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Diffstat (limited to 'third_party/rust/nix/src/pty.rs')
| -rw-r--r-- | third_party/rust/nix/src/pty.rs | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/third_party/rust/nix/src/pty.rs b/third_party/rust/nix/src/pty.rs new file mode 100644 index 0000000000..28ae5e924b --- /dev/null +++ b/third_party/rust/nix/src/pty.rs @@ -0,0 +1,371 @@ +//! Create master and slave virtual pseudo-terminals (PTYs) + +pub use libc::pid_t as SessionId; +pub use libc::winsize as Winsize; + +use std::ffi::CStr; +use std::io; +use std::mem; +use std::os::unix::prelude::*; + +use crate::errno::Errno; +use crate::sys::termios::Termios; +#[cfg(feature = "process")] +use crate::unistd::{ForkResult, Pid}; +use crate::{fcntl, unistd, Result}; + +/// Representation of a master/slave pty pair +/// +/// This is returned by `openpty`. Note that this type does *not* implement `Drop`, so the user +/// must manually close the file descriptors. +#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)] +pub struct OpenptyResult { + /// The master port in a virtual pty pair + pub master: RawFd, + /// The slave port in a virtual pty pair + pub slave: RawFd, +} + +feature! { +#![feature = "process"] +/// Representation of a master with a forked pty +/// +/// This is returned by `forkpty`. Note that this type does *not* implement `Drop`, so the user +/// must manually close the file descriptors. +#[derive(Clone, Copy, Debug)] +pub struct ForkptyResult { + /// The master port in a virtual pty pair + pub master: RawFd, + /// Metadata about forked process + pub fork_result: ForkResult, +} +} + +/// Representation of the Master device in a master/slave pty pair +/// +/// While this datatype is a thin wrapper around `RawFd`, it enforces that the available PTY +/// functions are given the correct file descriptor. Additionally this type implements `Drop`, +/// so that when it's consumed or goes out of scope, it's automatically cleaned-up. +#[derive(Debug, Eq, Hash, PartialEq)] +pub struct PtyMaster(RawFd); + +impl AsRawFd for PtyMaster { + fn as_raw_fd(&self) -> RawFd { + self.0 + } +} + +impl IntoRawFd for PtyMaster { + fn into_raw_fd(self) -> RawFd { + let fd = self.0; + mem::forget(self); + fd + } +} + +impl Drop for PtyMaster { + fn drop(&mut self) { + // On drop, we ignore errors like EINTR and EIO because there's no clear + // way to handle them, we can't return anything, and (on FreeBSD at + // least) the file descriptor is deallocated in these cases. However, + // we must panic on EBADF, because it is always an error to close an + // invalid file descriptor. That frequently indicates a double-close + // condition, which can cause confusing errors for future I/O + // operations. + let e = unistd::close(self.0); + if e == Err(Errno::EBADF) { + panic!("Closing an invalid file descriptor!"); + }; + } +} + +impl io::Read for PtyMaster { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + unistd::read(self.0, buf).map_err(io::Error::from) + } +} + +impl io::Write for PtyMaster { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + unistd::write(self.0, buf).map_err(io::Error::from) + } + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } +} + +impl io::Read for &PtyMaster { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + unistd::read(self.0, buf).map_err(io::Error::from) + } +} + +impl io::Write for &PtyMaster { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + unistd::write(self.0, buf).map_err(io::Error::from) + } + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } +} + +/// Grant access to a slave pseudoterminal (see +/// [`grantpt(3)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/grantpt.html)) +/// +/// `grantpt()` changes the mode and owner of the slave pseudoterminal device corresponding to the +/// master pseudoterminal referred to by `fd`. This is a necessary step towards opening the slave. +#[inline] +pub fn grantpt(fd: &PtyMaster) -> Result<()> { + if unsafe { libc::grantpt(fd.as_raw_fd()) } < 0 { + return Err(Errno::last()); + } + + Ok(()) +} + +/// Open a pseudoterminal device (see +/// [`posix_openpt(3)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_openpt.html)) +/// +/// `posix_openpt()` returns a file descriptor to an existing unused pseudoterminal master device. +/// +/// # Examples +/// +/// A common use case with this function is to open both a master and slave PTY pair. This can be +/// done as follows: +/// +/// ``` +/// use std::path::Path; +/// use nix::fcntl::{OFlag, open}; +/// use nix::pty::{grantpt, posix_openpt, ptsname, unlockpt}; +/// use nix::sys::stat::Mode; +/// +/// # #[allow(dead_code)] +/// # fn run() -> nix::Result<()> { +/// // Open a new PTY master +/// let master_fd = posix_openpt(OFlag::O_RDWR)?; +/// +/// // Allow a slave to be generated for it +/// grantpt(&master_fd)?; +/// unlockpt(&master_fd)?; +/// +/// // Get the name of the slave +/// let slave_name = unsafe { ptsname(&master_fd) }?; +/// +/// // Try to open the slave +/// let _slave_fd = open(Path::new(&slave_name), OFlag::O_RDWR, Mode::empty())?; +/// # Ok(()) +/// # } +/// ``` +#[inline] +pub fn posix_openpt(flags: fcntl::OFlag) -> Result<PtyMaster> { + let fd = unsafe { libc::posix_openpt(flags.bits()) }; + + if fd < 0 { + return Err(Errno::last()); + } + + Ok(PtyMaster(fd)) +} + +/// Get the name of the slave pseudoterminal (see +/// [`ptsname(3)`](https://man7.org/linux/man-pages/man3/ptsname.3.html)) +/// +/// `ptsname()` returns the name of the slave pseudoterminal device corresponding to the master +/// referred to by `fd`. +/// +/// This value is useful for opening the slave pty once the master has already been opened with +/// `posix_openpt()`. +/// +/// # Safety +/// +/// `ptsname()` mutates global variables and is *not* threadsafe. +/// Mutating global variables is always considered `unsafe` by Rust and this +/// function is marked as `unsafe` to reflect that. +/// +/// For a threadsafe and non-`unsafe` alternative on Linux, see `ptsname_r()`. +#[inline] +pub unsafe fn ptsname(fd: &PtyMaster) -> Result<String> { + let name_ptr = libc::ptsname(fd.as_raw_fd()); + if name_ptr.is_null() { + return Err(Errno::last()); + } + + let name = CStr::from_ptr(name_ptr); + Ok(name.to_string_lossy().into_owned()) +} + +/// Get the name of the slave pseudoterminal (see +/// [`ptsname(3)`](https://man7.org/linux/man-pages/man3/ptsname.3.html)) +/// +/// `ptsname_r()` returns the name of the slave pseudoterminal device corresponding to the master +/// referred to by `fd`. This is the threadsafe version of `ptsname()`, but it is not part of the +/// POSIX standard and is instead a Linux-specific extension. +/// +/// This value is useful for opening the slave ptty once the master has already been opened with +/// `posix_openpt()`. +#[cfg(any(target_os = "android", target_os = "linux"))] +#[cfg_attr(docsrs, doc(cfg(all())))] +#[inline] +pub fn ptsname_r(fd: &PtyMaster) -> Result<String> { + let mut name_buf = Vec::<libc::c_char>::with_capacity(64); + let name_buf_ptr = name_buf.as_mut_ptr(); + let cname = unsafe { + let cap = name_buf.capacity(); + if libc::ptsname_r(fd.as_raw_fd(), name_buf_ptr, cap) != 0 { + return Err(crate::Error::last()); + } + CStr::from_ptr(name_buf.as_ptr()) + }; + + let name = cname.to_string_lossy().into_owned(); + Ok(name) +} + +/// Unlock a pseudoterminal master/slave pseudoterminal pair (see +/// [`unlockpt(3)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/unlockpt.html)) +/// +/// `unlockpt()` unlocks the slave pseudoterminal device corresponding to the master pseudoterminal +/// referred to by `fd`. This must be called before trying to open the slave side of a +/// pseudoterminal. +#[inline] +pub fn unlockpt(fd: &PtyMaster) -> Result<()> { + if unsafe { libc::unlockpt(fd.as_raw_fd()) } < 0 { + return Err(Errno::last()); + } + + Ok(()) +} + +/// Create a new pseudoterminal, returning the slave and master file descriptors +/// in `OpenptyResult` +/// (see [`openpty`](https://man7.org/linux/man-pages/man3/openpty.3.html)). +/// +/// If `winsize` is not `None`, the window size of the slave will be set to +/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's +/// terminal settings of the slave will be set to the values in `termios`. +#[inline] +pub fn openpty< + 'a, + 'b, + T: Into<Option<&'a Winsize>>, + U: Into<Option<&'b Termios>>, +>( + winsize: T, + termios: U, +) -> Result<OpenptyResult> { + use std::ptr; + + let mut slave = mem::MaybeUninit::<libc::c_int>::uninit(); + let mut master = mem::MaybeUninit::<libc::c_int>::uninit(); + let ret = { + match (termios.into(), winsize.into()) { + (Some(termios), Some(winsize)) => { + let inner_termios = termios.get_libc_termios(); + unsafe { + libc::openpty( + master.as_mut_ptr(), + slave.as_mut_ptr(), + ptr::null_mut(), + &*inner_termios as *const libc::termios as *mut _, + winsize as *const Winsize as *mut _, + ) + } + } + (None, Some(winsize)) => unsafe { + libc::openpty( + master.as_mut_ptr(), + slave.as_mut_ptr(), + ptr::null_mut(), + ptr::null_mut(), + winsize as *const Winsize as *mut _, + ) + }, + (Some(termios), None) => { + let inner_termios = termios.get_libc_termios(); + unsafe { + libc::openpty( + master.as_mut_ptr(), + slave.as_mut_ptr(), + ptr::null_mut(), + &*inner_termios as *const libc::termios as *mut _, + ptr::null_mut(), + ) + } + } + (None, None) => unsafe { + libc::openpty( + master.as_mut_ptr(), + slave.as_mut_ptr(), + ptr::null_mut(), + ptr::null_mut(), + ptr::null_mut(), + ) + }, + } + }; + + Errno::result(ret)?; + + unsafe { + Ok(OpenptyResult { + master: master.assume_init(), + slave: slave.assume_init(), + }) + } +} + +feature! { +#![feature = "process"] +/// Create a new pseudoterminal, returning the master file descriptor and forked pid. +/// in `ForkptyResult` +/// (see [`forkpty`](https://man7.org/linux/man-pages/man3/forkpty.3.html)). +/// +/// If `winsize` is not `None`, the window size of the slave will be set to +/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's +/// terminal settings of the slave will be set to the values in `termios`. +/// +/// # Safety +/// +/// In a multithreaded program, only [async-signal-safe] functions like `pause` +/// and `_exit` may be called by the child (the parent isn't restricted). Note +/// that memory allocation may **not** be async-signal-safe and thus must be +/// prevented. +/// +/// Those functions are only a small subset of your operating system's API, so +/// special care must be taken to only invoke code you can control and audit. +/// +/// [async-signal-safe]: https://man7.org/linux/man-pages/man7/signal-safety.7.html +pub unsafe fn forkpty<'a, 'b, T: Into<Option<&'a Winsize>>, U: Into<Option<&'b Termios>>>( + winsize: T, + termios: U, +) -> Result<ForkptyResult> { + use std::ptr; + + let mut master = mem::MaybeUninit::<libc::c_int>::uninit(); + + let term = match termios.into() { + Some(termios) => { + let inner_termios = termios.get_libc_termios(); + &*inner_termios as *const libc::termios as *mut _ + }, + None => ptr::null_mut(), + }; + + let win = winsize + .into() + .map(|ws| ws as *const Winsize as *mut _) + .unwrap_or(ptr::null_mut()); + + let res = libc::forkpty(master.as_mut_ptr(), ptr::null_mut(), term, win); + + let fork_result = Errno::result(res).map(|res| match res { + 0 => ForkResult::Child, + res => ForkResult::Parent { child: Pid::from_raw(res) }, + })?; + + Ok(ForkptyResult { + master: master.assume_init(), + fork_result, + }) +} +} |