27 lines
854 B
Go
27 lines
854 B
Go
package meta
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import "io"
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// readBuf is the local buffer used by readBytes.
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var readBuf = make([]byte, 4096)
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// readBytes reads and returns exactly n bytes from the provided io.Reader. The
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// local buffer is reused in between calls to reduce garbage generation. It is
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// the callers responsibility to make a copy of the returned data. The error is
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// io.EOF only if no bytes were read. If an io.EOF happens after reading some
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// but not all the bytes, ReadFull returns io.ErrUnexpectedEOF. On return, n ==
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// len(buf) if and only if err == nil.
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//
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// The local buffer is initially 4096 bytes and will grow automatically if so
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// required.
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func readBytes(r io.Reader, n int) ([]byte, error) {
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if n > len(readBuf) {
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readBuf = make([]byte, n)
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}
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_, err := io.ReadFull(r, readBuf[:n])
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if err != nil {
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return nil, err
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}
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return readBuf[:n:n], nil
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}
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