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// Copyright 2014-2015 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.
/// As always - iOS on arm uses SjLj exceptions and
/// _Unwind_Backtrace is even not available there. Still,
/// backtraces could be extracted using a backtrace function,
/// which thanks god is public
///
/// As mentioned in a huge comment block in `super::super`, backtrace
/// doesn't play well with green threads, so while it is extremely nice and
/// simple to use it should be used only on iOS devices as the only viable
/// option.
use io::prelude::*;
use io;
use libc;
use mem;
use sys::mutex::Mutex;
use super::super::printing::print;
#[inline(never)]
pub fn write(w: &mut Write) -> io::Result<()> {
extern {
fn backtrace(buf: *mut *mut libc::c_void,
sz: libc::c_int) -> libc::c_int;
}
// while it doesn't requires lock for work as everything is
// local, it still displays much nicer backtraces when a
// couple of threads panic simultaneously
static LOCK: Mutex = Mutex::new();
unsafe {
LOCK.lock();
writeln!(w, "stack backtrace:")?;
// 100 lines should be enough
const SIZE: usize = 100;
let mut buf: [*mut libc::c_void; SIZE] = mem::zeroed();
let cnt = backtrace(buf.as_mut_ptr(), SIZE as libc::c_int) as usize;
// skipping the first one as it is write itself
for i in 1..cnt {
print(w, i as isize, buf[i], buf[i])?
}
LOCK.unlock();
}
Ok(())
}
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