Shell: Keep the TTY on the same pgroup to get tty signals

This allows the shell to be notified about SIGWINCH even when a child
process is running in the foreground.

Shell/AST.cpp

@@ -799,7 +799,7 @@ RefPtr<Value> Execute::run(RefPtr<Shell> shell)
                 } else if (command.should_notify_if_in_background) {
                     if (job)
                         job->set_running_in_background(true);
-                    shell->take_back_stdin();
+                    shell->restore_stdin();
                 }
             }
         }

Shell/Shell.cpp

@@ -435,8 +435,6 @@ RefPtr<Job> Shell::run_command(AST::Command& command)
         return nullptr;
     }
     if (child == 0) {
-        setpgid(0, 0);
-        tcsetpgrp(0, getpid());
         tcsetattr(0, TCSANOW, &default_termios);
         for (auto& rewiring : rewirings) {
 #ifdef SH_DEBUG
@@ -511,14 +509,16 @@ bool Shell::run_file(const String& filename, bool explicitly_invoked)
     run_command(data);
     return true;
 }
-void Shell::take_back_stdin()
+void Shell::restore_stdin()
 {
-    tcsetpgrp(0, m_pid);
     tcsetattr(0, TCSANOW, &termios);
 }
 
 void Shell::block_on_job(RefPtr<Job> job)
 {
+    ScopedValueRollback accepting_signal_rollback(m_is_accepting_signals);
+    m_is_accepting_signals = false;
+
     if (!job)
         return;
 
@@ -529,13 +529,13 @@ void Shell::block_on_job(RefPtr<Job> job)
         loop.quit(0);
     };
     if (job->exited()) {
-        take_back_stdin();
+        restore_stdin();
         return;
     }
 
     loop.exec();
 
-    take_back_stdin();
+    restore_stdin();
 }
 
 String Shell::get_history_path()
@@ -872,7 +872,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_option(const String& program_
 
 bool Shell::read_single_line()
 {
-    take_back_stdin();
+    restore_stdin();
     auto line_result = editor->get_line(prompt());
 
     if (line_result.is_error()) {

Shell/Shell.h

@@ -71,6 +71,8 @@ class Shell : public Core::Object {
 public:
     constexpr static auto init_file_path = "~/shell-init.sh";
 
+    bool is_accepting_signals() const { return m_is_accepting_signals; }
+
     int run_command(const StringView&);
     RefPtr<Job> run_command(AST::Command&);
     bool run_file(const String&, bool explicitly_invoked = true);
@@ -104,7 +106,7 @@ public:
     Vector<Line::CompletionSuggestion> complete_user(const String&, size_t offset);
     Vector<Line::CompletionSuggestion> complete_option(const String&, const String&, size_t offset);
 
-    void take_back_stdin();
+    void restore_stdin();
 
     u64 find_last_job_id() const;
     const Job* find_job(u64 id);
@@ -180,6 +182,7 @@ private:
 
     StringBuilder m_complete_line_builder;
     bool m_should_ignore_jobs_on_next_exit { false };
+    bool m_is_accepting_signals { true };
     pid_t m_pid { 0 };
 
     HashMap<String, RefPtr<AST::Value>> m_local_variables;

Shell/main.cpp

@@ -61,6 +61,8 @@ int main(int argc, char** argv)
     Core::EventLoop loop;
 
     signal(SIGINT, [](int) {
+        if (!s_shell->is_accepting_signals())
+            return;
         editor->interrupted();
     });
 
@@ -68,7 +70,12 @@ int main(int argc, char** argv)
         editor->resized();
     });
 
+    signal(SIGTTIN, [](int) {});
+    signal(SIGTTOU, [](int) {});
+
     signal(SIGHUP, [](int) {
+        if (!s_shell->is_accepting_signals())
+            return;
         s_shell->save_history();
     });