// 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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// +build 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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"os"
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)
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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 of bytes copied and any
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// 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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// FreeBSD, DragonFly and Solaris use 0 as the "until EOF" value.
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// If you pass in more bytes than the file contains, it will
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// loop back to the beginning ad nauseam until it's sent
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// exactly the number of bytes told to. As such, we need to
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// know exactly how many bytes to send.
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var remain int64 = 0
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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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f, ok := r.(*os.File)
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if !ok {
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return 0, nil, false
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}
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if remain == 0 {
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fi, err := f.Stat()
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if err != nil {
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return 0, err, false
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}
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remain = fi.Size()
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}
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// The other quirk with FreeBSD/DragonFly/Solaris's sendfile
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// implementation is that it doesn't use the current position
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// of the file -- if you pass it offset 0, it starts from
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// offset 0. There's no way to tell it "start from current
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// position", so we have to manage that explicitly.
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pos, err := f.Seek(0, io.SeekCurrent)
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if err != nil {
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return 0, err, 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 = poll.SendFile(&c.pfd, int(fd), pos, remain)
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return true
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})
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if werr == nil {
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werr = err
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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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_, err1 := f.Seek(written, io.SeekCurrent)
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if err1 != nil && err == nil {
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return written, err1, written > 0
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}
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return written, wrapSyscallError("sendfile", err), written > 0
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}
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