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moby--moby/pkg/tarsum/versioning.go
Vincent Batts 747f89cd32 TarSum: versioning
This introduces Versions for TarSum checksums.
Fixes: https://github.com/docker/docker/issues/7526

It preserves current functionality and abstracts the interface for
future flexibility of hashing algorithms. As a POC, the VersionDev
Tarsum does not include the mtime in the checksum calculation, and would
solve https://github.com/docker/docker/issues/7387 though this is not a
settled Version is subject to change until a version number is assigned.

Signed-off-by: Vincent Batts <vbatts@redhat.com>
2014-09-10 15:41:52 -04:00

56 lines
1.2 KiB
Go

package tarsum
import (
"errors"
"strings"
)
// versioning of the TarSum algorithm
// based on the prefix of the hash used
// i.e. "tarsum+sha256:e58fcf7418d4390dec8e8fb69d88c06ec07039d651fedd3aa72af9972e7d046b"
type Version int
const (
// Prefix of "tarsum"
Version0 Version = iota
// Prefix of "tarsum.dev"
// NOTE: this variable will be of an unsettled next-version of the TarSum calculation
VersionDev
)
// Get a list of all known tarsum Version
func GetVersions() []Version {
v := []Version{}
for k := range tarSumVersions {
v = append(v, k)
}
return v
}
var tarSumVersions = map[Version]string{
0: "tarsum",
1: "tarsum.dev",
}
func (tsv Version) String() string {
return tarSumVersions[tsv]
}
// GetVersionFromTarsum returns the Version from the provided string
func GetVersionFromTarsum(tarsum string) (Version, error) {
tsv := tarsum
if strings.Contains(tarsum, "+") {
tsv = strings.SplitN(tarsum, "+", 2)[0]
}
for v, s := range tarSumVersions {
if s == tsv {
return v, nil
}
}
return -1, ErrNotVersion
}
var (
ErrNotVersion = errors.New("string does not include a TarSum Version")
ErrVersionNotImplemented = errors.New("TarSum Version is not yet implemented")
)