Fix ctrl-h on terminals where that is the same as backspace (hhkb)

If the terminfo "kbs" (key_backspace) attribute is ctrl-h, curses will
treat any occurence of ctrl-h as KEY_BACKSPACE.  Work around that by
converting back to CK_BKSP == 0x8 (ctrl-h) if kbs is set ctrl-h.
However, on sane terminals where backspace generates ctrl-?, don't smash
the two.

Fixes #7013.

1 files changed, 9 insertions, 0 deletions

diff --git a/crawl-ref/source/libunix.cc b/crawl-ref/source/libunix.cc
index 3060c48039..eeb8419d55 100644
--- a/crawl-ref/source/libunix.cc
+++ b/crawl-ref/source/libunix.cc
@@ -21,6 +21,7 @@
 #include <unistd.h>
 #include <stdarg.h>
 #include <ctype.h>
+#include <term.h>
 #define _LIBUNIX_IMPLEMENTATION
 #include "libunix.h"
 #include "defines.h"
@@ -384,6 +385,14 @@ int unixcurses_get_vi_key(int keyin)
     case KEY_SLEFT:  return 'H';
     case KEY_SRIGHT: return 'L';
     case KEY_BTAB:   return CK_SHIFT_TAB;
+    case KEY_BACKSPACE:
+        // If key_backspace (kbs) is ctrl-h, curses generates KEY_BACKSPACE
+        // for the ctrl-h key.  Work around that by converting back to CK_BKSP.
+        static const char * const kbs = tigetstr("kbs");
+        static const int bskey = (kbs && kbs != (const char *) -1
+                                      && kbs == string("\010")) ? CK_BKSP
+                                                                : KEY_BACKSPACE;
+        return bskey;
     }
     return keyin;
 }