1 use crate::convert::TryInto;
3 use crate::io::{self, Error, ErrorKind};
8 use crate::sys::process::process_common::*;
10 #[cfg(target_os = "vxworks")]
11 use libc::RTP_ID as pid_t;
13 #[cfg(not(target_os = "vxworks"))]
14 use libc::{c_int, gid_t, pid_t, uid_t};
16 ////////////////////////////////////////////////////////////////////////////////
18 ////////////////////////////////////////////////////////////////////////////////
25 ) -> io::Result<(Process, StdioPipes)> {
26 const CLOEXEC_MSG_FOOTER: [u8; 4] = *b"NOEX";
28 let envp = self.capture_env();
31 return Err(io::Error::new(ErrorKind::InvalidInput, "nul byte found in provided data"));
34 let (ours, theirs) = self.setup_io(default, needs_stdin)?;
36 if let Some(ret) = self.posix_spawn(&theirs, envp.as_ref())? {
37 return Ok((ret, ours));
40 let (input, output) = sys::pipe::anon_pipe()?;
42 // Whatever happens after the fork is almost for sure going to touch or
43 // look at the environment in one way or another (PATH in `execvp` or
44 // accessing the `environ` pointer ourselves). Make sure no other thread
45 // is accessing the environment when we do the fork itself.
47 // Note that as soon as we're done with the fork there's no need to hold
48 // a lock any more because the parent won't do anything and the child is
49 // in its own process. Thus the parent drops the lock guard while the child
50 // forgets it to avoid unlocking it on a new thread, which would be invalid.
51 let (env_lock, result) = unsafe { (sys::os::env_read_lock(), cvt(libc::fork())?) };
56 mem::forget(env_lock);
58 let Err(err) = self.do_exec(theirs, envp.as_ref());
59 let errno = err.raw_os_error().unwrap_or(libc::EINVAL) as u32;
60 let errno = errno.to_be_bytes();
66 CLOEXEC_MSG_FOOTER[0],
67 CLOEXEC_MSG_FOOTER[1],
68 CLOEXEC_MSG_FOOTER[2],
69 CLOEXEC_MSG_FOOTER[3],
71 // pipe I/O up to PIPE_BUF bytes should be atomic, and then
72 // we want to be sure we *don't* run at_exit destructors as
73 // we're being torn down regardless
74 rtassert!(output.write(&bytes).is_ok());
84 let mut p = Process { pid, status: None };
86 let mut bytes = [0; 8];
88 // loop to handle EINTR
90 match input.read(&mut bytes) {
91 Ok(0) => return Ok((p, ours)),
93 let (errno, footer) = bytes.split_at(4);
95 CLOEXEC_MSG_FOOTER, footer,
96 "Validation on the CLOEXEC pipe failed: {:?}",
99 let errno = i32::from_be_bytes(errno.try_into().unwrap());
100 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
101 return Err(Error::from_raw_os_error(errno));
103 Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
105 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
106 panic!("the CLOEXEC pipe failed: {:?}", e)
109 // pipe I/O up to PIPE_BUF bytes should be atomic
110 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
111 panic!("short read on the CLOEXEC pipe")
117 pub fn exec(&mut self, default: Stdio) -> io::Error {
118 let envp = self.capture_env();
121 return io::Error::new(ErrorKind::InvalidInput, "nul byte found in provided data");
124 match self.setup_io(default, true) {
127 // Similar to when forking, we want to ensure that access to
128 // the environment is synchronized, so make sure to grab the
129 // environment lock before we try to exec.
130 let _lock = sys::os::env_read_lock();
132 let Err(e) = self.do_exec(theirs, envp.as_ref());
140 // And at this point we've reached a special time in the life of the
141 // child. The child must now be considered hamstrung and unable to
142 // do anything other than syscalls really. Consider the following
145 // 1. Thread A of process 1 grabs the malloc() mutex
146 // 2. Thread B of process 1 forks(), creating thread C
147 // 3. Thread C of process 2 then attempts to malloc()
148 // 4. The memory of process 2 is the same as the memory of
149 // process 1, so the mutex is locked.
151 // This situation looks a lot like deadlock, right? It turns out
152 // that this is what pthread_atfork() takes care of, which is
153 // presumably implemented across platforms. The first thing that
154 // threads to *before* forking is to do things like grab the malloc
155 // mutex, and then after the fork they unlock it.
157 // Despite this information, libnative's spawn has been witnessed to
158 // deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
159 // all collected backtraces point at malloc/free traffic in the
160 // child spawned process.
162 // For this reason, the block of code below should contain 0
163 // invocations of either malloc of free (or their related friends).
165 // As an example of not having malloc/free traffic, we don't close
166 // this file descriptor by dropping the FileDesc (which contains an
167 // allocation). Instead we just close it manually. This will never
168 // have the drop glue anyway because this code never returns (the
169 // child will either exec() or invoke libc::exit)
173 maybe_envp: Option<&CStringArray>,
174 ) -> Result<!, io::Error> {
175 use crate::sys::{self, cvt_r};
177 if let Some(fd) = stdio.stdin.fd() {
178 cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
180 if let Some(fd) = stdio.stdout.fd() {
181 cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
183 if let Some(fd) = stdio.stderr.fd() {
184 cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
187 #[cfg(not(target_os = "l4re"))]
189 if let Some(_g) = self.get_groups() {
190 //FIXME: Redox kernel does not support setgroups yet
191 #[cfg(not(target_os = "redox"))]
192 cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
194 if let Some(u) = self.get_gid() {
195 cvt(libc::setgid(u as gid_t))?;
197 if let Some(u) = self.get_uid() {
198 // When dropping privileges from root, the `setgroups` call
199 // will remove any extraneous groups. We only drop groups
200 // if the current uid is 0 and we weren't given an explicit
201 // set of groups. If we don't call this, then even though our
202 // uid has dropped, we may still have groups that enable us to
203 // do super-user things.
204 //FIXME: Redox kernel does not support setgroups yet
205 #[cfg(not(target_os = "redox"))]
206 if libc::getuid() == 0 && self.get_groups().is_none() {
207 cvt(libc::setgroups(0, ptr::null()))?;
209 cvt(libc::setuid(u as uid_t))?;
212 if let Some(ref cwd) = *self.get_cwd() {
213 cvt(libc::chdir(cwd.as_ptr()))?;
216 // emscripten has no signal support.
217 #[cfg(not(target_os = "emscripten"))]
219 use crate::mem::MaybeUninit;
220 // Reset signal handling so the child process starts in a
221 // standardized state. libstd ignores SIGPIPE, and signal-handling
222 // libraries often set a mask. Child processes inherit ignored
223 // signals and the signal mask from their parent, but most
224 // UNIX programs do not reset these things on their own, so we
225 // need to clean things up now to avoid confusing the program
226 // we're about to run.
227 let mut set = MaybeUninit::<libc::sigset_t>::uninit();
228 cvt(sigemptyset(set.as_mut_ptr()))?;
229 cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), ptr::null_mut()))?;
230 let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL);
231 if ret == libc::SIG_ERR {
232 return Err(io::Error::last_os_error());
236 for callback in self.get_closures().iter_mut() {
240 // Although we're performing an exec here we may also return with an
241 // error from this function (without actually exec'ing) in which case we
242 // want to be sure to restore the global environment back to what it
243 // once was, ensuring that our temporary override, when free'd, doesn't
244 // corrupt our process's environment.
245 let mut _reset = None;
246 if let Some(envp) = maybe_envp {
247 struct Reset(*const *const libc::c_char);
249 impl Drop for Reset {
252 *sys::os::environ() = self.0;
257 _reset = Some(Reset(*sys::os::environ()));
258 *sys::os::environ() = envp.as_ptr();
261 libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr());
262 Err(io::Error::last_os_error())
267 target_os = "freebsd",
268 all(target_os = "linux", target_env = "gnu"),
269 all(target_os = "linux", target_env = "musl"),
274 _: Option<&CStringArray>,
275 ) -> io::Result<Option<Process>> {
279 // Only support platforms for which posix_spawn() can return ENOENT
283 target_os = "freebsd",
284 all(target_os = "linux", target_env = "gnu"),
285 all(target_os = "linux", target_env = "musl"),
290 envp: Option<&CStringArray>,
291 ) -> io::Result<Option<Process>> {
292 use crate::mem::MaybeUninit;
293 use crate::sys::{self, cvt_nz};
295 if self.get_gid().is_some()
296 || self.get_uid().is_some()
297 || (self.env_saw_path() && !self.program_is_path())
298 || !self.get_closures().is_empty()
299 || self.get_groups().is_some()
304 // Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
305 #[cfg(all(target_os = "linux", target_env = "gnu"))]
307 if let Some(version) = sys::os::glibc_version() {
308 if version < (2, 24) {
316 // Solaris, glibc 2.29+, and musl 1.24+ can set a new working directory,
317 // and maybe others will gain this non-POSIX function too. We'll check
318 // for this weak symbol as soon as it's needed, so we can return early
319 // otherwise to do a manual chdir before exec.
321 fn posix_spawn_file_actions_addchdir_np(
322 *mut libc::posix_spawn_file_actions_t,
326 let addchdir = match self.get_cwd() {
328 if cfg!(target_os = "macos") {
329 // There is a bug in macOS where a relative executable
330 // path like "../myprogram" will cause `posix_spawn` to
331 // successfully launch the program, but erroneously return
332 // ENOENT when used with posix_spawn_file_actions_addchdir_np
333 // which was introduced in macOS 10.15.
336 match posix_spawn_file_actions_addchdir_np.get() {
337 Some(f) => Some((f, cwd)),
338 None => return Ok(None),
344 let mut p = Process { pid: 0, status: None };
346 struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
348 impl Drop for PosixSpawnFileActions<'_> {
351 libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
356 struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
358 impl Drop for PosixSpawnattr<'_> {
361 libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
367 let mut attrs = MaybeUninit::uninit();
368 cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
369 let attrs = PosixSpawnattr(&mut attrs);
371 let mut file_actions = MaybeUninit::uninit();
372 cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
373 let file_actions = PosixSpawnFileActions(&mut file_actions);
375 if let Some(fd) = stdio.stdin.fd() {
376 cvt_nz(libc::posix_spawn_file_actions_adddup2(
377 file_actions.0.as_mut_ptr(),
382 if let Some(fd) = stdio.stdout.fd() {
383 cvt_nz(libc::posix_spawn_file_actions_adddup2(
384 file_actions.0.as_mut_ptr(),
389 if let Some(fd) = stdio.stderr.fd() {
390 cvt_nz(libc::posix_spawn_file_actions_adddup2(
391 file_actions.0.as_mut_ptr(),
396 if let Some((f, cwd)) = addchdir {
397 cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
400 let mut set = MaybeUninit::<libc::sigset_t>::uninit();
401 cvt(sigemptyset(set.as_mut_ptr()))?;
402 cvt_nz(libc::posix_spawnattr_setsigmask(attrs.0.as_mut_ptr(), set.as_ptr()))?;
403 cvt(sigaddset(set.as_mut_ptr(), libc::SIGPIPE))?;
404 cvt_nz(libc::posix_spawnattr_setsigdefault(attrs.0.as_mut_ptr(), set.as_ptr()))?;
406 let flags = libc::POSIX_SPAWN_SETSIGDEF | libc::POSIX_SPAWN_SETSIGMASK;
407 cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
409 // Make sure we synchronize access to the global `environ` resource
410 let _env_lock = sys::os::env_read_lock();
411 let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::os::environ() as *const _);
412 cvt_nz(libc::posix_spawnp(
414 self.get_program_cstr().as_ptr(),
415 file_actions.0.as_ptr(),
417 self.get_argv().as_ptr() as *const _,
425 ////////////////////////////////////////////////////////////////////////////////
427 ////////////////////////////////////////////////////////////////////////////////
429 /// The unique ID of the process (this should never be negative).
432 status: Option<ExitStatus>,
436 pub fn id(&self) -> u32 {
440 pub fn kill(&mut self) -> io::Result<()> {
441 // If we've already waited on this process then the pid can be recycled
442 // and used for another process, and we probably shouldn't be killing
443 // random processes, so just return an error.
444 if self.status.is_some() {
446 ErrorKind::InvalidInput,
447 "invalid argument: can't kill an exited process",
450 cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
454 pub fn wait(&mut self) -> io::Result<ExitStatus> {
455 use crate::sys::cvt_r;
456 if let Some(status) = self.status {
459 let mut status = 0 as c_int;
460 cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
461 self.status = Some(ExitStatus::new(status));
462 Ok(ExitStatus::new(status))
465 pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
466 if let Some(status) = self.status {
467 return Ok(Some(status));
469 let mut status = 0 as c_int;
470 let pid = cvt(unsafe { libc::waitpid(self.pid, &mut status, libc::WNOHANG) })?;
474 self.status = Some(ExitStatus::new(status));
475 Ok(Some(ExitStatus::new(status)))
480 /// Unix exit statuses
481 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
482 pub struct ExitStatus(c_int);
485 pub fn new(status: c_int) -> ExitStatus {
489 fn exited(&self) -> bool {
490 libc::WIFEXITED(self.0)
493 pub fn success(&self) -> bool {
494 self.code() == Some(0)
497 pub fn code(&self) -> Option<i32> {
498 if self.exited() { Some(libc::WEXITSTATUS(self.0)) } else { None }
501 pub fn signal(&self) -> Option<i32> {
502 if libc::WIFSIGNALED(self.0) { Some(libc::WTERMSIG(self.0)) } else { None }
505 pub fn core_dumped(&self) -> bool {
506 libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
509 pub fn stopped_signal(&self) -> Option<i32> {
510 if libc::WIFSTOPPED(self.0) { Some(libc::WSTOPSIG(self.0)) } else { None }
513 pub fn continued(&self) -> bool {
514 libc::WIFCONTINUED(self.0)
517 pub fn into_raw(&self) -> c_int {
522 /// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
523 impl From<c_int> for ExitStatus {
524 fn from(a: c_int) -> ExitStatus {
529 impl fmt::Display for ExitStatus {
530 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
531 if let Some(code) = self.code() {
532 write!(f, "exit code: {}", code)
533 } else if let Some(signal) = self.signal() {
534 if self.core_dumped() {
535 write!(f, "signal: {} (core dumped)", signal)
537 write!(f, "signal: {}", signal)
539 } else if let Some(signal) = self.stopped_signal() {
540 write!(f, "stopped (not terminated) by signal: {}", signal)
541 } else if self.continued() {
542 write!(f, "continued (WIFCONTINUED)")
544 write!(f, "unrecognised wait status: {} {:#x}", self.0, self.0)
550 #[path = "process_unix/tests.rs"]