1 #![unstable(feature = "process_internals", issue = "none")]
7 use crate::collections::BTreeMap;
8 use crate::convert::{TryFrom, TryInto};
10 use crate::env::consts::{EXE_EXTENSION, EXE_SUFFIX};
11 use crate::ffi::{OsStr, OsString};
13 use crate::io::{self, Error, ErrorKind};
15 use crate::num::NonZeroI32;
16 use crate::os::windows::ffi::{OsStrExt, OsStringExt};
17 use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle};
18 use crate::path::{Path, PathBuf};
21 use crate::sys::c::NonZeroDWORD;
22 use crate::sys::fs::{File, OpenOptions};
23 use crate::sys::handle::Handle;
25 use crate::sys::pipe::{self, AnonPipe};
26 use crate::sys::stdio;
27 use crate::sys::{cvt, to_u16s};
28 use crate::sys_common::mutex::StaticMutex;
29 use crate::sys_common::process::{CommandEnv, CommandEnvs};
30 use crate::sys_common::{AsInner, IntoInner};
32 use libc::{c_void, EXIT_FAILURE, EXIT_SUCCESS};
34 ////////////////////////////////////////////////////////////////////////////////
36 ////////////////////////////////////////////////////////////////////////////////
38 #[derive(Clone, Debug, Eq)]
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 `==`.
50 fn new<T: Into<OsString>>(key: T) -> Self {
51 EnvKey::from(key.into())
55 // Comparing Windows environment variable keys[1] are behaviourally the
56 // composition of two operations[2]:
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.
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].
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`.
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
76 fn cmp(&self, other: &Self) -> cmp::Ordering {
78 let result = c::CompareStringOrdinal(
80 self.utf16.len() as _,
82 other.utf16.len() as _,
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()),
95 impl PartialOrd for EnvKey {
96 fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
100 impl PartialEq for EnvKey {
101 fn eq(&self, other: &Self) -> bool {
102 if self.utf16.len() != other.utf16.len() {
105 self.cmp(other) == cmp::Ordering::Equal
109 impl PartialOrd<str> for EnvKey {
110 fn partial_cmp(&self, other: &str) -> Option<cmp::Ordering> {
111 Some(self.cmp(&EnvKey::new(other)))
114 impl PartialEq<str> for EnvKey {
115 fn eq(&self, other: &str) -> bool {
116 if self.os_string.len() != other.len() {
119 self.cmp(&EnvKey::new(other)) == cmp::Ordering::Equal
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 }
132 impl From<EnvKey> for OsString {
133 fn from(k: EnvKey) -> Self {
138 impl From<&OsStr> for EnvKey {
139 fn from(k: &OsStr) -> Self {
140 Self::from(k.to_os_string())
144 impl AsRef<OsStr> for EnvKey {
145 fn as_ref(&self) -> &OsStr {
150 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::Error::new_const(ErrorKind::InvalidInput, &"nul byte found in provided data"))
162 cwd: Option<OsString>,
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,
178 pub struct StdioPipes {
179 pub stdin: Option<AnonPipe>,
180 pub stdout: Option<AnonPipe>,
181 pub stderr: Option<AnonPipe>,
186 /// Add quotes (if needed)
188 /// Append raw string without quoting
193 pub fn new(program: &OsStr) -> Command {
195 program: program.to_os_string(),
197 env: Default::default(),
204 force_quotes_enabled: false,
208 pub fn arg(&mut self, arg: &OsStr) {
209 self.args.push(Arg::Regular(arg.to_os_string()))
211 pub fn env_mut(&mut self) -> &mut CommandEnv {
214 pub fn cwd(&mut self, dir: &OsStr) {
215 self.cwd = Some(dir.to_os_string())
217 pub fn stdin(&mut self, stdin: Stdio) {
218 self.stdin = Some(stdin);
220 pub fn stdout(&mut self, stdout: Stdio) {
221 self.stdout = Some(stdout);
223 pub fn stderr(&mut self, stderr: Stdio) {
224 self.stderr = Some(stderr);
226 pub fn creation_flags(&mut self, flags: u32) {
230 pub fn force_quotes(&mut self, enabled: bool) {
231 self.force_quotes_enabled = enabled;
234 pub fn raw_arg(&mut self, command_str_to_append: &OsStr) {
235 self.args.push(Arg::Raw(command_str_to_append.to_os_string()))
238 pub fn get_program(&self) -> &OsStr {
242 pub fn get_args(&self) -> CommandArgs<'_> {
243 let iter = self.args.iter();
247 pub fn get_envs(&self) -> CommandEnvs<'_> {
251 pub fn get_current_dir(&self) -> Option<&Path> {
252 self.cwd.as_ref().map(|cwd| Path::new(cwd))
259 ) -> io::Result<(Process, StdioPipes)> {
260 let maybe_env = self.env.capture_if_changed();
262 let mut si = zeroed_startupinfo();
263 si.cb = mem::size_of::<c::STARTUPINFO>() as c::DWORD;
264 si.dwFlags = c::STARTF_USESTDHANDLES;
266 let child_paths = if let Some(env) = maybe_env.as_ref() {
267 env.get(&EnvKey::new("PATH")).map(|s| s.as_os_str())
271 let program = resolve_exe(&self.program, || env::var_os("PATH"), child_paths)?;
273 make_command_line(program.as_os_str(), &self.args, self.force_quotes_enabled)?;
274 cmd_str.push(0); // add null terminator
276 // stolen from the libuv code.
277 let mut flags = self.flags | c::CREATE_UNICODE_ENVIRONMENT;
279 flags |= c::DETACHED_PROCESS | c::CREATE_NEW_PROCESS_GROUP;
282 let (envp, _data) = make_envp(maybe_env)?;
283 let (dirp, _data) = make_dirp(self.cwd.as_ref())?;
284 let mut pi = zeroed_process_information();
286 // Prepare all stdio handles to be inherited by the child. This
287 // currently involves duplicating any existing ones with the ability to
288 // be inherited by child processes. Note, however, that once an
289 // inheritable handle is created, *any* spawned child will inherit that
290 // handle. We only want our own child to inherit this handle, so we wrap
291 // the remaining portion of this spawn in a mutex.
293 // For more information, msdn also has an article about this race:
294 // https://support.microsoft.com/kb/315939
295 static CREATE_PROCESS_LOCK: StaticMutex = StaticMutex::new();
297 let _guard = unsafe { CREATE_PROCESS_LOCK.lock() };
299 let mut pipes = StdioPipes { stdin: None, stdout: None, stderr: None };
300 let null = Stdio::Null;
301 let default_stdin = if needs_stdin { &default } else { &null };
302 let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
303 let stdout = self.stdout.as_ref().unwrap_or(&default);
304 let stderr = self.stderr.as_ref().unwrap_or(&default);
305 let stdin = stdin.to_handle(c::STD_INPUT_HANDLE, &mut pipes.stdin)?;
306 let stdout = stdout.to_handle(c::STD_OUTPUT_HANDLE, &mut pipes.stdout)?;
307 let stderr = stderr.to_handle(c::STD_ERROR_HANDLE, &mut pipes.stderr)?;
308 si.hStdInput = stdin.as_raw_handle();
309 si.hStdOutput = stdout.as_raw_handle();
310 si.hStdError = stderr.as_raw_handle();
312 let program = to_u16s(&program)?;
314 cvt(c::CreateProcessW(
316 cmd_str.as_mut_ptr(),
328 // We close the thread handle because we don't care about keeping
329 // the thread id valid, and we aren't keeping the thread handle
330 // around to be able to close it later.
332 drop(Handle::from_raw_handle(pi.hThread));
334 Ok((Process { handle: Handle::from_raw_handle(pi.hProcess) }, pipes))
339 impl fmt::Debug for Command {
340 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
341 self.program.fmt(f)?;
342 for arg in &self.args {
345 Arg::Regular(s) => s.fmt(f),
346 Arg::Raw(s) => f.write_str(&s.to_string_lossy()),
353 // Resolve `exe_path` to the executable name.
355 // * If the path is simply a file name then use the paths given by `search_paths` to find the executable.
356 // * Otherwise use the `exe_path` as given.
358 // This function may also append `.exe` to the name. The rationale for doing so is as follows:
360 // It is a very strong convention that Windows executables have the `exe` extension.
361 // In Rust, it is common to omit this extension.
362 // Therefore this functions first assumes `.exe` was intended.
363 // It falls back to the plain file name if a full path is given and the extension is omitted
364 // or if only a file name is given and it already contains an extension.
367 parent_paths: impl FnOnce() -> Option<OsString>,
368 child_paths: Option<&OsStr>,
369 ) -> io::Result<PathBuf> {
370 // Early return if there is no filename.
371 if exe_path.is_empty() || path::has_trailing_slash(exe_path) {
372 return Err(io::Error::new_const(
373 io::ErrorKind::InvalidInput,
374 &"program path has no file name",
377 // Test if the file name has the `exe` extension.
378 // This does a case-insensitive `ends_with`.
379 let has_exe_suffix = if exe_path.len() >= EXE_SUFFIX.len() {
380 exe_path.bytes()[exe_path.len() - EXE_SUFFIX.len()..]
381 .eq_ignore_ascii_case(EXE_SUFFIX.as_bytes())
386 // If `exe_path` is an absolute path or a sub-path then don't search `PATH` for it.
387 if !path::is_file_name(exe_path) {
389 // The application name is a path to a `.exe` file.
390 // Let `CreateProcessW` figure out if it exists or not.
391 return Ok(exe_path.into());
393 let mut path = PathBuf::from(exe_path);
395 // Append `.exe` if not already there.
396 path = path::append_suffix(path, EXE_SUFFIX.as_ref());
397 if path.try_exists().unwrap_or(false) {
400 // It's ok to use `set_extension` here because the intent is to
401 // remove the extension that was just added.
402 path.set_extension("");
406 ensure_no_nuls(exe_path)?;
407 // From the `CreateProcessW` docs:
408 // > If the file name does not contain an extension, .exe is appended.
409 // Note that this rule only applies when searching paths.
410 let has_extension = exe_path.bytes().contains(&b'.');
412 // Search the directories given by `search_paths`.
413 let result = search_paths(parent_paths, child_paths, |mut path| {
414 path.push(&exe_path);
416 path.set_extension(EXE_EXTENSION);
418 if let Ok(true) = path.try_exists() { Some(path) } else { None }
420 if let Some(path) = result {
424 // If we get here then the executable cannot be found.
425 Err(io::Error::new_const(io::ErrorKind::NotFound, &"program not found"))
428 // Calls `f` for every path that should be used to find an executable.
429 // Returns once `f` returns the path to an executable or all paths have been searched.
430 fn search_paths<Paths, Exists>(
432 child_paths: Option<&OsStr>,
436 Paths: FnOnce() -> Option<OsString>,
437 Exists: FnMut(PathBuf) -> Option<PathBuf>,
440 // This is for consistency with Rust's historic behaviour.
441 if let Some(paths) = child_paths {
442 for path in env::split_paths(paths).filter(|p| !p.as_os_str().is_empty()) {
443 if let Some(path) = exists(path) {
449 // 2. Application path
450 if let Ok(mut app_path) = env::current_exe() {
452 if let Some(path) = exists(app_path) {
457 // 3 & 4. System paths
458 // SAFETY: This uses `fill_utf16_buf` to safely call the OS functions.
460 if let Ok(Some(path)) = super::fill_utf16_buf(
461 |buf, size| c::GetSystemDirectoryW(buf, size),
462 |buf| exists(PathBuf::from(OsString::from_wide(buf))),
466 #[cfg(not(target_vendor = "uwp"))]
468 if let Ok(Some(path)) = super::fill_utf16_buf(
469 |buf, size| c::GetWindowsDirectoryW(buf, size),
470 |buf| exists(PathBuf::from(OsString::from_wide(buf))),
478 if let Some(parent_paths) = parent_paths() {
479 for path in env::split_paths(&parent_paths).filter(|p| !p.as_os_str().is_empty()) {
480 if let Some(path) = exists(path) {
489 fn to_handle(&self, stdio_id: c::DWORD, pipe: &mut Option<AnonPipe>) -> io::Result<Handle> {
491 // If no stdio handle is available, then inherit means that it
492 // should still be unavailable so propagate the
493 // INVALID_HANDLE_VALUE.
494 Stdio::Inherit => match stdio::get_handle(stdio_id) {
496 let io = Handle::from_raw_handle(io);
497 let ret = io.duplicate(0, true, c::DUPLICATE_SAME_ACCESS);
498 io.into_raw_handle();
501 Err(..) => unsafe { Ok(Handle::from_raw_handle(c::INVALID_HANDLE_VALUE)) },
505 let ours_readable = stdio_id != c::STD_INPUT_HANDLE;
506 let pipes = pipe::anon_pipe(ours_readable, true)?;
507 *pipe = Some(pipes.ours);
508 Ok(pipes.theirs.into_handle())
511 Stdio::Handle(ref handle) => handle.duplicate(0, true, c::DUPLICATE_SAME_ACCESS),
513 // Open up a reference to NUL with appropriate read/write
514 // permissions as well as the ability to be inherited to child
515 // processes (as this is about to be inherited).
517 let size = mem::size_of::<c::SECURITY_ATTRIBUTES>();
518 let mut sa = c::SECURITY_ATTRIBUTES {
519 nLength: size as c::DWORD,
520 lpSecurityDescriptor: ptr::null_mut(),
523 let mut opts = OpenOptions::new();
524 opts.read(stdio_id == c::STD_INPUT_HANDLE);
525 opts.write(stdio_id != c::STD_INPUT_HANDLE);
526 opts.security_attributes(&mut sa);
527 File::open(Path::new("NUL"), &opts).map(|file| file.into_inner())
533 impl From<AnonPipe> for Stdio {
534 fn from(pipe: AnonPipe) -> Stdio {
535 Stdio::Handle(pipe.into_handle())
539 impl From<File> for Stdio {
540 fn from(file: File) -> Stdio {
541 Stdio::Handle(file.into_inner())
545 ////////////////////////////////////////////////////////////////////////////////
547 ////////////////////////////////////////////////////////////////////////////////
549 /// A value representing a child process.
551 /// The lifetime of this value is linked to the lifetime of the actual
552 /// process - the Process destructor calls self.finish() which waits
553 /// for the process to terminate.
559 pub fn kill(&mut self) -> io::Result<()> {
560 cvt(unsafe { c::TerminateProcess(self.handle.as_raw_handle(), 1) })?;
564 pub fn id(&self) -> u32 {
565 unsafe { c::GetProcessId(self.handle.as_raw_handle()) as u32 }
568 pub fn wait(&mut self) -> io::Result<ExitStatus> {
570 let res = c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE);
571 if res != c::WAIT_OBJECT_0 {
572 return Err(Error::last_os_error());
575 cvt(c::GetExitCodeProcess(self.handle.as_raw_handle(), &mut status))?;
576 Ok(ExitStatus(status))
580 pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
582 match c::WaitForSingleObject(self.handle.as_raw_handle(), 0) {
583 c::WAIT_OBJECT_0 => {}
587 _ => return Err(io::Error::last_os_error()),
590 cvt(c::GetExitCodeProcess(self.handle.as_raw_handle(), &mut status))?;
591 Ok(Some(ExitStatus(status)))
595 pub fn handle(&self) -> &Handle {
599 pub fn into_handle(self) -> Handle {
604 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
605 pub struct ExitStatus(c::DWORD);
608 pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
609 match NonZeroDWORD::try_from(self.0) {
610 /* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)),
611 /* was zero, couldn't convert */ Err(_) => Ok(()),
614 pub fn code(&self) -> Option<i32> {
619 /// Converts a raw `c::DWORD` to a type-safe `ExitStatus` by wrapping it without copying.
620 impl From<c::DWORD> for ExitStatus {
621 fn from(u: c::DWORD) -> ExitStatus {
626 impl fmt::Display for ExitStatus {
627 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
628 // Windows exit codes with the high bit set typically mean some form of
629 // unhandled exception or warning. In this scenario printing the exit
630 // code in decimal doesn't always make sense because it's a very large
631 // and somewhat gibberish number. The hex code is a bit more
632 // recognizable and easier to search for, so print that.
633 if self.0 & 0x80000000 != 0 {
634 write!(f, "exit code: {:#x}", self.0)
636 write!(f, "exit code: {}", self.0)
641 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
642 pub struct ExitStatusError(c::NonZeroDWORD);
644 impl Into<ExitStatus> for ExitStatusError {
645 fn into(self) -> ExitStatus {
646 ExitStatus(self.0.into())
650 impl ExitStatusError {
651 pub fn code(self) -> Option<NonZeroI32> {
652 Some((u32::from(self.0) as i32).try_into().unwrap())
656 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
657 pub struct ExitCode(c::DWORD);
660 pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
661 pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
664 pub fn as_i32(&self) -> i32 {
669 fn zeroed_startupinfo() -> c::STARTUPINFO {
672 lpReserved: ptr::null_mut(),
673 lpDesktop: ptr::null_mut(),
674 lpTitle: ptr::null_mut(),
685 lpReserved2: ptr::null_mut(),
686 hStdInput: c::INVALID_HANDLE_VALUE,
687 hStdOutput: c::INVALID_HANDLE_VALUE,
688 hStdError: c::INVALID_HANDLE_VALUE,
692 fn zeroed_process_information() -> c::PROCESS_INFORMATION {
693 c::PROCESS_INFORMATION {
694 hProcess: ptr::null_mut(),
695 hThread: ptr::null_mut(),
702 // Every arg is quoted
704 // Whitespace and empty args are quoted
706 // Arg appended without any changes (#29494)
710 // Produces a wide string *without terminating null*; returns an error if
711 // `prog` or any of the `args` contain a nul.
712 fn make_command_line(prog: &OsStr, args: &[Arg], force_quotes: bool) -> io::Result<Vec<u16>> {
713 // Encode the command and arguments in a command line string such
714 // that the spawned process may recover them using CommandLineToArgvW.
715 let mut cmd: Vec<u16> = Vec::new();
717 // CreateFileW has special handling for .bat and .cmd files, which means we
718 // need to add an extra pair of quotes surrounding the whole command line
719 // so they are properly passed on to the script.
721 let is_batch_file = Path::new(prog)
723 .map(|ext| ext.eq_ignore_ascii_case("cmd") || ext.eq_ignore_ascii_case("bat"))
726 cmd.push(b'"' as u16);
729 // Always quote the program name so CreateProcess doesn't interpret args as
730 // part of the name if the binary wasn't found first time.
731 append_arg(&mut cmd, prog, Quote::Always)?;
733 cmd.push(' ' as u16);
734 let (arg, quote) = match arg {
735 Arg::Regular(arg) => (arg, if force_quotes { Quote::Always } else { Quote::Auto }),
736 Arg::Raw(arg) => (arg, Quote::Never),
738 append_arg(&mut cmd, arg, quote)?;
741 cmd.push(b'"' as u16);
745 fn append_arg(cmd: &mut Vec<u16>, arg: &OsStr, quote: Quote) -> io::Result<()> {
746 // If an argument has 0 characters then we need to quote it to ensure
747 // that it actually gets passed through on the command line or otherwise
748 // it will be dropped entirely when parsed on the other end.
749 ensure_no_nuls(arg)?;
750 let arg_bytes = &arg.as_inner().inner.as_inner();
751 let (quote, escape) = match quote {
752 Quote::Always => (true, true),
754 (arg_bytes.iter().any(|c| *c == b' ' || *c == b'\t') || arg_bytes.is_empty(), true)
756 Quote::Never => (false, false),
759 cmd.push('"' as u16);
762 let mut backslashes: usize = 0;
763 for x in arg.encode_wide() {
765 if x == '\\' as u16 {
769 // Add n+1 backslashes to total 2n+1 before internal '"'.
770 cmd.extend((0..=backslashes).map(|_| '\\' as u16));
779 // Add n backslashes to total 2n before ending '"'.
780 cmd.extend((0..backslashes).map(|_| '\\' as u16));
781 cmd.push('"' as u16);
787 fn make_envp(maybe_env: Option<BTreeMap<EnvKey, OsString>>) -> io::Result<(*mut c_void, Vec<u16>)> {
788 // On Windows we pass an "environment block" which is not a char**, but
789 // rather a concatenation of null-terminated k=v\0 sequences, with a final
791 if let Some(env) = maybe_env {
792 let mut blk = Vec::new();
794 // If there are no environment variables to set then signal this by
801 ensure_no_nuls(k.os_string)?;
803 blk.push('=' as u16);
804 blk.extend(ensure_no_nuls(v)?.encode_wide());
808 Ok((blk.as_mut_ptr() as *mut c_void, blk))
810 Ok((ptr::null_mut(), Vec::new()))
814 fn make_dirp(d: Option<&OsString>) -> io::Result<(*const u16, Vec<u16>)> {
817 let mut dir_str: Vec<u16> = ensure_no_nuls(dir)?.encode_wide().collect();
819 Ok((dir_str.as_ptr(), dir_str))
821 None => Ok((ptr::null(), Vec::new())),
825 pub struct CommandArgs<'a> {
826 iter: crate::slice::Iter<'a, Arg>,
829 impl<'a> Iterator for CommandArgs<'a> {
830 type Item = &'a OsStr;
831 fn next(&mut self) -> Option<&'a OsStr> {
832 self.iter.next().map(|arg| match arg {
833 Arg::Regular(s) | Arg::Raw(s) => s.as_ref(),
836 fn size_hint(&self) -> (usize, Option<usize>) {
837 self.iter.size_hint()
841 impl<'a> ExactSizeIterator for CommandArgs<'a> {
842 fn len(&self) -> usize {
845 fn is_empty(&self) -> bool {
850 impl<'a> fmt::Debug for CommandArgs<'a> {
851 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
852 f.debug_list().entries(self.iter.clone()).finish()