lib/tty/x11conn.c

   1 /*
   2    X11 support for the Midnight Commander.
   3
   4    Copyright (C) 2005, 2007 Free Software Foundation, Inc.
   5
   6    Written by:
   7    Roland Illig <roland.illig@gmx.de>, 2005.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  */
  23
  24 /** \file x11conn.c
  25  *  \brief Source: X11 support
  26  *  \warning This code uses setjmp() and longjmp(). Before you modify _anything_ here,
  27  *  please read the relevant sections of the C standard.
  28  */
  29
  30 #include <config.h>
  31
  32 #ifndef HAVE_TEXTMODE_X11_SUPPORT
  33 typedef int dummy;              /* C99 forbids empty compilation unit */
  34 #else
  35
  36 #include <setjmp.h>
  37 #include <X11/Xlib.h>
  38 #ifdef HAVE_GMODULE
  39 #include <gmodule.h>
  40 #endif
  41
  42 #include "lib/global.h"
  43 #include "x11conn.h"
  44
  45 /*** global variables ****************************************************************************/
  46
  47 /*** file scope macro definitions ****************************************************************/
  48
  49 #ifndef HAVE_GMODULE
  50 #define func_XOpenDisplay       XOpenDisplay
  51 #define func_XCloseDisplay      XCloseDisplay
  52 #define func_XSetErrorHandler   XSetErrorHandler
  53 #define func_XSetIOErrorHandler XSetIOErrorHandler
  54 #define func_XQueryPointer      XQueryPointer
  55 #endif
  56
  57 /*** file scope type declarations ****************************************************************/
  58
  59 typedef int (*mc_XErrorHandler_callback) (Display *, XErrorEvent *);
  60 typedef int (*mc_XIOErrorHandler_callback) (Display *);
  61
  62 /*** file scope variables ************************************************************************/
  63
  64 #ifdef HAVE_GMODULE
  65 static Display *(*func_XOpenDisplay) (_Xconst char *);
  66 static int (*func_XCloseDisplay) (Display *);
  67 static mc_XErrorHandler_callback (*func_XSetErrorHandler) (mc_XErrorHandler_callback);
  68 static mc_XIOErrorHandler_callback (*func_XSetIOErrorHandler) (mc_XIOErrorHandler_callback);
  69 static Bool (*func_XQueryPointer) (Display *, Window, Window *, Window *,
  70                                    int *, int *, int *, int *, unsigned int *);
  71 static GModule *x11_module;
  72 #endif
  73
  74 static gboolean handlers_installed = FALSE;
  75
  76 /* This flag is set as soon as an X11 error is reported. Usually that
  77  * means that the DISPLAY is not available anymore. We do not try to
  78  * reconnect, as that would violate the X11 protocol. */
  79 static gboolean lost_connection = FALSE;
  80
  81 static jmp_buf x11_exception;   /* FIXME: get a better name */
  82 static gboolean longjmp_allowed = FALSE;
  83
  84 /*** file scope functions ************************************************************************/
  85 /* --------------------------------------------------------------------------------------------- */
  86
  87 static int
  88 x_io_error_handler (Display * dpy)
  89 {
  90     (void) dpy;
  91
  92     lost_connection = TRUE;
  93     if (longjmp_allowed)
  94     {
  95         longjmp_allowed = FALSE;
  96         longjmp (x11_exception, 1);
  97     }
  98     return 0;
  99 }
 100
 101 /* --------------------------------------------------------------------------------------------- */
 102
 103 static int
 104 x_error_handler (Display * dpy, XErrorEvent * ee)
 105 {
 106     (void) ee;
 107     (void) func_XCloseDisplay (dpy);
 108     return x_io_error_handler (dpy);
 109 }
 110
 111 /* --------------------------------------------------------------------------------------------- */
 112
 113 static void
 114 install_error_handlers (void)
 115 {
 116     if (handlers_installed)
 117         return;
 118
 119     (void) func_XSetErrorHandler (x_error_handler);
 120     (void) func_XSetIOErrorHandler (x_io_error_handler);
 121     handlers_installed = TRUE;
 122 }
 123
 124 /* --------------------------------------------------------------------------------------------- */
 125
 126 static gboolean
 127 x11_available (void)
 128 {
 129 #ifdef HAVE_GMODULE
 130     gchar *x11_module_fname;
 131
 132     if (lost_connection)
 133         return FALSE;
 134
 135     if (x11_module != NULL)
 136         return TRUE;
 137
 138     x11_module_fname = g_module_build_path (NULL, "X11");
 139     x11_module = g_module_open (x11_module_fname, G_MODULE_BIND_LAZY);
 140     if (x11_module == NULL)
 141         x11_module = g_module_open ("libX11.so.6", G_MODULE_BIND_LAZY);
 142
 143     g_free (x11_module_fname);
 144
 145     if (x11_module == NULL)
 146         return FALSE;
 147
 148     if (!g_module_symbol (x11_module, "XOpenDisplay", (void *) &func_XOpenDisplay))
 149         goto cleanup;
 150     if (!g_module_symbol (x11_module, "XCloseDisplay", (void *) &func_XCloseDisplay))
 151         goto cleanup;
 152     if (!g_module_symbol (x11_module, "XQueryPointer", (void *) &func_XQueryPointer))
 153         goto cleanup;
 154     if (!g_module_symbol (x11_module, "XSetErrorHandler", (void *) &func_XSetErrorHandler))
 155         goto cleanup;
 156     if (!g_module_symbol (x11_module, "XSetIOErrorHandler", (void *) &func_XSetIOErrorHandler))
 157         goto cleanup;
 158
 159     install_error_handlers ();
 160     return TRUE;
 161
 162   cleanup:
 163     func_XOpenDisplay = 0;
 164     func_XCloseDisplay = 0;
 165     func_XQueryPointer = 0;
 166     func_XSetErrorHandler = 0;
 167     func_XSetIOErrorHandler = 0;
 168     g_module_close (x11_module);
 169     x11_module = NULL;
 170     return FALSE;
 171 #else
 172     install_error_handlers ();
 173     return !(lost_connection);
 174 #endif
 175 }
 176
 177 /* --------------------------------------------------------------------------------------------- */
 178 /*** public functions ****************************************************************************/
 179 /* --------------------------------------------------------------------------------------------- */
 180
 181 Display *
 182 mc_XOpenDisplay (const char *displayname)
 183 {
 184     Display *retval;
 185
 186     if (x11_available ())
 187     {
 188         if (setjmp (x11_exception) == 0)
 189         {
 190             longjmp_allowed = TRUE;
 191             retval = func_XOpenDisplay (displayname);
 192             longjmp_allowed = FALSE;
 193             return retval;
 194         }
 195     }
 196     return NULL;
 197 }
 198
 199 /* --------------------------------------------------------------------------------------------- */
 200
 201 int
 202 mc_XCloseDisplay (Display * display)
 203 {
 204     int retval;
 205
 206     if (x11_available ())
 207     {
 208         if (setjmp (x11_exception) == 0)
 209         {
 210             longjmp_allowed = TRUE;
 211             retval = func_XCloseDisplay (display);
 212             longjmp_allowed = FALSE;
 213             return retval;
 214         }
 215     }
 216     return 0;
 217 }
 218
 219 /* --------------------------------------------------------------------------------------------- */
 220
 221 Bool
 222 mc_XQueryPointer (Display * display, Window win, Window * root_return,
 223                   Window * child_return, int *root_x_return, int *root_y_return,
 224                   int *win_x_return, int *win_y_return, unsigned int *mask_return)
 225 {
 226     Bool retval;
 227
 228     if (x11_available ())
 229     {
 230         if (setjmp (x11_exception) == 0)
 231         {
 232             longjmp_allowed = TRUE;
 233             retval = func_XQueryPointer (display, win, root_return,
 234                                          child_return, root_x_return, root_y_return,
 235                                          win_x_return, win_y_return, mask_return);
 236             longjmp_allowed = FALSE;
 237             return retval;
 238         }
 239     }
 240     *root_return = None;
 241     *child_return = None;
 242     *root_x_return = 0;
 243     *root_y_return = 0;
 244     *win_x_return = 0;
 245     *win_y_return = 0;
 246     *mask_return = 0;
 247     return False;
 248 }
 249
 250 /* --------------------------------------------------------------------------------------------- */
 251
 252 #endif /* HAVE_TEXTMODE_X11_SUPPORT */