distribution/registry/storage/driver/storagedriver.go

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package driver
import (
"errors"
"fmt"
"io"
"regexp"
"strconv"
"strings"
)
// 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.
type StorageDriver interface {
// GetContent retrieves the content stored at "path" as a []byte.
// This should primarily be used for small objects.
GetContent(path string) ([]byte, error)
// PutContent stores the []byte content at a location designated by "path".
// This should primarily be used for small objects.
PutContent(path string, content []byte) error
// ReadStream 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.
ReadStream(path string, offset int64) (io.ReadCloser, error)
// WriteStream stores the contents of the provided io.ReadCloser at a
// location designated by the given path.
// May be used to resume writing a stream by providing a nonzero offset.
// The offset must be no larger than the CurrentSize for this path.
WriteStream(path string, offset int64, reader io.Reader) (nn int64, err error)
// Stat retrieves the FileInfo for the given path, including the current
// size in bytes and the creation time.
Stat(path string) (FileInfo, error)
// List returns a list of the objects that are direct descendants of the
//given path.
List(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(sourcePath string, destPath string) error
// Delete recursively deletes all objects stored at "path" and its subpaths.
Delete(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 UnsupportedMethodErr in certain StorageDriver
// implementations.
URLFor(path string, options map[string]interface{}) (string, 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 lowercase alphanumeric characters or a period, underscore, or
// hyphen.
var PathRegexp = regexp.MustCompile(`^(/[a-z0-9._-]+)+$`)
// UnsupportedMethodErr may be returned in the case where a StorageDriver implementation does not support an optional method.
var ErrUnsupportedMethod = errors.New("Unsupported method")
// PathNotFoundError is returned when operating on a nonexistent path.
type PathNotFoundError struct {
Path string
}
func (err PathNotFoundError) Error() string {
return fmt.Sprintf("Path not found: %s", err.Path)
}
// InvalidPathError is returned when the provided path is malformed.
type InvalidPathError struct {
Path string
}
func (err InvalidPathError) Error() string {
return fmt.Sprintf("Invalid path: %s", err.Path)
}
// InvalidOffsetError is returned when attempting to read or write from an
// invalid offset.
type InvalidOffsetError struct {
Path string
Offset int64
}
func (err InvalidOffsetError) Error() string {
return fmt.Sprintf("Invalid offset: %d for path: %s", err.Offset, err.Path)
}