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// Copyright 2019 the u-root 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 uio
import (
"bytes"
"io"
)
// AlignWriter keeps track of how many bytes were written so the writer can be
// aligned at a future time.
type AlignWriter struct {
W io.Writer
N int
}
// Write writes to the underlying io.Writew.
func (w *AlignWriter) Write(b []byte) (int, error) {
n, err := w.W.Write(b)
w.N += n
return n, err
}
// Align aligns the writer to the given number of bytes using the given pad
// value.
func (w *AlignWriter) Align(n int, pad byte) error {
if w.N%n == 0 {
return nil
}
_, err := w.Write(bytes.Repeat([]byte{pad}, n-w.N%n))
return err
}
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