1 files changed, 121 insertions, 0 deletions
diff --git a/src/libstd/sys/cloudabi/backtrace.rs b/src/libstd/sys/cloudabi/backtrace.rs
new file mode 100644
index 00000000000..33d93179237
--- /dev/null
+++ b/src/libstd/sys/cloudabi/backtrace.rs
@@ -0,0 +1,121 @@
+// Copyright 2014-2018 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 error::Error;
+use ffi::CStr;
+use intrinsics;
+use io;
+use libc;
+use sys_common::backtrace::Frame;
+use unwind as uw;
+
+pub struct BacktraceContext;
+
+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)] // 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 };
+    let result_unwind =
+        unsafe { uw::_Unwind_Backtrace(trace_fn, &mut cx as *mut Context as *mut libc::c_void) };
+    // 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))
+        }
+        _ => Err(io::Error::new(
+            io::ErrorKind::Other,
+            UnwindError(result_unwind),
+        )),
+    }
+}
+
+extern "C" 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 _;
+    }
+
+    let symaddr = unsafe { uw::_Unwind_FindEnclosingFunction(ip) };
+    if cx.idx < cx.frames.len() {
+        cx.frames[cx.idx] = Frame {
+            symbol_addr: symaddr as *mut u8,
+            exact_position: ip as *mut u8,
+        };
+        cx.idx += 1;
+    }
+
+    uw::_URC_NO_REASON
+}
+
+pub fn foreach_symbol_fileline<F>(_: Frame, _: F, _: &BacktraceContext) -> io::Result<bool>
+where
+    F: FnMut(&[u8], u32) -> io::Result<()>,
+{
+    // No way to obtain this information on CloudABI.
+    Ok(false)
+}
+
+pub fn resolve_symname<F>(frame: Frame, callback: F, _: &BacktraceContext) -> io::Result<()>
+where
+    F: FnOnce(Option<&str>) -> io::Result<()>,
+{
+    unsafe {
+        let mut info: Dl_info = intrinsics::init();
+        let symname =
+            if dladdr(frame.exact_position as *mut _, &mut info) == 0 || info.dli_sname.is_null() {
+                None
+            } else {
+                CStr::from_ptr(info.dli_sname).to_str().ok()
+            };
+        callback(symname)
+    }
+}
+
+#[repr(C)]
+struct Dl_info {
+    dli_fname: *const libc::c_char,
+    dli_fbase: *mut libc::c_void,
+    dli_sname: *const libc::c_char,
+    dli_saddr: *mut libc::c_void,
+}
+
+extern "C" {
+    fn dladdr(addr: *const libc::c_void, info: *mut Dl_info) -> libc::c_int;
+}