Ladybird: Ignore SIGINT when we're being debugged

Let's ignore SIGINT if we're being debugged because GDB incorrectly
forwards the signal to us even when it's set to "nopass". See
https://sourceware.org/bugzilla/show_bug.cgi?id=9425 for details.

Ladybird/main.cpp

@@ -10,18 +10,48 @@
 #include <LibCore/ArgsParser.h>
 #include <LibCore/EventLoop.h>
 #include <LibCore/File.h>
+#include <LibCore/Stream.h>
+#include <LibCore/System.h>
 #include <LibGfx/Font/FontDatabase.h>
 #include <LibMain/Main.h>
 #include <QApplication>
 
 Browser::Settings* s_settings;
 
+static ErrorOr<void> handle_attached_debugger()
+{
+#ifdef AK_OS_LINUX
+ // Let's ignore SIGINT if we're being debugged because GDB
+ // incorrectly forwards the signal to us even when it's set to
+ // "nopass". See https://sourceware.org/bugzilla/show_bug.cgi?id=9425
+ // for details.
+ auto unbuffered_status_file = TRY(Core::Stream::File::open("/proc/self/status"sv, Core::Stream::OpenMode::Read));
+ auto status_file = TRY(Core::Stream::BufferedFile::create(move(unbuffered_status_file)));
+ auto buffer = TRY(ByteBuffer::create_uninitialized(4096));
+ while (TRY(status_file->can_read_line())) {
+ auto line = TRY(status_file->read_line(buffer));
+ auto const parts = line.split_view(':');
+ if (parts.size() < 2 || parts[0] != "TracerPid"sv)
+ continue;
+ auto tracer_pid = parts[1].to_uint<u32>();
+ if (tracer_pid != 0UL) {
+ dbgln("Debugger is attached, ignoring SIGINT");
+ TRY(Core::System::signal(SIGINT, SIG_IGN));
+ }
+ break;
+ }
+#endif
+ return {};
+}
+
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
  // NOTE: This is only used for the Core::Socket inside the IPC connections.
  // FIXME: Refactor things so we can get rid of this somehow.
  Core::EventLoop event_loop;
 
+ TRY(handle_attached_debugger());
+
  QApplication app(arguments.argc, arguments.argv);
 
  platform_init();