From c9fe2c22fa76942d1f18ccff6b1c378f95e102c3 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Fri, 4 Sep 2020 21:53:48 +0100
Subject: [PATCH] defend against PosOffTable in spec

---
 src/cmdlistener.rs | 3 +++
 src/spec.rs        | 1 +
 src/updates.rs     | 2 --
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/cmdlistener.rs b/src/cmdlistener.rs
index 1e762809..226598c2 100644
--- a/src/cmdlistener.rs
+++ b/src/cmdlistener.rs
@@ -250,6 +250,9 @@ fn execute_game_insn(cs: &CommandStream,
           gen: gs.gen,
           pos, p, face,
         };
+        if let (_, true) = pc.pos.clamped(gs.table_size) {
+          throw!(SpecError::PosOffTable);
+        }
         let piece = gs.pieces.insert(pc);
         updates.push((piece, PieceUpdateOp::Insert(())));
         pos[0] += posd[0];
diff --git a/src/spec.rs b/src/spec.rs
index a2e5e349..f13d6bcb 100644
--- a/src/spec.rs
+++ b/src/spec.rs
@@ -35,6 +35,7 @@ pub enum SpecError {
   UnsupportedColourSpec,
   FaceNotFound,
   InternalError(String),
+  PosOffTable,
 }
 display_as_debug!{SpecError}
 
diff --git a/src/updates.rs b/src/updates.rs
index 47de5eb7..559bf702 100644
--- a/src/updates.rs
+++ b/src/updates.rs
@@ -256,8 +256,6 @@ impl<'r> PrepareUpdatesBuffer<'r> {
                            lens: &dyn Lens) -> PreparedUpdateEntry {
     let gs = &mut self.g.gs;
 
-    // xxx enforce pos is within range,  everywhere
-
     let (update, piece) = match gs.pieces.byid_mut(piece) {
       Ok(pc) => {
         gs.max_z.update_max(pc.zlevel.z);
-- 
2.30.2