Make requested console reports work

cf https://cygwin.com/ml/cygwin-patches/2012-q3/msg00019.html

This enables the following ESC sequences:
ESC[c sends primary device attributes
ESC[>c sends secondary device attributes
ESC[6n sends cursor position report

    * fhandler.h (class dev_console): Add console read-ahead buffer.
    (class fhandler_console): Add peek function for it (for select).
    * fhandler_console.cc (fhandler_console::setup): Init buffer.
    (fhandler_console::read): Check console read-aheader buffer.
    (fhandler_console::char_command): Put responses to terminal
    requests (device status and cursor position reports) into
    common console buffer (shared between CONOUT/CONIN)
    instead of fhandler buffer (separated).
    * select.cc (peek_console): Check console read-ahead buffer.

1 files changed, 6 insertions, 0 deletions

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 134fd716b..1c1862b59 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1352,6 +1352,8 @@ class dev_console
   bool ext_mouse_mode15;
   bool use_focus;
   bool raw_win32_keyboard_mode;
+  char cons_rabuf[40];  // cannot get longer than char buf[40] in char_command
+  char *cons_rapoi;
 
   inline UINT get_console_cp ();
   DWORD con_to_str (char *d, int dlen, WCHAR w);
@@ -1449,6 +1451,10 @@ private:
   int init (HANDLE, DWORD, mode_t);
   bool mouse_aware (MOUSE_EVENT_RECORD& mouse_event);
   bool focus_aware () {return shared_console_info->con.use_focus;}
+  bool get_cons_readahead_valid ()
+  {
+    return shared_console_info->con.cons_rapoi != NULL;
+  }
 
   select_record *select_read (select_stuff *);
   select_record *select_write (select_stuff *);