| // 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. |
| |
| // +build dragonfly freebsd |
| |
| package poll |
| |
| import "syscall" |
| |
| // maxSendfileSize is the largest chunk size we ask the kernel to copy |
| // at a time. |
| const maxSendfileSize int = 4 << 20 |
| |
| // SendFile wraps the sendfile system call. |
| func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) { |
| if err := dstFD.writeLock(); err != nil { |
| return 0, err |
| } |
| defer dstFD.writeUnlock() |
| if err := dstFD.pd.prepareWrite(dstFD.isFile); err != nil { |
| return 0, err |
| } |
| |
| dst := int(dstFD.Sysfd) |
| var written int64 |
| var err error |
| for remain > 0 { |
| n := maxSendfileSize |
| if int64(n) > remain { |
| n = int(remain) |
| } |
| pos1 := pos |
| n, err1 := syscall.Sendfile(dst, src, &pos1, n) |
| if n > 0 { |
| pos += int64(n) |
| written += int64(n) |
| remain -= int64(n) |
| } else if n == 0 && err1 == nil { |
| break |
| } |
| if err1 == syscall.EINTR { |
| continue |
| } |
| if err1 == syscall.EAGAIN { |
| if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil { |
| continue |
| } |
| } |
| if err1 != nil { |
| // This includes syscall.ENOSYS (no kernel |
| // support) and syscall.EINVAL (fd types which |
| // don't implement sendfile) |
| err = err1 |
| break |
| } |
| } |
| return written, err |
| } |