Allocate enough space for `cmd_results->error`

1 files changed, 10 insertions, 4 deletions

diff --git a/sway/commands.c b/sway/commands.c
index 0ced71ec..2160a970 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -485,13 +485,19 @@ struct cmd_results *cmd_results_new(enum cmd_status status,
         }
         results->status = status;
         if (format) {
-                char *error = malloc(256);
+                char *error = NULL;
                 va_list args;
                 va_start(args, format);
-                if (error) {
-                        vsnprintf(error, 256, format, args);
-                }
+                int slen = vsnprintf(NULL, 0, format, args);
                 va_end(args);
+                if (slen > 0) {
+                        error = malloc(slen + 1);
+                        if (error != NULL) {
+                                va_start(args, format);
+                                vsnprintf(error, slen + 1, format, args);
+                                va_end(args);
+                        }
+                }
                 results->error = error;
         } else {
                 results->error = NULL;