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use crate::error::Error;
use crate::fmt;
use crate::io;
use crate::sys::backtrace::BacktraceContext;
use crate::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
}