* signal.c (set_sig_handler): Set up and tear down alternate

stack for SIGBUS also, not only for SIGSEGV. On Linux,
when stack growth collides with another memory mapping,
it triggers a SIGBUS not SIGSEGV, which occurs when the
process limit on stack size is exceeded. In either
situation, we need an alternative stack.

2 files changed, 11 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 90346146..c986a5d5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2014-07-20  Kaz Kylheku  <kaz@kylheku.com>
 
+	* signal.c (set_sig_handler): Set up and tear down alternate
+	stack for SIGBUS also, not only for SIGSEGV. On Linux,
+	when stack growth collides with another memory mapping,
+	it triggers a SIGBUS not SIGSEGV, which occurs when the
+	process limit on stack size is exceeded. In either
+	situation, we need an alternative stack.
+
+2014-07-20  Kaz Kylheku  <kaz@kylheku.com>
+
 	* eval.c (caseq_s, caseql_s, casequal_s, memq_s, memql_s, memqual_s,
 	eq_s, eql_s, equal_s): New symbol variables.
 	(me_case): New static function.
diff --git a/signal.c b/signal.c
index 086b0031..5072f09d 100644
--- a/signal.c
+++ b/signal.c
@@ -236,7 +236,7 @@ val set_sig_handler(val signo, val lambda)
       sa.sa_handler = sig_handler;
       sigfillset(&sa.sa_mask);
 #if HAVE_SIGALTSTACK
-      if (sig == SIGSEGV)
+      if (sig == SIGSEGV || sig == SIGBUS)
         setup_alt_stack();
       sa.sa_flags |= SA_ONSTACK;
 #endif
@@ -244,7 +244,7 @@ val set_sig_handler(val signo, val lambda)
     }
 
 #if HAVE_SIGALTSTACK
-    if (sig == SIGSEGV && (lambda == nil || lambda == t))
+    if ((sig == SIGSEGV || sig == SIGBUS) && (lambda == nil || lambda == t))
         teardown_alt_stack();
 #endif