vendor/rustix-0.38.6/src/backend/libc/termios/syscalls.rs - toolchain/rustc - Git at Google

 //! libc syscalls supporting `rustix::termios`.
 //!
 //! # Safety
 //!
 //! See the `rustix::backend::syscalls` module documentation for details.

 use crate::backend::c;
 #[cfg(not(target_os = "wasi"))]
 use crate::backend::conv::ret_pid_t;
 use crate::backend::conv::{borrowed_fd, ret};
 use crate::fd::BorrowedFd;
 #[cfg(feature = "procfs")]
 #[cfg(not(any(target_os = "fuchsia", target_os = "wasi")))]
 use crate::ffi::CStr;
 #[cfg(any(
     not(target_os = "espidf"),
     all(
         feature = "procfs",
         not(any(target_os = "fuchsia", target_os = "wasi"))
     )
 ))]
 use core::mem::MaybeUninit;
 #[cfg(not(target_os = "wasi"))]
 use {crate::io, crate::pid::Pid};
 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 use {
     crate::termios::{Action, OptionalActions, QueueSelector, Termios, Winsize},
     crate::utils::as_mut_ptr,
 };

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcgetattr(fd: BorrowedFd<'_>) -> io::Result<Termios> {
     // If we have `TCGETS2`, use it, so that we fill in the `c_ispeed` and
     // `c_ospeed` fields.
     #[cfg(linux_kernel)]
     unsafe {
         use crate::termios::{ControlModes, InputModes, LocalModes, OutputModes, SpecialCodes};
         use core::mem::zeroed;

         let mut termios2 = MaybeUninit::<c::termios2>::uninit();

         ret(c::ioctl(
             borrowed_fd(fd),
             c::TCGETS2 as _,
             termios2.as_mut_ptr(),
         ))?;

         let termios2 = termios2.assume_init();

         // Convert from the Linux `termios2` to our `Termios`.
         let mut result = Termios {
             input_modes: InputModes::from_bits_retain(termios2.c_iflag),
             output_modes: OutputModes::from_bits_retain(termios2.c_oflag),
             control_modes: ControlModes::from_bits_retain(termios2.c_cflag),
             local_modes: LocalModes::from_bits_retain(termios2.c_lflag),
             line_discipline: termios2.c_line,
             special_codes: SpecialCodes(zeroed()),
             input_speed: termios2.c_ispeed,
             output_speed: termios2.c_ospeed,
         };
         result.special_codes.0[..termios2.c_cc.len()].copy_from_slice(&termios2.c_cc);

         Ok(result)
     }

     #[cfg(not(linux_kernel))]
     unsafe {
         let mut result = MaybeUninit::<Termios>::uninit();

         // `result` is a `Termios` which starts with the same layout as
         // `libc::termios`, so we can cast the pointer.
         ret(c::tcgetattr(borrowed_fd(fd), result.as_mut_ptr().cast()))?;

         Ok(result.assume_init())
     }
 }

 #[cfg(not(target_os = "wasi"))]
 pub(crate) fn tcgetpgrp(fd: BorrowedFd<'_>) -> io::Result<Pid> {
     unsafe {
         let pid = ret_pid_t(c::tcgetpgrp(borrowed_fd(fd)))?;
         Ok(Pid::from_raw_unchecked(pid))
     }
 }

 #[cfg(not(target_os = "wasi"))]
 pub(crate) fn tcsetpgrp(fd: BorrowedFd<'_>, pid: Pid) -> io::Result<()> {
     unsafe { ret(c::tcsetpgrp(borrowed_fd(fd), pid.as_raw_nonzero().get())) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcsetattr(
     fd: BorrowedFd,
     optional_actions: OptionalActions,
     termios: &Termios,
 ) -> io::Result<()> {
     // If we have `TCSETS2`, use it, so that we use the `c_ispeed` and
     // `c_ospeed` fields.
     #[cfg(linux_kernel)]
     unsafe {
         use crate::termios::speed;
         use core::mem::zeroed;
         use linux_raw_sys::general::{termios2, BOTHER, CBAUD, IBSHIFT};

         #[cfg(not(any(target_arch = "sparc", target_arch = "sparc64")))]
         use linux_raw_sys::ioctl::{TCSETS, TCSETS2};

         // linux-raw-sys' ioctl-generation script for sparc isn't working yet,
         // so as a temporary workaround, declare these manually.
         #[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
         const TCSETS: u32 = 0x80245409;
         #[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
         const TCSETS2: u32 = 0x802c540d;

         // Translate from `optional_actions` into an ioctl request code. On MIPS,
         // `optional_actions` already has `TCGETS` added to it.
         let request = TCSETS2
             + if cfg!(any(
                 target_arch = "mips",
                 target_arch = "mips32r6",
                 target_arch = "mips64",
                 target_arch = "mips64r6"
             )) {
                 optional_actions as u32 - TCSETS
             } else {
                 optional_actions as u32
             };

         let input_speed = termios.input_speed();
         let output_speed = termios.output_speed();
         let mut termios2 = termios2 {
             c_iflag: termios.input_modes.bits(),
             c_oflag: termios.output_modes.bits(),
             c_cflag: termios.control_modes.bits(),
             c_lflag: termios.local_modes.bits(),
             c_line: termios.line_discipline,
             c_cc: zeroed(),
             c_ispeed: input_speed,
             c_ospeed: output_speed,
         };
         // Ensure that our input and output speeds are set, as `libc`
         // routines don't always support setting these separately.
         termios2.c_cflag &= !CBAUD;
         termios2.c_cflag |= speed::encode(output_speed).unwrap_or(BOTHER);
         termios2.c_cflag &= !(CBAUD << IBSHIFT);
         termios2.c_cflag |= speed::encode(input_speed).unwrap_or(BOTHER) << IBSHIFT;
         let nccs = termios2.c_cc.len();
         termios2
             .c_cc
             .copy_from_slice(&termios.special_codes.0[..nccs]);

         ret(c::ioctl(borrowed_fd(fd), request as _, &termios2))
     }

     #[cfg(not(linux_kernel))]
     unsafe {
         ret(c::tcsetattr(
             borrowed_fd(fd),
             optional_actions as _,
             crate::utils::as_ptr(termios).cast(),
         ))
     }
 }

 #[cfg(not(target_os = "wasi"))]
 pub(crate) fn tcsendbreak(fd: BorrowedFd) -> io::Result<()> {
     unsafe { ret(c::tcsendbreak(borrowed_fd(fd), 0)) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcdrain(fd: BorrowedFd) -> io::Result<()> {
     unsafe { ret(c::tcdrain(borrowed_fd(fd))) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcflush(fd: BorrowedFd, queue_selector: QueueSelector) -> io::Result<()> {
     unsafe { ret(c::tcflush(borrowed_fd(fd), queue_selector as _)) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcflow(fd: BorrowedFd, action: Action) -> io::Result<()> {
     unsafe { ret(c::tcflow(borrowed_fd(fd), action as _)) }
 }

 #[cfg(not(target_os = "wasi"))]
 pub(crate) fn tcgetsid(fd: BorrowedFd) -> io::Result<Pid> {
     unsafe {
         let pid = ret_pid_t(c::tcgetsid(borrowed_fd(fd)))?;
         Ok(Pid::from_raw_unchecked(pid))
     }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcsetwinsize(fd: BorrowedFd, winsize: Winsize) -> io::Result<()> {
     unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCSWINSZ, &winsize)) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 pub(crate) fn tcgetwinsize(fd: BorrowedFd) -> io::Result<Winsize> {
     unsafe {
         let mut buf = MaybeUninit::<Winsize>::uninit();
         ret(c::ioctl(
             borrowed_fd(fd),
             c::TIOCGWINSZ.into(),
             buf.as_mut_ptr(),
         ))?;
         Ok(buf.assume_init())
     }
 }

 #[cfg(not(any(
     target_os = "espidf",
     target_os = "haiku",
     target_os = "redox",
     target_os = "wasi"
 )))]
 pub(crate) fn ioctl_tiocexcl(fd: BorrowedFd) -> io::Result<()> {
     unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCEXCL as _)) }
 }

 #[cfg(not(any(
     target_os = "espidf",
     target_os = "haiku",
     target_os = "redox",
     target_os = "wasi"
 )))]
 pub(crate) fn ioctl_tiocnxcl(fd: BorrowedFd) -> io::Result<()> {
     unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCNXCL as _)) }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "nto", target_os = "wasi")))]
 #[inline]
 pub(crate) fn set_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
     #[cfg(bsd)]
     let encoded_speed = arbitrary_speed;

     #[cfg(not(bsd))]
     let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
         Some(encoded_speed) => encoded_speed,
         #[cfg(linux_kernel)]
         None => c::BOTHER,
         #[cfg(not(linux_kernel))]
         None => return Err(io::Errno::INVAL),
     };

     #[cfg(not(linux_kernel))]
     unsafe {
         ret(c::cfsetspeed(
             as_mut_ptr(termios).cast(),
             encoded_speed.into(),
         ))
     }

     // Linux libc implementations don't support arbitrary speeds, so we encode
     // the speed manually.
     #[cfg(linux_kernel)]
     {
         use crate::termios::ControlModes;

         debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

         termios.control_modes -= ControlModes::from_bits_retain(c::CBAUD | c::CIBAUD);
         termios.control_modes |=
             ControlModes::from_bits_retain(encoded_speed | (encoded_speed << c::IBSHIFT));

         termios.input_speed = arbitrary_speed;
         termios.output_speed = arbitrary_speed;

         Ok(())
     }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 #[inline]
 pub(crate) fn set_output_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
     #[cfg(bsd)]
     let encoded_speed = arbitrary_speed;

     #[cfg(not(bsd))]
     let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
         Some(encoded_speed) => encoded_speed,
         #[cfg(linux_kernel)]
         None => c::BOTHER,
         #[cfg(not(linux_kernel))]
         None => return Err(io::Errno::INVAL),
     };

     #[cfg(not(linux_kernel))]
     unsafe {
         ret(c::cfsetospeed(
             as_mut_ptr(termios).cast(),
             encoded_speed.into(),
         ))
     }

     // Linux libc implementations don't support arbitrary speeds or setting the
     // input and output speeds separately, so we encode the speed manually.
     #[cfg(linux_kernel)]
     {
         use crate::termios::ControlModes;

         debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

         termios.control_modes -= ControlModes::from_bits_retain(c::CBAUD);
         termios.control_modes |= ControlModes::from_bits_retain(encoded_speed);

         termios.output_speed = arbitrary_speed;

         Ok(())
     }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 #[inline]
 pub(crate) fn set_input_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
     #[cfg(bsd)]
     let encoded_speed = arbitrary_speed;

     #[cfg(not(bsd))]
     let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
         Some(encoded_speed) => encoded_speed,
         #[cfg(linux_kernel)]
         None => c::BOTHER,
         #[cfg(not(linux_kernel))]
         None => return Err(io::Errno::INVAL),
     };

     #[cfg(not(linux_kernel))]
     unsafe {
         ret(c::cfsetispeed(
             as_mut_ptr(termios).cast(),
             encoded_speed.into(),
         ))
     }

     // Linux libc implementations don't support arbitrary speeds or setting the
     // input and output speeds separately, so we encode the speed manually.
     #[cfg(linux_kernel)]
     {
         use crate::termios::ControlModes;

         debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

         termios.control_modes -= ControlModes::from_bits_retain(c::CIBAUD);
         termios.control_modes |= ControlModes::from_bits_retain(encoded_speed << c::IBSHIFT);

         termios.input_speed = arbitrary_speed;

         Ok(())
     }
 }

 #[cfg(not(any(target_os = "espidf", target_os = "nto", target_os = "wasi")))]
 #[inline]
 pub(crate) fn cfmakeraw(termios: &mut Termios) {
     unsafe { c::cfmakeraw(as_mut_ptr(termios).cast()) }
 }

 pub(crate) fn isatty(fd: BorrowedFd<'_>) -> bool {
     // Use the return value of `isatty` alone. We don't check `errno` because
     // we return `bool` rather than `io::Result<bool>`, because we assume
     // `BorrrowedFd` protects us from `EBADF`, and any other reasonably
     // anticipated `errno` value would end up interpreted as “assume it's not a
     // terminal” anyway.
     unsafe { c::isatty(borrowed_fd(fd)) != 0 }
 }

 #[cfg(feature = "procfs")]
 #[cfg(not(any(target_os = "fuchsia", target_os = "wasi")))]
 pub(crate) fn ttyname(dirfd: BorrowedFd<'_>, buf: &mut [MaybeUninit<u8>]) -> io::Result<usize> {
     unsafe {
         // `ttyname_r` returns its error status rather than using `errno`.
         match c::ttyname_r(borrowed_fd(dirfd), buf.as_mut_ptr().cast(), buf.len()) {
             0 => Ok(CStr::from_ptr(buf.as_ptr().cast()).to_bytes().len()),
             err => Err(io::Errno::from_raw_os_error(err)),
         }
     }
 }
	//! libc syscalls supporting `rustix::termios`.
	//!
	//! # Safety
	//!
	//! See the `rustix::backend::syscalls` module documentation for details.

	use crate::backend::c;
	#[cfg(not(target_os = "wasi"))]
	use crate::backend::conv::ret_pid_t;
	use crate::backend::conv::{borrowed_fd, ret};
	use crate::fd::BorrowedFd;
	#[cfg(feature = "procfs")]
	#[cfg(not(any(target_os = "fuchsia", target_os = "wasi")))]
	use crate::ffi::CStr;
	#[cfg(any(
	not(target_os = "espidf"),
	all(
	feature = "procfs",
	not(any(target_os = "fuchsia", target_os = "wasi"))
	)
	))]
	use core::mem::MaybeUninit;
	#[cfg(not(target_os = "wasi"))]
	use {crate::io, crate::pid::Pid};
	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	use {
	crate::termios::{Action, OptionalActions, QueueSelector, Termios, Winsize},
	crate::utils::as_mut_ptr,
	};

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcgetattr(fd: BorrowedFd<'_>) -> io::Result<Termios> {
	// If we have `TCGETS2`, use it, so that we fill in the `c_ispeed` and
	// `c_ospeed` fields.
	#[cfg(linux_kernel)]
	unsafe {
	use crate::termios::{ControlModes, InputModes, LocalModes, OutputModes, SpecialCodes};
	use core::mem::zeroed;

	let mut termios2 = MaybeUninit::<c::termios2>::uninit();

	ret(c::ioctl(
	borrowed_fd(fd),
	c::TCGETS2 as _,
	termios2.as_mut_ptr(),
	))?;

	let termios2 = termios2.assume_init();

	// Convert from the Linux `termios2` to our `Termios`.
	let mut result = Termios {
	input_modes: InputModes::from_bits_retain(termios2.c_iflag),
	output_modes: OutputModes::from_bits_retain(termios2.c_oflag),
	control_modes: ControlModes::from_bits_retain(termios2.c_cflag),
	local_modes: LocalModes::from_bits_retain(termios2.c_lflag),
	line_discipline: termios2.c_line,
	special_codes: SpecialCodes(zeroed()),
	input_speed: termios2.c_ispeed,
	output_speed: termios2.c_ospeed,
	};
	result.special_codes.0[..termios2.c_cc.len()].copy_from_slice(&termios2.c_cc);

	Ok(result)
	}

	#[cfg(not(linux_kernel))]
	unsafe {
	let mut result = MaybeUninit::<Termios>::uninit();

	// `result` is a `Termios` which starts with the same layout as
	// `libc::termios`, so we can cast the pointer.
	ret(c::tcgetattr(borrowed_fd(fd), result.as_mut_ptr().cast()))?;

	Ok(result.assume_init())
	}
	}

	#[cfg(not(target_os = "wasi"))]
	pub(crate) fn tcgetpgrp(fd: BorrowedFd<'_>) -> io::Result<Pid> {
	unsafe {
	let pid = ret_pid_t(c::tcgetpgrp(borrowed_fd(fd)))?;
	Ok(Pid::from_raw_unchecked(pid))
	}
	}

	#[cfg(not(target_os = "wasi"))]
	pub(crate) fn tcsetpgrp(fd: BorrowedFd<'_>, pid: Pid) -> io::Result<()> {
	unsafe { ret(c::tcsetpgrp(borrowed_fd(fd), pid.as_raw_nonzero().get())) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcsetattr(
	fd: BorrowedFd,
	optional_actions: OptionalActions,
	termios: &Termios,
	) -> io::Result<()> {
	// If we have `TCSETS2`, use it, so that we use the `c_ispeed` and
	// `c_ospeed` fields.
	#[cfg(linux_kernel)]
	unsafe {
	use crate::termios::speed;
	use core::mem::zeroed;
	use linux_raw_sys::general::{termios2, BOTHER, CBAUD, IBSHIFT};

	#[cfg(not(any(target_arch = "sparc", target_arch = "sparc64")))]
	use linux_raw_sys::ioctl::{TCSETS, TCSETS2};

	// linux-raw-sys' ioctl-generation script for sparc isn't working yet,
	// so as a temporary workaround, declare these manually.
	#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
	const TCSETS: u32 = 0x80245409;
	#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
	const TCSETS2: u32 = 0x802c540d;

	// Translate from `optional_actions` into an ioctl request code. On MIPS,
	// `optional_actions` already has `TCGETS` added to it.
	let request = TCSETS2
	+ if cfg!(any(
	target_arch = "mips",
	target_arch = "mips32r6",
	target_arch = "mips64",
	target_arch = "mips64r6"
	)) {
	optional_actions as u32 - TCSETS
	} else {
	optional_actions as u32
	};

	let input_speed = termios.input_speed();
	let output_speed = termios.output_speed();
	let mut termios2 = termios2 {
	c_iflag: termios.input_modes.bits(),
	c_oflag: termios.output_modes.bits(),
	c_cflag: termios.control_modes.bits(),
	c_lflag: termios.local_modes.bits(),
	c_line: termios.line_discipline,
	c_cc: zeroed(),
	c_ispeed: input_speed,
	c_ospeed: output_speed,
	};
	// Ensure that our input and output speeds are set, as `libc`
	// routines don't always support setting these separately.
	termios2.c_cflag &= !CBAUD;
	termios2.c_cflag \|= speed::encode(output_speed).unwrap_or(BOTHER);
	termios2.c_cflag &= !(CBAUD << IBSHIFT);
	termios2.c_cflag \|= speed::encode(input_speed).unwrap_or(BOTHER) << IBSHIFT;
	let nccs = termios2.c_cc.len();
	termios2
	.c_cc
	.copy_from_slice(&termios.special_codes.0[..nccs]);

	ret(c::ioctl(borrowed_fd(fd), request as _, &termios2))
	}

	#[cfg(not(linux_kernel))]
	unsafe {
	ret(c::tcsetattr(
	borrowed_fd(fd),
	optional_actions as _,
	crate::utils::as_ptr(termios).cast(),
	))
	}
	}

	#[cfg(not(target_os = "wasi"))]
	pub(crate) fn tcsendbreak(fd: BorrowedFd) -> io::Result<()> {
	unsafe { ret(c::tcsendbreak(borrowed_fd(fd), 0)) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcdrain(fd: BorrowedFd) -> io::Result<()> {
	unsafe { ret(c::tcdrain(borrowed_fd(fd))) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcflush(fd: BorrowedFd, queue_selector: QueueSelector) -> io::Result<()> {
	unsafe { ret(c::tcflush(borrowed_fd(fd), queue_selector as _)) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcflow(fd: BorrowedFd, action: Action) -> io::Result<()> {
	unsafe { ret(c::tcflow(borrowed_fd(fd), action as _)) }
	}

	#[cfg(not(target_os = "wasi"))]
	pub(crate) fn tcgetsid(fd: BorrowedFd) -> io::Result<Pid> {
	unsafe {
	let pid = ret_pid_t(c::tcgetsid(borrowed_fd(fd)))?;
	Ok(Pid::from_raw_unchecked(pid))
	}
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcsetwinsize(fd: BorrowedFd, winsize: Winsize) -> io::Result<()> {
	unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCSWINSZ, &winsize)) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	pub(crate) fn tcgetwinsize(fd: BorrowedFd) -> io::Result<Winsize> {
	unsafe {
	let mut buf = MaybeUninit::<Winsize>::uninit();
	ret(c::ioctl(
	borrowed_fd(fd),
	c::TIOCGWINSZ.into(),
	buf.as_mut_ptr(),
	))?;
	Ok(buf.assume_init())
	}
	}

	#[cfg(not(any(
	target_os = "espidf",
	target_os = "haiku",
	target_os = "redox",
	target_os = "wasi"
	)))]
	pub(crate) fn ioctl_tiocexcl(fd: BorrowedFd) -> io::Result<()> {
	unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCEXCL as _)) }
	}

	#[cfg(not(any(
	target_os = "espidf",
	target_os = "haiku",
	target_os = "redox",
	target_os = "wasi"
	)))]
	pub(crate) fn ioctl_tiocnxcl(fd: BorrowedFd) -> io::Result<()> {
	unsafe { ret(c::ioctl(borrowed_fd(fd), c::TIOCNXCL as _)) }
	}

	#[cfg(not(any(target_os = "espidf", target_os = "nto", target_os = "wasi")))]
	#[inline]
	pub(crate) fn set_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
	#[cfg(bsd)]
	let encoded_speed = arbitrary_speed;

	#[cfg(not(bsd))]
	let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
	Some(encoded_speed) => encoded_speed,
	#[cfg(linux_kernel)]
	None => c::BOTHER,
	#[cfg(not(linux_kernel))]
	None => return Err(io::Errno::INVAL),
	};

	#[cfg(not(linux_kernel))]
	unsafe {
	ret(c::cfsetspeed(
	as_mut_ptr(termios).cast(),
	encoded_speed.into(),
	))
	}

	// Linux libc implementations don't support arbitrary speeds, so we encode
	// the speed manually.
	#[cfg(linux_kernel)]
	{
	use crate::termios::ControlModes;

	debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

	termios.control_modes -= ControlModes::from_bits_retain(c::CBAUD \| c::CIBAUD);
	termios.control_modes \|=
	ControlModes::from_bits_retain(encoded_speed \| (encoded_speed << c::IBSHIFT));

	termios.input_speed = arbitrary_speed;
	termios.output_speed = arbitrary_speed;

	Ok(())
	}
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	#[inline]
	pub(crate) fn set_output_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
	#[cfg(bsd)]
	let encoded_speed = arbitrary_speed;

	#[cfg(not(bsd))]
	let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
	Some(encoded_speed) => encoded_speed,
	#[cfg(linux_kernel)]
	None => c::BOTHER,
	#[cfg(not(linux_kernel))]
	None => return Err(io::Errno::INVAL),
	};

	#[cfg(not(linux_kernel))]
	unsafe {
	ret(c::cfsetospeed(
	as_mut_ptr(termios).cast(),
	encoded_speed.into(),
	))
	}

	// Linux libc implementations don't support arbitrary speeds or setting the
	// input and output speeds separately, so we encode the speed manually.
	#[cfg(linux_kernel)]
	{
	use crate::termios::ControlModes;

	debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

	termios.control_modes -= ControlModes::from_bits_retain(c::CBAUD);
	termios.control_modes \|= ControlModes::from_bits_retain(encoded_speed);

	termios.output_speed = arbitrary_speed;

	Ok(())
	}
	}

	#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
	#[inline]
	pub(crate) fn set_input_speed(termios: &mut Termios, arbitrary_speed: u32) -> io::Result<()> {
	#[cfg(bsd)]
	let encoded_speed = arbitrary_speed;

	#[cfg(not(bsd))]
	let encoded_speed = match crate::termios::speed::encode(arbitrary_speed) {
	Some(encoded_speed) => encoded_speed,
	#[cfg(linux_kernel)]
	None => c::BOTHER,
	#[cfg(not(linux_kernel))]
	None => return Err(io::Errno::INVAL),
	};

	#[cfg(not(linux_kernel))]
	unsafe {
	ret(c::cfsetispeed(
	as_mut_ptr(termios).cast(),
	encoded_speed.into(),
	))
	}

	// Linux libc implementations don't support arbitrary speeds or setting the
	// input and output speeds separately, so we encode the speed manually.
	#[cfg(linux_kernel)]
	{
	use crate::termios::ControlModes;

	debug_assert_eq!(encoded_speed & !c::CBAUD, 0);

	termios.control_modes -= ControlModes::from_bits_retain(c::CIBAUD);
	termios.control_modes \|= ControlModes::from_bits_retain(encoded_speed << c::IBSHIFT);

	termios.input_speed = arbitrary_speed;

	Ok(())
	}
	}

	#[cfg(not(any(target_os = "espidf", target_os = "nto", target_os = "wasi")))]
	#[inline]
	pub(crate) fn cfmakeraw(termios: &mut Termios) {
	unsafe { c::cfmakeraw(as_mut_ptr(termios).cast()) }
	}

	pub(crate) fn isatty(fd: BorrowedFd<'_>) -> bool {
	// Use the return value of `isatty` alone. We don't check `errno` because
	// we return `bool` rather than `io::Result<bool>`, because we assume
	// `BorrrowedFd` protects us from `EBADF`, and any other reasonably
	// anticipated `errno` value would end up interpreted as “assume it's not a
	// terminal” anyway.
	unsafe { c::isatty(borrowed_fd(fd)) != 0 }
	}

	#[cfg(feature = "procfs")]
	#[cfg(not(any(target_os = "fuchsia", target_os = "wasi")))]
	pub(crate) fn ttyname(dirfd: BorrowedFd<'_>, buf: &mut [MaybeUninit<u8>]) -> io::Result<usize> {
	unsafe {
	// `ttyname_r` returns its error status rather than using `errno`.
	match c::ttyname_r(borrowed_fd(dirfd), buf.as_mut_ptr().cast(), buf.len()) {
	0 => Ok(CStr::from_ptr(buf.as_ptr().cast()).to_bytes().len()),
	err => Err(io::Errno::from_raw_os_error(err)),
	}
	}
	}