1 use crate::convert::TryInto;
3 use crate::io::{self, Error, ErrorKind};
7 use crate::sys::process::process_common::*;
9 #[cfg(target_os = "vxworks")]
10 use libc::RTP_ID as pid_t;
12 #[cfg(not(target_os = "vxworks"))]
13 use libc::{c_int, gid_t, pid_t, uid_t};
15 ////////////////////////////////////////////////////////////////////////////////
17 ////////////////////////////////////////////////////////////////////////////////
24 ) -> io::Result<(Process, StdioPipes)> {
25 const CLOEXEC_MSG_FOOTER: [u8; 4] = *b"NOEX";
27 let envp = self.capture_env();
30 return Err(io::Error::new(ErrorKind::InvalidInput, "nul byte found in provided data"));
33 let (ours, theirs) = self.setup_io(default, needs_stdin)?;
35 if let Some(ret) = self.posix_spawn(&theirs, envp.as_ref())? {
36 return Ok((ret, ours));
39 let (input, output) = sys::pipe::anon_pipe()?;
41 // Whatever happens after the fork is almost for sure going to touch or
42 // look at the environment in one way or another (PATH in `execvp` or
43 // accessing the `environ` pointer ourselves). Make sure no other thread
44 // is accessing the environment when we do the fork itself.
46 // Note that as soon as we're done with the fork there's no need to hold
47 // a lock any more because the parent won't do anything and the child is
48 // in its own process.
50 let _env_lock = sys::os::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());
81 let mut p = Process { pid, status: None };
83 let mut bytes = [0; 8];
85 // loop to handle EINTR
87 match input.read(&mut bytes) {
88 Ok(0) => return Ok((p, ours)),
90 let (errno, footer) = bytes.split_at(4);
92 CLOEXEC_MSG_FOOTER, footer,
93 "Validation on the CLOEXEC pipe failed: {:?}",
96 let errno = i32::from_be_bytes(errno.try_into().unwrap());
97 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
98 return Err(Error::from_raw_os_error(errno));
100 Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
102 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
103 panic!("the CLOEXEC pipe failed: {:?}", e)
106 // pipe I/O up to PIPE_BUF bytes should be atomic
107 assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
108 panic!("short read on the CLOEXEC pipe")
114 pub fn exec(&mut self, default: Stdio) -> io::Error {
115 let envp = self.capture_env();
118 return io::Error::new(ErrorKind::InvalidInput, "nul byte found in provided data");
121 match self.setup_io(default, true) {
124 // Similar to when forking, we want to ensure that access to
125 // the environment is synchronized, so make sure to grab the
126 // environment lock before we try to exec.
127 let _lock = sys::os::env_lock();
129 let Err(e) = self.do_exec(theirs, envp.as_ref());
137 // And at this point we've reached a special time in the life of the
138 // child. The child must now be considered hamstrung and unable to
139 // do anything other than syscalls really. Consider the following
142 // 1. Thread A of process 1 grabs the malloc() mutex
143 // 2. Thread B of process 1 forks(), creating thread C
144 // 3. Thread C of process 2 then attempts to malloc()
145 // 4. The memory of process 2 is the same as the memory of
146 // process 1, so the mutex is locked.
148 // This situation looks a lot like deadlock, right? It turns out
149 // that this is what pthread_atfork() takes care of, which is
150 // presumably implemented across platforms. The first thing that
151 // threads to *before* forking is to do things like grab the malloc
152 // mutex, and then after the fork they unlock it.
154 // Despite this information, libnative's spawn has been witnessed to
155 // deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
156 // all collected backtraces point at malloc/free traffic in the
157 // child spawned process.
159 // For this reason, the block of code below should contain 0
160 // invocations of either malloc of free (or their related friends).
162 // As an example of not having malloc/free traffic, we don't close
163 // this file descriptor by dropping the FileDesc (which contains an
164 // allocation). Instead we just close it manually. This will never
165 // have the drop glue anyway because this code never returns (the
166 // child will either exec() or invoke libc::exit)
170 maybe_envp: Option<&CStringArray>,
171 ) -> Result<!, io::Error> {
172 use crate::sys::{self, cvt_r};
174 if let Some(fd) = stdio.stdin.fd() {
175 cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
177 if let Some(fd) = stdio.stdout.fd() {
178 cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
180 if let Some(fd) = stdio.stderr.fd() {
181 cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
184 #[cfg(not(target_os = "l4re"))]
186 if let Some(_g) = self.get_groups() {
187 //FIXME: Redox kernel does not support setgroups yet
188 #[cfg(not(target_os = "redox"))]
189 cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
191 if let Some(u) = self.get_gid() {
192 cvt(libc::setgid(u as gid_t))?;
194 if let Some(u) = self.get_uid() {
195 // When dropping privileges from root, the `setgroups` call
196 // will remove any extraneous groups. We only drop groups
197 // if the current uid is 0 and we weren't given an explicit
198 // set of groups. If we don't call this, then even though our
199 // uid has dropped, we may still have groups that enable us to
200 // do super-user things.
201 //FIXME: Redox kernel does not support setgroups yet
202 #[cfg(not(target_os = "redox"))]
203 if libc::getuid() == 0 && self.get_groups().is_none() {
204 cvt(libc::setgroups(0, ptr::null()))?;
206 cvt(libc::setuid(u as uid_t))?;
209 if let Some(ref cwd) = *self.get_cwd() {
210 cvt(libc::chdir(cwd.as_ptr()))?;
213 // emscripten has no signal support.
214 #[cfg(not(target_os = "emscripten"))]
216 use crate::mem::MaybeUninit;
217 // Reset signal handling so the child process starts in a
218 // standardized state. libstd ignores SIGPIPE, and signal-handling
219 // libraries often set a mask. Child processes inherit ignored
220 // signals and the signal mask from their parent, but most
221 // UNIX programs do not reset these things on their own, so we
222 // need to clean things up now to avoid confusing the program
223 // we're about to run.
224 let mut set = MaybeUninit::<libc::sigset_t>::uninit();
225 cvt(sigemptyset(set.as_mut_ptr()))?;
226 cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), ptr::null_mut()))?;
227 let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL);
228 if ret == libc::SIG_ERR {
229 return Err(io::Error::last_os_error());
233 for callback in self.get_closures().iter_mut() {
237 // Although we're performing an exec here we may also return with an
238 // error from this function (without actually exec'ing) in which case we
239 // want to be sure to restore the global environment back to what it
240 // once was, ensuring that our temporary override, when free'd, doesn't
241 // corrupt our process's environment.
242 let mut _reset = None;
243 if let Some(envp) = maybe_envp {
244 struct Reset(*const *const libc::c_char);
246 impl Drop for Reset {
249 *sys::os::environ() = self.0;
254 _reset = Some(Reset(*sys::os::environ()));
255 *sys::os::environ() = envp.as_ptr();
258 libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr());
259 Err(io::Error::last_os_error())
264 target_os = "freebsd",
265 all(target_os = "linux", target_env = "gnu"),
266 all(target_os = "linux", target_env = "musl"),
271 _: Option<&CStringArray>,
272 ) -> io::Result<Option<Process>> {
276 // Only support platforms for which posix_spawn() can return ENOENT
280 target_os = "freebsd",
281 all(target_os = "linux", target_env = "gnu"),
282 all(target_os = "linux", target_env = "musl"),
287 envp: Option<&CStringArray>,
288 ) -> io::Result<Option<Process>> {
289 use crate::mem::MaybeUninit;
290 use crate::sys::{self, cvt_nz};
292 if self.get_gid().is_some()
293 || self.get_uid().is_some()
294 || (self.env_saw_path() && !self.program_is_path())
295 || !self.get_closures().is_empty()
296 || self.get_groups().is_some()
301 // Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
302 #[cfg(all(target_os = "linux", target_env = "gnu"))]
304 if let Some(version) = sys::os::glibc_version() {
305 if version < (2, 24) {
313 // Solaris, glibc 2.29+, and musl 1.24+ can set a new working directory,
314 // and maybe others will gain this non-POSIX function too. We'll check
315 // for this weak symbol as soon as it's needed, so we can return early
316 // otherwise to do a manual chdir before exec.
318 fn posix_spawn_file_actions_addchdir_np(
319 *mut libc::posix_spawn_file_actions_t,
323 let addchdir = match self.get_cwd() {
325 if cfg!(target_os = "macos") {
326 // There is a bug in macOS where a relative executable
327 // path like "../myprogram" will cause `posix_spawn` to
328 // successfully launch the program, but erroneously return
329 // ENOENT when used with posix_spawn_file_actions_addchdir_np
330 // which was introduced in macOS 10.15.
333 match posix_spawn_file_actions_addchdir_np.get() {
334 Some(f) => Some((f, cwd)),
335 None => return Ok(None),
341 let mut p = Process { pid: 0, status: None };
343 struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
345 impl Drop for PosixSpawnFileActions<'_> {
348 libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
353 struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
355 impl Drop for PosixSpawnattr<'_> {
358 libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
364 let mut attrs = MaybeUninit::uninit();
365 cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
366 let attrs = PosixSpawnattr(&mut attrs);
368 let mut file_actions = MaybeUninit::uninit();
369 cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
370 let file_actions = PosixSpawnFileActions(&mut file_actions);
372 if let Some(fd) = stdio.stdin.fd() {
373 cvt_nz(libc::posix_spawn_file_actions_adddup2(
374 file_actions.0.as_mut_ptr(),
379 if let Some(fd) = stdio.stdout.fd() {
380 cvt_nz(libc::posix_spawn_file_actions_adddup2(
381 file_actions.0.as_mut_ptr(),
386 if let Some(fd) = stdio.stderr.fd() {
387 cvt_nz(libc::posix_spawn_file_actions_adddup2(
388 file_actions.0.as_mut_ptr(),
393 if let Some((f, cwd)) = addchdir {
394 cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
397 let mut set = MaybeUninit::<libc::sigset_t>::uninit();
398 cvt(sigemptyset(set.as_mut_ptr()))?;
399 cvt_nz(libc::posix_spawnattr_setsigmask(attrs.0.as_mut_ptr(), set.as_ptr()))?;
400 cvt(sigaddset(set.as_mut_ptr(), libc::SIGPIPE))?;
401 cvt_nz(libc::posix_spawnattr_setsigdefault(attrs.0.as_mut_ptr(), set.as_ptr()))?;
403 let flags = libc::POSIX_SPAWN_SETSIGDEF | libc::POSIX_SPAWN_SETSIGMASK;
404 cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
406 // Make sure we synchronize access to the global `environ` resource
407 let _env_lock = sys::os::env_lock();
408 let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::os::environ() as *const _);
409 cvt_nz(libc::posix_spawnp(
411 self.get_program_cstr().as_ptr(),
412 file_actions.0.as_ptr(),
414 self.get_argv().as_ptr() as *const _,
422 ////////////////////////////////////////////////////////////////////////////////
424 ////////////////////////////////////////////////////////////////////////////////
426 /// The unique ID of the process (this should never be negative).
429 status: Option<ExitStatus>,
433 pub fn id(&self) -> u32 {
437 pub fn kill(&mut self) -> io::Result<()> {
438 // If we've already waited on this process then the pid can be recycled
439 // and used for another process, and we probably shouldn't be killing
440 // random processes, so just return an error.
441 if self.status.is_some() {
443 ErrorKind::InvalidInput,
444 "invalid argument: can't kill an exited process",
447 cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
451 pub fn wait(&mut self) -> io::Result<ExitStatus> {
452 use crate::sys::cvt_r;
453 if let Some(status) = self.status {
456 let mut status = 0 as c_int;
457 cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
458 self.status = Some(ExitStatus::new(status));
459 Ok(ExitStatus::new(status))
462 pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
463 if let Some(status) = self.status {
464 return Ok(Some(status));
466 let mut status = 0 as c_int;
467 let pid = cvt(unsafe { libc::waitpid(self.pid, &mut status, libc::WNOHANG) })?;
471 self.status = Some(ExitStatus::new(status));
472 Ok(Some(ExitStatus::new(status)))
477 /// Unix exit statuses
478 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
479 pub struct ExitStatus(c_int);
482 pub fn new(status: c_int) -> ExitStatus {
486 fn exited(&self) -> bool {
487 libc::WIFEXITED(self.0)
490 pub fn success(&self) -> bool {
491 self.code() == Some(0)
494 pub fn code(&self) -> Option<i32> {
495 if self.exited() { Some(libc::WEXITSTATUS(self.0)) } else { None }
498 pub fn signal(&self) -> Option<i32> {
499 if libc::WIFSIGNALED(self.0) { Some(libc::WTERMSIG(self.0)) } else { None }
502 pub fn core_dumped(&self) -> bool {
503 libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
506 pub fn stopped_signal(&self) -> Option<i32> {
507 if libc::WIFSTOPPED(self.0) { Some(libc::WSTOPSIG(self.0)) } else { None }
510 pub fn continued(&self) -> bool {
511 libc::WIFCONTINUED(self.0)
514 pub fn into_raw(&self) -> c_int {
519 /// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
520 impl From<c_int> for ExitStatus {
521 fn from(a: c_int) -> ExitStatus {
526 impl fmt::Display for ExitStatus {
527 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
528 if let Some(code) = self.code() {
529 write!(f, "exit code: {}", code)
530 } else if let Some(signal) = self.signal() {
531 if self.core_dumped() {
532 write!(f, "signal: {} (core dumped)", signal)
534 write!(f, "signal: {}", signal)
536 } else if let Some(signal) = self.stopped_signal() {
537 write!(f, "stopped (not terminated) by signal: {}", signal)
538 } else if self.continued() {
539 write!(f, "continued (WIFCONTINUED)")
541 write!(f, "unrecognised wait status: {} {:#x}", self.0, self.0)
547 #[path = "process_unix/tests.rs"]