1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
use error::Error;
use io;
use libc;
use sys::backtrace::BacktraceContext;
use sys_common::backtrace::Frame;
use unwind as uw;
struct Context<'a> {
    idx: usize,
    frames: &'a mut [Frame],
}
#[derive(Debug)]
struct UnwindError(uw::_Unwind_Reason_Code);
impl Error for UnwindError {
    fn description(&self) -> &'static str {
        "unexpected return value while unwinding"
    }
}
impl ::fmt::Display for UnwindError {
    fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
        write!(f, "{}: {:?}", self.description(), self.0)
    }
}
#[inline(never)] 
                 
pub fn unwind_backtrace(frames: &mut [Frame])
    -> io::Result<(usize, BacktraceContext)>
{
    let mut cx = Context {
        idx: 0,
        frames,
    };
    let result_unwind = unsafe {
        uw::_Unwind_Backtrace(trace_fn,
                              &mut cx as *mut Context
                              as *mut libc::c_void)
    };
    
    
    match result_unwind {
        
        
        uw::_URC_END_OF_STACK | uw::_URC_FATAL_PHASE1_ERROR | uw::_URC_FAILURE => {
            Ok((cx.idx, BacktraceContext))
        }
        _ => {
            Err(io::Error::new(io::ErrorKind::Other,
                               UnwindError(result_unwind)))
        }
    }
}
extern fn trace_fn(ctx: *mut uw::_Unwind_Context,
                   arg: *mut libc::c_void) -> uw::_Unwind_Reason_Code {
    let cx = unsafe { &mut *(arg as *mut Context) };
    if cx.idx >= cx.frames.len() {
        return uw::_URC_NORMAL_STOP;
    }
    let mut ip_before_insn = 0;
    let mut ip = unsafe {
        uw::_Unwind_GetIPInfo(ctx, &mut ip_before_insn) as *mut libc::c_void
    };
    if !ip.is_null() && ip_before_insn == 0 {
        
        
        ip = (ip as usize - 1) as *mut _;
    }
    
    
    
    
    
    
    
    
    
    
    let symaddr = if cfg!(target_os = "macos") || cfg!(target_os = "ios") {
        ip
    } else {
        unsafe { uw::_Unwind_FindEnclosingFunction(ip) }
    };
    cx.frames[cx.idx] = Frame {
        symbol_addr: symaddr as *mut u8,
        exact_position: ip as *mut u8,
        inline_context: 0,
    };
    cx.idx += 1;
    uw::_URC_NO_REASON
}