Rework the way UI can trigger a client quitting

Add a UserInterface::is_ok method and return false on
SIGHUP/stdin closing/socket dropping

This should be cleaner and more robust than the previous SIGHUP
handling code.

Fixes #1594

1 files changed, 2 insertions, 0 deletions

diff --git a/src/user_interface.hh b/src/user_interface.hh
index d8139336..c3313890 100644
--- a/src/user_interface.hh
+++ b/src/user_interface.hh
@@ -47,6 +47,8 @@ class UserInterface
 public:
     virtual ~UserInterface() = default;
 
+    virtual bool is_ok() const = 0;
+
     virtual void menu_show(ConstArrayView<DisplayLine> choices,
                            DisplayCoord anchor, Face fg, Face bg,
                            MenuStyle style) = 0;