diff options
Diffstat (limited to 'library/std/src/sys/pal/unix/stack_overflow.rs')
| -rw-r--r-- | library/std/src/sys/pal/unix/stack_overflow.rs | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/library/std/src/sys/pal/unix/stack_overflow.rs b/library/std/src/sys/pal/unix/stack_overflow.rs index 0886624160c..160e58e16a5 100644 --- a/library/std/src/sys/pal/unix/stack_overflow.rs +++ b/library/std/src/sys/pal/unix/stack_overflow.rs @@ -123,28 +123,36 @@ mod imp { static MAIN_ALTSTACK: AtomicPtr<libc::c_void> = AtomicPtr::new(ptr::null_mut()); static NEED_ALTSTACK: AtomicBool = AtomicBool::new(false); + /// # Safety + /// Must be called only once + #[forbid(unsafe_op_in_unsafe_fn)] pub unsafe fn init() { PAGE_SIZE.store(os::page_size(), Ordering::Relaxed); // Always write to GUARD to ensure the TLS variable is allocated. - let guard = install_main_guard().unwrap_or(0..0); + let guard = unsafe { install_main_guard().unwrap_or(0..0) }; GUARD.set((guard.start, guard.end)); - let mut action: sigaction = mem::zeroed(); + // SAFETY: assuming all platforms define struct sigaction as "zero-initializable" + let mut action: sigaction = unsafe { mem::zeroed() }; for &signal in &[SIGSEGV, SIGBUS] { - sigaction(signal, ptr::null_mut(), &mut action); + // SAFETY: just fetches the current signal handler into action + unsafe { sigaction(signal, ptr::null_mut(), &mut action) }; // Configure our signal handler if one is not already set. if action.sa_sigaction == SIG_DFL { + if !NEED_ALTSTACK.load(Ordering::Relaxed) { + // haven't set up our sigaltstack yet + NEED_ALTSTACK.store(true, Ordering::Release); + let handler = unsafe { make_handler(true) }; + MAIN_ALTSTACK.store(handler.data, Ordering::Relaxed); + mem::forget(handler); + } action.sa_flags = SA_SIGINFO | SA_ONSTACK; action.sa_sigaction = signal_handler as sighandler_t; - sigaction(signal, &action, ptr::null_mut()); - NEED_ALTSTACK.store(true, Ordering::Relaxed); + // SAFETY: only overriding signals if the default is set + unsafe { sigaction(signal, &action, ptr::null_mut()) }; } } - - let handler = make_handler(true); - MAIN_ALTSTACK.store(handler.data, Ordering::Relaxed); - mem::forget(handler); } pub unsafe fn cleanup() { |