distribution/digest/digester.go
David Lawrence b777e389b9 fixing up tests to work with for non-tarsum future
Signed-off-by: David Lawrence <david.lawrence@docker.com> (github: endophage)
2015-03-06 14:54:23 -08:00

44 lines
1 KiB
Go

package digest
import (
"crypto/sha256"
"hash"
)
// Digester calculates the digest of written data. It is functionally
// equivalent to hash.Hash but provides methods for returning the Digest type
// rather than raw bytes.
type Digester struct {
alg string
hash hash.Hash
}
// NewDigester create a new Digester with the given hashing algorithm and instance
// of that algo's hasher.
func NewDigester(alg string, h hash.Hash) Digester {
return Digester{
alg: alg,
hash: h,
}
}
// NewCanonicalDigester is a convenience function to create a new Digester with
// out default settings.
func NewCanonicalDigester() Digester {
return NewDigester("sha256", sha256.New())
}
// Write data to the digester. These writes cannot fail.
func (d *Digester) Write(p []byte) (n int, err error) {
return d.hash.Write(p)
}
// Digest returns the current digest for this digester.
func (d *Digester) Digest() Digest {
return NewDigest(d.alg, d.hash)
}
// Reset the state of the digester.
func (d *Digester) Reset() {
d.hash.Reset()
}