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 }