restic/hashing.go

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2014-07-28 18:20:32 +00:00
package khepri
import (
"hash"
"io"
)
// HashingReader is the interfaces that wraps a normal reader. When Hash() is called,
// it returns the hash for all data that has been read so far.
type HashingReader interface {
io.Reader
Hash() []byte
}
// HashingWriter is the interfaces that wraps a normal writer. When Hash() is called,
// it returns the hash for all data that has been written so far.
type HashingWriter interface {
io.Writer
Hash() []byte
}
type reader struct {
reader io.Reader
hash hash.Hash
}
// NewHashingReader wraps an io.Reader and in addition feeds all data read through the
// given hash.
func NewHashingReader(r io.Reader, h func() hash.Hash) *reader {
return &reader{
reader: r,
hash: h(),
}
}
func (h *reader) Read(p []byte) (int, error) {
// call original reader
n, err := h.reader.Read(p)
// hash bytes
if n > 0 {
// hash
h.hash.Write(p[0:n])
}
// return result
return n, err
}
func (h *reader) Hash() []byte {
return h.hash.Sum([]byte{})
}
type writer struct {
writer io.Writer
hash hash.Hash
}
// NewHashingWriter wraps an io.Reader and in addition feeds all data written through
// the given hash.
func NewHashingWriter(w io.Writer, h func() hash.Hash) *writer {
return &writer{
writer: w,
hash: h(),
}
}
func (h *writer) Write(p []byte) (int, error) {
// call original writer
n, err := h.writer.Write(p)
// hash bytes
if n > 0 {
// hash
h.hash.Write(p[0:n])
}
// return result
return n, err
}
func (h *writer) Hash() []byte {
return h.hash.Sum([]byte{})
}