syscall: use go generate to build zsyscall_windows.go

I would like to create new syscalls in src/internal/syscall,
and I prefer not to add new shell scripts for that.

Replacement for CL 136000043.

Change-Id: I840116b5914a2324f516cdb8603c78973d28aeb4
Reviewed-on: https://go-review.googlesource.com/1940Reviewed-by: Russ Cox <rsc@golang.org>

src/syscall/mkall.sh

@@ -244,9 +244,8 @@ solaris_amd64)
 	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
 	;;
 windows_*)
-	mksyscall=
-	mkerrors=
-	zerrors=
+	echo 'run "go generate syscall_windows.go" instead' 1>&2
+	exit 1
 	;;
 *)
 	echo 'unrecognized $GOOS_$GOARCH: ' "$GOOSARCH" 1>&2
@@ -256,22 +255,13 @@ esac
 
 (
 	if [ -n "$mkerrors" ]; then echo "$mkerrors |gofmt >$zerrors"; fi
-	case "$GOOS" in
-	windows)
-		echo "GOOS= GOARCH= go build mksyscall_windows.go"
-		echo "./mksyscall_windows syscall_windows.go security_windows.go |gofmt >zsyscall_windows.go"
-		echo "rm -f ./mksyscall_windows"
-		;;
-	*)
-		syscall_goos="syscall_$GOOS.go"
-		case "$GOOS" in
-		darwin | dragonfly | freebsd | netbsd | openbsd)
-			syscall_goos="syscall_bsd.go $syscall_goos"
-			;;
-		esac
-		if [ -n "$mksyscall" ]; then echo "$mksyscall $syscall_goos $GOOSARCH_in |gofmt >zsyscall_$GOOSARCH.go"; fi
-		;;
-	esac
+	syscall_goos="syscall_$GOOS.go"
+ 	case "$GOOS" in
+	darwin | dragonfly | freebsd | netbsd | openbsd)
+		syscall_goos="syscall_bsd.go $syscall_goos"
+ 		;;
+ 	esac
+	if [ -n "$mksyscall" ]; then echo "$mksyscall $syscall_goos syscall_$GOOSARCH.go |gofmt >zsyscall_$GOOSARCH.go"; fi
 	if [ -n "$mksysctl" ]; then echo "$mksysctl |gofmt >$zsysctl"; fi
 	if [ -n "$mksysnum" ]; then echo "$mksysnum |gofmt >zsysnum_$GOOSARCH.go"; fi
 	if [ -n "$mktypes" ]; then echo "$mktypes types_$GOOS.go |gofmt >ztypes_$GOOSARCH.go"; fi

src/syscall/mkall_windows.bat

-:: Copyright 2013 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.
-@echo off
-
-if exist mkall.sh goto dirok
-echo mkall_windows.bat must be run from src\syscall directory
-goto :end
-:dirok
-
-go build mksyscall_windows.go
-.\mksyscall_windows syscall_windows.go security_windows.go |gofmt >zsyscall_windows.go
-del mksyscall_windows.exe
-
-:end

src/syscall/mksyscall_windows.go

@@ -37,6 +37,8 @@ Usage:
 	mksyscall_windows [flags] [path ...]
 
 The flags are:
+	-output
+		Specify output file name (outputs to console if blank).
 	-trace
 		Generate print statement after every syscall.
 */
@@ -44,12 +46,15 @@ package main
 
 import (
 	"bufio"
+	"bytes"
 	"errors"
 	"flag"
 	"fmt"
+	"go/format"
 	"go/parser"
 	"go/token"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"strconv"
@@ -57,7 +62,10 @@ import (
 	"text/template"
 )
 
-var PrintTraceFlag = flag.Bool("trace", false, "generate print statement after every syscall")
+var (
+	filename       = flag.String("output", "", "output file name (standard output if omitted)")
+	printTraceFlag = flag.Bool("trace", false, "generate print statement after every syscall")
+)
 
 func trim(s string) string {
 	return strings.Trim(s, " \t")
@@ -379,7 +387,7 @@ func newFn(s string) (*Fn, error) {
 	f := &Fn{
 		Rets:       &Rets{},
 		src:        s,
-		PrintTrace: *PrintTraceFlag,
+		PrintTrace: *printTraceFlag,
 	}
 	// function name and args
 	prefix, body, s, found := extractSection(s, '(', ')')
@@ -669,8 +677,8 @@ func (src *Source) ParseFile(path string) error {
 // Generate output source file from a source set src.
 func (src *Source) Generate(w io.Writer) error {
 	funcMap := template.FuncMap{
-		"syscalldot":  syscalldot,
 		"packagename": packagename,
+		"syscalldot":  syscalldot,
 	}
 	t := template.Must(template.New("main").Funcs(funcMap).Parse(srcTemplate))
 	err := t.Execute(w, src)
@@ -689,15 +697,31 @@ func usage() {
 func main() {
 	flag.Usage = usage
 	flag.Parse()
-	if len(os.Args) <= 1 {
+	if len(flag.Args()) <= 0 {
 		fmt.Fprintf(os.Stderr, "no files to parse provided\n")
 		usage()
 	}
-	src, err := ParseFiles(os.Args[1:])
+
+	src, err := ParseFiles(flag.Args())
 	if err != nil {
 		log.Fatal(err)
 	}
-	if err := src.Generate(os.Stdout); err != nil {
+
+	var buf bytes.Buffer
+	if err := src.Generate(&buf); err != nil {
+		log.Fatal(err)
+	}
+
+	data, err := format.Source(buf.Bytes())
+	if err != nil {
+		log.Fatal(err)
+	}
+	if *filename == "" {
+		_, err = os.Stdout.Write(data)
+	} else {
+		err = ioutil.WriteFile(*filename, data, 0644)
+	}
+	if err != nil {
 		log.Fatal(err)
 	}
 }
@@ -705,8 +729,7 @@ func main() {
 // TODO: use println instead to print in the following template
 const srcTemplate = `
 
-{{define "main"}}// go build mksyscall_windows.go && ./mksyscall_windows{{range .Files}} {{.}}{{end}}
-// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+{{define "main"}}// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
 
 package {{packagename}}
 

src/syscall/syscall_windows.go

@@ -13,6 +13,8 @@ import (
 	"unsafe"
 )
 
+//go:generate go run mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go security_windows.go
+
 type Handle uintptr
 
 const InvalidHandle = ^Handle(0)

src/syscall/zsyscall_windows.go

-// go build mksyscall_windows.go && ./mksyscall_windows syscall_windows.go security_windows.go
-// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
 
 package syscall