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// Copyright 2014 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package hash
import (
"encoding/base64"
"hash"
"io"
)
// TODO(ericsnow) Remove HashingWriter and NewHashingWriter().
// HashingWriter wraps an io.Writer, providing the checksum of all data
// written to it. A HashingWriter may be used in place of the writer it
// wraps.
//
// Note: HashingWriter is deprecated. Please do not use it. We will
// remove it ASAP.
type HashingWriter struct {
hash hash.Hash
wrapped io.Writer
}
// NewHashingWriter returns a new HashingWriter that wraps the provided
// writer and the hasher.
//
// Example:
// hw := NewHashingWriter(w, sha1.New())
// io.Copy(hw, reader)
// hash := hw.Base64Sum()
//
// Note: NewHashingWriter is deprecated. Please do not use it. We will
// remove it ASAP.
func NewHashingWriter(writer io.Writer, hasher hash.Hash) *HashingWriter {
return &HashingWriter{
hash: hasher,
wrapped: io.MultiWriter(writer, hasher),
}
}
// Base64Sum returns the base64 encoded hash.
func (hw HashingWriter) Base64Sum() string {
sumBytes := hw.hash.Sum(nil)
return base64.StdEncoding.EncodeToString(sumBytes)
}
// Write writes to both the wrapped file and the hash.
func (hw *HashingWriter) Write(data []byte) (int, error) {
// No trace because some callers, like ioutil.ReadAll(), won't work.
return hw.wrapped.Write(data)
}
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