Batch atomic writes API.

vfs/api.go

@@ -80,3 +80,15 @@ type FilePowersafeOverwrite interface {
 	PowersafeOverwrite() bool
 	SetPowersafeOverwrite(bool)
 }
+
+// FileBatchAtomicWrite extends File to implement the
+// SQLITE_FCNTL_BEGIN_ATOMIC_WRITE, SQLITE_FCNTL_COMMIT_ATOMIC_WRITE
+// and SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE file control opcodes.
+//
+// https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
+type FileBatchAtomicWrite interface {
+	File
+	BeginAtomicWrite() error
+	CommitAtomicWrite() error
+	RollbackAtomicWrite() error
+}

vfs/const.go

@@ -39,6 +39,9 @@ const (
 	_IOERR_CLOSE             _ErrorCode = util.IOERR_CLOSE
 	_IOERR_SEEK              _ErrorCode = util.IOERR_SEEK
 	_IOERR_DELETE_NOENT      _ErrorCode = util.IOERR_DELETE_NOENT
+	_IOERR_BEGIN_ATOMIC      _ErrorCode = util.IOERR_BEGIN_ATOMIC
+	_IOERR_COMMIT_ATOMIC     _ErrorCode = util.IOERR_COMMIT_ATOMIC
+	_IOERR_ROLLBACK_ATOMIC   _ErrorCode = util.IOERR_ROLLBACK_ATOMIC
 	_CANTOPEN_FULLPATH       _ErrorCode = util.CANTOPEN_FULLPATH
 	_CANTOPEN_ISDIR          _ErrorCode = util.CANTOPEN_ISDIR
 	_OK_SYMLINK              _ErrorCode = util.OK_SYMLINK

vfs/vfs.go

@@ -335,12 +335,30 @@ func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _Fcntl
 			util.WriteUint32(mod, pArg, res)
 			return vfsErrorCode(err, _IOERR_FSTAT)
 		}
+
+	case _FCNTL_BEGIN_ATOMIC_WRITE:
+		if file, ok := file.(FileBatchAtomicWrite); ok {
+			err := file.BeginAtomicWrite()
+			return vfsErrorCode(err, _IOERR_BEGIN_ATOMIC)
+		}
+	case _FCNTL_COMMIT_ATOMIC_WRITE:
+		if file, ok := file.(FileBatchAtomicWrite); ok {
+			err := file.CommitAtomicWrite()
+			return vfsErrorCode(err, _IOERR_COMMIT_ATOMIC)
+		}
+	case _FCNTL_ROLLBACK_ATOMIC_WRITE:
+		if file, ok := file.(FileBatchAtomicWrite); ok {
+			err := file.RollbackAtomicWrite()
+			return vfsErrorCode(err, _IOERR_ROLLBACK_ATOMIC)
+		}
 	}
 
 	// Consider also implementing these opcodes (in use by SQLite):
 	//  _FCNTL_PDB
 	//  _FCNTL_BUSYHANDLER
+	//	_FCNTL_CHUNK_SIZE
 	//  _FCNTL_COMMIT_PHASETWO
+	//	_FCNTL_OVERWRITE
 	//  _FCNTL_PRAGMA
 	//  _FCNTL_SYNC
 	return _NOTFOUND