1 files changed, 49 insertions, 0 deletions
diff --git a/submodule.c b/submodule.c
index 3007f7d5a6..f657bee379 100644
--- a/submodule.c
+++ b/submodule.c
@@ -4,6 +4,7 @@
 #include "diff.h"
 #include "commit.h"
 #include "revision.h"
+#include "run-command.h"
 
 static int add_submodule_odb(const char *path)
 {
@@ -112,3 +113,51 @@ void show_submodule_summary(FILE *f, const char *path,
 	}
 	strbuf_release(&sb);
 }
+
+int is_submodule_modified(const char *path)
+{
+	int len;
+	struct child_process cp;
+	const char *argv[] = {
+		"status",
+		"--porcelain",
+		NULL,
+	};
+	char *env[3];
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_addf(&buf, "%s/.git/", path);
+	if (!is_directory(buf.buf)) {
+		strbuf_release(&buf);
+		/* The submodule is not checked out, so it is not modified */
+		return 0;
+
+	}
+	strbuf_reset(&buf);
+
+	strbuf_addf(&buf, "GIT_WORK_TREE=%s", path);
+	env[0] = strbuf_detach(&buf, NULL);
+	strbuf_addf(&buf, "GIT_DIR=%s/.git", path);
+	env[1] = strbuf_detach(&buf, NULL);
+	env[2] = NULL;
+
+	memset(&cp, 0, sizeof(cp));
+	cp.argv = argv;
+	cp.env = (const char *const *)env;
+	cp.git_cmd = 1;
+	cp.no_stdin = 1;
+	cp.out = -1;
+	if (start_command(&cp))
+		die("Could not run git status --porcelain");
+
+	len = strbuf_read(&buf, cp.out, 1024);
+	close(cp.out);
+
+	if (finish_command(&cp))
+		die("git status --porcelain failed");
+
+	free(env[0]);
+	free(env[1]);
+	strbuf_release(&buf);
+	return len != 0;
+}