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 // FullPath retrieves the full path of the specified file.
 133 func FullPath(name string) (path string, err error) {
 134         p, err := UTF16PtrFromString(name)
 135         if err != nil {
 136                 return "", err
 137         }
 138         n := uint32(100)
 139         for {
 140                 buf := make([]uint16, n)
 141                 n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
 142                 if err != nil {
 143                         return "", err
 144                 }
 145                 if n <= uint32(len(buf)) {
 146                         return UTF16ToString(buf[:n]), nil
 147                 }
 148         }
 149 }
 150
 151 func isSlash(c uint8) bool {
 152         return c == '\\' || c == '/'
 153 }
 154
 155 func normalizeDir(dir string) (name string, err error) {
 156         ndir, err := FullPath(dir)
 157         if err != nil {
 158                 return "", err
 159         }
 160         if len(ndir) > 2 && isSlash(ndir[0]) && isSlash(ndir[1]) {
 161                 // dir cannot have \\server\share\path form
 162                 return "", EINVAL
 163         }
 164         return ndir, nil
 165 }
 166
 167 func volToUpper(ch int) int {
 168         if 'a' <= ch && ch <= 'z' {
 169                 ch += 'A' - 'a'
 170         }
 171         return ch
 172 }
 173
 174 func joinExeDirAndFName(dir, p string) (name string, err error) {
 175         if len(p) == 0 {
 176                 return "", EINVAL
 177         }
 178         if len(p) > 2 && isSlash(p[0]) && isSlash(p[1]) {
 179                 // \\server\share\path form
 180                 return p, nil
 181         }
 182         if len(p) > 1 && p[1] == ':' {
 183                 // has drive letter
 184                 if len(p) == 2 {
 185                         return "", EINVAL
 186                 }
 187                 if isSlash(p[2]) {
 188                         return p, nil
 189                 } else {
 190                         d, err := normalizeDir(dir)
 191                         if err != nil {
 192                                 return "", err
 193                         }
 194                         if volToUpper(int(p[0])) == volToUpper(int(d[0])) {
 195                                 return FullPath(d + "\\" + p[2:])
 196                         } else {
 197                                 return FullPath(p)
 198                         }
 199                 }
 200         } else {
 201                 // no drive letter
 202                 d, err := normalizeDir(dir)
 203                 if err != nil {
 204                         return "", err
 205                 }
 206                 if isSlash(p[0]) {
 207                         return FullPath(d[:2] + p)
 208                 } else {
 209                         return FullPath(d + "\\" + p)
 210                 }
 211         }
 212         // we shouldn't be here
 213         return "", EINVAL
 214 }
 215
 216 type ProcAttr struct {
 217         Dir   string
 218         Env   []string
 219         Files []uintptr
 220         Sys   *SysProcAttr
 221 }
 222
 223 type SysProcAttr struct {
 224         HideWindow    bool
 225         CmdLine       string // used if non-empty, else the windows command line is built by escaping the arguments passed to StartProcess
 226         CreationFlags uint32
 227 }
 228
 229 var zeroProcAttr ProcAttr
 230 var zeroSysProcAttr SysProcAttr
 231
 232 func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error) {
 233         if len(argv0) == 0 {
 234                 return 0, 0, EWINDOWS
 235         }
 236         if attr == nil {
 237                 attr = &zeroProcAttr
 238         }
 239         sys := attr.Sys
 240         if sys == nil {
 241                 sys = &zeroSysProcAttr
 242         }
 243
 244         if len(attr.Files) > 3 {
 245                 return 0, 0, EWINDOWS
 246         }
 247         if len(attr.Files) < 3 {
 248                 return 0, 0, EINVAL
 249         }
 250
 251         if len(attr.Dir) != 0 {
 252                 // StartProcess assumes that argv0 is relative to attr.Dir,
 253                 // because it implies Chdir(attr.Dir) before executing argv0.
 254                 // Windows CreateProcess assumes the opposite: it looks for
 255                 // argv0 relative to the current directory, and, only once the new
 256                 // process is started, it does Chdir(attr.Dir). We are adjusting
 257                 // for that difference here by making argv0 absolute.
 258                 var err error
 259                 argv0, err = joinExeDirAndFName(attr.Dir, argv0)
 260                 if err != nil {
 261                         return 0, 0, err
 262                 }
 263         }
 264         argv0p, err := UTF16PtrFromString(argv0)
 265         if err != nil {
 266                 return 0, 0, err
 267         }
 268
 269         var cmdline string
 270         // Windows CreateProcess takes the command line as a single string:
 271         // use attr.CmdLine if set, else build the command line by escaping
 272         // and joining each argument with spaces
 273         if sys.CmdLine != "" {
 274                 cmdline = sys.CmdLine
 275         } else {
 276                 cmdline = makeCmdLine(argv)
 277         }
 278
 279         var argvp *uint16
 280         if len(cmdline) != 0 {
 281                 argvp, err = UTF16PtrFromString(cmdline)
 282                 if err != nil {
 283                         return 0, 0, err
 284                 }
 285         }
 286
 287         var dirp *uint16
 288         if len(attr.Dir) != 0 {
 289                 dirp, err = UTF16PtrFromString(attr.Dir)
 290                 if err != nil {
 291                         return 0, 0, err
 292                 }
 293         }
 294
 295         // Acquire the fork lock so that no other threads
 296         // create new fds that are not yet close-on-exec
 297         // before we fork.
 298         ForkLock.Lock()
 299         defer ForkLock.Unlock()
 300
 301         p, _ := GetCurrentProcess()
 302         fd := make([]Handle, len(attr.Files))
 303         for i := range attr.Files {
 304                 if attr.Files[i] > 0 {
 305                         err := DuplicateHandle(p, Handle(attr.Files[i]), p, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
 306                         if err != nil {
 307                                 return 0, 0, err
 308                         }
 309                         defer CloseHandle(Handle(fd[i]))
 310                 }
 311         }
 312         si := new(StartupInfo)
 313         si.Cb = uint32(unsafe.Sizeof(*si))
 314         si.Flags = STARTF_USESTDHANDLES
 315         if sys.HideWindow {
 316                 si.Flags |= STARTF_USESHOWWINDOW
 317                 si.ShowWindow = SW_HIDE
 318         }
 319         si.StdInput = fd[0]
 320         si.StdOutput = fd[1]
 321         si.StdErr = fd[2]
 322
 323         pi := new(ProcessInformation)
 324
 325         flags := sys.CreationFlags | CREATE_UNICODE_ENVIRONMENT
 326         err = CreateProcess(argv0p, argvp, nil, nil, true, flags, createEnvBlock(attr.Env), dirp, si, pi)
 327         if err != nil {
 328                 return 0, 0, err
 329         }
 330         defer CloseHandle(Handle(pi.Thread))
 331
 332         return int(pi.ProcessId), uintptr(pi.Process), nil
 333 }
 334
 335 func Exec(argv0 string, argv []string, envv []string) (err error) {
 336         return EWINDOWS
 337 }