git_dir holds pointers to local strings, hence MUST be const.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

cache.h

@@ -123,7 +123,7 @@ extern int cache_errno;
 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
 #define GRAFT_ENVIRONMENT "GIT_GRAFT_FILE"
 
-extern char *get_git_dir(void);
+extern const char *get_git_dir(void);
 extern char *get_object_directory(void);
 extern char *get_refs_directory(void);
 extern char *get_index_file(void);

environment.c

@@ -25,8 +25,9 @@ int zlib_compression_level = Z_DEFAULT_COMPRESSION;
 int pager_in_use;
 int pager_use_color = 1;
 
-static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
-	*git_graft_file;
+static const char *git_dir;
+static char *git_object_dir, *git_index_file, *git_refs_dir, *git_graft_file;
+
 static void setup_git_env(void)
 {
 	git_dir = getenv(GIT_DIR_ENVIRONMENT);
@@ -49,7 +50,7 @@ static void setup_git_env(void)
 		git_graft_file = strdup(git_path("info/grafts"));
 }
 
-char *get_git_dir(void)
+const char *get_git_dir(void)
 {
 	if (!git_dir)
 		setup_git_env();