diff options
Diffstat (limited to 'ctr-std/src/sys/unix/process/process_unix.rs')
| -rw-r--r-- | ctr-std/src/sys/unix/process/process_unix.rs | 405 |
1 files changed, 405 insertions, 0 deletions
diff --git a/ctr-std/src/sys/unix/process/process_unix.rs b/ctr-std/src/sys/unix/process/process_unix.rs new file mode 100644 index 0000000..9d6d607 --- /dev/null +++ b/ctr-std/src/sys/unix/process/process_unix.rs @@ -0,0 +1,405 @@ +// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use io::{self, Error, ErrorKind}; +use libc::{self, c_int, gid_t, pid_t, uid_t}; +use ptr; + +use sys::cvt; +use sys::process::process_common::*; + +//////////////////////////////////////////////////////////////////////////////// +// Command +//////////////////////////////////////////////////////////////////////////////// + +impl Command { + pub fn spawn(&mut self, default: Stdio, needs_stdin: bool) + -> io::Result<(Process, StdioPipes)> { + use sys; + + const CLOEXEC_MSG_FOOTER: &'static [u8] = 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()?; + + let pid = unsafe { + match cvt(libc::fork())? { + 0 => { + drop(input); + let err = self.do_exec(theirs, envp.as_ref()); + let errno = err.raw_os_error().unwrap_or(libc::EINVAL) as u32; + let bytes = [ + (errno >> 24) as u8, + (errno >> 16) as u8, + (errno >> 8) as u8, + (errno >> 0) as u8, + 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: 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) => { + assert!(combine(CLOEXEC_MSG_FOOTER) == combine(&bytes[4.. 8]), + "Validation on the CLOEXEC pipe failed: {:?}", bytes); + let errno = combine(&bytes[0.. 4]); + 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") + } + } + } + + fn combine(arr: &[u8]) -> i32 { + let a = arr[0] as u32; + let b = arr[1] as u32; + let c = arr[2] as u32; + let d = arr[3] as u32; + + ((a << 24) | (b << 16) | (c << 8) | (d << 0)) as i32 + } + } + + 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 { self.do_exec(theirs, envp.as_ref()) }, + 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> + ) -> io::Error { + use sys::{self, cvt_r}; + + macro_rules! t { + ($e:expr) => (match $e { + Ok(e) => e, + Err(e) => return e, + }) + } + + if let Some(fd) = stdio.stdin.fd() { + t!(cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))); + } + if let Some(fd) = stdio.stdout.fd() { + t!(cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))); + } + if let Some(fd) = stdio.stderr.fd() { + t!(cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))); + } + + if cfg!(not(any(target_os = "l4re"))) { + if let Some(u) = self.get_gid() { + t!(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. + let _ = libc::setgroups(0, ptr::null()); + + t!(cvt(libc::setuid(u as uid_t))); + } + } + if let Some(ref cwd) = *self.get_cwd() { + t!(cvt(libc::chdir(cwd.as_ptr()))); + } + if let Some(envp) = maybe_envp { + *sys::os::environ() = envp.as_ptr(); + } + + // emscripten has no signal support. + #[cfg(not(any(target_os = "emscripten")))] + { + use mem; + // 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: libc::sigset_t = mem::uninitialized(); + if cfg!(target_os = "android") { + // Implementing sigemptyset allow us to support older Android + // versions. See the comment about Android and sig* functions in + // process_common.rs + libc::memset(&mut set as *mut _ as *mut _, + 0, + mem::size_of::<libc::sigset_t>()); + } else { + t!(cvt(libc::sigemptyset(&mut set))); + } + t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set, + ptr::null_mut()))); + let ret = sys::signal(libc::SIGPIPE, libc::SIG_DFL); + if ret == libc::SIG_ERR { + return io::Error::last_os_error() + } + } + + for callback in self.get_closures().iter_mut() { + t!(callback()); + } + + libc::execvp(self.get_argv()[0], self.get_argv().as_ptr()); + 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 mem; + use sys; + + if self.get_cwd().is_some() || + self.get_gid().is_some() || + self.get_uid().is_some() || + self.env_saw_path() || + self.get_closures().len() != 0 { + 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) + } + } + + let mut p = Process { pid: 0, status: None }; + + struct PosixSpawnFileActions(libc::posix_spawn_file_actions_t); + + impl Drop for PosixSpawnFileActions { + fn drop(&mut self) { + unsafe { + libc::posix_spawn_file_actions_destroy(&mut self.0); + } + } + } + + struct PosixSpawnattr(libc::posix_spawnattr_t); + + impl Drop for PosixSpawnattr { + fn drop(&mut self) { + unsafe { + libc::posix_spawnattr_destroy(&mut self.0); + } + } + } + + unsafe { + let mut file_actions = PosixSpawnFileActions(mem::uninitialized()); + let mut attrs = PosixSpawnattr(mem::uninitialized()); + + libc::posix_spawnattr_init(&mut attrs.0); + libc::posix_spawn_file_actions_init(&mut file_actions.0); + + if let Some(fd) = stdio.stdin.fd() { + cvt(libc::posix_spawn_file_actions_adddup2(&mut file_actions.0, + fd, + libc::STDIN_FILENO))?; + } + if let Some(fd) = stdio.stdout.fd() { + cvt(libc::posix_spawn_file_actions_adddup2(&mut file_actions.0, + fd, + libc::STDOUT_FILENO))?; + } + if let Some(fd) = stdio.stderr.fd() { + cvt(libc::posix_spawn_file_actions_adddup2(&mut file_actions.0, + fd, + libc::STDERR_FILENO))?; + } + + let mut set: libc::sigset_t = mem::uninitialized(); + cvt(libc::sigemptyset(&mut set))?; + cvt(libc::posix_spawnattr_setsigmask(&mut attrs.0, + &set))?; + cvt(libc::sigaddset(&mut set, libc::SIGPIPE))?; + cvt(libc::posix_spawnattr_setsigdefault(&mut attrs.0, + &set))?; + + let flags = libc::POSIX_SPAWN_SETSIGDEF | + libc::POSIX_SPAWN_SETSIGMASK; + cvt(libc::posix_spawnattr_setflags(&mut attrs.0, flags as _))?; + + let envp = envp.map(|c| c.as_ptr()) + .unwrap_or(*sys::os::environ() as *const _); + let ret = libc::posix_spawnp( + &mut p.pid, + self.get_argv()[0], + &file_actions.0, + &attrs.0, + 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(|_| ()) + } + } + + pub fn wait(&mut self) -> io::Result<ExitStatus> { + use 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))) + } + } +} |