nix/sys/resource.rs
1//! Configure the process resource limits.
2use cfg_if::cfg_if;
3
4use crate::errno::Errno;
5use crate::Result;
6pub use libc::rlim_t;
7use std::mem;
8
9cfg_if! {
10 if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
11 use libc::{__rlimit_resource_t, rlimit, RLIM_INFINITY};
12 }else if #[cfg(any(
13 target_os = "freebsd",
14 target_os = "openbsd",
15 target_os = "netbsd",
16 target_os = "macos",
17 target_os = "ios",
18 target_os = "android",
19 target_os = "dragonfly",
20 all(target_os = "linux", not(target_env = "gnu"))
21 ))]{
22 use libc::{c_int, rlimit, RLIM_INFINITY};
23 }
24}
25
26libc_enum! {
27 /// The Resource enum is platform dependent. Check different platform
28 /// manuals for more details. Some platform links has been provided for
29 /// earier reference (non-exhaustive).
30 ///
31 /// * [Linux](https://man7.org/linux/man-pages/man2/getrlimit.2.html)
32 /// * [FreeBSD](https://www.freebsd.org/cgi/man.cgi?query=setrlimit)
33
34 // linux-gnu uses u_int as resource enum, which is implemented in libc as
35 // well.
36 //
37 // https://gcc.gnu.org/legacy-ml/gcc/2015-08/msg00441.html
38 // https://github.com/rust-lang/libc/blob/master/src/unix/linux_like/linux/gnu/mod.rs
39 #[cfg_attr(all(target_os = "linux", target_env = "gnu"), repr(u32))]
40 #[cfg_attr(any(
41 target_os = "freebsd",
42 target_os = "openbsd",
43 target_os = "netbsd",
44 target_os = "macos",
45 target_os = "ios",
46 target_os = "android",
47 target_os = "dragonfly",
48 all(target_os = "linux", not(target_env = "gnu"))
49 ), repr(i32))]
50 #[non_exhaustive]
51 pub enum Resource {
52 #[cfg(not(any(
53 target_os = "freebsd",
54 target_os = "netbsd",
55 target_os = "openbsd"
56 )))]
57 /// The maximum amount (in bytes) of virtual memory the process is
58 /// allowed to map.
59 RLIMIT_AS,
60 /// The largest size (in bytes) core(5) file that may be created.
61 RLIMIT_CORE,
62 /// The maximum amount of cpu time (in seconds) to be used by each
63 /// process.
64 RLIMIT_CPU,
65 /// The maximum size (in bytes) of the data segment for a process
66 RLIMIT_DATA,
67 /// The largest size (in bytes) file that may be created.
68 RLIMIT_FSIZE,
69 /// The maximum number of open files for this process.
70 RLIMIT_NOFILE,
71 /// The maximum size (in bytes) of the stack segment for a process.
72 RLIMIT_STACK,
73
74 #[cfg(target_os = "freebsd")]
75 /// The maximum number of kqueues this user id is allowed to create.
76 RLIMIT_KQUEUES,
77
78 #[cfg(any(target_os = "android", target_os = "linux"))]
79 /// A limit on the combined number of flock locks and fcntl leases that
80 /// this process may establish.
81 RLIMIT_LOCKS,
82
83 #[cfg(any(target_os = "android", target_os = "freebsd", target_os = "openbsd", target_os = "linux"))]
84 /// The maximum size (in bytes) which a process may lock into memory
85 /// using the mlock(2) system call.
86 RLIMIT_MEMLOCK,
87
88 #[cfg(any(target_os = "android", target_os = "linux"))]
89 /// A limit on the number of bytes that can be allocated for POSIX
90 /// message queues for the real user ID of the calling process.
91 RLIMIT_MSGQUEUE,
92
93 #[cfg(any(target_os = "android", target_os = "linux"))]
94 /// A ceiling to which the process's nice value can be raised using
95 /// setpriority or nice.
96 RLIMIT_NICE,
97
98 #[cfg(any(target_os = "android", target_os = "freebsd", target_os = "openbsd", target_os = "linux"))]
99 /// The maximum number of simultaneous processes for this user id.
100 RLIMIT_NPROC,
101
102 #[cfg(target_os = "freebsd")]
103 /// The maximum number of pseudo-terminals this user id is allowed to
104 /// create.
105 RLIMIT_NPTS,
106
107 #[cfg(any(target_os = "android", target_os = "freebsd", target_os = "openbsd", target_os = "linux"))]
108 /// When there is memory pressure and swap is available, prioritize
109 /// eviction of a process' resident pages beyond this amount (in bytes).
110 RLIMIT_RSS,
111
112 #[cfg(any(target_os = "android", target_os = "linux"))]
113 /// A ceiling on the real-time priority that may be set for this process
114 /// using sched_setscheduler and sched_set‐ param.
115 RLIMIT_RTPRIO,
116
117 #[cfg(any(target_os = "linux"))]
118 /// A limit (in microseconds) on the amount of CPU time that a process
119 /// scheduled under a real-time scheduling policy may con‐ sume without
120 /// making a blocking system call.
121 RLIMIT_RTTIME,
122
123 #[cfg(any(target_os = "android", target_os = "linux"))]
124 /// A limit on the number of signals that may be queued for the real
125 /// user ID of the calling process.
126 RLIMIT_SIGPENDING,
127
128 #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))]
129 /// The maximum size (in bytes) of socket buffer usage for this user.
130 RLIMIT_SBSIZE,
131
132 #[cfg(target_os = "freebsd")]
133 /// The maximum size (in bytes) of the swap space that may be reserved
134 /// or used by all of this user id's processes.
135 RLIMIT_SWAP,
136
137 #[cfg(target_os = "freebsd")]
138 /// An alias for RLIMIT_AS.
139 RLIMIT_VMEM,
140 }
141}
142
143/// Get the current processes resource limits
144///
145/// A value of `None` indicates the value equals to `RLIM_INFINITY` which means
146/// there is no limit.
147///
148/// # Parameters
149///
150/// * `resource`: The [`Resource`] that we want to get the limits of.
151///
152/// # Examples
153///
154/// ```
155/// # use nix::sys::resource::{getrlimit, Resource};
156///
157/// let (soft_limit, hard_limit) = getrlimit(Resource::RLIMIT_NOFILE).unwrap();
158/// println!("current soft_limit: {:?}", soft_limit);
159/// println!("current hard_limit: {:?}", hard_limit);
160/// ```
161///
162/// # References
163///
164/// [getrlimit(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/getrlimit.html#tag_16_215)
165///
166/// [`Resource`]: enum.Resource.html
167pub fn getrlimit(resource: Resource) -> Result<(Option<rlim_t>, Option<rlim_t>)> {
168 let mut old_rlim = mem::MaybeUninit::<rlimit>::uninit();
169
170 cfg_if! {
171 if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
172 let res = unsafe { libc::getrlimit(resource as __rlimit_resource_t, old_rlim.as_mut_ptr()) };
173 }else{
174 let res = unsafe { libc::getrlimit(resource as c_int, old_rlim.as_mut_ptr()) };
175 }
176 }
177
178 Errno::result(res).map(|_| {
179 let rlimit { rlim_cur, rlim_max } = unsafe { old_rlim.assume_init() };
180 (Some(rlim_cur), Some(rlim_max))
181 })
182}
183
184/// Set the current processes resource limits
185///
186/// # Parameters
187///
188/// * `resource`: The [`Resource`] that we want to set the limits of.
189/// * `soft_limit`: The value that the kernel enforces for the corresponding
190/// resource. Note: `None` input will be replaced by constant `RLIM_INFINITY`.
191/// * `hard_limit`: The ceiling for the soft limit. Must be lower or equal to
192/// the current hard limit for non-root users. Note: `None` input will be
193/// replaced by constant `RLIM_INFINITY`.
194///
195/// > Note: for some os (linux_gnu), setting hard_limit to `RLIM_INFINITY` can
196/// > results `EPERM` Error. So you will need to set the number explicitly.
197///
198/// # Examples
199///
200/// ```
201/// # use nix::sys::resource::{setrlimit, Resource};
202///
203/// let soft_limit = Some(512);
204/// let hard_limit = Some(1024);
205/// setrlimit(Resource::RLIMIT_NOFILE, soft_limit, hard_limit).unwrap();
206/// ```
207///
208/// # References
209///
210/// [setrlimit(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/getrlimit.html#tag_16_215)
211///
212/// [`Resource`]: enum.Resource.html
213///
214/// Note: `setrlimit` provides a safe wrapper to libc's `setrlimit`.
215pub fn setrlimit(
216 resource: Resource,
217 soft_limit: Option<rlim_t>,
218 hard_limit: Option<rlim_t>,
219) -> Result<()> {
220 let new_rlim = rlimit {
221 rlim_cur: soft_limit.unwrap_or(RLIM_INFINITY),
222 rlim_max: hard_limit.unwrap_or(RLIM_INFINITY),
223 };
224 cfg_if! {
225 if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
226 let res = unsafe { libc::setrlimit(resource as __rlimit_resource_t, &new_rlim as *const rlimit) };
227 }else{
228 let res = unsafe { libc::setrlimit(resource as c_int, &new_rlim as *const rlimit) };
229 }
230 }
231
232 Errno::result(res).map(drop)
233}