[RFC PATCH 3/3] grep: add support for grepping in submodules

[Chris Packham <judge.packham@gmail.com>]

When the --recurse-submodules option is given git grep will search in
submodules as they are encountered.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
---
 builtin/grep.c |   72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 grep.h         |    1 +
 2 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/builtin/grep.c b/builtin/grep.c
index 8315ff0..c9befdc 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -30,6 +30,9 @@ static char const * const grep_usage[] = {
 
 static int use_threads = 1;
 
+static int saved_argc;
+static const char **saved_argv;
+
 #ifndef NO_PTHREADS
 #define THREADS 8
 static pthread_t threads[THREADS];
@@ -585,6 +588,67 @@ static void run_pager(struct grep_opt *opt, const char *prefix)
 	free(argv);
 }
 
+static const char **create_sub_grep_argv(struct grep_opt *opt, const char *path)
+{
+	#define NUM_ARGS 10
+	struct strbuf buf = STRBUF_INIT;
+	const char **argv;
+	int i = 0;
+
+	argv = xcalloc(NUM_ARGS, sizeof(const char *));
+	argv[i++] = "grep";
+	strbuf_addf(&buf, "--submodule-prefix=\\\"%s\\\"", path);
+	//argv[i++] = buf.buf;
+
+	if (opt->linenum)
+		argv[i++] = "-n";
+	if (opt->invert)
+		argv[i++] = "-v";
+	if (opt->ignore_case)
+		argv[i++] = "-i";
+	if (opt->count)
+		argv[i++] = "-c";
+	if (opt->name_only)
+		argv[i++] = "-l";
+
+	argv[i++] = saved_argv[0];
+	argv[i++] = NULL;
+
+	strbuf_release(&buf);
+	return argv;
+}
+
+static int grep_submodule(struct grep_opt *opt, const char *path)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct child_process cp;	
+	const char **argv = create_sub_grep_argv(opt, path);
+	const char *git_dir;
+	int hit = 0;
+
+	strbuf_addf(&buf, "%s/.git", path);
+	git_dir = read_gitfile_gently(buf.buf);
+	if (!git_dir)
+		git_dir = buf.buf;
+	if (!is_directory(git_dir)) {
+		warning("submodule %s has not been initialized\n", path);
+		goto out_free;
+	}
+
+	memset(&cp, 0, sizeof(cp));
+	cp.argv = argv;
+	cp.env = local_repo_env;
+	cp.git_cmd = 1;
+	cp.no_stdin = 1;
+	cp.dir = path;
+	if (run_command(&cp) == 0)
+		hit = 1;
+out_free:
+	free(argv);
+	strbuf_release(&buf);
+	return hit;
+}
+
 static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 {
 	int hit = 0;
@@ -593,6 +657,10 @@ static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 
 	for (nr = 0; nr < active_nr; nr++) {
 		struct cache_entry *ce = active_cache[nr];
+		if (S_ISGITLINK(ce->ce_mode) && opt->recurse_submodules) {
+			hit |= grep_submodule(opt, ce->name);
+			continue;
+		}
 		if (!S_ISREG(ce->ce_mode))
 			continue;
 		if (!pathspec_matches(paths, ce->name, opt->max_depth))
@@ -929,9 +997,13 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		  PARSE_OPT_HIDDEN | PARSE_OPT_NOARG, help_callback },
 		OPT_STRING(0, "submodule-prefix", &opt.submodule_prefix, "DIR",
 			"prepend this to submodule path output"),
+		OPT_BOOLEAN(0, "recurse-submodules", &opt.recurse_submodules,
+			"recurse into submodules"),
 		OPT_END()
 	};
 
+	saved_argc = argc;
+	saved_argv = argv;
 	/*
 	 * 'git grep -h', unlike 'git grep -h <pattern>', is a request
 	 * to show usage information and exit.
diff --git a/grep.h b/grep.h
index d918da4..e3199c9 100644
--- a/grep.h
+++ b/grep.h
@@ -102,6 +102,7 @@ struct grep_opt {
 	unsigned post_context;
 	unsigned last_shown;
 	int show_hunk_mark;
+	int recurse_submodules;
 	void *priv;
 
 	void (*output)(struct grep_opt *opt, const void *data, size_t size);
-- 
1.7.3.dirty