1// Copyright 2011 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// +build hurd linux 6 7package poll 8 9import "syscall" 10 11// maxSendfileSize is the largest chunk size we ask the kernel to copy 12// at a time. 13const maxSendfileSize int = 4 << 20 14 15// SendFile wraps the sendfile system call. 16func SendFile(dstFD *FD, src int, remain int64) (int64, error) { 17 if err := dstFD.writeLock(); err != nil { 18 return 0, err 19 } 20 defer dstFD.writeUnlock() 21 if err := dstFD.pd.prepareWrite(dstFD.isFile); err != nil { 22 return 0, err 23 } 24 25 dst := int(dstFD.Sysfd) 26 var written int64 27 var err error 28 for remain > 0 { 29 n := maxSendfileSize 30 if int64(n) > remain { 31 n = int(remain) 32 } 33 n, err1 := syscall.Sendfile(dst, src, nil, n) 34 if n > 0 { 35 written += int64(n) 36 remain -= int64(n) 37 } else if n == 0 && err1 == nil { 38 break 39 } 40 if err1 == syscall.EINTR { 41 continue 42 } 43 if err1 == syscall.EAGAIN { 44 if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil { 45 continue 46 } 47 } 48 if err1 != nil { 49 // This includes syscall.ENOSYS (no kernel 50 // support) and syscall.EINVAL (fd types which 51 // don't implement sendfile) 52 err = err1 53 break 54 } 55 } 56 return written, err 57} 58