1 //! Unix-specific extensions to primitives in the [`std::process`] module.
3 //! [`std::process`]: crate::process
5 #![stable(feature = "rust1", since = "1.0.0")]
9 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
11 use crate::sealed::Sealed;
13 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
15 /// Unix-specific extensions to the [`process::Command`] builder.
17 /// This trait is sealed: it cannot be implemented outside the standard library.
18 /// This is so that future additional methods are not breaking changes.
19 #[stable(feature = "rust1", since = "1.0.0")]
20 pub trait CommandExt: Sealed {
21 /// Sets the child process's user ID. This translates to a
22 /// `setuid` call in the child process. Failure in the `setuid`
23 /// call will cause the spawn to fail.
24 #[stable(feature = "rust1", since = "1.0.0")]
27 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] id: u32,
28 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] id: u16,
29 ) -> &mut process::Command;
31 /// Similar to `uid`, but sets the group ID of the child process. This has
32 /// the same semantics as the `uid` field.
33 #[stable(feature = "rust1", since = "1.0.0")]
36 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] id: u32,
37 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] id: u16,
38 ) -> &mut process::Command;
40 /// Sets the supplementary group IDs for the calling process. Translates to
41 /// a `setgroups` call in the child process.
42 #[unstable(feature = "setgroups", issue = "90747")]
45 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] groups: &[u32],
46 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] groups: &[u16],
47 ) -> &mut process::Command;
49 /// Schedules a closure to be run just before the `exec` function is
52 /// The closure is allowed to return an I/O error whose OS error code will
53 /// be communicated back to the parent and returned as an error from when
54 /// the spawn was requested.
56 /// Multiple closures can be registered and they will be called in order of
57 /// their registration. If a closure returns `Err` then no further closures
58 /// will be called and the spawn operation will immediately return with a
61 /// # Notes and Safety
63 /// This closure will be run in the context of the child process after a
64 /// `fork`. This primarily means that any modifications made to memory on
65 /// behalf of this closure will **not** be visible to the parent process.
66 /// This is often a very constrained environment where normal operations
67 /// like `malloc`, accessing environment variables through [`std::env`]
68 /// or acquiring a mutex are not guaranteed to work (due to
69 /// other threads perhaps still running when the `fork` was run).
71 /// For further details refer to the [POSIX fork() specification]
72 /// and the equivalent documentation for any targeted
73 /// platform, especially the requirements around *async-signal-safety*.
75 /// This also means that all resources such as file descriptors and
76 /// memory-mapped regions got duplicated. It is your responsibility to make
77 /// sure that the closure does not violate library invariants by making
78 /// invalid use of these duplicates.
80 /// Panicking in the closure is safe only if all the format arguments for the
81 /// panic message can be safely formatted; this is because although
82 /// `Command` calls [`std::panic::always_abort`](crate::panic::always_abort)
83 /// before calling the pre_exec hook, panic will still try to format the
86 /// When this closure is run, aspects such as the stdio file descriptors and
87 /// working directory have successfully been changed, so output to these
88 /// locations might not appear where intended.
90 /// [POSIX fork() specification]:
91 /// https://pubs.opengroup.org/onlinepubs/9699919799/functions/fork.html
92 /// [`std::env`]: mod@crate::env
93 #[stable(feature = "process_pre_exec", since = "1.34.0")]
94 unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
96 F: FnMut() -> io::Result<()> + Send + Sync + 'static;
98 /// Schedules a closure to be run just before the `exec` function is
101 /// This method is stable and usable, but it should be unsafe. To fix
102 /// that, it got deprecated in favor of the unsafe [`pre_exec`].
104 /// [`pre_exec`]: CommandExt::pre_exec
105 #[stable(feature = "process_exec", since = "1.15.0")]
106 #[rustc_deprecated(since = "1.37.0", reason = "should be unsafe, use `pre_exec` instead")]
107 fn before_exec<F>(&mut self, f: F) -> &mut process::Command
109 F: FnMut() -> io::Result<()> + Send + Sync + 'static,
111 unsafe { self.pre_exec(f) }
114 /// Performs all the required setup by this `Command`, followed by calling
115 /// the `execvp` syscall.
117 /// On success this function will not return, and otherwise it will return
118 /// an error indicating why the exec (or another part of the setup of the
119 /// `Command`) failed.
121 /// `exec` not returning has the same implications as calling
122 /// [`process::exit`] – no destructors on the current stack or any other
123 /// thread’s stack will be run. Therefore, it is recommended to only call
124 /// `exec` at a point where it is fine to not run any destructors. Note,
125 /// that the `execvp` syscall independently guarantees that all memory is
126 /// freed and all file descriptors with the `CLOEXEC` option (set by default
127 /// on all file descriptors opened by the standard library) are closed.
129 /// This function, unlike `spawn`, will **not** `fork` the process to create
130 /// a new child. Like spawn, however, the default behavior for the stdio
131 /// descriptors will be to inherited from the current process.
135 /// The process may be in a "broken state" if this function returns in
136 /// error. For example the working directory, environment variables, signal
137 /// handling settings, various user/group information, or aspects of stdio
138 /// file descriptors may have changed. If a "transactional spawn" is
139 /// required to gracefully handle errors it is recommended to use the
140 /// cross-platform `spawn` instead.
141 #[stable(feature = "process_exec2", since = "1.9.0")]
142 fn exec(&mut self) -> io::Error;
144 /// Set executable argument
146 /// Set the first process argument, `argv[0]`, to something other than the
147 /// default executable path.
148 #[stable(feature = "process_set_argv0", since = "1.45.0")]
149 fn arg0<S>(&mut self, arg: S) -> &mut process::Command
153 /// Sets the process group ID of the child process. Translates to a `setpgid` call in the child
155 #[unstable(feature = "process_set_process_group", issue = "93857")]
156 fn process_group(&mut self, pgroup: i32) -> &mut process::Command;
159 #[stable(feature = "rust1", since = "1.0.0")]
160 impl CommandExt for process::Command {
163 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] id: u32,
164 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] id: u16,
165 ) -> &mut process::Command {
166 self.as_inner_mut().uid(id);
172 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] id: u32,
173 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] id: u16,
174 ) -> &mut process::Command {
175 self.as_inner_mut().gid(id);
181 #[cfg(not(any(target_os = "vxworks", target_os = "espidf")))] groups: &[u32],
182 #[cfg(any(target_os = "vxworks", target_os = "espidf"))] groups: &[u16],
183 ) -> &mut process::Command {
184 self.as_inner_mut().groups(groups);
188 unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
190 F: FnMut() -> io::Result<()> + Send + Sync + 'static,
192 self.as_inner_mut().pre_exec(Box::new(f));
196 fn exec(&mut self) -> io::Error {
197 // NOTE: This may *not* be safe to call after `libc::fork`, because it
198 // may allocate. That may be worth fixing at some point in the future.
199 self.as_inner_mut().exec(sys::process::Stdio::Inherit)
202 fn arg0<S>(&mut self, arg: S) -> &mut process::Command
206 self.as_inner_mut().set_arg_0(arg.as_ref());
210 fn process_group(&mut self, pgroup: i32) -> &mut process::Command {
211 self.as_inner_mut().pgroup(pgroup);
216 /// Unix-specific extensions to [`process::ExitStatus`] and
217 /// [`ExitStatusError`](process::ExitStatusError).
219 /// On Unix, `ExitStatus` **does not necessarily represent an exit status**, as
220 /// passed to the `_exit` system call or returned by
221 /// [`ExitStatus::code()`](crate::process::ExitStatus::code). It represents **any wait status**
222 /// as returned by one of the `wait` family of system
225 /// A Unix wait status (a Rust `ExitStatus`) can represent a Unix exit status, but can also
226 /// represent other kinds of process event.
228 /// This trait is sealed: it cannot be implemented outside the standard library.
229 /// This is so that future additional methods are not breaking changes.
230 #[stable(feature = "rust1", since = "1.0.0")]
231 pub trait ExitStatusExt: Sealed {
232 /// Creates a new `ExitStatus` or `ExitStatusError` from the raw underlying integer status
233 /// value from `wait`
235 /// The value should be a **wait status, not an exit status**.
239 /// Panics on an attempt to make an `ExitStatusError` from a wait status of `0`.
241 /// Making an `ExitStatus` always succeeds and never panics.
242 #[stable(feature = "exit_status_from", since = "1.12.0")]
243 fn from_raw(raw: i32) -> Self;
245 /// If the process was terminated by a signal, returns that signal.
247 /// In other words, if `WIFSIGNALED`, this returns `WTERMSIG`.
248 #[stable(feature = "rust1", since = "1.0.0")]
249 fn signal(&self) -> Option<i32>;
251 /// If the process was terminated by a signal, says whether it dumped core.
252 #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
253 fn core_dumped(&self) -> bool;
255 /// If the process was stopped by a signal, returns that signal.
257 /// In other words, if `WIFSTOPPED`, this returns `WSTOPSIG`. This is only possible if the status came from
258 /// a `wait` system call which was passed `WUNTRACED`, and was then converted into an `ExitStatus`.
259 #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
260 fn stopped_signal(&self) -> Option<i32>;
262 /// Whether the process was continued from a stopped status.
264 /// Ie, `WIFCONTINUED`. This is only possible if the status came from a `wait` system call
265 /// which was passed `WCONTINUED`, and was then converted into an `ExitStatus`.
266 #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
267 fn continued(&self) -> bool;
269 /// Returns the underlying raw `wait` status.
271 /// The returned integer is a **wait status, not an exit status**.
272 #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
273 fn into_raw(self) -> i32;
276 #[stable(feature = "rust1", since = "1.0.0")]
277 impl ExitStatusExt for process::ExitStatus {
278 fn from_raw(raw: i32) -> Self {
279 process::ExitStatus::from_inner(From::from(raw))
282 fn signal(&self) -> Option<i32> {
283 self.as_inner().signal()
286 fn core_dumped(&self) -> bool {
287 self.as_inner().core_dumped()
290 fn stopped_signal(&self) -> Option<i32> {
291 self.as_inner().stopped_signal()
294 fn continued(&self) -> bool {
295 self.as_inner().continued()
298 fn into_raw(self) -> i32 {
299 self.as_inner().into_raw().into()
303 #[unstable(feature = "exit_status_error", issue = "84908")]
304 impl ExitStatusExt for process::ExitStatusError {
305 fn from_raw(raw: i32) -> Self {
306 process::ExitStatus::from_raw(raw)
308 .expect_err("<ExitStatusError as ExitStatusExt>::from_raw(0) but zero is not an error")
311 fn signal(&self) -> Option<i32> {
312 self.into_status().signal()
315 fn core_dumped(&self) -> bool {
316 self.into_status().core_dumped()
319 fn stopped_signal(&self) -> Option<i32> {
320 self.into_status().stopped_signal()
323 fn continued(&self) -> bool {
324 self.into_status().continued()
327 fn into_raw(self) -> i32 {
328 self.into_status().into_raw()
332 #[stable(feature = "process_extensions", since = "1.2.0")]
333 impl FromRawFd for process::Stdio {
335 unsafe fn from_raw_fd(fd: RawFd) -> process::Stdio {
336 let fd = sys::fd::FileDesc::from_raw_fd(fd);
337 let io = sys::process::Stdio::Fd(fd);
338 process::Stdio::from_inner(io)
342 #[unstable(feature = "io_safety", issue = "87074")]
343 impl From<OwnedFd> for process::Stdio {
345 fn from(fd: OwnedFd) -> process::Stdio {
346 let fd = sys::fd::FileDesc::from_inner(fd);
347 let io = sys::process::Stdio::Fd(fd);
348 process::Stdio::from_inner(io)
352 #[stable(feature = "process_extensions", since = "1.2.0")]
353 impl AsRawFd for process::ChildStdin {
355 fn as_raw_fd(&self) -> RawFd {
356 self.as_inner().as_raw_fd()
360 #[stable(feature = "process_extensions", since = "1.2.0")]
361 impl AsRawFd for process::ChildStdout {
363 fn as_raw_fd(&self) -> RawFd {
364 self.as_inner().as_raw_fd()
368 #[stable(feature = "process_extensions", since = "1.2.0")]
369 impl AsRawFd for process::ChildStderr {
371 fn as_raw_fd(&self) -> RawFd {
372 self.as_inner().as_raw_fd()
376 #[stable(feature = "into_raw_os", since = "1.4.0")]
377 impl IntoRawFd for process::ChildStdin {
379 fn into_raw_fd(self) -> RawFd {
380 self.into_inner().into_inner().into_raw_fd()
384 #[stable(feature = "into_raw_os", since = "1.4.0")]
385 impl IntoRawFd for process::ChildStdout {
387 fn into_raw_fd(self) -> RawFd {
388 self.into_inner().into_inner().into_raw_fd()
392 #[stable(feature = "into_raw_os", since = "1.4.0")]
393 impl IntoRawFd for process::ChildStderr {
395 fn into_raw_fd(self) -> RawFd {
396 self.into_inner().into_inner().into_raw_fd()
400 #[unstable(feature = "io_safety", issue = "87074")]
401 impl AsFd for crate::process::ChildStdin {
403 fn as_fd(&self) -> BorrowedFd<'_> {
404 self.as_inner().as_fd()
408 #[unstable(feature = "io_safety", issue = "87074")]
409 impl From<crate::process::ChildStdin> for OwnedFd {
411 fn from(child_stdin: crate::process::ChildStdin) -> OwnedFd {
412 child_stdin.into_inner().into_inner().into_inner()
416 #[unstable(feature = "io_safety", issue = "87074")]
417 impl AsFd for crate::process::ChildStdout {
419 fn as_fd(&self) -> BorrowedFd<'_> {
420 self.as_inner().as_fd()
424 #[unstable(feature = "io_safety", issue = "87074")]
425 impl From<crate::process::ChildStdout> for OwnedFd {
427 fn from(child_stdout: crate::process::ChildStdout) -> OwnedFd {
428 child_stdout.into_inner().into_inner().into_inner()
432 #[unstable(feature = "io_safety", issue = "87074")]
433 impl AsFd for crate::process::ChildStderr {
435 fn as_fd(&self) -> BorrowedFd<'_> {
436 self.as_inner().as_fd()
440 #[unstable(feature = "io_safety", issue = "87074")]
441 impl From<crate::process::ChildStderr> for OwnedFd {
443 fn from(child_stderr: crate::process::ChildStderr) -> OwnedFd {
444 child_stderr.into_inner().into_inner().into_inner()
448 /// Returns the OS-assigned process identifier associated with this process's parent.
450 #[stable(feature = "unix_ppid", since = "1.27.0")]
451 pub fn parent_id() -> u32 {
452 crate::sys::os::getppid()