Add Fiber's double resume test and fix it.

include/mruby.h

@@ -70,7 +70,7 @@ typedef struct {
 enum mrb_fiber_state {
   MRB_FIBER_CREATED = 0,
   MRB_FIBER_RUNNING,
-  MRB_FIBER_RESUMED,
+  MRB_FIBER_SUSPENDED,
   MRB_FIBER_TERMINATED,
 };
 

mrbgems/mruby-fiber/src/fiber.c

@@ -161,14 +161,13 @@ fiber_resume(mrb_state *mrb, mrb_value self)
       mrb_raise(mrb, E_ARGUMENT_ERROR, "can't cross C function boundary");
     }
   }
-  if (c->status == MRB_FIBER_RESUMED) {
+  if (c->status == MRB_FIBER_RUNNING) {
     mrb_raise(mrb, E_RUNTIME_ERROR, "double resume");
   }
   if (c->status == MRB_FIBER_TERMINATED) {
     mrb_raise(mrb, E_RUNTIME_ERROR, "resuming dead fiber");
   }
   mrb_get_args(mrb, "*", &a, &len);
-  mrb->c->status = MRB_FIBER_RESUMED;
   if (c->status == MRB_FIBER_CREATED) {
     mrb_value *b = c->stack+1;
     mrb_value *e = b + len;
@@ -181,6 +180,7 @@ fiber_resume(mrb_state *mrb, mrb_value self)
     if (c->prev->fib) 
       mrb_field_write_barrier(mrb, (struct RBasic*)c->fib, (struct RBasic*)c->prev->fib);
     mrb_write_barrier(mrb, (struct RBasic*)c->fib);
+    mrb->c->status = MRB_FIBER_SUSPENDED;
     c->status = MRB_FIBER_RUNNING;
     mrb->c = c;
 
@@ -192,6 +192,7 @@ fiber_resume(mrb_state *mrb, mrb_value self)
   if (c->prev->fib) 
     mrb_field_write_barrier(mrb, (struct RBasic*)c->fib, (struct RBasic*)c->prev->fib);
   mrb_write_barrier(mrb, (struct RBasic*)c->fib);
+  mrb->c->status = MRB_FIBER_SUSPENDED;
   c->status = MRB_FIBER_RUNNING;
   mrb->c = c;
   return fiber_result(mrb, a, len);
@@ -227,6 +228,7 @@ mrb_fiber_yield(mrb_state *mrb, int len, mrb_value *a)
   }
 
   c->prev->status = MRB_FIBER_RUNNING;
+  c->status = MRB_FIBER_SUSPENDED;
   mrb->c = c->prev;
   c->prev = NULL;
   MARK_CONTEXT_MODIFY(mrb->c);

mrbgems/mruby-fiber/test/fiber.rb

@@ -62,3 +62,16 @@ assert('Yield raises when called on root fiber') {
     true
   end
 }
+
+assert('Double resume of Fiber') do
+  f1 = Fiber.new {}
+  f2 = Fiber.new {
+    f1.resume
+    assert_raise(RuntimeError) { f2.resume }
+    Fiber.yield 0
+  }
+  assert_equal 0, f2.resume
+  f2.resume
+  assert_false f1.alive?
+  assert_false f2.alive?
+end