fix: restore WASM stack in Database.exec to prevent stack leak (#630)

src/api.js

@@ -946,6 +946,7 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
         if (!this.db) {
             throw "Database closed";
         }
+        var stack = stackSave();
         var stmt = null;
         var originalSqlPtr = null;
         var currentSqlPtr = null;
@@ -993,6 +994,7 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
             throw errCaught;
         } finally {
             if (originalSqlPtr) _free(originalSqlPtr);
+            stackRestore(stack);
         }
     };
 

test/test_issue630.js

@@ -0,0 +1,48 @@
+
+exports.test = function(sql, assert) {
+    "use strict";
+    var db = new sql.Database();
+    db.run("CREATE TABLE t (x); INSERT INTO t VALUES (1);");
+
+    var before = sql.stackSave();
+    for (var i = 0; i < 1000; i++) {
+        db.exec("SELECT x FROM t");
+    }
+    assert.strictEqual(
+        before - sql.stackSave(),
+        0,
+        "exec() should not leak stack memory after repeated successful calls"
+    );
+
+    for (var j = 0; j < 100; j++) {
+        assert.throws(
+            function () { db.exec("SELECT * FROM does_not_exist"); },
+            "no such table: does_not_exist",
+            "exec() should throw for a failing query"
+        );
+    }
+    assert.strictEqual(
+        before - sql.stackSave(),
+        0,
+        "exec() should not leak stack memory after repeated failing calls"
+    );
+
+    // Close the database and all associated statements
+    db.close();
+};
+
+if (module == require.main) {
+  const target_file = process.argv[2];
+  const sql_loader = require('./load_sql_lib');
+  sql_loader(target_file).then((sql)=>{
+    require('test').run({
+      'test issue630': function(assert){
+        exports.test(sql, assert);
+      }
+    });
+  })
+  .catch((e)=>{
+    console.error(e);
+    assert.fail(e);
+  });
+}