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38 lines
736 B
Go
38 lines
736 B
Go
package utils
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import (
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"errors"
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"io"
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)
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// LimitedReader implements io.Reader, but you can only read the given number of bytes
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type LimitedReader struct {
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src io.Reader
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n int
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limit int
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}
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// NewLimitedReader wraps an io.Reader to LimitedReader
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func NewLimitedReader(src io.Reader, limit int) *LimitedReader {
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return &LimitedReader{
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src: src,
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limit: limit,
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}
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}
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// Read reads up to len(p) bytes into p. if meets EOF from src or reach limit, it returns EOF
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func (r *LimitedReader) Read(p []byte) (n int, err error) {
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if r.src == nil {
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return 0, errors.New("no data source")
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}
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if r.limit > 0 && r.n >= r.limit {
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return 0, io.EOF
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}
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n, err = r.src.Read(p)
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if err != nil {
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return n, err
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}
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r.n += n
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return
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}
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