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use crate::cmp;
use crate::ffi::CStr;
use crate::io;
use crate::mem;
use crate::ptr;
use crate::sys::{os, stack_overflow};
use crate::time::Duration;
#[cfg(not(target_os = "l4re"))]
pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
#[cfg(target_os = "l4re")]
pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
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 {}
// The pthread_attr_setstacksize symbol doesn't exist in the emscripten libc,
// so we have to not link to it to satisfy emcc's ERROR_ON_UNDEFINED_SYMBOLS.
#[cfg(not(target_os = "emscripten"))]
unsafe fn pthread_attr_setstacksize(
attr: *mut libc::pthread_attr_t,
stack_size: libc::size_t,
) -> libc::c_int {
libc::pthread_attr_setstacksize(attr, stack_size)
}
#[cfg(target_os = "emscripten")]
unsafe fn pthread_attr_setstacksize(
_attr: *mut libc::pthread_attr_t,
_stack_size: libc::size_t,
) -> libc::c_int {
panic!()
}
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);
let stack_size = cmp::max(stack, min_stack_size(&attr));
match 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(any(
target_env = "newlib",
target_os = "haiku",
target_os = "l4re",
target_os = "emscripten",
target_os = "redox"
))]
pub fn set_name(_name: &CStr) {
// Newlib, Haiku, and Emscripten have no way to set a thread name.
}
#[cfg(target_os = "fuchsia")]
pub fn set_name(_name: &CStr) {
// FIXME: determine whether Fuchsia has a way to set a thread name.
}
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_value() as u64, secs) as libc::time_t,
tv_nsec: nsecs,
};
secs -= ts.tv_sec as u64;
if libc::nanosleep(&ts, &mut ts) == -1 {
assert_eq!(os::errno(), libc::EINTR);
secs += ts.tv_sec as u64;
nsecs = ts.tv_nsec;
} else {
nsecs = 0;
}
}
}
}
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);
}
}
#[cfg(all(
not(all(target_os = "linux", not(target_env = "musl"))),
not(target_os = "freebsd"),
not(target_os = "macos"),
not(all(target_os = "netbsd", not(target_vendor = "rumprun"))),
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(
all(target_os = "linux", not(target_env = "musl")),
target_os = "freebsd",
target_os = "macos",
all(target_os = "netbsd", not(target_vendor = "rumprun")),
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::ops::Range;
use crate::sys::os;
// This is initialized in init() and only read from after
static mut PAGE_SIZE: usize = 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
} 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();
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);
}
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> {
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> {
PAGE_SIZE = os::page_size();
let stackaddr = get_stack_start_aligned()?;
if cfg!(target_os = "linux") {
// 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 = stackaddr as usize;
Some(stackaddr - PAGE_SIZE..stackaddr)
} 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 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");
}
let result = mprotect(stackaddr, PAGE_SIZE, PROT_NONE);
if result != 0 {
panic!("failed to protect the guard page");
}
let guardaddr = stackaddr as usize;
let offset = if cfg!(target_os = "freebsd") { 2 } else { 1 };
Some(guardaddr..guardaddr + offset * 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..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();
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 {
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!(target_os = "freebsd") {
// FIXME does freebsd really fault *below* the guard addr?
let guardaddr = stackaddr - guardsize;
Some(guardaddr - PAGE_SIZE..guardaddr)
} else if cfg!(target_os = "netbsd") {
Some(stackaddr - guardsize..stackaddr)
} else if cfg!(all(target_os = "linux", target_env = "gnu")) {
// 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)
};
}
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(target_os = "linux")]
#[allow(deprecated)]
fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
weak!(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(target_os = "linux"), 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
}