unix.rs - source (original) (raw)
std/sys/process/unix/
unix.rs
1#[cfg(target_os = "vxworks")]
2use libc::RTP_ID as pid_t;
3#[cfg(not(target_os = "vxworks"))]
4use libc::{c_int, pid_t};
5#[cfg(not(any(
6 target_os = "vxworks",
7 target_os = "l4re",
8 target_os = "tvos",
9 target_os = "watchos",
10)))]
11use libc::{gid_t, uid_t};
12
13use super::common::*;
14use crate::io::{self, Error, ErrorKind};
15use crate::num::NonZero;
16use crate::sys::cvt;
17#[cfg(target_os = "linux")]
18use crate::sys::pal::linux::pidfd::PidFd;
19use crate::{fmt, mem, sys};
20
21cfg_if::cfg_if! {
22 if #[cfg(target_os = "nto")] {
23 use crate::thread;
24 use libc::{c_char, posix_spawn_file_actions_t, posix_spawnattr_t};
25 use crate::time::Duration;
26 use crate::sync::LazyLock;
27 // Get smallest amount of time we can sleep.
28 // Return a common value if it cannot be determined.
29 fn get_clock_resolution() -> Duration {
30 static MIN_DELAY: LazyLock<Duration, fn() -> Duration> = LazyLock::new(|| {
31 let mut mindelay = libc::timespec { tv_sec: 0, tv_nsec: 0 };
32 if unsafe { libc::clock_getres(libc::CLOCK_MONOTONIC, &mut mindelay) } == 0
33 {
34 Duration::from_nanos(mindelay.tv_nsec as u64)
35 } else {
36 Duration::from_millis(1)
37 }
38 });
39 *MIN_DELAY
40 }
41 // Arbitrary minimum sleep duration for retrying fork/spawn
42 const MIN_FORKSPAWN_SLEEP: Duration = Duration::from_nanos(1);
43 // Maximum duration of sleeping before giving up and returning an error
44 const MAX_FORKSPAWN_SLEEP: Duration = Duration::from_millis(1000);
45 }
46}
47
48////////////////////////////////////////////////////////////////////////////////
49// Command
50////////////////////////////////////////////////////////////////////////////////
51
52impl Command {
53 pub fn spawn(
54 &mut self,
55 default: Stdio,
56 needs_stdin: bool,
57 ) -> io::Result<(Process, StdioPipes)> {
58 const CLOEXEC_MSG_FOOTER: [u8; 4] = *b"NOEX";
59
60 let envp = self.capture_env();
61
62 if self.saw_nul() {
63 return Err(io::const_error!(
64 ErrorKind::InvalidInput,
65 "nul byte found in provided data",
66 ));
67 }
68
69 let (ours, theirs) = self.setup_io(default, needs_stdin)?;
70
71 if let Some(ret) = self.posix_spawn(&theirs, envp.as_ref())? {
72 return Ok((ret, ours));
73 }
74
75 #[cfg(target_os = "linux")]
76 let (input, output) = sys:🥅:Socket::new_pair(libc::AF_UNIX, libc::SOCK_SEQPACKET)?;
77
78 #[cfg(not(target_os = "linux"))]
79 let (input, output) = sys::pipe::anon_pipe()?;
80
81 // Whatever happens after the fork is almost for sure going to touch or
82 // look at the environment in one way or another (PATH in `execvp` or
83 // accessing the `environ` pointer ourselves). Make sure no other thread
84 // is accessing the environment when we do the fork itself.
85 //
86 // Note that as soon as we're done with the fork there's no need to hold
87 // a lock any more because the parent won't do anything and the child is
88 // in its own process. Thus the parent drops the lock guard immediately.
89 // The child calls `mem::forget` to leak the lock, which is crucial because
90 // releasing a lock is not async-signal-safe.
91 let env_lock = sys::env::env_read_lock();
92 let pid = unsafe { self.do_fork()? };
93
94 if pid == 0 {
95 crate::panic::always_abort();
96 mem::forget(env_lock); // avoid non-async-signal-safe unlocking
97 drop(input);
98 #[cfg(target_os = "linux")]
99 if self.get_create_pidfd() {
100 self.send_pidfd(&output);
101 }
102 let Err(err) = unsafe { self.do_exec(theirs, envp.as_ref()) };
103 let errno = err.raw_os_error().unwrap_or(libc::EINVAL) as u32;
104 let errno = errno.to_be_bytes();
105 let bytes = [
106 errno[0],
107 errno[1],
108 errno[2],
109 errno[3],
110 CLOEXEC_MSG_FOOTER[0],
111 CLOEXEC_MSG_FOOTER[1],
112 CLOEXEC_MSG_FOOTER[2],
113 CLOEXEC_MSG_FOOTER[3],
114 ];
115 // pipe I/O up to PIPE_BUF bytes should be atomic, and then
116 // we want to be sure we *don't* run at_exit destructors as
117 // we're being torn down regardless
118 rtassert!(output.write(&bytes).is_ok());
119 unsafe { libc::_exit(1) }
120 }
121
122 drop(env_lock);
123 drop(output);
124
125 #[cfg(target_os = "linux")]
126 let pidfd = if self.get_create_pidfd() { self.recv_pidfd(&input) } else { -1 };
127
128 #[cfg(not(target_os = "linux"))]
129 let pidfd = -1;
130
131 // Safety: We obtained the pidfd (on Linux) using SOCK_SEQPACKET, so it's valid.
132 let mut p = unsafe { Process::new(pid, pidfd) };
133 let mut bytes = [0; 8];
134
135 // loop to handle EINTR
136 loop {
137 match input.read(&mut bytes) {
138 Ok(0) => return Ok((p, ours)),
139 Ok(8) => {
140 let (errno, footer) = bytes.split_at(4);
141 assert_eq!(
142 CLOEXEC_MSG_FOOTER, footer,
143 "Validation on the CLOEXEC pipe failed: {:?}",
144 bytes
145 );
146 let errno = i32::from_be_bytes(errno.try_into().unwrap());
147 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
148 return Err(Error::from_raw_os_error(errno));
149 }
150 Err(ref e) if e.is_interrupted() => {}
151 Err(e) => {
152 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
153 panic!("the CLOEXEC pipe failed: {e:?}")
154 }
155 Ok(..) => {
156 // pipe I/O up to PIPE_BUF bytes should be atomic
157 // similarly SOCK_SEQPACKET messages should arrive whole
158 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
159 panic!("short read on the CLOEXEC pipe")
160 }
161 }
162 }
163 }
164
165 // WatchOS and TVOSÂ headers mark the `fork`/`exec*` functions with
166 // `__WATCHOS_PROHIBITED __TVOS_PROHIBITED`, and indicate that the
167 // `posix_spawn*` functions should be used instead. It isn't entirely clear
168 // what `PROHIBITED` means here (e.g. if calls to these functions are
169 // allowed to exist in dead code), but it sounds bad, so we go out of our
170 // way to avoid that all-together.
171 #[cfg(any(target_os = "tvos", target_os = "watchos"))]
172 const ERR_APPLE_TV_WATCH_NO_FORK_EXEC: Error = io::const_error!(
173 ErrorKind::Unsupported,
174 "`fork`+`exec`-based process spawning is not supported on this target",
175 );
176
177 #[cfg(any(target_os = "tvos", target_os = "watchos"))]
178 unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
179 return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
180 }
181
182 // Attempts to fork the process. If successful, returns Ok((0, -1))
183 // in the child, and Ok((child_pid, -1)) in the parent.
184 #[cfg(not(any(target_os = "watchos", target_os = "tvos", target_os = "nto")))]
185 unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
186 cvt(libc::fork())
187 }
188
189 // On QNX Neutrino, fork can fail with EBADF in case "another thread might have opened
190 // or closed a file descriptor while the fork() was occurring".
191 // Documentation says "... or try calling fork() again". This is what we do here.
192 // See also https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/f/fork.html
193 #[cfg(target_os = "nto")]
194 unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
195 use crate::sys::os::errno;
196
197 let mut delay = MIN_FORKSPAWN_SLEEP;
198
199 loop {
200 let r = libc::fork();
201 if r == -1 as libc::pid_t && errno() as libc::c_int == libc::EBADF {
202 if delay < get_clock_resolution() {
203 // We cannot sleep this short (it would be longer).
204 // Yield instead.
205 thread::yield_now();
206 } else if delay < MAX_FORKSPAWN_SLEEP {
207 thread::sleep(delay);
208 } else {
209 return Err(io::const_error!(
210 ErrorKind::WouldBlock,
211 "forking returned EBADF too often",
212 ));
213 }
214 delay *= 2;
215 continue;
216 } else {
217 return cvt(r);
218 }
219 }
220 }
221
222 pub fn exec(&mut self, default: Stdio) -> io::Error {
223 let envp = self.capture_env();
224
225 if self.saw_nul() {
226 return io::const_error!(ErrorKind::InvalidInput, "nul byte found in provided data");
227 }
228
229 match self.setup_io(default, true) {
230 Ok((_, theirs)) => {
231 unsafe {
232 // Similar to when forking, we want to ensure that access to
233 // the environment is synchronized, so make sure to grab the
234 // environment lock before we try to exec.
235 let _lock = sys::env::env_read_lock();
236
237 let Err(e) = self.do_exec(theirs, envp.as_ref());
238 e
239 }
240 }
241 Err(e) => e,
242 }
243 }
244
245 // And at this point we've reached a special time in the life of the
246 // child. The child must now be considered hamstrung and unable to
247 // do anything other than syscalls really. Consider the following
248 // scenario:
249 //
250 // 1. Thread A of process 1 grabs the malloc() mutex
251 // 2. Thread B of process 1 forks(), creating thread C
252 // 3. Thread C of process 2 then attempts to malloc()
253 // 4. The memory of process 2 is the same as the memory of
254 // process 1, so the mutex is locked.
255 //
256 // This situation looks a lot like deadlock, right? It turns out
257 // that this is what pthread_atfork() takes care of, which is
258 // presumably implemented across platforms. The first thing that
259 // threads to *before* forking is to do things like grab the malloc
260 // mutex, and then after the fork they unlock it.
261 //
262 // Despite this information, libnative's spawn has been witnessed to
263 // deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
264 // all collected backtraces point at malloc/free traffic in the
265 // child spawned process.
266 //
267 // For this reason, the block of code below should contain 0
268 // invocations of either malloc of free (or their related friends).
269 //
270 // As an example of not having malloc/free traffic, we don't close
271 // this file descriptor by dropping the FileDesc (which contains an
272 // allocation). Instead we just close it manually. This will never
273 // have the drop glue anyway because this code never returns (the
274 // child will either exec() or invoke libc::exit)
275 #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
276 unsafe fn do_exec(
277 &mut self,
278 stdio: ChildPipes,
279 maybe_envp: Option<&CStringArray>,
280 ) -> Result<!, io::Error> {
281 use crate::sys::{self, cvt_r};
282
283 if let Some(fd) = stdio.stdin.fd() {
284 cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
285 }
286 if let Some(fd) = stdio.stdout.fd() {
287 cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
288 }
289 if let Some(fd) = stdio.stderr.fd() {
290 cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
291 }
292
293 #[cfg(not(target_os = "l4re"))]
294 {
295 if let Some(_g) = self.get_groups() {
296 //FIXME: Redox kernel does not support setgroups yet
297 #[cfg(not(target_os = "redox"))]
298 cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
299 }
300 if let Some(u) = self.get_gid() {
301 cvt(libc::setgid(u as gid_t))?;
302 }
303 if let Some(u) = self.get_uid() {
304 // When dropping privileges from root, the `setgroups` call
305 // will remove any extraneous groups. We only drop groups
306 // if we have CAP_SETGID and we weren't given an explicit
307 // set of groups. If we don't call this, then even though our
308 // uid has dropped, we may still have groups that enable us to
309 // do super-user things.
310 //FIXME: Redox kernel does not support setgroups yet
311 #[cfg(not(target_os = "redox"))]
312 if self.get_groups().is_none() {
313 let res = cvt(libc::setgroups(0, crate::ptr::null()));
314 if let Err(e) = res {
315 // Here we ignore the case of not having CAP_SETGID.
316 // An alternative would be to require CAP_SETGID (in
317 // addition to CAP_SETUID) for setting the UID.
318 if e.raw_os_error() != Some(libc::EPERM) {
319 return Err(e.into());
320 }
321 }
322 }
323 cvt(libc::setuid(u as uid_t))?;
324 }
325 }
326 if let Some(cwd) = self.get_cwd() {
327 cvt(libc::chdir(cwd.as_ptr()))?;
328 }
329
330 if let Some(pgroup) = self.get_pgroup() {
331 cvt(libc::setpgid(0, pgroup))?;
332 }
333
334 // emscripten has no signal support.
335 #[cfg(not(target_os = "emscripten"))]
336 {
337 // Inherit the signal mask from the parent rather than resetting it (i.e. do not call
338 // pthread_sigmask).
339
340 // If -Zon-broken-pipe is used, don't reset SIGPIPE to SIG_DFL.
341 // If -Zon-broken-pipe is not used, reset SIGPIPE to SIG_DFL for backward compatibility.
342 //
343 // -Zon-broken-pipe is an opportunity to change the default here.
344 if !crate::sys::pal::on_broken_pipe_flag_used() {
345 #[cfg(target_os = "android")] // see issue #88585
346 {
347 let mut action: libc::sigaction = mem::zeroed();
348 action.sa_sigaction = libc::SIG_DFL;
349 cvt(libc::sigaction(libc::SIGPIPE, &action, crate::ptr::null_mut()))?;
350 }
351 #[cfg(not(target_os = "android"))]
352 {
353 let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL);
354 if ret == libc::SIG_ERR {
355 return Err(io::Error::last_os_error());
356 }
357 }
358 #[cfg(target_os = "hurd")]
359 {
360 let ret = sys::signal(libc::SIGLOST, libc::SIG_DFL);
361 if ret == libc::SIG_ERR {
362 return Err(io::Error::last_os_error());
363 }
364 }
365 }
366 }
367
368 for callback in self.get_closures().iter_mut() {
369 callback()?;
370 }
371
372 // Although we're performing an exec here we may also return with an
373 // error from this function (without actually exec'ing) in which case we
374 // want to be sure to restore the global environment back to what it
375 // once was, ensuring that our temporary override, when free'd, doesn't
376 // corrupt our process's environment.
377 let mut _reset = None;
378 if let Some(envp) = maybe_envp {
379 struct Reset(*const *const libc::c_char);
380
381 impl Drop for Reset {
382 fn drop(&mut self) {
383 unsafe {
384 *sys::env::environ() = self.0;
385 }
386 }
387 }
388
389 _reset = Some(Reset(*sys::env::environ()));
390 *sys::env::environ() = envp.as_ptr();
391 }
392
393 libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr());
394 Err(io::Error::last_os_error())
395 }
396
397 #[cfg(any(target_os = "tvos", target_os = "watchos"))]
398 unsafe fn do_exec(
399 &mut self,
400 _stdio: ChildPipes,
401 _maybe_envp: Option<&CStringArray>,
402 ) -> Result<!, io::Error> {
403 return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
404 }
405
406 #[cfg(not(any(
407 target_os = "freebsd",
408 target_os = "illumos",
409 all(target_os = "linux", target_env = "gnu"),
410 all(target_os = "linux", target_env = "musl"),
411 target_os = "nto",
412 target_vendor = "apple",
413 target_os = "cygwin",
414 )))]
415 fn posix_spawn(
416 &mut self,
417 _: &ChildPipes,
418 _: Option<&CStringArray>,
419 ) -> io::Result<Option<Process>> {
420 Ok(None)
421 }
422
423 // Only support platforms for which posix_spawn() can return ENOENT
424 // directly.
425 #[cfg(any(
426 target_os = "freebsd",
427 target_os = "illumos",
428 all(target_os = "linux", target_env = "gnu"),
429 all(target_os = "linux", target_env = "musl"),
430 target_os = "nto",
431 target_vendor = "apple",
432 target_os = "cygwin",
433 ))]
434 fn posix_spawn(
435 &mut self,
436 stdio: &ChildPipes,
437 envp: Option<&CStringArray>,
438 ) -> io::Result<Option<Process>> {
439 #[cfg(target_os = "linux")]
440 use core::sync::atomic::{Atomic, AtomicU8, Ordering};
441
442 use crate::mem::MaybeUninit;
443 use crate::sys::{self, cvt_nz, on_broken_pipe_flag_used};
444
445 if self.get_gid().is_some()
446 || self.get_uid().is_some()
447 || (self.env_saw_path() && !self.program_is_path())
448 || !self.get_closures().is_empty()
449 || self.get_groups().is_some()
450 {
451 return Ok(None);
452 }
453
454 cfg_if::cfg_if! {
455 if #[cfg(target_os = "linux")] {
456 use crate::sys::weak::weak;
457
458 weak!(
459 fn pidfd_spawnp(
460 pidfd: *mut libc::c_int,
461 path: *const libc::c_char,
462 file_actions: *const libc::posix_spawn_file_actions_t,
463 attrp: *const libc::posix_spawnattr_t,
464 argv: *const *mut libc::c_char,
465 envp: *const *mut libc::c_char,
466 ) -> libc::c_int;
467 );
468
469 weak!(
470 fn pidfd_getpid(pidfd: libc::c_int) -> libc::c_int;
471 );
472
473 static PIDFD_SUPPORTED: Atomic<u8> = AtomicU8::new(0);
474 const UNKNOWN: u8 = 0;
475 const SPAWN: u8 = 1;
476 // Obtaining a pidfd via the fork+exec path might work
477 const FORK_EXEC: u8 = 2;
478 // Neither pidfd_spawn nor fork/exec will get us a pidfd.
479 // Instead we'll just posix_spawn if the other preconditions are met.
480 const NO: u8 = 3;
481
482 if self.get_create_pidfd() {
483 let mut support = PIDFD_SUPPORTED.load(Ordering::Relaxed);
484 if support == FORK_EXEC {
485 return Ok(None);
486 }
487 if support == UNKNOWN {
488 support = NO;
489 let our_pid = crate::process::id();
490 let pidfd = cvt(unsafe { libc::syscall(libc::SYS_pidfd_open, our_pid, 0) } as c_int);
491 match pidfd {
492 Ok(pidfd) => {
493 support = FORK_EXEC;
494 if let Some(Ok(pid)) = pidfd_getpid.get().map(|f| cvt(unsafe { f(pidfd) } as i32)) {
495 if pidfd_spawnp.get().is_some() && pid as u32 == our_pid {
496 support = SPAWN
497 }
498 }
499 unsafe { libc::close(pidfd) };
500 }
501 Err(e) if e.raw_os_error() == Some(libc::EMFILE) => {
502 // We're temporarily(?) out of file descriptors. In this case obtaining a pidfd would also fail
503 // Don't update the support flag so we can probe again later.
504 return Err(e)
505 }
506 _ => {}
507 }
508 PIDFD_SUPPORTED.store(support, Ordering::Relaxed);
509 if support == FORK_EXEC {
510 return Ok(None);
511 }
512 }
513 core::assert_matches::debug_assert_matches!(support, SPAWN | NO);
514 }
515 } else {
516 if self.get_create_pidfd() {
517 unreachable!("only implemented on linux")
518 }
519 }
520 }
521
522 // Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
523 #[cfg(all(target_os = "linux", target_env = "gnu"))]
524 {
525 if let Some(version) = sys::os::glibc_version() {
526 if version < (2, 24) {
527 return Ok(None);
528 }
529 } else {
530 return Ok(None);
531 }
532 }
533
534 // On QNX Neutrino, posix_spawnp can fail with EBADF in case "another thread might have opened
535 // or closed a file descriptor while the posix_spawn() was occurring".
536 // Documentation says "... or try calling posix_spawn() again". This is what we do here.
537 // See also http://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/p/posix_spawn.html
538 #[cfg(target_os = "nto")]
539 unsafe fn retrying_libc_posix_spawnp(
540 pid: *mut pid_t,
541 file: *const c_char,
542 file_actions: *const posix_spawn_file_actions_t,
543 attrp: *const posix_spawnattr_t,
544 argv: *const *mut c_char,
545 envp: *const *mut c_char,
546 ) -> io::Result<i32> {
547 let mut delay = MIN_FORKSPAWN_SLEEP;
548 loop {
549 match libc::posix_spawnp(pid, file, file_actions, attrp, argv, envp) {
550 libc::EBADF => {
551 if delay < get_clock_resolution() {
552 // We cannot sleep this short (it would be longer).
553 // Yield instead.
554 thread::yield_now();
555 } else if delay < MAX_FORKSPAWN_SLEEP {
556 thread::sleep(delay);
557 } else {
558 return Err(io::const_error!(
559 ErrorKind::WouldBlock,
560 "posix_spawnp returned EBADF too often",
561 ));
562 }
563 delay *= 2;
564 continue;
565 }
566 r => {
567 return Ok(r);
568 }
569 }
570 }
571 }
572
573 type PosixSpawnAddChdirFn = unsafe extern "C" fn(
574 *mut libc::posix_spawn_file_actions_t,
575 *const libc::c_char,
576 ) -> libc::c_int;
577
578 /// Get the function pointer for adding a chdir action to a
579 /// `posix_spawn_file_actions_t`, if available, assuming a dynamic libc.
580 ///
581 /// Some platforms can set a new working directory for a spawned process in the
582 /// `posix_spawn` path. This function looks up the function pointer for adding
583 /// such an action to a `posix_spawn_file_actions_t` struct.
584 #[cfg(not(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin")))]
585 fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
586 use crate::sys::weak::weak;
587
588 // POSIX.1-2024 standardizes this function:
589 // https://pubs.opengroup.org/onlinepubs/9799919799/functions/posix_spawn_file_actions_addchdir.html.
590 // The _np version is more widely available, though, so try that first.
591
592 weak!(
593 fn posix_spawn_file_actions_addchdir_np(
594 file_actions: *mut libc::posix_spawn_file_actions_t,
595 path: *const libc::c_char,
596 ) -> libc::c_int;
597 );
598
599 weak!(
600 fn posix_spawn_file_actions_addchdir(
601 file_actions: *mut libc::posix_spawn_file_actions_t,
602 path: *const libc::c_char,
603 ) -> libc::c_int;
604 );
605
606 posix_spawn_file_actions_addchdir_np
607 .get()
608 .or_else(|| posix_spawn_file_actions_addchdir.get())
609 }
610
611 /// Get the function pointer for adding a chdir action to a
612 /// `posix_spawn_file_actions_t`, if available, on platforms where the function
613 /// is known to exist.
614 ///
615 /// Weak symbol lookup doesn't work with statically linked libcs, so in cases
616 /// where static linking is possible we need to either check for the presence
617 /// of the symbol at compile time or know about it upfront.
618 ///
619 /// Cygwin doesn't support weak symbol, so just link it.
620 #[cfg(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin"))]
621 fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
622 // Our minimum required musl supports this function, so we can just use it.
623 Some(libc::posix_spawn_file_actions_addchdir_np)
624 }
625
626 let addchdir = match self.get_cwd() {
627 Some(cwd) => {
628 if cfg!(target_vendor = "apple") {
629 // There is a bug in macOS where a relative executable
630 // path like "../myprogram" will cause `posix_spawn` to
631 // successfully launch the program, but erroneously return
632 // ENOENT when used with posix_spawn_file_actions_addchdir_np
633 // which was introduced in macOS 10.15.
634 if self.get_program_kind() == ProgramKind::Relative {
635 return Ok(None);
636 }
637 }
638 // Check for the availability of the posix_spawn addchdir
639 // function now. If it isn't available, bail and use the
640 // fork/exec path.
641 match get_posix_spawn_addchdir() {
642 Some(f) => Some((f, cwd)),
643 None => return Ok(None),
644 }
645 }
646 None => None,
647 };
648
649 let pgroup = self.get_pgroup();
650
651 struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
652
653 impl Drop for PosixSpawnFileActions<'_> {
654 fn drop(&mut self) {
655 unsafe {
656 libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
657 }
658 }
659 }
660
661 struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
662
663 impl Drop for PosixSpawnattr<'_> {
664 fn drop(&mut self) {
665 unsafe {
666 libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
667 }
668 }
669 }
670
671 unsafe {
672 let mut attrs = MaybeUninit::uninit();
673 cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
674 let attrs = PosixSpawnattr(&mut attrs);
675
676 let mut flags = 0;
677
678 let mut file_actions = MaybeUninit::uninit();
679 cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
680 let file_actions = PosixSpawnFileActions(&mut file_actions);
681
682 if let Some(fd) = stdio.stdin.fd() {
683 cvt_nz(libc::posix_spawn_file_actions_adddup2(
684 file_actions.0.as_mut_ptr(),
685 fd,
686 libc::STDIN_FILENO,
687 ))?;
688 }
689 if let Some(fd) = stdio.stdout.fd() {
690 cvt_nz(libc::posix_spawn_file_actions_adddup2(
691 file_actions.0.as_mut_ptr(),
692 fd,
693 libc::STDOUT_FILENO,
694 ))?;
695 }
696 if let Some(fd) = stdio.stderr.fd() {
697 cvt_nz(libc::posix_spawn_file_actions_adddup2(
698 file_actions.0.as_mut_ptr(),
699 fd,
700 libc::STDERR_FILENO,
701 ))?;
702 }
703 if let Some((f, cwd)) = addchdir {
704 cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
705 }
706
707 if let Some(pgroup) = pgroup {
708 flags |= libc::POSIX_SPAWN_SETPGROUP;
709 cvt_nz(libc::posix_spawnattr_setpgroup(attrs.0.as_mut_ptr(), pgroup))?;
710 }
711
712 // Inherit the signal mask from this process rather than resetting it (i.e. do not call
713 // posix_spawnattr_setsigmask).
714
715 // If -Zon-broken-pipe is used, don't reset SIGPIPE to SIG_DFL.
716 // If -Zon-broken-pipe is not used, reset SIGPIPE to SIG_DFL for backward compatibility.
717 //
718 // -Zon-broken-pipe is an opportunity to change the default here.
719 if !on_broken_pipe_flag_used() {
720 let mut default_set = MaybeUninit::<libc::sigset_t>::uninit();
721 cvt(sigemptyset(default_set.as_mut_ptr()))?;
722 cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGPIPE))?;
723 #[cfg(target_os = "hurd")]
724 {
725 cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGLOST))?;
726 }
727 cvt_nz(libc::posix_spawnattr_setsigdefault(
728 attrs.0.as_mut_ptr(),
729 default_set.as_ptr(),
730 ))?;
731 flags |= libc::POSIX_SPAWN_SETSIGDEF;
732 }
733
734 cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
735
736 // Make sure we synchronize access to the global `environ` resource
737 let _env_lock = sys::env::env_read_lock();
738 let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::env::environ() as *const _);
739
740 #[cfg(not(target_os = "nto"))]
741 let spawn_fn = libc::posix_spawnp;
742 #[cfg(target_os = "nto")]
743 let spawn_fn = retrying_libc_posix_spawnp;
744
745 #[cfg(target_os = "linux")]
746 if self.get_create_pidfd() && PIDFD_SUPPORTED.load(Ordering::Relaxed) == SPAWN {
747 let mut pidfd: libc::c_int = -1;
748 let spawn_res = pidfd_spawnp.get().unwrap()(
749 &mut pidfd,
750 self.get_program_cstr().as_ptr(),
751 file_actions.0.as_ptr(),
752 attrs.0.as_ptr(),
753 self.get_argv().as_ptr() as *const _,
754 envp as *const _,
755 );
756
757 let spawn_res = cvt_nz(spawn_res);
758 if let Err(ref e) = spawn_res
759 && e.raw_os_error() == Some(libc::ENOSYS)
760 {
761 PIDFD_SUPPORTED.store(FORK_EXEC, Ordering::Relaxed);
762 return Ok(None);
763 }
764 spawn_res?;
765
766 let pid = match cvt(pidfd_getpid.get().unwrap()(pidfd)) {
767 Ok(pid) => pid,
768 Err(e) => {
769 // The child has been spawned and we are holding its pidfd.
770 // But we cannot obtain its pid even though pidfd_getpid support was verified earlier.
771 // This might happen if libc can't open procfs because the file descriptor limit has been reached.
772 libc::close(pidfd);
773 return Err(Error::new(
774 e.kind(),
775 "pidfd_spawnp succeeded but the child's PID could not be obtained",
776 ));
777 }
778 };
779
780 return Ok(Some(Process::new(pid, pidfd)));
781 }
782
783 // Safety: -1 indicates we don't have a pidfd.
784 let mut p = Process::new(0, -1);
785
786 let spawn_res = spawn_fn(
787 &mut p.pid,
788 self.get_program_cstr().as_ptr(),
789 file_actions.0.as_ptr(),
790 attrs.0.as_ptr(),
791 self.get_argv().as_ptr() as *const _,
792 envp as *const _,
793 );
794
795 #[cfg(target_os = "nto")]
796 let spawn_res = spawn_res?;
797
798 cvt_nz(spawn_res)?;
799 Ok(Some(p))
800 }
801 }
802
803 #[cfg(target_os = "linux")]
804 fn send_pidfd(&self, sock: &crate::sys:🥅:Socket) {
805 use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
806
807 use crate::io::IoSlice;
808 use crate::os::fd::RawFd;
809 use crate::sys::cvt_r;
810
811 unsafe {
812 let child_pid = libc::getpid();
813 // pidfd_open sets CLOEXEC by default
814 let pidfd = libc::syscall(libc::SYS_pidfd_open, child_pid, 0);
815
816 let fds: [c_int; 1] = [pidfd as RawFd];
817
818 const SCM_MSG_LEN: usize = size_of::<[c_int; 1]>();
819
820 #[repr(C)]
821 union Cmsg {
822 buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
823 _align: libc::cmsghdr,
824 }
825
826 let mut cmsg: Cmsg = mem::zeroed();
827
828 // 0-length message to send through the socket so we can pass along the fd
829 let mut iov = [IoSlice::new(b"")];
830 let mut msg: libc::msghdr = mem::zeroed();
831
832 msg.msg_iov = (&raw mut iov) as *mut _;
833 msg.msg_iovlen = 1;
834
835 // only attach cmsg if we successfully acquired the pidfd
836 if pidfd >= 0 {
837 msg.msg_controllen = size_of_val(&cmsg.buf) as _;
838 msg.msg_control = (&raw mut cmsg.buf) as *mut _;
839
840 let hdr = CMSG_FIRSTHDR((&raw mut msg) as *mut _);
841 (*hdr).cmsg_level = SOL_SOCKET;
842 (*hdr).cmsg_type = SCM_RIGHTS;
843 (*hdr).cmsg_len = CMSG_LEN(SCM_MSG_LEN as _) as _;
844 let data = CMSG_DATA(hdr);
845 crate::ptr::copy_nonoverlapping(
846 fds.as_ptr().cast::<u8>(),
847 data as *mut _,
848 SCM_MSG_LEN,
849 );
850 }
851
852 // we send the 0-length message even if we failed to acquire the pidfd
853 // so we get a consistent SEQPACKET order
854 match cvt_r(|| libc::sendmsg(sock.as_raw(), &msg, 0)) {
855 Ok(0) => {}
856 other => rtabort!("failed to communicate with parent process. {:?}", other),
857 }
858 }
859 }
860
861 #[cfg(target_os = "linux")]
862 fn recv_pidfd(&self, sock: &crate::sys:🥅:Socket) -> pid_t {
863 use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
864
865 use crate::io::IoSliceMut;
866 use crate::sys::cvt_r;
867
868 unsafe {
869 const SCM_MSG_LEN: usize = size_of::<[c_int; 1]>();
870
871 #[repr(C)]
872 union Cmsg {
873 _buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
874 _align: libc::cmsghdr,
875 }
876 let mut cmsg: Cmsg = mem::zeroed();
877 // 0-length read to get the fd
878 let mut iov = [IoSliceMut::new(&mut [])];
879
880 let mut msg: libc::msghdr = mem::zeroed();
881
882 msg.msg_iov = (&raw mut iov) as *mut _;
883 msg.msg_iovlen = 1;
884 msg.msg_controllen = size_of::<Cmsg>() as _;
885 msg.msg_control = (&raw mut cmsg) as *mut _;
886
887 match cvt_r(|| libc::recvmsg(sock.as_raw(), &mut msg, libc::MSG_CMSG_CLOEXEC)) {
888 Err(_) => return -1,
889 Ok(_) => {}
890 }
891
892 let hdr = CMSG_FIRSTHDR((&raw mut msg) as *mut _);
893 if hdr.is_null()
894 || (*hdr).cmsg_level != SOL_SOCKET
895 || (*hdr).cmsg_type != SCM_RIGHTS
896 || (*hdr).cmsg_len != CMSG_LEN(SCM_MSG_LEN as _) as _
897 {
898 return -1;
899 }
900 let data = CMSG_DATA(hdr);
901
902 let mut fds = [-1 as c_int];
903
904 crate::ptr::copy_nonoverlapping(
905 data as *const _,
906 fds.as_mut_ptr().cast::<u8>(),
907 SCM_MSG_LEN,
908 );
909
910 fds[0]
911 }
912 }
913}
914
915////////////////////////////////////////////////////////////////////////////////
916// Processes
917////////////////////////////////////////////////////////////////////////////////
918
919/// The unique ID of the process (this should never be negative).
920pub struct Process {
921 pid: pid_t,
922 status: Option<ExitStatus>,
923 // On Linux, stores the pidfd created for this child.
924 // This is None if the user did not request pidfd creation,
925 // or if the pidfd could not be created for some reason
926 // (e.g. the `pidfd_open` syscall was not available).
927 #[cfg(target_os = "linux")]
928 pidfd: Option<PidFd>,
929}
930
931impl Process {
932 #[cfg(target_os = "linux")]
933 /// # Safety
934 ///
935 /// `pidfd` must either be -1 (representing no file descriptor) or a valid, exclusively owned file
936 /// descriptor (See [I/O Safety]).
937 ///
938 /// [I/O Safety]: crate::io#io-safety
939 unsafe fn new(pid: pid_t, pidfd: pid_t) -> Self {
940 use crate::os::unix::io::FromRawFd;
941 use crate::sys_common::FromInner;
942 // Safety: If `pidfd` is nonnegative, we assume it's valid and otherwise unowned.
943 let pidfd = (pidfd >= 0).then(|| PidFd::from_inner(sys::fd::FileDesc::from_raw_fd(pidfd)));
944 Process { pid, status: None, pidfd }
945 }
946
947 #[cfg(not(target_os = "linux"))]
948 unsafe fn new(pid: pid_t, _pidfd: pid_t) -> Self {
949 Process { pid, status: None }
950 }
951
952 pub fn id(&self) -> u32 {
953 self.pid as u32
954 }
955
956 pub fn kill(&mut self) -> io::Result<()> {
957 // If we've already waited on this process then the pid can be recycled
958 // and used for another process, and we probably shouldn't be killing
959 // random processes, so return Ok because the process has exited already.
960 if self.status.is_some() {
961 return Ok(());
962 }
963 #[cfg(target_os = "linux")]
964 if let Some(pid_fd) = self.pidfd.as_ref() {
965 // pidfd_send_signal predates pidfd_open. so if we were able to get an fd then sending signals will work too
966 return pid_fd.kill();
967 }
968 cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
969 }
970
971 pub fn wait(&mut self) -> io::Result<ExitStatus> {
972 use crate::sys::cvt_r;
973 if let Some(status) = self.status {
974 return Ok(status);
975 }
976 #[cfg(target_os = "linux")]
977 if let Some(pid_fd) = self.pidfd.as_ref() {
978 let status = pid_fd.wait()?;
979 self.status = Some(status);
980 return Ok(status);
981 }
982 let mut status = 0 as c_int;
983 cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
984 self.status = Some(ExitStatus::new(status));
985 Ok(ExitStatus::new(status))
986 }
987
988 pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
989 if let Some(status) = self.status {
990 return Ok(Some(status));
991 }
992 #[cfg(target_os = "linux")]
993 if let Some(pid_fd) = self.pidfd.as_ref() {
994 let status = pid_fd.try_wait()?;
995 if let Some(status) = status {
996 self.status = Some(status)
997 }
998 return Ok(status);
999 }
1000 let mut status = 0 as c_int;
1001 let pid = cvt(unsafe { libc::waitpid(self.pid, &mut status, libc::WNOHANG) })?;
1002 if pid == 0 {
1003 Ok(None)
1004 } else {
1005 self.status = Some(ExitStatus::new(status));
1006 Ok(Some(ExitStatus::new(status)))
1007 }
1008 }
1009}
1010
1011/// Unix exit statuses
1012//
1013// This is not actually an "exit status" in Unix terminology. Rather, it is a "wait status".
1014// See the discussion in comments and doc comments for `std::process::ExitStatus`.
1015#[derive(PartialEq, Eq, Clone, Copy, Default)]
1016pub struct ExitStatus(c_int);
1017
1018impl fmt::Debug for ExitStatus {
1019 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1020 f.debug_tuple("unix_wait_status").field(&self.0).finish()
1021 }
1022}
1023
1024impl ExitStatus {
1025 pub fn new(status: c_int) -> ExitStatus {
1026 ExitStatus(status)
1027 }
1028
1029 #[cfg(target_os = "linux")]
1030 pub fn from_waitid_siginfo(siginfo: libc::siginfo_t) -> ExitStatus {
1031 let status = unsafe { siginfo.si_status() };
1032
1033 match siginfo.si_code {
1034 libc::CLD_EXITED => ExitStatus((status & 0xff) << 8),
1035 libc::CLD_KILLED => ExitStatus(status),
1036 libc::CLD_DUMPED => ExitStatus(status | 0x80),
1037 libc::CLD_CONTINUED => ExitStatus(0xffff),
1038 libc::CLD_STOPPED | libc::CLD_TRAPPED => ExitStatus(((status & 0xff) << 8) | 0x7f),
1039 _ => unreachable!("waitid() should only return the above codes"),
1040 }
1041 }
1042
1043 fn exited(&self) -> bool {
1044 libc::WIFEXITED(self.0)
1045 }
1046
1047 pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
1048 // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is
1049 // true on all actual versions of Unix, is widely assumed, and is specified in SuS
1050 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html. If it is not
1051 // true for a platform pretending to be Unix, the tests (our doctests, and also
1052 // unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too.
1053 match NonZero::try_from(self.0) {
1054 /* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)),
1055 /* was zero, couldn't convert */ Err(_) => Ok(()),
1056 }
1057 }
1058
1059 pub fn code(&self) -> Option<i32> {
1060 self.exited().then(|| libc::WEXITSTATUS(self.0))
1061 }
1062
1063 pub fn signal(&self) -> Option<i32> {
1064 libc::WIFSIGNALED(self.0).then(|| libc::WTERMSIG(self.0))
1065 }
1066
1067 pub fn core_dumped(&self) -> bool {
1068 libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
1069 }
1070
1071 pub fn stopped_signal(&self) -> Option<i32> {
1072 libc::WIFSTOPPED(self.0).then(|| libc::WSTOPSIG(self.0))
1073 }
1074
1075 pub fn continued(&self) -> bool {
1076 libc::WIFCONTINUED(self.0)
1077 }
1078
1079 pub fn into_raw(&self) -> c_int {
1080 self.0
1081 }
1082}
1083
1084/// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
1085impl From<c_int> for ExitStatus {
1086 fn from(a: c_int) -> ExitStatus {
1087 ExitStatus(a)
1088 }
1089}
1090
1091/// Converts a signal number to a readable, searchable name.
1092///
1093/// This string should be displayed right after the signal number.
1094/// If a signal is unrecognized, it returns the empty string, so that
1095/// you just get the number like "0". If it is recognized, you'll get
1096/// something like "9 (SIGKILL)".
1097fn signal_string(signal: i32) -> &'static str {
1098 match signal {
1099 libc::SIGHUP => " (SIGHUP)",
1100 libc::SIGINT => " (SIGINT)",
1101 libc::SIGQUIT => " (SIGQUIT)",
1102 libc::SIGILL => " (SIGILL)",
1103 libc::SIGTRAP => " (SIGTRAP)",
1104 libc::SIGABRT => " (SIGABRT)",
1105 #[cfg(not(target_os = "l4re"))]
1106 libc::SIGBUS => " (SIGBUS)",
1107 libc::SIGFPE => " (SIGFPE)",
1108 libc::SIGKILL => " (SIGKILL)",
1109 #[cfg(not(target_os = "l4re"))]
1110 libc::SIGUSR1 => " (SIGUSR1)",
1111 libc::SIGSEGV => " (SIGSEGV)",
1112 #[cfg(not(target_os = "l4re"))]
1113 libc::SIGUSR2 => " (SIGUSR2)",
1114 libc::SIGPIPE => " (SIGPIPE)",
1115 libc::SIGALRM => " (SIGALRM)",
1116 libc::SIGTERM => " (SIGTERM)",
1117 #[cfg(not(target_os = "l4re"))]
1118 libc::SIGCHLD => " (SIGCHLD)",
1119 #[cfg(not(target_os = "l4re"))]
1120 libc::SIGCONT => " (SIGCONT)",
1121 #[cfg(not(target_os = "l4re"))]
1122 libc::SIGSTOP => " (SIGSTOP)",
1123 #[cfg(not(target_os = "l4re"))]
1124 libc::SIGTSTP => " (SIGTSTP)",
1125 #[cfg(not(target_os = "l4re"))]
1126 libc::SIGTTIN => " (SIGTTIN)",
1127 #[cfg(not(target_os = "l4re"))]
1128 libc::SIGTTOU => " (SIGTTOU)",
1129 #[cfg(not(target_os = "l4re"))]
1130 libc::SIGURG => " (SIGURG)",
1131 #[cfg(not(target_os = "l4re"))]
1132 libc::SIGXCPU => " (SIGXCPU)",
1133 #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1134 libc::SIGXFSZ => " (SIGXFSZ)",
1135 #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1136 libc::SIGVTALRM => " (SIGVTALRM)",
1137 #[cfg(not(target_os = "l4re"))]
1138 libc::SIGPROF => " (SIGPROF)",
1139 #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1140 libc::SIGWINCH => " (SIGWINCH)",
1141 #[cfg(not(any(target_os = "haiku", target_os = "l4re")))]
1142 libc::SIGIO => " (SIGIO)",
1143 #[cfg(target_os = "haiku")]
1144 libc::SIGPOLL => " (SIGPOLL)",
1145 #[cfg(not(target_os = "l4re"))]
1146 libc::SIGSYS => " (SIGSYS)",
1147 // For information on Linux signals, run `man 7 signal`
1148 #[cfg(all(
1149 target_os = "linux",
1150 any(
1151 target_arch = "x86_64",
1152 target_arch = "x86",
1153 target_arch = "arm",
1154 target_arch = "aarch64"
1155 )
1156 ))]
1157 libc::SIGSTKFLT => " (SIGSTKFLT)",
1158 #[cfg(any(target_os = "linux", target_os = "nto", target_os = "cygwin"))]
1159 libc::SIGPWR => " (SIGPWR)",
1160 #[cfg(any(
1161 target_os = "freebsd",
1162 target_os = "netbsd",
1163 target_os = "openbsd",
1164 target_os = "dragonfly",
1165 target_os = "nto",
1166 target_vendor = "apple",
1167 target_os = "cygwin",
1168 ))]
1169 libc::SIGEMT => " (SIGEMT)",
1170 #[cfg(any(
1171 target_os = "freebsd",
1172 target_os = "netbsd",
1173 target_os = "openbsd",
1174 target_os = "dragonfly",
1175 target_vendor = "apple",
1176 ))]
1177 libc::SIGINFO => " (SIGINFO)",
1178 #[cfg(target_os = "hurd")]
1179 libc::SIGLOST => " (SIGLOST)",
1180 #[cfg(target_os = "freebsd")]
1181 libc::SIGTHR => " (SIGTHR)",
1182 #[cfg(target_os = "freebsd")]
1183 libc::SIGLIBRT => " (SIGLIBRT)",
1184 _ => "",
1185 }
1186}
1187
1188impl fmt::Display for ExitStatus {
1189 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1190 if let Some(code) = self.code() {
1191 write!(f, "exit status: {code}")
1192 } else if let Some(signal) = self.signal() {
1193 let signal_string = signal_string(signal);
1194 if self.core_dumped() {
1195 write!(f, "signal: {signal}{signal_string} (core dumped)")
1196 } else {
1197 write!(f, "signal: {signal}{signal_string}")
1198 }
1199 } else if let Some(signal) = self.stopped_signal() {
1200 let signal_string = signal_string(signal);
1201 write!(f, "stopped (not terminated) by signal: {signal}{signal_string}")
1202 } else if self.continued() {
1203 write!(f, "continued (WIFCONTINUED)")
1204 } else {
1205 write!(f, "unrecognised wait status: {} {:#x}", self.0, self.0)
1206 }
1207 }
1208}
1209
1210#[derive(PartialEq, Eq, Clone, Copy)]
1211pub struct ExitStatusError(NonZero<c_int>);
1212
1213impl Into<ExitStatus> for ExitStatusError {
1214 fn into(self) -> ExitStatus {
1215 ExitStatus(self.0.into())
1216 }
1217}
1218
1219impl fmt::Debug for ExitStatusError {
1220 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1221 f.debug_tuple("unix_wait_status").field(&self.0).finish()
1222 }
1223}
1224
1225impl ExitStatusError {
1226 pub fn code(self) -> Option<NonZero<i32>> {
1227 ExitStatus(self.0.into()).code().map(|st| st.try_into().unwrap())
1228 }
1229}
1230
1231#[cfg(target_os = "linux")]
1232mod linux_child_ext {
1233 use crate::io::ErrorKind;
1234 use crate::os::linux::process as os;
1235 use crate::sys::pal::linux::pidfd as imp;
1236 use crate::sys_common::FromInner;
1237 use crate::{io, mem};
1238
1239 #[unstable(feature = "linux_pidfd", issue = "82971")]
1240 impl crate::os::linux::process::ChildExt for crate::process::Child {
1241 fn pidfd(&self) -> io::Result<&os::PidFd> {
1242 self.handle
1243 .pidfd
1244 .as_ref()
1245 // SAFETY: The os type is a transparent wrapper, therefore we can transmute references
1246 .map(|fd| unsafe { mem::transmute::<&imp::PidFd, &os::PidFd>(fd) })
1247 .ok_or_else(|| io::const_error!(ErrorKind::Uncategorized, "no pidfd was created."))
1248 }
1249
1250 fn into_pidfd(mut self) -> Result<os::PidFd, Self> {
1251 self.handle
1252 .pidfd
1253 .take()
1254 .map(|fd| <os::PidFd as FromInner<imp::PidFd>>::from_inner(fd))
1255 .ok_or_else(|| self)
1256 }
1257 }
1258}
1259
1260#[cfg(test)]
1261mod tests;
1262
1263// See [`unsupported_wait_status::compare_with_linux`];
1264#[cfg(all(test, target_os = "linux"))]
1265#[path = "unsupported/wait_status.rs"]
1266mod unsupported_wait_status;