distribution/vendor/github.com/stevvooe/resumable/sha256/resume.go

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package sha256
import (
"bytes"
"crypto"
"encoding/gob"
"github.com/stevvooe/resumable"
// import to ensure that our init function runs after the standard package
_ "crypto/sha256"
)
// Len returns the number of bytes which have been written to the digest.
func (d *digest) Len() int64 {
return int64(d.len)
}
// State returns a snapshot of the state of the digest.
func (d *digest) State() ([]byte, error) {
var buf bytes.Buffer
encoder := gob.NewEncoder(&buf)
function := crypto.SHA256
if d.is224 {
function = crypto.SHA224
}
// We encode this way so that we do not have
// to export these fields of the digest struct.
vals := []interface{}{
d.h, d.x, d.nx, d.len, function,
}
for _, val := range vals {
if err := encoder.Encode(val); err != nil {
return nil, err
}
}
return buf.Bytes(), nil
}
// Restore resets the digest to the given state.
func (d *digest) Restore(state []byte) error {
decoder := gob.NewDecoder(bytes.NewReader(state))
var function uint
// We decode this way so that we do not have
// to export these fields of the digest struct.
vals := []interface{}{
&d.h, &d.x, &d.nx, &d.len, &function,
}
for _, val := range vals {
if err := decoder.Decode(val); err != nil {
return err
}
}
switch crypto.Hash(function) {
case crypto.SHA224:
d.is224 = true
case crypto.SHA256:
d.is224 = false
default:
return resumable.ErrBadState
}
return nil
}