kopia lustrzana https://github.com/jcs/id3-go
60 wiersze
1016 B
Go
60 wiersze
1016 B
Go
// Copyright 2013 Michael Yang. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package id3
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import (
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"io"
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"os"
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)
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func shiftBytesBack(file *os.File, start, offset int64) error {
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stat, err := file.Stat()
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if err != nil {
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return err
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}
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end := stat.Size()
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wrBuf := make([]byte, offset)
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rdBuf := make([]byte, offset)
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wrOffset := offset
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rdOffset := start
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rn, err := file.ReadAt(wrBuf, rdOffset)
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if err != nil && err != io.EOF {
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panic(err)
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}
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rdOffset += int64(rn)
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for {
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if rdOffset >= end {
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break
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}
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n, err := file.ReadAt(rdBuf, rdOffset)
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if err != nil && err != io.EOF {
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return err
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}
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if rdOffset+int64(n) > end {
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n = int(end - rdOffset)
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}
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if _, err := file.WriteAt(wrBuf[:rn], wrOffset); err != nil {
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return err
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}
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rdOffset += int64(n)
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wrOffset += int64(rn)
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copy(wrBuf, rdBuf)
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rn = n
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}
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if _, err := file.WriteAt(wrBuf[:rn], wrOffset); err != nil {
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return err
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}
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return nil
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}
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