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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Implementation of various bits and pieces of the `panic!` macro and
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//! associated runtime pieces.
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use io::prelude::*;
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use any::Any;
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use cell::RefCell;
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use fmt;
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use mem;
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use ptr;
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use raw;
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use __core::fmt::Display;
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thread_local! {
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pub static LOCAL_STDERR: RefCell<Option<Box<Write + Send>>> = {
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RefCell::new(None)
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}
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}
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///The compiler wants this to be here. Otherwise it won't be happy. And we like happy compilers.
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#[lang = "eh_personality"]
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pub extern fn eh_personality() {}
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/// Entry point of panic from the libcore crate.
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#[lang = "panic_fmt"]
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pub extern fn rust_begin_panic(msg: fmt::Arguments, file: &'static str, line: u32) -> ! {
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begin_panic_fmt(&msg, &(file, line))
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}
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/// The entry point for panicking with a formatted message.
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///
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/// This is designed to reduce the amount of code required at the call
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/// site as much as possible (so that `panic!()` has as low an impact
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/// on (e.g.) the inlining of other functions as possible), by moving
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/// the actual formatting into this shared place.
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#[unstable(feature = "libstd_sys_internals",
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reason = "used by the panic! macro",
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issue = "0")]
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#[inline(never)] #[cold]
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pub fn begin_panic_fmt(msg: &fmt::Arguments, file_line: &(&'static str, u32)) -> ! {
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use fmt::Write;
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let mut s = String::new();
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let _ = s.write_fmt(*msg);
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begin_panic(s, file_line);
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}
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/// We don't have stack unwinding, so all we do is print the panic message
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/// and then loop forever
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#[inline(never)]
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#[cold]
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pub fn begin_panic<M: Any + Send + Display>(msg: M, file_line: &(&'static str, u32)) -> ! {
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let msg = Box::new(msg);
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let (file, line) = *file_line;
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use libctru::console::consoleInit;
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use libctru::gfx::gfxScreen_t;
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// set up a new console, overwriting whatever was on the top screen
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// before we started panicking
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let _console = unsafe { consoleInit(gfxScreen_t::GFX_TOP, ptr::null_mut()) };
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println!("PANIC in {} at line {}:", file, line);
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println!(" {}", msg);
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loop {}
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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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pub unsafe fn try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<Any + Send>> {
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#[allow(unions_with_drop_fields)]
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union Data<F, R> {
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f: F,
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r: R,
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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
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// `__rust_maybe_catch_panic` (can't pass objects by value), so we do all
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// the ownership tracking here manually 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 to be the 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. Note that `ptr::write` is used as it's overwriting
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// uninitialized data.
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// * Finally, when we come back out of the `__rust_maybe_catch_panic` we're
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// in one of two states:
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//
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// 1. The closure didn't panic, in which case the return value was
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// filled in. We move it out of `data` and return it.
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// 2. The closure panicked, in which case the return value wasn't
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// filled in. In this case the entire `data` union is invalid, so
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// there is no need to drop anything.
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//
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// Once we stack all that together we should have the "most efficient'
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// method of calling a catch panic whilst juggling ownership.
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let mut any_data = 0;
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let mut any_vtable = 0;
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let mut data = Data {
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f: f,
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};
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let r = __rust_maybe_catch_panic(do_call::<F, R>,
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&mut data as *mut _ as *mut u8,
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&mut any_data,
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&mut any_vtable);
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return if r == 0 {
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debug_assert!(update_panic_count(0) == 0);
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Ok(data.r)
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} else {
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update_panic_count(-1);
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debug_assert!(update_panic_count(0) == 0);
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Err(mem::transmute(raw::TraitObject {
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data: any_data as *mut _,
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vtable: any_vtable as *mut _,
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}))
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};
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fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
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unsafe {
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let data = data as *mut Data<F, R>;
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let f = ptr::read(&mut (*data).f);
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ptr::write(&mut (*data).r, f());
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}
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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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#[unstable(feature = "update_panic_count", issue = "0")]
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pub fn update_panic_count(amt: isize) -> usize {
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use cell::Cell;
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thread_local! { static PANIC_COUNT: Cell<usize> = Cell::new(0) }
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PANIC_COUNT.with(|c| {
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let next = (c.get() as isize + amt) as usize;
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c.set(next);
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return next
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})
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}
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// *Implementation borrowed from the libpanic_abort crate*
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//
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// Rust's "try" function, but if we're aborting on panics we just call the
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// function as there's nothing else we need to do here.
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#[allow(improper_ctypes)]
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extern fn __rust_maybe_catch_panic(f: fn(*mut u8),
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data: *mut u8,
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_data_ptr: *mut usize,
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_vtable_ptr: *mut usize) -> u32 {
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f(data);
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0
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}
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