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rust/library/std/src/sys/unix/process/process_unix.rs

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use crate::fmt;
use crate::io::{self, Error, ErrorKind};
use crate::mem;
use crate::num::NonZeroI32;
use crate::sys;
use crate::sys::cvt;
use crate::sys::process::process_common::*;
use core::ffi::NonZero_c_int;
#[cfg(target_os = "linux")]
use crate::os::linux::process::PidFd;
#[cfg(target_os = "linux")]
use crate::os::unix::io::AsRawFd;
#[cfg(any(
target_os = "macos",
target_os = "watchos",
target_os = "tvos",
target_os = "freebsd",
all(target_os = "linux", target_env = "gnu"),
all(target_os = "linux", target_env = "musl"),
target_os = "nto",
))]
use crate::sys::weak::weak;
#[cfg(target_os = "vxworks")]
use libc::RTP_ID as pid_t;
#[cfg(not(target_os = "vxworks"))]
use libc::{c_int, pid_t};
#[cfg(not(any(
target_os = "vxworks",
target_os = "l4re",
target_os = "tvos",
target_os = "watchos",
)))]
use libc::{gid_t, uid_t};
cfg_if::cfg_if! {
if #[cfg(all(target_os = "nto", target_env = "nto71"))] {
use crate::thread;
use libc::{c_char, posix_spawn_file_actions_t, posix_spawnattr_t};
use crate::time::Duration;
use crate::sync::LazyLock;
// Get smallest amount of time we can sleep.
// Return a common value if it cannot be determined.
fn get_clock_resolution() -> Duration {
static MIN_DELAY: LazyLock<Duration, fn() -> Duration> = LazyLock::new(|| {
let mut mindelay = libc::timespec { tv_sec: 0, tv_nsec: 0 };
if unsafe { libc::clock_getres(libc::CLOCK_MONOTONIC, &mut mindelay) } == 0
{
Duration::from_nanos(mindelay.tv_nsec as u64)
} else {
Duration::from_millis(1)
}
});
*MIN_DELAY
}
// Arbitrary minimum sleep duration for retrying fork/spawn
const MIN_FORKSPAWN_SLEEP: Duration = Duration::from_nanos(1);
// Maximum duration of sleeping before giving up and returning an error
const MAX_FORKSPAWN_SLEEP: Duration = Duration::from_millis(1000);
}
}
////////////////////////////////////////////////////////////////////////////////
// Command
////////////////////////////////////////////////////////////////////////////////
impl Command {
pub fn spawn(
&mut self,
default: Stdio,
needs_stdin: bool,
) -> io::Result<(Process, StdioPipes)> {
const CLOEXEC_MSG_FOOTER: [u8; 4] = *b"NOEX";
let envp = self.capture_env();
if self.saw_nul() {
return Err(io::const_io_error!(
ErrorKind::InvalidInput,
"nul byte found in provided data",
));
}
let (ours, theirs) = self.setup_io(default, needs_stdin)?;
if let Some(ret) = self.posix_spawn(&theirs, envp.as_ref())? {
return Ok((ret, ours));
}
#[cfg(target_os = "linux")]
let (input, output) = sys::net::Socket::new_pair(libc::AF_UNIX, libc::SOCK_SEQPACKET)?;
#[cfg(not(target_os = "linux"))]
let (input, output) = sys::pipe::anon_pipe()?;
// Whatever happens after the fork is almost for sure going to touch or
// look at the environment in one way or another (PATH in `execvp` or
// accessing the `environ` pointer ourselves). Make sure no other thread
// is accessing the environment when we do the fork itself.
//
// Note that as soon as we're done with the fork there's no need to hold
// a lock any more because the parent won't do anything and the child is
// in its own process. Thus the parent drops the lock guard immediately.
// The child calls `mem::forget` to leak the lock, which is crucial because
// releasing a lock is not async-signal-safe.
let env_lock = sys::os::env_read_lock();
let pid = unsafe { self.do_fork()? };
if pid == 0 {
crate::panic::always_abort();
mem::forget(env_lock); // avoid non-async-signal-safe unlocking
drop(input);
#[cfg(target_os = "linux")]
if self.get_create_pidfd() {
self.send_pidfd(&output);
}
let Err(err) = unsafe { self.do_exec(theirs, envp.as_ref()) };
let errno = err.raw_os_error().unwrap_or(libc::EINVAL) as u32;
let errno = errno.to_be_bytes();
let bytes = [
errno[0],
errno[1],
errno[2],
errno[3],
CLOEXEC_MSG_FOOTER[0],
CLOEXEC_MSG_FOOTER[1],
CLOEXEC_MSG_FOOTER[2],
CLOEXEC_MSG_FOOTER[3],
];
// pipe I/O up to PIPE_BUF bytes should be atomic, and then
// we want to be sure we *don't* run at_exit destructors as
// we're being torn down regardless
rtassert!(output.write(&bytes).is_ok());
unsafe { libc::_exit(1) }
}
drop(env_lock);
drop(output);
#[cfg(target_os = "linux")]
let pidfd = if self.get_create_pidfd() { self.recv_pidfd(&input) } else { -1 };
#[cfg(not(target_os = "linux"))]
let pidfd = -1;
// Safety: We obtained the pidfd from calling `clone3` with
// `CLONE_PIDFD` so it's valid an otherwise unowned.
let mut p = unsafe { Process::new(pid, pidfd) };
let mut bytes = [0; 8];
// loop to handle EINTR
loop {
match input.read(&mut bytes) {
Ok(0) => return Ok((p, ours)),
Ok(8) => {
let (errno, footer) = bytes.split_at(4);
assert_eq!(
CLOEXEC_MSG_FOOTER, footer,
"Validation on the CLOEXEC pipe failed: {:?}",
bytes
);
let errno = i32::from_be_bytes(errno.try_into().unwrap());
assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
return Err(Error::from_raw_os_error(errno));
}
Err(ref e) if e.is_interrupted() => {}
Err(e) => {
assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
panic!("the CLOEXEC pipe failed: {e:?}")
}
Ok(..) => {
// pipe I/O up to PIPE_BUF bytes should be atomic
// similarly SOCK_SEQPACKET messages should arrive whole
assert!(p.wait().is_ok(), "wait() should either return Ok or panic");
panic!("short read on the CLOEXEC pipe")
}
}
}
}
pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> {
let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?;
crate::sys_common::process::wait_with_output(proc, pipes)
}
// WatchOS and TVOS headers mark the `fork`/`exec*` functions with
// `__WATCHOS_PROHIBITED __TVOS_PROHIBITED`, and indicate that the
// `posix_spawn*` functions should be used instead. It isn't entirely clear
// what `PROHIBITED` means here (e.g. if calls to these functions are
// allowed to exist in dead code), but it sounds bad, so we go out of our
// way to avoid that all-together.
#[cfg(any(target_os = "tvos", target_os = "watchos"))]
const ERR_APPLE_TV_WATCH_NO_FORK_EXEC: Error = io::const_io_error!(
ErrorKind::Unsupported,
"`fork`+`exec`-based process spawning is not supported on this target",
);
#[cfg(any(target_os = "tvos", target_os = "watchos"))]
unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
}
// Attempts to fork the process. If successful, returns Ok((0, -1))
// in the child, and Ok((child_pid, -1)) in the parent.
#[cfg(not(any(
target_os = "watchos",
target_os = "tvos",
all(target_os = "nto", target_env = "nto71"),
)))]
unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
cvt(libc::fork())
}
// On QNX Neutrino, fork can fail with EBADF in case "another thread might have opened
// or closed a file descriptor while the fork() was occurring".
// Documentation says "... or try calling fork() again". This is what we do here.
// See also https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/f/fork.html
#[cfg(all(target_os = "nto", target_env = "nto71"))]
unsafe fn do_fork(&mut self) -> Result<pid_t, io::Error> {
use crate::sys::os::errno;
let mut delay = MIN_FORKSPAWN_SLEEP;
loop {
let r = libc::fork();
if r == -1 as libc::pid_t && errno() as libc::c_int == libc::EBADF {
if delay < get_clock_resolution() {
// We cannot sleep this short (it would be longer).
// Yield instead.
thread::yield_now();
} else if delay < MAX_FORKSPAWN_SLEEP {
thread::sleep(delay);
} else {
return Err(io::const_io_error!(
ErrorKind::WouldBlock,
"forking returned EBADF too often",
));
}
delay *= 2;
continue;
} else {
return cvt(r);
}
}
}
pub fn exec(&mut self, default: Stdio) -> io::Error {
let envp = self.capture_env();
if self.saw_nul() {
return io::const_io_error!(ErrorKind::InvalidInput, "nul byte found in provided data",);
}
match self.setup_io(default, true) {
Ok((_, theirs)) => {
unsafe {
// Similar to when forking, we want to ensure that access to
// the environment is synchronized, so make sure to grab the
// environment lock before we try to exec.
let _lock = sys::os::env_read_lock();
let Err(e) = self.do_exec(theirs, envp.as_ref());
e
}
}
Err(e) => e,
}
}
// And at this point we've reached a special time in the life of the
// child. The child must now be considered hamstrung and unable to
// do anything other than syscalls really. Consider the following
// scenario:
//
// 1. Thread A of process 1 grabs the malloc() mutex
// 2. Thread B of process 1 forks(), creating thread C
// 3. Thread C of process 2 then attempts to malloc()
// 4. The memory of process 2 is the same as the memory of
// process 1, so the mutex is locked.
//
// This situation looks a lot like deadlock, right? It turns out
// that this is what pthread_atfork() takes care of, which is
// presumably implemented across platforms. The first thing that
// threads to *before* forking is to do things like grab the malloc
// mutex, and then after the fork they unlock it.
//
// Despite this information, libnative's spawn has been witnessed to
// deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
// all collected backtraces point at malloc/free traffic in the
// child spawned process.
//
// For this reason, the block of code below should contain 0
// invocations of either malloc of free (or their related friends).
//
// As an example of not having malloc/free traffic, we don't close
// this file descriptor by dropping the FileDesc (which contains an
// allocation). Instead we just close it manually. This will never
// have the drop glue anyway because this code never returns (the
// child will either exec() or invoke libc::exit)
#[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
unsafe fn do_exec(
&mut self,
stdio: ChildPipes,
maybe_envp: Option<&CStringArray>,
) -> Result<!, io::Error> {
use crate::sys::{self, cvt_r};
if let Some(fd) = stdio.stdin.fd() {
cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
}
if let Some(fd) = stdio.stdout.fd() {
cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
}
if let Some(fd) = stdio.stderr.fd() {
cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
}
#[cfg(not(target_os = "l4re"))]
{
if let Some(_g) = self.get_groups() {
//FIXME: Redox kernel does not support setgroups yet
#[cfg(not(target_os = "redox"))]
cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
}
if let Some(u) = self.get_gid() {
cvt(libc::setgid(u as gid_t))?;
}
if let Some(u) = self.get_uid() {
// When dropping privileges from root, the `setgroups` call
// will remove any extraneous groups. We only drop groups
// if the current uid is 0 and we weren't given an explicit
// set of groups. If we don't call this, then even though our
// uid has dropped, we may still have groups that enable us to
// do super-user things.
//FIXME: Redox kernel does not support setgroups yet
#[cfg(not(target_os = "redox"))]
if libc::getuid() == 0 && self.get_groups().is_none() {
cvt(libc::setgroups(0, crate::ptr::null()))?;
}
cvt(libc::setuid(u as uid_t))?;
}
}
if let Some(ref cwd) = *self.get_cwd() {
cvt(libc::chdir(cwd.as_ptr()))?;
}
if let Some(pgroup) = self.get_pgroup() {
cvt(libc::setpgid(0, pgroup))?;
}
// emscripten has no signal support.
#[cfg(not(target_os = "emscripten"))]
{
// Inherit the signal mask from the parent rather than resetting it (i.e. do not call
// pthread_sigmask).
// If #[unix_sigpipe] is specified, don't reset SIGPIPE to SIG_DFL.
// If #[unix_sigpipe] is not specified, reset SIGPIPE to SIG_DFL for backward compatibility.
//
// #[unix_sigpipe] is an opportunity to change the default here.
if !crate::sys::unix_sigpipe_attr_specified() {
#[cfg(target_os = "android")] // see issue #88585
{
let mut action: libc::sigaction = mem::zeroed();
action.sa_sigaction = libc::SIG_DFL;
cvt(libc::sigaction(libc::SIGPIPE, &action, crate::ptr::null_mut()))?;
}
#[cfg(not(target_os = "android"))]
{
let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL);
if ret == libc::SIG_ERR {
return Err(io::Error::last_os_error());
}
}
#[cfg(target_os = "hurd")]
{
let ret = sys::signal(libc::SIGLOST, libc::SIG_DFL);
if ret == libc::SIG_ERR {
return Err(io::Error::last_os_error());
}
}
}
}
for callback in self.get_closures().iter_mut() {
callback()?;
}
// Although we're performing an exec here we may also return with an
// error from this function (without actually exec'ing) in which case we
// want to be sure to restore the global environment back to what it
// once was, ensuring that our temporary override, when free'd, doesn't
// corrupt our process's environment.
let mut _reset = None;
if let Some(envp) = maybe_envp {
struct Reset(*const *const libc::c_char);
impl Drop for Reset {
fn drop(&mut self) {
unsafe {
*sys::os::environ() = self.0;
}
}
}
_reset = Some(Reset(*sys::os::environ()));
*sys::os::environ() = envp.as_ptr();
}
libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr());
Err(io::Error::last_os_error())
}
#[cfg(any(target_os = "tvos", target_os = "watchos"))]
unsafe fn do_exec(
&mut self,
_stdio: ChildPipes,
_maybe_envp: Option<&CStringArray>,
) -> Result<!, io::Error> {
return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
}
#[cfg(not(any(
target_os = "macos",
target_os = "tvos",
target_os = "watchos",
target_os = "freebsd",
all(target_os = "linux", target_env = "gnu"),
all(target_os = "linux", target_env = "musl"),
target_os = "nto",
)))]
fn posix_spawn(
&mut self,
_: &ChildPipes,
_: Option<&CStringArray>,
) -> io::Result<Option<Process>> {
Ok(None)
}
// Only support platforms for which posix_spawn() can return ENOENT
// directly.
#[cfg(any(
target_os = "macos",
// FIXME: `target_os = "ios"`?
target_os = "tvos",
target_os = "watchos",
target_os = "freebsd",
all(target_os = "linux", target_env = "gnu"),
all(target_os = "linux", target_env = "musl"),
target_os = "nto",
))]
fn posix_spawn(
&mut self,
stdio: &ChildPipes,
envp: Option<&CStringArray>,
) -> io::Result<Option<Process>> {
use crate::mem::MaybeUninit;
use crate::sys::{self, cvt_nz, unix_sigpipe_attr_specified};
if self.get_gid().is_some()
|| self.get_uid().is_some()
|| (self.env_saw_path() && !self.program_is_path())
|| !self.get_closures().is_empty()
|| self.get_groups().is_some()
|| self.get_create_pidfd()
{
return Ok(None);
}
// Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
#[cfg(all(target_os = "linux", target_env = "gnu"))]
{
if let Some(version) = sys::os::glibc_version() {
if version < (2, 24) {
return Ok(None);
}
} else {
return Ok(None);
}
}
// On QNX Neutrino, posix_spawnp can fail with EBADF in case "another thread might have opened
// or closed a file descriptor while the posix_spawn() was occurring".
// Documentation says "... or try calling posix_spawn() again". This is what we do here.
// See also http://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/p/posix_spawn.html
#[cfg(all(target_os = "nto", target_env = "nto71"))]
unsafe fn retrying_libc_posix_spawnp(
pid: *mut pid_t,
file: *const c_char,
file_actions: *const posix_spawn_file_actions_t,
attrp: *const posix_spawnattr_t,
argv: *const *mut c_char,
envp: *const *mut c_char,
) -> io::Result<i32> {
let mut delay = MIN_FORKSPAWN_SLEEP;
loop {
match libc::posix_spawnp(pid, file, file_actions, attrp, argv, envp) {
libc::EBADF => {
if delay < get_clock_resolution() {
// We cannot sleep this short (it would be longer).
// Yield instead.
thread::yield_now();
} else if delay < MAX_FORKSPAWN_SLEEP {
thread::sleep(delay);
} else {
return Err(io::const_io_error!(
ErrorKind::WouldBlock,
"posix_spawnp returned EBADF too often",
));
}
delay *= 2;
continue;
}
r => {
return Ok(r);
}
}
}
}
// Solaris, glibc 2.29+, and musl 1.24+ can set a new working directory,
// and maybe others will gain this non-POSIX function too. We'll check
// for this weak symbol as soon as it's needed, so we can return early
// otherwise to do a manual chdir before exec.
weak! {
fn posix_spawn_file_actions_addchdir_np(
*mut libc::posix_spawn_file_actions_t,
*const libc::c_char
) -> libc::c_int
}
let addchdir = match self.get_cwd() {
Some(cwd) => {
if cfg!(any(target_os = "macos", target_os = "tvos", target_os = "watchos")) {
// There is a bug in macOS where a relative executable
// path like "../myprogram" will cause `posix_spawn` to
// successfully launch the program, but erroneously return
// ENOENT when used with posix_spawn_file_actions_addchdir_np
// which was introduced in macOS 10.15.
if self.get_program_kind() == ProgramKind::Relative {
return Ok(None);
}
}
match posix_spawn_file_actions_addchdir_np.get() {
Some(f) => Some((f, cwd)),
None => return Ok(None),
}
}
None => None,
};
let pgroup = self.get_pgroup();
// Safety: -1 indicates we don't have a pidfd.
let mut p = unsafe { Process::new(0, -1) };
struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
impl Drop for PosixSpawnFileActions<'_> {
fn drop(&mut self) {
unsafe {
libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
}
}
}
struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
impl Drop for PosixSpawnattr<'_> {
fn drop(&mut self) {
unsafe {
libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
}
}
}
unsafe {
let mut attrs = MaybeUninit::uninit();
cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
let attrs = PosixSpawnattr(&mut attrs);
let mut flags = 0;
let mut file_actions = MaybeUninit::uninit();
cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
let file_actions = PosixSpawnFileActions(&mut file_actions);
if let Some(fd) = stdio.stdin.fd() {
cvt_nz(libc::posix_spawn_file_actions_adddup2(
file_actions.0.as_mut_ptr(),
fd,
libc::STDIN_FILENO,
))?;
}
if let Some(fd) = stdio.stdout.fd() {
cvt_nz(libc::posix_spawn_file_actions_adddup2(
file_actions.0.as_mut_ptr(),
fd,
libc::STDOUT_FILENO,
))?;
}
if let Some(fd) = stdio.stderr.fd() {
cvt_nz(libc::posix_spawn_file_actions_adddup2(
file_actions.0.as_mut_ptr(),
fd,
libc::STDERR_FILENO,
))?;
}
if let Some((f, cwd)) = addchdir {
cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
}
if let Some(pgroup) = pgroup {
flags |= libc::POSIX_SPAWN_SETPGROUP;
cvt_nz(libc::posix_spawnattr_setpgroup(attrs.0.as_mut_ptr(), pgroup))?;
}
// Inherit the signal mask from this process rather than resetting it (i.e. do not call
// posix_spawnattr_setsigmask).
// If #[unix_sigpipe] is specified, don't reset SIGPIPE to SIG_DFL.
// If #[unix_sigpipe] is not specified, reset SIGPIPE to SIG_DFL for backward compatibility.
//
// #[unix_sigpipe] is an opportunity to change the default here.
if !unix_sigpipe_attr_specified() {
let mut default_set = MaybeUninit::<libc::sigset_t>::uninit();
cvt(sigemptyset(default_set.as_mut_ptr()))?;
cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGPIPE))?;
#[cfg(target_os = "hurd")]
{
cvt(sigaddset(default_set.as_mut_ptr(), libc::SIGLOST))?;
}
cvt_nz(libc::posix_spawnattr_setsigdefault(
attrs.0.as_mut_ptr(),
default_set.as_ptr(),
))?;
flags |= libc::POSIX_SPAWN_SETSIGDEF;
}
cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
// Make sure we synchronize access to the global `environ` resource
let _env_lock = sys::os::env_read_lock();
let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::os::environ() as *const _);
#[cfg(not(target_os = "nto"))]
let spawn_fn = libc::posix_spawnp;
#[cfg(target_os = "nto")]
let spawn_fn = retrying_libc_posix_spawnp;
let spawn_res = spawn_fn(
&mut p.pid,
self.get_program_cstr().as_ptr(),
file_actions.0.as_ptr(),
attrs.0.as_ptr(),
self.get_argv().as_ptr() as *const _,
envp as *const _,
);
#[cfg(target_os = "nto")]
let spawn_res = spawn_res?;
cvt_nz(spawn_res)?;
Ok(Some(p))
}
}
#[cfg(target_os = "linux")]
fn send_pidfd(&self, sock: &crate::sys::net::Socket) {
use crate::io::IoSlice;
use crate::os::fd::RawFd;
use crate::sys::cvt_r;
use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
unsafe {
let child_pid = libc::getpid();
// pidfd_open sets CLOEXEC by default
let pidfd = libc::syscall(libc::SYS_pidfd_open, child_pid, 0);
let fds: [c_int; 1] = [pidfd as RawFd];
const SCM_MSG_LEN: usize = mem::size_of::<[c_int; 1]>();
#[repr(C)]
union Cmsg {
buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
_align: libc::cmsghdr,
}
let mut cmsg: Cmsg = mem::zeroed();
// 0-length message to send through the socket so we can pass along the fd
let mut iov = [IoSlice::new(b"")];
let mut msg: libc::msghdr = mem::zeroed();
msg.msg_iov = &mut iov as *mut _ as *mut _;
msg.msg_iovlen = 1;
// only attach cmsg if we successfully acquired the pidfd
if pidfd >= 0 {
msg.msg_controllen = mem::size_of_val(&cmsg.buf) as _;
msg.msg_control = &mut cmsg.buf as *mut _ as *mut _;
let hdr = CMSG_FIRSTHDR(&mut msg as *mut _ as *mut _);
(*hdr).cmsg_level = SOL_SOCKET;
(*hdr).cmsg_type = SCM_RIGHTS;
(*hdr).cmsg_len = CMSG_LEN(SCM_MSG_LEN as _) as _;
let data = CMSG_DATA(hdr);
crate::ptr::copy_nonoverlapping(
fds.as_ptr().cast::<u8>(),
data as *mut _,
SCM_MSG_LEN,
);
}
// we send the 0-length message even if we failed to acquire the pidfd
// so we get a consistent SEQPACKET order
match cvt_r(|| libc::sendmsg(sock.as_raw(), &msg, 0)) {
Ok(0) => {}
other => rtabort!("failed to communicate with parent process. {:?}", other),
}
}
}
#[cfg(target_os = "linux")]
fn recv_pidfd(&self, sock: &crate::sys::net::Socket) -> pid_t {
use crate::io::IoSliceMut;
use crate::sys::cvt_r;
use libc::{CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_SPACE, SCM_RIGHTS, SOL_SOCKET};
unsafe {
const SCM_MSG_LEN: usize = mem::size_of::<[c_int; 1]>();
#[repr(C)]
union Cmsg {
_buf: [u8; unsafe { CMSG_SPACE(SCM_MSG_LEN as u32) as usize }],
_align: libc::cmsghdr,
}
let mut cmsg: Cmsg = mem::zeroed();
// 0-length read to get the fd
let mut iov = [IoSliceMut::new(&mut [])];
let mut msg: libc::msghdr = mem::zeroed();
msg.msg_iov = &mut iov as *mut _ as *mut _;
msg.msg_iovlen = 1;
msg.msg_controllen = mem::size_of::<Cmsg>() as _;
msg.msg_control = &mut cmsg as *mut _ as *mut _;
match cvt_r(|| libc::recvmsg(sock.as_raw(), &mut msg, libc::MSG_CMSG_CLOEXEC)) {
Err(_) => return -1,
Ok(_) => {}
}
let hdr = CMSG_FIRSTHDR(&mut msg as *mut _ as *mut _);
if hdr.is_null()
|| (*hdr).cmsg_level != SOL_SOCKET
|| (*hdr).cmsg_type != SCM_RIGHTS
|| (*hdr).cmsg_len != CMSG_LEN(SCM_MSG_LEN as _) as _
{
return -1;
}
let data = CMSG_DATA(hdr);
let mut fds = [-1 as c_int];
crate::ptr::copy_nonoverlapping(
data as *const _,
fds.as_mut_ptr().cast::<u8>(),
SCM_MSG_LEN,
);
fds[0]
}
}
}
////////////////////////////////////////////////////////////////////////////////
// Processes
////////////////////////////////////////////////////////////////////////////////
/// The unique ID of the process (this should never be negative).
pub struct Process {
pid: pid_t,
status: Option<ExitStatus>,
// On Linux, stores the pidfd created for this child.
// This is None if the user did not request pidfd creation,
// or if the pidfd could not be created for some reason
// (e.g. the `pidfd_open` syscall was not available).
#[cfg(target_os = "linux")]
pidfd: Option<PidFd>,
}
impl Process {
#[cfg(target_os = "linux")]
unsafe fn new(pid: pid_t, pidfd: pid_t) -> Self {
use crate::os::unix::io::FromRawFd;
use crate::sys_common::FromInner;
// Safety: If `pidfd` is nonnegative, we assume it's valid and otherwise unowned.
let pidfd = (pidfd >= 0).then(|| PidFd::from_inner(sys::fd::FileDesc::from_raw_fd(pidfd)));
Process { pid, status: None, pidfd }
}
#[cfg(not(target_os = "linux"))]
unsafe fn new(pid: pid_t, _pidfd: pid_t) -> Self {
Process { pid, status: None }
}
pub fn id(&self) -> u32 {
self.pid as u32
}
pub fn kill(&mut self) -> io::Result<()> {
// If we've already waited on this process then the pid can be recycled
// and used for another process, and we probably shouldn't be killing
// random processes, so return Ok because the process has exited already.
if self.status.is_some() {
return Ok(());
}
#[cfg(target_os = "linux")]
if let Some(pid_fd) = self.pidfd.as_ref() {
// pidfd_send_signal predates pidfd_open. so if we were able to get an fd then sending signals will work too
return cvt(unsafe {
libc::syscall(
libc::SYS_pidfd_send_signal,
pid_fd.as_raw_fd(),
libc::SIGKILL,
crate::ptr::null::<()>(),
0,
)
})
.map(drop);
}
cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
}
pub fn wait(&mut self) -> io::Result<ExitStatus> {
use crate::sys::cvt_r;
if let Some(status) = self.status {
return Ok(status);
}
#[cfg(target_os = "linux")]
if let Some(pid_fd) = self.pidfd.as_ref() {
let mut siginfo: libc::siginfo_t = unsafe { crate::mem::zeroed() };
cvt_r(|| unsafe {
libc::waitid(libc::P_PIDFD, pid_fd.as_raw_fd() as u32, &mut siginfo, libc::WEXITED)
})?;
let status = ExitStatus::from_waitid_siginfo(siginfo);
self.status = Some(status);
return Ok(status);
}
let mut status = 0 as c_int;
cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
self.status = Some(ExitStatus::new(status));
Ok(ExitStatus::new(status))
}
pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
if let Some(status) = self.status {
return Ok(Some(status));
}
#[cfg(target_os = "linux")]
if let Some(pid_fd) = self.pidfd.as_ref() {
let mut siginfo: libc::siginfo_t = unsafe { crate::mem::zeroed() };
cvt(unsafe {
libc::waitid(
libc::P_PIDFD,
pid_fd.as_raw_fd() as u32,
&mut siginfo,
libc::WEXITED | libc::WNOHANG,
)
})?;
if unsafe { siginfo.si_pid() } == 0 {
return Ok(None);
}
let status = ExitStatus::from_waitid_siginfo(siginfo);
self.status = Some(status);
return Ok(Some(status));
}
let mut status = 0 as c_int;
let pid = cvt(unsafe { libc::waitpid(self.pid, &mut status, libc::WNOHANG) })?;
if pid == 0 {
Ok(None)
} else {
self.status = Some(ExitStatus::new(status));
Ok(Some(ExitStatus::new(status)))
}
}
}
/// Unix exit statuses
//
// This is not actually an "exit status" in Unix terminology. Rather, it is a "wait status".
// See the discussion in comments and doc comments for `std::process::ExitStatus`.
#[derive(PartialEq, Eq, Clone, Copy, Default)]
pub struct ExitStatus(c_int);
impl fmt::Debug for ExitStatus {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("unix_wait_status").field(&self.0).finish()
}
}
impl ExitStatus {
pub fn new(status: c_int) -> ExitStatus {
ExitStatus(status)
}
#[cfg(target_os = "linux")]
pub fn from_waitid_siginfo(siginfo: libc::siginfo_t) -> ExitStatus {
let status = unsafe { siginfo.si_status() };
match siginfo.si_code {
libc::CLD_EXITED => ExitStatus((status & 0xff) << 8),
libc::CLD_KILLED => ExitStatus(status),
libc::CLD_DUMPED => ExitStatus(status | 0x80),
libc::CLD_CONTINUED => ExitStatus(0xffff),
libc::CLD_STOPPED | libc::CLD_TRAPPED => ExitStatus(((status & 0xff) << 8) | 0x7f),
_ => unreachable!("waitid() should only return the above codes"),
}
}
fn exited(&self) -> bool {
libc::WIFEXITED(self.0)
}
pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
// This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is
// true on all actual versions of Unix, is widely assumed, and is specified in SuS
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html. If it is not
// true for a platform pretending to be Unix, the tests (our doctests, and also
// process_unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too.
match NonZero_c_int::try_from(self.0) {
/* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)),
/* was zero, couldn't convert */ Err(_) => Ok(()),
}
}
pub fn code(&self) -> Option<i32> {
self.exited().then(|| libc::WEXITSTATUS(self.0))
}
pub fn signal(&self) -> Option<i32> {
libc::WIFSIGNALED(self.0).then(|| libc::WTERMSIG(self.0))
}
pub fn core_dumped(&self) -> bool {
libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
}
pub fn stopped_signal(&self) -> Option<i32> {
libc::WIFSTOPPED(self.0).then(|| libc::WSTOPSIG(self.0))
}
pub fn continued(&self) -> bool {
libc::WIFCONTINUED(self.0)
}
pub fn into_raw(&self) -> c_int {
self.0
}
}
/// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
impl From<c_int> for ExitStatus {
fn from(a: c_int) -> ExitStatus {
ExitStatus(a)
}
}
/// Convert a signal number to a readable, searchable name.
///
/// This string should be displayed right after the signal number.
/// If a signal is unrecognized, it returns the empty string, so that
/// you just get the number like "0". If it is recognized, you'll get
/// something like "9 (SIGKILL)".
fn signal_string(signal: i32) -> &'static str {
match signal {
libc::SIGHUP => " (SIGHUP)",
libc::SIGINT => " (SIGINT)",
libc::SIGQUIT => " (SIGQUIT)",
libc::SIGILL => " (SIGILL)",
libc::SIGTRAP => " (SIGTRAP)",
libc::SIGABRT => " (SIGABRT)",
#[cfg(not(target_os = "l4re"))]
libc::SIGBUS => " (SIGBUS)",
libc::SIGFPE => " (SIGFPE)",
libc::SIGKILL => " (SIGKILL)",
#[cfg(not(target_os = "l4re"))]
libc::SIGUSR1 => " (SIGUSR1)",
libc::SIGSEGV => " (SIGSEGV)",
#[cfg(not(target_os = "l4re"))]
libc::SIGUSR2 => " (SIGUSR2)",
libc::SIGPIPE => " (SIGPIPE)",
libc::SIGALRM => " (SIGALRM)",
libc::SIGTERM => " (SIGTERM)",
#[cfg(not(target_os = "l4re"))]
libc::SIGCHLD => " (SIGCHLD)",
#[cfg(not(target_os = "l4re"))]
libc::SIGCONT => " (SIGCONT)",
#[cfg(not(target_os = "l4re"))]
libc::SIGSTOP => " (SIGSTOP)",
#[cfg(not(target_os = "l4re"))]
libc::SIGTSTP => " (SIGTSTP)",
#[cfg(not(target_os = "l4re"))]
libc::SIGTTIN => " (SIGTTIN)",
#[cfg(not(target_os = "l4re"))]
libc::SIGTTOU => " (SIGTTOU)",
#[cfg(not(target_os = "l4re"))]
libc::SIGURG => " (SIGURG)",
#[cfg(not(target_os = "l4re"))]
libc::SIGXCPU => " (SIGXCPU)",
#[cfg(not(target_os = "l4re"))]
libc::SIGXFSZ => " (SIGXFSZ)",
#[cfg(not(target_os = "l4re"))]
libc::SIGVTALRM => " (SIGVTALRM)",
#[cfg(not(target_os = "l4re"))]
libc::SIGPROF => " (SIGPROF)",
#[cfg(not(target_os = "l4re"))]
libc::SIGWINCH => " (SIGWINCH)",
#[cfg(not(any(target_os = "haiku", target_os = "l4re")))]
libc::SIGIO => " (SIGIO)",
#[cfg(target_os = "haiku")]
libc::SIGPOLL => " (SIGPOLL)",
#[cfg(not(target_os = "l4re"))]
libc::SIGSYS => " (SIGSYS)",
// For information on Linux signals, run `man 7 signal`
#[cfg(all(
target_os = "linux",
any(
target_arch = "x86_64",
target_arch = "x86",
target_arch = "arm",
target_arch = "aarch64"
)
))]
libc::SIGSTKFLT => " (SIGSTKFLT)",
#[cfg(any(target_os = "linux", target_os = "nto"))]
libc::SIGPWR => " (SIGPWR)",
#[cfg(any(
target_os = "macos",
target_os = "ios",
target_os = "tvos",
target_os = "freebsd",
target_os = "netbsd",
target_os = "openbsd",
target_os = "dragonfly",
target_os = "nto",
))]
libc::SIGEMT => " (SIGEMT)",
#[cfg(any(
target_os = "macos",
target_os = "ios",
target_os = "tvos",
target_os = "freebsd",
target_os = "netbsd",
target_os = "openbsd",
target_os = "dragonfly"
))]
libc::SIGINFO => " (SIGINFO)",
#[cfg(target_os = "hurd")]
libc::SIGLOST => " (SIGLOST)",
_ => "",
}
}
impl fmt::Display for ExitStatus {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(code) = self.code() {
write!(f, "exit status: {code}")
} else if let Some(signal) = self.signal() {
let signal_string = signal_string(signal);
if self.core_dumped() {
write!(f, "signal: {signal}{signal_string} (core dumped)")
} else {
write!(f, "signal: {signal}{signal_string}")
}
} else if let Some(signal) = self.stopped_signal() {
let signal_string = signal_string(signal);
write!(f, "stopped (not terminated) by signal: {signal}{signal_string}")
} else if self.continued() {
write!(f, "continued (WIFCONTINUED)")
} else {
write!(f, "unrecognised wait status: {} {:#x}", self.0, self.0)
}
}
}
#[derive(PartialEq, Eq, Clone, Copy)]
pub struct ExitStatusError(NonZero_c_int);
impl Into<ExitStatus> for ExitStatusError {
fn into(self) -> ExitStatus {
ExitStatus(self.0.into())
}
}
impl fmt::Debug for ExitStatusError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("unix_wait_status").field(&self.0).finish()
}
}
impl ExitStatusError {
pub fn code(self) -> Option<NonZeroI32> {
ExitStatus(self.0.into()).code().map(|st| st.try_into().unwrap())
}
}
#[cfg(target_os = "linux")]
#[unstable(feature = "linux_pidfd", issue = "82971")]
impl crate::os::linux::process::ChildExt for crate::process::Child {
fn pidfd(&self) -> io::Result<&PidFd> {
self.handle
.pidfd
.as_ref()
.ok_or_else(|| Error::new(ErrorKind::Uncategorized, "No pidfd was created."))
}
fn take_pidfd(&mut self) -> io::Result<PidFd> {
self.handle
.pidfd
.take()
.ok_or_else(|| Error::new(ErrorKind::Uncategorized, "No pidfd was created."))
}
}
#[cfg(test)]
#[path = "process_unix/tests.rs"]
mod tests;
// See [`process_unsupported_wait_status::compare_with_linux`];
#[cfg(all(test, target_os = "linux"))]
#[path = "process_unsupported/wait_status.rs"]
mod process_unsupported_wait_status;