From 7719755a52a56126a88c3d6898d27779865e8f09 Mon Sep 17 00:00:00 2001
From: Ry <ryanst755@gmail.com>
Date: Mon, 30 Jan 2023 14:07:43 -0800
Subject: [PATCH] Cleanly exit if attempting to open non-existent disk

Fixes issue #7.
---
 src/disk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/disk.c b/src/disk.c
index bac0503..27ea0f7 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -19,6 +19,10 @@ void new_disk(const char *filename, size_t id) {
     if (id > 3) { puts("attempting to access disk with ID > 3\n"); return; }
     printf("mounting %s as disk ID %d\n", filename, (int) id);
     disk_controller.disks[id].file = fopen(filename, "r+b");
+    if (!disk_controller.disks[id].file) {
+        fprintf(stderr, "couldn't open disk file\n");
+        exit(1);
+    }
     fseek(disk_controller.disks[id].file, 0, SEEK_END);
     disk_controller.disks[id].size = ftell(disk_controller.disks[id].file);
     rewind(disk_controller.disks[id].file);