42 lines
1.0 KiB
Go
42 lines
1.0 KiB
Go
package iox
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import (
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`io`
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)
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/*
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CopyBufN is a mix between io.CopyN and io.CopyBuffer.
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Despite what the docs may suggest, io.CopyN does NOT *read* n bytes from src AND write n bytes to dst.
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Instead, it always reads 32 KiB from src, and writes n bytes to dst.
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There are, of course, cases where this is deadfully undesired.
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One can, of course, use io.CopyBuffer, but this is a bit annoying since you then have to provide a buffer yourself.
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This convenience-wraps io.CopyBuffer to have a similar signature to io.CopyN but properly uses n for both reading and writing.
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*/
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func CopyBufN(dst io.Writer, src io.Reader, n int64) (written int64, err error) {
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var b []byte
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if n <= 0 {
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err = ErrBufTooSmall
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return
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}
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b = make([]byte, n)
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written, err = io.CopyBuffer(dst, src, b)
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return
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}
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// CopyBufWith allows for specifying a buffer allocator function, otherwise acts as CopyBufN.
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func CopyBufWith(dst io.Writer, src io.Reader, bufFunc func() (b []byte)) (written int64, err error) {
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written, err = io.CopyBuffer(dst, src, bufFunc())
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return
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}
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