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// Copyright ©2011-2012 The bíogo Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package util
import (
"errors"
"hash"
"io"
"os"
)
const (
bufferLen = 1 << 15
)
var buffer = make([]byte, bufferLen)
// Hash returns the h hash sum of file f and any error. The hash is not reset on return,
// so if individual files are to be hashed with the same h, it should be reset.
func Hash(h hash.Hash, f *os.File) (sum []byte, err error) {
fi, err := f.Stat()
if err != nil || fi.IsDir() {
return nil, errors.New("util: file is a directory")
}
s := io.NewSectionReader(f, 0, fi.Size())
for n, buffer := 0, make([]byte, bufferLen); err == nil; {
n, err = s.Read(buffer)
h.Write(buffer[:n])
}
if err == io.EOF {
err = nil
}
sum = h.Sum(nil)
return
}
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