// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package poll
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import "syscall"
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// maxSendfileSize is the largest chunk size we ask the kernel to copy
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// at a time.
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const maxSendfileSize int = 4 << 20
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// SendFile wraps the sendfile system call.
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func SendFile(dstFD *FD, src int, remain int64) (int64, error) {
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if err := dstFD.writeLock(); err != nil {
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return 0, err
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}
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defer dstFD.writeUnlock()
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dst := int(dstFD.Sysfd)
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var written int64
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var err error
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for remain > 0 {
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n := maxSendfileSize
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if int64(n) > remain {
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n = int(remain)
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}
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n, err1 := syscall.Sendfile(dst, src, nil, n)
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if n > 0 {
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written += int64(n)
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remain -= int64(n)
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} else if n == 0 && err1 == nil {
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break
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}
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if err1 == syscall.EAGAIN {
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if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil {
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continue
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}
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}
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if err1 != nil {
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// This includes syscall.ENOSYS (no kernel
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// support) and syscall.EINVAL (fd types which
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// don't implement sendfile)
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err = err1
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break
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}
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}
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return written, err
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}
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