rust/src/libstd/failure.rs
2014-06-15 23:30:24 -07:00

103 lines
3.6 KiB
Rust

// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use alloc::owned::Box;
use any::{Any, AnyRefExt};
use fmt;
use io::{Writer, IoResult};
use kinds::Send;
use option::{Some, None};
use result::Ok;
use rt::backtrace;
use rt::{Stderr, Stdio};
use rustrt::local::Local;
use rustrt::task::Task;
use str::Str;
use string::String;
// Defined in this module instead of io::stdio so that the unwinding
local_data_key!(pub local_stderr: Box<Writer + Send>)
impl Writer for Stdio {
fn write(&mut self, bytes: &[u8]) -> IoResult<()> {
fn fmt_write<F: fmt::FormatWriter>(f: &mut F, bytes: &[u8]) {
let _ = f.write(bytes);
}
fmt_write(self, bytes);
Ok(())
}
}
pub fn on_fail(obj: &Any + Send, file: &'static str, line: uint) {
let msg = match obj.as_ref::<&'static str>() {
Some(s) => *s,
None => match obj.as_ref::<String>() {
Some(s) => s.as_slice(),
None => "Box<Any>",
}
};
let mut err = Stderr;
// It is assumed that all reasonable rust code will have a local task at
// all times. This means that this `exists` will return true almost all of
// the time. There are border cases, however, when the runtime has
// *almost* set up the local task, but hasn't quite gotten there yet. In
// order to get some better diagnostics, we print on failure and
// immediately abort the whole process if there is no local task
// available.
if !Local::exists(None::<Task>) {
let _ = writeln!(&mut err, "failed at '{}', {}:{}", msg, file, line);
if backtrace::log_enabled() {
let _ = backtrace::write(&mut err);
} else {
let _ = writeln!(&mut err, "run with `RUST_BACKTRACE=1` to \
see a backtrace");
}
return
}
// Peel the name out of local task so we can print it. We've got to be sure
// that the local task is in TLS while we're printing as I/O may occur.
let (name, unwinding) = {
let mut t = Local::borrow(None::<Task>);
(t.name.take(), t.unwinder.unwinding())
};
{
let n = name.as_ref().map(|n| n.as_slice()).unwrap_or("<unnamed>");
match local_stderr.replace(None) {
Some(mut stderr) => {
// FIXME: what to do when the task printing fails?
let _ = writeln!(stderr,
"task '{}' failed at '{}', {}:{}\n",
n, msg, file, line);
if backtrace::log_enabled() {
let _ = backtrace::write(stderr);
}
local_stderr.replace(Some(stderr));
}
None => {
let _ = writeln!(&mut err, "task '{}' failed at '{}', {}:{}",
n, msg, file, line);
if backtrace::log_enabled() {
let _ = backtrace::write(&mut err);
}
}
}
// If this is a double failure, make sure that we printed a backtrace
// for this failure.
if unwinding && !backtrace::log_enabled() {
let _ = backtrace::write(&mut err);
}
}
Local::borrow(None::<Task>).name = name;
}