libgo/go/internal/poll/sendfile_bsd.go

   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 dragonfly freebsd
   6
   7 package poll
   8
   9 import "syscall"
  10
  11 // maxSendfileSize is the largest chunk size we ask the kernel to copy
  12 // at a time.
  13 const maxSendfileSize int = 4 << 20
  14
  15 // SendFile wraps the sendfile system call.
  16 func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
  17         if err := dstFD.writeLock(); err != nil {
  18                 return 0, err
  19         }
  20         defer dstFD.writeUnlock()
  21         dst := int(dstFD.Sysfd)
  22         var written int64
  23         var err error
  24         for remain > 0 {
  25                 n := maxSendfileSize
  26                 if int64(n) > remain {
  27                         n = int(remain)
  28                 }
  29                 pos1 := pos
  30                 n, err1 := syscall.Sendfile(dst, src, &pos1, n)
  31                 if n > 0 {
  32                         pos += int64(n)
  33                         written += int64(n)
  34                         remain -= int64(n)
  35                 }
  36                 if n == 0 && err1 == nil {
  37                         break
  38                 }
  39                 if err1 == syscall.EAGAIN {
  40                         if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil {
  41                                 continue
  42                         }
  43                 }
  44                 if err1 != nil {
  45                         // This includes syscall.ENOSYS (no kernel
  46                         // support) and syscall.EINVAL (fd types which
  47                         // don't implement sendfile)
  48                         err = err1
  49                         break
  50                 }
  51         }
  52         return written, err
  53 }