| use crate::env::{self, split_paths}; |
| use crate::ffi::{CStr, OsStr}; |
| use crate::fmt; |
| use crate::fs::File; |
| use crate::io::{self, prelude::*, BufReader, Error, ErrorKind, SeekFrom}; |
| use crate::os::unix::ffi::OsStrExt; |
| use crate::path::{Path, PathBuf}; |
| use crate::ptr; |
| use crate::sys::ext::fs::MetadataExt; |
| use crate::sys::ext::io::AsRawFd; |
| use crate::sys::fd::FileDesc; |
| use crate::sys::fs::{File as SysFile, OpenOptions}; |
| use crate::sys::os::{ENV_LOCK, environ}; |
| use crate::sys::pipe::{self, AnonPipe}; |
| use crate::sys::{cvt, syscall}; |
| use crate::sys_common::process::{CommandEnv, DefaultEnvKey}; |
| |
| use libc::{EXIT_SUCCESS, EXIT_FAILURE}; |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Command |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| pub struct Command { |
| // Currently we try hard to ensure that the call to `.exec()` doesn't |
| // actually allocate any memory. While many platforms try to ensure that |
| // memory allocation works after a fork in a multithreaded process, it's |
| // been observed to be buggy and somewhat unreliable, so we do our best to |
| // just not do it at all! |
| // |
| // Along those lines, the `argv` and `envp` raw pointers here are exactly |
| // what's gonna get passed to `execvp`. The `argv` array starts with the |
| // `program` and ends with a NULL, and the `envp` pointer, if present, is |
| // also null-terminated. |
| // |
| // Right now we don't support removing arguments, so there's no much fancy |
| // support there, but we support adding and removing environment variables, |
| // so a side table is used to track where in the `envp` array each key is |
| // located. Whenever we add a key we update it in place if it's already |
| // present, and whenever we remove a key we update the locations of all |
| // other keys. |
| program: String, |
| args: Vec<String>, |
| env: CommandEnv<DefaultEnvKey>, |
| |
| cwd: Option<String>, |
| uid: Option<u32>, |
| gid: Option<u32>, |
| saw_nul: bool, |
| closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>, |
| stdin: Option<Stdio>, |
| stdout: Option<Stdio>, |
| stderr: Option<Stdio>, |
| } |
| |
| // passed back to std::process with the pipes connected to the child, if any |
| // were requested |
| pub struct StdioPipes { |
| pub stdin: Option<AnonPipe>, |
| pub stdout: Option<AnonPipe>, |
| pub stderr: Option<AnonPipe>, |
| } |
| |
| // passed to do_exec() with configuration of what the child stdio should look |
| // like |
| struct ChildPipes { |
| stdin: ChildStdio, |
| stdout: ChildStdio, |
| stderr: ChildStdio, |
| } |
| |
| enum ChildStdio { |
| Inherit, |
| Explicit(usize), |
| Owned(FileDesc), |
| } |
| |
| pub enum Stdio { |
| Inherit, |
| Null, |
| MakePipe, |
| Fd(FileDesc), |
| } |
| |
| impl Command { |
| pub fn new(program: &OsStr) -> Command { |
| Command { |
| program: program.to_str().unwrap().to_owned(), |
| args: Vec::new(), |
| env: Default::default(), |
| cwd: None, |
| uid: None, |
| gid: None, |
| saw_nul: false, |
| closures: Vec::new(), |
| stdin: None, |
| stdout: None, |
| stderr: None, |
| } |
| } |
| |
| pub fn arg(&mut self, arg: &OsStr) { |
| self.args.push(arg.to_str().unwrap().to_owned()); |
| } |
| |
| pub fn env_mut(&mut self) -> &mut CommandEnv<DefaultEnvKey> { |
| &mut self.env |
| } |
| |
| pub fn cwd(&mut self, dir: &OsStr) { |
| self.cwd = Some(dir.to_str().unwrap().to_owned()); |
| } |
| pub fn uid(&mut self, id: u32) { |
| self.uid = Some(id); |
| } |
| pub fn gid(&mut self, id: u32) { |
| self.gid = Some(id); |
| } |
| |
| pub unsafe fn pre_exec( |
| &mut self, |
| f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>, |
| ) { |
| self.closures.push(f); |
| } |
| |
| pub fn stdin(&mut self, stdin: Stdio) { |
| self.stdin = Some(stdin); |
| } |
| pub fn stdout(&mut self, stdout: Stdio) { |
| self.stdout = Some(stdout); |
| } |
| pub fn stderr(&mut self, stderr: Stdio) { |
| self.stderr = Some(stderr); |
| } |
| |
| pub fn spawn(&mut self, default: Stdio, needs_stdin: bool) |
| -> io::Result<(Process, StdioPipes)> { |
| const CLOEXEC_MSG_FOOTER: &[u8] = b"NOEX"; |
| |
| 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)?; |
| let (input, output) = pipe::anon_pipe()?; |
| |
| let pid = unsafe { |
| match cvt(syscall::clone(0))? { |
| 0 => { |
| drop(input); |
| let err = self.do_exec(theirs); |
| let errno = err.raw_os_error().unwrap_or(syscall::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()); |
| let _ = syscall::exit(1); |
| panic!("failed to exit"); |
| } |
| 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 { |
| 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) }, |
| 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 syscall::exit) |
| unsafe fn do_exec(&mut self, stdio: ChildPipes) -> io::Error { |
| macro_rules! t { |
| ($e:expr) => (match $e { |
| Ok(e) => e, |
| Err(e) => return e, |
| }) |
| } |
| |
| if let Some(fd) = stdio.stderr.fd() { |
| t!(cvt(syscall::dup2(fd, 2, &[]))); |
| let mut flags = t!(cvt(syscall::fcntl(2, syscall::F_GETFD, 0))); |
| flags &= ! syscall::O_CLOEXEC; |
| t!(cvt(syscall::fcntl(2, syscall::F_SETFD, flags))); |
| } |
| if let Some(fd) = stdio.stdout.fd() { |
| t!(cvt(syscall::dup2(fd, 1, &[]))); |
| let mut flags = t!(cvt(syscall::fcntl(1, syscall::F_GETFD, 0))); |
| flags &= ! syscall::O_CLOEXEC; |
| t!(cvt(syscall::fcntl(1, syscall::F_SETFD, flags))); |
| } |
| if let Some(fd) = stdio.stdin.fd() { |
| t!(cvt(syscall::dup2(fd, 0, &[]))); |
| let mut flags = t!(cvt(syscall::fcntl(0, syscall::F_GETFD, 0))); |
| flags &= ! syscall::O_CLOEXEC; |
| t!(cvt(syscall::fcntl(0, syscall::F_SETFD, flags))); |
| } |
| |
| if let Some(g) = self.gid { |
| t!(cvt(syscall::setregid(g as usize, g as usize))); |
| } |
| if let Some(u) = self.uid { |
| t!(cvt(syscall::setreuid(u as usize, u as usize))); |
| } |
| if let Some(ref cwd) = self.cwd { |
| t!(cvt(syscall::chdir(cwd))); |
| } |
| |
| for callback in self.closures.iter_mut() { |
| t!(callback()); |
| } |
| |
| self.env.apply(); |
| |
| let program = if self.program.contains(':') || self.program.contains('/') { |
| Some(PathBuf::from(&self.program)) |
| } else if let Ok(path_env) = env::var("PATH") { |
| let mut program = None; |
| for mut path in split_paths(&path_env) { |
| path.push(&self.program); |
| if path.exists() { |
| program = Some(path); |
| break; |
| } |
| } |
| program |
| } else { |
| None |
| }; |
| |
| let mut file = if let Some(program) = program { |
| t!(File::open(program.as_os_str())) |
| } else { |
| return io::Error::from_raw_os_error(syscall::ENOENT); |
| }; |
| |
| // Push all the arguments |
| let mut args: Vec<[usize; 2]> = Vec::with_capacity(1 + self.args.len()); |
| |
| let interpreter = { |
| let mut reader = BufReader::new(&file); |
| |
| let mut shebang = [0; 2]; |
| let mut read = 0; |
| loop { |
| match t!(reader.read(&mut shebang[read..])) { |
| 0 => break, |
| n => read += n, |
| } |
| } |
| |
| if &shebang == b"#!" { |
| // This is an interpreted script. |
| // First of all, since we'll be passing another file to |
| // fexec(), we need to manually check that we have permission |
| // to execute this file: |
| let uid = t!(cvt(syscall::getuid())); |
| let gid = t!(cvt(syscall::getgid())); |
| let meta = t!(file.metadata()); |
| |
| let mode = if uid == meta.uid() as usize { |
| meta.mode() >> 3*2 & 0o7 |
| } else if gid == meta.gid() as usize { |
| meta.mode() >> 3*1 & 0o7 |
| } else { |
| meta.mode() & 0o7 |
| }; |
| if mode & 1 == 0 { |
| return io::Error::from_raw_os_error(syscall::EPERM); |
| } |
| |
| // Second of all, we need to actually read which interpreter it wants |
| let mut interpreter = Vec::new(); |
| t!(reader.read_until(b'\n', &mut interpreter)); |
| // Pop one trailing newline, if any |
| if interpreter.ends_with(&[b'\n']) { |
| interpreter.pop().unwrap(); |
| } |
| |
| // FIXME: Here we could just reassign `file` directly, if it |
| // wasn't for lexical lifetimes. Remove the whole `let |
| // interpreter = { ... };` hack once NLL lands. |
| // NOTE: Although DO REMEMBER to make sure the interpreter path |
| // still lives long enough to reach fexec. |
| Some(interpreter) |
| } else { |
| None |
| } |
| }; |
| if let Some(ref interpreter) = interpreter { |
| let path: &OsStr = OsStr::from_bytes(&interpreter); |
| file = t!(File::open(path)); |
| |
| args.push([interpreter.as_ptr() as usize, interpreter.len()]); |
| } else { |
| t!(file.seek(SeekFrom::Start(0))); |
| } |
| |
| args.push([self.program.as_ptr() as usize, self.program.len()]); |
| args.extend(self.args.iter().map(|arg| [arg.as_ptr() as usize, arg.len()])); |
| |
| // Push all the variables |
| let mut vars: Vec<[usize; 2]> = Vec::new(); |
| { |
| let _guard = ENV_LOCK.lock(); |
| let mut environ = *environ(); |
| while *environ != ptr::null() { |
| let var = CStr::from_ptr(*environ).to_bytes(); |
| vars.push([var.as_ptr() as usize, var.len()]); |
| environ = environ.offset(1); |
| } |
| } |
| |
| if let Err(err) = syscall::fexec(file.as_raw_fd(), &args, &vars) { |
| io::Error::from_raw_os_error(err.errno as i32) |
| } else { |
| panic!("return from exec without err"); |
| } |
| } |
| |
| |
| fn setup_io(&self, default: Stdio, needs_stdin: bool) |
| -> io::Result<(StdioPipes, ChildPipes)> { |
| let null = Stdio::Null; |
| let default_stdin = if needs_stdin {&default} else {&null}; |
| let stdin = self.stdin.as_ref().unwrap_or(default_stdin); |
| let stdout = self.stdout.as_ref().unwrap_or(&default); |
| let stderr = self.stderr.as_ref().unwrap_or(&default); |
| let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?; |
| let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?; |
| let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?; |
| let ours = StdioPipes { |
| stdin: our_stdin, |
| stdout: our_stdout, |
| stderr: our_stderr, |
| }; |
| let theirs = ChildPipes { |
| stdin: their_stdin, |
| stdout: their_stdout, |
| stderr: their_stderr, |
| }; |
| Ok((ours, theirs)) |
| } |
| } |
| |
| impl Stdio { |
| fn to_child_stdio(&self, readable: bool) |
| -> io::Result<(ChildStdio, Option<AnonPipe>)> { |
| match *self { |
| Stdio::Inherit => Ok((ChildStdio::Inherit, None)), |
| |
| // Make sure that the source descriptors are not an stdio |
| // descriptor, otherwise the order which we set the child's |
| // descriptors may blow away a descriptor which we are hoping to |
| // save. For example, suppose we want the child's stderr to be the |
| // parent's stdout, and the child's stdout to be the parent's |
| // stderr. No matter which we dup first, the second will get |
| // overwritten prematurely. |
| Stdio::Fd(ref fd) => { |
| if fd.raw() <= 2 { |
| Ok((ChildStdio::Owned(fd.duplicate()?), None)) |
| } else { |
| Ok((ChildStdio::Explicit(fd.raw()), None)) |
| } |
| } |
| |
| Stdio::MakePipe => { |
| let (reader, writer) = pipe::anon_pipe()?; |
| let (ours, theirs) = if readable { |
| (writer, reader) |
| } else { |
| (reader, writer) |
| }; |
| Ok((ChildStdio::Owned(theirs.into_fd()), Some(ours))) |
| } |
| |
| Stdio::Null => { |
| let mut opts = OpenOptions::new(); |
| opts.read(readable); |
| opts.write(!readable); |
| let fd = SysFile::open(Path::new("null:"), &opts)?; |
| Ok((ChildStdio::Owned(fd.into_fd()), None)) |
| } |
| } |
| } |
| } |
| |
| impl From<AnonPipe> for Stdio { |
| fn from(pipe: AnonPipe) -> Stdio { |
| Stdio::Fd(pipe.into_fd()) |
| } |
| } |
| |
| impl From<SysFile> for Stdio { |
| fn from(file: SysFile) -> Stdio { |
| Stdio::Fd(file.into_fd()) |
| } |
| } |
| |
| impl ChildStdio { |
| fn fd(&self) -> Option<usize> { |
| match *self { |
| ChildStdio::Inherit => None, |
| ChildStdio::Explicit(fd) => Some(fd), |
| ChildStdio::Owned(ref fd) => Some(fd.raw()), |
| } |
| } |
| } |
| |
| impl fmt::Debug for Command { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "{:?}", self.program)?; |
| for arg in &self.args { |
| write!(f, " {:?}", arg)?; |
| } |
| Ok(()) |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Processes |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| /// Unix exit statuses |
| #[derive(PartialEq, Eq, Clone, Copy, Debug)] |
| pub struct ExitStatus(i32); |
| |
| impl ExitStatus { |
| fn exited(&self) -> bool { |
| self.0 & 0x7F == 0 |
| } |
| |
| pub fn success(&self) -> bool { |
| self.code() == Some(0) |
| } |
| |
| pub fn code(&self) -> Option<i32> { |
| if self.exited() { |
| Some((self.0 >> 8) & 0xFF) |
| } else { |
| None |
| } |
| } |
| |
| pub fn signal(&self) -> Option<i32> { |
| if !self.exited() { |
| Some(self.0 & 0x7F) |
| } else { |
| None |
| } |
| } |
| } |
| |
| impl From<i32> for ExitStatus { |
| fn from(a: i32) -> 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) |
| } |
| } |
| } |
| |
| #[derive(PartialEq, Eq, Clone, Copy, Debug)] |
| pub struct ExitCode(u8); |
| |
| impl ExitCode { |
| pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _); |
| pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _); |
| |
| pub fn as_i32(&self) -> i32 { |
| self.0 as i32 |
| } |
| } |
| |
| /// The unique ID of the process (this should never be negative). |
| pub struct Process { |
| pid: usize, |
| 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(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))) |
| } |
| } |
| } |