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 } 338
