More VFS API.

sqlite3vfs/const.go

@@ -96,3 +96,26 @@ const (
 	// time that EXCLUSIVE locks are held.
 	LOCK_EXCLUSIVE LockLevel = 4 /* xLock() only */
 )
+
+// DeviceCharacteristic is a flag retuned by the [File.DeviceCharacteristic] method.
+//
+// https://www.sqlite.org/c3ref/c_iocap_atomic.html
+type DeviceCharacteristic uint32
+
+const (
+	IOCAP_ATOMIC                DeviceCharacteristic = 0x00000001
+	IOCAP_ATOMIC512             DeviceCharacteristic = 0x00000002
+	IOCAP_ATOMIC1K              DeviceCharacteristic = 0x00000004
+	IOCAP_ATOMIC2K              DeviceCharacteristic = 0x00000008
+	IOCAP_ATOMIC4K              DeviceCharacteristic = 0x00000010
+	IOCAP_ATOMIC8K              DeviceCharacteristic = 0x00000020
+	IOCAP_ATOMIC16K             DeviceCharacteristic = 0x00000040
+	IOCAP_ATOMIC32K             DeviceCharacteristic = 0x00000080
+	IOCAP_ATOMIC64K             DeviceCharacteristic = 0x00000100
+	IOCAP_SAFE_APPEND           DeviceCharacteristic = 0x00000200
+	IOCAP_SEQUENTIAL            DeviceCharacteristic = 0x00000400
+	IOCAP_UNDELETABLE_WHEN_OPEN DeviceCharacteristic = 0x00000800
+	IOCAP_POWERSAFE_OVERWRITE   DeviceCharacteristic = 0x00001000
+	IOCAP_IMMUTABLE             DeviceCharacteristic = 0x00002000
+	IOCAP_BATCH_ATOMIC          DeviceCharacteristic = 0x00004000
+)

sqlite3vfs/vfs.go

@@ -20,6 +20,28 @@ type File interface {
 	Unlock(lock LockLevel) error
 	CheckReservedLock() (bool, error)
 	SectorSize() int
+	DeviceCharacteristics() DeviceCharacteristic
+}
+
+type FileLockState interface {
+	File
+	LockState() LockLevel
+}
+
+type FileSizeHint interface {
+	File
+	SizeHint(size int64) error
+}
+
+type FileHasMoved interface {
+	File
+	HasMoved() (bool, error)
+}
+
+type FilePowersafeOverwrite interface {
+	File
+	PowersafeOverwrite() bool
+	SetPowersafeOverwrite(bool)
 }
 
 var (