From b4d8d2638cb06f60d3c45653f5e6054940b84b8d Mon Sep 17 00:00:00 2001
From: Martin Quinson <martin.quinson@ens-rennes.fr>
Date: Mon, 7 Oct 2019 00:28:34 +0200
Subject: [PATCH] Also attach our signal handler to SIGBUS, because MacOSX
 sometimes raises it on stack overflow

---
 src/simix/smx_global.cpp                      | 46 ++++++++++---------
 .../simix/stack-overflow/stack-overflow.tesh  |  2 +-
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/src/simix/smx_global.cpp b/src/simix/smx_global.cpp
index 4028e9a21a..7414de1529 100644
--- a/src/simix/smx_global.cpp
+++ b/src/simix/smx_global.cpp
@@ -54,19 +54,20 @@ XBT_ATTRIB_NORETURN static void inthandler(int)
 #ifndef _WIN32
 static void segvhandler(int signum, siginfo_t* siginfo, void* /*context*/)
 {
-  if (siginfo->si_signo == SIGSEGV && siginfo->si_code == SEGV_ACCERR) {
-    fprintf(stderr, "Access violation detected.\n"
-                    "This probably comes from a programming error in your code, or from a stack\n"
-                    "overflow. If you are certain of your code, try increasing the stack size\n"
-                    "   --cfg=contexts/stack-size=XXX (current size is %u KiB).\n"
-                    "\n"
-                    "If it does not help, this may have one of the following causes:\n"
-                    "a bug in SimGrid, a bug in the OS or a bug in a third-party libraries.\n"
-                    "Failing hardware can sometimes generate such errors too.\n"
-                    "\n"
-                    "If you think you've found a bug in SimGrid, please report it along with a\n"
-                    "Minimal Working Example (MWE) reproducing your problem and a full backtrace\n"
-                    "of the fault captured with gdb or valgrind.\n",
+  if ((siginfo->si_signo == SIGSEGV && siginfo->si_code == SEGV_ACCERR) || siginfo->si_signo == SIGBUS) {
+    fprintf(stderr,
+            "Access violation or Bus error detected.\n"
+            "This probably comes from a programming error in your code, or from a stack\n"
+            "overflow. If you are certain of your code, try increasing the stack size\n"
+            "   --cfg=contexts/stack-size=XXX (current size is %u KiB).\n"
+            "\n"
+            "If it does not help, this may have one of the following causes:\n"
+            "a bug in SimGrid, a bug in the OS or a bug in a third-party libraries.\n"
+            "Failing hardware can sometimes generate such errors too.\n"
+            "\n"
+            "If you think you've found a bug in SimGrid, please report it along with a\n"
+            "Minimal Working Example (MWE) reproducing your problem and a full backtrace\n"
+            "of the fault captured with gdb or valgrind.\n",
             smx_context_stack_size / 1024);
   } else  if (siginfo->si_signo == SIGSEGV) {
     fprintf(stderr, "Segmentation fault.\n");
@@ -113,14 +114,17 @@ static void install_segvhandler()
   action.sa_flags = SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
   sigemptyset(&action.sa_mask);
 
-  if (sigaction(SIGSEGV, &action, &old_action) == -1) {
-    XBT_WARN("Failed to register signal handler for SIGSEGV: %s", strerror(errno));
-    return;
-  }
-  if ((old_action.sa_flags & SA_SIGINFO) || old_action.sa_handler != SIG_DFL) {
-    XBT_DEBUG("A signal handler was already installed for SIGSEGV (%p). Restore it.",
-             (old_action.sa_flags & SA_SIGINFO) ? (void*)old_action.sa_sigaction : (void*)old_action.sa_handler);
-    sigaction(SIGSEGV, &old_action, nullptr);
+  /* Linux tend to raise only SIGSEGV where other systems also raise SIGBUS on severe error */
+  for (int sig : {SIGSEGV, SIGBUS}) {
+    if (sigaction(sig, &action, &old_action) == -1) {
+      XBT_WARN("Failed to register signal handler for signal %d: %s", sig, strerror(errno));
+      continue;
+    }
+    if ((old_action.sa_flags & SA_SIGINFO) || old_action.sa_handler != SIG_DFL) {
+      XBT_DEBUG("A signal handler was already installed for signal %d (%p). Restore it.", sig,
+                (old_action.sa_flags & SA_SIGINFO) ? (void*)old_action.sa_sigaction : (void*)old_action.sa_handler);
+      sigaction(sig, &old_action, nullptr);
+    }
   }
 }
 
diff --git a/teshsuite/simix/stack-overflow/stack-overflow.tesh b/teshsuite/simix/stack-overflow/stack-overflow.tesh
index c7180faaed..11c9899b7d 100644
--- a/teshsuite/simix/stack-overflow/stack-overflow.tesh
+++ b/teshsuite/simix/stack-overflow/stack-overflow.tesh
@@ -1,7 +1,7 @@
 ! expect signal SIGSEGV
 $ ${bindir:=.}/stack-overflow --cfg=contexts/stack-size:96 ${srcdir:=.}/examples/platforms/small_platform.xml
 > [Tremblay:master:(1) 0.000000] [test/INFO] Launching our nice bugged recursive function...
-> Access violation detected.
+> Access violation or Bus error detected.
 > This probably comes from a programming error in your code, or from a stack
 > overflow. If you are certain of your code, try increasing the stack size
 >    --cfg=contexts/stack-size=XXX (current size is 96 KiB).
-- 
2.20.1