config: share the strmap on snapshot

Now that our strmap is no longer modified but replaced, we can use the
same strmap for the snapshot's values and it will be freed when we don't
need it anymore.

src/config_file.c

@@ -762,71 +762,19 @@ static void backend_readonly_free(git_config_backend *_backend)
 	git__free(backend);
 }
 
-static int config_entry_dup(git_config_entry **out, git_config_entry *src)
-{
-	git_config_entry *entry;
-
-	entry = git__calloc(1, sizeof(git_config_entry));
-	GITERR_CHECK_ALLOC(entry);
-
-	entry->level = src->level;
-	entry->name = git__strdup(src->name);
-	GITERR_CHECK_ALLOC(entry->name);
-	entry->value = git__strdup(src->value);
-	GITERR_CHECK_ALLOC(entry->value);
-
-	*out = entry;
-
-	return 0;
-}
-
 static int config_readonly_open(git_config_backend *cfg, git_config_level_t level)
 {
 	diskfile_readonly_backend *b = (diskfile_readonly_backend *) cfg;
 	diskfile_backend *src = b->snapshot_from;
 	refcounted_strmap *src_map;
-	git_strmap *src_values, *values;
-	git_strmap_iter i;
-	cvar_t *src_var;
-	int error;
 
 	/* We're just copying data, don't care about the level */
 	GIT_UNUSED(level);
 
-	if ((error = refcounted_strmap_alloc(&b->header.values)) < 0)
-		return error;
-
 	src_map = refcounted_strmap_take(&src->header);
-	src_values = src->header.values->values;
-	values = b->header.values->values;
-
-	i = git_strmap_begin(src_values);
-	while ((error = git_strmap_next((void **) &src_var, &i, src_values)) == 0) {
-		do {
-			git_config_entry *entry;
-			cvar_t *var;
-
-			var = git__calloc(1, sizeof(cvar_t));
-			GITERR_CHECK_ALLOC(var);
-
-			if (config_entry_dup(&entry, src_var->entry) < 0) {
-				refcounted_strmap_free(b->header.values);
-				refcounted_strmap_free(src_map);
-				return -1;
-			}
+	b->header.values = src_map;
 
-			var->entry = entry;
-
-			error = append_entry(values, var);
-			src_var = CVAR_LIST_NEXT(src_var);
-		} while (src_var != NULL && error == 0);
-	}
-
-	if (error == GIT_ITEROVER)
-		error = 0;
-
-	refcounted_strmap_free(src_map);
-	return error;
+	return 0;
 }
 
 int git_config_file__snapshot(git_config_backend **out, diskfile_backend *in)