (6)' '
 test_expect_success 'grep with CE_VALID file' '
 	git update-index --assume-unchanged t/t &&
 	rm t/t &&
-	test "$(git grep --no-ext-grep test)" = "t/t:test" &&
+	test "$(git grep test)" = "t/t:test" &&
 	git update-index --no-assume-unchanged t/t &&
 	git checkout t/t
 '
@@ -438,16 +426,56 @@ test_expect_success 'grep -Fi' '
 	test_cmp expected actual
 '
 
-test_expect_success EXTGREP 'external grep is called' '
-	GIT_TRACE=2 git grep foo >/dev/null 2>actual &&
-	grep "trace: grep:.*foo" actual >/dev/null
+test_expect_success 'outside of git repository' '
+	rm -fr non &&
+	mkdir -p non/git/sub &&
+	echo hello >non/git/file1 &&
+	echo world >non/git/sub/file2 &&
+	echo ".*o*" >non/git/.gitignore &&
+	{
+		echo file1:hello &&
+		echo sub/file2:world
+	} >non/expect.full &&
+	echo file2:world >non/expect.sub
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non/git" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_must_fail git grep o &&
+		git grep --no-index o >../actual.full &&
+		test_cmp ../expect.full ../actual.full
+		cd sub &&
+		test_must_fail git grep o &&
+		git grep --no-index o >../../actual.sub &&
+		test_cmp ../../expect.sub ../../actual.sub
+	)
 '
 
-test_expect_success EXTGREP 'no external grep when skip-worktree entries exist' '
-	git update-index --skip-worktree file &&
-	GIT_TRACE=2 git grep foo >/dev/null 2>actual &&
-	! grep "trace: grep:" actual >/dev/null &&
-	git update-index --no-skip-worktree file
+test_expect_success 'inside git repository but with --no-index' '
+	rm -fr is &&
+	mkdir -p is/git/sub &&
+	echo hello >is/git/file1 &&
+	echo world >is/git/sub/file2 &&
+	echo ".*o*" >is/git/.gitignore &&
+	{
+		echo file1:hello &&
+		echo sub/file2:world
+	} >is/expect.full &&
+	: >is/expect.empty &&
+	echo file2:world >is/expect.sub
+	(
+		cd is/git &&
+		git init &&
+		test_must_fail git grep o >../actual.full &&
+		test_cmp ../expect.empty ../actual.full &&
+		git grep --no-index o >../actual.full &&
+		test_cmp ../expect.full ../actual.full &&
+		cd sub &&
+		test_must_fail git grep o >../../actual.sub &&
+		test_cmp ../../expect.empty ../../actual.sub &&
+		git grep --no-index o >../../actual.sub &&
+		test_cmp ../../expect.sub ../../actual.sub
+	)
 '
 
 test_done