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34 lines
839 B
Go
34 lines
839 B
Go
package iox
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import "io"
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// LimitTeeReader returns a Reader that writes up to n bytes to w what it reads from r.
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// First n bytes reads from r performed through it are matched with
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// corresponding writes to w. There is no internal buffering -
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// the write must complete before the first n bytes read completes.
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// Any error encountered while writing is reported as a read error.
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func LimitTeeReader(r io.Reader, w io.Writer, n int64) io.Reader {
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return &limitTeeReader{r, w, n}
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}
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type limitTeeReader struct {
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r io.Reader
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w io.Writer
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n int64 // limit bytes remaining
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}
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func (t *limitTeeReader) Read(p []byte) (n int, err error) {
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n, err = t.r.Read(p)
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if n > 0 && t.n > 0 {
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limit := int64(n)
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if limit > t.n {
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limit = t.n
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}
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if n, err := t.w.Write(p[:limit]); err != nil {
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return n, err
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}
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t.n -= limit
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}
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return
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}
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