diff options
Diffstat (limited to 'src/libstd/sys/unix/process/process_unix.rs')
| -rw-r--r-- | src/libstd/sys/unix/process/process_unix.rs | 494 |
1 files changed, 0 insertions, 494 deletions
diff --git a/src/libstd/sys/unix/process/process_unix.rs b/src/libstd/sys/unix/process/process_unix.rs deleted file mode 100644 index 0f349dfa302..00000000000 --- a/src/libstd/sys/unix/process/process_unix.rs +++ /dev/null @@ -1,494 +0,0 @@ -use crate::convert::TryInto; -use crate::fmt; -use crate::io::{self, Error, ErrorKind}; -use crate::ptr; -use crate::sys; -use crate::sys::cvt; -use crate::sys::process::process_common::*; - -use libc::{c_int, gid_t, pid_t, uid_t}; - -//////////////////////////////////////////////////////////////////////////////// -// 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::Error::new(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)); - } - - 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. - let result = unsafe { - let _env_lock = sys::os::env_lock(); - cvt(libc::fork())? - }; - - let pid = unsafe { - match result { - 0 => { - drop(input); - let Err(err) = 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 - assert!(output.write(&bytes).is_ok()); - libc::_exit(1) - } - n => n, - } - }; - - let mut p = Process { pid, status: None }; - drop(output); - 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.kind() == ErrorKind::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 - assert!(p.wait().is_ok(), "wait() should either return Ok or panic"); - panic!("short read on the CLOEXEC pipe") - } - } - } - } - - pub fn exec(&mut self, default: Stdio) -> io::Error { - let envp = self.capture_env(); - - if self.saw_nul() { - return io::Error::new(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_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) - 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(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. 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. This will - // fail if we aren't root, so don't bother checking the - // return value, this is just done as an optimistic - // privilege dropping function. - //FIXME: Redox kernel does not support setgroups yet - #[cfg(not(target_os = "redox"))] - let _ = libc::setgroups(0, ptr::null()); - cvt(libc::setuid(u as uid_t))?; - } - } - if let Some(ref cwd) = *self.get_cwd() { - cvt(libc::chdir(cwd.as_ptr()))?; - } - - // emscripten has no signal support. - #[cfg(not(target_os = "emscripten"))] - { - use crate::mem::MaybeUninit; - // Reset signal handling so the child process starts in a - // standardized state. libstd ignores SIGPIPE, and signal-handling - // libraries often set a mask. Child processes inherit ignored - // signals and the signal mask from their parent, but most - // UNIX programs do not reset these things on their own, so we - // need to clean things up now to avoid confusing the program - // we're about to run. - let mut set = MaybeUninit::<libc::sigset_t>::uninit(); - cvt(sigemptyset(set.as_mut_ptr()))?; - cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), ptr::null_mut()))?; - let ret = sys::signal(libc::SIGPIPE, 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().as_ptr(), self.get_argv().as_ptr()); - Err(io::Error::last_os_error()) - } - - #[cfg(not(any( - target_os = "macos", - target_os = "freebsd", - all(target_os = "linux", target_env = "gnu") - )))] - 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", - target_os = "freebsd", - all(target_os = "linux", target_env = "gnu") - ))] - fn posix_spawn( - &mut self, - stdio: &ChildPipes, - envp: Option<&CStringArray>, - ) -> io::Result<Option<Process>> { - use crate::mem::MaybeUninit; - use crate::sys; - - if self.get_gid().is_some() - || self.get_uid().is_some() - || self.env_saw_path() - || !self.get_closures().is_empty() - { - 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); - } - } - - // Solaris and glibc 2.29+ 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) => match posix_spawn_file_actions_addchdir_np.get() { - Some(f) => Some((f, cwd)), - None => return Ok(None), - }, - None => None, - }; - - let mut p = Process { pid: 0, status: None }; - - struct PosixSpawnFileActions(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(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 file_actions = PosixSpawnFileActions(MaybeUninit::uninit()); - let mut attrs = PosixSpawnattr(MaybeUninit::uninit()); - - libc::posix_spawnattr_init(attrs.0.as_mut_ptr()); - libc::posix_spawn_file_actions_init(file_actions.0.as_mut_ptr()); - - if let Some(fd) = stdio.stdin.fd() { - cvt(libc::posix_spawn_file_actions_adddup2( - file_actions.0.as_mut_ptr(), - fd, - libc::STDIN_FILENO, - ))?; - } - if let Some(fd) = stdio.stdout.fd() { - cvt(libc::posix_spawn_file_actions_adddup2( - file_actions.0.as_mut_ptr(), - fd, - libc::STDOUT_FILENO, - ))?; - } - if let Some(fd) = stdio.stderr.fd() { - cvt(libc::posix_spawn_file_actions_adddup2( - file_actions.0.as_mut_ptr(), - fd, - libc::STDERR_FILENO, - ))?; - } - if let Some((f, cwd)) = addchdir { - cvt(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?; - } - - let mut set = MaybeUninit::<libc::sigset_t>::uninit(); - cvt(sigemptyset(set.as_mut_ptr()))?; - cvt(libc::posix_spawnattr_setsigmask(attrs.0.as_mut_ptr(), set.as_ptr()))?; - cvt(sigaddset(set.as_mut_ptr(), libc::SIGPIPE))?; - cvt(libc::posix_spawnattr_setsigdefault(attrs.0.as_mut_ptr(), set.as_ptr()))?; - - let flags = libc::POSIX_SPAWN_SETSIGDEF | libc::POSIX_SPAWN_SETSIGMASK; - cvt(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_lock(); - let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::os::environ() as *const _); - let ret = libc::posix_spawnp( - &mut p.pid, - self.get_program().as_ptr(), - file_actions.0.as_ptr(), - attrs.0.as_ptr(), - self.get_argv().as_ptr() as *const _, - envp as *const _, - ); - if ret == 0 { Ok(Some(p)) } else { Err(io::Error::from_raw_os_error(ret)) } - } - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Processes -//////////////////////////////////////////////////////////////////////////////// - -/// The unique ID of the process (this should never be negative). -pub struct Process { - pid: pid_t, - status: Option<ExitStatus>, -} - -impl Process { - 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 just return an error. - if self.status.is_some() { - Err(Error::new( - ErrorKind::InvalidInput, - "invalid argument: can't kill an exited process", - )) - } else { - 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); - } - 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)); - } - 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 -#[derive(PartialEq, Eq, Clone, Copy, Debug)] -pub struct ExitStatus(c_int); - -impl ExitStatus { - pub fn new(status: c_int) -> ExitStatus { - ExitStatus(status) - } - - fn exited(&self) -> bool { - unsafe { libc::WIFEXITED(self.0) } - } - - pub fn success(&self) -> bool { - self.code() == Some(0) - } - - pub fn code(&self) -> Option<i32> { - if self.exited() { Some(unsafe { libc::WEXITSTATUS(self.0) }) } else { None } - } - - pub fn signal(&self) -> Option<i32> { - if !self.exited() { Some(unsafe { libc::WTERMSIG(self.0) }) } else { None } - } -} - -/// 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) - } -} - -impl fmt::Display for ExitStatus { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - if let Some(code) = self.code() { - write!(f, "exit code: {}", code) - } else { - let signal = self.signal().unwrap(); - write!(f, "signal: {}", signal) - } - } -} |