rename pathspec_prefix() to common_prefix() and move to dir.[ch]

Also make common_prefix_len() static as this refactoring makes dir.c
itself the only caller of this helper function.

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/dir.c b/dir.c
index 7bc75c944..6c0d78257 100644
--- a/dir.c
+++ b/dir.c
@@ -34,7 +34,7 @@ int fnmatch_icase(const char *pattern, const char *string, int flags)
 	return fnmatch(pattern, string, flags | (ignore_case ? FNM_CASEFOLD : 0));
 }
 
-size_t common_prefix_len(const char **pathspec)
+static size_t common_prefix_len(const char **pathspec)
 {
 	const char *n, *first;
 	size_t max = 0;
@@ -61,6 +61,17 @@ size_t common_prefix_len(const char **pathspec)
 	return max;
 }
 
+/*
+ * Returns a copy of the longest leading path common among all
+ * pathspecs.
+ */
+char *common_prefix(const char **pathspec)
+{
+	unsigned long len = common_prefix_len(pathspec);
+
+	return len ? xmemdupz(*pathspec, len) : NULL;
+}
+
 int fill_directory(struct dir_struct *dir, const char **pathspec)
 {
 	const char *path;