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//! libc syscalls supporting `rustix::pty`.
use crate::backend::c;
use crate::backend::conv::{borrowed_fd, ret};
use crate::fd::BorrowedFd;
use crate::io;
#[cfg(all(
feature = "alloc",
any(apple, linux_like, target_os = "freebsd", target_os = "fuchsia")
))]
use {
crate::ffi::{CStr, CString},
crate::path::SMALL_PATH_BUFFER_SIZE,
alloc::borrow::ToOwned,
alloc::vec::Vec,
};
#[cfg(not(linux_kernel))]
use crate::{backend::conv::ret_owned_fd, fd::OwnedFd, pty::OpenptFlags};
#[cfg(not(linux_kernel))]
#[inline]
pub(crate) fn openpt(flags: OpenptFlags) -> io::Result<OwnedFd> {
unsafe { ret_owned_fd(c::posix_openpt(flags.bits() as _)) }
}
#[cfg(all(
feature = "alloc",
any(apple, linux_like, target_os = "freebsd", target_os = "fuchsia")
))]
#[inline]
pub(crate) fn ptsname(fd: BorrowedFd<'_>, mut buffer: Vec<u8>) -> io::Result<CString> {
// This code would benefit from having a better way to read into
// uninitialized memory, but that requires `unsafe`.
buffer.clear();
buffer.reserve(SMALL_PATH_BUFFER_SIZE);
buffer.resize(buffer.capacity(), 0_u8);
loop {
// On platforms with `ptsname_r`, use it.
#[cfg(any(linux_like, target_os = "fuchsia"))]
let r = unsafe { c::ptsname_r(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len()) };
// FreeBSD 12 doesn't have `ptsname_r`.
#[cfg(target_os = "freebsd")]
let r = unsafe {
weak! {
fn ptsname_r(
c::c_int,
*mut c::c_char,
c::size_t
) -> c::c_int
}
if let Some(func) = ptsname_r.get() {
func(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len())
} else {
libc::ENOSYS
}
};
// macOS 10.13.4 has `ptsname_r`; use it if we have it, otherwise fall
// back to calling the underlying ioctl directly.
#[cfg(apple)]
let r = unsafe {
weak! { fn ptsname_r(c::c_int, *mut c::c_char, c::size_t) -> c::c_int }
if let Some(libc_ptsname_r) = ptsname_r.get() {
libc_ptsname_r(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len())
} else {
// The size declared in the `TIOCPTYGNAME` macro in
// sys/ttycom.h is 128.
let mut name: [u8; 128] = [0_u8; 128];
match c::ioctl(borrowed_fd(fd), c::TIOCPTYGNAME as _, &mut name) {
0 => {
let len = CStr::from_ptr(name.as_ptr().cast()).to_bytes().len();
std::ptr::copy_nonoverlapping(name.as_ptr(), buffer.as_mut_ptr(), len + 1);
0
}
_ => libc_errno::errno().0,
}
}
};
if r == 0 {
return Ok(unsafe { CStr::from_ptr(buffer.as_ptr().cast()).to_owned() });
}
if r != c::ERANGE {
return Err(io::Errno::from_raw_os_error(r));
}
// Use `Vec` reallocation strategy to grow capacity exponentially.
buffer.reserve(1);
buffer.resize(buffer.capacity(), 0_u8);
}
}
#[inline]
pub(crate) fn unlockpt(fd: BorrowedFd<'_>) -> io::Result<()> {
unsafe { ret(c::unlockpt(borrowed_fd(fd))) }
}
#[cfg(not(linux_kernel))]
#[inline]
pub(crate) fn grantpt(fd: BorrowedFd<'_>) -> io::Result<()> {
unsafe { ret(c::grantpt(borrowed_fd(fd))) }
}