Fix writing large blobs through opfs-locks

Author: simolus3

sqlite3/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.6.1
+
+- Fix out-of-bound reads in the `xWrite` implementation of the OPFS-locks based
+  file-system implementation when writing more than 64 KiB in one operation.
+
 ## 2.6.0
 
 - Add `SimpleOpfsFileSystem.deleteFromStorage` to delete OPFS-based file

sqlite3/lib/src/wasm/vfs/async_opfs/client.dart

@@ -202,9 +202,11 @@ class WasmFile extends BaseVfsFile {
       // buffer would otherwise overflow.
       final bytesToWrite = min(MessageSerializer.dataSize, remainingBytes);
 
-      final subBuffer = bytesToWrite == remainingBytes
-          ? buffer
-          : buffer.buffer.asUint8List(buffer.offsetInBytes, bytesToWrite);
+      final subBuffer =
+          (bytesToWrite == remainingBytes && totalBytesWritten == 0)
+              ? buffer
+              : buffer.buffer.asUint8List(
+                  buffer.offsetInBytes + totalBytesWritten, bytesToWrite);
       vfs.serializer.byteView.set(subBuffer, 0);
 
       vfs._runInWorker(WorkerOperation.xWrite,

sqlite3/pubspec.yaml

@@ -1,6 +1,6 @@
 name: sqlite3
 description: Provides lightweight yet convenient bindings to SQLite by using dart:ffi
-version: 2.6.0
+version: 2.6.1
 homepage: https://github.com/simolus3/sqlite3.dart/tree/main/sqlite3
 issue_tracker: https://github.com/simolus3/sqlite3.dart/issues
 

sqlite3_web/test/integration_test.dart

@@ -181,6 +181,16 @@ void main() {
             await driver.assertFile(false);
           }
         });
+
+        test('check large write and read', () async {
+          await driver.openDatabase(
+            implementation: (storage, access),
+            onlyOpenVfs: true,
+          );
+          await driver.assertFile(false);
+
+          await driver.checkReadWrite();
+        });
       }
     });
   }

sqlite3_web/tool/server.dart

@@ -209,6 +209,14 @@ class TestWebDriver {
     }
   }
 
+  Future<void> checkReadWrite() async {
+    final result =
+        await driver.executeAsync('check_read_write("", arguments[0])', []);
+    if (result != null) {
+      throw 'check_read_write() failed: $result';
+    }
+  }
+
   Future<void> delete(StorageMode mode) async {
     await driver
         .executeAsync('delete_db(arguments[0], arguments[1])', [mode.name]);

sqlite3_web/web/main.dart

@@ -2,6 +2,7 @@ import 'dart:convert';
 import 'dart:html';
 import 'dart:js_interop';
 import 'dart:js_interop_unsafe';
+import 'dart:typed_data';
 
 import 'package:sqlite3_web/sqlite3_web.dart';
 
@@ -64,6 +65,29 @@ void main() {
         .deleteDatabase(name: databaseName, storage: storage);
     return true.toJS;
   });
+  _addCallbackForWebDriver('check_read_write', (arg) async {
+    final vfs = database!.fileSystem;
+
+    final bytes = Uint8List(1024 * 128);
+    for (var i = 0; i < 128; i++) {
+      bytes[i * 1024] = i;
+    }
+
+    await vfs.writeFile(FileType.database, bytes);
+    await vfs.flush();
+    final result = await vfs.readFile(FileType.database);
+    if (result.length != bytes.length) {
+      return 'length mismatch'.toJS;
+    }
+
+    for (var i = 0; i < 128; i++) {
+      if (result[i * 1024] != i) {
+        return 'mismatch, i=$i, byte ${result[i * 1024]}'.toJS;
+      }
+    }
+
+    return null;
+  });
 
   document.getElementById('selfcheck')?.onClick.listen((event) async {
     print('starting');