1 files changed, 403 insertions, 0 deletions
diff --git a/src/backend/libc/termios/syscalls.rs b/src/backend/libc/termios/syscalls.rs
new file mode 100644
index 0000000..a833aea
--- /dev/null
+++ b/src/backend/libc/termios/syscalls.rs
@@ -0,0 +1,403 @@
+//! 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(all(feature = "alloc", 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)]
+    {
+        use crate::termios::{ControlModes, InputModes, LocalModes, OutputModes, SpecialCodes};
+        use crate::utils::default_array;
+
+        let termios2 = unsafe {
+            let mut termios2 = MaybeUninit::<c::termios2>::uninit();
+
+            // QEMU's `TCGETS2` doesn't currently set `input_speed` or
+            // `output_speed` on PowerPC, so zero out the fields ourselves.
+            #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
+            {
+                termios2.write(core::mem::zeroed());
+            }
+
+            ret(c::ioctl(
+                borrowed_fd(fd),
+                c::TCGETS2 as _,
+                termios2.as_mut_ptr(),
+            ))?;
+
+            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(default_array()),
+            input_speed: termios2.c_ispeed,
+            output_speed: termios2.c_ospeed,
+        };
+
+        // QEMU's `TCGETS2` doesn't currently set `input_speed` or
+        // `output_speed` on PowerPC, so set them manually if we can.
+        #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
+        {
+            use crate::termios::speed;
+
+            if result.output_speed == 0 && (termios2.c_cflag & c::CBAUD) != c::BOTHER {
+                if let Some(output_speed) = speed::decode(termios2.c_cflag & c::CBAUD) {
+                    result.output_speed = output_speed;
+                }
+            }
+            if result.input_speed == 0
+                && ((termios2.c_cflag & c::CIBAUD) >> c::IBSHIFT) != c::BOTHER
+            {
+                // For input speeds, `B0` is special-cased to mean the input
+                // speed is the same as the output speed.
+                if ((termios2.c_cflag & c::CIBAUD) >> c::IBSHIFT) == c::B0 {
+                    result.input_speed = result.output_speed;
+                } else if let Some(input_speed) =
+                    speed::decode((termios2.c_cflag & c::CIBAUD) >> c::IBSHIFT)
+                {
+                    result.input_speed = input_speed;
+                }
+            }
+        }
+
+        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)))?;
+
+        // This doesn't appear to be documented, but on Linux, it appears
+        // `tcsetpgrp` can succceed and set the pid to 0 if we pass it a
+        // pseudo-terminal device fd. For now, translate it into `OPNOTSUPP`.
+        #[cfg(linux_kernel)]
+        if pid == 0 {
+            return Err(io::Errno::OPNOTSUPP);
+        }
+
+        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)]
+    {
+        use crate::termios::speed;
+        use crate::utils::default_array;
+        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 = 0x8024_5409;
+        #[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
+        const TCSETS2: u32 = 0x802c_540d;
+
+        // 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: default_array(),
+            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]);
+
+        unsafe { 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 = "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
+    // `BorrowedFd` 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(all(feature = "alloc", 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)),
+        }
+    }
+}