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//! Unix-specific extensions to primitives in the [`std::process`] module.
//!
//! [`std::process`]: crate::process
#![stable(feature = "rust1", since = "1.0.0")]
use crate::ffi::OsStr;
use crate::io;
use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
use crate::process;
use crate::sealed::Sealed;
use crate::sys;
use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
#[cfg(not(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon")))]
type UserId = u32;
#[cfg(not(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon")))]
type GroupId = u32;
#[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon"))]
type UserId = u16;
#[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon"))]
type GroupId = u16;
/// Unix-specific extensions to the [`process::Command`] builder.
///
/// This trait is sealed: it cannot be implemented outside the standard library.
/// This is so that future additional methods are not breaking changes.
#[stable(feature = "rust1", since = "1.0.0")]
pub trait CommandExt: Sealed {
/// Sets the child process's user ID. This translates to a
/// `setuid` call in the child process. Failure in the `setuid`
/// call will cause the spawn to fail.
#[stable(feature = "rust1", since = "1.0.0")]
fn uid(&mut self, id: UserId) -> &mut process::Command;
/// Similar to `uid`, but sets the group ID of the child process. This has
/// the same semantics as the `uid` field.
#[stable(feature = "rust1", since = "1.0.0")]
fn gid(&mut self, id: GroupId) -> &mut process::Command;
/// Sets the supplementary group IDs for the calling process. Translates to
/// a `setgroups` call in the child process.
#[unstable(feature = "setgroups", issue = "90747")]
fn groups(&mut self, groups: &[GroupId]) -> &mut process::Command;
/// Schedules a closure to be run just before the `exec` function is
/// invoked.
///
/// The closure is allowed to return an I/O error whose OS error code will
/// be communicated back to the parent and returned as an error from when
/// the spawn was requested.
///
/// Multiple closures can be registered and they will be called in order of
/// their registration. If a closure returns `Err` then no further closures
/// will be called and the spawn operation will immediately return with a
/// failure.
///
/// # Notes and Safety
///
/// This closure will be run in the context of the child process after a
/// `fork`. This primarily means that any modifications made to memory on
/// behalf of this closure will **not** be visible to the parent process.
/// This is often a very constrained environment where normal operations
/// like `malloc`, accessing environment variables through [`std::env`]
/// or acquiring a mutex are not guaranteed to work (due to
/// other threads perhaps still running when the `fork` was run).
///
/// For further details refer to the [POSIX fork() specification]
/// and the equivalent documentation for any targeted
/// platform, especially the requirements around *async-signal-safety*.
///
/// This also means that all resources such as file descriptors and
/// memory-mapped regions got duplicated. It is your responsibility to make
/// sure that the closure does not violate library invariants by making
/// invalid use of these duplicates.
///
/// Panicking in the closure is safe only if all the format arguments for the
/// panic message can be safely formatted; this is because although
/// `Command` calls [`std::panic::always_abort`](crate::panic::always_abort)
/// before calling the pre_exec hook, panic will still try to format the
/// panic message.
///
/// When this closure is run, aspects such as the stdio file descriptors and
/// working directory have successfully been changed, so output to these
/// locations might not appear where intended.
///
/// [POSIX fork() specification]:
/// https://pubs.opengroup.org/onlinepubs/9699919799/functions/fork.html
/// [`std::env`]: mod@crate::env
#[stable(feature = "process_pre_exec", since = "1.34.0")]
unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
where
F: FnMut() -> io::Result<()> + Send + Sync + 'static;
/// Schedules a closure to be run just before the `exec` function is
/// invoked.
///
/// This method is stable and usable, but it should be unsafe. To fix
/// that, it got deprecated in favor of the unsafe [`pre_exec`].
///
/// [`pre_exec`]: CommandExt::pre_exec
#[stable(feature = "process_exec", since = "1.15.0")]
#[deprecated(since = "1.37.0", note = "should be unsafe, use `pre_exec` instead")]
fn before_exec<F>(&mut self, f: F) -> &mut process::Command
where
F: FnMut() -> io::Result<()> + Send + Sync + 'static,
{
unsafe { self.pre_exec(f) }
}
/// Performs all the required setup by this `Command`, followed by calling
/// the `execvp` syscall.
///
/// On success this function will not return, and otherwise it will return
/// an error indicating why the exec (or another part of the setup of the
/// `Command`) failed.
///
/// `exec` not returning has the same implications as calling
/// [`process::exit`] – no destructors on the current stack or any other
/// thread’s stack will be run. Therefore, it is recommended to only call
/// `exec` at a point where it is fine to not run any destructors. Note,
/// that the `execvp` syscall independently guarantees that all memory is
/// freed and all file descriptors with the `CLOEXEC` option (set by default
/// on all file descriptors opened by the standard library) are closed.
///
/// This function, unlike `spawn`, will **not** `fork` the process to create
/// a new child. Like spawn, however, the default behavior for the stdio
/// descriptors will be to inherited from the current process.
///
/// # Notes
///
/// The process may be in a "broken state" if this function returns in
/// error. For example the working directory, environment variables, signal
/// handling settings, various user/group information, or aspects of stdio
/// file descriptors may have changed. If a "transactional spawn" is
/// required to gracefully handle errors it is recommended to use the
/// cross-platform `spawn` instead.
#[stable(feature = "process_exec2", since = "1.9.0")]
fn exec(&mut self) -> io::Error;
/// Set executable argument
///
/// Set the first process argument, `argv[0]`, to something other than the
/// default executable path.
#[stable(feature = "process_set_argv0", since = "1.45.0")]
fn arg0<S>(&mut self, arg: S) -> &mut process::Command
where
S: AsRef<OsStr>;
/// Sets the process group ID (PGID) of the child process. Equivalent to a
/// `setpgid` call in the child process, but may be more efficient.
///
/// Process groups determine which processes receive signals.
///
/// # Examples
///
/// Pressing Ctrl-C in a terminal will send SIGINT to all processes in
/// the current foreground process group. By spawning the `sleep`
/// subprocess in a new process group, it will not receive SIGINT from the
/// terminal.
///
/// The parent process could install a signal handler and manage the
/// subprocess on its own terms.
///
/// A process group ID of 0 will use the process ID as the PGID.
///
/// ```no_run
/// use std::process::Command;
/// use std::os::unix::process::CommandExt;
///
/// Command::new("sleep")
/// .arg("10")
/// .process_group(0)
/// .spawn()?
/// .wait()?;
/// #
/// # Ok::<_, Box<dyn std::error::Error>>(())
/// ```
#[stable(feature = "process_set_process_group", since = "1.64.0")]
fn process_group(&mut self, pgroup: i32) -> &mut process::Command;
}
#[stable(feature = "rust1", since = "1.0.0")]
impl CommandExt for process::Command {
fn uid(&mut self, id: UserId) -> &mut process::Command {
self.as_inner_mut().uid(id);
self
}
fn gid(&mut self, id: GroupId) -> &mut process::Command {
self.as_inner_mut().gid(id);
self
}
fn groups(&mut self, groups: &[GroupId]) -> &mut process::Command {
self.as_inner_mut().groups(groups);
self
}
unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
where
F: FnMut() -> io::Result<()> + Send + Sync + 'static,
{
self.as_inner_mut().pre_exec(Box::new(f));
self
}
fn exec(&mut self) -> io::Error {
// NOTE: This may *not* be safe to call after `libc::fork`, because it
// may allocate. That may be worth fixing at some point in the future.
self.as_inner_mut().exec(sys::process::Stdio::Inherit)
}
fn arg0<S>(&mut self, arg: S) -> &mut process::Command
where
S: AsRef<OsStr>,
{
self.as_inner_mut().set_arg_0(arg.as_ref());
self
}
fn process_group(&mut self, pgroup: i32) -> &mut process::Command {
self.as_inner_mut().pgroup(pgroup);
self
}
}
/// Unix-specific extensions to [`process::ExitStatus`] and
/// [`ExitStatusError`](process::ExitStatusError).
///
/// On Unix, `ExitStatus` **does not necessarily represent an exit status**, as
/// passed to the `_exit` system call or returned by
/// [`ExitStatus::code()`](crate::process::ExitStatus::code). It represents **any wait status**
/// as returned by one of the `wait` family of system
/// calls.
///
/// A Unix wait status (a Rust `ExitStatus`) can represent a Unix exit status, but can also
/// represent other kinds of process event.
///
/// This trait is sealed: it cannot be implemented outside the standard library.
/// This is so that future additional methods are not breaking changes.
#[stable(feature = "rust1", since = "1.0.0")]
pub trait ExitStatusExt: Sealed {
/// Creates a new `ExitStatus` or `ExitStatusError` from the raw underlying integer status
/// value from `wait`
///
/// The value should be a **wait status, not an exit status**.
///
/// # Panics
///
/// Panics on an attempt to make an `ExitStatusError` from a wait status of `0`.
///
/// Making an `ExitStatus` always succeeds and never panics.
#[stable(feature = "exit_status_from", since = "1.12.0")]
fn from_raw(raw: i32) -> Self;
/// If the process was terminated by a signal, returns that signal.
///
/// In other words, if `WIFSIGNALED`, this returns `WTERMSIG`.
#[stable(feature = "rust1", since = "1.0.0")]
fn signal(&self) -> Option<i32>;
/// If the process was terminated by a signal, says whether it dumped core.
#[stable(feature = "unix_process_wait_more", since = "1.58.0")]
fn core_dumped(&self) -> bool;
/// If the process was stopped by a signal, returns that signal.
///
/// In other words, if `WIFSTOPPED`, this returns `WSTOPSIG`. This is only possible if the status came from
/// a `wait` system call which was passed `WUNTRACED`, and was then converted into an `ExitStatus`.
#[stable(feature = "unix_process_wait_more", since = "1.58.0")]
fn stopped_signal(&self) -> Option<i32>;
/// Whether the process was continued from a stopped status.
///
/// Ie, `WIFCONTINUED`. This is only possible if the status came from a `wait` system call
/// which was passed `WCONTINUED`, and was then converted into an `ExitStatus`.
#[stable(feature = "unix_process_wait_more", since = "1.58.0")]
fn continued(&self) -> bool;
/// Returns the underlying raw `wait` status.
///
/// The returned integer is a **wait status, not an exit status**.
#[stable(feature = "unix_process_wait_more", since = "1.58.0")]
fn into_raw(self) -> i32;
}
#[stable(feature = "rust1", since = "1.0.0")]
impl ExitStatusExt for process::ExitStatus {
fn from_raw(raw: i32) -> Self {
process::ExitStatus::from_inner(From::from(raw))
}
fn signal(&self) -> Option<i32> {
self.as_inner().signal()
}
fn core_dumped(&self) -> bool {
self.as_inner().core_dumped()
}
fn stopped_signal(&self) -> Option<i32> {
self.as_inner().stopped_signal()
}
fn continued(&self) -> bool {
self.as_inner().continued()
}
fn into_raw(self) -> i32 {
self.as_inner().into_raw().into()
}
}
#[unstable(feature = "exit_status_error", issue = "84908")]
impl ExitStatusExt for process::ExitStatusError {
fn from_raw(raw: i32) -> Self {
process::ExitStatus::from_raw(raw)
.exit_ok()
.expect_err("<ExitStatusError as ExitStatusExt>::from_raw(0) but zero is not an error")
}
fn signal(&self) -> Option<i32> {
self.into_status().signal()
}
fn core_dumped(&self) -> bool {
self.into_status().core_dumped()
}
fn stopped_signal(&self) -> Option<i32> {
self.into_status().stopped_signal()
}
fn continued(&self) -> bool {
self.into_status().continued()
}
fn into_raw(self) -> i32 {
self.into_status().into_raw()
}
}
#[stable(feature = "process_extensions", since = "1.2.0")]
impl FromRawFd for process::Stdio {
#[inline]
unsafe fn from_raw_fd(fd: RawFd) -> process::Stdio {
let fd = sys::fd::FileDesc::from_raw_fd(fd);
let io = sys::process::Stdio::Fd(fd);
process::Stdio::from_inner(io)
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl From<OwnedFd> for process::Stdio {
#[inline]
fn from(fd: OwnedFd) -> process::Stdio {
let fd = sys::fd::FileDesc::from_inner(fd);
let io = sys::process::Stdio::Fd(fd);
process::Stdio::from_inner(io)
}
}
#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStdin {
#[inline]
fn as_raw_fd(&self) -> RawFd {
self.as_inner().as_raw_fd()
}
}
#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStdout {
#[inline]
fn as_raw_fd(&self) -> RawFd {
self.as_inner().as_raw_fd()
}
}
#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStderr {
#[inline]
fn as_raw_fd(&self) -> RawFd {
self.as_inner().as_raw_fd()
}
}
#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStdin {
#[inline]
fn into_raw_fd(self) -> RawFd {
self.into_inner().into_inner().into_raw_fd()
}
}
#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStdout {
#[inline]
fn into_raw_fd(self) -> RawFd {
self.into_inner().into_inner().into_raw_fd()
}
}
#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStderr {
#[inline]
fn into_raw_fd(self) -> RawFd {
self.into_inner().into_inner().into_raw_fd()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStdin {
#[inline]
fn as_fd(&self) -> BorrowedFd<'_> {
self.as_inner().as_fd()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStdin> for OwnedFd {
#[inline]
fn from(child_stdin: crate::process::ChildStdin) -> OwnedFd {
child_stdin.into_inner().into_inner().into_inner()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStdout {
#[inline]
fn as_fd(&self) -> BorrowedFd<'_> {
self.as_inner().as_fd()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStdout> for OwnedFd {
#[inline]
fn from(child_stdout: crate::process::ChildStdout) -> OwnedFd {
child_stdout.into_inner().into_inner().into_inner()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStderr {
#[inline]
fn as_fd(&self) -> BorrowedFd<'_> {
self.as_inner().as_fd()
}
}
#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStderr> for OwnedFd {
#[inline]
fn from(child_stderr: crate::process::ChildStderr) -> OwnedFd {
child_stderr.into_inner().into_inner().into_inner()
}
}
/// Returns the OS-assigned process identifier associated with this process's parent.
#[must_use]
#[stable(feature = "unix_ppid", since = "1.27.0")]
pub fn parent_id() -> u32 {
crate::sys::os::getppid()
}