Move offset_1st_component() to path.c

The implementation is also lightly modified to use is_dir_sep()
instead of hardcoding '/'.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

cache.h

@@ -664,6 +664,7 @@ int normalize_path_copy(char *dst, const char *src);
 int longest_ancestor_length(const char *path, const char *prefix_list);
 char *strip_path_suffix(const char *path, const char *suffix);
 int daemon_avoid_alias(const char *path);
+int offset_1st_component(const char *path);
 
 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 extern int sha1_object_info(const unsigned char *, unsigned long *);

path.c

@@ -649,3 +649,10 @@ int daemon_avoid_alias(const char *p)
 		}
 	}
 }
+
+int offset_1st_component(const char *path)
+{
+	if (has_dos_drive_prefix(path))
+		return 2 + is_dir_sep(path[2]);
+	return is_dir_sep(path[0]);
+}

sha1_file.c

@@ -83,13 +83,6 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)
 	return 0;
 }
 
-static inline int offset_1st_component(const char *path)
-{
-	if (has_dos_drive_prefix(path))
-		return 2 + (path[2] == '/');
-	return *path == '/';
-}
-
 int safe_create_leading_directories(char *path)
 {
 	char *pos = path + offset_1st_component(path);