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//! Implementation of Rust panics via process aborts
//!
//! When compared to the implementation via unwinding, this crate is *much*
//! simpler! That being said, it's not quite as versatile, but here goes!
#![no_std]
#![unstable(feature = "panic_abort", issue = "32837")]
#![doc(
html_root_url = "https://doc.rust-lang.org/nightly/",
issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/"
)]
#![panic_runtime]
#![allow(unused_features)]
#![feature(core_intrinsics)]
#![feature(libc)]
#![feature(nll)]
#![feature(panic_runtime)]
#![feature(staged_api)]
#![feature(rustc_attrs)]
#![feature(llvm_asm)]
use core::any::Any;
#[rustc_std_internal_symbol]
#[allow(improper_ctypes_definitions)]
pub unsafe extern "C" fn __rust_panic_cleanup(_: *mut u8) -> *mut (dyn Any + Send + 'static) {
unreachable!()
}
// "Leak" the payload and shim to the relevant abort on the platform in question.
#[rustc_std_internal_symbol]
pub unsafe extern "C" fn __rust_start_panic(_payload: usize) -> u32 {
abort();
cfg_if::cfg_if! {
if #[cfg(any(unix, target_os = "cloudabi"))] {
unsafe fn abort() -> ! {
libc::abort();
}
} else if #[cfg(any(target_os = "hermit",
all(target_vendor = "fortanix", target_env = "sgx")
))] {
unsafe fn abort() -> ! {
// call std::sys::abort_internal
extern "C" {
pub fn __rust_abort() -> !;
}
__rust_abort();
}
} else if #[cfg(all(windows, any(target_arch = "x86", target_arch = "x86_64")))] {
// On Windows, use the processor-specific __fastfail mechanism. In Windows 8
// and later, this will terminate the process immediately without running any
// in-process exception handlers. In earlier versions of Windows, this
// sequence of instructions will be treated as an access violation,
// terminating the process but without necessarily bypassing all exception
// handlers.
//
// https://docs.microsoft.com/en-us/cpp/intrinsics/fastfail
//
// Note: this is the same implementation as in libstd's `abort_internal`
unsafe fn abort() -> ! {
llvm_asm!("int $$0x29" :: "{ecx}"(7) ::: volatile); // 7 is FAST_FAIL_FATAL_APP_EXIT
core::intrinsics::unreachable();
}
} else {
unsafe fn abort() -> ! {
core::intrinsics::abort();
}
}
}
}
// This... is a bit of an oddity. The tl;dr; is that this is required to link
// correctly, the longer explanation is below.
//
// Right now the binaries of libcore/libstd that we ship are all compiled with
// `-C panic=unwind`. This is done to ensure that the binaries are maximally
// compatible with as many situations as possible. The compiler, however,
// requires a "personality function" for all functions compiled with `-C
// panic=unwind`. This personality function is hardcoded to the symbol
// `rust_eh_personality` and is defined by the `eh_personality` lang item.
//
// So... why not just define that lang item here? Good question! The way that
// panic runtimes are linked in is actually a little subtle in that they're
// "sort of" in the compiler's crate store, but only actually linked if another
// isn't actually linked. This ends up meaning that both this crate and the
// panic_unwind crate can appear in the compiler's crate store, and if both
// define the `eh_personality` lang item then that'll hit an error.
//
// To handle this the compiler only requires the `eh_personality` is defined if
// the panic runtime being linked in is the unwinding runtime, and otherwise
// it's not required to be defined (rightfully so). In this case, however, this
// library just defines this symbol so there's at least some personality
// somewhere.
//
// Essentially this symbol is just defined to get wired up to libcore/libstd
// binaries, but it should never be called as we don't link in an unwinding
// runtime at all.
pub mod personalities {
#[rustc_std_internal_symbol]
#[cfg(not(any(
all(target_arch = "wasm32", not(target_os = "emscripten"),),
all(target_os = "windows", target_env = "gnu", target_arch = "x86_64",),
)))]
pub extern "C" fn rust_eh_personality() {}
// On x86_64-pc-windows-gnu we use our own personality function that needs
// to return `ExceptionContinueSearch` as we're passing on all our frames.
#[rustc_std_internal_symbol]
#[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86_64"))]
pub extern "C" fn rust_eh_personality(
_record: usize,
_frame: usize,
_context: usize,
_dispatcher: usize,
) -> u32 {
1 // `ExceptionContinueSearch`
}
// These two are called by our startup objects on i686-pc-windows-gnu, but
// they don't need to do anything so the bodies are nops.
#[rustc_std_internal_symbol]
#[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
pub extern "C" fn rust_eh_register_frames() {}
#[rustc_std_internal_symbol]
#[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
pub extern "C" fn rust_eh_unregister_frames() {}
}
|
