libgo/go/syscall/exec_windows.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Fork, exec, wait, etc.
   6
   7 package syscall
   8
   9 import (
  10         "sync"
  11         "unicode/utf16"
  12         "unsafe"
  13 )
  14
  15 var ForkLock sync.RWMutex
  16
  17 // EscapeArg rewrites command line argument s as prescribed
  18 // in http://msdn.microsoft.com/en-us/library/ms880421.
  19 // This function returns "" (2 double quotes) if s is empty.
  20 // Alternatively, these transformations are done:
  21 // - every back slash (\) is doubled, but only if immediately
  22 //   followed by double quote (");
  23 // - every double quote (") is escaped by back slash (\);
  24 // - finally, s is wrapped with double quotes (arg -> "arg"),
  25 //   but only if there is space or tab inside s.
  26 func EscapeArg(s string) string {
  27         if len(s) == 0 {
  28                 return "\"\""
  29         }
  30         n := len(s)
  31         hasSpace := false
  32         for i := 0; i < len(s); i++ {
  33                 switch s[i] {
  34                 case '"', '\\':
  35                         n++
  36                 case ' ', '\t':
  37                         hasSpace = true
  38                 }
  39         }
  40         if hasSpace {
  41                 n += 2
  42         }
  43         if n == len(s) {
  44                 return s
  45         }
  46
  47         qs := make([]byte, n)
  48         j := 0
  49         if hasSpace {
  50                 qs[j] = '"'
  51                 j++
  52         }
  53         slashes := 0
  54         for i := 0; i < len(s); i++ {
  55                 switch s[i] {
  56                 default:
  57                         slashes = 0
  58                         qs[j] = s[i]
  59                 case '\\':
  60                         slashes++
  61                         qs[j] = s[i]
  62                 case '"':
  63                         for ; slashes > 0; slashes-- {
  64                                 qs[j] = '\\'
  65                                 j++
  66                         }
  67                         qs[j] = '\\'
  68                         j++
  69                         qs[j] = s[i]
  70                 }
  71                 j++
  72         }
  73         if hasSpace {
  74                 for ; slashes > 0; slashes-- {
  75                         qs[j] = '\\'
  76                         j++
  77                 }
  78                 qs[j] = '"'
  79                 j++
  80         }
  81         return string(qs[:j])
  82 }
  83
  84 // makeCmdLine builds a command line out of args by escaping "special"
  85 // characters and joining the arguments with spaces.
  86 func makeCmdLine(args []string) string {
  87         var s string
  88         for _, v := range args {
  89                 if s != "" {
  90                         s += " "
  91                 }
  92                 s += EscapeArg(v)
  93         }
  94         return s
  95 }
  96
  97 // createEnvBlock converts an array of environment strings into
  98 // the representation required by CreateProcess: a sequence of NUL
  99 // terminated strings followed by a nil.
 100 // Last bytes are two UCS-2 NULs, or four NUL bytes.
 101 func createEnvBlock(envv []string) *uint16 {
 102         if len(envv) == 0 {
 103                 return &utf16.Encode([]rune("\x00\x00"))[0]
 104         }
 105         length := 0
 106         for _, s := range envv {
 107                 length += len(s) + 1
 108         }
 109         length += 1
 110
 111         b := make([]byte, length)
 112         i := 0
 113         for _, s := range envv {
 114                 l := len(s)
 115                 copy(b[i:i+l], []byte(s))
 116                 copy(b[i+l:i+l+1], []byte{0})
 117                 i = i + l + 1
 118         }
 119         copy(b[i:i+1], []byte{0})
 120
 121         return &utf16.Encode([]rune(string(b)))[0]
 122 }
 123
 124 func CloseOnExec(fd Handle) {
 125         SetHandleInformation(Handle(fd), HANDLE_FLAG_INHERIT, 0)
 126 }
 127
 128 func SetNonblock(fd Handle, nonblocking bool) (err error) {
 129         return nil
 130 }
 131
 132 // getFullPath retrieves the full path of the specified file.
 133 // Just a wrapper for Windows GetFullPathName api.
 134 func getFullPath(name string) (path string, err error) {
 135         p, err := UTF16PtrFromString(name)
 136         if err != nil {
 137                 return "", err
 138         }
 139         buf := make([]uint16, 100)
 140         n, err := GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
 141         if err != nil {
 142                 return "", err
 143         }
 144         if n > uint32(len(buf)) {
 145                 // Windows is asking for bigger buffer.
 146                 buf = make([]uint16, n)
 147                 n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
 148                 if err != nil {
 149                         return "", err
 150                 }
 151                 if n > uint32(len(buf)) {
 152                         return "", EINVAL
 153                 }
 154         }
 155         return UTF16ToString(buf[:n]), nil
 156 }
 157
 158 func isSlash(c uint8) bool {
 159         return c == '\\' || c == '/'
 160 }
 161
 162 func normalizeDir(dir string) (name string, err error) {
 163         ndir, err := getFullPath(dir)
 164         if err != nil {
 165                 return "", err
 166         }
 167         if len(ndir) > 2 && isSlash(ndir[0]) && isSlash(ndir[1]) {
 168                 // dir cannot have \\server\share\path form
 169                 return "", EINVAL
 170         }
 171         return ndir, nil
 172 }
 173
 174 func volToUpper(ch int) int {
 175         if 'a' <= ch && ch <= 'z' {
 176                 ch += 'A' - 'a'
 177         }
 178         return ch
 179 }
 180
 181 func joinExeDirAndFName(dir, p string) (name string, err error) {
 182         if len(p) == 0 {
 183                 return "", EINVAL
 184         }
 185         if len(p) > 2 && isSlash(p[0]) && isSlash(p[1]) {
 186                 // \\server\share\path form
 187                 return p, nil
 188         }
 189         if len(p) > 1 && p[1] == ':' {
 190                 // has drive letter
 191                 if len(p) == 2 {
 192                         return "", EINVAL
 193                 }
 194                 if isSlash(p[2]) {
 195                         return p, nil
 196                 } else {
 197                         d, err := normalizeDir(dir)
 198                         if err != nil {
 199                                 return "", err
 200                         }
 201                         if volToUpper(int(p[0])) == volToUpper(int(d[0])) {
 202                                 return getFullPath(d + "\\" + p[2:])
 203                         } else {
 204                                 return getFullPath(p)
 205                         }
 206                 }
 207         } else {
 208                 // no drive letter
 209                 d, err := normalizeDir(dir)
 210                 if err != nil {
 211                         return "", err
 212                 }
 213                 if isSlash(p[0]) {
 214                         return getFullPath(d[:2] + p)
 215                 } else {
 216                         return getFullPath(d + "\\" + p)
 217                 }
 218         }
 219         // we shouldn't be here
 220         return "", EINVAL
 221 }
 222
 223 type ProcAttr struct {
 224         Dir   string
 225         Env   []string
 226         Files []uintptr
 227         Sys   *SysProcAttr
 228 }
 229
 230 type SysProcAttr struct {
 231         HideWindow    bool
 232         CmdLine       string // used if non-empty, else the windows command line is built by escaping the arguments passed to StartProcess
 233         CreationFlags uint32
 234 }
 235
 236 var zeroProcAttr ProcAttr
 237 var zeroSysProcAttr SysProcAttr
 238
 239 func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error) {
 240         if len(argv0) == 0 {
 241                 return 0, 0, EWINDOWS
 242         }
 243         if attr == nil {
 244                 attr = &zeroProcAttr
 245         }
 246         sys := attr.Sys
 247         if sys == nil {
 248                 sys = &zeroSysProcAttr
 249         }
 250
 251         if len(attr.Files) > 3 {
 252                 return 0, 0, EWINDOWS
 253         }
 254
 255         if len(attr.Dir) != 0 {
 256                 // StartProcess assumes that argv0 is relative to attr.Dir,
 257                 // because it implies Chdir(attr.Dir) before executing argv0.
 258                 // Windows CreateProcess assumes the opposite: it looks for
 259                 // argv0 relative to the current directory, and, only once the new
 260                 // process is started, it does Chdir(attr.Dir). We are adjusting
 261                 // for that difference here by making argv0 absolute.
 262                 var err error
 263                 argv0, err = joinExeDirAndFName(attr.Dir, argv0)
 264                 if err != nil {
 265                         return 0, 0, err
 266                 }
 267         }
 268         argv0p, err := UTF16PtrFromString(argv0)
 269         if err != nil {
 270                 return 0, 0, err
 271         }
 272
 273         var cmdline string
 274         // Windows CreateProcess takes the command line as a single string:
 275         // use attr.CmdLine if set, else build the command line by escaping
 276         // and joining each argument with spaces
 277         if sys.CmdLine != "" {
 278                 cmdline = sys.CmdLine
 279         } else {
 280                 cmdline = makeCmdLine(argv)
 281         }
 282
 283         var argvp *uint16
 284         if len(cmdline) != 0 {
 285                 argvp, err = UTF16PtrFromString(cmdline)
 286                 if err != nil {
 287                         return 0, 0, err
 288                 }
 289         }
 290
 291         var dirp *uint16
 292         if len(attr.Dir) != 0 {
 293                 dirp, err = UTF16PtrFromString(attr.Dir)
 294                 if err != nil {
 295                         return 0, 0, err
 296                 }
 297         }
 298
 299         // Acquire the fork lock so that no other threads
 300         // create new fds that are not yet close-on-exec
 301         // before we fork.
 302         ForkLock.Lock()
 303         defer ForkLock.Unlock()
 304
 305         p, _ := GetCurrentProcess()
 306         fd := make([]Handle, len(attr.Files))
 307         for i := range attr.Files {
 308                 if attr.Files[i] > 0 {
 309                         err := DuplicateHandle(p, Handle(attr.Files[i]), p, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
 310                         if err != nil {
 311                                 return 0, 0, err
 312                         }
 313                         defer CloseHandle(Handle(fd[i]))
 314                 }
 315         }
 316         si := new(StartupInfo)
 317         si.Cb = uint32(unsafe.Sizeof(*si))
 318         si.Flags = STARTF_USESTDHANDLES
 319         if sys.HideWindow {
 320                 si.Flags |= STARTF_USESHOWWINDOW
 321                 si.ShowWindow = SW_HIDE
 322         }
 323         si.StdInput = fd[0]
 324         si.StdOutput = fd[1]
 325         si.StdErr = fd[2]
 326
 327         pi := new(ProcessInformation)
 328
 329         flags := sys.CreationFlags | CREATE_UNICODE_ENVIRONMENT
 330         err = CreateProcess(argv0p, argvp, nil, nil, true, flags, createEnvBlock(attr.Env), dirp, si, pi)
 331         if err != nil {
 332                 return 0, 0, err
 333         }
 334         defer CloseHandle(Handle(pi.Thread))
 335
 336         return int(pi.ProcessId), uintptr(pi.Process), nil
 337 }
 338
 339 func Exec(argv0 string, argv []string, envv []string) (err error) {
 340         return EWINDOWS
 341 }