From 09ae311009060c8bf6cda09873b78f81b268badd Mon Sep 17 00:00:00 2001
From: Gabriel Corona <gabriel.corona@loria.fr>
Date: Fri, 22 Jul 2016 15:56:29 +0200
Subject: [PATCH] [xbt] Install a custom exception handler

It shows the current backtrace and the exception context (if any):
backtrace, simulated process PID, etc.
---
 include/xbt/log.h     |  2 ++
 include/xbt/log.hpp   |  2 ++
 src/xbt/exception.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++
 src/xbt/xbt_main.c    |  2 ++
 4 files changed, 68 insertions(+)

diff --git a/include/xbt/log.h b/include/xbt/log.h
index 4c24f32120..837829f1ab 100644
--- a/include/xbt/log.h
+++ b/include/xbt/log.h
@@ -659,5 +659,7 @@ extern xbt_log_layout_t xbt_log_default_layout;
  */
 #define XBT_HERE(...) XBT_LOG(xbt_log_priority_trace, "-- was here" __VA_ARGS__)
 
+XBT_PUBLIC(void) xbt_set_terminate();
+
 SG_END_DECL()
 #endif                          /* ! _XBT_LOG_H_ */
diff --git a/include/xbt/log.hpp b/include/xbt/log.hpp
index 875b3ad714..6dbf711f5f 100644
--- a/include/xbt/log.hpp
+++ b/include/xbt/log.hpp
@@ -20,5 +20,7 @@ XBT_PUBLIC(void) logException(
   e_xbt_log_priority_t priority,
   const char* context, std::exception const& exception);
 
+XBT_PUBLIC(void) installExceptionHandler();
+
 }
 }
diff --git a/src/xbt/exception.cpp b/src/xbt/exception.cpp
index 6e9cf0c258..49f6188893 100644
--- a/src/xbt/exception.cpp
+++ b/src/xbt/exception.cpp
@@ -7,6 +7,7 @@
 #include <exception>
 #include <typeinfo>
 #include <memory>
+#include <mutex>
 
 #include <xbt/backtrace.hpp>
 #include <xbt/exception.hpp>
@@ -68,5 +69,66 @@ void logException(
   }
 }
 
+static void showBacktrace(std::vector<xbt_backtrace_location_t>& bt)
+{
+  std::vector<std::string> res = resolveBacktrace(&bt[0], bt.size());
+  XBT_LOG(xbt_log_priority_critical, "Current backtrace:");
+  for (std::string const& s : res)
+    XBT_LOG(xbt_log_priority_critical, "  -> %s", s.c_str());
+}
+
+static std::terminate_handler previous_terminate_handler = nullptr;
+
+static void handler()
+{
+  // Avoid doing crazy things if we get an uncaught exception inside
+  // an uncaught exception
+  static std::atomic_flag lock = ATOMIC_FLAG_INIT;
+  if (lock.test_and_set()) {
+    XBT_ERROR("Multiple uncaught exceptions");
+    std::abort();
+  }
+
+  // Get the current backtrace and exception
+  auto e = std::current_exception();
+  auto bt = backtrace();
+  try {
+    std::rethrow_exception(e);
+  }
+
+  // We manage C++ exception ourselves
+  catch (std::exception& e) {
+    logException(xbt_log_priority_critical, "Uncaught exception", e);
+    showBacktrace(bt);
+    std::abort();
+  }
+
+  // We don't know how to manage other exceptions
+  catch (...) {
+    // If there was another handler let's delegate to it
+    if (previous_terminate_handler)
+      previous_terminate_handler();
+    else {
+      XBT_ERROR("Unknown uncaught exception");
+      showBacktrace(bt);
+      std::abort();
+    }
+  }
+
+}
+
+void installExceptionHandler()
+{
+  static std::once_flag handler_flag;
+  std::call_once(handler_flag, [] {
+    previous_terminate_handler = std::set_terminate(handler);
+  });
+}
+
 }
 }
+
+void xbt_set_terminate()
+{
+  simgrid::xbt::installExceptionHandler();
+}
diff --git a/src/xbt/xbt_main.c b/src/xbt/xbt_main.c
index 3451b60527..13ec9e30b5 100644
--- a/src/xbt/xbt_main.c
+++ b/src/xbt/xbt_main.c
@@ -137,6 +137,8 @@ static void xbt_postexit(void)
 /** @brief Initialize the xbt mechanisms. */
 void xbt_init(int *argc, char **argv)
 {
+  xbt_set_terminate();
+
   if (xbt_initialized++) {
     XBT_DEBUG("XBT was initialized %d times.", xbt_initialized);
     return;
-- 
2.20.1