config: don't allow passing NULL as a value to set

Passing NULL is non-sensical. The error message leaves to be desired,
though, as it leaks internal implementation details. Catch it at the
`git_config_set_string` level and set an appropriate error message.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/config.c b/src/config.c
index d6aa3078c..c7022891d 100644
--- a/src/config.c
+++ b/src/config.c
@@ -362,6 +362,11 @@ int git_config_set_string(git_config *cfg, const char *name, const char *value)
 	git_config_backend *file;
 	file_internal *internal;
 
+	if (!value) {
+		giterr_set(GITERR_CONFIG, "The value to set cannot be NULL");
+		return -1;
+	}
+
 	internal = git_vector_get(&cfg->files, 0);
 	file = internal->file;