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use prelude::v1::*;
use io::prelude::*;
use any::Any;
use cell::Cell;
use cell::RefCell;
use intrinsics;
use sync::StaticRwLock;
use sys::stdio::Stderr;
use sys_common::backtrace;
use sys_common::thread_info;
use sys_common::util;
use thread;
thread_local! { pub static PANIC_COUNT: Cell<usize> = Cell::new(0) }
thread_local! {
pub static LOCAL_STDERR: RefCell<Option<Box<Write + Send>>> = {
RefCell::new(None)
}
}
#[derive(Copy, Clone)]
enum Handler {
Default,
Custom(*mut (Fn(&PanicInfo) + 'static + Sync + Send)),
}
static HANDLER_LOCK: StaticRwLock = StaticRwLock::new();
static mut HANDLER: Handler = Handler::Default;
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn set_handler<F>(handler: F) where F: Fn(&PanicInfo) + 'static + Sync + Send {
if thread::panicking() {
panic!("cannot modify the panic handler from a panicking thread");
}
let handler = Box::new(handler);
unsafe {
let lock = HANDLER_LOCK.write();
let old_handler = HANDLER;
HANDLER = Handler::Custom(Box::into_raw(handler));
drop(lock);
if let Handler::Custom(ptr) = old_handler {
Box::from_raw(ptr);
}
}
}
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn take_handler() -> Box<Fn(&PanicInfo) + 'static + Sync + Send> {
if thread::panicking() {
panic!("cannot modify the panic handler from a panicking thread");
}
unsafe {
let lock = HANDLER_LOCK.write();
let handler = HANDLER;
HANDLER = Handler::Default;
drop(lock);
match handler {
Handler::Default => Box::new(default_handler),
Handler::Custom(ptr) => {Box::from_raw(ptr)}
}
}
}
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub struct PanicInfo<'a> {
payload: &'a (Any + Send),
location: Location<'a>,
}
impl<'a> PanicInfo<'a> {
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn payload(&self) -> &(Any + Send) {
self.payload
}
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn location(&self) -> Option<&Location> {
Some(&self.location)
}
}
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub struct Location<'a> {
file: &'a str,
line: u32,
}
impl<'a> Location<'a> {
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn file(&self) -> &str {
self.file
}
#[unstable(feature = "panic_handler", reason = "awaiting feedback", issue = "30449")]
pub fn line(&self) -> u32 {
self.line
}
}
fn default_handler(info: &PanicInfo) {
let panics = PANIC_COUNT.with(|s| s.get());
let log_backtrace = panics >= 2 || backtrace::log_enabled();
let file = info.location.file;
let line = info.location.line;
let msg = match info.payload.downcast_ref::<&'static str>() {
Some(s) => *s,
None => match info.payload.downcast_ref::<String>() {
Some(s) => &s[..],
None => "Box<Any>",
}
};
let mut err = Stderr::new().ok();
let thread = thread_info::current_thread();
let name = thread.as_ref().and_then(|t| t.name()).unwrap_or("<unnamed>");
let write = |err: &mut ::io::Write| {
let _ = writeln!(err, "thread '{}' panicked at '{}', {}:{}",
name, msg, file, line);
if log_backtrace {
let _ = backtrace::write(err);
}
};
let prev = LOCAL_STDERR.with(|s| s.borrow_mut().take());
match (prev, err.as_mut()) {
(Some(mut stderr), _) => {
write(&mut *stderr);
let mut s = Some(stderr);
LOCAL_STDERR.with(|slot| {
*slot.borrow_mut() = s.take();
});
}
(None, Some(ref mut err)) => { write(err) }
_ => {}
}
}
pub fn on_panic(obj: &(Any+Send), file: &'static str, line: u32) {
let panics = PANIC_COUNT.with(|s| {
let count = s.get() + 1;
s.set(count);
count
});
if panics >= 3 {
util::dumb_print(format_args!("thread panicked while processing \
panic. aborting.\n"));
unsafe { intrinsics::abort() }
}
let info = PanicInfo {
payload: obj,
location: Location {
file: file,
line: line,
},
};
unsafe {
let _lock = HANDLER_LOCK.read();
match HANDLER {
Handler::Default => default_handler(&info),
Handler::Custom(ptr) => (*ptr)(&info),
}
}
if panics >= 2 {
util::dumb_print(format_args!("thread panicked while panicking. \
aborting.\n"));
unsafe { intrinsics::abort() }
}
}