config: copy the return value of prefix_filename

The prefix_filename function returns a pointer to a static
buffer which may be overwritten by subsequent calls. Since
we are going to keep the result around for a while, let's be
sure to duplicate it for safety.

I don't think this can be triggered as a bug in the current
code, but it's a good idea to be defensive, as any resulting
bug would be quite subtle.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/config.c b/builtin/config.c
index d35c06ae51573eafbddd6309fda3f90ecef35d54..55854bef684752f1ca92d7081d536fbccaed6b1e 100644 (file)
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -377,9 +377,10 @@ int cmd_config(int argc, const char **argv, const char *prefix)
                config_exclusive_filename = git_pathdup("config");
        else if (given_config_file) {
                if (!is_absolute_path(given_config_file) && prefix)
-                       config_exclusive_filename = prefix_filename(prefix,
-                                                                   strlen(prefix),
-                                                                   given_config_file);
+                       config_exclusive_filename =
+                               xstrdup(prefix_filename(prefix,
+                                                       strlen(prefix),
+                                                       given_config_file));
                else
                        config_exclusive_filename = given_config_file;
        }