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- // Copyright 2011 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- //go:build (darwin && !ios) || dragonfly || freebsd || solaris
- package net
- import (
- "internal/poll"
- "io"
- "os"
- )
- // sendFile copies the contents of r to c using the sendfile
- // system call to minimize copies.
- //
- // if handled == true, sendFile returns the number of bytes copied and any
- // non-EOF error.
- //
- // if handled == false, sendFile performed no work.
- func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
- // FreeBSD, DragonFly and Solaris use 0 as the "until EOF" value.
- // If you pass in more bytes than the file contains, it will
- // loop back to the beginning ad nauseam until it's sent
- // exactly the number of bytes told to. As such, we need to
- // know exactly how many bytes to send.
- var remain int64 = 0
- lr, ok := r.(*io.LimitedReader)
- if ok {
- remain, r = lr.N, lr.R
- if remain <= 0 {
- return 0, nil, true
- }
- }
- f, ok := r.(*os.File)
- if !ok {
- return 0, nil, false
- }
- if remain == 0 {
- fi, err := f.Stat()
- if err != nil {
- return 0, err, false
- }
- remain = fi.Size()
- }
- // The other quirk with FreeBSD/DragonFly/Solaris's sendfile
- // implementation is that it doesn't use the current position
- // of the file -- if you pass it offset 0, it starts from
- // offset 0. There's no way to tell it "start from current
- // position", so we have to manage that explicitly.
- pos, err := f.Seek(0, io.SeekCurrent)
- if err != nil {
- return 0, err, false
- }
- sc, err := f.SyscallConn()
- if err != nil {
- return 0, nil, false
- }
- var werr error
- err = sc.Read(func(fd uintptr) bool {
- written, werr = poll.SendFile(&c.pfd, int(fd), pos, remain)
- return true
- })
- if err == nil {
- err = werr
- }
- if lr != nil {
- lr.N = remain - written
- }
- _, err1 := f.Seek(written, io.SeekCurrent)
- if err1 != nil && err == nil {
- return written, err1, written > 0
- }
- return written, wrapSyscallError("sendfile", err), written > 0
- }
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