9debe91675
`Stdio` now implements `From<ChildStdin>`, `From<ChildStdout>`, `From<ChildStderr>`, and `From<File>`. The `Command::stdin`/`stdout`/`stderr` methods now take any type that implements `Into<Stdio>`. This makes it much easier to write shell-like command chains, piping to one another and redirecting to and from files. Otherwise one would need to use the unsafe and OS-specific `from_raw_fd` or `from_raw_handle`.
533 lines
17 KiB
Rust
533 lines
17 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use collections::hash_map::HashMap;
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use env;
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use ffi::OsStr;
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use fmt;
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use io::{self, Error, ErrorKind};
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use path::Path;
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use sys::fd::FileDesc;
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use sys::fs::{File, OpenOptions};
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use sys::pipe::{self, AnonPipe};
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use sys::{cvt, syscall};
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////////////////////////////////////////////////////////////////////////////////
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// Command
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////////////////////////////////////////////////////////////////////////////////
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pub struct Command {
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// Currently we try hard to ensure that the call to `.exec()` doesn't
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// actually allocate any memory. While many platforms try to ensure that
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// memory allocation works after a fork in a multithreaded process, it's
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// been observed to be buggy and somewhat unreliable, so we do our best to
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// just not do it at all!
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//
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// Along those lines, the `argv` and `envp` raw pointers here are exactly
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// what's gonna get passed to `execvp`. The `argv` array starts with the
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// `program` and ends with a NULL, and the `envp` pointer, if present, is
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// also null-terminated.
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//
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// Right now we don't support removing arguments, so there's no much fancy
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// support there, but we support adding and removing environment variables,
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// so a side table is used to track where in the `envp` array each key is
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// located. Whenever we add a key we update it in place if it's already
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// present, and whenever we remove a key we update the locations of all
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// other keys.
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program: String,
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args: Vec<String>,
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env: HashMap<String, String>,
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cwd: Option<String>,
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uid: Option<u32>,
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gid: Option<u32>,
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saw_nul: bool,
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closures: Vec<Box<FnMut() -> io::Result<()> + Send + Sync>>,
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stdin: Option<Stdio>,
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stdout: Option<Stdio>,
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stderr: Option<Stdio>,
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}
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// passed back to std::process with the pipes connected to the child, if any
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// were requested
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pub struct StdioPipes {
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pub stdin: Option<AnonPipe>,
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pub stdout: Option<AnonPipe>,
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pub stderr: Option<AnonPipe>,
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}
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// passed to do_exec() with configuration of what the child stdio should look
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// like
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struct ChildPipes {
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stdin: ChildStdio,
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stdout: ChildStdio,
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stderr: ChildStdio,
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}
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enum ChildStdio {
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Inherit,
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Explicit(usize),
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Owned(FileDesc),
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}
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pub enum Stdio {
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Inherit,
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Null,
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MakePipe,
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Fd(FileDesc),
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}
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impl Command {
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pub fn new(program: &OsStr) -> Command {
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Command {
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program: program.to_str().unwrap().to_owned(),
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args: Vec::new(),
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env: HashMap::new(),
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cwd: None,
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uid: None,
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gid: None,
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saw_nul: false,
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closures: Vec::new(),
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stdin: None,
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stdout: None,
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stderr: None,
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}
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}
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pub fn arg(&mut self, arg: &OsStr) {
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self.args.push(arg.to_str().unwrap().to_owned());
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}
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pub fn env(&mut self, key: &OsStr, val: &OsStr) {
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self.env.insert(key.to_str().unwrap().to_owned(), val.to_str().unwrap().to_owned());
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}
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pub fn env_remove(&mut self, key: &OsStr) {
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self.env.remove(key.to_str().unwrap());
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}
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pub fn env_clear(&mut self) {
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self.env.clear();
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}
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pub fn cwd(&mut self, dir: &OsStr) {
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self.cwd = Some(dir.to_str().unwrap().to_owned());
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}
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pub fn uid(&mut self, id: u32) {
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self.uid = Some(id);
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}
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pub fn gid(&mut self, id: u32) {
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self.gid = Some(id);
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}
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pub fn before_exec(&mut self,
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f: Box<FnMut() -> io::Result<()> + Send + Sync>) {
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self.closures.push(f);
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}
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pub fn stdin(&mut self, stdin: Stdio) {
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self.stdin = Some(stdin);
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}
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pub fn stdout(&mut self, stdout: Stdio) {
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self.stdout = Some(stdout);
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}
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pub fn stderr(&mut self, stderr: Stdio) {
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self.stderr = Some(stderr);
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}
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pub fn spawn(&mut self, default: Stdio, needs_stdin: bool)
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-> io::Result<(Process, StdioPipes)> {
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const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX";
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if self.saw_nul {
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return Err(io::Error::new(ErrorKind::InvalidInput,
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"nul byte found in provided data"));
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}
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let (ours, theirs) = self.setup_io(default, needs_stdin)?;
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let (input, output) = pipe::anon_pipe()?;
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let pid = unsafe {
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match cvt(syscall::clone(0))? {
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0 => {
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drop(input);
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let err = self.do_exec(theirs);
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let errno = err.raw_os_error().unwrap_or(syscall::EINVAL) as u32;
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let bytes = [
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(errno >> 24) as u8,
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(errno >> 16) as u8,
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(errno >> 8) as u8,
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(errno >> 0) as u8,
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CLOEXEC_MSG_FOOTER[0], CLOEXEC_MSG_FOOTER[1],
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CLOEXEC_MSG_FOOTER[2], CLOEXEC_MSG_FOOTER[3]
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];
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// pipe I/O up to PIPE_BUF bytes should be atomic, and then
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// we want to be sure we *don't* run at_exit destructors as
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// we're being torn down regardless
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assert!(output.write(&bytes).is_ok());
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let _ = syscall::exit(1);
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panic!("failed to exit");
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}
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n => n,
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}
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};
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let mut p = Process { pid: pid, status: None };
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drop(output);
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let mut bytes = [0; 8];
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// loop to handle EINTR
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loop {
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match input.read(&mut bytes) {
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Ok(0) => return Ok((p, ours)),
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Ok(8) => {
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assert!(combine(CLOEXEC_MSG_FOOTER) == combine(&bytes[4.. 8]),
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"Validation on the CLOEXEC pipe failed: {:?}", bytes);
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let errno = combine(&bytes[0.. 4]);
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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return Err(Error::from_raw_os_error(errno))
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}
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Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
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Err(e) => {
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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panic!("the CLOEXEC pipe failed: {:?}", e)
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},
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Ok(..) => { // pipe I/O up to PIPE_BUF bytes should be atomic
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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panic!("short read on the CLOEXEC pipe")
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}
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}
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}
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fn combine(arr: &[u8]) -> i32 {
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let a = arr[0] as u32;
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let b = arr[1] as u32;
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let c = arr[2] as u32;
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let d = arr[3] as u32;
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((a << 24) | (b << 16) | (c << 8) | (d << 0)) as i32
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}
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}
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pub fn exec(&mut self, default: Stdio) -> io::Error {
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if self.saw_nul {
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return io::Error::new(ErrorKind::InvalidInput,
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"nul byte found in provided data")
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}
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match self.setup_io(default, true) {
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Ok((_, theirs)) => unsafe { self.do_exec(theirs) },
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Err(e) => e,
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}
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}
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// And at this point we've reached a special time in the life of the
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// child. The child must now be considered hamstrung and unable to
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// do anything other than syscalls really. Consider the following
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// scenario:
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//
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// 1. Thread A of process 1 grabs the malloc() mutex
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// 2. Thread B of process 1 forks(), creating thread C
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// 3. Thread C of process 2 then attempts to malloc()
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// 4. The memory of process 2 is the same as the memory of
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// process 1, so the mutex is locked.
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//
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// This situation looks a lot like deadlock, right? It turns out
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// that this is what pthread_atfork() takes care of, which is
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// presumably implemented across platforms. The first thing that
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// threads to *before* forking is to do things like grab the malloc
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// mutex, and then after the fork they unlock it.
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//
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// Despite this information, libnative's spawn has been witnessed to
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// deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
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// all collected backtraces point at malloc/free traffic in the
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// child spawned process.
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//
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// For this reason, the block of code below should contain 0
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// invocations of either malloc of free (or their related friends).
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//
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// As an example of not having malloc/free traffic, we don't close
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// this file descriptor by dropping the FileDesc (which contains an
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// allocation). Instead we just close it manually. This will never
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// have the drop glue anyway because this code never returns (the
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// child will either exec() or invoke syscall::exit)
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unsafe fn do_exec(&mut self, stdio: ChildPipes) -> io::Error {
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macro_rules! t {
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($e:expr) => (match $e {
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Ok(e) => e,
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Err(e) => return e,
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})
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}
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if let Some(fd) = stdio.stderr.fd() {
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t!(cvt(syscall::dup2(fd, 2, &[])));
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let mut flags = t!(cvt(syscall::fcntl(2, syscall::F_GETFL, 0)));
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flags &= ! syscall::O_CLOEXEC;
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t!(cvt(syscall::fcntl(2, syscall::F_SETFL, flags)));
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}
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if let Some(fd) = stdio.stdout.fd() {
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t!(cvt(syscall::dup2(fd, 1, &[])));
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let mut flags = t!(cvt(syscall::fcntl(1, syscall::F_GETFL, 0)));
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flags &= ! syscall::O_CLOEXEC;
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t!(cvt(syscall::fcntl(1, syscall::F_SETFL, flags)));
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}
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if let Some(fd) = stdio.stdin.fd() {
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t!(cvt(syscall::dup2(fd, 0, &[])));
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let mut flags = t!(cvt(syscall::fcntl(0, syscall::F_GETFL, 0)));
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flags &= ! syscall::O_CLOEXEC;
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t!(cvt(syscall::fcntl(0, syscall::F_SETFL, flags)));
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}
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if let Some(g) = self.gid {
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t!(cvt(syscall::setregid(g as usize, g as usize)));
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}
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if let Some(u) = self.uid {
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t!(cvt(syscall::setreuid(u as usize, u as usize)));
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}
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if let Some(ref cwd) = self.cwd {
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t!(cvt(syscall::chdir(cwd)));
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}
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for callback in self.closures.iter_mut() {
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t!(callback());
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}
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let mut args: Vec<[usize; 2]> = Vec::new();
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args.push([self.program.as_ptr() as usize, self.program.len()]);
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for arg in self.args.iter() {
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args.push([arg.as_ptr() as usize, arg.len()]);
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}
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for (key, val) in self.env.iter() {
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env::set_var(key, val);
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}
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let program = if self.program.contains(':') || self.program.contains('/') {
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self.program.to_owned()
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} else {
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let mut path_env = ::env::var("PATH").unwrap_or(".".to_string());
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if ! path_env.ends_with('/') {
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path_env.push('/');
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}
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path_env.push_str(&self.program);
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path_env
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};
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if let Err(err) = syscall::execve(&program, &args) {
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io::Error::from_raw_os_error(err.errno as i32)
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} else {
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panic!("return from exec without err");
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}
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}
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fn setup_io(&self, default: Stdio, needs_stdin: bool)
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-> io::Result<(StdioPipes, ChildPipes)> {
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let null = Stdio::Null;
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let default_stdin = if needs_stdin {&default} else {&null};
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let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
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let stdout = self.stdout.as_ref().unwrap_or(&default);
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let stderr = self.stderr.as_ref().unwrap_or(&default);
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let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
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let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
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let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
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let ours = StdioPipes {
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stdin: our_stdin,
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stdout: our_stdout,
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stderr: our_stderr,
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};
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let theirs = ChildPipes {
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stdin: their_stdin,
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stdout: their_stdout,
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stderr: their_stderr,
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};
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Ok((ours, theirs))
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}
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}
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impl Stdio {
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fn to_child_stdio(&self, readable: bool)
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-> io::Result<(ChildStdio, Option<AnonPipe>)> {
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match *self {
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Stdio::Inherit => Ok((ChildStdio::Inherit, None)),
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// Make sure that the source descriptors are not an stdio
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// descriptor, otherwise the order which we set the child's
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// descriptors may blow away a descriptor which we are hoping to
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// save. For example, suppose we want the child's stderr to be the
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// parent's stdout, and the child's stdout to be the parent's
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// stderr. No matter which we dup first, the second will get
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// overwritten prematurely.
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Stdio::Fd(ref fd) => {
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if fd.raw() <= 2 {
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Ok((ChildStdio::Owned(fd.duplicate()?), None))
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} else {
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Ok((ChildStdio::Explicit(fd.raw()), None))
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}
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}
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Stdio::MakePipe => {
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let (reader, writer) = pipe::anon_pipe()?;
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let (ours, theirs) = if readable {
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(writer, reader)
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} else {
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(reader, writer)
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};
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Ok((ChildStdio::Owned(theirs.into_fd()), Some(ours)))
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}
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Stdio::Null => {
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let mut opts = OpenOptions::new();
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opts.read(readable);
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opts.write(!readable);
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let fd = File::open(&Path::new("null:"), &opts)?;
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Ok((ChildStdio::Owned(fd.into_fd()), None))
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}
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}
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}
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}
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impl From<AnonPipe> for Stdio {
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fn from(pipe: AnonPipe) -> Stdio {
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Stdio::Fd(pipe.into_fd())
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}
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}
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impl From<File> for Stdio {
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fn from(file: File) -> Stdio {
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Stdio::Fd(file.into_fd())
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}
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}
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impl ChildStdio {
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fn fd(&self) -> Option<usize> {
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match *self {
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ChildStdio::Inherit => None,
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ChildStdio::Explicit(fd) => Some(fd),
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ChildStdio::Owned(ref fd) => Some(fd.raw()),
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}
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}
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}
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impl fmt::Debug for Command {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{:?}", self.program)?;
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for arg in &self.args {
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write!(f, " {:?}", arg)?;
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}
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Ok(())
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}
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}
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////////////////////////////////////////////////////////////////////////////////
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// Processes
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////////////////////////////////////////////////////////////////////////////////
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|
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/// Unix exit statuses
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#[derive(PartialEq, Eq, Clone, Copy, Debug)]
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pub struct ExitStatus(i32);
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impl ExitStatus {
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fn exited(&self) -> bool {
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self.0 & 0x7F == 0
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}
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pub fn success(&self) -> bool {
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self.code() == Some(0)
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}
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pub fn code(&self) -> Option<i32> {
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if self.exited() {
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Some((self.0 >> 8) & 0xFF)
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} else {
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None
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}
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}
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pub fn signal(&self) -> Option<i32> {
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if !self.exited() {
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Some(self.0 & 0x7F)
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} else {
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None
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}
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}
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}
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impl From<i32> for ExitStatus {
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fn from(a: i32) -> ExitStatus {
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ExitStatus(a)
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}
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}
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impl fmt::Display for ExitStatus {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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if let Some(code) = self.code() {
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write!(f, "exit code: {}", code)
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} else {
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let signal = self.signal().unwrap();
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write!(f, "signal: {}", signal)
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}
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}
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}
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|
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/// The unique id of the process (this should never be negative).
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pub struct Process {
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pid: usize,
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status: Option<ExitStatus>,
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}
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impl Process {
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pub fn id(&self) -> u32 {
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self.pid as u32
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}
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pub fn kill(&mut self) -> io::Result<()> {
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// If we've already waited on this process then the pid can be recycled
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// and used for another process, and we probably shouldn't be killing
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// random processes, so just return an error.
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if self.status.is_some() {
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Err(Error::new(ErrorKind::InvalidInput,
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"invalid argument: can't kill an exited process"))
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} else {
|
|
cvt(syscall::kill(self.pid, syscall::SIGKILL))?;
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
pub fn wait(&mut self) -> io::Result<ExitStatus> {
|
|
if let Some(status) = self.status {
|
|
return Ok(status)
|
|
}
|
|
let mut status = 0;
|
|
cvt(syscall::waitpid(self.pid, &mut status, 0))?;
|
|
self.status = Some(ExitStatus(status as i32));
|
|
Ok(ExitStatus(status as i32))
|
|
}
|
|
|
|
pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
|
|
if let Some(status) = self.status {
|
|
return Ok(Some(status))
|
|
}
|
|
let mut status = 0;
|
|
let pid = cvt(syscall::waitpid(self.pid, &mut status, syscall::WNOHANG))?;
|
|
if pid == 0 {
|
|
Ok(None)
|
|
} else {
|
|
self.status = Some(ExitStatus(status as i32));
|
|
Ok(Some(ExitStatus(status as i32)))
|
|
}
|
|
}
|
|
}
|