mirror of https://github.com/golang/go.git
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
// 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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//go:build (darwin && !ios) || dragonfly || freebsd || solaris
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package net
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import (
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"internal/poll"
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"io"
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"syscall"
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)
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const supportsSendfile = true
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// sendFile copies the contents of r to c using the sendfile
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// system call to minimize copies.
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//
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// if handled == true, sendFile returns the number (potentially zero) of bytes
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// copied and any non-EOF error.
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//
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// if handled == false, sendFile performed no work.
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func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
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var remain int64 = 0 // 0 writes the entire file
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lr, ok := r.(*io.LimitedReader)
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if ok {
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remain, r = lr.N, lr.R
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if remain <= 0 {
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return 0, nil, true
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}
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}
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// r might be an *os.File or an os.fileWithoutWriteTo.
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// Type assert to an interface rather than *os.File directly to handle the latter case.
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f, ok := r.(syscall.Conn)
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if !ok {
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return 0, nil, false
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}
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sc, err := f.SyscallConn()
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if err != nil {
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return 0, nil, false
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}
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var werr error
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err = sc.Read(func(fd uintptr) bool {
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written, werr, handled = poll.SendFile(&c.pfd, int(fd), remain)
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return true
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})
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if err == nil {
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err = werr
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}
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if lr != nil {
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lr.N = remain - written
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}
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return written, wrapSyscallError("sendfile", err), handled
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}
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