// option. This file may not be copied, modified, or distributed
// except according to those terms.
+use error::Error;
use io;
-use io::prelude::*;
use libc;
-use mem;
-use sync::StaticMutex;
+use sys::backtrace::BacktraceContext;
+use sys_common::backtrace::Frame;
-use super::super::printing::print;
use unwind as uw;
-#[inline(never)] // if we know this is a function call, we can skip it when
- // tracing
-pub fn write(w: &mut Write) -> io::Result<()> {
- struct Context<'a> {
- idx: isize,
- writer: &'a mut (Write+'a),
- last_error: Option<io::Error>,
- }
+struct Context<'a> {
+ idx: usize,
+ frames: &'a mut [Frame],
+}
- // When using libbacktrace, we use some necessary global state, so we
- // need to prevent more than one thread from entering this block. This
- // is semi-reasonable in terms of printing anyway, and we know that all
- // I/O done here is blocking I/O, not green I/O, so we don't have to
- // worry about this being a native vs green mutex.
- static LOCK: StaticMutex = StaticMutex::new();
- let _g = LOCK.lock();
+#[derive(Debug)]
+struct UnwindError(uw::_Unwind_Reason_Code);
+
+impl Error for UnwindError {
+ fn description(&self) -> &'static str {
+ "unexpected return value while unwinding"
+ }
+}
- writeln!(w, "stack backtrace:")?;
+impl ::fmt::Display for UnwindError {
+ fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+ write!(f, "{}: {:?}", self.description(), self.0)
+ }
+}
- let mut cx = Context { writer: w, last_error: None, idx: 0 };
- return match unsafe {
+#[inline(never)] // if we know this is a function call, we can skip it when
+ // tracing
+pub fn unwind_backtrace(frames: &mut [Frame])
+ -> io::Result<(usize, BacktraceContext)>
+{
+ let mut cx = Context {
+ idx: 0,
+ frames: frames,
+ };
+ let result_unwind = unsafe {
uw::_Unwind_Backtrace(trace_fn,
- &mut cx as *mut Context as *mut libc::c_void)
- } {
- uw::_URC_NO_REASON => {
- match cx.last_error {
- Some(err) => Err(err),
- None => Ok(())
- }
- }
- _ => Ok(()),
+ &mut cx as *mut Context
+ as *mut libc::c_void)
};
-
- extern fn trace_fn(ctx: *mut uw::_Unwind_Context,
- arg: *mut libc::c_void) -> uw::_Unwind_Reason_Code {
- let cx: &mut Context = unsafe { mem::transmute(arg) };
- 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 {
- // this is a non-signaling frame, so `ip` refers to the address
- // after the calling instruction. account for that.
- ip = (ip as usize - 1) as *mut _;
+ // See libunwind:src/unwind/Backtrace.c for the return values.
+ // No, there is no doc.
+ match result_unwind {
+ // These return codes seem to be benign and need to be ignored for backtraces
+ // to show up properly on all tested platforms.
+ uw::_URC_END_OF_STACK | uw::_URC_FATAL_PHASE1_ERROR | uw::_URC_FAILURE => {
+ Ok((cx.idx, BacktraceContext))
}
-
- // dladdr() on osx gets whiny when we use FindEnclosingFunction, and
- // it appears to work fine without it, so we only use
- // FindEnclosingFunction on non-osx platforms. In doing so, we get a
- // slightly more accurate stack trace in the process.
- //
- // This is often because panic involves the last instruction of a
- // function being "call std::rt::begin_unwind", with no ret
- // instructions after it. This means that the return instruction
- // pointer points *outside* of the calling function, and by
- // unwinding it we go back to the original function.
- let symaddr = if cfg!(target_os = "macos") || cfg!(target_os = "ios") {
- ip
- } else {
- unsafe { uw::_Unwind_FindEnclosingFunction(ip) }
- };
-
- // Don't print out the first few frames (they're not user frames)
- cx.idx += 1;
- if cx.idx <= 0 { return uw::_URC_NO_REASON }
- // Don't print ginormous backtraces
- if cx.idx > 100 {
- match write!(cx.writer, " ... <frames omitted>\n") {
- Ok(()) => {}
- Err(e) => { cx.last_error = Some(e); }
- }
- return uw::_URC_FAILURE
+ _ => {
+ Err(io::Error::new(io::ErrorKind::Other,
+ UnwindError(result_unwind)))
}
+ }
+}
- // Once we hit an error, stop trying to print more frames
- if cx.last_error.is_some() { return uw::_URC_FAILURE }
+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) };
+ 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 {
+ // this is a non-signaling frame, so `ip` refers to the address
+ // after the calling instruction. account for that.
+ ip = (ip as usize - 1) as *mut _;
+ }
- match print(cx.writer, cx.idx, ip, symaddr) {
- Ok(()) => {}
- Err(e) => { cx.last_error = Some(e); }
- }
+ // dladdr() on osx gets whiny when we use FindEnclosingFunction, and
+ // it appears to work fine without it, so we only use
+ // FindEnclosingFunction on non-osx platforms. In doing so, we get a
+ // slightly more accurate stack trace in the process.
+ //
+ // This is often because panic involves the last instruction of a
+ // function being "call std::rt::begin_unwind", with no ret
+ // instructions after it. This means that the return instruction
+ // pointer points *outside* of the calling function, and by
+ // unwinding it we go back to the original function.
+ let symaddr = if cfg!(target_os = "macos") || cfg!(target_os = "ios") {
+ ip
+ } else {
+ unsafe { uw::_Unwind_FindEnclosingFunction(ip) }
+ };
- // keep going
- uw::_URC_NO_REASON
+ if cx.idx < cx.frames.len() {
+ cx.frames[cx.idx] = Frame {
+ symbol_addr: symaddr,
+ exact_position: ip,
+ };
+ cx.idx += 1;
}
+
+ uw::_URC_NO_REASON
}
projects / rust.git / blobdiff