library/std/src/sys/windows/process.rs

   1 #![unstable(feature = "process_internals", issue = "none")]
   2
   3 #[cfg(test)]
   4 mod tests;
   5
   6 use crate::cmp;
   7 use crate::collections::BTreeMap;
   8 use crate::env;
   9 use crate::env::consts::{EXE_EXTENSION, EXE_SUFFIX};
  10 use crate::ffi::{OsStr, OsString};
  11 use crate::fmt;
  12 use crate::io::{self, Error, ErrorKind};
  13 use crate::mem;
  14 use crate::num::NonZeroI32;
  15 use crate::os::windows::ffi::{OsStrExt, OsStringExt};
  16 use crate::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle, FromRawHandle, IntoRawHandle};
  17 use crate::path::{Path, PathBuf};
  18 use crate::ptr;
  19 use crate::sync::Mutex;
  20 use crate::sys::args::{self, Arg};
  21 use crate::sys::c;
  22 use crate::sys::c::NonZeroDWORD;
  23 use crate::sys::cvt;
  24 use crate::sys::fs::{File, OpenOptions};
  25 use crate::sys::handle::Handle;
  26 use crate::sys::path;
  27 use crate::sys::pipe::{self, AnonPipe};
  28 use crate::sys::stdio;
  29 use crate::sys_common::process::{CommandEnv, CommandEnvs};
  30 use crate::sys_common::IntoInner;
  31
  32 use libc::{c_void, EXIT_FAILURE, EXIT_SUCCESS};
  33
  34 ////////////////////////////////////////////////////////////////////////////////
  35 // Command
  36 ////////////////////////////////////////////////////////////////////////////////
  37
  38 #[derive(Clone, Debug, Eq)]
  39 #[doc(hidden)]
  40 pub struct EnvKey {
  41     os_string: OsString,
  42     // This stores a UTF-16 encoded string to workaround the mismatch between
  43     // Rust's OsString (WTF-8) and the Windows API string type (UTF-16).
  44     // Normally converting on every API call is acceptable but here
  45     // `c::CompareStringOrdinal` will be called for every use of `==`.
  46     utf16: Vec<u16>,
  47 }
  48
  49 impl EnvKey {
  50     fn new<T: Into<OsString>>(key: T) -> Self {
  51         EnvKey::from(key.into())
  52     }
  53 }
  54
  55 // Comparing Windows environment variable keys[1] are behaviourally the
  56 // composition of two operations[2]:
  57 //
  58 // 1. Case-fold both strings. This is done using a language-independent
  59 // uppercase mapping that's unique to Windows (albeit based on data from an
  60 // older Unicode spec). It only operates on individual UTF-16 code units so
  61 // surrogates are left unchanged. This uppercase mapping can potentially change
  62 // between Windows versions.
  63 //
  64 // 2. Perform an ordinal comparison of the strings. A comparison using ordinal
  65 // is just a comparison based on the numerical value of each UTF-16 code unit[3].
  66 //
  67 // Because the case-folding mapping is unique to Windows and not guaranteed to
  68 // be stable, we ask the OS to compare the strings for us. This is done by
  69 // calling `CompareStringOrdinal`[4] with `bIgnoreCase` set to `TRUE`.
  70 //
  71 // [1] https://docs.microsoft.com/en-us/dotnet/standard/base-types/best-practices-strings#choosing-a-stringcomparison-member-for-your-method-call
  72 // [2] https://docs.microsoft.com/en-us/dotnet/standard/base-types/best-practices-strings#stringtoupper-and-stringtolower
  73 // [3] https://docs.microsoft.com/en-us/dotnet/api/system.stringcomparison?view=net-5.0#System_StringComparison_Ordinal
  74 // [4] https://docs.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-comparestringordinal
  75 impl Ord for EnvKey {
  76     fn cmp(&self, other: &Self) -> cmp::Ordering {
  77         unsafe {
  78             let result = c::CompareStringOrdinal(
  79                 self.utf16.as_ptr(),
  80                 self.utf16.len() as _,
  81                 other.utf16.as_ptr(),
  82                 other.utf16.len() as _,
  83                 c::TRUE,
  84             );
  85             match result {
  86                 c::CSTR_LESS_THAN => cmp::Ordering::Less,
  87                 c::CSTR_EQUAL => cmp::Ordering::Equal,
  88                 c::CSTR_GREATER_THAN => cmp::Ordering::Greater,
  89                 // `CompareStringOrdinal` should never fail so long as the parameters are correct.
  90                 _ => panic!("comparing environment keys failed: {}", Error::last_os_error()),
  91             }
  92         }
  93     }
  94 }
  95 impl PartialOrd for EnvKey {
  96     fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
  97         Some(self.cmp(other))
  98     }
  99 }
 100 impl PartialEq for EnvKey {
 101     fn eq(&self, other: &Self) -> bool {
 102         if self.utf16.len() != other.utf16.len() {
 103             false
 104         } else {
 105             self.cmp(other) == cmp::Ordering::Equal
 106         }
 107     }
 108 }
 109 impl PartialOrd<str> for EnvKey {
 110     fn partial_cmp(&self, other: &str) -> Option<cmp::Ordering> {
 111         Some(self.cmp(&EnvKey::new(other)))
 112     }
 113 }
 114 impl PartialEq<str> for EnvKey {
 115     fn eq(&self, other: &str) -> bool {
 116         if self.os_string.len() != other.len() {
 117             false
 118         } else {
 119             self.cmp(&EnvKey::new(other)) == cmp::Ordering::Equal
 120         }
 121     }
 122 }
 123
 124 // Environment variable keys should preserve their original case even though
 125 // they are compared using a caseless string mapping.
 126 impl From<OsString> for EnvKey {
 127     fn from(k: OsString) -> Self {
 128         EnvKey { utf16: k.encode_wide().collect(), os_string: k }
 129     }
 130 }
 131
 132 impl From<EnvKey> for OsString {
 133     fn from(k: EnvKey) -> Self {
 134         k.os_string
 135     }
 136 }
 137
 138 impl From<&OsStr> for EnvKey {
 139     fn from(k: &OsStr) -> Self {
 140         Self::from(k.to_os_string())
 141     }
 142 }
 143
 144 impl AsRef<OsStr> for EnvKey {
 145     fn as_ref(&self) -> &OsStr {
 146         &self.os_string
 147     }
 148 }
 149
 150 pub(crate) fn ensure_no_nuls<T: AsRef<OsStr>>(str: T) -> io::Result<T> {
 151     if str.as_ref().encode_wide().any(|b| b == 0) {
 152         Err(io::const_io_error!(ErrorKind::InvalidInput, "nul byte found in provided data"))
 153     } else {
 154         Ok(str)
 155     }
 156 }
 157
 158 pub struct Command {
 159     program: OsString,
 160     args: Vec<Arg>,
 161     env: CommandEnv,
 162     cwd: Option<OsString>,
 163     flags: u32,
 164     detach: bool, // not currently exposed in std::process
 165     stdin: Option<Stdio>,
 166     stdout: Option<Stdio>,
 167     stderr: Option<Stdio>,
 168     force_quotes_enabled: bool,
 169 }
 170
 171 pub enum Stdio {
 172     Inherit,
 173     Null,
 174     MakePipe,
 175     Pipe(AnonPipe),
 176     Handle(Handle),
 177 }
 178
 179 pub struct StdioPipes {
 180     pub stdin: Option<AnonPipe>,
 181     pub stdout: Option<AnonPipe>,
 182     pub stderr: Option<AnonPipe>,
 183 }
 184
 185 impl Command {
 186     pub fn new(program: &OsStr) -> Command {
 187         Command {
 188             program: program.to_os_string(),
 189             args: Vec::new(),
 190             env: Default::default(),
 191             cwd: None,
 192             flags: 0,
 193             detach: false,
 194             stdin: None,
 195             stdout: None,
 196             stderr: None,
 197             force_quotes_enabled: false,
 198         }
 199     }
 200
 201     pub fn arg(&mut self, arg: &OsStr) {
 202         self.args.push(Arg::Regular(arg.to_os_string()))
 203     }
 204     pub fn env_mut(&mut self) -> &mut CommandEnv {
 205         &mut self.env
 206     }
 207     pub fn cwd(&mut self, dir: &OsStr) {
 208         self.cwd = Some(dir.to_os_string())
 209     }
 210     pub fn stdin(&mut self, stdin: Stdio) {
 211         self.stdin = Some(stdin);
 212     }
 213     pub fn stdout(&mut self, stdout: Stdio) {
 214         self.stdout = Some(stdout);
 215     }
 216     pub fn stderr(&mut self, stderr: Stdio) {
 217         self.stderr = Some(stderr);
 218     }
 219     pub fn creation_flags(&mut self, flags: u32) {
 220         self.flags = flags;
 221     }
 222
 223     pub fn force_quotes(&mut self, enabled: bool) {
 224         self.force_quotes_enabled = enabled;
 225     }
 226
 227     pub fn raw_arg(&mut self, command_str_to_append: &OsStr) {
 228         self.args.push(Arg::Raw(command_str_to_append.to_os_string()))
 229     }
 230
 231     pub fn get_program(&self) -> &OsStr {
 232         &self.program
 233     }
 234
 235     pub fn get_args(&self) -> CommandArgs<'_> {
 236         let iter = self.args.iter();
 237         CommandArgs { iter }
 238     }
 239
 240     pub fn get_envs(&self) -> CommandEnvs<'_> {
 241         self.env.iter()
 242     }
 243
 244     pub fn get_current_dir(&self) -> Option<&Path> {
 245         self.cwd.as_ref().map(|cwd| Path::new(cwd))
 246     }
 247
 248     pub fn spawn(
 249         &mut self,
 250         default: Stdio,
 251         needs_stdin: bool,
 252     ) -> io::Result<(Process, StdioPipes)> {
 253         let maybe_env = self.env.capture_if_changed();
 254
 255         let child_paths = if let Some(env) = maybe_env.as_ref() {
 256             env.get(&EnvKey::new("PATH")).map(|s| s.as_os_str())
 257         } else {
 258             None
 259         };
 260         let program = resolve_exe(&self.program, || env::var_os("PATH"), child_paths)?;
 261         // Case insensitive "ends_with" of UTF-16 encoded ".bat" or ".cmd"
 262         let is_batch_file = matches!(
 263             program.len().checked_sub(5).and_then(|i| program.get(i..)),
 264             Some([46, 98 | 66, 97 | 65, 116 | 84, 0] | [46, 99 | 67, 109 | 77, 100 | 68, 0])
 265         );
 266         let (program, mut cmd_str) = if is_batch_file {
 267             (
 268                 command_prompt()?,
 269                 args::make_bat_command_line(&program, &self.args, self.force_quotes_enabled)?,
 270             )
 271         } else {
 272             let cmd_str = make_command_line(&self.program, &self.args, self.force_quotes_enabled)?;
 273             (program, cmd_str)
 274         };
 275         cmd_str.push(0); // add null terminator
 276
 277         // stolen from the libuv code.
 278         let mut flags = self.flags | c::CREATE_UNICODE_ENVIRONMENT;
 279         if self.detach {
 280             flags |= c::DETACHED_PROCESS | c::CREATE_NEW_PROCESS_GROUP;
 281         }
 282
 283         let (envp, _data) = make_envp(maybe_env)?;
 284         let (dirp, _data) = make_dirp(self.cwd.as_ref())?;
 285         let mut pi = zeroed_process_information();
 286
 287         // Prepare all stdio handles to be inherited by the child. This
 288         // currently involves duplicating any existing ones with the ability to
 289         // be inherited by child processes. Note, however, that once an
 290         // inheritable handle is created, *any* spawned child will inherit that
 291         // handle. We only want our own child to inherit this handle, so we wrap
 292         // the remaining portion of this spawn in a mutex.
 293         //
 294         // For more information, msdn also has an article about this race:
 295         // https://support.microsoft.com/kb/315939
 296         static CREATE_PROCESS_LOCK: Mutex<()> = Mutex::new(());
 297
 298         let _guard = CREATE_PROCESS_LOCK.lock();
 299
 300         let mut pipes = StdioPipes { stdin: None, stdout: None, stderr: None };
 301         let null = Stdio::Null;
 302         let default_stdin = if needs_stdin { &default } else { &null };
 303         let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
 304         let stdout = self.stdout.as_ref().unwrap_or(&default);
 305         let stderr = self.stderr.as_ref().unwrap_or(&default);
 306         let stdin = stdin.to_handle(c::STD_INPUT_HANDLE, &mut pipes.stdin)?;
 307         let stdout = stdout.to_handle(c::STD_OUTPUT_HANDLE, &mut pipes.stdout)?;
 308         let stderr = stderr.to_handle(c::STD_ERROR_HANDLE, &mut pipes.stderr)?;
 309
 310         let mut si = zeroed_startupinfo();
 311         si.cb = mem::size_of::<c::STARTUPINFOW>() as c::DWORD;
 312
 313         // If at least one of stdin, stdout or stderr are set (i.e. are non null)
 314         // then set the `hStd` fields in `STARTUPINFO`.
 315         // Otherwise skip this and allow the OS to apply its default behaviour.
 316         // This provides more consistent behaviour between Win7 and Win8+.
 317         let is_set = |stdio: &Handle| !stdio.as_raw_handle().is_null();
 318         if is_set(&stderr) || is_set(&stdout) || is_set(&stdin) {
 319             si.dwFlags |= c::STARTF_USESTDHANDLES;
 320             si.hStdInput = stdin.as_raw_handle();
 321             si.hStdOutput = stdout.as_raw_handle();
 322             si.hStdError = stderr.as_raw_handle();
 323         }
 324
 325         unsafe {
 326             cvt(c::CreateProcessW(
 327                 program.as_ptr(),
 328                 cmd_str.as_mut_ptr(),
 329                 ptr::null_mut(),
 330                 ptr::null_mut(),
 331                 c::TRUE,
 332                 flags,
 333                 envp,
 334                 dirp,
 335                 &si,
 336                 &mut pi,
 337             ))
 338         }?;
 339
 340         unsafe {
 341             Ok((
 342                 Process {
 343                     handle: Handle::from_raw_handle(pi.hProcess),
 344                     main_thread_handle: Handle::from_raw_handle(pi.hThread),
 345                 },
 346                 pipes,
 347             ))
 348         }
 349     }
 350
 351     pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> {
 352         let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?;
 353         crate::sys_common::process::wait_with_output(proc, pipes)
 354     }
 355 }
 356
 357 impl fmt::Debug for Command {
 358     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 359         self.program.fmt(f)?;
 360         for arg in &self.args {
 361             f.write_str(" ")?;
 362             match arg {
 363                 Arg::Regular(s) => s.fmt(f),
 364                 Arg::Raw(s) => f.write_str(&s.to_string_lossy()),
 365             }?;
 366         }
 367         Ok(())
 368     }
 369 }
 370
 371 // Resolve `exe_path` to the executable name.
 372 //
 373 // * If the path is simply a file name then use the paths given by `search_paths` to find the executable.
 374 // * Otherwise use the `exe_path` as given.
 375 //
 376 // This function may also append `.exe` to the name. The rationale for doing so is as follows:
 377 //
 378 // It is a very strong convention that Windows executables have the `exe` extension.
 379 // In Rust, it is common to omit this extension.
 380 // Therefore this functions first assumes `.exe` was intended.
 381 // It falls back to the plain file name if a full path is given and the extension is omitted
 382 // or if only a file name is given and it already contains an extension.
 383 fn resolve_exe<'a>(
 384     exe_path: &'a OsStr,
 385     parent_paths: impl FnOnce() -> Option<OsString>,
 386     child_paths: Option<&OsStr>,
 387 ) -> io::Result<Vec<u16>> {
 388     // Early return if there is no filename.
 389     if exe_path.is_empty() || path::has_trailing_slash(exe_path) {
 390         return Err(io::const_io_error!(
 391             io::ErrorKind::InvalidInput,
 392             "program path has no file name",
 393         ));
 394     }
 395     // Test if the file name has the `exe` extension.
 396     // This does a case-insensitive `ends_with`.
 397     let has_exe_suffix = if exe_path.len() >= EXE_SUFFIX.len() {
 398         exe_path.as_os_str_bytes()[exe_path.len() - EXE_SUFFIX.len()..]
 399             .eq_ignore_ascii_case(EXE_SUFFIX.as_bytes())
 400     } else {
 401         false
 402     };
 403
 404     // If `exe_path` is an absolute path or a sub-path then don't search `PATH` for it.
 405     if !path::is_file_name(exe_path) {
 406         if has_exe_suffix {
 407             // The application name is a path to a `.exe` file.
 408             // Let `CreateProcessW` figure out if it exists or not.
 409             return args::to_user_path(Path::new(exe_path));
 410         }
 411         let mut path = PathBuf::from(exe_path);
 412
 413         // Append `.exe` if not already there.
 414         path = path::append_suffix(path, EXE_SUFFIX.as_ref());
 415         if let Some(path) = program_exists(&path) {
 416             return Ok(path);
 417         } else {
 418             // It's ok to use `set_extension` here because the intent is to
 419             // remove the extension that was just added.
 420             path.set_extension("");
 421             return args::to_user_path(&path);
 422         }
 423     } else {
 424         ensure_no_nuls(exe_path)?;
 425         // From the `CreateProcessW` docs:
 426         // > If the file name does not contain an extension, .exe is appended.
 427         // Note that this rule only applies when searching paths.
 428         let has_extension = exe_path.as_os_str_bytes().contains(&b'.');
 429
 430         // Search the directories given by `search_paths`.
 431         let result = search_paths(parent_paths, child_paths, |mut path| {
 432             path.push(&exe_path);
 433             if !has_extension {
 434                 path.set_extension(EXE_EXTENSION);
 435             }
 436             program_exists(&path)
 437         });
 438         if let Some(path) = result {
 439             return Ok(path);
 440         }
 441     }
 442     // If we get here then the executable cannot be found.
 443     Err(io::const_io_error!(io::ErrorKind::NotFound, "program not found"))
 444 }
 445
 446 // Calls `f` for every path that should be used to find an executable.
 447 // Returns once `f` returns the path to an executable or all paths have been searched.
 448 fn search_paths<Paths, Exists>(
 449     parent_paths: Paths,
 450     child_paths: Option<&OsStr>,
 451     mut exists: Exists,
 452 ) -> Option<Vec<u16>>
 453 where
 454     Paths: FnOnce() -> Option<OsString>,
 455     Exists: FnMut(PathBuf) -> Option<Vec<u16>>,
 456 {
 457     // 1. Child paths
 458     // This is for consistency with Rust's historic behaviour.
 459     if let Some(paths) = child_paths {
 460         for path in env::split_paths(paths).filter(|p| !p.as_os_str().is_empty()) {
 461             if let Some(path) = exists(path) {
 462                 return Some(path);
 463             }
 464         }
 465     }
 466
 467     // 2. Application path
 468     if let Ok(mut app_path) = env::current_exe() {
 469         app_path.pop();
 470         if let Some(path) = exists(app_path) {
 471             return Some(path);
 472         }
 473     }
 474
 475     // 3 & 4. System paths
 476     // SAFETY: This uses `fill_utf16_buf` to safely call the OS functions.
 477     unsafe {
 478         if let Ok(Some(path)) = super::fill_utf16_buf(
 479             |buf, size| c::GetSystemDirectoryW(buf, size),
 480             |buf| exists(PathBuf::from(OsString::from_wide(buf))),
 481         ) {
 482             return Some(path);
 483         }
 484         #[cfg(not(target_vendor = "uwp"))]
 485         {
 486             if let Ok(Some(path)) = super::fill_utf16_buf(
 487                 |buf, size| c::GetWindowsDirectoryW(buf, size),
 488                 |buf| exists(PathBuf::from(OsString::from_wide(buf))),
 489             ) {
 490                 return Some(path);
 491             }
 492         }
 493     }
 494
 495     // 5. Parent paths
 496     if let Some(parent_paths) = parent_paths() {
 497         for path in env::split_paths(&parent_paths).filter(|p| !p.as_os_str().is_empty()) {
 498             if let Some(path) = exists(path) {
 499                 return Some(path);
 500             }
 501         }
 502     }
 503     None
 504 }
 505
 506 /// Check if a file exists without following symlinks.
 507 fn program_exists(path: &Path) -> Option<Vec<u16>> {
 508     unsafe {
 509         let path = args::to_user_path(path).ok()?;
 510         // Getting attributes using `GetFileAttributesW` does not follow symlinks
 511         // and it will almost always be successful if the link exists.
 512         // There are some exceptions for special system files (e.g. the pagefile)
 513         // but these are not executable.
 514         if c::GetFileAttributesW(path.as_ptr()) == c::INVALID_FILE_ATTRIBUTES {
 515             None
 516         } else {
 517             Some(path)
 518         }
 519     }
 520 }
 521
 522 impl Stdio {
 523     fn to_handle(&self, stdio_id: c::DWORD, pipe: &mut Option<AnonPipe>) -> io::Result<Handle> {
 524         match *self {
 525             Stdio::Inherit => match stdio::get_handle(stdio_id) {
 526                 Ok(io) => unsafe {
 527                     let io = Handle::from_raw_handle(io);
 528                     let ret = io.duplicate(0, true, c::DUPLICATE_SAME_ACCESS);
 529                     io.into_raw_handle();
 530                     ret
 531                 },
 532                 // If no stdio handle is available, then propagate the null value.
 533                 Err(..) => unsafe { Ok(Handle::from_raw_handle(ptr::null_mut())) },
 534             },
 535
 536             Stdio::MakePipe => {
 537                 let ours_readable = stdio_id != c::STD_INPUT_HANDLE;
 538                 let pipes = pipe::anon_pipe(ours_readable, true)?;
 539                 *pipe = Some(pipes.ours);
 540                 Ok(pipes.theirs.into_handle())
 541             }
 542
 543             Stdio::Pipe(ref source) => {
 544                 let ours_readable = stdio_id != c::STD_INPUT_HANDLE;
 545                 pipe::spawn_pipe_relay(source, ours_readable, true).map(AnonPipe::into_handle)
 546             }
 547
 548             Stdio::Handle(ref handle) => handle.duplicate(0, true, c::DUPLICATE_SAME_ACCESS),
 549
 550             // Open up a reference to NUL with appropriate read/write
 551             // permissions as well as the ability to be inherited to child
 552             // processes (as this is about to be inherited).
 553             Stdio::Null => {
 554                 let size = mem::size_of::<c::SECURITY_ATTRIBUTES>();
 555                 let mut sa = c::SECURITY_ATTRIBUTES {
 556                     nLength: size as c::DWORD,
 557                     lpSecurityDescriptor: ptr::null_mut(),
 558                     bInheritHandle: 1,
 559                 };
 560                 let mut opts = OpenOptions::new();
 561                 opts.read(stdio_id == c::STD_INPUT_HANDLE);
 562                 opts.write(stdio_id != c::STD_INPUT_HANDLE);
 563                 opts.security_attributes(&mut sa);
 564                 File::open(Path::new("NUL"), &opts).map(|file| file.into_inner())
 565             }
 566         }
 567     }
 568 }
 569
 570 impl From<AnonPipe> for Stdio {
 571     fn from(pipe: AnonPipe) -> Stdio {
 572         Stdio::Pipe(pipe)
 573     }
 574 }
 575
 576 impl From<File> for Stdio {
 577     fn from(file: File) -> Stdio {
 578         Stdio::Handle(file.into_inner())
 579     }
 580 }
 581
 582 ////////////////////////////////////////////////////////////////////////////////
 583 // Processes
 584 ////////////////////////////////////////////////////////////////////////////////
 585
 586 /// A value representing a child process.
 587 ///
 588 /// The lifetime of this value is linked to the lifetime of the actual
 589 /// process - the Process destructor calls self.finish() which waits
 590 /// for the process to terminate.
 591 pub struct Process {
 592     handle: Handle,
 593     main_thread_handle: Handle,
 594 }
 595
 596 impl Process {
 597     pub fn kill(&mut self) -> io::Result<()> {
 598         let result = unsafe { c::TerminateProcess(self.handle.as_raw_handle(), 1) };
 599         if result == c::FALSE {
 600             let error = unsafe { c::GetLastError() };
 601             // TerminateProcess returns ERROR_ACCESS_DENIED if the process has already been
 602             // terminated (by us, or for any other reason). So check if the process was actually
 603             // terminated, and if so, do not return an error.
 604             if error != c::ERROR_ACCESS_DENIED || self.try_wait().is_err() {
 605                 return Err(crate::io::Error::from_raw_os_error(error as i32));
 606             }
 607         }
 608         Ok(())
 609     }
 610
 611     pub fn id(&self) -> u32 {
 612         unsafe { c::GetProcessId(self.handle.as_raw_handle()) as u32 }
 613     }
 614
 615     pub fn main_thread_handle(&self) -> BorrowedHandle<'_> {
 616         self.main_thread_handle.as_handle()
 617     }
 618
 619     pub fn wait(&mut self) -> io::Result<ExitStatus> {
 620         unsafe {
 621             let res = c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE);
 622             if res != c::WAIT_OBJECT_0 {
 623                 return Err(Error::last_os_error());
 624             }
 625             let mut status = 0;
 626             cvt(c::GetExitCodeProcess(self.handle.as_raw_handle(), &mut status))?;
 627             Ok(ExitStatus(status))
 628         }
 629     }
 630
 631     pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
 632         unsafe {
 633             match c::WaitForSingleObject(self.handle.as_raw_handle(), 0) {
 634                 c::WAIT_OBJECT_0 => {}
 635                 c::WAIT_TIMEOUT => {
 636                     return Ok(None);
 637                 }
 638                 _ => return Err(io::Error::last_os_error()),
 639             }
 640             let mut status = 0;
 641             cvt(c::GetExitCodeProcess(self.handle.as_raw_handle(), &mut status))?;
 642             Ok(Some(ExitStatus(status)))
 643         }
 644     }
 645
 646     pub fn handle(&self) -> &Handle {
 647         &self.handle
 648     }
 649
 650     pub fn into_handle(self) -> Handle {
 651         self.handle
 652     }
 653 }
 654
 655 #[derive(PartialEq, Eq, Clone, Copy, Debug, Default)]
 656 pub struct ExitStatus(c::DWORD);
 657
 658 impl ExitStatus {
 659     pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
 660         match NonZeroDWORD::try_from(self.0) {
 661             /* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)),
 662             /* was zero, couldn't convert */ Err(_) => Ok(()),
 663         }
 664     }
 665     pub fn code(&self) -> Option<i32> {
 666         Some(self.0 as i32)
 667     }
 668 }
 669
 670 /// Converts a raw `c::DWORD` to a type-safe `ExitStatus` by wrapping it without copying.
 671 impl From<c::DWORD> for ExitStatus {
 672     fn from(u: c::DWORD) -> ExitStatus {
 673         ExitStatus(u)
 674     }
 675 }
 676
 677 impl fmt::Display for ExitStatus {
 678     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 679         // Windows exit codes with the high bit set typically mean some form of
 680         // unhandled exception or warning. In this scenario printing the exit
 681         // code in decimal doesn't always make sense because it's a very large
 682         // and somewhat gibberish number. The hex code is a bit more
 683         // recognizable and easier to search for, so print that.
 684         if self.0 & 0x80000000 != 0 {
 685             write!(f, "exit code: {:#x}", self.0)
 686         } else {
 687             write!(f, "exit code: {}", self.0)
 688         }
 689     }
 690 }
 691
 692 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
 693 pub struct ExitStatusError(c::NonZeroDWORD);
 694
 695 impl Into<ExitStatus> for ExitStatusError {
 696     fn into(self) -> ExitStatus {
 697         ExitStatus(self.0.into())
 698     }
 699 }
 700
 701 impl ExitStatusError {
 702     pub fn code(self) -> Option<NonZeroI32> {
 703         Some((u32::from(self.0) as i32).try_into().unwrap())
 704     }
 705 }
 706
 707 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
 708 pub struct ExitCode(c::DWORD);
 709
 710 impl ExitCode {
 711     pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
 712     pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
 713
 714     #[inline]
 715     pub fn as_i32(&self) -> i32 {
 716         self.0 as i32
 717     }
 718 }
 719
 720 impl From<u8> for ExitCode {
 721     fn from(code: u8) -> Self {
 722         ExitCode(c::DWORD::from(code))
 723     }
 724 }
 725
 726 impl From<u32> for ExitCode {
 727     fn from(code: u32) -> Self {
 728         ExitCode(c::DWORD::from(code))
 729     }
 730 }
 731
 732 fn zeroed_startupinfo() -> c::STARTUPINFOW {
 733     c::STARTUPINFOW {
 734         cb: 0,
 735         lpReserved: ptr::null_mut(),
 736         lpDesktop: ptr::null_mut(),
 737         lpTitle: ptr::null_mut(),
 738         dwX: 0,
 739         dwY: 0,
 740         dwXSize: 0,
 741         dwYSize: 0,
 742         dwXCountChars: 0,
 743         dwYCountChars: 0,
 744         dwFillAttribute: 0,
 745         dwFlags: 0,
 746         wShowWindow: 0,
 747         cbReserved2: 0,
 748         lpReserved2: ptr::null_mut(),
 749         hStdInput: ptr::null_mut(),
 750         hStdOutput: ptr::null_mut(),
 751         hStdError: ptr::null_mut(),
 752     }
 753 }
 754
 755 fn zeroed_process_information() -> c::PROCESS_INFORMATION {
 756     c::PROCESS_INFORMATION {
 757         hProcess: ptr::null_mut(),
 758         hThread: ptr::null_mut(),
 759         dwProcessId: 0,
 760         dwThreadId: 0,
 761     }
 762 }
 763
 764 // Produces a wide string *without terminating null*; returns an error if
 765 // `prog` or any of the `args` contain a nul.
 766 fn make_command_line(argv0: &OsStr, args: &[Arg], force_quotes: bool) -> io::Result<Vec<u16>> {
 767     // Encode the command and arguments in a command line string such
 768     // that the spawned process may recover them using CommandLineToArgvW.
 769     let mut cmd: Vec<u16> = Vec::new();
 770
 771     // Always quote the program name so CreateProcess to avoid ambiguity when
 772     // the child process parses its arguments.
 773     // Note that quotes aren't escaped here because they can't be used in arg0.
 774     // But that's ok because file paths can't contain quotes.
 775     cmd.push(b'"' as u16);
 776     cmd.extend(argv0.encode_wide());
 777     cmd.push(b'"' as u16);
 778
 779     for arg in args {
 780         cmd.push(' ' as u16);
 781         args::append_arg(&mut cmd, arg, force_quotes)?;
 782     }
 783     Ok(cmd)
 784 }
 785
 786 // Get `cmd.exe` for use with bat scripts, encoded as a UTF-16 string.
 787 fn command_prompt() -> io::Result<Vec<u16>> {
 788     let mut system: Vec<u16> = super::fill_utf16_buf(
 789         |buf, size| unsafe { c::GetSystemDirectoryW(buf, size) },
 790         |buf| buf.into(),
 791     )?;
 792     system.extend("\\cmd.exe".encode_utf16().chain([0]));
 793     Ok(system)
 794 }
 795
 796 fn make_envp(maybe_env: Option<BTreeMap<EnvKey, OsString>>) -> io::Result<(*mut c_void, Vec<u16>)> {
 797     // On Windows we pass an "environment block" which is not a char**, but
 798     // rather a concatenation of null-terminated k=v\0 sequences, with a final
 799     // \0 to terminate.
 800     if let Some(env) = maybe_env {
 801         let mut blk = Vec::new();
 802
 803         // If there are no environment variables to set then signal this by
 804         // pushing a null.
 805         if env.is_empty() {
 806             blk.push(0);
 807         }
 808
 809         for (k, v) in env {
 810             ensure_no_nuls(k.os_string)?;
 811             blk.extend(k.utf16);
 812             blk.push('=' as u16);
 813             blk.extend(ensure_no_nuls(v)?.encode_wide());
 814             blk.push(0);
 815         }
 816         blk.push(0);
 817         Ok((blk.as_mut_ptr() as *mut c_void, blk))
 818     } else {
 819         Ok((ptr::null_mut(), Vec::new()))
 820     }
 821 }
 822
 823 fn make_dirp(d: Option<&OsString>) -> io::Result<(*const u16, Vec<u16>)> {
 824     match d {
 825         Some(dir) => {
 826             let mut dir_str: Vec<u16> = ensure_no_nuls(dir)?.encode_wide().collect();
 827             dir_str.push(0);
 828             Ok((dir_str.as_ptr(), dir_str))
 829         }
 830         None => Ok((ptr::null(), Vec::new())),
 831     }
 832 }
 833
 834 pub struct CommandArgs<'a> {
 835     iter: crate::slice::Iter<'a, Arg>,
 836 }
 837
 838 impl<'a> Iterator for CommandArgs<'a> {
 839     type Item = &'a OsStr;
 840     fn next(&mut self) -> Option<&'a OsStr> {
 841         self.iter.next().map(|arg| match arg {
 842             Arg::Regular(s) | Arg::Raw(s) => s.as_ref(),
 843         })
 844     }
 845     fn size_hint(&self) -> (usize, Option<usize>) {
 846         self.iter.size_hint()
 847     }
 848 }
 849
 850 impl<'a> ExactSizeIterator for CommandArgs<'a> {
 851     fn len(&self) -> usize {
 852         self.iter.len()
 853     }
 854     fn is_empty(&self) -> bool {
 855         self.iter.is_empty()
 856     }
 857 }
 858
 859 impl<'a> fmt::Debug for CommandArgs<'a> {
 860     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 861         f.debug_list().entries(self.iter.clone()).finish()
 862     }
 863 }