Merge PR #885

crates/engine/src/cmd/query.rs

@@ -59,6 +59,12 @@ fn photo_arg(s: &Session, p: &Value, c: &str) -> crate::Result<PhotoId> {
     }
 }
 
+// Catalog queries also run in the 32-bit web build. A narrowing cast wraps
+// an out-of-range offset to zero, returning the first page instead of no photos.
+fn pagination_usize(value: u64) -> usize {
+    usize::try_from(value).unwrap_or(usize::MAX)
+}
+
 pub fn specs() -> Vec<CommandSpec> {
     vec![
         cmd!(query "catalog.query", "Query Photos", [], None, "{filter?: Filter, sort?: Sort, offset?, limit?} — omit filter to list the current view", always, |s, p| {
@@ -69,8 +75,8 @@ pub fn specs() -> Vec<CommandSpec> {
             } else {
                 s.visible_cloned()
             };
-            let off = p.get("offset").and_then(Value::as_u64).unwrap_or(0) as usize;
-            let lim = p.get("limit").and_then(Value::as_u64).unwrap_or(200) as usize;
+            let off = pagination_usize(p.get("offset").and_then(Value::as_u64).unwrap_or(0));
+            let lim = pagination_usize(p.get("limit").and_then(Value::as_u64).unwrap_or(200));
             let items: Vec<Value> = ids.iter().skip(off).take(lim).filter_map(|id| s.catalog.photo(*id)).map(|p| photo_summary(p)).collect();
             Ok(json!({"total": ids.len(), "photos": items}))
         }),
@@ -237,3 +243,17 @@ pub fn specs() -> Vec<CommandSpec> {
         }),
     ]
 }
+
+#[cfg(test)]
+mod pagination_tests {
+    use super::*;
+
+    #[test]
+    fn offsets_and_limits_saturate_instead_of_wrapping_on_wasm() {
+        assert_eq!(pagination_usize(0), 0);
+        assert_eq!(pagination_usize(200), 200);
+        assert_eq!(pagination_usize(u64::MAX), usize::MAX);
+        #[cfg(target_pointer_width = "32")]
+        assert_eq!(pagination_usize(u64::from(u32::MAX) + 1), usize::MAX);
+    }
+}