merges r20372-r20375 and r20380 from trunk into ruby_1_9_1.

* signal.c (register_sigaltstack): minimum size is insufficient for
  method calls.

* signal.c (sigsegv): handles stack overflow if possible.

* thread.c (ruby_thread_stack_overflow): helper function to raise
  sysstack_error.

* thread_pthread.c (ruby_stack_overflowed_p): checks for stack
  overflow.

* signal.c (ruby_sigaction_t): added.

* signal.c (register_sigaltstack): stores alt stack for debug
  purpose.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@20422 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 3 deletions

diff --git a/gc.c b/gc.c
index e1878de3ba..2f194ddf74 100644
--- a/gc.c
+++ b/gc.c
@@ -1047,8 +1047,8 @@ ruby_stack_length(VALUE **p)
     return STACK_LENGTH;
 }
 
-int
-ruby_stack_check(void)
+static int
+stack_check(void)
 {
     int ret;
     rb_thread_t *th = GET_THREAD();
@@ -1063,6 +1063,16 @@ ruby_stack_check(void)
     return ret;
 }
 
+int
+ruby_stack_check(void)
+{
+#if defined(POSIX_SIGNAL) && defined(SIGSEGV) && defined(HAVE_SIGALTSTACK)
+    return 0;
+#else
+    return stack_check();
+#endif
+}
+
 static void
 init_mark_stack(rb_objspace_t *objspace)
 {
@@ -1269,7 +1279,7 @@ gc_mark(rb_objspace_t *objspace, VALUE ptr, int lev)
     if (obj->as.basic.flags & FL_MARK) return;  /* already marked */
     obj->as.basic.flags |= FL_MARK;
 
-    if (lev > GC_LEVEL_MAX || (lev == 0 && ruby_stack_check())) {
+    if (lev > GC_LEVEL_MAX || (lev == 0 && stack_check())) {
 	if (!mark_stack_overflow) {
 	    if (mark_stack_ptr - mark_stack < MARK_STACK_MAX) {
 		*mark_stack_ptr = ptr;