net: merge FreeBSD and DragonFly sendfile support

The two files were identical except for comments.

Change-Id: Ifc300026c8e4584afa50a7b669099eaff146ea5d
Reviewed-on: https://go-review.googlesource.com/36631
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/sendfile_dragonfly.go → src/net/sendfile_bsd.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build dragonfly freebsd
+
 package net
 
 import (
@@ -22,10 +24,11 @@ const maxSendfileSize int = 4 << 20
 //
 // if handled == false, sendFile performed no work.
 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
-	// DragonFly uses 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.
+	// FreeBSD and DragonFly 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)
@@ -49,10 +52,11 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 		remain = fi.Size()
 	}
 
-	// The other quirk with DragonFly'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.
+	// The other quirk with FreeBSD/DragonFly'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

src/net/sendfile_freebsd.go

-// 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.
-
-package net
-
-import (
-	"io"
-	"os"
-	"syscall"
-)
-
-// maxSendfileSize is the largest chunk size we ask the kernel to copy
-// at a time.
-const maxSendfileSize int = 4 << 20
-
-// 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 uses 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'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
-	}
-
-	if err := c.writeLock(); err != nil {
-		return 0, err, true
-	}
-	defer c.writeUnlock()
-
-	dst := c.sysfd
-	src := int(f.Fd())
-	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)
-		}
-		if n == 0 && err1 == nil {
-			break
-		}
-		if err1 == syscall.EAGAIN {
-			if err1 = c.pd.waitWrite(); err1 == nil {
-				continue
-			}
-		}
-		if err1 == syscall.EINTR {
-			continue
-		}
-		if err1 != nil {
-			// This includes syscall.ENOSYS (no kernel
-			// support) and syscall.EINVAL (fd types which
-			// don't implement sendfile)
-			err = err1
-			break
-		}
-	}
-	if lr != nil {
-		lr.N = remain
-	}
-	if err != nil {
-		err = os.NewSyscallError("sendfile", err)
-	}
-	return written, err, written > 0
-}