1//! Implementation of panics via stack unwinding
2//!
3//! This crate is an implementation of panics in Rust using "most native" stack
4//! unwinding mechanism of the platform this is being compiled for. This
5//! essentially gets categorized into three buckets currently:
6//!
7//! 1. MSVC targets use SEH in the `seh.rs` file.
8//! 2. Emscripten uses C++ exceptions in the `emcc.rs` file.
9//! 3. All other targets use libunwind/libgcc in the `gcc.rs` file.
10//!
11//! More documentation about each implementation can be found in the respective
12//! module.
13
14#![no_std]
15#![unstable(feature = "panic_unwind", issue = "32837")]
16#![doc(issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/")]
17#![feature(cfg_emscripten_wasm_eh)]
18#![feature(core_intrinsics)]
19#![feature(lang_items)]
20#![feature(panic_unwind)]
21#![feature(staged_api)]
22#![feature(std_internals)]
23#![feature(rustc_attrs)]
24#![panic_runtime]
25#![feature(panic_runtime)]
26// `real_imp` is unused with Miri, so silence warnings.
27#![cfg_attr(miri, allow(dead_code))]
28#![allow(internal_features)]
29#![warn(unreachable_pub)]
30#![deny(unsafe_op_in_unsafe_fn)]
31
32use alloc::boxed::Box;
33use core::any::Any;
34use core::panic::PanicPayload;
35
36cfg_if::cfg_if! {
37 if #[cfg(all(target_os = "emscripten", not(emscripten_wasm_eh)))] {
38 #[path = "emcc.rs"]
39 mod imp;
40 } else if #[cfg(target_os = "hermit")] {
41 #[path = "hermit.rs"]
42 mod imp;
43 } else if #[cfg(target_os = "l4re")] {
44 // L4Re is unix family but does not yet support unwinding.
45 #[path = "dummy.rs"]
46 mod imp;
47 } else if #[cfg(any(
48 all(target_family = "windows", target_env = "gnu"),
49 target_os = "psp",
50 target_os = "xous",
51 target_os = "solid_asp3",
52 all(target_family = "unix", not(any(target_os = "espidf", target_os = "nuttx"))),
53 all(target_vendor = "fortanix", target_env = "sgx"),
54 target_family = "wasm",
55 ))] {
56 #[path = "gcc.rs"]
57 mod imp;
58 } else if #[cfg(miri)] {
59 // Use the Miri runtime on Windows as miri doesn't support funclet based unwinding,
60 // only landingpad based unwinding. Also use the Miri runtime on unsupported platforms.
61 #[path = "miri.rs"]
62 mod imp;
63 } else if #[cfg(all(target_env = "msvc", not(target_arch = "arm")))] {
64 // LLVM does not support unwinding on 32 bit ARM msvc (thumbv7a-pc-windows-msvc)
65 #[path = "seh.rs"]
66 mod imp;
67 } else {
68 // Targets that don't support unwinding.
69 // - os=none ("bare metal" targets)
70 // - os=uefi
71 // - os=espidf
72 // - nvptx64-nvidia-cuda
73 // - arch=avr
74 #[path = "dummy.rs"]
75 mod imp;
76 }
77}
78
79unsafe extern "C" {
80 /// Handler in std called when a panic object is dropped outside of
81 /// `catch_unwind`.
82 #[rustc_std_internal_symbol]
83 unsafefn __rust_drop_panic() -> !;
84
85 /// Handler in std called when a foreign exception is caught.
86 #[rustc_std_internal_symbol]
87 unsafefn __rust_foreign_exception() -> !;
88}
89
90#[rustc_std_internal_symbol]
91#[allow(improper_ctypes_definitions)]
92pub unsafe extern "C" fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static) {
93 unsafe { Box::into_raw(imp::cleanup(ptr:payload)) }
94}
95
96// Entry point for raising an exception, just delegates to the platform-specific
97// implementation.
98#[rustc_std_internal_symbol]
99pub unsafe fn __rust_start_panic(payload: &mut dyn PanicPayload) -> u32 {
100 unsafe {
101 let payload: Box = Box::from_raw(payload.take_box());
102
103 imp::panic(data:payload)
104 }
105}
106