src/syscall/exec_windows.go - go - Git at Google

 // Copyright 2009 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.

 // Fork, exec, wait, etc.

 package syscall

 import (
 	"sync"
 	"unicode/utf16"
 	"unsafe"
 )

 var ForkLock sync.RWMutex

 // EscapeArg rewrites command line argument s as prescribed
 // in http://msdn.microsoft.com/en-us/library/ms880421.
 // This function returns "" (2 double quotes) if s is empty.
 // Alternatively, these transformations are done:
 // - every back slash (\) is doubled, but only if immediately
 //   followed by double quote (");
 // - every double quote (") is escaped by back slash (\);
 // - finally, s is wrapped with double quotes (arg -> "arg"),
 //   but only if there is space or tab inside s.
 func EscapeArg(s string) string {
 	if len(s) == 0 {
 		return "\"\""
 	}
 	n := len(s)
 	hasSpace := false
 	for i := 0; i < len(s); i++ {
 		switch s[i] {
 		case '"', '\\':
 			n++
 		case ' ', '\t':
 			hasSpace = true
 		}
 	}
 	if hasSpace {
 		n += 2
 	}
 	if n == len(s) {
 		return s
 	}

 	qs := make([]byte, n)
 	j := 0
 	if hasSpace {
 		qs[j] = '"'
 		j++
 	}
 	slashes := 0
 	for i := 0; i < len(s); i++ {
 		switch s[i] {
 		default:
 			slashes = 0
 			qs[j] = s[i]
 		case '\\':
 			slashes++
 			qs[j] = s[i]
 		case '"':
 			for ; slashes > 0; slashes-- {
 				qs[j] = '\\'
 				j++
 			}
 			qs[j] = '\\'
 			j++
 			qs[j] = s[i]
 		}
 		j++
 	}
 	if hasSpace {
 		for ; slashes > 0; slashes-- {
 			qs[j] = '\\'
 			j++
 		}
 		qs[j] = '"'
 		j++
 	}
 	return string(qs[:j])
 }

 // makeCmdLine builds a command line out of args by escaping "special"
 // characters and joining the arguments with spaces.
 func makeCmdLine(args []string) string {
 	var s string
 	for _, v := range args {
 		if s != "" {
 			s += " "
 		}
 		s += EscapeArg(v)
 	}
 	return s
 }

 // createEnvBlock converts an array of environment strings into
 // the representation required by CreateProcess: a sequence of NUL
 // terminated strings followed by a nil.
 // Last bytes are two UCS-2 NULs, or four NUL bytes.
 func createEnvBlock(envv []string) *uint16 {
 	if len(envv) == 0 {
 		return &utf16.Encode([]rune("\x00\x00"))[0]
 	}
 	length := 0
 	for _, s := range envv {
 		length += len(s) + 1
 	}
 	length += 1

 	b := make([]byte, length)
 	i := 0
 	for _, s := range envv {
 		l := len(s)
 		copy(b[i:i+l], []byte(s))
 		copy(b[i+l:i+l+1], []byte{0})
 		i = i + l + 1
 	}
 	copy(b[i:i+1], []byte{0})

 	return &utf16.Encode([]rune(string(b)))[0]
 }

 func CloseOnExec(fd Handle) {
 	SetHandleInformation(Handle(fd), HANDLE_FLAG_INHERIT, 0)
 }

 func SetNonblock(fd Handle, nonblocking bool) (err error) {
 	return nil
 }

 // FullPath retrieves the full path of the specified file.
 func FullPath(name string) (path string, err error) {
 	p, err := UTF16PtrFromString(name)
 	if err != nil {
 		return "", err
 	}
 	n := uint32(100)
 	for {
 		buf := make([]uint16, n)
 		n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
 		if err != nil {
 			return "", err
 		}
 		if n <= uint32(len(buf)) {
 			return UTF16ToString(buf[:n]), nil
 		}
 	}
 }

 func isSlash(c uint8) bool {
 	return c == '\\' || c == '/'
 }

 func normalizeDir(dir string) (name string, err error) {
 	ndir, err := FullPath(dir)
 	if err != nil {
 		return "", err
 	}
 	if len(ndir) > 2 && isSlash(ndir[0]) && isSlash(ndir[1]) {
 		// dir cannot have \\server\share\path form
 		return "", EINVAL
 	}
 	return ndir, nil
 }

 func volToUpper(ch int) int {
 	if 'a' <= ch && ch <= 'z' {
 		ch += 'A' - 'a'
 	}
 	return ch
 }

 func joinExeDirAndFName(dir, p string) (name string, err error) {
 	if len(p) == 0 {
 		return "", EINVAL
 	}
 	if len(p) > 2 && isSlash(p[0]) && isSlash(p[1]) {
 		// \\server\share\path form
 		return p, nil
 	}
 	if len(p) > 1 && p[1] == ':' {
 		// has drive letter
 		if len(p) == 2 {
 			return "", EINVAL
 		}
 		if isSlash(p[2]) {
 			return p, nil
 		} else {
 			d, err := normalizeDir(dir)
 			if err != nil {
 				return "", err
 			}
 			if volToUpper(int(p[0])) == volToUpper(int(d[0])) {
 				return FullPath(d + "\\" + p[2:])
 			} else {
 				return FullPath(p)
 			}
 		}
 	} else {
 		// no drive letter
 		d, err := normalizeDir(dir)
 		if err != nil {
 			return "", err
 		}
 		if isSlash(p[0]) {
 			return FullPath(d[:2] + p)
 		} else {
 			return FullPath(d + "\\" + p)
 		}
 	}
 	// we shouldn't be here
 	return "", EINVAL
 }

 type ProcAttr struct {
 	Dir   string
 	Env   []string
 	Files []uintptr
 	Sys   *SysProcAttr
 }

 type SysProcAttr struct {
 	HideWindow    bool
 	CmdLine       string // used if non-empty, else the windows command line is built by escaping the arguments passed to StartProcess
 	CreationFlags uint32
 }

 var zeroProcAttr ProcAttr
 var zeroSysProcAttr SysProcAttr

 func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error) {
 	if len(argv0) == 0 {
 		return 0, 0, EWINDOWS
 	}
 	if attr == nil {
 		attr = &zeroProcAttr
 	}
 	sys := attr.Sys
 	if sys == nil {
 		sys = &zeroSysProcAttr
 	}

 	if len(attr.Files) > 3 {
 		return 0, 0, EWINDOWS
 	}
 	if len(attr.Files) < 3 {
 		return 0, 0, EINVAL
 	}

 	if len(attr.Dir) != 0 {
 		// StartProcess assumes that argv0 is relative to attr.Dir,
 		// because it implies Chdir(attr.Dir) before executing argv0.
 		// Windows CreateProcess assumes the opposite: it looks for
 		// argv0 relative to the current directory, and, only once the new
 		// process is started, it does Chdir(attr.Dir). We are adjusting
 		// for that difference here by making argv0 absolute.
 		var err error
 		argv0, err = joinExeDirAndFName(attr.Dir, argv0)
 		if err != nil {
 			return 0, 0, err
 		}
 	}
 	argv0p, err := UTF16PtrFromString(argv0)
 	if err != nil {
 		return 0, 0, err
 	}

 	var cmdline string
 	// Windows CreateProcess takes the command line as a single string:
 	// use attr.CmdLine if set, else build the command line by escaping
 	// and joining each argument with spaces
 	if sys.CmdLine != "" {
 		cmdline = sys.CmdLine
 	} else {
 		cmdline = makeCmdLine(argv)
 	}

 	var argvp *uint16
 	if len(cmdline) != 0 {
 		argvp, err = UTF16PtrFromString(cmdline)
 		if err != nil {
 			return 0, 0, err
 		}
 	}

 	var dirp *uint16
 	if len(attr.Dir) != 0 {
 		dirp, err = UTF16PtrFromString(attr.Dir)
 		if err != nil {
 			return 0, 0, err
 		}
 	}

 	// Acquire the fork lock so that no other threads
 	// create new fds that are not yet close-on-exec
 	// before we fork.
 	ForkLock.Lock()
 	defer ForkLock.Unlock()

 	p, _ := GetCurrentProcess()
 	fd := make([]Handle, len(attr.Files))
 	for i := range attr.Files {
 		if attr.Files[i] > 0 {
 			err := DuplicateHandle(p, Handle(attr.Files[i]), p, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
 			if err != nil {
 				return 0, 0, err
 			}
 			defer CloseHandle(Handle(fd[i]))
 		}
 	}
 	si := new(StartupInfo)
 	si.Cb = uint32(unsafe.Sizeof(*si))
 	si.Flags = STARTF_USESTDHANDLES
 	if sys.HideWindow {
 		si.Flags |= STARTF_USESHOWWINDOW
 		si.ShowWindow = SW_HIDE
 	}
 	si.StdInput = fd[0]
 	si.StdOutput = fd[1]
 	si.StdErr = fd[2]

 	pi := new(ProcessInformation)

 	flags := sys.CreationFlags | CREATE_UNICODE_ENVIRONMENT
 	err = CreateProcess(argv0p, argvp, nil, nil, true, flags, createEnvBlock(attr.Env), dirp, si, pi)
 	if err != nil {
 		return 0, 0, err
 	}
 	defer CloseHandle(Handle(pi.Thread))

 	return int(pi.ProcessId), uintptr(pi.Process), nil
 }

 func Exec(argv0 string, argv []string, envv []string) (err error) {
 	return EWINDOWS
 }
	// Copyright 2009 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.

	// Fork, exec, wait, etc.

	package syscall

	import (
	"sync"
	"unicode/utf16"
	"unsafe"
	)

	var ForkLock sync.RWMutex

	// EscapeArg rewrites command line argument s as prescribed
	// in http://msdn.microsoft.com/en-us/library/ms880421.
	// This function returns "" (2 double quotes) if s is empty.
	// Alternatively, these transformations are done:
	// - every back slash (\) is doubled, but only if immediately
	// followed by double quote (");
	// - every double quote (") is escaped by back slash (\);
	// - finally, s is wrapped with double quotes (arg -> "arg"),
	// but only if there is space or tab inside s.
	func EscapeArg(s string) string {
	if len(s) == 0 {
	return "\"\""
	}
	n := len(s)
	hasSpace := false
	for i := 0; i < len(s); i++ {
	switch s[i] {
	case '"', '\\':
	n++
	case ' ', '\t':
	hasSpace = true
	}
	}
	if hasSpace {
	n += 2
	}
	if n == len(s) {
	return s
	}

	qs := make([]byte, n)
	j := 0
	if hasSpace {
	qs[j] = '"'
	j++
	}
	slashes := 0
	for i := 0; i < len(s); i++ {
	switch s[i] {
	default:
	slashes = 0
	qs[j] = s[i]
	case '\\':
	slashes++
	qs[j] = s[i]
	case '"':
	for ; slashes > 0; slashes-- {
	qs[j] = '\\'
	j++
	}
	qs[j] = '\\'
	j++
	qs[j] = s[i]
	}
	j++
	}
	if hasSpace {
	for ; slashes > 0; slashes-- {
	qs[j] = '\\'
	j++
	}
	qs[j] = '"'
	j++
	}
	return string(qs[:j])
	}

	// makeCmdLine builds a command line out of args by escaping "special"
	// characters and joining the arguments with spaces.
	func makeCmdLine(args []string) string {
	var s string
	for _, v := range args {
	if s != "" {
	s += " "
	}
	s += EscapeArg(v)
	}
	return s
	}

	// createEnvBlock converts an array of environment strings into
	// the representation required by CreateProcess: a sequence of NUL
	// terminated strings followed by a nil.
	// Last bytes are two UCS-2 NULs, or four NUL bytes.
	func createEnvBlock(envv []string) *uint16 {
	if len(envv) == 0 {
	return &utf16.Encode([]rune("\x00\x00"))[0]
	}
	length := 0
	for _, s := range envv {
	length += len(s) + 1
	}
	length += 1

	b := make([]byte, length)
	i := 0
	for _, s := range envv {
	l := len(s)
	copy(b[i:i+l], []byte(s))
	copy(b[i+l:i+l+1], []byte{0})
	i = i + l + 1
	}
	copy(b[i:i+1], []byte{0})

	return &utf16.Encode([]rune(string(b)))[0]
	}

	func CloseOnExec(fd Handle) {
	SetHandleInformation(Handle(fd), HANDLE_FLAG_INHERIT, 0)
	}

	func SetNonblock(fd Handle, nonblocking bool) (err error) {
	return nil
	}

	// FullPath retrieves the full path of the specified file.
	func FullPath(name string) (path string, err error) {
	p, err := UTF16PtrFromString(name)
	if err != nil {
	return "", err
	}
	n := uint32(100)
	for {
	buf := make([]uint16, n)
	n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
	if err != nil {
	return "", err
	}
	if n <= uint32(len(buf)) {
	return UTF16ToString(buf[:n]), nil
	}
	}
	}

	func isSlash(c uint8) bool {
	return c == '\\' \|\| c == '/'
	}

	func normalizeDir(dir string) (name string, err error) {
	ndir, err := FullPath(dir)
	if err != nil {
	return "", err
	}
	if len(ndir) > 2 && isSlash(ndir[0]) && isSlash(ndir[1]) {
	// dir cannot have \\server\share\path form
	return "", EINVAL
	}
	return ndir, nil
	}

	func volToUpper(ch int) int {
	if 'a' <= ch && ch <= 'z' {
	ch += 'A' - 'a'
	}
	return ch
	}

	func joinExeDirAndFName(dir, p string) (name string, err error) {
	if len(p) == 0 {
	return "", EINVAL
	}
	if len(p) > 2 && isSlash(p[0]) && isSlash(p[1]) {
	// \\server\share\path form
	return p, nil
	}
	if len(p) > 1 && p[1] == ':' {
	// has drive letter
	if len(p) == 2 {
	return "", EINVAL
	}
	if isSlash(p[2]) {
	return p, nil
	} else {
	d, err := normalizeDir(dir)
	if err != nil {
	return "", err
	}
	if volToUpper(int(p[0])) == volToUpper(int(d[0])) {
	return FullPath(d + "\\" + p[2:])
	} else {
	return FullPath(p)
	}
	}
	} else {
	// no drive letter
	d, err := normalizeDir(dir)
	if err != nil {
	return "", err
	}
	if isSlash(p[0]) {
	return FullPath(d[:2] + p)
	} else {
	return FullPath(d + "\\" + p)
	}
	}
	// we shouldn't be here
	return "", EINVAL
	}

	type ProcAttr struct {
	Dir string
	Env []string
	Files []uintptr
	Sys *SysProcAttr
	}

	type SysProcAttr struct {
	HideWindow bool
	CmdLine string // used if non-empty, else the windows command line is built by escaping the arguments passed to StartProcess
	CreationFlags uint32
	}

	var zeroProcAttr ProcAttr
	var zeroSysProcAttr SysProcAttr

	func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error) {
	if len(argv0) == 0 {
	return 0, 0, EWINDOWS
	}
	if attr == nil {
	attr = &zeroProcAttr
	}
	sys := attr.Sys
	if sys == nil {
	sys = &zeroSysProcAttr
	}

	if len(attr.Files) > 3 {
	return 0, 0, EWINDOWS
	}
	if len(attr.Files) < 3 {
	return 0, 0, EINVAL
	}

	if len(attr.Dir) != 0 {
	// StartProcess assumes that argv0 is relative to attr.Dir,
	// because it implies Chdir(attr.Dir) before executing argv0.
	// Windows CreateProcess assumes the opposite: it looks for
	// argv0 relative to the current directory, and, only once the new
	// process is started, it does Chdir(attr.Dir). We are adjusting
	// for that difference here by making argv0 absolute.
	var err error
	argv0, err = joinExeDirAndFName(attr.Dir, argv0)
	if err != nil {
	return 0, 0, err
	}
	}
	argv0p, err := UTF16PtrFromString(argv0)
	if err != nil {
	return 0, 0, err
	}

	var cmdline string
	// Windows CreateProcess takes the command line as a single string:
	// use attr.CmdLine if set, else build the command line by escaping
	// and joining each argument with spaces
	if sys.CmdLine != "" {
	cmdline = sys.CmdLine
	} else {
	cmdline = makeCmdLine(argv)
	}

	var argvp *uint16
	if len(cmdline) != 0 {
	argvp, err = UTF16PtrFromString(cmdline)
	if err != nil {
	return 0, 0, err
	}
	}

	var dirp *uint16
	if len(attr.Dir) != 0 {
	dirp, err = UTF16PtrFromString(attr.Dir)
	if err != nil {
	return 0, 0, err
	}
	}

	// Acquire the fork lock so that no other threads
	// create new fds that are not yet close-on-exec
	// before we fork.
	ForkLock.Lock()
	defer ForkLock.Unlock()

	p, _ := GetCurrentProcess()
	fd := make([]Handle, len(attr.Files))
	for i := range attr.Files {
	if attr.Files[i] > 0 {
	err := DuplicateHandle(p, Handle(attr.Files[i]), p, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
	if err != nil {
	return 0, 0, err
	}
	defer CloseHandle(Handle(fd[i]))
	}
	}
	si := new(StartupInfo)
	si.Cb = uint32(unsafe.Sizeof(*si))
	si.Flags = STARTF_USESTDHANDLES
	if sys.HideWindow {
	si.Flags \|= STARTF_USESHOWWINDOW
	si.ShowWindow = SW_HIDE
	}
	si.StdInput = fd[0]
	si.StdOutput = fd[1]
	si.StdErr = fd[2]

	pi := new(ProcessInformation)

	flags := sys.CreationFlags \| CREATE_UNICODE_ENVIRONMENT
	err = CreateProcess(argv0p, argvp, nil, nil, true, flags, createEnvBlock(attr.Env), dirp, si, pi)
	if err != nil {
	return 0, 0, err
	}
	defer CloseHandle(Handle(pi.Thread))

	return int(pi.ProcessId), uintptr(pi.Process), nil
	}

	func Exec(argv0 string, argv []string, envv []string) (err error) {
	return EWINDOWS
	}