rust: allow 65536,0 as a valid slice

wasmx · Feb 9, 2021 · c301265 · c301265
1 parent c985664
commit c301265
Showing 1 changed file with 7 additions and 5 deletions.
diff --git a/bindings/rust/src/lib.rs b/bindings/rust/src/lib.rs
@@ -299,7 +299,7 @@ impl Instance {
         let offset = offset as usize;
         let memory_size = self.memory_size();
         // Empty slices are allowed, but ensure both starting and ending offsets are valid.
-        if offset >= memory_size || (offset + size) > memory_size {
+        if memory_size == 0 || offset > memory_size || (offset + size) > memory_size {
             return Err(());
         }
         debug_assert!(memory_size != 0);
@@ -932,15 +932,17 @@ mod tests {
             // Allow empty slices.
             assert!(instance.checked_memory_slice(65535, 0).is_ok());
             assert!(instance.checked_memory_slice_mut(65535, 0).is_ok());
+            assert!(instance.checked_memory_slice(65536, 0).is_ok());
+            assert!(instance.checked_memory_slice_mut(65536, 0).is_ok());
             // Single byte.
             assert!(instance.checked_memory_slice(65535, 1).is_ok());
             assert!(instance.checked_memory_slice_mut(65535, 1).is_ok());
             // Reading over.
             assert!(instance.checked_memory_slice(65535, 2).is_err());
             assert!(instance.checked_memory_slice_mut(65535, 2).is_err());
             // Offset overflow.
-            assert!(instance.checked_memory_slice(65536, 0).is_err());
-            assert!(instance.checked_memory_slice_mut(65536, 0).is_err());
+            assert!(instance.checked_memory_slice(65537, 0).is_err());
+            assert!(instance.checked_memory_slice_mut(65537, 0).is_err());
         }
 
         // Grow with a single page.
@@ -996,7 +998,7 @@ mod tests {
         // Set memory via safe helper.
         assert!(instance.memory_set(0, &[]).is_ok());
         assert!(instance.memory_set(65536 + 65535, &[]).is_ok());
-        assert!(instance.memory_set(65536 + 65536, &[]).is_err());
+        assert!(instance.memory_set(65536 + 65536, &[]).is_ok());
         assert!(instance.memory_set(65536 + 65537, &[]).is_err());
         assert!(instance.memory_set(0, &[0x11, 0x22, 0x33, 0x44]).is_ok());
         assert!(instance
@@ -1052,7 +1054,7 @@ mod tests {
         // Read into empty slice.
         assert!(instance.memory_get(0, &mut dst[0..0]).is_ok());
         assert!(instance.memory_get(65536 + 65535, &mut dst[0..0]).is_ok());
-        assert!(instance.memory_get(65536 + 65536, &mut dst[0..0]).is_err());
+        assert!(instance.memory_get(65536 + 65536, &mut dst[0..0]).is_ok());
         assert!(instance.memory_get(65536 + 65537, &mut dst[0..0]).is_err());
 
         // Read into short slice.