distribution/digest/digester_resumable.go
Andy Goldstein 7fdd395653 Use a build flag to disable resumable digests.
Signed-off-by: Andy Goldstein <agoldste@redhat.com>
2015-04-16 01:19:57 +00:00

52 lines
1.3 KiB
Go

// +build !noresumabledigest
package digest
import (
"fmt"
"github.com/jlhawn/go-crypto"
// For ResumableHash
_ "github.com/jlhawn/go-crypto/sha256" // For Resumable SHA256
_ "github.com/jlhawn/go-crypto/sha512" // For Resumable SHA384, SHA512
)
// resumableDigester implements ResumableDigester.
type resumableDigester struct {
alg string
crypto.ResumableHash
}
var resumableHashAlgs = map[string]crypto.Hash{
"sha256": crypto.SHA256,
"sha384": crypto.SHA384,
"sha512": crypto.SHA512,
}
// NewResumableDigester creates a new ResumableDigester with the given hashing
// algorithm.
func NewResumableDigester(alg string) (ResumableDigester, error) {
hash, supported := resumableHashAlgs[alg]
if !supported {
return resumableDigester{}, fmt.Errorf("unsupported resumable hash algorithm: %s", alg)
}
return resumableDigester{
alg: alg,
ResumableHash: hash.New(),
}, nil
}
// NewCanonicalResumableDigester creates a ResumableDigester using the default
// digest algorithm.
func NewCanonicalResumableDigester() ResumableDigester {
return resumableDigester{
alg: "sha256",
ResumableHash: crypto.SHA256.New(),
}
}
// Digest returns the current digest for this resumable digester.
func (d resumableDigester) Digest() Digest {
return NewDigest(d.alg, d.ResumableHash)
}