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Diffstat (limited to 'src/libstd/sys/unix/process.rs')
| -rw-r--r-- | src/libstd/sys/unix/process.rs | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs new file mode 100644 index 00000000000..290310f4ad9 --- /dev/null +++ b/src/libstd/sys/unix/process.rs @@ -0,0 +1,414 @@ +// 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 prelude::v1::*; +use os::unix::prelude::*; + +use collections::HashMap; +use env; +use ffi::{OsString, OsStr, CString, CStr}; +use fmt; +use io::{self, Error, ErrorKind}; +use libc::{self, pid_t, c_void, c_int, gid_t, uid_t}; +use ptr; +use sys::pipe::AnonPipe; +use sys::{self, c, cvt, cvt_r}; +use sys::fs::{File, OpenOptions}; + +//////////////////////////////////////////////////////////////////////////////// +// Command +//////////////////////////////////////////////////////////////////////////////// + +#[derive(Clone)] +pub struct Command { + pub program: CString, + pub args: Vec<CString>, + pub env: Option<HashMap<OsString, OsString>>, + pub cwd: Option<CString>, + pub uid: Option<uid_t>, + pub gid: Option<gid_t>, + pub detach: bool, // not currently exposed in std::process +} + +impl Command { + pub fn new(program: &OsStr) -> Command { + Command { + program: program.to_cstring().unwrap(), + args: Vec::new(), + env: None, + cwd: None, + uid: None, + gid: None, + detach: false, + } + } + + pub fn arg(&mut self, arg: &OsStr) { + self.args.push(arg.to_cstring().unwrap()) + } + pub fn args<'a, I: Iterator<Item = &'a OsStr>>(&mut self, args: I) { + self.args.extend(args.map(|s| s.to_cstring().unwrap())) + } + fn init_env_map(&mut self) { + if self.env.is_none() { + self.env = Some(env::vars_os().collect()); + } + } + pub fn env(&mut self, key: &OsStr, val: &OsStr) { + self.init_env_map(); + self.env.as_mut().unwrap().insert(key.to_os_string(), val.to_os_string()); + } + pub fn env_remove(&mut self, key: &OsStr) { + self.init_env_map(); + self.env.as_mut().unwrap().remove(&key.to_os_string()); + } + pub fn env_clear(&mut self) { + self.env = Some(HashMap::new()) + } + pub fn cwd(&mut self, dir: &OsStr) { + self.cwd = Some(dir.to_cstring().unwrap()) + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Processes +//////////////////////////////////////////////////////////////////////////////// + +/// Unix exit statuses +#[derive(PartialEq, Eq, Clone, Copy, Debug)] +pub enum ExitStatus { + /// Normal termination with an exit code. + Code(i32), + + /// Termination by signal, with the signal number. + /// + /// Never generated on Windows. + Signal(i32), +} + +impl ExitStatus { + pub fn success(&self) -> bool { + *self == ExitStatus::Code(0) + } + pub fn code(&self) -> Option<i32> { + match *self { + ExitStatus::Code(c) => Some(c), + _ => None + } + } +} + +impl fmt::Display for ExitStatus { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + ExitStatus::Code(code) => write!(f, "exit code: {}", code), + ExitStatus::Signal(code) => write!(f, "signal: {}", code), + } + } +} + +/// The unique id of the process (this should never be negative). +pub struct Process { + pid: pid_t +} + +pub enum Stdio { + Inherit, + Piped(AnonPipe), + None, +} + +const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX"; + +impl Process { + pub unsafe fn kill(&self) -> io::Result<()> { + try!(cvt(libc::funcs::posix88::signal::kill(self.pid, libc::SIGKILL))); + Ok(()) + } + + pub fn spawn(cfg: &Command, + in_fd: Stdio, + out_fd: Stdio, + err_fd: Stdio) -> io::Result<Process> { + let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null()); + + let (envp, _a, _b) = make_envp(cfg.env.as_ref()); + let (argv, _a) = make_argv(&cfg.program, &cfg.args); + let (input, output) = try!(sys::pipe::anon_pipe()); + + let pid = unsafe { + match libc::fork() { + 0 => { + drop(input); + Process::child_after_fork(cfg, output, argv, envp, dirp, + in_fd, out_fd, err_fd) + } + n if n < 0 => return Err(Error::last_os_error()), + n => n, + } + }; + + let p = Process{ pid: pid }; + drop(output); + let mut bytes = [0; 8]; + + // loop to handle EINTR + loop { + match input.read(&mut bytes) { + Ok(0) => return Ok(p), + 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 + } + } + + // 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 OSX 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 child_after_fork(cfg: &Command, + mut output: AnonPipe, + argv: *const *const libc::c_char, + envp: *const libc::c_void, + dirp: *const libc::c_char, + in_fd: Stdio, + out_fd: Stdio, + err_fd: Stdio) -> ! { + fn fail(output: &mut AnonPipe) -> ! { + let errno = sys::os::errno() 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()); + unsafe { libc::_exit(1) } + } + + let setup = |src: Stdio, dst: c_int| { + let fd = match src { + Stdio::Inherit => return true, + Stdio::Piped(pipe) => pipe.into_fd(), + + // If a stdio file descriptor is set to be ignored, we open up + // /dev/null into that file descriptor. Otherwise, the first + // file descriptor opened up in the child would be numbered as + // one of the stdio file descriptors, which is likely to wreak + // havoc. + Stdio::None => { + let mut opts = OpenOptions::new(); + opts.read(dst == libc::STDIN_FILENO); + opts.write(dst != libc::STDIN_FILENO); + let devnull = CStr::from_ptr(b"/dev/null\0".as_ptr() + as *const _); + if let Ok(f) = File::open_c(devnull, &opts) { + f.into_fd() + } else { + return false + } + } + }; + cvt_r(|| libc::dup2(fd.raw(), dst)).is_ok() + }; + + if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) } + if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) } + if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) } + + if let Some(u) = cfg.gid { + if libc::setgid(u as libc::gid_t) != 0 { + fail(&mut output); + } + } + if let Some(u) = cfg.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 _ = c::setgroups(0, ptr::null()); + + if libc::setuid(u as libc::uid_t) != 0 { + fail(&mut output); + } + } + if cfg.detach { + // Don't check the error of setsid because it fails if we're the + // process leader already. We just forked so it shouldn't return + // error, but ignore it anyway. + let _ = libc::setsid(); + } + if !dirp.is_null() && libc::chdir(dirp) == -1 { + fail(&mut output); + } + if !envp.is_null() { + *sys::os::environ() = envp as *const _; + } + let _ = libc::execvp(*argv, argv as *mut _); + fail(&mut output) + } + + pub fn wait(&self) -> io::Result<ExitStatus> { + let mut status = 0 as c_int; + try!(cvt_r(|| unsafe { c::waitpid(self.pid, &mut status, 0) })); + Ok(translate_status(status)) + } + + pub fn try_wait(&self) -> Option<ExitStatus> { + let mut status = 0 as c_int; + match cvt_r(|| unsafe { + c::waitpid(self.pid, &mut status, c::WNOHANG) + }) { + Ok(0) => None, + Ok(n) if n == self.pid => Some(translate_status(status)), + Ok(n) => panic!("unknown pid: {}", n), + Err(e) => panic!("unknown waitpid error: {}", e), + } + } +} + +fn make_argv(prog: &CString, args: &[CString]) + -> (*const *const libc::c_char, Vec<*const libc::c_char>) +{ + let mut ptrs: Vec<*const libc::c_char> = Vec::with_capacity(args.len()+1); + + // Convert the CStrings into an array of pointers. Note: the + // lifetime of the various CStrings involved is guaranteed to be + // larger than the lifetime of our invocation of cb, but this is + // technically unsafe as the callback could leak these pointers + // out of our scope. + ptrs.push(prog.as_ptr()); + ptrs.extend(args.iter().map(|tmp| tmp.as_ptr())); + + // Add a terminating null pointer (required by libc). + ptrs.push(ptr::null()); + + (ptrs.as_ptr(), ptrs) +} + +fn make_envp(env: Option<&HashMap<OsString, OsString>>) + -> (*const c_void, Vec<Vec<u8>>, Vec<*const libc::c_char>) +{ + // On posixy systems we can pass a char** for envp, which is a + // null-terminated array of "k=v\0" strings. Since we must create + // these strings locally, yet expose a raw pointer to them, we + // create a temporary vector to own the CStrings that outlives the + // call to cb. + if let Some(env) = env { + let mut tmps = Vec::with_capacity(env.len()); + + for pair in env { + let mut kv = Vec::new(); + kv.push_all(pair.0.as_bytes()); + kv.push('=' as u8); + kv.push_all(pair.1.as_bytes()); + kv.push(0); // terminating null + tmps.push(kv); + } + + let mut ptrs: Vec<*const libc::c_char> = + tmps.iter() + .map(|tmp| tmp.as_ptr() as *const libc::c_char) + .collect(); + ptrs.push(ptr::null()); + + (ptrs.as_ptr() as *const _, tmps, ptrs) + } else { + (0 as *const _, Vec::new(), Vec::new()) + } +} + +fn translate_status(status: c_int) -> ExitStatus { + #![allow(non_snake_case)] + #[cfg(any(target_os = "linux", target_os = "android"))] + mod imp { + pub fn WIFEXITED(status: i32) -> bool { (status & 0xff) == 0 } + pub fn WEXITSTATUS(status: i32) -> i32 { (status >> 8) & 0xff } + pub fn WTERMSIG(status: i32) -> i32 { status & 0x7f } + } + + #[cfg(any(target_os = "macos", + target_os = "ios", + target_os = "freebsd", + target_os = "dragonfly", + target_os = "bitrig", + target_os = "openbsd"))] + mod imp { + pub fn WIFEXITED(status: i32) -> bool { (status & 0x7f) == 0 } + pub fn WEXITSTATUS(status: i32) -> i32 { status >> 8 } + pub fn WTERMSIG(status: i32) -> i32 { status & 0o177 } + } + + if imp::WIFEXITED(status) { + ExitStatus::Code(imp::WEXITSTATUS(status)) + } else { + ExitStatus::Signal(imp::WTERMSIG(status)) + } +} |