1//! The Unix `fcntl` function is effectively lots of different functions
2//! hidden behind a single dynamic dispatch interface. In order to provide
3//! a type-safe API, rustix makes them all separate functions so that they
4//! can have dedicated static type signatures.
5
6#[cfg(not(any(
7 target_os = "emscripten",
8 target_os = "espidf",
9 target_os = "fuchsia",
10 target_os = "redox",
11 target_os = "wasi"
12)))]
13use crate::fs::FlockOperation;
14use crate::{backend, io};
15use backend::fd::AsFd;
16use backend::fs::types::OFlags;
17
18// These `fcntl` functions live in the `io` module because they're not specific
19// to files, directories, or memfd objects. We re-export them here in the `fs`
20// module because the other the `fcntl` functions are here.
21#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
22pub use crate::io::fcntl_dupfd_cloexec;
23pub use crate::io::{fcntl_getfd, fcntl_setfd};
24
25/// `fcntl(fd, F_GETFL)`—Returns a file descriptor's access mode and status.
26///
27/// # References
28/// - [POSIX]
29/// - [Linux]
30///
31/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html
32/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
33#[inline]
34#[doc(alias = "F_GETFL")]
35pub fn fcntl_getfl<Fd: AsFd>(fd: Fd) -> io::Result<OFlags> {
36 backend::fs::syscalls::fcntl_getfl(fd.as_fd())
37}
38
39/// `fcntl(fd, F_SETFL, flags)`—Sets a file descriptor's status.
40///
41/// # References
42/// - [POSIX]
43/// - [Linux]
44///
45/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html
46/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
47#[inline]
48#[doc(alias = "F_SETFL")]
49pub fn fcntl_setfl<Fd: AsFd>(fd: Fd, flags: OFlags) -> io::Result<()> {
50 backend::fs::syscalls::fcntl_setfl(fd.as_fd(), flags)
51}
52
53/// `fcntl(fd, F_GET_SEALS)`
54///
55/// # References
56/// - [Linux]
57///
58/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
59#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
60#[inline]
61#[doc(alias = "F_GET_SEALS")]
62pub fn fcntl_get_seals<Fd: AsFd>(fd: Fd) -> io::Result<SealFlags> {
63 backend::fs::syscalls::fcntl_get_seals(fd.as_fd())
64}
65
66#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
67pub use backend::fs::types::SealFlags;
68
69/// `fcntl(fd, F_ADD_SEALS)`
70///
71/// # References
72/// - [Linux]
73///
74/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
75#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
76#[inline]
77#[doc(alias = "F_ADD_SEALS")]
78pub fn fcntl_add_seals<Fd: AsFd>(fd: Fd, seals: SealFlags) -> io::Result<()> {
79 backend::fs::syscalls::fcntl_add_seals(fd.as_fd(), seals)
80}
81
82/// `fcntl(fd, F_SETLK)`—Acquire or release an `fcntl`-style lock.
83///
84/// This function doesn't currently have an offset or len; it currently always
85/// sets the `l_len` field to 0, which is a special case that means the entire
86/// file should be locked.
87///
88/// Unlike `flock`-style locks, `fcntl`-style locks are process-associated,
89/// meaning that they don't guard against being acquired by two threads in
90/// the same process.
91///
92/// # References
93/// - [POSIX]
94/// - [Linux]
95///
96/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html
97/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
98#[cfg(not(any(
99 target_os = "emscripten",
100 target_os = "espidf",
101 target_os = "fuchsia",
102 target_os = "redox",
103 target_os = "wasi"
104)))]
105#[inline]
106#[doc(alias = "F_SETLK")]
107#[doc(alias = "F_SETLKW")]
108pub fn fcntl_lock<Fd: AsFd>(fd: Fd, operation: FlockOperation) -> io::Result<()> {
109 backend::fs::syscalls::fcntl_lock(fd.as_fd(), operation)
110}
111