Move to vendor

Signed-off-by: Olivier Gambier <olivier@docker.com>

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

@@ -0,0 +1,53 @@
+package sha256
+
+import (
+	"bytes"
+	"encoding/gob"
+
+	// 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)
+
+	// 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, d.is224,
+	}
+
+	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))
+
+	// 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, &d.is224,
+	}
+
+	for _, val := range vals {
+		if err := decoder.Decode(val); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}