1 | //! Functions which operate on file descriptors which might be terminals. |
2 | |
3 | use crate::backend; |
4 | use backend::fd::AsFd; |
5 | #[cfg (all(feature = "alloc" , feature = "procfs" ))] |
6 | #[cfg (not(any(target_os = "fuchsia" , target_os = "wasi" )))] |
7 | use { |
8 | crate::ffi::CString, crate::io, crate::path::SMALL_PATH_BUFFER_SIZE, alloc::vec::Vec, |
9 | backend::fd::BorrowedFd, |
10 | }; |
11 | |
12 | /// `isatty(fd)`—Tests whether a file descriptor refers to a terminal. |
13 | /// |
14 | /// # References |
15 | /// - [POSIX] |
16 | /// - [Linux] |
17 | /// |
18 | /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/isatty.html |
19 | /// [Linux]: https://man7.org/linux/man-pages/man3/isatty.3.html |
20 | #[inline ] |
21 | pub fn isatty<Fd: AsFd>(fd: Fd) -> bool { |
22 | backend::termios::syscalls::isatty(fd.as_fd()) |
23 | } |
24 | |
25 | /// `ttyname_r(fd)` |
26 | /// |
27 | /// If `reuse` already has available capacity, reuse it if possible. |
28 | /// |
29 | /// # References |
30 | /// - [POSIX] |
31 | /// - [Linux] |
32 | /// |
33 | /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/ttyname.html |
34 | /// [Linux]: https://man7.org/linux/man-pages/man3/ttyname.3.html |
35 | #[cfg (not(any(target_os = "fuchsia" , target_os = "wasi" )))] |
36 | #[cfg (all(feature = "alloc" , feature = "procfs" ))] |
37 | #[cfg_attr (doc_cfg, doc(cfg(feature = "procfs" )))] |
38 | #[doc (alias = "ttyname_r" )] |
39 | #[inline ] |
40 | pub fn ttyname<Fd: AsFd, B: Into<Vec<u8>>>(dirfd: Fd, reuse: B) -> io::Result<CString> { |
41 | _ttyname(dirfd.as_fd(), reuse.into()) |
42 | } |
43 | |
44 | #[cfg (not(any(target_os = "fuchsia" , target_os = "wasi" )))] |
45 | #[cfg (all(feature = "alloc" , feature = "procfs" ))] |
46 | #[allow (unsafe_code)] |
47 | fn _ttyname(dirfd: BorrowedFd<'_>, mut buffer: Vec<u8>) -> io::Result<CString> { |
48 | buffer.clear(); |
49 | buffer.reserve(SMALL_PATH_BUFFER_SIZE); |
50 | |
51 | loop { |
52 | match backend::termios::syscalls::ttyname(dirfd, buffer.spare_capacity_mut()) { |
53 | Err(io::Errno::RANGE) => { |
54 | // Use `Vec` reallocation strategy to grow capacity |
55 | // exponentially. |
56 | buffer.reserve(buffer.capacity() + 1); |
57 | } |
58 | Ok(len) => { |
59 | // SAFETY: Assume the backend returns the length of the string |
60 | // excluding the NUL. |
61 | unsafe { |
62 | buffer.set_len(len + 1); |
63 | } |
64 | |
65 | // SAFETY: |
66 | // - "ttyname_r stores this pathname in the buffer buf" |
67 | // - [POSIX definition 3.271: Pathname]: "A string that is used to identify a |
68 | // file." |
69 | // - [POSIX definition 3.375: String]: "A contiguous sequence of bytes |
70 | // terminated by and including the first null byte." |
71 | // |
72 | // Thus, there will be a single NUL byte at the end of the |
73 | // string. |
74 | // |
75 | // [POSIX definition 3.271: Pathname]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_271 |
76 | // [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_375 |
77 | unsafe { |
78 | return Ok(CString::from_vec_with_nul_unchecked(buffer)); |
79 | } |
80 | } |
81 | Err(errno) => return Err(errno), |
82 | } |
83 | } |
84 | } |
85 | |