diff options
| -rw-r--r-- | scheduler.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/scheduler.c b/scheduler.c index bb406a5cf6..edb38b666c 100644 --- a/scheduler.c +++ b/scheduler.c @@ -412,7 +412,15 @@ rb_fiber_scheduler_unblock(VALUE scheduler, VALUE blocker, VALUE fiber) { RUBY_ASSERT(rb_obj_is_fiber(fiber)); - return rb_funcall(scheduler, id_unblock, 2, blocker, fiber); + // `rb_fiber_scheduler_unblock` can be called from points where `errno` is expected to be preserved. Therefore, we should save and restore it. For example `io_binwrite` calls `rb_fiber_scheduler_unblock` and if `errno` is reset to 0 by user code, it will break the error handling in `io_write`. + // If we explicitly preserve `errno` in `io_binwrite` and other similar functions (e.g. by returning it), this code is no longer needed. I hope in the future we will be able to remove it. + int saved_errno = errno; + + VALUE result = rb_funcall(scheduler, id_unblock, 2, blocker, fiber); + + errno = saved_errno; + + return result; } /* |