From 5782e29db43034574763b1d10c48486c3e95f0d2 Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Mon, 9 Jan 2023 20:24:15 +0000
Subject: [PATCH] Tracks: make sure moves are valid in execute_move()

Tracks allowed moves in execute_move() that shouldn't have been allowed,
like changing the state of the edges of the board.  This moves couldn't
be generated by interpret_move(), but could be loaded from a save file.
Now execute_move() uses the same ui_can_flip_*() functions as
interpret_move() to decide whether a particular move is allowed.  This
should prevent some assertion failures when loading corrupted save
files.
---
 tracks.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tracks.c b/tracks.c
index 674be4a..443a62a 100644
--- a/tracks.c
+++ b/tracks.c
@@ -2429,6 +2429,8 @@ static game_state *execute_move(const game_state *state, const char *move)
             f = (c == 'T' || c == 't') ? S_TRACK : S_NOTRACK;
 
             if (d == 'S') {
+                if (!ui_can_flip_square(ret, x, y, f == S_NOTRACK))
+                    goto badmove;
                 if (c == 'T' || c == 'N')
                     ret->sflags[y*w+x] |= f;
                 else
@@ -2438,6 +2440,8 @@ static game_state *execute_move(const game_state *state, const char *move)
                     unsigned df = 1<<i;
 
                     if (MOVECHAR(df) == d) {
+                        if (!ui_can_flip_edge(ret, x, y, df, f == S_NOTRACK))
+                            goto badmove;
                         if (c == 'T' || c == 'N')
                             S_E_SET(ret, x, y, df, f);
                         else