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::net::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    pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> {
166        let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?;
167        crate::sys_common::process::wait_with_output(proc, pipes)
168    }
169
170    // WatchOS and TVOS headers mark the `fork`/`exec*` functions with
171    // `__WATCHOS_PROHIBITED __TVOS_PROHIBITED`, and indicate that the
172    // `posix_spawn*` functions should be used instead. It isn't entirely clear
173    // what `PROHIBITED` means here (e.g. if calls to these functions are
174    // allowed to exist in dead code), but it sounds bad, so we go out of our
175    // way to avoid that all-together.
176    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
177    const ERR_APPLE_TV_WATCH_NO_FORK_EXEC: Error = io::const_error!(
178        ErrorKind::Unsupported,
179        "`fork`+`exec`-based process spawning is not supported on this target",
180    );
181
182    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
183    unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
184        return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
185    }
186
187    // Attempts to fork the process. If successful, returns Ok((0, -1))
188    // in the child, and Ok((child_pid, -1)) in the parent.
189    #[cfg(not(any(target_os = "watchos", target_os = "tvos", target_os = "nto")))]
190    unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
191        cvt(libc::fork())
192    }
193
194    // On QNX Neutrino, fork can fail with EBADF in case "another thread might have opened
195    // or closed a file descriptor while the fork() was occurring".
196    // Documentation says "... or try calling fork() again". This is what we do here.
197    // See also https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/f/fork.html
198    #[cfg(target_os = "nto")]
199    unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
200        use crate::sys::os::errno;
201
202        let mut delay = MIN_FORKSPAWN_SLEEP;
203
204        loop {
205            let r = libc::fork();
206            if r == -1 as libc::pid_t && errno() as libc::c_int == libc::EBADF {
207                if delay < get_clock_resolution() {
208                    // We cannot sleep this short (it would be longer).
209                    // Yield instead.
210                    thread::yield_now();
211                } else if delay < MAX_FORKSPAWN_SLEEP {
212                    thread::sleep(delay);
213                } else {
214                    return Err(io::const_error!(
215                        ErrorKind::WouldBlock,
216                        "forking returned EBADF too often",
217                    ));
218                }
219                delay *= 2;
220                continue;
221            } else {
222                return cvt(r);
223            }
224        }
225    }
226
227    pub fn exec(&mut self, default: Stdio) -> io::Error {
228        let envp = self.capture_env();
229
230        if self.saw_nul() {
231            return io::const_error!(ErrorKind::InvalidInput, "nul byte found in provided data");
232        }
233
234        match self.setup_io(default, true) {
235            Ok((_, theirs)) => {
236                unsafe {
237                    // Similar to when forking, we want to ensure that access to
238                    // the environment is synchronized, so make sure to grab the
239                    // environment lock before we try to exec.
240                    let _lock = sys::env::env_read_lock();
241
242                    let Err(e) = self.do_exec(theirs, envp.as_ref());
243                    e
244                }
245            }
246            Err(e) => e,
247        }
248    }
249
250    // And at this point we've reached a special time in the life of the
251    // child. The child must now be considered hamstrung and unable to
252    // do anything other than syscalls really. Consider the following
253    // scenario:
254    //
255    //      1. Thread A of process 1 grabs the malloc() mutex
256    //      2. Thread B of process 1 forks(), creating thread C
257    //      3. Thread C of process 2 then attempts to malloc()
258    //      4. The memory of process 2 is the same as the memory of
259    //         process 1, so the mutex is locked.
260    //
261    // This situation looks a lot like deadlock, right? It turns out
262    // that this is what pthread_atfork() takes care of, which is
263    // presumably implemented across platforms. The first thing that
264    // threads to *before* forking is to do things like grab the malloc
265    // mutex, and then after the fork they unlock it.
266    //
267    // Despite this information, libnative's spawn has been witnessed to
268    // deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
269    // all collected backtraces point at malloc/free traffic in the
270    // child spawned process.
271    //
272    // For this reason, the block of code below should contain 0
273    // invocations of either malloc of free (or their related friends).
274    //
275    // As an example of not having malloc/free traffic, we don't close
276    // this file descriptor by dropping the FileDesc (which contains an
277    // allocation). Instead we just close it manually. This will never
278    // have the drop glue anyway because this code never returns (the
279    // child will either exec() or invoke libc::exit)
280    #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
281    unsafe fn do_exec(
282        &mut self,
283        stdio: ChildPipes,
284        maybe_envp: Option<&CStringArray>,
285    ) -> Result<!, io::Error> {
286        use crate::sys::{self, cvt_r};
287
288        if let Some(fd) = stdio.stdin.fd() {
289            cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
290        }
291        if let Some(fd) = stdio.stdout.fd() {
292            cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
293        }
294        if let Some(fd) = stdio.stderr.fd() {
295            cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
296        }
297
298        #[cfg(not(target_os = "l4re"))]
299        {
300            if let Some(_g) = self.get_groups() {
301                //FIXME: Redox kernel does not support setgroups yet
302                #[cfg(not(target_os = "redox"))]
303                cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
304            }
305            if let Some(u) = self.get_gid() {
306                cvt(libc::setgid(u as gid_t))?;
307            }
308            if let Some(u) = self.get_uid() {
309                // When dropping privileges from root, the `setgroups` call
310                // will remove any extraneous groups. We only drop groups
311                // if we have CAP_SETGID and we weren't given an explicit
312                // set of groups. If we don't call this, then even though our
313                // uid has dropped, we may still have groups that enable us to
314                // do super-user things.
315                //FIXME: Redox kernel does not support setgroups yet
316                #[cfg(not(target_os = "redox"))]
317                if self.get_groups().is_none() {
318                    let res = cvt(libc::setgroups(0, crate::ptr::null()));
319                    if let Err(e) = res {
320                        // Here we ignore the case of not having CAP_SETGID.
321                        // An alternative would be to require CAP_SETGID (in
322                        // addition to CAP_SETUID) for setting the UID.
323                        if e.raw_os_error() != Some(libc::EPERM) {
324                            return Err(e.into());
325                        }
326                    }
327                }
328                cvt(libc::setuid(u as uid_t))?;
329            }
330        }
331        if let Some(cwd) = self.get_cwd() {
332            cvt(libc::chdir(cwd.as_ptr()))?;
333        }
334
335        if let Some(pgroup) = self.get_pgroup() {
336            cvt(libc::setpgid(0, pgroup))?;
337        }
338
339        // emscripten has no signal support.
340        #[cfg(not(target_os = "emscripten"))]
341        {
342            // Inherit the signal mask from the parent rather than resetting it (i.e. do not call
343            // pthread_sigmask).
344
345            // If -Zon-broken-pipe is used, don't reset SIGPIPE to SIG_DFL.
346            // If -Zon-broken-pipe is not used, reset SIGPIPE to SIG_DFL for backward compatibility.
347            //
348            // -Zon-broken-pipe is an opportunity to change the default here.
349            if !crate::sys::pal::on_broken_pipe_flag_used() {
350                #[cfg(target_os = "android")] // see issue #88585
351                {
352                    let mut action: libc::sigaction = mem::zeroed();
353                    action.sa_sigaction = libc::SIG_DFL;
354                    cvt(libc::sigaction(libc::SIGPIPE, &action, crate::ptr::null_mut()))?;
355                }
356                #[cfg(not(target_os = "android"))]
357                {
358                    let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL);
359                    if ret == libc::SIG_ERR {
360                        return Err(io::Error::last_os_error());
361                    }
362                }
363                #[cfg(target_os = "hurd")]
364                {
365                    let ret = sys::signal(libc::SIGLOST, libc::SIG_DFL);
366                    if ret == libc::SIG_ERR {
367                        return Err(io::Error::last_os_error());
368                    }
369                }
370            }
371        }
372
373        for callback in self.get_closures().iter_mut() {
374            callback()?;
375        }
376
377        // Although we're performing an exec here we may also return with an
378        // error from this function (without actually exec'ing) in which case we
379        // want to be sure to restore the global environment back to what it
380        // once was, ensuring that our temporary override, when free'd, doesn't
381        // corrupt our process's environment.
382        let mut _reset = None;
383        if let Some(envp) = maybe_envp {
384            struct Reset(*const *const libc::c_char);
385
386            impl Drop for Reset {
387                fn drop(&mut self) {
388                    unsafe {
389                        *sys::env::environ() = self.0;
390                    }
391                }
392            }
393
394            _reset = Some(Reset(*sys::env::environ()));
395            *sys::env::environ() = envp.as_ptr();
396        }
397
398        libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr());
399        Err(io::Error::last_os_error())
400    }
401
402    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
403    unsafe fn do_exec(
404        &mut self,
405        _stdio: ChildPipes,
406        _maybe_envp: Option<&CStringArray>,
407    ) -> Result<!, io::Error> {
408        return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
409    }
410
411    #[cfg(not(any(
412        target_os = "freebsd",
413        target_os = "illumos",
414        all(target_os = "linux", target_env = "gnu"),
415        all(target_os = "linux", target_env = "musl"),
416        target_os = "nto",
417        target_vendor = "apple",
418        target_os = "cygwin",
419    )))]
420    fn posix_spawn(
421        &mut self,
422        _: &ChildPipes,
423        _: Option<&CStringArray>,
424    ) -> io::Result<Option<Process>> {
425        Ok(None)
426    }
427
428    // Only support platforms for which posix_spawn() can return ENOENT
429    // directly.
430    #[cfg(any(
431        target_os = "freebsd",
432        target_os = "illumos",
433        all(target_os = "linux", target_env = "gnu"),
434        all(target_os = "linux", target_env = "musl"),
435        target_os = "nto",
436        target_vendor = "apple",
437        target_os = "cygwin",
438    ))]
439    fn posix_spawn(
440        &mut self,
441        stdio: &ChildPipes,
442        envp: Option<&CStringArray>,
443    ) -> io::Result<Option<Process>> {
444        #[cfg(target_os = "linux")]
445        use core::sync::atomic::{Atomic, AtomicU8, Ordering};
446
447        use crate::mem::MaybeUninit;
448        use crate::sys::{self, cvt_nz, on_broken_pipe_flag_used};
449
450        if self.get_gid().is_some()
451            || self.get_uid().is_some()
452            || (self.env_saw_path() && !self.program_is_path())
453            || !self.get_closures().is_empty()
454            || self.get_groups().is_some()
455        {
456            return Ok(None);
457        }
458
459        cfg_if::cfg_if! {
460            if #[cfg(target_os = "linux")] {
461                use crate::sys::weak::weak;
462
463                weak!(
464                    fn pidfd_spawnp(
465                        pidfd: *mut libc::c_int,
466                        path: *const libc::c_char,
467                        file_actions: *const libc::posix_spawn_file_actions_t,
468                        attrp: *const libc::posix_spawnattr_t,
469                        argv: *const *mut libc::c_char,
470                        envp: *const *mut libc::c_char,
471                    ) -> libc::c_int;
472                );
473
474                weak!(
475                    fn pidfd_getpid(pidfd: libc::c_int) -> libc::c_int;
476                );
477
478                static PIDFD_SUPPORTED: Atomic<u8> = AtomicU8::new(0);
479                const UNKNOWN: u8 = 0;
480                const SPAWN: u8 = 1;
481                // Obtaining a pidfd via the fork+exec path might work
482                const FORK_EXEC: u8 = 2;
483                // Neither pidfd_spawn nor fork/exec will get us a pidfd.
484                // Instead we'll just posix_spawn if the other preconditions are met.
485                const NO: u8 = 3;
486
487                if self.get_create_pidfd() {
488                    let mut support = PIDFD_SUPPORTED.load(Ordering::Relaxed);
489                    if support == FORK_EXEC {
490                        return Ok(None);
491                    }
492                    if support == UNKNOWN {
493                        support = NO;
494                        let our_pid = crate::process::id();
495                        let pidfd = cvt(unsafe { libc::syscall(libc::SYS_pidfd_open, our_pid, 0) } as c_int);
496                        match pidfd {
497                            Ok(pidfd) => {
498                                support = FORK_EXEC;
499                                if let Some(Ok(pid)) = pidfd_getpid.get().map(|f| cvt(unsafe { f(pidfd) } as i32)) {
500                                    if pidfd_spawnp.get().is_some() && pid as u32 == our_pid {
501                                        support = SPAWN
502                                    }
503                                }
504                                unsafe { libc::close(pidfd) };
505                            }
506                            Err(e) if e.raw_os_error() == Some(libc::EMFILE) => {
507                                // We're temporarily(?) out of file descriptors.  In this case obtaining a pidfd would also fail
508                                // Don't update the support flag so we can probe again later.
509                                return Err(e)
510                            }
511                            _ => {}
512                        }
513                        PIDFD_SUPPORTED.store(support, Ordering::Relaxed);
514                        if support == FORK_EXEC {
515                            return Ok(None);
516                        }
517                    }
518                    core::assert_matches::debug_assert_matches!(support, SPAWN | NO);
519                }
520            } else {
521                if self.get_create_pidfd() {
522                    unreachable!("only implemented on linux")
523                }
524            }
525        }
526
527        // Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
528        #[cfg(all(target_os = "linux", target_env = "gnu"))]
529        {
530            if let Some(version) = sys::os::glibc_version() {
531                if version < (2, 24) {
532                    return Ok(None);
533                }
534            } else {
535                return Ok(None);
536            }
537        }
538
539        // On QNX Neutrino, posix_spawnp can fail with EBADF in case "another thread might have opened
540        // or closed a file descriptor while the posix_spawn() was occurring".
541        // Documentation says "... or try calling posix_spawn() again". This is what we do here.
542        // See also http://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/p/posix_spawn.html
543        #[cfg(target_os = "nto")]
544        unsafe fn retrying_libc_posix_spawnp(
545            pid: *mut pid_t,
546            file: *const c_char,
547            file_actions: *const posix_spawn_file_actions_t,
548            attrp: *const posix_spawnattr_t,
549            argv: *const *mut c_char,
550            envp: *const *mut c_char,
551        ) -> io::Result<i32> {
552            let mut delay = MIN_FORKSPAWN_SLEEP;
553            loop {
554                match libc::posix_spawnp(pid, file, file_actions, attrp, argv, envp) {
555                    libc::EBADF => {
556                        if delay < get_clock_resolution() {
557                            // We cannot sleep this short (it would be longer).
558                            // Yield instead.
559                            thread::yield_now();
560                        } else if delay < MAX_FORKSPAWN_SLEEP {
561                            thread::sleep(delay);
562                        } else {
563                            return Err(io::const_error!(
564                                ErrorKind::WouldBlock,
565                                "posix_spawnp returned EBADF too often",
566                            ));
567                        }
568                        delay *= 2;
569                        continue;
570                    }
571                    r => {
572                        return Ok(r);
573                    }
574                }
575            }
576        }
577
578        type PosixSpawnAddChdirFn = unsafe extern "C" fn(
579            *mut libc::posix_spawn_file_actions_t,
580            *const libc::c_char,
581        ) -> libc::c_int;
582
583        /// Get the function pointer for adding a chdir action to a
584        /// `posix_spawn_file_actions_t`, if available, assuming a dynamic libc.
585        ///
586        /// Some platforms can set a new working directory for a spawned process in the
587        /// `posix_spawn` path. This function looks up the function pointer for adding
588        /// such an action to a `posix_spawn_file_actions_t` struct.
589        #[cfg(not(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin")))]
590        fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
591            use crate::sys::weak::weak;
592
593            // POSIX.1-2024 standardizes this function:
594            // https://pubs.opengroup.org/onlinepubs/9799919799/functions/posix_spawn_file_actions_addchdir.html.
595            // The _np version is more widely available, though, so try that first.
596
597            weak!(
598                fn posix_spawn_file_actions_addchdir_np(
599                    file_actions: *mut libc::posix_spawn_file_actions_t,
600                    path: *const libc::c_char,
601                ) -> libc::c_int;
602            );
603
604            weak!(
605                fn posix_spawn_file_actions_addchdir(
606                    file_actions: *mut libc::posix_spawn_file_actions_t,
607                    path: *const libc::c_char,
608                ) -> libc::c_int;
609            );
610
611            posix_spawn_file_actions_addchdir_np
612                .get()
613                .or_else(|| posix_spawn_file_actions_addchdir.get())
614        }
615
616        /// Get the function pointer for adding a chdir action to a
617        /// `posix_spawn_file_actions_t`, if available, on platforms where the function
618        /// is known to exist.
619        ///
620        /// Weak symbol lookup doesn't work with statically linked libcs, so in cases
621        /// where static linking is possible we need to either check for the presence
622        /// of the symbol at compile time or know about it upfront.
623        ///
624        /// Cygwin doesn't support weak symbol, so just link it.
625        #[cfg(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin"))]
626        fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
627            // Our minimum required musl supports this function, so we can just use it.
628            Some(libc::posix_spawn_file_actions_addchdir_np)
629        }
630
631        let addchdir = match self.get_cwd() {
632            Some(cwd) => {
633                if cfg!(target_vendor = "apple") {
634                    // There is a bug in macOS where a relative executable
635                    // path like "../myprogram" will cause `posix_spawn` to
636                    // successfully launch the program, but erroneously return
637                    // ENOENT when used with posix_spawn_file_actions_addchdir_np
638                    // which was introduced in macOS 10.15.
639                    if self.get_program_kind() == ProgramKind::Relative {
640                        return Ok(None);
641                    }
642                }
643                // Check for the availability of the posix_spawn addchdir
644                // function now. If it isn't available, bail and use the
645                // fork/exec path.
646                match get_posix_spawn_addchdir() {
647                    Some(f) => Some((f, cwd)),
648                    None => return Ok(None),
649                }
650            }
651            None => None,
652        };
653
654        let pgroup = self.get_pgroup();
655
656        struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
657
658        impl Drop for PosixSpawnFileActions<'_> {
659            fn drop(&mut self) {
660                unsafe {
661                    libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
662                }
663            }
664        }
665
666        struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
667
668        impl Drop for PosixSpawnattr<'_> {
669            fn drop(&mut self) {
670                unsafe {
671                    libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
672                }
673            }
674        }
675
676        unsafe {
677            let mut attrs = MaybeUninit::uninit();
678            cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
679            let attrs = PosixSpawnattr(&mut attrs);
680
681            let mut flags = 0;
682
683            let mut file_actions = MaybeUninit::uninit();
684            cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
685            let file_actions = PosixSpawnFileActions(&mut file_actions);
686
687            if let Some(fd) = stdio.stdin.fd() {
688                cvt_nz(libc::posix_spawn_file_actions_adddup2(
689                    file_actions.0.as_mut_ptr(),
690                    fd,
691                    libc::STDIN_FILENO,
692                ))?;
693            }
694            if let Some(fd) = stdio.stdout.fd() {
695                cvt_nz(libc::posix_spawn_file_actions_adddup2(
696                    file_actions.0.as_mut_ptr(),
697                    fd,
698                    libc::STDOUT_FILENO,
699                ))?;
700            }
701            if let Some(fd) = stdio.stderr.fd() {
702                cvt_nz(libc::posix_spawn_file_actions_adddup2(
703                    file_actions.0.as_mut_ptr(),
704                    fd,
705                    libc::STDERR_FILENO,
706                ))?;
707            }
708            if let Some((f, cwd)) = addchdir {
709                cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
710            }
711
712            if let Some(pgroup) = pgroup {
713                flags |= libc::POSIX_SPAWN_SETPGROUP;
714                cvt_nz(libc::posix_spawnattr_setpgroup(attrs.0.as_mut_ptr(), pgroup))?;
715            }
716
717            // Inherit the signal mask from this process rather than resetting it (i.e. do not call
718            // posix_spawnattr_setsigmask).
719
720            // If -Zon-broken-pipe is used, don't reset SIGPIPE to SIG_DFL.
721            // If -Zon-broken-pipe is not used, reset SIGPIPE to SIG_DFL for backward compatibility.
722            //
723            // -Zon-broken-pipe is an opportunity to change the default here.
724            if !on_broken_pipe_flag_used() {
725                let mut default_set = MaybeUninit::<libc::sigset_t>::uninit();
726                cvt(sigemptyset(default_set.as_mut_ptr()))?;
727                cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGPIPE))?;
728                #[cfg(target_os = "hurd")]
729                {
730                    cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGLOST))?;
731                }
732                cvt_nz(libc::posix_spawnattr_setsigdefault(
733                    attrs.0.as_mut_ptr(),
734                    default_set.as_ptr(),
735                ))?;
736                flags |= libc::POSIX_SPAWN_SETSIGDEF;
737            }
738
739            cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
740
741            // Make sure we synchronize access to the global `environ` resource
742            let _env_lock = sys::env::env_read_lock();
743            let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::env::environ() as *const _);
744
745            #[cfg(not(target_os = "nto"))]
746            let spawn_fn = libc::posix_spawnp;
747            #[cfg(target_os = "nto")]
748            let spawn_fn = retrying_libc_posix_spawnp;
749
750            #[cfg(target_os = "linux")]
751            if self.get_create_pidfd() && PIDFD_SUPPORTED.load(Ordering::Relaxed) == SPAWN {
752                let mut pidfd: libc::c_int = -1;
753                let spawn_res = pidfd_spawnp.get().unwrap()(
754                    &mut pidfd,
755                    self.get_program_cstr().as_ptr(),
756                    file_actions.0.as_ptr(),
757                    attrs.0.as_ptr(),
758                    self.get_argv().as_ptr() as *const _,
759                    envp as *const _,
760                );
761
762                let spawn_res = cvt_nz(spawn_res);
763                if let Err(ref e) = spawn_res
764                    && e.raw_os_error() == Some(libc::ENOSYS)
765                {
766                    PIDFD_SUPPORTED.store(FORK_EXEC, Ordering::Relaxed);
767                    return Ok(None);
768                }
769                spawn_res?;
770
771                let pid = match cvt(pidfd_getpid.get().unwrap()(pidfd)) {
772                    Ok(pid) => pid,
773                    Err(e) => {
774                        // The child has been spawned and we are holding its pidfd.
775                        // But we cannot obtain its pid even though pidfd_getpid support was verified earlier.
776                        // This might happen if libc can't open procfs because the file descriptor limit has been reached.
777                        libc::close(pidfd);
778                        return Err(Error::new(
779                            e.kind(),
780                            "pidfd_spawnp succeeded but the child's PID could not be obtained",
781                        ));
782                    }
783                };
784
785                return Ok(Some(Process::new(pid, pidfd)));
786            }
787
788            // Safety: -1 indicates we don't have a pidfd.
789            let mut p = Process::new(0, -1);
790
791            let spawn_res = spawn_fn(
792                &mut p.pid,
793                self.get_program_cstr().as_ptr(),
794                file_actions.0.as_ptr(),
795                attrs.0.as_ptr(),
796                self.get_argv().as_ptr() as *const _,
797                envp as *const _,
798            );
799
800            #[cfg(target_os = "nto")]
801            let spawn_res = spawn_res?;
802
803            cvt_nz(spawn_res)?;
804            Ok(Some(p))
805        }
806    }
807
808    #[cfg(target_os = "linux")]
809    fn send_pidfd(&self, sock: &crate::sys::net::Socket) {
810        use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
811
812        use crate::io::IoSlice;
813        use crate::os::fd::RawFd;
814        use crate::sys::cvt_r;
815
816        unsafe {
817            let child_pid = libc::getpid();
818            // pidfd_open sets CLOEXEC by default
819            let pidfd = libc::syscall(libc::SYS_pidfd_open, child_pid, 0);
820
821            let fds: [c_int; 1] = [pidfd as RawFd];
822
823            const SCM_MSG_LEN: usize = size_of::<[c_int; 1]>();
824
825            #[repr(C)]
826            union Cmsg {
827                buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
828                _align: libc::cmsghdr,
829            }
830
831            let mut cmsg: Cmsg = mem::zeroed();
832
833            // 0-length message to send through the socket so we can pass along the fd
834            let mut iov = [IoSlice::new(b"")];
835            let mut msg: libc::msghdr = mem::zeroed();
836
837            msg.msg_iov = (&raw mut iov) as *mut _;
838            msg.msg_iovlen = 1;
839
840            // only attach cmsg if we successfully acquired the pidfd
841            if pidfd >= 0 {
842                msg.msg_controllen = size_of_val(&cmsg.buf) as _;
843                msg.msg_control = (&raw mut cmsg.buf) as *mut _;
844
845                let hdr = CMSG_FIRSTHDR((&raw mut msg) as *mut _);
846                (*hdr).cmsg_level = SOL_SOCKET;
847                (*hdr).cmsg_type = SCM_RIGHTS;
848                (*hdr).cmsg_len = CMSG_LEN(SCM_MSG_LEN as _) as _;
849                let data = CMSG_DATA(hdr);
850                crate::ptr::copy_nonoverlapping(
851                    fds.as_ptr().cast::<u8>(),
852                    data as *mut _,
853                    SCM_MSG_LEN,
854                );
855            }
856
857            // we send the 0-length message even if we failed to acquire the pidfd
858            // so we get a consistent SEQPACKET order
859            match cvt_r(|| libc::sendmsg(sock.as_raw(), &msg, 0)) {
860                Ok(0) => {}
861                other => rtabort!("failed to communicate with parent process. {:?}", other),
862            }
863        }
864    }
865
866    #[cfg(target_os = "linux")]
867    fn recv_pidfd(&self, sock: &crate::sys::net::Socket) -> pid_t {
868        use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
869
870        use crate::io::IoSliceMut;
871        use crate::sys::cvt_r;
872
873        unsafe {
874            const SCM_MSG_LEN: usize = size_of::<[c_int; 1]>();
875
876            #[repr(C)]
877            union Cmsg {
878                _buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
879                _align: libc::cmsghdr,
880            }
881            let mut cmsg: Cmsg = mem::zeroed();
882            // 0-length read to get the fd
883            let mut iov = [IoSliceMut::new(&mut [])];
884
885            let mut msg: libc::msghdr = mem::zeroed();
886
887            msg.msg_iov = (&raw mut iov) as *mut _;
888            msg.msg_iovlen = 1;
889            msg.msg_controllen = size_of::<Cmsg>() as _;
890            msg.msg_control = (&raw mut cmsg) as *mut _;
891
892            match cvt_r(|| libc::recvmsg(sock.as_raw(), &mut msg, libc::MSG_CMSG_CLOEXEC)) {
893                Err(_) => return -1,
894                Ok(_) => {}
895            }
896
897            let hdr = CMSG_FIRSTHDR((&raw mut msg) as *mut _);
898            if hdr.is_null()
899                || (*hdr).cmsg_level != SOL_SOCKET
900                || (*hdr).cmsg_type != SCM_RIGHTS
901                || (*hdr).cmsg_len != CMSG_LEN(SCM_MSG_LEN as _) as _
902            {
903                return -1;
904            }
905            let data = CMSG_DATA(hdr);
906
907            let mut fds = [-1 as c_int];
908
909            crate::ptr::copy_nonoverlapping(
910                data as *const _,
911                fds.as_mut_ptr().cast::<u8>(),
912                SCM_MSG_LEN,
913            );
914
915            fds[0]
916        }
917    }
918}
919
920////////////////////////////////////////////////////////////////////////////////
921// Processes
922////////////////////////////////////////////////////////////////////////////////
923
924/// The unique ID of the process (this should never be negative).
925pub struct Process {
926    pid: pid_t,
927    status: Option<ExitStatus>,
928    // On Linux, stores the pidfd created for this child.
929    // This is None if the user did not request pidfd creation,
930    // or if the pidfd could not be created for some reason
931    // (e.g. the `pidfd_open` syscall was not available).
932    #[cfg(target_os = "linux")]
933    pidfd: Option<PidFd>,
934}
935
936impl Process {
937    #[cfg(target_os = "linux")]
938    /// # Safety
939    ///
940    /// `pidfd` must either be -1 (representing no file descriptor) or a valid, exclusively owned file
941    /// descriptor (See [I/O Safety]).
942    ///
943    /// [I/O Safety]: crate::io#io-safety
944    unsafe fn new(pid: pid_t, pidfd: pid_t) -> Self {
945        use crate::os::unix::io::FromRawFd;
946        use crate::sys_common::FromInner;
947        // Safety: If `pidfd` is nonnegative, we assume it's valid and otherwise unowned.
948        let pidfd = (pidfd >= 0).then(|| PidFd::from_inner(sys::fd::FileDesc::from_raw_fd(pidfd)));
949        Process { pid, status: None, pidfd }
950    }
951
952    #[cfg(not(target_os = "linux"))]
953    unsafe fn new(pid: pid_t, _pidfd: pid_t) -> Self {
954        Process { pid, status: None }
955    }
956
957    pub fn id(&self) -> u32 {
958        self.pid as u32
959    }
960
961    pub fn kill(&mut self) -> io::Result<()> {
962        // If we've already waited on this process then the pid can be recycled
963        // and used for another process, and we probably shouldn't be killing
964        // random processes, so return Ok because the process has exited already.
965        if self.status.is_some() {
966            return Ok(());
967        }
968        #[cfg(target_os = "linux")]
969        if let Some(pid_fd) = self.pidfd.as_ref() {
970            // pidfd_send_signal predates pidfd_open. so if we were able to get an fd then sending signals will work too
971            return pid_fd.kill();
972        }
973        cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
974    }
975
976    pub fn wait(&mut self) -> io::Result<ExitStatus> {
977        use crate::sys::cvt_r;
978        if let Some(status) = self.status {
979            return Ok(status);
980        }
981        #[cfg(target_os = "linux")]
982        if let Some(pid_fd) = self.pidfd.as_ref() {
983            let status = pid_fd.wait()?;
984            self.status = Some(status);
985            return Ok(status);
986        }
987        let mut status = 0 as c_int;
988        cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
989        self.status = Some(ExitStatus::new(status));
990        Ok(ExitStatus::new(status))
991    }
992
993    pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
994        if let Some(status) = self.status {
995            return Ok(Some(status));
996        }
997        #[cfg(target_os = "linux")]
998        if let Some(pid_fd) = self.pidfd.as_ref() {
999            let status = pid_fd.try_wait()?;
1000            if let Some(status) = status {
1001                self.status = Some(status)
1002            }
1003            return Ok(status);
1004        }
1005        let mut status = 0 as c_int;
1006        let pid = cvt(unsafe { libc::waitpid(self.pid, &mut status, libc::WNOHANG) })?;
1007        if pid == 0 {
1008            Ok(None)
1009        } else {
1010            self.status = Some(ExitStatus::new(status));
1011            Ok(Some(ExitStatus::new(status)))
1012        }
1013    }
1014}
1015
1016/// Unix exit statuses
1017//
1018// This is not actually an "exit status" in Unix terminology.  Rather, it is a "wait status".
1019// See the discussion in comments and doc comments for `std::process::ExitStatus`.
1020#[derive(PartialEq, Eq, Clone, Copy, Default)]
1021pub struct ExitStatus(c_int);
1022
1023impl fmt::Debug for ExitStatus {
1024    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1025        f.debug_tuple("unix_wait_status").field(&self.0).finish()
1026    }
1027}
1028
1029impl ExitStatus {
1030    pub fn new(status: c_int) -> ExitStatus {
1031        ExitStatus(status)
1032    }
1033
1034    #[cfg(target_os = "linux")]
1035    pub fn from_waitid_siginfo(siginfo: libc::siginfo_t) -> ExitStatus {
1036        let status = unsafe { siginfo.si_status() };
1037
1038        match siginfo.si_code {
1039            libc::CLD_EXITED => ExitStatus((status & 0xff) << 8),
1040            libc::CLD_KILLED => ExitStatus(status),
1041            libc::CLD_DUMPED => ExitStatus(status | 0x80),
1042            libc::CLD_CONTINUED => ExitStatus(0xffff),
1043            libc::CLD_STOPPED | libc::CLD_TRAPPED => ExitStatus(((status & 0xff) << 8) | 0x7f),
1044            _ => unreachable!("waitid() should only return the above codes"),
1045        }
1046    }
1047
1048    fn exited(&self) -> bool {
1049        libc::WIFEXITED(self.0)
1050    }
1051
1052    pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
1053        // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is
1054        // true on all actual versions of Unix, is widely assumed, and is specified in SuS
1055        // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html. If it is not
1056        // true for a platform pretending to be Unix, the tests (our doctests, and also
1057        // unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too.
1058        match NonZero::try_from(self.0) {
1059            /* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)),
1060            /* was zero, couldn't convert */ Err(_) => Ok(()),
1061        }
1062    }
1063
1064    pub fn code(&self) -> Option<i32> {
1065        self.exited().then(|| libc::WEXITSTATUS(self.0))
1066    }
1067
1068    pub fn signal(&self) -> Option<i32> {
1069        libc::WIFSIGNALED(self.0).then(|| libc::WTERMSIG(self.0))
1070    }
1071
1072    pub fn core_dumped(&self) -> bool {
1073        libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
1074    }
1075
1076    pub fn stopped_signal(&self) -> Option<i32> {
1077        libc::WIFSTOPPED(self.0).then(|| libc::WSTOPSIG(self.0))
1078    }
1079
1080    pub fn continued(&self) -> bool {
1081        libc::WIFCONTINUED(self.0)
1082    }
1083
1084    pub fn into_raw(&self) -> c_int {
1085        self.0
1086    }
1087}
1088
1089/// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
1090impl From<c_int> for ExitStatus {
1091    fn from(a: c_int) -> ExitStatus {
1092        ExitStatus(a)
1093    }
1094}
1095
1096/// Converts a signal number to a readable, searchable name.
1097///
1098/// This string should be displayed right after the signal number.
1099/// If a signal is unrecognized, it returns the empty string, so that
1100/// you just get the number like "0". If it is recognized, you'll get
1101/// something like "9 (SIGKILL)".
1102fn signal_string(signal: i32) -> &'static str {
1103    match signal {
1104        libc::SIGHUP => " (SIGHUP)",
1105        libc::SIGINT => " (SIGINT)",
1106        libc::SIGQUIT => " (SIGQUIT)",
1107        libc::SIGILL => " (SIGILL)",
1108        libc::SIGTRAP => " (SIGTRAP)",
1109        libc::SIGABRT => " (SIGABRT)",
1110        #[cfg(not(target_os = "l4re"))]
1111        libc::SIGBUS => " (SIGBUS)",
1112        libc::SIGFPE => " (SIGFPE)",
1113        libc::SIGKILL => " (SIGKILL)",
1114        #[cfg(not(target_os = "l4re"))]
1115        libc::SIGUSR1 => " (SIGUSR1)",
1116        libc::SIGSEGV => " (SIGSEGV)",
1117        #[cfg(not(target_os = "l4re"))]
1118        libc::SIGUSR2 => " (SIGUSR2)",
1119        libc::SIGPIPE => " (SIGPIPE)",
1120        libc::SIGALRM => " (SIGALRM)",
1121        libc::SIGTERM => " (SIGTERM)",
1122        #[cfg(not(target_os = "l4re"))]
1123        libc::SIGCHLD => " (SIGCHLD)",
1124        #[cfg(not(target_os = "l4re"))]
1125        libc::SIGCONT => " (SIGCONT)",
1126        #[cfg(not(target_os = "l4re"))]
1127        libc::SIGSTOP => " (SIGSTOP)",
1128        #[cfg(not(target_os = "l4re"))]
1129        libc::SIGTSTP => " (SIGTSTP)",
1130        #[cfg(not(target_os = "l4re"))]
1131        libc::SIGTTIN => " (SIGTTIN)",
1132        #[cfg(not(target_os = "l4re"))]
1133        libc::SIGTTOU => " (SIGTTOU)",
1134        #[cfg(not(target_os = "l4re"))]
1135        libc::SIGURG => " (SIGURG)",
1136        #[cfg(not(target_os = "l4re"))]
1137        libc::SIGXCPU => " (SIGXCPU)",
1138        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1139        libc::SIGXFSZ => " (SIGXFSZ)",
1140        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1141        libc::SIGVTALRM => " (SIGVTALRM)",
1142        #[cfg(not(target_os = "l4re"))]
1143        libc::SIGPROF => " (SIGPROF)",
1144        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
1145        libc::SIGWINCH => " (SIGWINCH)",
1146        #[cfg(not(any(target_os = "haiku", target_os = "l4re")))]
1147        libc::SIGIO => " (SIGIO)",
1148        #[cfg(target_os = "haiku")]
1149        libc::SIGPOLL => " (SIGPOLL)",
1150        #[cfg(not(target_os = "l4re"))]
1151        libc::SIGSYS => " (SIGSYS)",
1152        // For information on Linux signals, run `man 7 signal`
1153        #[cfg(all(
1154            target_os = "linux",
1155            any(
1156                target_arch = "x86_64",
1157                target_arch = "x86",
1158                target_arch = "arm",
1159                target_arch = "aarch64"
1160            )
1161        ))]
1162        libc::SIGSTKFLT => " (SIGSTKFLT)",
1163        #[cfg(any(target_os = "linux", target_os = "nto", target_os = "cygwin"))]
1164        libc::SIGPWR => " (SIGPWR)",
1165        #[cfg(any(
1166            target_os = "freebsd",
1167            target_os = "netbsd",
1168            target_os = "openbsd",
1169            target_os = "dragonfly",
1170            target_os = "nto",
1171            target_vendor = "apple",
1172            target_os = "cygwin",
1173        ))]
1174        libc::SIGEMT => " (SIGEMT)",
1175        #[cfg(any(
1176            target_os = "freebsd",
1177            target_os = "netbsd",
1178            target_os = "openbsd",
1179            target_os = "dragonfly",
1180            target_vendor = "apple",
1181        ))]
1182        libc::SIGINFO => " (SIGINFO)",
1183        #[cfg(target_os = "hurd")]
1184        libc::SIGLOST => " (SIGLOST)",
1185        #[cfg(target_os = "freebsd")]
1186        libc::SIGTHR => " (SIGTHR)",
1187        #[cfg(target_os = "freebsd")]
1188        libc::SIGLIBRT => " (SIGLIBRT)",
1189        _ => "",
1190    }
1191}
1192
1193impl fmt::Display for ExitStatus {
1194    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1195        if let Some(code) = self.code() {
1196            write!(f, "exit status: {code}")
1197        } else if let Some(signal) = self.signal() {
1198            let signal_string = signal_string(signal);
1199            if self.core_dumped() {
1200                write!(f, "signal: {signal}{signal_string} (core dumped)")
1201            } else {
1202                write!(f, "signal: {signal}{signal_string}")
1203            }
1204        } else if let Some(signal) = self.stopped_signal() {
1205            let signal_string = signal_string(signal);
1206            write!(f, "stopped (not terminated) by signal: {signal}{signal_string}")
1207        } else if self.continued() {
1208            write!(f, "continued (WIFCONTINUED)")
1209        } else {
1210            write!(f, "unrecognised wait status: {} {:#x}", self.0, self.0)
1211        }
1212    }
1213}
1214
1215#[derive(PartialEq, Eq, Clone, Copy)]
1216pub struct ExitStatusError(NonZero<c_int>);
1217
1218impl Into<ExitStatus> for ExitStatusError {
1219    fn into(self) -> ExitStatus {
1220        ExitStatus(self.0.into())
1221    }
1222}
1223
1224impl fmt::Debug for ExitStatusError {
1225    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1226        f.debug_tuple("unix_wait_status").field(&self.0).finish()
1227    }
1228}
1229
1230impl ExitStatusError {
1231    pub fn code(self) -> Option<NonZero<i32>> {
1232        ExitStatus(self.0.into()).code().map(|st| st.try_into().unwrap())
1233    }
1234}
1235
1236#[cfg(target_os = "linux")]
1237mod linux_child_ext {
1238    use crate::io::ErrorKind;
1239    use crate::os::linux::process as os;
1240    use crate::sys::pal::linux::pidfd as imp;
1241    use crate::sys_common::FromInner;
1242    use crate::{io, mem};
1243
1244    #[unstable(feature = "linux_pidfd", issue = "82971")]
1245    impl crate::os::linux::process::ChildExt for crate::process::Child {
1246        fn pidfd(&self) -> io::Result<&os::PidFd> {
1247            self.handle
1248                .pidfd
1249                .as_ref()
1250                // SAFETY: The os type is a transparent wrapper, therefore we can transmute references
1251                .map(|fd| unsafe { mem::transmute::<&imp::PidFd, &os::PidFd>(fd) })
1252                .ok_or_else(|| io::const_error!(ErrorKind::Uncategorized, "no pidfd was created."))
1253        }
1254
1255        fn into_pidfd(mut self) -> Result<os::PidFd, Self> {
1256            self.handle
1257                .pidfd
1258                .take()
1259                .map(|fd| <os::PidFd as FromInner<imp::PidFd>>::from_inner(fd))
1260                .ok_or_else(|| self)
1261        }
1262    }
1263}
1264
1265#[cfg(test)]
1266mod tests;
1267
1268// See [`unsupported_wait_status::compare_with_linux`];
1269#[cfg(all(test, target_os = "linux"))]
1270#[path = "unsupported/wait_status.rs"]
1271mod unsupported_wait_status;
std/sys/process/unix/unix.rs

std/sys/process/unix/
unix.rs
