Ignore signals during command execution

Disable signal handlers in wins_prepare_external() and reactivate them
in wins_unprepare_external().

Before, it was possible that resizing the window during editor/pager
mode resulted in the calcurse main screen appearing on top.

Addresses BUG#9.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/calcurse.h

@@ -883,6 +883,8 @@ void recur_apoint_paste_item(void);
 /* sigs.c */
 void sigs_init(void);
 unsigned sigs_set_hdlr(int, void (*)(int));
+void sigs_ignore(void);
+void sigs_unignore(void);
 
 /* todo.c */
 extern llist_t todolist;

src/sigs.c

@@ -108,3 +108,17 @@ void sigs_init()
       || !sigs_set_hdlr(SIGINT, SIG_IGN))
     exit_calcurse(1);
 }
+
+/* Ignore SIGWINCH and SIGTERM signals. */
+void sigs_ignore(void)
+{
+  sigs_set_hdlr(SIGWINCH, SIG_IGN);
+  sigs_set_hdlr(SIGTERM, SIG_IGN);
+}
+
+/* No longer ignore SIGWINCH and SIGTERM signals. */
+void sigs_unignore(void)
+{
+  sigs_set_hdlr(SIGWINCH, generic_hdlr);
+  sigs_set_hdlr(SIGTERM, generic_hdlr);
+}

src/wins.c

@@ -591,16 +591,20 @@ void wins_prepare_external(void)
   clear();
   wins_refresh();
   endwin();
+  sigs_ignore();
 }
 
 /* Restore windows when returning from an external command. */
 void wins_unprepare_external(void)
 {
+  sigs_unignore();
   reset_prog_mode();
   clearok(curscr, TRUE);
   curs_set(0);
   ui_mode = UI_CURSES;
   wins_refresh();
+  wins_reinit();
+  wins_update(FLAG_ALL);
   if (notify_bar())
     notify_start_main_thread();
 }