net: Sendfile for win32.

implement using TransmitFile().

R=bsiegert, bradfitz, alex.brainman, rsc, go.peter.90
CC=golang-dev
https://golang.org/cl/4536076

src/pkg/net/Makefile

@@ -82,7 +82,7 @@ GOFILES_windows=\
 	file_windows.go\
 	interface_stub.go\
 	resolv_windows.go\
-	sendfile_stub.go\
+	sendfile_windows.go\
 	sock_windows.go\
 
 GOFILES+=$(GOFILES_$(GOOS))

src/pkg/net/sendfile_windows.go

@@ -0,0 +1,68 @@
+// 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"
+)
+
+type sendfileOp struct {
+	anOp
+	src int32 // source
+	n   uint32
+}
+
+func (o *sendfileOp) Submit() (errno int) {
+	return syscall.TransmitFile(int32(o.fd.sysfd), o.src, o.n, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
+}
+
+func (o *sendfileOp) Name() string {
+	return "TransmitFile"
+}
+
+// sendFile copies the contents of r to c using the TransmitFile
+// 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.
+//
+// Note that sendfile for windows does not suppport >2GB file.
+func sendFile(c *netFD, r io.Reader) (written int64, err os.Error, handled bool) {
+	var n int64 = 0 // by default, copy until EOF
+
+	lr, ok := r.(*io.LimitedReader)
+	if ok {
+		n, r = lr.N, lr.R
+		if n <= 0 {
+			return 0, nil, true
+		}
+	}
+	f, ok := r.(*os.File)
+	if !ok {
+		return 0, nil, false
+	}
+
+	c.wio.Lock()
+	defer c.wio.Unlock()
+	c.incref()
+	defer c.decref()
+
+	var o sendfileOp
+	o.Init(c)
+	o.n = uint32(n)
+	o.src = int32(f.Fd())
+	done, err := iosrv.ExecIO(&o, 0)
+	if err != nil {
+		return 0, err, false
+	}
+	if lr != nil {
+		lr.N -= int64(done)
+	}
+	return int64(done), nil, true
+}

src/pkg/syscall/syscall_windows.go

@@ -173,6 +173,7 @@ func Sendfile(outfd int, infd int, offset *int64, count int) (written int, errno
 //sys	FlushViewOfFile(addr uintptr, length uintptr) (errno int)
 //sys	VirtualLock(addr uintptr, length uintptr) (errno int)
 //sys	VirtualUnlock(addr uintptr, length uintptr) (errno int)
+//sys	TransmitFile(s int32, handle int32, bytesToWrite uint32, bytsPerSend uint32, overlapped *Overlapped, transmitFileBuf *TransmitFileBuffers, flags uint32) (errno int) = wsock32.TransmitFile
 
 // syscall interface implementation for other packages
 

src/pkg/syscall/zsyscall_windows_386.go

@@ -77,6 +77,7 @@ var (
 	procFlushViewOfFile            = getSysProcAddr(modkernel32, "FlushViewOfFile")
 	procVirtualLock                = getSysProcAddr(modkernel32, "VirtualLock")
 	procVirtualUnlock              = getSysProcAddr(modkernel32, "VirtualUnlock")
+	procTransmitFile               = getSysProcAddr(modwsock32, "TransmitFile")
 	procWSAStartup                 = getSysProcAddr(modwsock32, "WSAStartup")
 	procWSACleanup                 = getSysProcAddr(modwsock32, "WSACleanup")
 	procsocket                     = getSysProcAddr(modwsock32, "socket")
@@ -1008,6 +1009,20 @@ func VirtualUnlock(addr uintptr, length uintptr) (errno int) {
 	return
 }
 
+func TransmitFile(s int32, handle int32, bytesToWrite uint32, bytsPerSend uint32, overlapped *Overlapped, transmitFileBuf *TransmitFileBuffers, flags uint32) (errno int) {
+	r1, _, e1 := Syscall9(procTransmitFile, 7, uintptr(s), uintptr(handle), uintptr(bytesToWrite), uintptr(bytsPerSend), uintptr(unsafe.Pointer(overlapped)), uintptr(unsafe.Pointer(transmitFileBuf)), uintptr(flags), 0, 0)
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func WSAStartup(verreq uint32, data *WSAData) (sockerrno int) {
 	r0, _, _ := Syscall(procWSAStartup, 2, uintptr(verreq), uintptr(unsafe.Pointer(data)), 0)
 	sockerrno = int(r0)

src/pkg/syscall/ztypes_windows_386.go

@@ -545,3 +545,19 @@ type DNSRecord struct {
 	Reserved uint32
 	Data     [40]byte
 }
+
+const (
+	TF_DISCONNECT         = 1
+	TF_REUSE_SOCKET       = 2
+	TF_WRITE_BEHIND       = 4
+	TF_USE_DEFAULT_WORKER = 0
+	TF_USE_SYSTEM_THREAD  = 16
+	TF_USE_KERNEL_APC     = 32
+)
+
+type TransmitFileBuffers struct {
+	Head       uintptr
+	HeadLength uint32
+	Tail       uintptr
+	TailLength uint32
+}