1 //! libc syscalls supporting `rustix::pty`.
2
3 use crate::backend::c;
4 use crate::backend::conv::{borrowed_fd, ret};
5 use crate::fd::BorrowedFd;
6 use crate::io;
7 #[cfg(all(
8 feature = "alloc",
9 any(apple, linux_like, target_os = "freebsd", target_os = "fuchsia")
10 ))]
11 use {
12 crate::ffi::{CStr, CString},
13 crate::path::SMALL_PATH_BUFFER_SIZE,
14 alloc::borrow::ToOwned,
15 alloc::vec::Vec,
16 };
17
18 #[cfg(not(linux_kernel))]
19 use crate::{backend::conv::ret_owned_fd, fd::OwnedFd, pty::OpenptFlags};
20
21 use errno as libc_errno;
22
23 #[cfg(not(linux_kernel))]
24 #[inline]
openpt(flags: OpenptFlags) -> io::Result<OwnedFd>25 pub(crate) fn openpt(flags: OpenptFlags) -> io::Result<OwnedFd> {
26 unsafe { ret_owned_fd(c::posix_openpt(flags.bits() as _)) }
27 }
28
29 #[cfg(all(
30 feature = "alloc",
31 any(apple, linux_like, target_os = "freebsd", target_os = "fuchsia")
32 ))]
33 #[inline]
ptsname(fd: BorrowedFd<'_>, mut buffer: Vec<u8>) -> io::Result<CString>34 pub(crate) fn ptsname(fd: BorrowedFd<'_>, mut buffer: Vec<u8>) -> io::Result<CString> {
35 // This code would benefit from having a better way to read into
36 // uninitialized memory, but that requires `unsafe`.
37 buffer.clear();
38 buffer.reserve(SMALL_PATH_BUFFER_SIZE);
39 buffer.resize(buffer.capacity(), 0_u8);
40
41 loop {
42 // On platforms with `ptsname_r`, use it.
43 #[cfg(any(linux_like, target_os = "fuchsia"))]
44 let r = unsafe { c::ptsname_r(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len()) };
45
46 // FreeBSD 12 doesn't have `ptsname_r`.
47 #[cfg(target_os = "freebsd")]
48 let r = unsafe {
49 weak! {
50 fn ptsname_r(
51 c::c_int,
52 *mut c::c_char,
53 c::size_t
54 ) -> c::c_int
55 }
56 if let Some(func) = ptsname_r.get() {
57 func(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len())
58 } else {
59 libc::ENOSYS
60 }
61 };
62
63 // macOS 10.13.4 has `ptsname_r`; use it if we have it, otherwise fall
64 // back to calling the underlying ioctl directly.
65 #[cfg(apple)]
66 let r = unsafe {
67 weak! { fn ptsname_r(c::c_int, *mut c::c_char, c::size_t) -> c::c_int }
68
69 if let Some(libc_ptsname_r) = ptsname_r.get() {
70 libc_ptsname_r(borrowed_fd(fd), buffer.as_mut_ptr().cast(), buffer.len())
71 } else {
72 // The size declared in the `TIOCPTYGNAME` macro in
73 // sys/ttycom.h is 128.
74 let mut name: [u8; 128] = [0_u8; 128];
75 match c::ioctl(borrowed_fd(fd), c::TIOCPTYGNAME as _, &mut name) {
76 0 => {
77 let len = CStr::from_ptr(name.as_ptr().cast()).to_bytes().len();
78 std::ptr::copy_nonoverlapping(name.as_ptr(), buffer.as_mut_ptr(), len + 1);
79 0
80 }
81 _ => libc_errno::errno().0,
82 }
83 }
84 };
85
86 if r == 0 {
87 return Ok(unsafe { CStr::from_ptr(buffer.as_ptr().cast()).to_owned() });
88 }
89 if r != c::ERANGE {
90 return Err(io::Errno::from_raw_os_error(r));
91 }
92
93 // Use `Vec` reallocation strategy to grow capacity exponentially.
94 buffer.reserve(1);
95 buffer.resize(buffer.capacity(), 0_u8);
96 }
97 }
98
99 #[inline]
unlockpt(fd: BorrowedFd<'_>) -> io::Result<()>100 pub(crate) fn unlockpt(fd: BorrowedFd<'_>) -> io::Result<()> {
101 unsafe { ret(c::unlockpt(borrowed_fd(fd))) }
102 }
103
104 #[cfg(not(linux_kernel))]
105 #[inline]
grantpt(fd: BorrowedFd<'_>) -> io::Result<()>106 pub(crate) fn grantpt(fd: BorrowedFd<'_>) -> io::Result<()> {
107 unsafe { ret(c::grantpt(borrowed_fd(fd))) }
108 }
109