Use mksyscall_windows.go from $GOROOT

extras/mksyscall_windows.go

@@ -1,871 +0,0 @@
-// 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.
-
-// +build ignore
-
-/*
-mksyscall_windows generates windows system call bodies
-
-It parses all files specified on command line containing function
-prototypes (like syscall_windows.go) and prints system call bodies
-to standard output.
-
-The prototypes are marked by lines beginning with "//sys" and read
-like func declarations if //sys is replaced by func, but:
-
-* The parameter lists must give a name for each argument. This
-  includes return parameters.
-
-* The parameter lists must give a type for each argument:
-  the (x, y, z int) shorthand is not allowed.
-
-* If the return parameter is an error number, it must be named err.
-
-* If go func name needs to be different from it's winapi dll name,
-  the winapi name could be specified at the end, after "=" sign, like
-  //sys LoadLibrary(libname string) (handle uint32, err error) = LoadLibraryA
-
-* Each function that returns err needs to supply a condition, that
-  return value of winapi will be tested against to detect failure.
-  This would set err to windows "last-error", otherwise it will be nil.
-  The value can be provided at end of //sys declaration, like
-  //sys LoadLibrary(libname string) (handle uint32, err error) [failretval==-1] = LoadLibraryA
-  and is [failretval==0] by default.
-
-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.
-*/
-package main
-
-import (
-	"bufio"
-	"bytes"
-	"errors"
-	"flag"
-	"fmt"
-	"go/format"
-	"go/parser"
-	"go/token"
-	"io"
-	"io/ioutil"
-	"log"
-	"os"
-	"path/filepath"
-	"runtime"
-	"sort"
-	"strconv"
-	"strings"
-	"text/template"
-)
-
-var (
-	filename       = flag.String("output", "", "output file name (standard output if omitted)")
-	printTraceFlag = flag.Bool("trace", false, "generate print statement after every syscall")
-	systemDLL      = flag.Bool("systemdll", true, "whether all DLLs should be loaded from the Windows system directory")
-)
-
-func trim(s string) string {
-	return strings.Trim(s, " \t")
-}
-
-var packageName string
-
-func packagename() string {
-	return packageName
-}
-
-func syscalldot() string {
-	if packageName == "syscall" {
-		return ""
-	}
-	return "syscall."
-}
-
-// Param is function parameter
-type Param struct {
-	Name      string
-	Type      string
-	fn        *Fn
-	tmpVarIdx int
-}
-
-// tmpVar returns temp variable name that will be used to represent p during syscall.
-func (p *Param) tmpVar() string {
-	if p.tmpVarIdx < 0 {
-		p.tmpVarIdx = p.fn.curTmpVarIdx
-		p.fn.curTmpVarIdx++
-	}
-	return fmt.Sprintf("_p%d", p.tmpVarIdx)
-}
-
-// BoolTmpVarCode returns source code for bool temp variable.
-func (p *Param) BoolTmpVarCode() string {
-	const code = `var %s uint32
-	if %s {
-		%s = 1
-	} else {
-		%s = 0
-	}`
-	tmp := p.tmpVar()
-	return fmt.Sprintf(code, tmp, p.Name, tmp, tmp)
-}
-
-// SliceTmpVarCode returns source code for slice temp variable.
-func (p *Param) SliceTmpVarCode() string {
-	const code = `var %s *%s
-	if len(%s) > 0 {
-		%s = &%s[0]
-	}`
-	tmp := p.tmpVar()
-	return fmt.Sprintf(code, tmp, p.Type[2:], p.Name, tmp, p.Name)
-}
-
-// StringTmpVarCode returns source code for string temp variable.
-func (p *Param) StringTmpVarCode() string {
-	errvar := p.fn.Rets.ErrorVarName()
-	if errvar == "" {
-		errvar = "_"
-	}
-	tmp := p.tmpVar()
-	const code = `var %s %s
-	%s, %s = %s(%s)`
-	s := fmt.Sprintf(code, tmp, p.fn.StrconvType(), tmp, errvar, p.fn.StrconvFunc(), p.Name)
-	if errvar == "-" {
-		return s
-	}
-	const morecode = `
-	if %s != nil {
-		return
-	}`
-	return s + fmt.Sprintf(morecode, errvar)
-}
-
-// TmpVarCode returns source code for temp variable.
-func (p *Param) TmpVarCode() string {
-	switch {
-	case p.Type == "bool":
-		return p.BoolTmpVarCode()
-	case strings.HasPrefix(p.Type, "[]"):
-		return p.SliceTmpVarCode()
-	default:
-		return ""
-	}
-}
-
-// TmpVarHelperCode returns source code for helper's temp variable.
-func (p *Param) TmpVarHelperCode() string {
-	if p.Type != "string" {
-		return ""
-	}
-	return p.StringTmpVarCode()
-}
-
-// SyscallArgList returns source code fragments representing p parameter
-// in syscall. Slices are translated into 2 syscall parameters: pointer to
-// the first element and length.
-func (p *Param) SyscallArgList() []string {
-	t := p.HelperType()
-	var s string
-	switch {
-	case t[0] == '*':
-		s = fmt.Sprintf("unsafe.Pointer(%s)", p.Name)
-	case t == "bool":
-		s = p.tmpVar()
-	case strings.HasPrefix(t, "[]"):
-		return []string{
-			fmt.Sprintf("uintptr(unsafe.Pointer(%s))", p.tmpVar()),
-			fmt.Sprintf("uintptr(len(%s))", p.Name),
-		}
-	default:
-		s = p.Name
-	}
-	return []string{fmt.Sprintf("uintptr(%s)", s)}
-}
-
-// IsError determines if p parameter is used to return error.
-func (p *Param) IsError() bool {
-	return p.Name == "err" && p.Type == "error"
-}
-
-// HelperType returns type of parameter p used in helper function.
-func (p *Param) HelperType() string {
-	if p.Type == "string" {
-		return p.fn.StrconvType()
-	}
-	return p.Type
-}
-
-// join concatenates parameters ps into a string with sep separator.
-// Each parameter is converted into string by applying fn to it
-// before conversion.
-func join(ps []*Param, fn func(*Param) string, sep string) string {
-	if len(ps) == 0 {
-		return ""
-	}
-	a := make([]string, 0)
-	for _, p := range ps {
-		a = append(a, fn(p))
-	}
-	return strings.Join(a, sep)
-}
-
-// Rets describes function return parameters.
-type Rets struct {
-	Name         string
-	Type         string
-	ReturnsError bool
-	FailCond     string
-}
-
-// ErrorVarName returns error variable name for r.
-func (r *Rets) ErrorVarName() string {
-	if r.ReturnsError {
-		return "err"
-	}
-	if r.Type == "error" {
-		return r.Name
-	}
-	return ""
-}
-
-// ToParams converts r into slice of *Param.
-func (r *Rets) ToParams() []*Param {
-	ps := make([]*Param, 0)
-	if len(r.Name) > 0 {
-		ps = append(ps, &Param{Name: r.Name, Type: r.Type})
-	}
-	if r.ReturnsError {
-		ps = append(ps, &Param{Name: "err", Type: "error"})
-	}
-	return ps
-}
-
-// List returns source code of syscall return parameters.
-func (r *Rets) List() string {
-	s := join(r.ToParams(), func(p *Param) string { return p.Name + " " + p.Type }, ", ")
-	if len(s) > 0 {
-		s = "(" + s + ")"
-	}
-	return s
-}
-
-// PrintList returns source code of trace printing part correspondent
-// to syscall return values.
-func (r *Rets) PrintList() string {
-	return join(r.ToParams(), func(p *Param) string { return fmt.Sprintf(`"%s=", %s, `, p.Name, p.Name) }, `", ", `)
-}
-
-// SetReturnValuesCode returns source code that accepts syscall return values.
-func (r *Rets) SetReturnValuesCode() string {
-	if r.Name == "" && !r.ReturnsError {
-		return ""
-	}
-	retvar := "r0"
-	if r.Name == "" {
-		retvar = "r1"
-	}
-	errvar := "_"
-	if r.ReturnsError {
-		errvar = "e1"
-	}
-	return fmt.Sprintf("%s, _, %s := ", retvar, errvar)
-}
-
-func (r *Rets) useLongHandleErrorCode(retvar string) string {
-	const code = `if %s {
-		if e1 != 0 {
-			err = error(e1)
-		} else {
-			err = %sEINVAL
-		}
-	}`
-	cond := retvar + " == 0"
-	if r.FailCond != "" {
-		cond = strings.Replace(r.FailCond, "failretval", retvar, 1)
-	}
-	return fmt.Sprintf(code, cond, syscalldot())
-}
-
-// SetErrorCode returns source code that sets return parameters.
-func (r *Rets) SetErrorCode() string {
-	const code = `if r0 != 0 {
-		%s = %sErrno(r0)
-	}`
-	if r.Name == "" && !r.ReturnsError {
-		return ""
-	}
-	if r.Name == "" {
-		return r.useLongHandleErrorCode("r1")
-	}
-	if r.Type == "error" {
-		return fmt.Sprintf(code, r.Name, syscalldot())
-	}
-	s := ""
-	switch {
-	case r.Type[0] == '*':
-		s = fmt.Sprintf("%s = (%s)(unsafe.Pointer(r0))", r.Name, r.Type)
-	case r.Type == "bool":
-		s = fmt.Sprintf("%s = r0 != 0", r.Name)
-	default:
-		s = fmt.Sprintf("%s = %s(r0)", r.Name, r.Type)
-	}
-	if !r.ReturnsError {
-		return s
-	}
-	return s + "\n\t" + r.useLongHandleErrorCode(r.Name)
-}
-
-// Fn describes syscall function.
-type Fn struct {
-	Name        string
-	Params      []*Param
-	Rets        *Rets
-	PrintTrace  bool
-	dllname     string
-	dllfuncname string
-	src         string
-	// TODO: get rid of this field and just use parameter index instead
-	curTmpVarIdx int // insure tmp variables have uniq names
-}
-
-// extractParams parses s to extract function parameters.
-func extractParams(s string, f *Fn) ([]*Param, error) {
-	s = trim(s)
-	if s == "" {
-		return nil, nil
-	}
-	a := strings.Split(s, ",")
-	ps := make([]*Param, len(a))
-	for i := range ps {
-		s2 := trim(a[i])
-		b := strings.Split(s2, " ")
-		if len(b) != 2 {
-			b = strings.Split(s2, "\t")
-			if len(b) != 2 {
-				return nil, errors.New("Could not extract function parameter from \"" + s2 + "\"")
-			}
-		}
-		ps[i] = &Param{
-			Name:      trim(b[0]),
-			Type:      trim(b[1]),
-			fn:        f,
-			tmpVarIdx: -1,
-		}
-	}
-	return ps, nil
-}
-
-// extractSection extracts text out of string s starting after start
-// and ending just before end. found return value will indicate success,
-// and prefix, body and suffix will contain correspondent parts of string s.
-func extractSection(s string, start, end rune) (prefix, body, suffix string, found bool) {
-	s = trim(s)
-	if strings.HasPrefix(s, string(start)) {
-		// no prefix
-		body = s[1:]
-	} else {
-		a := strings.SplitN(s, string(start), 2)
-		if len(a) != 2 {
-			return "", "", s, false
-		}
-		prefix = a[0]
-		body = a[1]
-	}
-	a := strings.SplitN(body, string(end), 2)
-	if len(a) != 2 {
-		return "", "", "", false
-	}
-	return prefix, a[0], a[1], true
-}
-
-// newFn parses string s and return created function Fn.
-func newFn(s string) (*Fn, error) {
-	s = trim(s)
-	f := &Fn{
-		Rets:       &Rets{},
-		src:        s,
-		PrintTrace: *printTraceFlag,
-	}
-	// function name and args
-	prefix, body, s, found := extractSection(s, '(', ')')
-	if !found || prefix == "" {
-		return nil, errors.New("Could not extract function name and parameters from \"" + f.src + "\"")
-	}
-	f.Name = prefix
-	var err error
-	f.Params, err = extractParams(body, f)
-	if err != nil {
-		return nil, err
-	}
-	// return values
-	_, body, s, found = extractSection(s, '(', ')')
-	if found {
-		r, err := extractParams(body, f)
-		if err != nil {
-			return nil, err
-		}
-		switch len(r) {
-		case 0:
-		case 1:
-			if r[0].IsError() {
-				f.Rets.ReturnsError = true
-			} else {
-				f.Rets.Name = r[0].Name
-				f.Rets.Type = r[0].Type
-			}
-		case 2:
-			if !r[1].IsError() {
-				return nil, errors.New("Only last windows error is allowed as second return value in \"" + f.src + "\"")
-			}
-			f.Rets.ReturnsError = true
-			f.Rets.Name = r[0].Name
-			f.Rets.Type = r[0].Type
-		default:
-			return nil, errors.New("Too many return values in \"" + f.src + "\"")
-		}
-	}
-	// fail condition
-	_, body, s, found = extractSection(s, '[', ']')
-	if found {
-		f.Rets.FailCond = body
-	}
-	// dll and dll function names
-	s = trim(s)
-	if s == "" {
-		return f, nil
-	}
-	if !strings.HasPrefix(s, "=") {
-		return nil, errors.New("Could not extract dll name from \"" + f.src + "\"")
-	}
-	s = trim(s[1:])
-	a := strings.Split(s, ".")
-	switch len(a) {
-	case 1:
-		f.dllfuncname = a[0]
-	case 2:
-		f.dllname = a[0]
-		f.dllfuncname = a[1]
-	default:
-		return nil, errors.New("Could not extract dll name from \"" + f.src + "\"")
-	}
-	return f, nil
-}
-
-// DLLName returns DLL name for function f.
-func (f *Fn) DLLName() string {
-	if f.dllname == "" {
-		return "kernel32"
-	}
-	return f.dllname
-}
-
-// DLLName returns DLL function name for function f.
-func (f *Fn) DLLFuncName() string {
-	if f.dllfuncname == "" {
-		return f.Name
-	}
-	return f.dllfuncname
-}
-
-// ParamList returns source code for function f parameters.
-func (f *Fn) ParamList() string {
-	return join(f.Params, func(p *Param) string { return p.Name + " " + p.Type }, ", ")
-}
-
-// HelperParamList returns source code for helper function f parameters.
-func (f *Fn) HelperParamList() string {
-	return join(f.Params, func(p *Param) string { return p.Name + " " + p.HelperType() }, ", ")
-}
-
-// ParamPrintList returns source code of trace printing part correspondent
-// to syscall input parameters.
-func (f *Fn) ParamPrintList() string {
-	return join(f.Params, func(p *Param) string { return fmt.Sprintf(`"%s=", %s, `, p.Name, p.Name) }, `", ", `)
-}
-
-// ParamCount return number of syscall parameters for function f.
-func (f *Fn) ParamCount() int {
-	n := 0
-	for _, p := range f.Params {
-		n += len(p.SyscallArgList())
-	}
-	return n
-}
-
-// SyscallParamCount determines which version of Syscall/Syscall6/Syscall9/...
-// to use. It returns parameter count for correspondent SyscallX function.
-func (f *Fn) SyscallParamCount() int {
-	n := f.ParamCount()
-	switch {
-	case n <= 3:
-		return 3
-	case n <= 6:
-		return 6
-	case n <= 9:
-		return 9
-	case n <= 12:
-		return 12
-	case n <= 15:
-		return 15
-	default:
-		panic("too many arguments to system call")
-	}
-}
-
-// Syscall determines which SyscallX function to use for function f.
-func (f *Fn) Syscall() string {
-	c := f.SyscallParamCount()
-	if c == 3 {
-		return syscalldot() + "Syscall"
-	}
-	return syscalldot() + "Syscall" + strconv.Itoa(c)
-}
-
-// SyscallParamList returns source code for SyscallX parameters for function f.
-func (f *Fn) SyscallParamList() string {
-	a := make([]string, 0)
-	for _, p := range f.Params {
-		a = append(a, p.SyscallArgList()...)
-	}
-	for len(a) < f.SyscallParamCount() {
-		a = append(a, "0")
-	}
-	return strings.Join(a, ", ")
-}
-
-// HelperCallParamList returns source code of call into function f helper.
-func (f *Fn) HelperCallParamList() string {
-	a := make([]string, 0, len(f.Params))
-	for _, p := range f.Params {
-		s := p.Name
-		if p.Type == "string" {
-			s = p.tmpVar()
-		}
-		a = append(a, s)
-	}
-	return strings.Join(a, ", ")
-}
-
-// IsUTF16 is true, if f is W (utf16) function. It is false
-// for all A (ascii) functions.
-func (f *Fn) IsUTF16() bool {
-	s := f.DLLFuncName()
-	return s[len(s)-1] == 'W'
-}
-
-// StrconvFunc returns name of Go string to OS string function for f.
-func (f *Fn) StrconvFunc() string {
-	if f.IsUTF16() {
-		return syscalldot() + "UTF16PtrFromString"
-	}
-	return syscalldot() + "BytePtrFromString"
-}
-
-// StrconvType returns Go type name used for OS string for f.
-func (f *Fn) StrconvType() string {
-	if f.IsUTF16() {
-		return "*uint16"
-	}
-	return "*byte"
-}
-
-// HasStringParam is true, if f has at least one string parameter.
-// Otherwise it is false.
-func (f *Fn) HasStringParam() bool {
-	for _, p := range f.Params {
-		if p.Type == "string" {
-			return true
-		}
-	}
-	return false
-}
-
-// HelperName returns name of function f helper.
-func (f *Fn) HelperName() string {
-	if !f.HasStringParam() {
-		return f.Name
-	}
-	return "_" + f.Name
-}
-
-// Source files and functions.
-type Source struct {
-	Funcs           []*Fn
-	Files           []string
-	StdLibImports   []string
-	ExternalImports []string
-}
-
-func (src *Source) Import(pkg string) {
-	src.StdLibImports = append(src.StdLibImports, pkg)
-	sort.Strings(src.StdLibImports)
-}
-
-func (src *Source) ExternalImport(pkg string) {
-	src.ExternalImports = append(src.ExternalImports, pkg)
-	sort.Strings(src.ExternalImports)
-}
-
-// ParseFiles parses files listed in fs and extracts all syscall
-// functions listed in  sys comments. It returns source files
-// and functions collection *Source if successful.
-func ParseFiles(fs []string) (*Source, error) {
-	src := &Source{
-		Funcs: make([]*Fn, 0),
-		Files: make([]string, 0),
-		StdLibImports: []string{
-			"unsafe",
-		},
-		ExternalImports: make([]string, 0),
-	}
-	for _, file := range fs {
-		if err := src.ParseFile(file); err != nil {
-			return nil, err
-		}
-	}
-	return src, nil
-}
-
-// DLLs return dll names for a source set src.
-func (src *Source) DLLs() []string {
-	uniq := make(map[string]bool)
-	r := make([]string, 0)
-	for _, f := range src.Funcs {
-		name := f.DLLName()
-		if _, found := uniq[name]; !found {
-			uniq[name] = true
-			r = append(r, name)
-		}
-	}
-	return r
-}
-
-// ParseFile adds additional file path to a source set src.
-func (src *Source) ParseFile(path string) error {
-	file, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	s := bufio.NewScanner(file)
-	for s.Scan() {
-		t := trim(s.Text())
-		if len(t) < 7 {
-			continue
-		}
-		if !strings.HasPrefix(t, "//sys") {
-			continue
-		}
-		t = t[5:]
-		if !(t[0] == ' ' || t[0] == '\t') {
-			continue
-		}
-		f, err := newFn(t[1:])
-		if err != nil {
-			return err
-		}
-		src.Funcs = append(src.Funcs, f)
-	}
-	if err := s.Err(); err != nil {
-		return err
-	}
-	src.Files = append(src.Files, path)
-
-	// get package name
-	fset := token.NewFileSet()
-	_, err = file.Seek(0, 0)
-	if err != nil {
-		return err
-	}
-	pkg, err := parser.ParseFile(fset, "", file, parser.PackageClauseOnly)
-	if err != nil {
-		return err
-	}
-	packageName = pkg.Name.Name
-
-	return nil
-}
-
-// IsStdRepo returns true if src is part of standard library.
-func (src *Source) IsStdRepo() (bool, error) {
-	if len(src.Files) == 0 {
-		return false, errors.New("no input files provided")
-	}
-	abspath, err := filepath.Abs(src.Files[0])
-	if err != nil {
-		return false, err
-	}
-	goroot := runtime.GOROOT()
-	if runtime.GOOS == "windows" {
-		abspath = strings.ToLower(abspath)
-		goroot = strings.ToLower(goroot)
-	}
-	return strings.HasPrefix(abspath, goroot), nil
-}
-
-// Generate output source file from a source set src.
-func (src *Source) Generate(w io.Writer) error {
-	const (
-		pkgStd         = iota // any package in std library
-		pkgXSysWindows        // x/sys/windows package
-		pkgOther
-	)
-	isStdRepo, err := src.IsStdRepo()
-	if err != nil {
-		return err
-	}
-	var pkgtype int
-	switch {
-	case isStdRepo:
-		pkgtype = pkgStd
-	case packageName == "windows":
-		// TODO: this needs better logic than just using package name
-		pkgtype = pkgXSysWindows
-	default:
-		pkgtype = pkgOther
-	}
-	if *systemDLL {
-		switch pkgtype {
-		case pkgStd:
-			src.Import("internal/syscall/windows/sysdll")
-		case pkgXSysWindows:
-		default:
-			src.ExternalImport("golang.org/x/sys/windows")
-		}
-	}
-	if packageName != "syscall" {
-		src.Import("syscall")
-	}
-	funcMap := template.FuncMap{
-		"packagename": packagename,
-		"syscalldot":  syscalldot,
-		"newlazydll": func(dll string) string {
-			arg := "\"" + dll + ".dll\""
-			if !*systemDLL {
-				return syscalldot() + "NewLazyDLL(" + arg + ")"
-			}
-			switch pkgtype {
-			case pkgStd:
-				return syscalldot() + "NewLazyDLL(sysdll.Add(" + arg + "))"
-			case pkgXSysWindows:
-				return "NewLazySystemDLL(" + arg + ")"
-			default:
-				return "windows.NewLazySystemDLL(" + arg + ")"
-			}
-		},
-	}
-	t := template.Must(template.New("main").Funcs(funcMap).Parse(srcTemplate))
-	err = t.Execute(w, src)
-	if err != nil {
-		return errors.New("Failed to execute template: " + err.Error())
-	}
-	return nil
-}
-
-func usage() {
-	fmt.Fprintf(os.Stderr, "usage: mksyscall_windows [flags] [path ...]\n")
-	flag.PrintDefaults()
-	os.Exit(1)
-}
-
-func main() {
-	flag.Usage = usage
-	flag.Parse()
-	if len(flag.Args()) <= 0 {
-		fmt.Fprintf(os.Stderr, "no files to parse provided\n")
-		usage()
-	}
-
-	src, err := ParseFiles(flag.Args())
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	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)
-	}
-}
-
-// TODO: use println instead to print in the following template
-const srcTemplate = `
-
-{{define "main"}}// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
-
-package {{packagename}}
-
-import (
-{{range .StdLibImports}}"{{.}}"
-{{end}}
-
-{{range .ExternalImports}}"{{.}}"
-{{end}}
-)
-
-var _ unsafe.Pointer
-
-var (
-{{template "dlls" .}}
-{{template "funcnames" .}})
-{{range .Funcs}}{{if .HasStringParam}}{{template "helperbody" .}}{{end}}{{template "funcbody" .}}{{end}}
-{{end}}
-
-{{/* help functions */}}
-
-{{define "dlls"}}{{range .DLLs}}	mod{{.}} = {{newlazydll .}}
-{{end}}{{end}}
-
-{{define "funcnames"}}{{range .Funcs}}	proc{{.DLLFuncName}} = mod{{.DLLName}}.NewProc("{{.DLLFuncName}}")
-{{end}}{{end}}
-
-{{define "helperbody"}}
-func {{.Name}}({{.ParamList}}) {{template "results" .}}{
-{{template "helpertmpvars" .}}	return {{.HelperName}}({{.HelperCallParamList}})
-}
-{{end}}
-
-{{define "funcbody"}}
-func {{.HelperName}}({{.HelperParamList}}) {{template "results" .}}{
-{{template "tmpvars" .}}	{{template "syscall" .}}
-{{template "seterror" .}}{{template "printtrace" .}}	return
-}
-{{end}}
-
-{{define "helpertmpvars"}}{{range .Params}}{{if .TmpVarHelperCode}}	{{.TmpVarHelperCode}}
-{{end}}{{end}}{{end}}
-
-{{define "tmpvars"}}{{range .Params}}{{if .TmpVarCode}}	{{.TmpVarCode}}
-{{end}}{{end}}{{end}}
-
-{{define "results"}}{{if .Rets.List}}{{.Rets.List}} {{end}}{{end}}
-
-{{define "syscall"}}{{.Rets.SetReturnValuesCode}}{{.Syscall}}(proc{{.DLLFuncName}}.Addr(), {{.ParamCount}}, {{.SyscallParamList}}){{end}}
-
-{{define "seterror"}}{{if .Rets.SetErrorCode}}	{{.Rets.SetErrorCode}}
-{{end}}{{end}}
-
-{{define "printtrace"}}{{if .PrintTrace}}	print("SYSCALL: {{.Name}}(", {{.ParamPrintList}}") (", {{.Rets.PrintList}}")\n")
-{{end}}{{end}}
-
-`

serial.go

@@ -6,7 +6,7 @@
 
 package serial // import "go.bug.st/serial.v1"
 
-//go:generate go run extras/mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go
 
 // Port is the interface for a serial Port
 type Port interface {

zsyscall_windows.go

@@ -11,6 +11,31 @@ import (
 
 var _ unsafe.Pointer
 
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
 var (
 	modadvapi32 = windows.NewLazySystemDLL("advapi32.dll")
 	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
@@ -38,7 +63,7 @@ func getCommState(handle syscall.Handle, dcb *dcb) (err error) {
 	r1, _, e1 := syscall.Syscall(procGetCommState.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(dcb)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -50,7 +75,7 @@ func setCommState(handle syscall.Handle, dcb *dcb) (err error) {
 	r1, _, e1 := syscall.Syscall(procSetCommState.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(dcb)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -62,7 +87,7 @@ func setCommTimeouts(handle syscall.Handle, timeouts *commTimeouts) (err error)
 	r1, _, e1 := syscall.Syscall(procSetCommTimeouts.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(timeouts)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -99,7 +124,7 @@ func createEvent(eventAttributes *uint32, manualReset bool, initialState bool, n
 	handle = syscall.Handle(r0)
 	if handle == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -111,7 +136,7 @@ func resetEvent(handle syscall.Handle) (err error) {
 	r1, _, e1 := syscall.Syscall(procResetEvent.Addr(), 1, uintptr(handle), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -129,7 +154,7 @@ func getOverlappedResult(handle syscall.Handle, overlapEvent *syscall.Overlapped
 	r1, _, e1 := syscall.Syscall6(procGetOverlappedResult.Addr(), 4, uintptr(handle), uintptr(unsafe.Pointer(overlapEvent)), uintptr(unsafe.Pointer(n)), uintptr(_p0), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}