From a7bccb20f87978ec7c49191d88cf51d51770f44d Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 18 Aug 2017 12:17:59 +0000
Subject: [PATCH] vm_insnhelper.c: raise ruby_error_sysstack_gc

* vm_insnhelper.c (rb_threadptr_stack_overflow): rb_fatal is not
  available during GC.  raise the preallocated fatal error.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59618 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 eval.c          | 1 +
 vm_core.h       | 1 +
 vm_insnhelper.c | 4 +++-
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/eval.c b/eval.c
index 2b6f7849fd..c94fbe4275 100644
--- a/eval.c
+++ b/eval.c
@@ -1930,6 +1930,7 @@ Init_eval(void)
     rb_define_global_function("untrace_var", rb_f_untrace_var, -1);	/* in variable.c */
 
     rb_vm_register_special_exception(ruby_error_reenter, rb_eFatal, "exception reentered");
+    rb_vm_register_special_exception(ruby_error_sysstack_gc, rb_eFatal, "machine stack overflow while GC is running.");
 
     id_signo = rb_intern_const("signo");
     id_status = rb_intern_const("status");
diff --git a/vm_core.h b/vm_core.h
index 5fc7b2b3ba..861cae0018 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -455,6 +455,7 @@ enum ruby_special_exceptions {
     ruby_error_reenter,
     ruby_error_nomemory,
     ruby_error_sysstack,
+    ruby_error_sysstack_gc,
     ruby_error_stream_closed,
     ruby_special_error_count
 };
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 303f9cc2fb..03b9d49e0e 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -57,7 +57,9 @@ void
 rb_threadptr_stack_overflow(rb_thread_t *th)
 {
     if (rb_during_gc()) {
-	rb_fatal("machine stack overflow while GC is running.");
+	th->ec.raised_flag = RAISED_STACKOVERFLOW;
+	th->ec.errinfo = th->vm->special_exceptions[ruby_error_sysstack_gc];
+	TH_JUMP_TAG(th, TAG_RAISE);
     }
 #ifdef USE_SIGALTSTACK
     threadptr_stack_overflow(th, TRUE);