1 //! The `madvise` function.
2 //!
3 //! # Safety
4 //!
5 //! `madvise` operates on a raw pointer. Some forms of `madvise` may
6 //! mutate the memory or have other side effects.
7 #![allow(unsafe_code)]
8 
9 use crate::{backend, io};
10 use core::ffi::c_void;
11 
12 pub use backend::mm::types::Advice;
13 
14 /// `posix_madvise(addr, len, advice)`—Declares an expected access pattern
15 /// for a memory-mapped file.
16 ///
17 /// # Safety
18 ///
19 /// `addr` must be a valid pointer to memory that is appropriate to call
20 /// `posix_madvise` on. Some forms of `advice` may mutate the memory or evoke a
21 /// variety of side-effects on the mapping and/or the file.
22 ///
23 /// # References
24 ///  - [POSIX]
25 ///  - [Linux `madvise`]
26 ///  - [Linux `posix_madvise`]
27 ///  - [Apple]
28 ///  - [FreeBSD]
29 ///  - [NetBSD]
30 ///  - [OpenBSD]
31 ///  - [DragonFly BSD]
32 ///  - [illumos]
33 ///  - [glibc]
34 ///
35 /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_madvise.html
36 /// [Linux `madvise`]: https://man7.org/linux/man-pages/man2/madvise.2.html
37 /// [Linux `posix_madvise`]: https://man7.org/linux/man-pages/man3/posix_madvise.3.html
38 /// [Apple]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/madvise.2.html
39 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=madvise&sektion=2
40 /// [NetBSD]: https://man.netbsd.org/madvise.2
41 /// [OpenBSD]: https://man.openbsd.org/madvise.2
42 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=madvise&section=2
43 /// [illumos]: https://illumos.org/man/3C/madvise
44 /// [glibc]: https://www.gnu.org/software/libc/manual/html_node/Memory_002dmapped-I_002fO.html#index-madvise
45 #[inline]
46 #[doc(alias = "posix_madvise")]
madvise(addr: *mut c_void, len: usize, advice: Advice) -> io::Result<()>47 pub unsafe fn madvise(addr: *mut c_void, len: usize, advice: Advice) -> io::Result<()> {
48     backend::mm::syscalls::madvise(addr, len, advice)
49 }
50