Get worker VFS example to work

Author: simolus3

sqlite3/assets/wasm/bridge.h

@@ -27,6 +27,7 @@ import_dart("xFileSize") extern int xFileSize(int, int *pSize);
 import_dart("xLock") extern int xLock(int, int);
 import_dart("xUnlock") extern int xUnlock(int, int);
 import_dart("xCheckReservedLock") extern int xCheckReservedLock(int, int *pResOut);
+import_dart("xDeviceCharacteristics") extern int xDeviceCharacteristics(int);
 
 import_dart("function_xFunc") extern void dartXFunc(sqlite3_context *ctx,
                                                     int nArgs,

sqlite3/assets/wasm/helpers.c

@@ -79,10 +79,21 @@ int dartvfs_fileControl(sqlite3_file *file, int op, void *pArg) {
   return SQLITE_NOTFOUND;
 }
 
+int dartvfs_deviceCharacteristics(sqlite3_file *file) {
+  return xDeviceCharacteristics(DART_FD(file));
+}
+
+int dartvfs_sectorSize(sqlite3_file *file) {
+  // This is also the value of SQLITE_DEFAULT_SECTOR_SIZE, which would be picked if this function didn't exist.
+  // We need this method because vfstrace does not support null callbacks.
+  return 4096;
+}
+
 static int dartvfs_open(sqlite3_vfs* vfs, sqlite3_filename zName, sqlite3_file* file,
                int flags, int *pOutFlags) {
   dart_vfs_file* dartFile = (dart_vfs_file*) file;
-  memset(dartFile, sizeof(dart_vfs_file), 0);
+  memset(dartFile, 0, sizeof(dart_vfs_file));
+  dartFile->dart_fd = -1;
 
   static sqlite3_io_methods methods = {
       .iVersion = 1,
@@ -95,15 +106,21 @@ static int dartvfs_open(sqlite3_vfs* vfs, sqlite3_filename zName, sqlite3_file*
       .xLock = &dartvfs_lock,
       .xUnlock = &dartvfs_unlock,
       .xCheckReservedLock = &dartvfs_checkReservedLock,
-      .xFileControl = &dartvfs_fileControl
+      .xFileControl = &dartvfs_fileControl,
+      .xDeviceCharacteristics = &dartvfs_deviceCharacteristics,
+#ifdef SQLITE_ENABLE_VFSTRACE
+      .xSectorSize = &dartvfs_sectorSize
+#else
+      .xSectorSize = NULL
+#endif
   };
 
   int *dartFileId = &dartFile->dart_fd;
 
   // The xOpen call will also set the dart_fd field.
   int rc = xOpen((int) vfs->pAppData, zName, dartFileId, flags, pOutFlags);
 
-  if (*dartFileId != 0) {
+  if (*dartFileId != -1) {
     // sqlite3 will call xClose() even if this open call returns an error if methods
     // are set. So, we only provide the methods if a file has actually been opened.
     dartFile->pMethods = &methods;
@@ -144,7 +161,7 @@ static int dartvfs_currentTimeInt64(sqlite3_vfs* vfs, sqlite3_int64* timeOut) {
 
 SQLITE_API sqlite3_vfs* dart_sqlite3_register_vfs(const char* name, int dartId, int makeDefault) {
   sqlite3_vfs *vfs = calloc(1, sizeof(sqlite3_vfs));
-  vfs->iVersion = 3;
+  vfs->iVersion = 2;
   vfs->szOsFile = sizeof(dart_vfs_file);
   vfs->mxPathname = 1024;
   vfs->zName = name;
@@ -157,7 +174,20 @@ SQLITE_API sqlite3_vfs* dart_sqlite3_register_vfs(const char* name, int dartId,
   vfs->xSleep = &dartvfs_sleep;
   vfs->xCurrentTimeInt64 = &dartvfs_currentTimeInt64;
 
+#ifdef SQLITE_ENABLE_VFSTRACE
+  sqlite3_vfs_register(vfs, 0);
+
+  static const char* prefix = "trace_";
+  static const int prefixLength = 6;
+  char *traceName = malloc(strlen(name) + prefixLength);
+  strcpy(traceName, prefix);
+  strcpy(&traceName[prefixLength], name);
+
+  vfstrace_register(traceName, name, &dartvfs_trace_log1, NULL, makeDefault);
+#else
+  // Just register the VFS as is.
   sqlite3_vfs_register(vfs, makeDefault);
+#endif
   return vfs;
 }
 

sqlite3/example/web/worker.dart

@@ -1,12 +1,10 @@
 import 'dart:html';
-import 'dart:typed_data';
 
 import 'package:js/js.dart';
 import 'package:js/js_util.dart';
-import 'package:sqlite3/src/constants.dart';
-import 'package:sqlite3/src/vfs.dart';
 import 'package:sqlite3/src/wasm/vfs/async_opfs/client.dart';
 import 'package:sqlite3/src/wasm/vfs/async_opfs/worker.dart';
+import 'package:sqlite3/wasm.dart';
 
 @JS()
 external bool get crossOriginIsolated;
@@ -33,28 +31,19 @@ void main() {
       // Now, wait for the worker to report that it has been initialized.
       await worker.onMessage.first;
 
-      final vfs = WasmVfs(workerOptions: options);
-      final opened =
-          vfs.xOpen(Sqlite3Filename('/test'), SqlFlag.SQLITE_OPEN_CREATE);
-      final file = opened.file;
-      print('opened file $file, outflags ${opened.outFlags}');
+      final sqlite3 =
+          await WasmSqlite3.loadFromUrl(Uri.parse('sqlite3.debug.wasm'));
+      sqlite3.registerVirtualFileSystem(WasmVfs(workerOptions: options),
+          makeDefault: true);
 
-      final buffer = Uint8List.fromList([1, 2, 3, 4, 5, 6]);
-      file.xWrite(buffer, 0);
+      sqlite3.open('/tmp/foo.db')
+        ..execute('pragma user_version = 1')
+        ..execute('CREATE TABLE foo (bar INTEGER NOT NULL);')
+        ..execute('INSERT INTO foo (bar) VALUES (?)', [3])
+        ..dispose();
 
-      buffer.fillRange(0, 6, 0);
-      file.xRead(buffer, 0);
-      print('Buffer after read = $buffer');
-
-      print('size = ${file.xFileSize()}');
-      file.xTruncate(1024);
-      print('file after truncate: ${file.xFileSize()}');
-
-      file.xClose();
-      print('closed file');
-
-      vfs.xDelete('/test', 0);
-      print('deleted file');
+      final db = sqlite3.open('/tmp/foo.db');
+      print(db.select('SELECT * FROM foo'));
     } else {
       final message = data as WorkerOptions;
 

sqlite3/lib/src/constants.dart

@@ -487,9 +487,9 @@ class SqlTextEncoding {
 class SqlFileLockingLevels {
   static const SQLITE_LOCK_NONE = 0;
   static const SQLITE_LOCK_SHARED = 1;
-  static const SQLITE_LOCK_RESERVED = 0;
-  static const SQLITE_LOCK_PENDING = 0;
-  static const SQLITE_LOCK_EXCLUSIVE = 0;
+  static const SQLITE_LOCK_RESERVED = 2;
+  static const SQLITE_LOCK_PENDING = 3;
+  static const SQLITE_LOCK_EXCLUSIVE = 4;
 }
 
 /// Special destructors, https://www.sqlite.org/c3ref/c_static.html
@@ -518,6 +518,10 @@ class SqlFunctionFlag {
   static const SQLITE_INNOCUOUS = 0x000200000;
 }
 
+class SqlDeviceCharacteristics {
+  static const SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN = 0x00000800;
+}
+
 const SQLITE_DELETE = 9;
 const SQLITE_INSERT = 18;
 const SQLITE_UPDATE = 23;

sqlite3/lib/src/vfs.dart

@@ -130,6 +130,9 @@ abstract class VirtualFileSystemFile {
 
   /// Returns the lock state held by any process on this file.
   int xCheckReservedLock();
+
+  ///
+  int get xDeviceCharacteristics;
 }
 
 /// A [VirtualFileSystem] implementation that uses a [Random] instance for
@@ -162,6 +165,9 @@ abstract class BaseVfsFile implements VirtualFileSystemFile {
   /// must not be used after this function returns.
   int readInto(Uint8List buffer, int offset);
 
+  @override
+  int get xDeviceCharacteristics => 0;
+
   @override
   void xRead(Uint8List target, int fileOffset) {
     final bytesRead = readInto(target, fileOffset);