1//! The Unix `fcntl` function is effectively lots of different functions hidden
2//! behind a single dynamic dispatch interface. In order to provide a type-safe
3//! API, rustix makes them all separate functions so that they can have
4//! 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 = "vita",
12 target_os = "wasi"
13)))]
14use crate::fs::FlockOperation;
15use crate::{backend, io};
16use backend::fd::AsFd;
17use backend::fs::types::OFlags;
18
19// These `fcntl` functions live in the `io` module because they're not specific
20// to files, directories, or memfd objects. We re-export them here in the `fs`
21// module because the other the `fcntl` functions are here.
22#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
23pub use crate::io::fcntl_dupfd_cloexec;
24pub use crate::io::{fcntl_getfd, fcntl_setfd};
25
26/// `fcntl(fd, F_GETFL)`—Returns a file descriptor's access mode and status.
27///
28/// # References
29/// - [POSIX]
30/// - [Linux]
31///
32/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fcntl.html
33/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
34#[inline]
35#[doc(alias = "F_GETFL")]
36pub fn fcntl_getfl<Fd: AsFd>(fd: Fd) -> io::Result<OFlags> {
37 backend::fs::syscalls::fcntl_getfl(fd.as_fd())
38}
39
40/// `fcntl(fd, F_SETFL, flags)`—Sets a file descriptor's status.
41///
42/// # References
43/// - [POSIX]
44/// - [Linux]
45///
46/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fcntl.html
47/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
48#[inline]
49#[doc(alias = "F_SETFL")]
50pub fn fcntl_setfl<Fd: AsFd>(fd: Fd, flags: OFlags) -> io::Result<()> {
51 backend::fs::syscalls::fcntl_setfl(fd.as_fd(), flags)
52}
53
54/// `fcntl(fd, F_GET_SEALS)`
55///
56/// # References
57/// - [Linux]
58///
59/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
60#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
61#[inline]
62#[doc(alias = "F_GET_SEALS")]
63pub fn fcntl_get_seals<Fd: AsFd>(fd: Fd) -> io::Result<SealFlags> {
64 backend::fs::syscalls::fcntl_get_seals(fd.as_fd())
65}
66
67#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
68use backend::fs::types::SealFlags;
69
70/// `fcntl(fd, F_ADD_SEALS)`
71///
72/// # References
73/// - [Linux]
74///
75/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
76#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
77#[inline]
78#[doc(alias = "F_ADD_SEALS")]
79pub fn fcntl_add_seals<Fd: AsFd>(fd: Fd, seals: SealFlags) -> io::Result<()> {
80 backend::fs::syscalls::fcntl_add_seals(fd.as_fd(), seals)
81}
82
83/// `fcntl(fd, F_SETLK)`—Acquire or release an `fcntl`-style lock.
84///
85/// This function doesn't currently have an offset or len; it currently always
86/// sets the `l_len` field to 0, which is a special case that means the entire
87/// file should be locked.
88///
89/// Unlike `flock`-style locks, `fcntl`-style locks are process-associated,
90/// meaning that they don't guard against being acquired by two threads in the
91/// same process.
92///
93/// # References
94/// - [POSIX]
95/// - [Linux]
96///
97/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fcntl.html
98/// [Linux]: https://man7.org/linux/man-pages/man2/fcntl.2.html
99#[cfg(not(any(
100 target_os = "emscripten",
101 target_os = "espidf",
102 target_os = "fuchsia",
103 target_os = "redox",
104 target_os = "vita",
105 target_os = "wasi"
106)))]
107#[inline]
108#[doc(alias = "F_SETLK")]
109#[doc(alias = "F_SETLKW")]
110pub fn fcntl_lock<Fd: AsFd>(fd: Fd, operation: FlockOperation) -> io::Result<()> {
111 backend::fs::syscalls::fcntl_lock(fd.as_fd(), operation)
112}
113