From cfd5be1bc59fd5fe1b30f29efb442ca1c0c26e57 Mon Sep 17 00:00:00 2001
From: Misa <infoteddy@infoteddy.info>
Date: Wed, 24 Mar 2021 11:51:39 -0700
Subject: [PATCH] Add bounds checks to tile setter and getters

This removes all traces of Undefined Behavior from getting and placing
tiles.

This mimics the previous behavior (2.2 and below) as reasonably as
possible. `vmult` was previously a vector, there was a bunch of unused
space directly after the end of the usable space of the vector, which
was all filled with zeroes. The same goes for `contents`, having
previously been a vector, and so having a bunch of zeroes immediately
following the end of the in-bounds space. That's why both are 0 if you
index them out of bounds.
---
 desktop_version/src/editor.cpp | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/desktop_version/src/editor.cpp b/desktop_version/src/editor.cpp
index 1ca46303..1536be52 100644
--- a/desktop_version/src/editor.cpp
+++ b/desktop_version/src/editor.cpp
@@ -951,7 +951,14 @@ int editorclass::gettileidx(
     int mult;
     int idx;
 
-    mult = vmult[yoff];
+    if (INBOUNDS_ARR(yoff, vmult))
+    {
+        mult = vmult[yoff];
+    }
+    else
+    {
+        mult = 0;
+    }
 
     idx = x + rx*40 + mult;
 
@@ -967,6 +974,11 @@ void editorclass::settile(
 ) {
     const int idx = gettileidx(rx, ry, x, y);
 
+    if (!INBOUNDS_ARR(idx, contents))
+    {
+        return;
+    }
+
     contents[idx] = t;
 }
 
@@ -978,6 +990,11 @@ int editorclass::gettile(
 ) {
     const int idx = gettileidx(rx, ry, x, y);
 
+    if (!INBOUNDS_ARR(idx, contents))
+    {
+        return 0;
+    }
+
     return contents[idx];
 }
 
@@ -986,10 +1003,22 @@ int editorclass::getabstile(const int x, const int y)
     int idx;
     int yoff;
 
-    yoff = vmult[y];
+    if (INBOUNDS_ARR(y, vmult))
+    {
+        yoff = vmult[y];
+    }
+    else
+    {
+        yoff = 0;
+    }
 
     idx = x + yoff;
 
+    if (!INBOUNDS_ARR(idx, contents))
+    {
+        return 0;
+    }
+
     return contents[idx];
 }