git_config_set_multivar_in_file: handle "unset" errors

We pass off to the "_gently" form to do the real work, and
just die() if it returned an error. However, our die message
de-references "value", which may be NULL if the request was
to unset a variable. Nobody using glibc noticed, because it
simply prints "(null)", which is good enough for the test
suite (and presumably very few people run across this in
practice). But other libc implementations (like Solaris) may
segfault.

Let's not only fix that, but let's make the message more
clear about what is going on in the "unset" case.

Reported-by: "Tom G. Christensen" <tgc@jupiterrise.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.c b/config.c
index d349d52f26365b489d7d997d5f281f0f4abe7193..68a2f939efc8f312bf089485d0443fafe1af937c 100644 (file)
--- a/config.c
+++ b/config.c
@@ -2221,9 +2221,13 @@ void git_config_set_multivar_in_file(const char *config_filename,
                                     const char *key, const char *value,
                                     const char *value_regex, int multi_replace)
 {
-       if (git_config_set_multivar_in_file_gently(config_filename, key, value,
-                                                  value_regex, multi_replace))
+       if (!git_config_set_multivar_in_file_gently(config_filename, key, value,
+                                                   value_regex, multi_replace))
+               return;
+       if (value)
                die(_("could not set '%s' to '%s'"), key, value);
+       else
+               die(_("could not unset '%s'"), key);
 }
 
 int git_config_set_multivar_gently(const char *key, const char *value,