swaygrab: Add some error handling.

- If IPC response contains `success: false`, abort and print error message.
- If tree has no nodes, abort with error msg instead of segfaulting.

1 files changed, 11 insertions, 1 deletions

diff --git a/swaygrab/json.c b/swaygrab/json.c
index 32b68612..286085c3 100644
--- a/swaygrab/json.c
+++ b/swaygrab/json.c
@@ -21,6 +21,14 @@ void init_json_tree(int socketfd) {
 	if (!tree || tok->err != json_tokener_success) {
 		sway_abort("Unable to parse IPC response as JSON: %s", json_tokener_error_desc(tok->err));
 	}
+	json_object *success;
+	json_object_object_get_ex(tree, "success", &success);
+	if (success && !json_object_get_boolean(success)) {
+		json_object *error;
+		json_object_object_get_ex(tree, "error", &error);
+		sway_abort("IPC request failed: %s", json_object_get_string(error));
+	}
+	json_object_put(success);
 	json_tokener_free(tok);
 }
 
@@ -72,7 +80,9 @@ json_object *get_focused_container() {
 char *get_focused_output() {
 	json_object *outputs, *output, *name;
 	json_object_object_get_ex(tree, "nodes", &outputs);
-
+	if (!outputs) {
+		sway_abort("Unabled to get focused output. No nodes in tree.");
+	}
 	for (int i = 0; i < json_object_array_length(outputs); i++) {
 		output = json_object_array_get_idx(outputs, i);