1use crate::ffi::CStr;
2use crate::mem::{self, ManuallyDrop};
3use crate::num::NonZero;
4#[cfg(all(target_os = "linux", target_env = "gnu"))]
5use crate::sys::weak::dlsym;
6#[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "nto",))]
7use crate::sys::weak::weak;
8use crate::sys::{os, stack_overflow};
9use crate::time::Duration;
10use crate::{cmp, io, ptr};
11#[cfg(not(any(
12 target_os = "l4re",
13 target_os = "vxworks",
14 target_os = "espidf",
15 target_os = "nuttx"
16)))]
17pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
18#[cfg(target_os = "l4re")]
19pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
20#[cfg(target_os = "vxworks")]
21pub const DEFAULT_MIN_STACK_SIZE: usize = 256 * 1024;
22#[cfg(any(target_os = "espidf", target_os = "nuttx"))]
23pub const DEFAULT_MIN_STACK_SIZE: usize = 0; // 0 indicates that the stack size configured in the ESP-IDF/NuttX menuconfig system should be used
24
25pub struct Thread {
26 id: libc::pthread_t,
27}
28
29// Some platforms may have pthread_t as a pointer in which case we still want
30// a thread to be Send/Sync
31unsafe impl Send for Thread {}
32unsafe impl Sync for Thread {}
33
34impl Thread {
35 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
36 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
37 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
38 let p = Box::into_raw(Box::new(p));
39 let mut native: libc::pthread_t = mem::zeroed();
40 let mut attr: mem::MaybeUninit<libc::pthread_attr_t> = mem::MaybeUninit::uninit();
41 assert_eq!(libc::pthread_attr_init(attr.as_mut_ptr()), 0);
42
43 #[cfg(any(target_os = "espidf", target_os = "nuttx"))]
44 if stack > 0 {
45 // Only set the stack if a non-zero value is passed
46 // 0 is used as an indication that the default stack size configured in the ESP-IDF/NuttX menuconfig system should be used
47 assert_eq!(
48 libc::pthread_attr_setstacksize(
49 attr.as_mut_ptr(),
50 cmp::max(stack, min_stack_size(attr.as_ptr()))
51 ),
52 0
53 );
54 }
55
56 #[cfg(not(any(target_os = "espidf", target_os = "nuttx")))]
57 {
58 let stack_size = cmp::max(stack, min_stack_size(attr.as_ptr()));
59
60 match libc::pthread_attr_setstacksize(attr.as_mut_ptr(), stack_size) {
61 0 => {}
62 n => {
63 assert_eq!(n, libc::EINVAL);
64 // EINVAL means |stack_size| is either too small or not a
65 // multiple of the system page size. Because it's definitely
66 // >= PTHREAD_STACK_MIN, it must be an alignment issue.
67 // Round up to the nearest page and try again.
68 let page_size = os::page_size();
69 let stack_size =
70 (stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);
71 assert_eq!(libc::pthread_attr_setstacksize(attr.as_mut_ptr(), stack_size), 0);
72 }
73 };
74 }
75
76 let ret = libc::pthread_create(&mut native, attr.as_ptr(), thread_start, p as *mut _);
77 // Note: if the thread creation fails and this assert fails, then p will
78 // be leaked. However, an alternative design could cause double-free
79 // which is clearly worse.
80 assert_eq!(libc::pthread_attr_destroy(attr.as_mut_ptr()), 0);
81
82 return if ret != 0 {
83 // The thread failed to start and as a result p was not consumed. Therefore, it is
84 // safe to reconstruct the box so that it gets deallocated.
85 drop(Box::from_raw(p));
86 Err(io::Error::from_raw_os_error(ret))
87 } else {
88 Ok(Thread { id: native })
89 };
90
91 extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
92 unsafe {
93 // Next, set up our stack overflow handler which may get triggered if we run
94 // out of stack.
95 let _handler = stack_overflow::Handler::new();
96 // Finally, let's run some code.
97 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
98 }
99 ptr::null_mut()
100 }
101 }
102
103 pub fn yield_now() {
104 let ret = unsafe { libc::sched_yield() };
105 debug_assert_eq!(ret, 0);
106 }
107
108 #[cfg(target_os = "android")]
109 pub fn set_name(name: &CStr) {
110 const PR_SET_NAME: libc::c_int = 15;
111 unsafe {
112 let res = libc::prctl(
113 PR_SET_NAME,
114 name.as_ptr(),
115 0 as libc::c_ulong,
116 0 as libc::c_ulong,
117 0 as libc::c_ulong,
118 );
119 // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
120 debug_assert_eq!(res, 0);
121 }
122 }
123
124 #[cfg(any(
125 target_os = "linux",
126 target_os = "freebsd",
127 target_os = "dragonfly",
128 target_os = "nuttx",
129 target_os = "cygwin"
130 ))]
131 pub fn set_name(name: &CStr) {
132 unsafe {
133 cfg_if::cfg_if! {
134 if #[cfg(any(target_os = "linux", target_os = "cygwin"))] {
135 // Linux and Cygwin limits the allowed length of the name.
136 const TASK_COMM_LEN: usize = 16;
137 let name = truncate_cstr::<{ TASK_COMM_LEN }>(name);
138 } else {
139 // FreeBSD, DragonFly BSD and NuttX do not enforce length limits.
140 }
141 };
142 // Available since glibc 2.12, musl 1.1.16, and uClibc 1.0.20 for Linux,
143 // FreeBSD 12.2 and 13.0, and DragonFly BSD 6.0.
144 let res = libc::pthread_setname_np(libc::pthread_self(), name.as_ptr());
145 // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
146 debug_assert_eq!(res, 0);
147 }
148 }
149
150 #[cfg(target_os = "openbsd")]
151 pub fn set_name(name: &CStr) {
152 unsafe {
153 libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
154 }
155 }
156
157 #[cfg(target_vendor = "apple")]
158 pub fn set_name(name: &CStr) {
159 unsafe {
160 let name = truncate_cstr::<{ libc::MAXTHREADNAMESIZE }>(name);
161 let res = libc::pthread_setname_np(name.as_ptr());
162 // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
163 debug_assert_eq!(res, 0);
164 }
165 }
166
167 #[cfg(target_os = "netbsd")]
168 pub fn set_name(name: &CStr) {
169 unsafe {
170 let res = libc::pthread_setname_np(
171 libc::pthread_self(),
172 c"%s".as_ptr(),
173 name.as_ptr() as *mut libc::c_void,
174 );
175 debug_assert_eq!(res, 0);
176 }
177 }
178
179 #[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "nto"))]
180 pub fn set_name(name: &CStr) {
181 weak!(
182 fn pthread_setname_np(
183 thread: libc::pthread_t,
184 name: *const libc::c_char,
185 ) -> libc::c_int;
186 );
187
188 if let Some(f) = pthread_setname_np.get() {
189 #[cfg(target_os = "nto")]
190 const THREAD_NAME_MAX: usize = libc::_NTO_THREAD_NAME_MAX as usize;
191 #[cfg(any(target_os = "solaris", target_os = "illumos"))]
192 const THREAD_NAME_MAX: usize = 32;
193
194 let name = truncate_cstr::<{ THREAD_NAME_MAX }>(name);
195 let res = unsafe { f(libc::pthread_self(), name.as_ptr()) };
196 debug_assert_eq!(res, 0);
197 }
198 }
199
200 #[cfg(target_os = "fuchsia")]
201 pub fn set_name(name: &CStr) {
202 use super::fuchsia::*;
203 unsafe {
204 zx_object_set_property(
205 zx_thread_self(),
206 ZX_PROP_NAME,
207 name.as_ptr() as *const libc::c_void,
208 name.to_bytes().len(),
209 );
210 }
211 }
212
213 #[cfg(target_os = "haiku")]
214 pub fn set_name(name: &CStr) {
215 unsafe {
216 let thread_self = libc::find_thread(ptr::null_mut());
217 let res = libc::rename_thread(thread_self, name.as_ptr());
218 // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
219 debug_assert_eq!(res, libc::B_OK);
220 }
221 }
222
223 #[cfg(target_os = "vxworks")]
224 pub fn set_name(name: &CStr) {
225 let mut name = truncate_cstr::<{ libc::VX_TASK_RENAME_LENGTH - 1 }>(name);
226 let res = unsafe { libc::taskNameSet(libc::taskIdSelf(), name.as_mut_ptr()) };
227 debug_assert_eq!(res, libc::OK);
228 }
229
230 #[cfg(any(
231 target_env = "newlib",
232 target_os = "l4re",
233 target_os = "emscripten",
234 target_os = "redox",
235 target_os = "hurd",
236 target_os = "aix",
237 ))]
238 pub fn set_name(_name: &CStr) {
239 // Newlib and Emscripten have no way to set a thread name.
240 }
241
242 #[cfg(not(target_os = "espidf"))]
243 pub fn sleep(dur: Duration) {
244 let mut secs = dur.as_secs();
245 let mut nsecs = dur.subsec_nanos() as _;
246
247 // If we're awoken with a signal then the return value will be -1 and
248 // nanosleep will fill in `ts` with the remaining time.
249 unsafe {
250 while secs > 0 || nsecs > 0 {
251 let mut ts = libc::timespec {
252 tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t,
253 tv_nsec: nsecs,
254 };
255 secs -= ts.tv_sec as u64;
256 let ts_ptr = &raw mut ts;
257 if libc::nanosleep(ts_ptr, ts_ptr) == -1 {
258 assert_eq!(os::errno(), libc::EINTR);
259 secs += ts.tv_sec as u64;
260 nsecs = ts.tv_nsec;
261 } else {
262 nsecs = 0;
263 }
264 }
265 }
266 }
267
268 #[cfg(target_os = "espidf")]
269 pub fn sleep(dur: Duration) {
270 // ESP-IDF does not have `nanosleep`, so we use `usleep` instead.
271 // As per the documentation of `usleep`, it is expected to support
272 // sleep times as big as at least up to 1 second.
273 //
274 // ESP-IDF does support almost up to `u32::MAX`, but due to a potential integer overflow in its
275 // `usleep` implementation
276 // (https://github.com/espressif/esp-idf/blob/d7ca8b94c852052e3bc33292287ef4dd62c9eeb1/components/newlib/time.c#L210),
277 // we limit the sleep time to the maximum one that would not cause the underlying `usleep` implementation to overflow
278 // (`portTICK_PERIOD_MS` can be anything between 1 to 1000, and is 10 by default).
279 const MAX_MICROS: u32 = u32::MAX - 1_000_000 - 1;
280
281 // Add any nanoseconds smaller than a microsecond as an extra microsecond
282 // so as to comply with the `std::thread::sleep` contract which mandates
283 // implementations to sleep for _at least_ the provided `dur`.
284 // We can't overflow `micros` as it is a `u128`, while `Duration` is a pair of
285 // (`u64` secs, `u32` nanos), where the nanos are strictly smaller than 1 second
286 // (i.e. < 1_000_000_000)
287 let mut micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };
288
289 while micros > 0 {
290 let st = if micros > MAX_MICROS as u128 { MAX_MICROS } else { micros as u32 };
291 unsafe {
292 libc::usleep(st);
293 }
294
295 micros -= st as u128;
296 }
297 }
298
299 pub fn join(self) {
300 let id = self.into_id();
301 let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
302 assert!(ret == 0, "failed to join thread: {}", io::Error::from_raw_os_error(ret));
303 }
304
305 pub fn id(&self) -> libc::pthread_t {
306 self.id
307 }
308
309 pub fn into_id(self) -> libc::pthread_t {
310 ManuallyDrop::new(self).id
311 }
312}
313
314impl Drop for Thread {
315 fn drop(&mut self) {
316 let ret: i32 = unsafe { libc::pthread_detach(self.id) };
317 debug_assert_eq!(ret, 0);
318 }
319}
320
321#[cfg(any(
322 target_os = "linux",
323 target_os = "nto",
324 target_os = "solaris",
325 target_os = "illumos",
326 target_os = "vxworks",
327 target_os = "cygwin",
328 target_vendor = "apple",
329))]
330fn truncate_cstr<const MAX_WITH_NUL: usize>(cstr: &CStr) -> [libc::c_char; MAX_WITH_NUL] {
331 let mut result: [i8; MAX_WITH_NUL] = [0; MAX_WITH_NUL];
332 for (src: &u8, dst: &mut i8) in cstr.to_bytes().iter().zip(&mut result[..MAX_WITH_NUL - 1]) {
333 *dst = *src as libc::c_char;
334 }
335 result
336}
337
338pub fn available_parallelism() -> io::Result<NonZero<usize>> {
339 cfg_if::cfg_if! {
340 if #[cfg(any(
341 target_os = "android",
342 target_os = "emscripten",
343 target_os = "fuchsia",
344 target_os = "hurd",
345 target_os = "linux",
346 target_os = "aix",
347 target_vendor = "apple",
348 target_os = "cygwin",
349 ))] {
350 #[allow(unused_assignments)]
351 #[allow(unused_mut)]
352 let mut quota = usize::MAX;
353
354 #[cfg(any(target_os = "android", target_os = "linux"))]
355 {
356 quota = cgroups::quota().max(1);
357 let mut set: libc::cpu_set_t = unsafe { mem::zeroed() };
358 unsafe {
359 if libc::sched_getaffinity(0, size_of::<libc::cpu_set_t>(), &mut set) == 0 {
360 let count = libc::CPU_COUNT(&set) as usize;
361 let count = count.min(quota);
362
363 // According to sched_getaffinity's API it should always be non-zero, but
364 // some old MIPS kernels were buggy and zero-initialized the mask if
365 // none was explicitly set.
366 // In that case we use the sysconf fallback.
367 if let Some(count) = NonZero::new(count) {
368 return Ok(count)
369 }
370 }
371 }
372 }
373 match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
374 -1 => Err(io::Error::last_os_error()),
375 0 => Err(io::Error::UNKNOWN_THREAD_COUNT),
376 cpus => {
377 let count = cpus as usize;
378 // Cover the unusual situation where we were able to get the quota but not the affinity mask
379 let count = count.min(quota);
380 Ok(unsafe { NonZero::new_unchecked(count) })
381 }
382 }
383 } else if #[cfg(any(
384 target_os = "freebsd",
385 target_os = "dragonfly",
386 target_os = "openbsd",
387 target_os = "netbsd",
388 ))] {
389 use crate::ptr;
390
391 #[cfg(target_os = "freebsd")]
392 {
393 let mut set: libc::cpuset_t = unsafe { mem::zeroed() };
394 unsafe {
395 if libc::cpuset_getaffinity(
396 libc::CPU_LEVEL_WHICH,
397 libc::CPU_WHICH_PID,
398 -1,
399 size_of::<libc::cpuset_t>(),
400 &mut set,
401 ) == 0 {
402 let count = libc::CPU_COUNT(&set) as usize;
403 if count > 0 {
404 return Ok(NonZero::new_unchecked(count));
405 }
406 }
407 }
408 }
409
410 #[cfg(target_os = "netbsd")]
411 {
412 unsafe {
413 let set = libc::_cpuset_create();
414 if !set.is_null() {
415 let mut count: usize = 0;
416 if libc::pthread_getaffinity_np(libc::pthread_self(), libc::_cpuset_size(set), set) == 0 {
417 for i in 0..libc::cpuid_t::MAX {
418 match libc::_cpuset_isset(i, set) {
419 -1 => break,
420 0 => continue,
421 _ => count = count + 1,
422 }
423 }
424 }
425 libc::_cpuset_destroy(set);
426 if let Some(count) = NonZero::new(count) {
427 return Ok(count);
428 }
429 }
430 }
431 }
432
433 let mut cpus: libc::c_uint = 0;
434 let mut cpus_size = size_of_val(&cpus);
435
436 unsafe {
437 cpus = libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as libc::c_uint;
438 }
439
440 // Fallback approach in case of errors or no hardware threads.
441 if cpus < 1 {
442 let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
443 let res = unsafe {
444 libc::sysctl(
445 mib.as_mut_ptr(),
446 2,
447 (&raw mut cpus) as *mut _,
448 (&raw mut cpus_size) as *mut _,
449 ptr::null_mut(),
450 0,
451 )
452 };
453
454 // Handle errors if any.
455 if res == -1 {
456 return Err(io::Error::last_os_error());
457 } else if cpus == 0 {
458 return Err(io::Error::UNKNOWN_THREAD_COUNT);
459 }
460 }
461
462 Ok(unsafe { NonZero::new_unchecked(cpus as usize) })
463 } else if #[cfg(target_os = "nto")] {
464 unsafe {
465 use libc::_syspage_ptr;
466 if _syspage_ptr.is_null() {
467 Err(io::const_error!(io::ErrorKind::NotFound, "no syspage available"))
468 } else {
469 let cpus = (*_syspage_ptr).num_cpu;
470 NonZero::new(cpus as usize)
471 .ok_or(io::Error::UNKNOWN_THREAD_COUNT)
472 }
473 }
474 } else if #[cfg(any(target_os = "solaris", target_os = "illumos"))] {
475 let mut cpus = 0u32;
476 if unsafe { libc::pset_info(libc::PS_MYID, core::ptr::null_mut(), &mut cpus, core::ptr::null_mut()) } != 0 {
477 return Err(io::Error::UNKNOWN_THREAD_COUNT);
478 }
479 Ok(unsafe { NonZero::new_unchecked(cpus as usize) })
480 } else if #[cfg(target_os = "haiku")] {
481 // system_info cpu_count field gets the static data set at boot time with `smp_set_num_cpus`
482 // `get_system_info` calls then `smp_get_num_cpus`
483 unsafe {
484 let mut sinfo: libc::system_info = crate::mem::zeroed();
485 let res = libc::get_system_info(&mut sinfo);
486
487 if res != libc::B_OK {
488 return Err(io::Error::UNKNOWN_THREAD_COUNT);
489 }
490
491 Ok(NonZero::new_unchecked(sinfo.cpu_count as usize))
492 }
493 } else if #[cfg(target_os = "vxworks")] {
494 // Note: there is also `vxCpuConfiguredGet`, closer to _SC_NPROCESSORS_CONF
495 // expectations than the actual cores availability.
496 unsafe extern "C" {
497 fn vxCpuEnabledGet() -> libc::cpuset_t;
498 }
499
500 // SAFETY: `vxCpuEnabledGet` always fetches a mask with at least one bit set
501 unsafe{
502 let set = vxCpuEnabledGet();
503 Ok(NonZero::new_unchecked(set.count_ones() as usize))
504 }
505 } else {
506 // FIXME: implement on Redox, l4re
507 Err(io::const_error!(io::ErrorKind::Unsupported, "getting the number of hardware threads is not supported on the target platform"))
508 }
509 }
510}
511
512#[cfg(any(target_os = "android", target_os = "linux"))]
513mod cgroups {
514 //! Currently not covered
515 //! * cgroup v2 in non-standard mountpoints
516 //! * paths containing control characters or spaces, since those would be escaped in procfs
517 //! output and we don't unescape
518
519 use crate::borrow::Cow;
520 use crate::ffi::OsString;
521 use crate::fs::{File, exists};
522 use crate::io::{BufRead, Read};
523 use crate::os::unix::ffi::OsStringExt;
524 use crate::path::{Path, PathBuf};
525 use crate::str::from_utf8;
526
527 #[derive(PartialEq)]
528 enum Cgroup {
529 V1,
530 V2,
531 }
532
533 /// Returns cgroup CPU quota in core-equivalents, rounded down or usize::MAX if the quota cannot
534 /// be determined or is not set.
535 pub(super) fn quota() -> usize {
536 let mut quota = usize::MAX;
537 if cfg!(miri) {
538 // Attempting to open a file fails under default flags due to isolation.
539 // And Miri does not have parallelism anyway.
540 return quota;
541 }
542
543 let _: Option<()> = try {
544 let mut buf = Vec::with_capacity(128);
545 // find our place in the cgroup hierarchy
546 File::open("/proc/self/cgroup").ok()?.read_to_end(&mut buf).ok()?;
547 let (cgroup_path, version) =
548 buf.split(|&c| c == b'\n').fold(None, |previous, line| {
549 let mut fields = line.splitn(3, |&c| c == b':');
550 // 2nd field is a list of controllers for v1 or empty for v2
551 let version = match fields.nth(1) {
552 Some(b"") => Cgroup::V2,
553 Some(controllers)
554 if from_utf8(controllers)
555 .is_ok_and(|c| c.split(',').any(|c| c == "cpu")) =>
556 {
557 Cgroup::V1
558 }
559 _ => return previous,
560 };
561
562 // already-found v1 trumps v2 since it explicitly specifies its controllers
563 if previous.is_some() && version == Cgroup::V2 {
564 return previous;
565 }
566
567 let path = fields.last()?;
568 // skip leading slash
569 Some((path[1..].to_owned(), version))
570 })?;
571 let cgroup_path = PathBuf::from(OsString::from_vec(cgroup_path));
572
573 quota = match version {
574 Cgroup::V1 => quota_v1(cgroup_path),
575 Cgroup::V2 => quota_v2(cgroup_path),
576 };
577 };
578
579 quota
580 }
581
582 fn quota_v2(group_path: PathBuf) -> usize {
583 let mut quota = usize::MAX;
584
585 let mut path = PathBuf::with_capacity(128);
586 let mut read_buf = String::with_capacity(20);
587
588 // standard mount location defined in file-hierarchy(7) manpage
589 let cgroup_mount = "/sys/fs/cgroup";
590
591 path.push(cgroup_mount);
592 path.push(&group_path);
593
594 path.push("cgroup.controllers");
595
596 // skip if we're not looking at cgroup2
597 if matches!(exists(&path), Err(_) | Ok(false)) {
598 return usize::MAX;
599 };
600
601 path.pop();
602
603 let _: Option<()> = try {
604 while path.starts_with(cgroup_mount) {
605 path.push("cpu.max");
606
607 read_buf.clear();
608
609 if File::open(&path).and_then(|mut f| f.read_to_string(&mut read_buf)).is_ok() {
610 let raw_quota = read_buf.lines().next()?;
611 let mut raw_quota = raw_quota.split(' ');
612 let limit = raw_quota.next()?;
613 let period = raw_quota.next()?;
614 match (limit.parse::<usize>(), period.parse::<usize>()) {
615 (Ok(limit), Ok(period)) if period > 0 => {
616 quota = quota.min(limit / period);
617 }
618 _ => {}
619 }
620 }
621
622 path.pop(); // pop filename
623 path.pop(); // pop dir
624 }
625 };
626
627 quota
628 }
629
630 fn quota_v1(group_path: PathBuf) -> usize {
631 let mut quota = usize::MAX;
632 let mut path = PathBuf::with_capacity(128);
633 let mut read_buf = String::with_capacity(20);
634
635 // Hardcode commonly used locations mentioned in the cgroups(7) manpage
636 // if that doesn't work scan mountinfo and adjust `group_path` for bind-mounts
637 let mounts: &[fn(&Path) -> Option<(_, &Path)>] = &[
638 |p| Some((Cow::Borrowed("/sys/fs/cgroup/cpu"), p)),
639 |p| Some((Cow::Borrowed("/sys/fs/cgroup/cpu,cpuacct"), p)),
640 // this can be expensive on systems with tons of mountpoints
641 // but we only get to this point when /proc/self/cgroups explicitly indicated
642 // this process belongs to a cpu-controller cgroup v1 and the defaults didn't work
643 find_mountpoint,
644 ];
645
646 for mount in mounts {
647 let Some((mount, group_path)) = mount(&group_path) else { continue };
648
649 path.clear();
650 path.push(mount.as_ref());
651 path.push(&group_path);
652
653 // skip if we guessed the mount incorrectly
654 if matches!(exists(&path), Err(_) | Ok(false)) {
655 continue;
656 }
657
658 while path.starts_with(mount.as_ref()) {
659 let mut parse_file = |name| {
660 path.push(name);
661 read_buf.clear();
662
663 let f = File::open(&path);
664 path.pop(); // restore buffer before any early returns
665 f.ok()?.read_to_string(&mut read_buf).ok()?;
666 let parsed = read_buf.trim().parse::<usize>().ok()?;
667
668 Some(parsed)
669 };
670
671 let limit = parse_file("cpu.cfs_quota_us");
672 let period = parse_file("cpu.cfs_period_us");
673
674 match (limit, period) {
675 (Some(limit), Some(period)) if period > 0 => quota = quota.min(limit / period),
676 _ => {}
677 }
678
679 path.pop();
680 }
681
682 // we passed the try_exists above so we should have traversed the correct hierarchy
683 // when reaching this line
684 break;
685 }
686
687 quota
688 }
689
690 /// Scan mountinfo for cgroup v1 mountpoint with a cpu controller
691 ///
692 /// If the cgroupfs is a bind mount then `group_path` is adjusted to skip
693 /// over the already-included prefix
694 fn find_mountpoint(group_path: &Path) -> Option<(Cow<'static, str>, &Path)> {
695 let mut reader = File::open_buffered("/proc/self/mountinfo").ok()?;
696 let mut line = String::with_capacity(256);
697 loop {
698 line.clear();
699 if reader.read_line(&mut line).ok()? == 0 {
700 break;
701 }
702
703 let line = line.trim();
704 let mut items = line.split(' ');
705
706 let sub_path = items.nth(3)?;
707 let mount_point = items.next()?;
708 let mount_opts = items.next_back()?;
709 let filesystem_type = items.nth_back(1)?;
710
711 if filesystem_type != "cgroup" || !mount_opts.split(',').any(|opt| opt == "cpu") {
712 // not a cgroup / not a cpu-controller
713 continue;
714 }
715
716 let sub_path = Path::new(sub_path).strip_prefix("/").ok()?;
717
718 if !group_path.starts_with(sub_path) {
719 // this is a bind-mount and the bound subdirectory
720 // does not contain the cgroup this process belongs to
721 continue;
722 }
723
724 let trimmed_group_path = group_path.strip_prefix(sub_path).ok()?;
725
726 return Some((Cow::Owned(mount_point.to_owned()), trimmed_group_path));
727 }
728
729 None
730 }
731}
732
733// glibc >= 2.15 has a __pthread_get_minstack() function that returns
734// PTHREAD_STACK_MIN plus bytes needed for thread-local storage.
735// We need that information to avoid blowing up when a small stack
736// is created in an application with big thread-local storage requirements.
737// See #6233 for rationale and details.
738#[cfg(all(target_os = "linux", target_env = "gnu"))]
739unsafe fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
740 // We use dlsym to avoid an ELF version dependency on GLIBC_PRIVATE. (#23628)
741 // We shouldn't really be using such an internal symbol, but there's currently
742 // no other way to account for the TLS size.
743 dlsym!(
744 fn __pthread_get_minstack(attr: *const libc::pthread_attr_t) -> libc::size_t;
745 );
746
747 match __pthread_get_minstack.get() {
748 None => libc::PTHREAD_STACK_MIN,
749 Some(f) => unsafe { f(attr) },
750 }
751}
752
753// No point in looking up __pthread_get_minstack() on non-glibc platforms.
754#[cfg(all(
755 not(all(target_os = "linux", target_env = "gnu")),
756 not(any(target_os = "netbsd", target_os = "nuttx"))
757))]
758unsafe fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
759 libc::PTHREAD_STACK_MIN
760}
761
762#[cfg(any(target_os = "netbsd", target_os = "nuttx"))]
763unsafe fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
764 static STACK: crate::sync::OnceLock<usize> = crate::sync::OnceLock::new();
765
766 *STACK.get_or_init(|| {
767 let mut stack = unsafe { libc::sysconf(libc::_SC_THREAD_STACK_MIN) };
768 if stack < 0 {
769 stack = 2048; // just a guess
770 }
771
772 stack as usize
773 })
774}
775