57 lines
921 B
Go
57 lines
921 B
Go
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package iio
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import (
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"errors"
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"io"
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"io/ioutil"
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"sync"
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)
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type readAtWrapper struct {
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mu sync.Mutex
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io.ReadSeeker
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io.ReaderAt
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}
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func NewReadAtWrapper(r io.ReadSeeker) io.ReaderAt {
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return &readAtWrapper{ReadSeeker: r}
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}
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func (rw *readAtWrapper) ReadAt(p []byte, off int64) (int, error) {
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rw.mu.Lock()
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defer rw.mu.Unlock()
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_, err := rw.Seek(off, io.SeekStart)
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if err != nil {
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return 0, err
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}
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return rw.Read(p)
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}
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type unbufferedReaderAt struct {
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io.Reader
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N int64
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}
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func NewUnbufferedReaderAt(r io.Reader) io.ReaderAt {
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return &unbufferedReaderAt{Reader: r}
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}
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// TODO not working properly
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func (u *unbufferedReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
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if off < u.N {
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return 0, errors.New("invalid offset")
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}
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diff := off - u.N
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written, err := io.CopyN(ioutil.Discard, u, diff)
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u.N += written
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if err != nil {
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return 0, err
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}
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n, err = u.Read(p)
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u.N += int64(n)
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return
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}
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