mirror of https://github.com/rust-lang/rust
858 lines
30 KiB
Rust
858 lines
30 KiB
Rust
//! Implementation of various bits and pieces of the `panic!` macro and
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//! associated runtime pieces.
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//!
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//! Specifically, this module contains the implementation of:
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//!
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//! * Panic hooks
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//! * Executing a panic up to doing the actual implementation
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//! * Shims around "try"
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#![deny(unsafe_op_in_unsafe_fn)]
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use crate::panic::BacktraceStyle;
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use core::panic::{Location, PanicInfo, PanicPayload};
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use crate::any::Any;
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use crate::fmt;
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use crate::intrinsics;
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use crate::mem::{self, ManuallyDrop};
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use crate::process;
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use crate::sync::atomic::{AtomicBool, Ordering};
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use crate::sync::{PoisonError, RwLock};
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use crate::sys::stdio::panic_output;
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use crate::sys_common::backtrace;
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use crate::thread;
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#[cfg(not(test))]
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use crate::io::try_set_output_capture;
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// make sure to use the stderr output configured
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// by libtest in the real copy of std
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#[cfg(test)]
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use realstd::io::try_set_output_capture;
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// Binary interface to the panic runtime that the standard library depends on.
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//
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// The standard library is tagged with `#![needs_panic_runtime]` (introduced in
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// RFC 1513) to indicate that it requires some other crate tagged with
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// `#![panic_runtime]` to exist somewhere. Each panic runtime is intended to
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// implement these symbols (with the same signatures) so we can get matched up
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// to them.
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//
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// One day this may look a little less ad-hoc with the compiler helping out to
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// hook up these functions, but it is not this day!
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#[allow(improper_ctypes)]
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extern "C" {
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fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static);
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}
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extern "Rust" {
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/// `PanicPayload` lazily performs allocation only when needed (this avoids
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/// allocations when using the "abort" panic runtime).
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fn __rust_start_panic(payload: &mut dyn PanicPayload) -> u32;
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}
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/// This function is called by the panic runtime if FFI code catches a Rust
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/// panic but doesn't rethrow it. We don't support this case since it messes
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/// with our panic count.
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#[cfg(not(test))]
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#[rustc_std_internal_symbol]
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extern "C" fn __rust_drop_panic() -> ! {
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rtabort!("Rust panics must be rethrown");
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}
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/// This function is called by the panic runtime if it catches an exception
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/// object which does not correspond to a Rust panic.
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#[cfg(not(test))]
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#[rustc_std_internal_symbol]
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extern "C" fn __rust_foreign_exception() -> ! {
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rtabort!("Rust cannot catch foreign exceptions");
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}
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enum Hook {
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Default,
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Custom(Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>),
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}
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impl Hook {
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#[inline]
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fn into_box(self) -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send> {
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match self {
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Hook::Default => Box::new(default_hook),
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Hook::Custom(hook) => hook,
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}
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}
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}
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impl Default for Hook {
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#[inline]
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fn default() -> Hook {
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Hook::Default
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}
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}
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static HOOK: RwLock<Hook> = RwLock::new(Hook::Default);
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/// Registers a custom panic hook, replacing the previously registered hook.
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///
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/// The panic hook is invoked when a thread panics, but before the panic runtime
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/// is invoked. As such, the hook will run with both the aborting and unwinding
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/// runtimes.
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///
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/// The default hook, which is registered at startup, prints a message to standard error and
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/// generates a backtrace if requested. This behavior can be customized using the `set_hook` function.
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/// The current hook can be retrieved while reinstating the default hook with the [`take_hook`]
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/// function.
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///
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/// [`take_hook`]: ./fn.take_hook.html
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///
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/// The hook is provided with a `PanicInfo` struct which contains information
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/// about the origin of the panic, including the payload passed to `panic!` and
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/// the source code location from which the panic originated.
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///
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/// The panic hook is a global resource.
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///
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/// # Panics
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///
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/// Panics if called from a panicking thread.
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///
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/// # Examples
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///
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/// The following will print "Custom panic hook":
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///
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/// ```should_panic
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/// use std::panic;
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///
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/// panic::set_hook(Box::new(|_| {
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/// println!("Custom panic hook");
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/// }));
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///
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/// panic!("Normal panic");
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/// ```
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#[stable(feature = "panic_hooks", since = "1.10.0")]
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pub fn set_hook(hook: Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>) {
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if thread::panicking() {
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panic!("cannot modify the panic hook from a panicking thread");
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}
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let new = Hook::Custom(hook);
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let mut hook = HOOK.write().unwrap_or_else(PoisonError::into_inner);
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let old = mem::replace(&mut *hook, new);
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drop(hook);
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// Only drop the old hook after releasing the lock to avoid deadlocking
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// if its destructor panics.
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drop(old);
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}
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/// Unregisters the current panic hook and returns it, registering the default hook
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/// in its place.
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///
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/// *See also the function [`set_hook`].*
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///
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/// [`set_hook`]: ./fn.set_hook.html
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///
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/// If the default hook is registered it will be returned, but remain registered.
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///
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/// # Panics
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///
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/// Panics if called from a panicking thread.
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///
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/// # Examples
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///
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/// The following will print "Normal panic":
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///
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/// ```should_panic
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/// use std::panic;
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///
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/// panic::set_hook(Box::new(|_| {
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/// println!("Custom panic hook");
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/// }));
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///
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/// let _ = panic::take_hook();
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///
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/// panic!("Normal panic");
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/// ```
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#[must_use]
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#[stable(feature = "panic_hooks", since = "1.10.0")]
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pub fn take_hook() -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send> {
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if thread::panicking() {
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panic!("cannot modify the panic hook from a panicking thread");
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}
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let mut hook = HOOK.write().unwrap_or_else(PoisonError::into_inner);
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let old_hook = mem::take(&mut *hook);
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drop(hook);
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old_hook.into_box()
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}
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/// Atomic combination of [`take_hook`] and [`set_hook`]. Use this to replace the panic handler with
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/// a new panic handler that does something and then executes the old handler.
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///
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/// [`take_hook`]: ./fn.take_hook.html
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/// [`set_hook`]: ./fn.set_hook.html
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///
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/// # Panics
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///
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/// Panics if called from a panicking thread.
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///
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/// # Examples
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///
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/// The following will print the custom message, and then the normal output of panic.
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///
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/// ```should_panic
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/// #![feature(panic_update_hook)]
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/// use std::panic;
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///
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/// // Equivalent to
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/// // let prev = panic::take_hook();
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/// // panic::set_hook(move |info| {
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/// // println!("...");
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/// // prev(info);
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/// // );
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/// panic::update_hook(move |prev, info| {
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/// println!("Print custom message and execute panic handler as usual");
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/// prev(info);
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/// });
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///
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/// panic!("Custom and then normal");
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/// ```
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#[unstable(feature = "panic_update_hook", issue = "92649")]
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pub fn update_hook<F>(hook_fn: F)
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where
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F: Fn(&(dyn Fn(&PanicInfo<'_>) + Send + Sync + 'static), &PanicInfo<'_>)
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+ Sync
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+ Send
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+ 'static,
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{
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if thread::panicking() {
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panic!("cannot modify the panic hook from a panicking thread");
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}
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let mut hook = HOOK.write().unwrap_or_else(PoisonError::into_inner);
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let prev = mem::take(&mut *hook).into_box();
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*hook = Hook::Custom(Box::new(move |info| hook_fn(&prev, info)));
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}
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/// The default panic handler.
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fn default_hook(info: &PanicInfo<'_>) {
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// If this is a double panic, make sure that we print a backtrace
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// for this panic. Otherwise only print it if logging is enabled.
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let backtrace = if info.force_no_backtrace() {
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None
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} else if panic_count::get_count() >= 2 {
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BacktraceStyle::full()
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} else {
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crate::panic::get_backtrace_style()
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};
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// The current implementation always returns `Some`.
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let location = info.location().unwrap();
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let msg = match info.payload().downcast_ref::<&'static str>() {
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Some(s) => *s,
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None => match info.payload().downcast_ref::<String>() {
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Some(s) => &s[..],
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None => "Box<dyn Any>",
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},
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};
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let thread = thread::try_current();
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let name = thread.as_ref().and_then(|t| t.name()).unwrap_or("<unnamed>");
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let write = |err: &mut dyn crate::io::Write| {
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let _ = writeln!(err, "thread '{name}' panicked at {location}:\n{msg}");
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static FIRST_PANIC: AtomicBool = AtomicBool::new(true);
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match backtrace {
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Some(BacktraceStyle::Short) => {
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drop(backtrace::print(err, crate::backtrace_rs::PrintFmt::Short))
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}
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Some(BacktraceStyle::Full) => {
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drop(backtrace::print(err, crate::backtrace_rs::PrintFmt::Full))
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}
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Some(BacktraceStyle::Off) => {
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if FIRST_PANIC.swap(false, Ordering::Relaxed) {
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let _ = writeln!(
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err,
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"note: run with `RUST_BACKTRACE=1` environment variable to display a \
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backtrace"
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);
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if cfg!(miri) {
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let _ = writeln!(
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err,
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"note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` \
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for the environment variable to have an effect"
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);
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}
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}
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}
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// If backtraces aren't supported or are forced-off, do nothing.
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None => {}
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}
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};
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if let Ok(Some(local)) = try_set_output_capture(None) {
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write(&mut *local.lock().unwrap_or_else(|e| e.into_inner()));
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try_set_output_capture(Some(local)).ok();
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} else if let Some(mut out) = panic_output() {
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write(&mut out);
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}
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}
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#[cfg(not(test))]
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#[doc(hidden)]
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#[cfg(feature = "panic_immediate_abort")]
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#[unstable(feature = "update_panic_count", issue = "none")]
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pub mod panic_count {
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/// A reason for forcing an immediate abort on panic.
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#[derive(Debug)]
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pub enum MustAbort {
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AlwaysAbort,
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PanicInHook,
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}
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#[inline]
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pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
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None
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}
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#[inline]
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pub fn finished_panic_hook() {}
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#[inline]
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pub fn decrease() {}
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#[inline]
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pub fn set_always_abort() {}
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// Disregards ALWAYS_ABORT_FLAG
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#[inline]
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#[must_use]
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pub fn get_count() -> usize {
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0
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}
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#[must_use]
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#[inline]
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pub fn count_is_zero() -> bool {
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true
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}
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}
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#[cfg(not(test))]
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#[doc(hidden)]
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#[cfg(not(feature = "panic_immediate_abort"))]
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#[unstable(feature = "update_panic_count", issue = "none")]
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pub mod panic_count {
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use crate::cell::Cell;
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use crate::sync::atomic::{AtomicUsize, Ordering};
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const ALWAYS_ABORT_FLAG: usize = 1 << (usize::BITS - 1);
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/// A reason for forcing an immediate abort on panic.
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#[derive(Debug)]
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pub enum MustAbort {
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AlwaysAbort,
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PanicInHook,
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}
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// Panic count for the current thread and whether a panic hook is currently
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// being executed..
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thread_local! {
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static LOCAL_PANIC_COUNT: Cell<(usize, bool)> = const { Cell::new((0, false)) }
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}
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// Sum of panic counts from all threads. The purpose of this is to have
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// a fast path in `count_is_zero` (which is used by `panicking`). In any particular
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// thread, if that thread currently views `GLOBAL_PANIC_COUNT` as being zero,
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// then `LOCAL_PANIC_COUNT` in that thread is zero. This invariant holds before
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// and after increase and decrease, but not necessarily during their execution.
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//
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// Additionally, the top bit of GLOBAL_PANIC_COUNT (GLOBAL_ALWAYS_ABORT_FLAG)
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// records whether panic::always_abort() has been called. This can only be
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// set, never cleared.
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// panic::always_abort() is usually called to prevent memory allocations done by
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// the panic handling in the child created by `libc::fork`.
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// Memory allocations performed in a child created with `libc::fork` are undefined
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// behavior in most operating systems.
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// Accessing LOCAL_PANIC_COUNT in a child created by `libc::fork` would lead to a memory
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// allocation. Only GLOBAL_PANIC_COUNT can be accessed in this situation. This is
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// sufficient because a child process will always have exactly one thread only.
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// See also #85261 for details.
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//
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// This could be viewed as a struct containing a single bit and an n-1-bit
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// value, but if we wrote it like that it would be more than a single word,
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// and even a newtype around usize would be clumsy because we need atomics.
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// But we use such a tuple for the return type of increase().
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//
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// Stealing a bit is fine because it just amounts to assuming that each
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// panicking thread consumes at least 2 bytes of address space.
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static GLOBAL_PANIC_COUNT: AtomicUsize = AtomicUsize::new(0);
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// Increases the global and local panic count, and returns whether an
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// immediate abort is required.
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//
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// This also updates thread-local state to keep track of whether a panic
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// hook is currently executing.
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pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
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let global_count = GLOBAL_PANIC_COUNT.fetch_add(1, Ordering::Relaxed);
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if global_count & ALWAYS_ABORT_FLAG != 0 {
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// Do *not* access thread-local state, we might be after a `fork`.
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return Some(MustAbort::AlwaysAbort);
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}
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LOCAL_PANIC_COUNT.with(|c| {
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let (count, in_panic_hook) = c.get();
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if in_panic_hook {
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return Some(MustAbort::PanicInHook);
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}
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c.set((count + 1, run_panic_hook));
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None
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})
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}
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pub fn finished_panic_hook() {
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LOCAL_PANIC_COUNT.with(|c| {
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let (count, _) = c.get();
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c.set((count, false));
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});
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}
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pub fn decrease() {
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GLOBAL_PANIC_COUNT.fetch_sub(1, Ordering::Relaxed);
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LOCAL_PANIC_COUNT.with(|c| {
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let (count, _) = c.get();
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c.set((count - 1, false));
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});
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}
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pub fn set_always_abort() {
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GLOBAL_PANIC_COUNT.fetch_or(ALWAYS_ABORT_FLAG, Ordering::Relaxed);
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}
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// Disregards ALWAYS_ABORT_FLAG
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#[must_use]
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pub fn get_count() -> usize {
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LOCAL_PANIC_COUNT.with(|c| c.get().0)
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}
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// Disregards ALWAYS_ABORT_FLAG
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#[must_use]
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#[inline]
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pub fn count_is_zero() -> bool {
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if GLOBAL_PANIC_COUNT.load(Ordering::Relaxed) & !ALWAYS_ABORT_FLAG == 0 {
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// Fast path: if `GLOBAL_PANIC_COUNT` is zero, all threads
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// (including the current one) will have `LOCAL_PANIC_COUNT`
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// equal to zero, so TLS access can be avoided.
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//
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// In terms of performance, a relaxed atomic load is similar to a normal
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// aligned memory read (e.g., a mov instruction in x86), but with some
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// compiler optimization restrictions. On the other hand, a TLS access
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// might require calling a non-inlinable function (such as `__tls_get_addr`
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// when using the GD TLS model).
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true
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} else {
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is_zero_slow_path()
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}
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}
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// Slow path is in a separate function to reduce the amount of code
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// inlined from `count_is_zero`.
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#[inline(never)]
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#[cold]
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fn is_zero_slow_path() -> bool {
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LOCAL_PANIC_COUNT.with(|c| c.get().0 == 0)
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}
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}
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#[cfg(test)]
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pub use realstd::rt::panic_count;
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/// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
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#[cfg(feature = "panic_immediate_abort")]
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pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
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Ok(f())
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}
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/// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
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#[cfg(not(feature = "panic_immediate_abort"))]
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pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
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union Data<F, R> {
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f: ManuallyDrop<F>,
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r: ManuallyDrop<R>,
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p: ManuallyDrop<Box<dyn Any + Send>>,
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}
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// We do some sketchy operations with ownership here for the sake of
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// performance. We can only pass pointers down to `do_call` (can't pass
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// objects by value), so we do all the ownership tracking here manually
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// using a union.
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//
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// We go through a transition where:
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//
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// * First, we set the data field `f` to be the argumentless closure that we're going to call.
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// * When we make the function call, the `do_call` function below, we take
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// ownership of the function pointer. At this point the `data` union is
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// entirely uninitialized.
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// * If the closure successfully returns, we write the return value into the
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|
// data's return slot (field `r`).
|
|
// * If the closure panics (`do_catch` below), we write the panic payload into field `p`.
|
|
// * Finally, when we come back out of the `try` intrinsic we're
|
|
// in one of two states:
|
|
//
|
|
// 1. The closure didn't panic, in which case the return value was
|
|
// filled in. We move it out of `data.r` and return it.
|
|
// 2. The closure panicked, in which case the panic payload was
|
|
// filled in. We move it out of `data.p` and return it.
|
|
//
|
|
// Once we stack all that together we should have the "most efficient'
|
|
// method of calling a catch panic whilst juggling ownership.
|
|
let mut data = Data { f: ManuallyDrop::new(f) };
|
|
|
|
let data_ptr = core::ptr::addr_of_mut!(data) as *mut u8;
|
|
// SAFETY:
|
|
//
|
|
// Access to the union's fields: this is `std` and we know that the `r#try`
|
|
// intrinsic fills in the `r` or `p` union field based on its return value.
|
|
//
|
|
// The call to `intrinsics::catch_unwind` is made safe by:
|
|
// - `do_call`, the first argument, can be called with the initial `data_ptr`.
|
|
// - `do_catch`, the second argument, can be called with the `data_ptr` as well.
|
|
// See their safety preconditions for more information
|
|
unsafe {
|
|
return if intrinsics::catch_unwind(do_call::<F, R>, data_ptr, do_catch::<F, R>) == 0 {
|
|
Ok(ManuallyDrop::into_inner(data.r))
|
|
} else {
|
|
Err(ManuallyDrop::into_inner(data.p))
|
|
};
|
|
}
|
|
|
|
// We consider unwinding to be rare, so mark this function as cold. However,
|
|
// do not mark it no-inline -- that decision is best to leave to the
|
|
// optimizer (in most cases this function is not inlined even as a normal,
|
|
// non-cold function, though, as of the writing of this comment).
|
|
#[cold]
|
|
unsafe fn cleanup(payload: *mut u8) -> Box<dyn Any + Send + 'static> {
|
|
// SAFETY: The whole unsafe block hinges on a correct implementation of
|
|
// the panic handler `__rust_panic_cleanup`. As such we can only
|
|
// assume it returns the correct thing for `Box::from_raw` to work
|
|
// without undefined behavior.
|
|
let obj = unsafe { Box::from_raw(__rust_panic_cleanup(payload)) };
|
|
panic_count::decrease();
|
|
obj
|
|
}
|
|
|
|
// SAFETY:
|
|
// data must be non-NUL, correctly aligned, and a pointer to a `Data<F, R>`
|
|
// Its must contains a valid `f` (type: F) value that can be use to fill
|
|
// `data.r`.
|
|
//
|
|
// This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
|
|
// expects normal function pointers.
|
|
#[inline]
|
|
fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
|
|
// SAFETY: this is the responsibility of the caller, see above.
|
|
unsafe {
|
|
let data = data as *mut Data<F, R>;
|
|
let data = &mut (*data);
|
|
let f = ManuallyDrop::take(&mut data.f);
|
|
data.r = ManuallyDrop::new(f());
|
|
}
|
|
}
|
|
|
|
// We *do* want this part of the catch to be inlined: this allows the
|
|
// compiler to properly track accesses to the Data union and optimize it
|
|
// away most of the time.
|
|
//
|
|
// SAFETY:
|
|
// data must be non-NUL, correctly aligned, and a pointer to a `Data<F, R>`
|
|
// Since this uses `cleanup` it also hinges on a correct implementation of
|
|
// `__rustc_panic_cleanup`.
|
|
//
|
|
// This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
|
|
// expects normal function pointers.
|
|
#[inline]
|
|
#[rustc_nounwind] // `intrinsic::r#try` requires catch fn to be nounwind
|
|
fn do_catch<F: FnOnce() -> R, R>(data: *mut u8, payload: *mut u8) {
|
|
// SAFETY: this is the responsibility of the caller, see above.
|
|
//
|
|
// When `__rustc_panic_cleaner` is correctly implemented we can rely
|
|
// on `obj` being the correct thing to pass to `data.p` (after wrapping
|
|
// in `ManuallyDrop`).
|
|
unsafe {
|
|
let data = data as *mut Data<F, R>;
|
|
let data = &mut (*data);
|
|
let obj = cleanup(payload);
|
|
data.p = ManuallyDrop::new(obj);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Determines whether the current thread is unwinding because of panic.
|
|
#[inline]
|
|
pub fn panicking() -> bool {
|
|
!panic_count::count_is_zero()
|
|
}
|
|
|
|
/// Entry point of panics from the core crate (`panic_impl` lang item).
|
|
#[cfg(not(any(test, doctest)))]
|
|
#[panic_handler]
|
|
pub fn begin_panic_handler(info: &PanicInfo<'_>) -> ! {
|
|
struct FormatStringPayload<'a> {
|
|
inner: &'a fmt::Arguments<'a>,
|
|
string: Option<String>,
|
|
}
|
|
|
|
impl<'a> FormatStringPayload<'a> {
|
|
fn new(inner: &'a fmt::Arguments<'a>) -> Self {
|
|
Self { inner, string: None }
|
|
}
|
|
|
|
fn fill(&mut self) -> &mut String {
|
|
use crate::fmt::Write;
|
|
|
|
let inner = self.inner;
|
|
// Lazily, the first time this gets called, run the actual string formatting.
|
|
self.string.get_or_insert_with(|| {
|
|
let mut s = String::new();
|
|
let _err = s.write_fmt(*inner);
|
|
s
|
|
})
|
|
}
|
|
}
|
|
|
|
unsafe impl<'a> PanicPayload for FormatStringPayload<'a> {
|
|
fn take_box(&mut self) -> *mut (dyn Any + Send) {
|
|
// We do two allocations here, unfortunately. But (a) they're required with the current
|
|
// scheme, and (b) we don't handle panic + OOM properly anyway (see comment in
|
|
// begin_panic below).
|
|
let contents = mem::take(self.fill());
|
|
Box::into_raw(Box::new(contents))
|
|
}
|
|
|
|
fn get(&mut self) -> &(dyn Any + Send) {
|
|
self.fill()
|
|
}
|
|
}
|
|
|
|
struct StaticStrPayload(&'static str);
|
|
|
|
unsafe impl PanicPayload for StaticStrPayload {
|
|
fn take_box(&mut self) -> *mut (dyn Any + Send) {
|
|
Box::into_raw(Box::new(self.0))
|
|
}
|
|
|
|
fn get(&mut self) -> &(dyn Any + Send) {
|
|
&self.0
|
|
}
|
|
}
|
|
|
|
let loc = info.location().unwrap(); // The current implementation always returns Some
|
|
let msg = info.message().unwrap(); // The current implementation always returns Some
|
|
crate::sys_common::backtrace::__rust_end_short_backtrace(move || {
|
|
// FIXME: can we just pass `info` along rather than taking it apart here, only to have
|
|
// `rust_panic_with_hook` construct a new `PanicInfo`?
|
|
if let Some(msg) = msg.as_str() {
|
|
rust_panic_with_hook(
|
|
&mut StaticStrPayload(msg),
|
|
info.message(),
|
|
loc,
|
|
info.can_unwind(),
|
|
info.force_no_backtrace(),
|
|
);
|
|
} else {
|
|
rust_panic_with_hook(
|
|
&mut FormatStringPayload::new(msg),
|
|
info.message(),
|
|
loc,
|
|
info.can_unwind(),
|
|
info.force_no_backtrace(),
|
|
);
|
|
}
|
|
})
|
|
}
|
|
|
|
/// This is the entry point of panicking for the non-format-string variants of
|
|
/// panic!() and assert!(). In particular, this is the only entry point that supports
|
|
/// arbitrary payloads, not just format strings.
|
|
#[unstable(feature = "libstd_sys_internals", reason = "used by the panic! macro", issue = "none")]
|
|
#[cfg_attr(not(any(test, doctest)), lang = "begin_panic")]
|
|
// lang item for CTFE panic support
|
|
// never inline unless panic_immediate_abort to avoid code
|
|
// bloat at the call sites as much as possible
|
|
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)]
|
|
#[cfg_attr(feature = "panic_immediate_abort", inline)]
|
|
#[track_caller]
|
|
#[rustc_do_not_const_check] // hooked by const-eval
|
|
pub const fn begin_panic<M: Any + Send>(msg: M) -> ! {
|
|
if cfg!(feature = "panic_immediate_abort") {
|
|
intrinsics::abort()
|
|
}
|
|
|
|
let loc = Location::caller();
|
|
return crate::sys_common::backtrace::__rust_end_short_backtrace(move || {
|
|
rust_panic_with_hook(
|
|
&mut Payload::new(msg),
|
|
None,
|
|
loc,
|
|
/* can_unwind */ true,
|
|
/* force_no_backtrace */ false,
|
|
)
|
|
});
|
|
|
|
struct Payload<A> {
|
|
inner: Option<A>,
|
|
}
|
|
|
|
impl<A: Send + 'static> Payload<A> {
|
|
fn new(inner: A) -> Payload<A> {
|
|
Payload { inner: Some(inner) }
|
|
}
|
|
}
|
|
|
|
unsafe impl<A: Send + 'static> PanicPayload for Payload<A> {
|
|
fn take_box(&mut self) -> *mut (dyn Any + Send) {
|
|
// Note that this should be the only allocation performed in this code path. Currently
|
|
// this means that panic!() on OOM will invoke this code path, but then again we're not
|
|
// really ready for panic on OOM anyway. If we do start doing this, then we should
|
|
// propagate this allocation to be performed in the parent of this thread instead of the
|
|
// thread that's panicking.
|
|
let data = match self.inner.take() {
|
|
Some(a) => Box::new(a) as Box<dyn Any + Send>,
|
|
None => process::abort(),
|
|
};
|
|
Box::into_raw(data)
|
|
}
|
|
|
|
fn get(&mut self) -> &(dyn Any + Send) {
|
|
match self.inner {
|
|
Some(ref a) => a,
|
|
None => process::abort(),
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Central point for dispatching panics.
|
|
///
|
|
/// Executes the primary logic for a panic, including checking for recursive
|
|
/// panics, panic hooks, and finally dispatching to the panic runtime to either
|
|
/// abort or unwind.
|
|
fn rust_panic_with_hook(
|
|
payload: &mut dyn PanicPayload,
|
|
message: Option<&fmt::Arguments<'_>>,
|
|
location: &Location<'_>,
|
|
can_unwind: bool,
|
|
force_no_backtrace: bool,
|
|
) -> ! {
|
|
let must_abort = panic_count::increase(true);
|
|
|
|
// Check if we need to abort immediately.
|
|
if let Some(must_abort) = must_abort {
|
|
match must_abort {
|
|
panic_count::MustAbort::PanicInHook => {
|
|
// Don't try to format the message in this case, perhaps that is causing the
|
|
// recursive panics. However if the message is just a string, no user-defined
|
|
// code is involved in printing it, so that is risk-free.
|
|
let msg_str = message.and_then(|m| m.as_str()).map(|m| [m]);
|
|
let message = msg_str.as_ref().map(|m| fmt::Arguments::new_const(m));
|
|
let panicinfo = PanicInfo::internal_constructor(
|
|
message.as_ref(),
|
|
location,
|
|
can_unwind,
|
|
force_no_backtrace,
|
|
);
|
|
rtprintpanic!("{panicinfo}\nthread panicked while processing panic. aborting.\n");
|
|
}
|
|
panic_count::MustAbort::AlwaysAbort => {
|
|
// Unfortunately, this does not print a backtrace, because creating
|
|
// a `Backtrace` will allocate, which we must avoid here.
|
|
let panicinfo = PanicInfo::internal_constructor(
|
|
message,
|
|
location,
|
|
can_unwind,
|
|
force_no_backtrace,
|
|
);
|
|
rtprintpanic!("{panicinfo}\npanicked after panic::always_abort(), aborting.\n");
|
|
}
|
|
}
|
|
crate::sys::abort_internal();
|
|
}
|
|
|
|
let mut info =
|
|
PanicInfo::internal_constructor(message, location, can_unwind, force_no_backtrace);
|
|
let hook = HOOK.read().unwrap_or_else(PoisonError::into_inner);
|
|
match *hook {
|
|
// Some platforms (like wasm) know that printing to stderr won't ever actually
|
|
// print anything, and if that's the case we can skip the default
|
|
// hook. Since string formatting happens lazily when calling `payload`
|
|
// methods, this means we avoid formatting the string at all!
|
|
// (The panic runtime might still call `payload.take_box()` though and trigger
|
|
// formatting.)
|
|
Hook::Default if panic_output().is_none() => {}
|
|
Hook::Default => {
|
|
info.set_payload(payload.get());
|
|
default_hook(&info);
|
|
}
|
|
Hook::Custom(ref hook) => {
|
|
info.set_payload(payload.get());
|
|
hook(&info);
|
|
}
|
|
};
|
|
drop(hook);
|
|
|
|
// Indicate that we have finished executing the panic hook. After this point
|
|
// it is fine if there is a panic while executing destructors, as long as it
|
|
// it contained within a `catch_unwind`.
|
|
panic_count::finished_panic_hook();
|
|
|
|
if !can_unwind {
|
|
// If a thread panics while running destructors or tries to unwind
|
|
// through a nounwind function (e.g. extern "C") then we cannot continue
|
|
// unwinding and have to abort immediately.
|
|
rtprintpanic!("thread caused non-unwinding panic. aborting.\n");
|
|
crate::sys::abort_internal();
|
|
}
|
|
|
|
rust_panic(payload)
|
|
}
|
|
|
|
/// This is the entry point for `resume_unwind`.
|
|
/// It just forwards the payload to the panic runtime.
|
|
#[cfg_attr(feature = "panic_immediate_abort", inline)]
|
|
pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! {
|
|
panic_count::increase(false);
|
|
|
|
struct RewrapBox(Box<dyn Any + Send>);
|
|
|
|
unsafe impl PanicPayload for RewrapBox {
|
|
fn take_box(&mut self) -> *mut (dyn Any + Send) {
|
|
Box::into_raw(mem::replace(&mut self.0, Box::new(())))
|
|
}
|
|
|
|
fn get(&mut self) -> &(dyn Any + Send) {
|
|
&*self.0
|
|
}
|
|
}
|
|
|
|
rust_panic(&mut RewrapBox(payload))
|
|
}
|
|
|
|
/// An unmangled function (through `rustc_std_internal_symbol`) on which to slap
|
|
/// yer breakpoints.
|
|
#[inline(never)]
|
|
#[cfg_attr(not(test), rustc_std_internal_symbol)]
|
|
#[cfg(not(feature = "panic_immediate_abort"))]
|
|
fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
|
|
let code = unsafe { __rust_start_panic(msg) };
|
|
rtabort!("failed to initiate panic, error {code}")
|
|
}
|
|
|
|
#[cfg_attr(not(test), rustc_std_internal_symbol)]
|
|
#[cfg(feature = "panic_immediate_abort")]
|
|
fn rust_panic(_: &mut dyn PanicPayload) -> ! {
|
|
unsafe {
|
|
crate::intrinsics::abort();
|
|
}
|
|
}
|