diff options
Diffstat (limited to 'library/std/src/sys/wasi/thread.rs')
| -rw-r--r-- | library/std/src/sys/wasi/thread.rs | 132 |
1 files changed, 126 insertions, 6 deletions
diff --git a/library/std/src/sys/wasi/thread.rs b/library/std/src/sys/wasi/thread.rs index e7a6ab4be82..a0eefa8811a 100644 --- a/library/std/src/sys/wasi/thread.rs +++ b/library/std/src/sys/wasi/thread.rs @@ -1,5 +1,3 @@ -#![deny(unsafe_op_in_unsafe_fn)] - use crate::ffi::CStr; use crate::io; use crate::mem; @@ -7,14 +5,124 @@ use crate::num::NonZeroUsize; use crate::sys::unsupported; use crate::time::Duration; -pub struct Thread(!); +cfg_if::cfg_if! { + if #[cfg(target_feature = "atomics")] { + use crate::cmp; + use crate::ptr; + use crate::sys::os; + // Add a few symbols not in upstream `libc` just yet. + mod libc { + pub use crate::ffi; + pub use crate::mem; + pub use libc::*; + + // defined in wasi-libc + // https://github.com/WebAssembly/wasi-libc/blob/a6f871343313220b76009827ed0153586361c0d5/libc-top-half/musl/include/alltypes.h.in#L108 + #[repr(C)] + union pthread_attr_union { + __i: [ffi::c_int; if mem::size_of::<ffi::c_long>() == 8 { 14 } else { 9 }], + __vi: [ffi::c_int; if mem::size_of::<ffi::c_long>() == 8 { 14 } else { 9 }], + __s: [ffi::c_ulong; if mem::size_of::<ffi::c_long>() == 8 { 7 } else { 9 }], + } + + #[repr(C)] + pub struct pthread_attr_t { + __u: pthread_attr_union, + } + + #[allow(non_camel_case_types)] + pub type pthread_t = *mut ffi::c_void; + + extern "C" { + pub fn pthread_create( + native: *mut pthread_t, + attr: *const pthread_attr_t, + f: extern "C" fn(*mut ffi::c_void) -> *mut ffi::c_void, + value: *mut ffi::c_void, + ) -> ffi::c_int; + pub fn pthread_join(native: pthread_t, value: *mut *mut ffi::c_void) -> ffi::c_int; + pub fn pthread_attr_init(attrp: *mut pthread_attr_t) -> ffi::c_int; + pub fn pthread_attr_setstacksize( + attr: *mut pthread_attr_t, + stack_size: libc::size_t, + ) -> ffi::c_int; + pub fn pthread_attr_destroy(attr: *mut pthread_attr_t) -> ffi::c_int; + pub fn pthread_detach(thread: pthread_t) -> ffi::c_int; + } + } + + pub struct Thread { + id: libc::pthread_t, + } + + impl Drop for Thread { + fn drop(&mut self) { + let ret = unsafe { libc::pthread_detach(self.id) }; + debug_assert_eq!(ret, 0); + } + } + } else { + pub struct Thread(!); + } +} pub const DEFAULT_MIN_STACK_SIZE: usize = 4096; impl Thread { // unsafe: see thread::Builder::spawn_unchecked for safety requirements - pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> { - unsupported() + cfg_if::cfg_if! { + if #[cfg(target_feature = "atomics")] { + pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> { + let p = Box::into_raw(Box::new(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, DEFAULT_MIN_STACK_SIZE); + + 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 { + // Finally, let's run some code. + Box::from_raw(main as *mut Box<dyn FnOnce()>)(); + } + ptr::null_mut() + } + } + } else { + pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> { + unsupported() + } + } } pub fn yield_now() { @@ -62,7 +170,19 @@ impl Thread { } pub fn join(self) { - self.0 + cfg_if::cfg_if! { + if #[cfg(target_feature = "atomics")] { + unsafe { + let ret = libc::pthread_join(self.id, ptr::null_mut()); + mem::forget(self); + if ret != 0 { + rtabort!("failed to join thread: {}", io::Error::from_raw_os_error(ret)); + } + } + } else { + self.0 + } + } } } |