Shell: Block on the existing event loop instead of pushing a new one

This patch makes `Shell::block_on_job()` pump the event loop while the
job it's waiting for hasn't finished.
As this no longer pushes new event loops, it has the effect of
flattening the stack as well.
Fixes #4976.

1 files changed, 4 insertions, 3 deletions

diff --git a/Userland/Shell/Shell.cpp b/Userland/Shell/Shell.cpp
index ca51af64c8..5d7006a614 100644
--- a/Userland/Shell/Shell.cpp
+++ b/Userland/Shell/Shell.cpp
@@ -1079,17 +1079,18 @@ void Shell::block_on_job(RefPtr<Job> job)
         }
     } };
 
-    Core::EventLoop loop;
+    bool job_exited { false };
     job->on_exit = [&, old_exit = move(job->on_exit)](auto job) {
         if (old_exit)
             old_exit(job);
-        loop.quit(0);
+        job_exited = true;
     };
 
     if (job->exited())
         return;
 
-    loop.exec();
+    while (!job_exited)
+        Core::EventLoop::current().pump();
 
     // If the job is part of a pipeline, wait for the rest of the members too.
     if (auto command = job->command_ptr())