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a7813a04 XL |
1 | //! Implementation of various bits and pieces of the `panic!` macro and |
2 | //! associated runtime pieces. | |
3 | //! | |
4 | //! Specifically, this module contains the implementation of: | |
5 | //! | |
6 | //! * Panic hooks | |
7 | //! * Executing a panic up to doing the actual implementation | |
8 | //! * Shims around "try" | |
9 | ||
532ac7d7 XL |
10 | use core::panic::{BoxMeUp, PanicInfo, Location}; |
11 | ||
12 | use crate::any::Any; | |
13 | use crate::fmt; | |
14 | use crate::intrinsics; | |
e74abb32 | 15 | use crate::mem::{self, ManuallyDrop}; |
532ac7d7 | 16 | use crate::raw; |
e74abb32 | 17 | use crate::sync::atomic::{AtomicBool, Ordering}; |
532ac7d7 XL |
18 | use crate::sys::stdio::panic_output; |
19 | use crate::sys_common::rwlock::RWLock; | |
e74abb32 XL |
20 | use crate::sys_common::{thread_info, util}; |
21 | use crate::sys_common::backtrace::{self, RustBacktrace}; | |
532ac7d7 | 22 | use crate::thread; |
60c5eb7d | 23 | use crate::process; |
532ac7d7 XL |
24 | |
25 | #[cfg(not(test))] | |
26 | use crate::io::set_panic; | |
27 | // make sure to use the stderr output configured | |
28 | // by libtest in the real copy of std | |
29 | #[cfg(test)] | |
30 | use realstd::io::set_panic; | |
1a4d82fc | 31 | |
a7813a04 XL |
32 | // Binary interface to the panic runtime that the standard library depends on. |
33 | // | |
34 | // The standard library is tagged with `#![needs_panic_runtime]` (introduced in | |
35 | // RFC 1513) to indicate that it requires some other crate tagged with | |
36 | // `#![panic_runtime]` to exist somewhere. Each panic runtime is intended to | |
37 | // implement these symbols (with the same signatures) so we can get matched up | |
38 | // to them. | |
39 | // | |
40 | // One day this may look a little less ad-hoc with the compiler helping out to | |
41 | // hook up these functions, but it is not this day! | |
42 | #[allow(improper_ctypes)] | |
43 | extern { | |
44 | fn __rust_maybe_catch_panic(f: fn(*mut u8), | |
45 | data: *mut u8, | |
46 | data_ptr: *mut usize, | |
47 | vtable_ptr: *mut usize) -> u32; | |
60c5eb7d XL |
48 | |
49 | /// `payload` is actually a `*mut &mut dyn BoxMeUp` but that would cause FFI warnings. | |
50 | /// It cannot be `Box<dyn BoxMeUp>` because the other end of this call does not depend | |
51 | /// on liballoc, and thus cannot use `Box`. | |
83c7162d XL |
52 | #[unwind(allowed)] |
53 | fn __rust_start_panic(payload: usize) -> u32; | |
a7813a04 XL |
54 | } |
55 | ||
9cc50fc6 | 56 | #[derive(Copy, Clone)] |
54a0048b | 57 | enum Hook { |
9cc50fc6 | 58 | Default, |
532ac7d7 | 59 | Custom(*mut (dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send)), |
9cc50fc6 SL |
60 | } |
61 | ||
a7813a04 | 62 | static HOOK_LOCK: RWLock = RWLock::new(); |
54a0048b | 63 | static mut HOOK: Hook = Hook::Default; |
9cc50fc6 | 64 | |
54a0048b | 65 | /// Registers a custom panic hook, replacing any that was previously registered. |
9cc50fc6 | 66 | /// |
a7813a04 XL |
67 | /// The panic hook is invoked when a thread panics, but before the panic runtime |
68 | /// is invoked. As such, the hook will run with both the aborting and unwinding | |
69 | /// runtimes. The default hook prints a message to standard error and generates | |
70 | /// a backtrace if requested, but this behavior can be customized with the | |
83c7162d XL |
71 | /// `set_hook` and [`take_hook`] functions. |
72 | /// | |
73 | /// [`take_hook`]: ./fn.take_hook.html | |
9cc50fc6 | 74 | /// |
54a0048b | 75 | /// The hook is provided with a `PanicInfo` struct which contains information |
9cc50fc6 SL |
76 | /// about the origin of the panic, including the payload passed to `panic!` and |
77 | /// the source code location from which the panic originated. | |
78 | /// | |
54a0048b | 79 | /// The panic hook is a global resource. |
9cc50fc6 SL |
80 | /// |
81 | /// # Panics | |
82 | /// | |
83 | /// Panics if called from a panicking thread. | |
9e0c209e SL |
84 | /// |
85 | /// # Examples | |
86 | /// | |
87 | /// The following will print "Custom panic hook": | |
88 | /// | |
89 | /// ```should_panic | |
90 | /// use std::panic; | |
91 | /// | |
92 | /// panic::set_hook(Box::new(|_| { | |
93 | /// println!("Custom panic hook"); | |
94 | /// })); | |
95 | /// | |
96 | /// panic!("Normal panic"); | |
97 | /// ``` | |
a7813a04 | 98 | #[stable(feature = "panic_hooks", since = "1.10.0")] |
532ac7d7 | 99 | pub fn set_hook(hook: Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>) { |
9cc50fc6 | 100 | if thread::panicking() { |
54a0048b | 101 | panic!("cannot modify the panic hook from a panicking thread"); |
9cc50fc6 SL |
102 | } |
103 | ||
9cc50fc6 | 104 | unsafe { |
a7813a04 | 105 | HOOK_LOCK.write(); |
54a0048b SL |
106 | let old_hook = HOOK; |
107 | HOOK = Hook::Custom(Box::into_raw(hook)); | |
a7813a04 | 108 | HOOK_LOCK.write_unlock(); |
9cc50fc6 | 109 | |
54a0048b | 110 | if let Hook::Custom(ptr) = old_hook { |
dc9dc135 XL |
111 | #[allow(unused_must_use)] { |
112 | Box::from_raw(ptr); | |
113 | } | |
9cc50fc6 SL |
114 | } |
115 | } | |
116 | } | |
117 | ||
54a0048b | 118 | /// Unregisters the current panic hook, returning it. |
9cc50fc6 | 119 | /// |
83c7162d XL |
120 | /// *See also the function [`set_hook`].* |
121 | /// | |
122 | /// [`set_hook`]: ./fn.set_hook.html | |
123 | /// | |
54a0048b | 124 | /// If no custom hook is registered, the default hook will be returned. |
9cc50fc6 SL |
125 | /// |
126 | /// # Panics | |
127 | /// | |
128 | /// Panics if called from a panicking thread. | |
9e0c209e SL |
129 | /// |
130 | /// # Examples | |
131 | /// | |
132 | /// The following will print "Normal panic": | |
133 | /// | |
134 | /// ```should_panic | |
135 | /// use std::panic; | |
136 | /// | |
137 | /// panic::set_hook(Box::new(|_| { | |
138 | /// println!("Custom panic hook"); | |
139 | /// })); | |
140 | /// | |
141 | /// let _ = panic::take_hook(); | |
142 | /// | |
143 | /// panic!("Normal panic"); | |
144 | /// ``` | |
a7813a04 | 145 | #[stable(feature = "panic_hooks", since = "1.10.0")] |
532ac7d7 | 146 | pub fn take_hook() -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send> { |
9cc50fc6 | 147 | if thread::panicking() { |
54a0048b | 148 | panic!("cannot modify the panic hook from a panicking thread"); |
9cc50fc6 SL |
149 | } |
150 | ||
151 | unsafe { | |
a7813a04 | 152 | HOOK_LOCK.write(); |
54a0048b SL |
153 | let hook = HOOK; |
154 | HOOK = Hook::Default; | |
a7813a04 | 155 | HOOK_LOCK.write_unlock(); |
9cc50fc6 | 156 | |
54a0048b SL |
157 | match hook { |
158 | Hook::Default => Box::new(default_hook), | |
476ff2be | 159 | Hook::Custom(ptr) => Box::from_raw(ptr), |
9cc50fc6 SL |
160 | } |
161 | } | |
162 | } | |
163 | ||
532ac7d7 | 164 | fn default_hook(info: &PanicInfo<'_>) { |
9cc50fc6 SL |
165 | // If this is a double panic, make sure that we print a backtrace |
166 | // for this panic. Otherwise only print it if logging is enabled. | |
e74abb32 XL |
167 | let backtrace_env = if update_panic_count(0) >= 2 { |
168 | RustBacktrace::Print(backtrace_rs::PrintFmt::Full) | |
e1599b0c | 169 | } else { |
e74abb32 | 170 | backtrace::rust_backtrace_env() |
5bcae85e | 171 | }; |
9cc50fc6 | 172 | |
dc9dc135 XL |
173 | // The current implementation always returns `Some`. |
174 | let location = info.location().unwrap(); | |
9cc50fc6 | 175 | |
0531ce1d | 176 | let msg = match info.payload().downcast_ref::<&'static str>() { |
1a4d82fc | 177 | Some(s) => *s, |
0531ce1d | 178 | None => match info.payload().downcast_ref::<String>() { |
85aaf69f | 179 | Some(s) => &s[..], |
1a4d82fc JJ |
180 | None => "Box<Any>", |
181 | } | |
182 | }; | |
d9579d0f AL |
183 | let thread = thread_info::current_thread(); |
184 | let name = thread.as_ref().and_then(|t| t.name()).unwrap_or("<unnamed>"); | |
b039eaaf | 185 | |
532ac7d7 | 186 | let write = |err: &mut dyn crate::io::Write| { |
83c7162d XL |
187 | let _ = writeln!(err, "thread '{}' panicked at '{}', {}", |
188 | name, msg, location); | |
7453a54e | 189 | |
e74abb32 | 190 | static FIRST_PANIC: AtomicBool = AtomicBool::new(true); |
5bcae85e | 191 | |
e74abb32 XL |
192 | match backtrace_env { |
193 | RustBacktrace::Print(format) => drop(backtrace::print(err, format)), | |
194 | RustBacktrace::Disabled => {} | |
195 | RustBacktrace::RuntimeDisabled => { | |
196 | if FIRST_PANIC.swap(false, Ordering::SeqCst) { | |
197 | let _ = writeln!(err, "note: run with `RUST_BACKTRACE=1` \ | |
198 | environment variable to display a backtrace."); | |
199 | } | |
5bcae85e | 200 | } |
b039eaaf SL |
201 | } |
202 | }; | |
203 | ||
532ac7d7 XL |
204 | if let Some(mut local) = set_panic(None) { |
205 | // NB. In `cfg(test)` this uses the forwarding impl | |
206 | // for `Box<dyn (::realstd::io::Write) + Send>`. | |
207 | write(&mut local); | |
208 | set_panic(Some(local)); | |
0731742a XL |
209 | } else if let Some(mut out) = panic_output() { |
210 | write(&mut out); | |
1a4d82fc | 211 | } |
b039eaaf | 212 | } |
1a4d82fc | 213 | |
5bcae85e SL |
214 | |
215 | #[cfg(not(test))] | |
216 | #[doc(hidden)] | |
217 | #[unstable(feature = "update_panic_count", issue = "0")] | |
218 | pub fn update_panic_count(amt: isize) -> usize { | |
532ac7d7 | 219 | use crate::cell::Cell; |
5bcae85e SL |
220 | thread_local! { static PANIC_COUNT: Cell<usize> = Cell::new(0) } |
221 | ||
222 | PANIC_COUNT.with(|c| { | |
223 | let next = (c.get() as isize + amt) as usize; | |
224 | c.set(next); | |
e74abb32 | 225 | next |
5bcae85e SL |
226 | }) |
227 | } | |
228 | ||
229 | #[cfg(test)] | |
230 | pub use realstd::rt::update_panic_count; | |
231 | ||
a7813a04 | 232 | /// Invoke a closure, capturing the cause of an unwinding panic if one occurs. |
532ac7d7 | 233 | pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> { |
8bb4bdeb | 234 | union Data<F, R> { |
e74abb32 XL |
235 | f: ManuallyDrop<F>, |
236 | r: ManuallyDrop<R>, | |
5bcae85e | 237 | } |
a7813a04 | 238 | |
5bcae85e | 239 | // We do some sketchy operations with ownership here for the sake of |
8bb4bdeb XL |
240 | // performance. We can only pass pointers down to |
241 | // `__rust_maybe_catch_panic` (can't pass objects by value), so we do all | |
242 | // the ownership tracking here manually using a union. | |
5bcae85e | 243 | // |
8bb4bdeb | 244 | // We go through a transition where: |
5bcae85e | 245 | // |
8bb4bdeb | 246 | // * First, we set the data to be the closure that we're going to call. |
5bcae85e | 247 | // * When we make the function call, the `do_call` function below, we take |
8bb4bdeb XL |
248 | // ownership of the function pointer. At this point the `Data` union is |
249 | // entirely uninitialized. | |
5bcae85e SL |
250 | // * If the closure successfully returns, we write the return value into the |
251 | // data's return slot. Note that `ptr::write` is used as it's overwriting | |
252 | // uninitialized data. | |
253 | // * Finally, when we come back out of the `__rust_maybe_catch_panic` we're | |
254 | // in one of two states: | |
255 | // | |
256 | // 1. The closure didn't panic, in which case the return value was | |
8bb4bdeb | 257 | // filled in. We move it out of `data` and return it. |
5bcae85e | 258 | // 2. The closure panicked, in which case the return value wasn't |
8bb4bdeb XL |
259 | // filled in. In this case the entire `data` union is invalid, so |
260 | // there is no need to drop anything. | |
5bcae85e SL |
261 | // |
262 | // Once we stack all that together we should have the "most efficient' | |
263 | // method of calling a catch panic whilst juggling ownership. | |
264 | let mut any_data = 0; | |
265 | let mut any_vtable = 0; | |
266 | let mut data = Data { | |
e74abb32 | 267 | f: ManuallyDrop::new(f) |
5bcae85e | 268 | }; |
b039eaaf | 269 | |
5bcae85e SL |
270 | let r = __rust_maybe_catch_panic(do_call::<F, R>, |
271 | &mut data as *mut _ as *mut u8, | |
272 | &mut any_data, | |
273 | &mut any_vtable); | |
274 | ||
275 | return if r == 0 { | |
5bcae85e | 276 | debug_assert!(update_panic_count(0) == 0); |
e74abb32 | 277 | Ok(ManuallyDrop::into_inner(data.r)) |
5bcae85e | 278 | } else { |
5bcae85e SL |
279 | update_panic_count(-1); |
280 | debug_assert!(update_panic_count(0) == 0); | |
281 | Err(mem::transmute(raw::TraitObject { | |
282 | data: any_data as *mut _, | |
283 | vtable: any_vtable as *mut _, | |
284 | })) | |
285 | }; | |
a7813a04 | 286 | |
5bcae85e SL |
287 | fn do_call<F: FnOnce() -> R, R>(data: *mut u8) { |
288 | unsafe { | |
289 | let data = data as *mut Data<F, R>; | |
e74abb32 XL |
290 | let data = &mut (*data); |
291 | let f = ManuallyDrop::take(&mut data.f); | |
292 | data.r = ManuallyDrop::new(f()); | |
5bcae85e | 293 | } |
a7813a04 XL |
294 | } |
295 | } | |
296 | ||
297 | /// Determines whether the current thread is unwinding because of panic. | |
298 | pub fn panicking() -> bool { | |
5bcae85e | 299 | update_panic_count(0) != 0 |
a7813a04 XL |
300 | } |
301 | ||
a7813a04 XL |
302 | /// The entry point for panicking with a formatted message. |
303 | /// | |
304 | /// This is designed to reduce the amount of code required at the call | |
305 | /// site as much as possible (so that `panic!()` has as low an impact | |
306 | /// on (e.g.) the inlining of other functions as possible), by moving | |
307 | /// the actual formatting into this shared place. | |
308 | #[unstable(feature = "libstd_sys_internals", | |
309 | reason = "used by the panic! macro", | |
310 | issue = "0")] | |
a1dfa0c6 XL |
311 | #[cold] |
312 | // If panic_immediate_abort, inline the abort call, | |
313 | // otherwise avoid inlining because of it is cold path. | |
314 | #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))] | |
315 | #[cfg_attr( feature="panic_immediate_abort" ,inline)] | |
532ac7d7 | 316 | pub fn begin_panic_fmt(msg: &fmt::Arguments<'_>, |
041b39d2 | 317 | file_line_col: &(&'static str, u32, u32)) -> ! { |
a1dfa0c6 XL |
318 | if cfg!(feature = "panic_immediate_abort") { |
319 | unsafe { intrinsics::abort() } | |
320 | } | |
321 | ||
60c5eb7d | 322 | // Just package everything into a `PanicInfo` and continue like libcore panics. |
8faf50e0 | 323 | let (file, line, col) = *file_line_col; |
e74abb32 XL |
324 | let location = Location::internal_constructor(file, line, col); |
325 | let info = PanicInfo::internal_constructor(Some(msg), &location); | |
60c5eb7d | 326 | begin_panic_handler(&info) |
94b46f34 | 327 | } |
83c7162d | 328 | |
60c5eb7d XL |
329 | /// Entry point of panics from the libcore crate (`panic_impl` lang item). |
330 | #[cfg_attr(not(test), panic_handler)] | |
331 | #[unwind(allowed)] | |
332 | pub fn begin_panic_handler(info: &PanicInfo<'_>) -> ! { | |
8faf50e0 XL |
333 | struct PanicPayload<'a> { |
334 | inner: &'a fmt::Arguments<'a>, | |
335 | string: Option<String>, | |
83c7162d XL |
336 | } |
337 | ||
8faf50e0 XL |
338 | impl<'a> PanicPayload<'a> { |
339 | fn new(inner: &'a fmt::Arguments<'a>) -> PanicPayload<'a> { | |
340 | PanicPayload { inner, string: None } | |
341 | } | |
83c7162d | 342 | |
8faf50e0 | 343 | fn fill(&mut self) -> &mut String { |
532ac7d7 | 344 | use crate::fmt::Write; |
83c7162d | 345 | |
8faf50e0 | 346 | let inner = self.inner; |
60c5eb7d | 347 | // Lazily, the first time this gets called, run the actual string formatting. |
8faf50e0 XL |
348 | self.string.get_or_insert_with(|| { |
349 | let mut s = String::new(); | |
350 | drop(s.write_fmt(*inner)); | |
351 | s | |
352 | }) | |
353 | } | |
94b46f34 | 354 | } |
83c7162d | 355 | |
8faf50e0 | 356 | unsafe impl<'a> BoxMeUp for PanicPayload<'a> { |
60c5eb7d | 357 | fn take_box(&mut self) -> *mut (dyn Any + Send) { |
416331ca | 358 | let contents = mem::take(self.fill()); |
8faf50e0 XL |
359 | Box::into_raw(Box::new(contents)) |
360 | } | |
041b39d2 | 361 | |
8faf50e0 XL |
362 | fn get(&mut self) -> &(dyn Any + Send) { |
363 | self.fill() | |
364 | } | |
365 | } | |
94b46f34 | 366 | |
94b46f34 XL |
367 | // We do two allocations here, unfortunately. But (a) they're |
368 | // required with the current scheme, and (b) we don't handle | |
369 | // panic + OOM properly anyway (see comment in begin_panic | |
370 | // below). | |
371 | ||
372 | let loc = info.location().unwrap(); // The current implementation always returns Some | |
373 | let msg = info.message().unwrap(); // The current implementation always returns Some | |
374 | let file_line_col = (loc.file(), loc.line(), loc.column()); | |
375 | rust_panic_with_hook( | |
376 | &mut PanicPayload::new(msg), | |
377 | info.message(), | |
378 | &file_line_col); | |
379 | } | |
380 | ||
60c5eb7d XL |
381 | /// This is the entry point of panicking for the non-format-string variants of |
382 | /// panic!() and assert!(). In particular, this is the only entry point that supports | |
383 | /// arbitrary payloads, not just format strings. | |
a7813a04 XL |
384 | #[unstable(feature = "libstd_sys_internals", |
385 | reason = "used by the panic! macro", | |
386 | issue = "0")] | |
60c5eb7d | 387 | #[cfg_attr(not(test), lang = "begin_panic")] // lang item for CTFE panic support |
a1dfa0c6 XL |
388 | // never inline unless panic_immediate_abort to avoid code |
389 | // bloat at the call sites as much as possible | |
390 | #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))] | |
391 | #[cold] | |
3b2f2976 | 392 | pub fn begin_panic<M: Any + Send>(msg: M, file_line_col: &(&'static str, u32, u32)) -> ! { |
a1dfa0c6 XL |
393 | if cfg!(feature = "panic_immediate_abort") { |
394 | unsafe { intrinsics::abort() } | |
395 | } | |
396 | ||
a7813a04 XL |
397 | // Note that this should be the only allocation performed in this code path. |
398 | // Currently this means that panic!() on OOM will invoke this code path, | |
399 | // but then again we're not really ready for panic on OOM anyway. If | |
400 | // we do start doing this, then we should propagate this allocation to | |
401 | // be performed in the parent of this thread instead of the thread that's | |
402 | // panicking. | |
403 | ||
83c7162d XL |
404 | rust_panic_with_hook(&mut PanicPayload::new(msg), None, file_line_col); |
405 | ||
406 | struct PanicPayload<A> { | |
407 | inner: Option<A>, | |
408 | } | |
409 | ||
410 | impl<A: Send + 'static> PanicPayload<A> { | |
411 | fn new(inner: A) -> PanicPayload<A> { | |
412 | PanicPayload { inner: Some(inner) } | |
413 | } | |
414 | } | |
415 | ||
416 | unsafe impl<A: Send + 'static> BoxMeUp for PanicPayload<A> { | |
60c5eb7d | 417 | fn take_box(&mut self) -> *mut (dyn Any + Send) { |
83c7162d | 418 | let data = match self.inner.take() { |
8faf50e0 | 419 | Some(a) => Box::new(a) as Box<dyn Any + Send>, |
60c5eb7d | 420 | None => process::abort(), |
83c7162d XL |
421 | }; |
422 | Box::into_raw(data) | |
423 | } | |
424 | ||
8faf50e0 | 425 | fn get(&mut self) -> &(dyn Any + Send) { |
83c7162d XL |
426 | match self.inner { |
427 | Some(ref a) => a, | |
60c5eb7d | 428 | None => process::abort(), |
83c7162d XL |
429 | } |
430 | } | |
431 | } | |
a7813a04 XL |
432 | } |
433 | ||
83c7162d | 434 | /// Central point for dispatching panics. |
a7813a04 | 435 | /// |
83c7162d XL |
436 | /// Executes the primary logic for a panic, including checking for recursive |
437 | /// panics, panic hooks, and finally dispatching to the panic runtime to either | |
438 | /// abort or unwind. | |
8faf50e0 | 439 | fn rust_panic_with_hook(payload: &mut dyn BoxMeUp, |
532ac7d7 | 440 | message: Option<&fmt::Arguments<'_>>, |
94b46f34 | 441 | file_line_col: &(&str, u32, u32)) -> ! { |
041b39d2 | 442 | let (file, line, col) = *file_line_col; |
a7813a04 | 443 | |
5bcae85e | 444 | let panics = update_panic_count(1); |
a7813a04 | 445 | |
0731742a | 446 | // If this is the third nested call (e.g., panics == 2, this is 0-indexed), |
a7813a04 XL |
447 | // the panic hook probably triggered the last panic, otherwise the |
448 | // double-panic check would have aborted the process. In this case abort the | |
449 | // process real quickly as we don't want to try calling it again as it'll | |
450 | // probably just panic again. | |
5bcae85e | 451 | if panics > 2 { |
b039eaaf | 452 | util::dumb_print(format_args!("thread panicked while processing \ |
9cc50fc6 | 453 | panic. aborting.\n")); |
b039eaaf SL |
454 | unsafe { intrinsics::abort() } |
455 | } | |
456 | ||
9cc50fc6 | 457 | unsafe { |
e74abb32 XL |
458 | let location = Location::internal_constructor(file, line, col); |
459 | let mut info = PanicInfo::internal_constructor(message, &location); | |
a7813a04 | 460 | HOOK_LOCK.read(); |
54a0048b | 461 | match HOOK { |
60c5eb7d | 462 | // Some platforms (like wasm) know that printing to stderr won't ever actually |
83c7162d | 463 | // print anything, and if that's the case we can skip the default |
60c5eb7d XL |
464 | // hook. Since string formatting happens lazily when calling `payload` |
465 | // methods, this means we avoid formatting the string at all! | |
466 | // (The panic runtime might still call `payload.take_box()` though and trigger | |
467 | // formatting.) | |
0731742a | 468 | Hook::Default if panic_output().is_none() => {} |
83c7162d XL |
469 | Hook::Default => { |
470 | info.set_payload(payload.get()); | |
471 | default_hook(&info); | |
472 | } | |
473 | Hook::Custom(ptr) => { | |
474 | info.set_payload(payload.get()); | |
475 | (*ptr)(&info); | |
476 | } | |
0731742a | 477 | }; |
a7813a04 | 478 | HOOK_LOCK.read_unlock(); |
9cc50fc6 | 479 | } |
b039eaaf | 480 | |
5bcae85e | 481 | if panics > 1 { |
b039eaaf SL |
482 | // If a thread panics while it's already unwinding then we |
483 | // have limited options. Currently our preference is to | |
484 | // just abort. In the future we may consider resuming | |
485 | // unwinding or otherwise exiting the thread cleanly. | |
486 | util::dumb_print(format_args!("thread panicked while panicking. \ | |
9cc50fc6 | 487 | aborting.\n")); |
b039eaaf | 488 | unsafe { intrinsics::abort() } |
1a4d82fc | 489 | } |
a7813a04 | 490 | |
0531ce1d | 491 | rust_panic(payload) |
a7813a04 XL |
492 | } |
493 | ||
60c5eb7d XL |
494 | /// This is the entry point for `resume_unwind`. |
495 | /// It just forwards the payload to the panic runtime. | |
496 | pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! { | |
5bcae85e | 497 | update_panic_count(1); |
83c7162d | 498 | |
8faf50e0 | 499 | struct RewrapBox(Box<dyn Any + Send>); |
83c7162d XL |
500 | |
501 | unsafe impl BoxMeUp for RewrapBox { | |
60c5eb7d | 502 | fn take_box(&mut self) -> *mut (dyn Any + Send) { |
83c7162d XL |
503 | Box::into_raw(mem::replace(&mut self.0, Box::new(()))) |
504 | } | |
505 | ||
8faf50e0 | 506 | fn get(&mut self) -> &(dyn Any + Send) { |
83c7162d XL |
507 | &*self.0 |
508 | } | |
509 | } | |
510 | ||
60c5eb7d | 511 | rust_panic(&mut RewrapBox(payload)) |
5bcae85e SL |
512 | } |
513 | ||
0bf4aa26 XL |
514 | /// An unmangled function (through `rustc_std_internal_symbol`) on which to slap |
515 | /// yer breakpoints. | |
516 | #[inline(never)] | |
517 | #[cfg_attr(not(test), rustc_std_internal_symbol)] | |
518 | fn rust_panic(mut msg: &mut dyn BoxMeUp) -> ! { | |
a7813a04 | 519 | let code = unsafe { |
8faf50e0 | 520 | let obj = &mut msg as *mut &mut dyn BoxMeUp; |
83c7162d | 521 | __rust_start_panic(obj as usize) |
a7813a04 XL |
522 | }; |
523 | rtabort!("failed to initiate panic, error {}", code) | |
1a4d82fc | 524 | } |