From 08e6389d6e3e027fd8821ce63bda52821d68bec6 Mon Sep 17 00:00:00 2001
From: Suraj N. Kurapati <sunaku@gmail.com>
Date: Sat, 24 Oct 2009 20:55:11 -0700
Subject: [PATCH 2/2] * include/ruby/ruby.h: declare ruby_bind_stack(). [ruby-core:26361]

* gc.c: implement ruby_bind_stack().  restrict GC marking
  region to ruby_bind_stack() boundaries for main thread.
---
 ChangeLog           |    7 +++++++
 gc.c                |   22 ++++++++++++++++++++++
 include/ruby/ruby.h |    6 ++++++
 3 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 01fae7a..980c729 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -313,6 +313,13 @@ Sun Oct 25 13:33:58 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 Mon Oct 25 13:28:00 2009  Suraj N. Kurapati <sunaku@gmail.com>
 
+	* include/ruby/ruby.h: declare ruby_bind_stack(). [ruby-core:26361]
+
+	* gc.c: implement ruby_bind_stack().  restrict GC marking
+	  region to ruby_bind_stack() boundaries for main thread.
+
+Mon Oct 25 13:28:00 2009  Suraj N. Kurapati <sunaku@gmail.com>
+
 	* gc.c: refactor common code from mark_current_machine_context()
 	  and rb_gc_mark_machine_stack() into get_machine_stack_bounds().
 
diff --git a/gc.c b/gc.c
index 0b588dc..4f47267 100644
--- a/gc.c
+++ b/gc.c
@@ -19,6 +19,7 @@
 #include "eval_intern.h"
 #include "vm_core.h"
 #include "gc.h"
+#include <assert.h>
 #include <stdio.h>
 #include <setjmp.h>
 #include <sys/types.h>
@@ -2089,6 +2090,17 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
 
 void rb_vm_mark(void *ptr);
 
+static VALUE *ruby_stack_lower_bound = 0,
+             *ruby_stack_upper_bound = 0;
+
+void
+ruby_bind_stack(void *lower, void *upper)
+{
+    assert(upper > lower);
+    ruby_stack_lower_bound = lower;
+    ruby_stack_upper_bound = upper;
+}
+
 static void
 get_machine_stack_bounds(rb_thread_t *th, VALUE **stack_start, VALUE **stack_end, unsigned stack_end_increment)
 {
@@ -2108,6 +2120,16 @@ get_machine_stack_bounds(rb_thread_t *th, VALUE **stack_start, VALUE **stack_end
         *stack_end = th->machine_stack_end + stack_end_increment;
     }
 #endif
+
+    if (th == th->vm->main_thread) {
+        if (ruby_stack_lower_bound && *stack_start < ruby_stack_lower_bound) {
+          *stack_start = ruby_stack_lower_bound;
+        }
+
+        if (ruby_stack_upper_bound && *stack_end > ruby_stack_upper_bound) {
+          *stack_end = ruby_stack_upper_bound;
+        }
+    }
 }
 
 static void
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 55836a8..957b953 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1143,6 +1143,12 @@ void ruby_init_stack(volatile VALUE*);
 #define RUBY_INIT_STACK \
     VALUE variable_in_this_stack_frame; \
     ruby_init_stack(&variable_in_this_stack_frame);
+/*
+ * Binds Ruby's stack to the region of memory that spans from the given
+ * "lower" boundary up to (but not including) the given "upper" boundary.
+ * Note that these boundaries _do not_ protect against stack overflow!
+ */
+void ruby_bind_stack(void *lower, void *upper);
 void ruby_init(void);
 void *ruby_options(int, char**);
 int ruby_run_node(void *);
-- 
1.6.5.1