blob: b220713f2d40b7b765fafbb30a8f8b2925c783fe [file] [log] [blame]
package driver
import (
// Version is a string representing the storage driver version, of the form
// Major.Minor.
// The registry must accept storage drivers with equal major version and greater
// minor version, but may not be compatible with older storage driver versions.
type Version string
// Major returns the major (primary) component of a version.
func (version Version) Major() uint {
majorPart := strings.Split(string(version), ".")[0]
major, _ := strconv.ParseUint(majorPart, 10, 0)
return uint(major)
// Minor returns the minor (secondary) component of a version.
func (version Version) Minor() uint {
minorPart := strings.Split(string(version), ".")[1]
minor, _ := strconv.ParseUint(minorPart, 10, 0)
return uint(minor)
// CurrentVersion is the current storage driver Version.
const CurrentVersion Version = "0.1"
// StorageDriver defines methods that a Storage Driver must implement for a
// filesystem-like key/value object storage. Storage Drivers are automatically
// registered via an internal registration mechanism, and generally created
// via the StorageDriverFactory interface (
// Please see the aforementioned factory package for example code showing how to get an instance
// of a StorageDriver
type StorageDriver interface {
// Name returns the human-readable "name" of the driver, useful in error
// messages and logging. By convention, this will just be the registration
// name, but drivers may provide other information here.
Name() string
// GetContent retrieves the content stored at "path" as a []byte.
// This should primarily be used for small objects.
GetContent(ctx context.Context, path string) ([]byte, error)
// PutContent stores the []byte content at a location designated by "path".
// This should primarily be used for small objects.
PutContent(ctx context.Context, path string, content []byte) error
// Reader retrieves an io.ReadCloser for the content stored at "path"
// with a given byte offset.
// May be used to resume reading a stream by providing a nonzero offset.
Reader(ctx context.Context, path string, offset int64) (io.ReadCloser, error)
// Writer returns a FileWriter which will store the content written to it
// at the location designated by "path" after the call to Commit.
Writer(ctx context.Context, path string, append bool) (FileWriter, error)
// Stat retrieves the FileInfo for the given path, including the current
// size in bytes and the creation time.
Stat(ctx context.Context, path string) (FileInfo, error)
// List returns a list of the objects that are direct descendants of the
//given path.
List(ctx context.Context, path string) ([]string, error)
// Move moves an object stored at sourcePath to destPath, removing the
// original object.
// Note: This may be no more efficient than a copy followed by a delete for
// many implementations.
Move(ctx context.Context, sourcePath string, destPath string) error
// Delete recursively deletes all objects stored at "path" and its subpaths.
Delete(ctx context.Context, path string) error
// URLFor returns a URL which may be used to retrieve the content stored at
// the given path, possibly using the given options.
// May return an ErrUnsupportedMethod in certain StorageDriver
// implementations.
URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error)
// Walk traverses a filesystem defined within driver, starting
// from the given path, calling f on each file.
// If the returned error from the WalkFn is ErrSkipDir and fileInfo refers
// to a directory, the directory will not be entered and Walk
// will continue the traversal. If fileInfo refers to a normal file, processing stops
Walk(ctx context.Context, path string, f WalkFn) error
// FileWriter provides an abstraction for an opened writable file-like object in
// the storage backend. The FileWriter must flush all content written to it on
// the call to Close, but is only required to make its content readable on a
// call to Commit.
type FileWriter interface {
// Size returns the number of bytes written to this FileWriter.
Size() int64
// Cancel removes any written content from this FileWriter.
Cancel() error
// Commit flushes all content written to this FileWriter and makes it
// available for future calls to StorageDriver.GetContent and
// StorageDriver.Reader.
Commit() error
// PathRegexp is the regular expression which each file path must match. A
// file path is absolute, beginning with a slash and containing a positive
// number of path components separated by slashes, where each component is
// restricted to alphanumeric characters or a period, underscore, or
// hyphen.
var PathRegexp = regexp.MustCompile(`^(/[A-Za-z0-9._-]+)+$`)
// ErrUnsupportedMethod may be returned in the case where a StorageDriver implementation does not support an optional method.
type ErrUnsupportedMethod struct {
DriverName string
func (err ErrUnsupportedMethod) Error() string {
return fmt.Sprintf("%s: unsupported method", err.DriverName)
// PathNotFoundError is returned when operating on a nonexistent path.
type PathNotFoundError struct {
Path string
DriverName string
func (err PathNotFoundError) Error() string {
return fmt.Sprintf("%s: Path not found: %s", err.DriverName, err.Path)
// InvalidPathError is returned when the provided path is malformed.
type InvalidPathError struct {
Path string
DriverName string
func (err InvalidPathError) Error() string {
return fmt.Sprintf("%s: invalid path: %s", err.DriverName, err.Path)
// InvalidOffsetError is returned when attempting to read or write from an
// invalid offset.
type InvalidOffsetError struct {
Path string
Offset int64
DriverName string
func (err InvalidOffsetError) Error() string {
return fmt.Sprintf("%s: invalid offset: %d for path: %s", err.DriverName, err.Offset, err.Path)
// Error is a catch-all error type which captures an error string and
// the driver type on which it occurred.
type Error struct {
DriverName string
Enclosed error
func (err Error) Error() string {
return fmt.Sprintf("%s: %s", err.DriverName, err.Enclosed)