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thread.rs
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thread.rs
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use crate::cmp;
use crate::ffi::CStr;
use crate::io;
use crate::mem;
use crate::num::NonZeroUsize;
use crate::ptr;
use crate::sys::{os, stack_overflow};
use crate::time::Duration;
#[cfg(all(target_os = "linux", target_env = "gnu"))]
use crate::sys::weak::dlsym;
#[cfg(any(target_os = "solaris", target_os = "illumos"))]
use crate::sys::weak::weak;
#[cfg(not(any(target_os = "l4re", target_os = "vxworks", target_os = "espidf")))]
pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
#[cfg(target_os = "l4re")]
pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
#[cfg(target_os = "vxworks")]
pub const DEFAULT_MIN_STACK_SIZE: usize = 256 * 1024;
#[cfg(target_os = "espidf")]
pub const DEFAULT_MIN_STACK_SIZE: usize = 0; // 0 indicates that the stack size configured in the ESP-IDF menuconfig system should be used
#[cfg(target_os = "fuchsia")]
mod zircon {
type zx_handle_t = u32;
type zx_status_t = i32;
pub const ZX_PROP_NAME: u32 = 3;
extern "C" {
pub fn zx_object_set_property(
handle: zx_handle_t,
property: u32,
value: *const libc::c_void,
value_size: libc::size_t,
) -> zx_status_t;
pub fn zx_thread_self() -> zx_handle_t;
}
}
pub struct Thread {
id: libc::pthread_t,
}
// Some platforms may have pthread_t as a pointer in which case we still want
// a thread to be Send/Sync
unsafe impl Send for Thread {}
unsafe impl Sync for Thread {}
impl Thread {
// unsafe: see thread::Builder::spawn_unchecked for safety requirements
pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
let p = Box::into_raw(box p);
let mut native: libc::pthread_t = mem::zeroed();
let mut attr: libc::pthread_attr_t = mem::zeroed();
assert_eq!(libc::pthread_attr_init(&mut attr), 0);
#[cfg(target_os = "espidf")]
if stack > 0 {
// Only set the stack if a non-zero value is passed
// 0 is used as an indication that the default stack size configured in the ESP-IDF menuconfig system should be used
assert_eq!(
libc::pthread_attr_setstacksize(&mut attr, cmp::max(stack, min_stack_size(&attr))),
0
);
}
#[cfg(not(target_os = "espidf"))]
{
let stack_size = cmp::max(stack, min_stack_size(&attr));
match libc::pthread_attr_setstacksize(&mut attr, stack_size) {
0 => {}
n => {
assert_eq!(n, libc::EINVAL);
// EINVAL means |stack_size| is either too small or not a
// multiple of the system page size. Because it's definitely
// >= PTHREAD_STACK_MIN, it must be an alignment issue.
// Round up to the nearest page and try again.
let page_size = os::page_size();
let stack_size =
(stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);
assert_eq!(libc::pthread_attr_setstacksize(&mut attr, stack_size), 0);
}
};
}
let ret = libc::pthread_create(&mut native, &attr, thread_start, p as *mut _);
// Note: if the thread creation fails and this assert fails, then p will
// be leaked. However, an alternative design could cause double-free
// which is clearly worse.
assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
return if ret != 0 {
// The thread failed to start and as a result p was not consumed. Therefore, it is
// safe to reconstruct the box so that it gets deallocated.
drop(Box::from_raw(p));
Err(io::Error::from_raw_os_error(ret))
} else {
Ok(Thread { id: native })
};
extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
unsafe {
// Next, set up our stack overflow handler which may get triggered if we run
// out of stack.
let _handler = stack_overflow::Handler::new();
// Finally, let's run some code.
Box::from_raw(main as *mut Box<dyn FnOnce()>)();
}
ptr::null_mut()
}
}
pub fn yield_now() {
let ret = unsafe { libc::sched_yield() };
debug_assert_eq!(ret, 0);
}
#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn set_name(name: &CStr) {
const PR_SET_NAME: libc::c_int = 15;
// pthread wrapper only appeared in glibc 2.12, so we use syscall
// directly.
unsafe {
libc::prctl(PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0);
}
}
#[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))]
pub fn set_name(name: &CStr) {
unsafe {
libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
}
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
pub fn set_name(name: &CStr) {
unsafe {
libc::pthread_setname_np(name.as_ptr());
}
}
#[cfg(target_os = "netbsd")]
pub fn set_name(name: &CStr) {
use crate::ffi::CString;
let cname = CString::new(&b"%s"[..]).unwrap();
unsafe {
libc::pthread_setname_np(
libc::pthread_self(),
cname.as_ptr(),
name.as_ptr() as *mut libc::c_void,
);
}
}
#[cfg(any(target_os = "solaris", target_os = "illumos"))]
pub fn set_name(name: &CStr) {
weak! {
fn pthread_setname_np(
libc::pthread_t, *const libc::c_char
) -> libc::c_int
}
if let Some(f) = pthread_setname_np.get() {
unsafe {
f(libc::pthread_self(), name.as_ptr());
}
}
}
#[cfg(target_os = "fuchsia")]
pub fn set_name(name: &CStr) {
use self::zircon::*;
unsafe {
zx_object_set_property(
zx_thread_self(),
ZX_PROP_NAME,
name.as_ptr() as *const libc::c_void,
name.to_bytes().len(),
);
}
}
#[cfg(target_os = "haiku")]
pub fn set_name(name: &CStr) {
unsafe {
let thread_self = libc::find_thread(ptr::null_mut());
libc::rename_thread(thread_self, name.as_ptr());
}
}
#[cfg(any(
target_env = "newlib",
target_os = "l4re",
target_os = "emscripten",
target_os = "redox",
target_os = "vxworks"
))]
pub fn set_name(_name: &CStr) {
// Newlib, Emscripten, and VxWorks have no way to set a thread name.
}
#[cfg(not(target_os = "espidf"))]
pub fn sleep(dur: Duration) {
let mut secs = dur.as_secs();
let mut nsecs = dur.subsec_nanos() as _;
// If we're awoken with a signal then the return value will be -1 and
// nanosleep will fill in `ts` with the remaining time.
unsafe {
while secs > 0 || nsecs > 0 {
let mut ts = libc::timespec {
tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t,
tv_nsec: nsecs,
};
secs -= ts.tv_sec as u64;
let ts_ptr = &mut ts as *mut _;
if libc::nanosleep(ts_ptr, ts_ptr) == -1 {
assert_eq!(os::errno(), libc::EINTR);
secs += ts.tv_sec as u64;
nsecs = ts.tv_nsec;
} else {
nsecs = 0;
}
}
}
}
#[cfg(target_os = "espidf")]
pub fn sleep(dur: Duration) {
let mut micros = dur.as_micros();
unsafe {
while micros > 0 {
let st = if micros > u32::MAX as u128 { u32::MAX } else { micros as u32 };
libc::usleep(st);
micros -= st as u128;
}
}
}
pub fn join(self) {
unsafe {
let ret = libc::pthread_join(self.id, ptr::null_mut());
mem::forget(self);
assert!(ret == 0, "failed to join thread: {}", io::Error::from_raw_os_error(ret));
}
}
pub fn id(&self) -> libc::pthread_t {
self.id
}
pub fn into_id(self) -> libc::pthread_t {
let id = self.id;
mem::forget(self);
id
}
}
impl Drop for Thread {
fn drop(&mut self) {
let ret = unsafe { libc::pthread_detach(self.id) };
debug_assert_eq!(ret, 0);
}
}
pub fn available_parallelism() -> io::Result<NonZeroUsize> {
cfg_if::cfg_if! {
if #[cfg(any(
target_os = "android",
target_os = "emscripten",
target_os = "fuchsia",
target_os = "ios",
target_os = "linux",
target_os = "macos",
target_os = "solaris",
target_os = "illumos",
))] {
#[cfg(any(target_os = "android", target_os = "linux"))]
{
let quota = cgroup2_quota().max(1);
let mut set: libc::cpu_set_t = unsafe { mem::zeroed() };
unsafe {
if libc::sched_getaffinity(0, mem::size_of::<libc::cpu_set_t>(), &mut set) == 0 {
let count = libc::CPU_COUNT(&set) as usize;
let count = count.min(quota);
// SAFETY: affinity mask can't be empty and the quota gets clamped to a minimum of 1
return Ok(NonZeroUsize::new_unchecked(count));
}
}
}
match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
-1 => Err(io::Error::last_os_error()),
0 => Err(io::const_io_error!(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform")),
cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) }),
}
} else if #[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "netbsd"))] {
use crate::ptr;
let mut cpus: libc::c_uint = 0;
let mut cpus_size = crate::mem::size_of_val(&cpus);
unsafe {
cpus = libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as libc::c_uint;
}
// Fallback approach in case of errors or no hardware threads.
if cpus < 1 {
let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
let res = unsafe {
libc::sysctl(
mib.as_mut_ptr(),
2,
&mut cpus as *mut _ as *mut _,
&mut cpus_size as *mut _ as *mut _,
ptr::null_mut(),
0,
)
};
// Handle errors if any.
if res == -1 {
return Err(io::Error::last_os_error());
} else if cpus == 0 {
return Err(io::const_io_error!(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"));
}
}
Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) })
} else if #[cfg(target_os = "openbsd")] {
use crate::ptr;
let mut cpus: libc::c_uint = 0;
let mut cpus_size = crate::mem::size_of_val(&cpus);
let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
let res = unsafe {
libc::sysctl(
mib.as_mut_ptr(),
2,
&mut cpus as *mut _ as *mut _,
&mut cpus_size as *mut _ as *mut _,
ptr::null_mut(),
0,
)
};
// Handle errors if any.
if res == -1 {
return Err(io::Error::last_os_error());
} else if cpus == 0 {
return Err(io::const_io_error!(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"));
}
Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) })
} else if #[cfg(target_os = "haiku")] {
// system_info cpu_count field gets the static data set at boot time with `smp_set_num_cpus`
// `get_system_info` calls then `smp_get_num_cpus`
unsafe {
let mut sinfo: libc::system_info = crate::mem::zeroed();
let res = libc::get_system_info(&mut sinfo);
if res != libc::B_OK {
return Err(io::const_io_error!(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"));
}
Ok(NonZeroUsize::new_unchecked(sinfo.cpu_count as usize))
}
} else {
// FIXME: implement on vxWorks, Redox, l4re
Err(io::const_io_error!(io::ErrorKind::Unsupported, "Getting the number of hardware threads is not supported on the target platform"))
}
}
}
/// Returns cgroup CPU quota in core-equivalents, rounded down, or usize::MAX if the quota cannot
/// be determined or is not set.
#[cfg(any(target_os = "android", target_os = "linux"))]
fn cgroup2_quota() -> usize {
use crate::ffi::OsString;
use crate::fs::{try_exists, File};
use crate::io::Read;
use crate::os::unix::ffi::OsStringExt;
use crate::path::PathBuf;
let mut quota = usize::MAX;
if cfg!(miri) {
// Attempting to open a file fails under default flags due to isolation.
// And Miri does not have parallelism anyway.
return quota;
}
let _: Option<()> = try {
let mut buf = Vec::with_capacity(128);
// find our place in the cgroup hierarchy
File::open("/proc/self/cgroup").ok()?.read_to_end(&mut buf).ok()?;
let cgroup_path = buf
.split(|&c| c == b'\n')
.filter_map(|line| {
let mut fields = line.splitn(3, |&c| c == b':');
// expect cgroupv2 which has an empty 2nd field
if fields.nth(1) != Some(b"") {
return None;
}
let path = fields.last()?;
// skip leading slash
Some(path[1..].to_owned())
})
.next()?;
let cgroup_path = PathBuf::from(OsString::from_vec(cgroup_path));
let mut path = PathBuf::with_capacity(128);
let mut read_buf = String::with_capacity(20);
let cgroup_mount = "/sys/fs/cgroup";
path.push(cgroup_mount);
path.push(&cgroup_path);
path.push("cgroup.controllers");
// skip if we're not looking at cgroup2
if matches!(try_exists(&path), Err(_) | Ok(false)) {
return usize::MAX;
};
path.pop();
while path.starts_with(cgroup_mount) {
path.push("cpu.max");
read_buf.clear();
if File::open(&path).and_then(|mut f| f.read_to_string(&mut read_buf)).is_ok() {
let raw_quota = read_buf.lines().next()?;
let mut raw_quota = raw_quota.split(' ');
let limit = raw_quota.next()?;
let period = raw_quota.next()?;
match (limit.parse::<usize>(), period.parse::<usize>()) {
(Ok(limit), Ok(period)) => {
quota = quota.min(limit / period);
}
_ => {}
}
}
path.pop(); // pop filename
path.pop(); // pop dir
}
};
quota
}
#[cfg(all(
not(target_os = "linux"),
not(target_os = "freebsd"),
not(target_os = "macos"),
not(target_os = "netbsd"),
not(target_os = "openbsd"),
not(target_os = "solaris")
))]
#[cfg_attr(test, allow(dead_code))]
pub mod guard {
use crate::ops::Range;
pub type Guard = Range<usize>;
pub unsafe fn current() -> Option<Guard> {
None
}
pub unsafe fn init() -> Option<Guard> {
None
}
}
#[cfg(any(
target_os = "linux",
target_os = "freebsd",
target_os = "macos",
target_os = "netbsd",
target_os = "openbsd",
target_os = "solaris"
))]
#[cfg_attr(test, allow(dead_code))]
pub mod guard {
use libc::{mmap, mprotect};
use libc::{MAP_ANON, MAP_FAILED, MAP_FIXED, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE};
use crate::io;
use crate::ops::Range;
use crate::sync::atomic::{AtomicUsize, Ordering};
use crate::sys::os;
// This is initialized in init() and only read from after
static PAGE_SIZE: AtomicUsize = AtomicUsize::new(0);
pub type Guard = Range<usize>;
#[cfg(target_os = "solaris")]
unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
let mut current_stack: libc::stack_t = crate::mem::zeroed();
assert_eq!(libc::stack_getbounds(&mut current_stack), 0);
Some(current_stack.ss_sp)
}
#[cfg(target_os = "macos")]
unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
let th = libc::pthread_self();
let stackaddr =
libc::pthread_get_stackaddr_np(th) as usize - libc::pthread_get_stacksize_np(th);
Some(stackaddr as *mut libc::c_void)
}
#[cfg(target_os = "openbsd")]
unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
let mut current_stack: libc::stack_t = crate::mem::zeroed();
assert_eq!(libc::pthread_stackseg_np(libc::pthread_self(), &mut current_stack), 0);
let stackaddr = if libc::pthread_main_np() == 1 {
// main thread
current_stack.ss_sp as usize - current_stack.ss_size + PAGE_SIZE.load(Ordering::Relaxed)
} else {
// new thread
current_stack.ss_sp as usize - current_stack.ss_size
};
Some(stackaddr as *mut libc::c_void)
}
#[cfg(any(
target_os = "android",
target_os = "freebsd",
target_os = "linux",
target_os = "netbsd",
target_os = "l4re"
))]
unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
let mut ret = None;
let mut attr: libc::pthread_attr_t = crate::mem::zeroed();
#[cfg(target_os = "freebsd")]
assert_eq!(libc::pthread_attr_init(&mut attr), 0);
#[cfg(target_os = "freebsd")]
let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr);
#[cfg(not(target_os = "freebsd"))]
let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr);
if e == 0 {
let mut stackaddr = crate::ptr::null_mut();
let mut stacksize = 0;
assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr, &mut stacksize), 0);
ret = Some(stackaddr);
}
if e == 0 || cfg!(target_os = "freebsd") {
assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
}
ret
}
// Precondition: PAGE_SIZE is initialized.
unsafe fn get_stack_start_aligned() -> Option<*mut libc::c_void> {
let page_size = PAGE_SIZE.load(Ordering::Relaxed);
assert!(page_size != 0);
let stackaddr = get_stack_start()?;
// Ensure stackaddr is page aligned! A parent process might
// have reset RLIMIT_STACK to be non-page aligned. The
// pthread_attr_getstack() reports the usable stack area
// stackaddr < stackaddr + stacksize, so if stackaddr is not
// page-aligned, calculate the fix such that stackaddr <
// new_page_aligned_stackaddr < stackaddr + stacksize
let remainder = (stackaddr as usize) % page_size;
Some(if remainder == 0 {
stackaddr
} else {
((stackaddr as usize) + page_size - remainder) as *mut libc::c_void
})
}
pub unsafe fn init() -> Option<Guard> {
let page_size = os::page_size();
PAGE_SIZE.store(page_size, Ordering::Relaxed);
if cfg!(all(target_os = "linux", not(target_env = "musl"))) {
// Linux doesn't allocate the whole stack right away, and
// the kernel has its own stack-guard mechanism to fault
// when growing too close to an existing mapping. If we map
// our own guard, then the kernel starts enforcing a rather
// large gap above that, rendering much of the possible
// stack space useless. See #43052.
//
// Instead, we'll just note where we expect rlimit to start
// faulting, so our handler can report "stack overflow", and
// trust that the kernel's own stack guard will work.
let stackaddr = get_stack_start_aligned()?;
let stackaddr = stackaddr as usize;
Some(stackaddr - page_size..stackaddr)
} else if cfg!(all(target_os = "linux", target_env = "musl")) {
// For the main thread, the musl's pthread_attr_getstack
// returns the current stack size, rather than maximum size
// it can eventually grow to. It cannot be used to determine
// the position of kernel's stack guard.
None
} else if cfg!(target_os = "freebsd") {
// FreeBSD's stack autogrows, and optionally includes a guard page
// at the bottom. If we try to remap the bottom of the stack
// ourselves, FreeBSD's guard page moves upwards. So we'll just use
// the builtin guard page.
let stackaddr = get_stack_start_aligned()?;
let guardaddr = stackaddr as usize;
// Technically the number of guard pages is tunable and controlled
// by the security.bsd.stack_guard_page sysctl, but there are
// few reasons to change it from the default. The default value has
// been 1 ever since FreeBSD 11.1 and 10.4.
const GUARD_PAGES: usize = 1;
let guard = guardaddr..guardaddr + GUARD_PAGES * page_size;
Some(guard)
} else {
// Reallocate the last page of the stack.
// This ensures SIGBUS will be raised on
// stack overflow.
// Systems which enforce strict PAX MPROTECT do not allow
// to mprotect() a mapping with less restrictive permissions
// than the initial mmap() used, so we mmap() here with
// read/write permissions and only then mprotect() it to
// no permissions at all. See issue #50313.
let stackaddr = get_stack_start_aligned()?;
let result = mmap(
stackaddr,
page_size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON | MAP_FIXED,
-1,
0,
);
if result != stackaddr || result == MAP_FAILED {
panic!("failed to allocate a guard page: {}", io::Error::last_os_error());
}
let result = mprotect(stackaddr, page_size, PROT_NONE);
if result != 0 {
panic!("failed to protect the guard page: {}", io::Error::last_os_error());
}
let guardaddr = stackaddr as usize;
Some(guardaddr..guardaddr + page_size)
}
}
#[cfg(any(target_os = "macos", target_os = "openbsd", target_os = "solaris"))]
pub unsafe fn current() -> Option<Guard> {
let stackaddr = get_stack_start()? as usize;
Some(stackaddr - PAGE_SIZE.load(Ordering::Relaxed)..stackaddr)
}
#[cfg(any(
target_os = "android",
target_os = "freebsd",
target_os = "linux",
target_os = "netbsd",
target_os = "l4re"
))]
pub unsafe fn current() -> Option<Guard> {
let mut ret = None;
let mut attr: libc::pthread_attr_t = crate::mem::zeroed();
#[cfg(target_os = "freebsd")]
assert_eq!(libc::pthread_attr_init(&mut attr), 0);
#[cfg(target_os = "freebsd")]
let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr);
#[cfg(not(target_os = "freebsd"))]
let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr);
if e == 0 {
let mut guardsize = 0;
assert_eq!(libc::pthread_attr_getguardsize(&attr, &mut guardsize), 0);
if guardsize == 0 {
if cfg!(all(target_os = "linux", target_env = "musl")) {
// musl versions before 1.1.19 always reported guard
// size obtained from pthread_attr_get_np as zero.
// Use page size as a fallback.
guardsize = PAGE_SIZE.load(Ordering::Relaxed);
} else {
panic!("there is no guard page");
}
}
let mut stackaddr = crate::ptr::null_mut();
let mut size = 0;
assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr, &mut size), 0);
let stackaddr = stackaddr as usize;
ret = if cfg!(any(target_os = "freebsd", target_os = "netbsd")) {
Some(stackaddr - guardsize..stackaddr)
} else if cfg!(all(target_os = "linux", target_env = "musl")) {
Some(stackaddr - guardsize..stackaddr)
} else if cfg!(all(target_os = "linux", any(target_env = "gnu", target_env = "uclibc")))
{
// glibc used to include the guard area within the stack, as noted in the BUGS
// section of `man pthread_attr_getguardsize`. This has been corrected starting
// with glibc 2.27, and in some distro backports, so the guard is now placed at the
// end (below) the stack. There's no easy way for us to know which we have at
// runtime, so we'll just match any fault in the range right above or below the
// stack base to call that fault a stack overflow.
Some(stackaddr - guardsize..stackaddr + guardsize)
} else {
Some(stackaddr..stackaddr + guardsize)
};
}
if e == 0 || cfg!(target_os = "freebsd") {
assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
}
ret
}
}
// glibc >= 2.15 has a __pthread_get_minstack() function that returns
// PTHREAD_STACK_MIN plus bytes needed for thread-local storage.
// We need that information to avoid blowing up when a small stack
// is created in an application with big thread-local storage requirements.
// See #6233 for rationale and details.
#[cfg(all(target_os = "linux", target_env = "gnu"))]
fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
// We use dlsym to avoid an ELF version dependency on GLIBC_PRIVATE. (#23628)
// We shouldn't really be using such an internal symbol, but there's currently
// no other way to account for the TLS size.
dlsym!(fn __pthread_get_minstack(*const libc::pthread_attr_t) -> libc::size_t);
match __pthread_get_minstack.get() {
None => libc::PTHREAD_STACK_MIN,
Some(f) => unsafe { f(attr) },
}
}
// No point in looking up __pthread_get_minstack() on non-glibc platforms.
#[cfg(all(not(all(target_os = "linux", target_env = "gnu")), not(target_os = "netbsd")))]
fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
libc::PTHREAD_STACK_MIN
}
#[cfg(target_os = "netbsd")]
fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
2048 // just a guess
}