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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2016 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package osutil
import (
"crypto"
"io"
"os"
)
const (
hashDigestBufSize = 2 * 1024 * 1024
)
// FileDigest computes a hash digest of the file using the given hash.
// It also returns the file size.
func FileDigest(filename string, hash crypto.Hash) ([]byte, uint64, error) {
f, err := os.Open(filename)
if err != nil {
return nil, 0, err
}
defer f.Close()
h := hash.New()
size, err := io.CopyBuffer(h, f, make([]byte, hashDigestBufSize))
if err != nil {
return nil, 0, err
}
return h.Sum(nil), uint64(size), nil
}
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