merge revision(s) 64589,64593: [Backport #15041]

	cont.c: set th->root_fiber to current fiber at fork

	Otherwise, th->root_fiber can point to an invalid Fiber,
	because Fibers do not live across fork.  So consider
	whatever Fiber is running the root fiber.

	[ruby-core:88723] [Bug #15041]

	cont.c (rb_fiber_atfork): th->root_fiber may not exist

	Otherwise, bootstraptest/test_fork.rb fails with -DVM_CHECK_MODE=2

	[Bug #15041]

	Fixes: r64589 "cont.c: set th->root_fiber to current fiber at fork"

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@66818 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

cont.c

@@ -1932,6 +1932,20 @@ fiber_to_s(VALUE fibval)
     return rb_block_to_s(fibval, &proc->block, status_info);
 }
 
+#ifdef HAVE_WORKING_FORK
+void
+rb_fiber_atfork(rb_thread_t *th)
+{
+    if (th->root_fiber) {
+        if (&th->root_fiber->cont.saved_ec != th->ec) {
+            th->root_fiber = th->ec->fiber_ptr;
+            th->root_fiber->cont.type = ROOT_FIBER_CONTEXT;
+        }
+        th->root_fiber->prev = 0;
+    }
+}
+#endif
+
 /*
  *  Document-class: FiberError
  *

test/ruby/test_fiber.rb

@@ -269,7 +269,11 @@ def test_fork_from_fiber
     end
     bug5700 = '[ruby-core:41456]'
     assert_nothing_raised(bug5700) do
-      Fiber.new{ pid = fork {} }.resume
+      Fiber.new do
+        pid = fork do
+          Fiber.new {}.transfer
+        end
+      end.resume
     end
     pid, status = Process.waitpid2(pid)
     assert_equal(0, status.exitstatus, bug5700)

thread.c

@@ -4231,13 +4231,15 @@ terminate_atfork_i(rb_thread_t *th, const rb_thread_t *current_th)
     }
 }
 
+void rb_fiber_atfork(rb_thread_t *);
 void
 rb_thread_atfork(void)
 {
     rb_thread_t *th = GET_THREAD();
     rb_thread_atfork_internal(th, terminate_atfork_i);
     th->join_list = NULL;
     rb_mutex_cleanup_keeping_mutexes(th);
+    rb_fiber_atfork(th);
 
     /* We don't want reproduce CVE-2003-0900. */
     rb_reset_random_seed();

version.h

@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.5.4"
-#define RUBY_RELEASE_DATE "2019-01-11"
-#define RUBY_PATCHLEVEL 128
+#define RUBY_RELEASE_DATE "2019-01-14"
+#define RUBY_PATCHLEVEL 129
 
 #define RUBY_RELEASE_YEAR 2019
 #define RUBY_RELEASE_MONTH 1
-#define RUBY_RELEASE_DAY 11
+#define RUBY_RELEASE_DAY 14
 
 #include "ruby/version.h"