x11conn.c 7.8 KB

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  1. /*
  2. X11 support for the Midnight Commander.
  3. Copyright (C) 2005-2024
  4. Free Software Foundation, Inc.
  5. Written by:
  6. Roland Illig <roland.illig@gmx.de>, 2005.
  7. This file is part of the Midnight Commander.
  8. The Midnight Commander is free software: you can redistribute it
  9. and/or modify it under the terms of the GNU General Public License as
  10. published by the Free Software Foundation, either version 3 of the License,
  11. or (at your option) any later version.
  12. The Midnight Commander is distributed in the hope that it will be useful,
  13. but WITHOUT ANY WARRANTY; without even the implied warranty of
  14. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15. GNU General Public License for more details.
  16. You should have received a copy of the GNU General Public License
  17. along with this program. If not, see <http://www.gnu.org/licenses/>.
  18. */
  19. /** \file x11conn.c
  20. * \brief Source: X11 support
  21. * \warning This code uses setjmp() and longjmp(). Before you modify _anything_ here,
  22. * please read the relevant sections of the C standard.
  23. */
  24. #include <config.h>
  25. #include <setjmp.h>
  26. #include <X11/Xlib.h>
  27. #ifdef HAVE_GMODULE
  28. #include <gmodule.h>
  29. #endif
  30. #include "lib/global.h"
  31. #include "x11conn.h"
  32. /*** global variables ****************************************************************************/
  33. /*** file scope macro definitions ****************************************************************/
  34. #ifndef HAVE_GMODULE
  35. #define func_XOpenDisplay XOpenDisplay
  36. #define func_XCloseDisplay XCloseDisplay
  37. #define func_XSetErrorHandler XSetErrorHandler
  38. #define func_XSetIOErrorHandler XSetIOErrorHandler
  39. #define func_XQueryPointer XQueryPointer
  40. #endif
  41. /*** file scope type declarations ****************************************************************/
  42. typedef int (*mc_XErrorHandler_callback) (Display *, XErrorEvent *);
  43. typedef int (*mc_XIOErrorHandler_callback) (Display *);
  44. /*** forward declarations (file scope functions) *************************************************/
  45. /*** file scope variables ************************************************************************/
  46. #ifdef HAVE_GMODULE
  47. static Display *(*func_XOpenDisplay) (_Xconst char *);
  48. static int (*func_XCloseDisplay) (Display *);
  49. static mc_XErrorHandler_callback (*func_XSetErrorHandler) (mc_XErrorHandler_callback);
  50. static mc_XIOErrorHandler_callback (*func_XSetIOErrorHandler) (mc_XIOErrorHandler_callback);
  51. static Bool (*func_XQueryPointer) (Display *, Window, Window *, Window *,
  52. int *, int *, int *, int *, unsigned int *);
  53. static GModule *x11_module;
  54. #endif
  55. static gboolean handlers_installed = FALSE;
  56. /* This flag is set as soon as an X11 error is reported. Usually that
  57. * means that the DISPLAY is not available anymore. We do not try to
  58. * reconnect, as that would violate the X11 protocol. */
  59. static gboolean lost_connection = FALSE;
  60. static jmp_buf x11_exception; /* FIXME: get a better name */
  61. static gboolean longjmp_allowed = FALSE;
  62. /* --------------------------------------------------------------------------------------------- */
  63. /*** file scope functions ************************************************************************/
  64. /* --------------------------------------------------------------------------------------------- */
  65. static int
  66. x_io_error_handler (Display *dpy)
  67. {
  68. (void) dpy;
  69. lost_connection = TRUE;
  70. if (longjmp_allowed)
  71. {
  72. longjmp_allowed = FALSE;
  73. longjmp (x11_exception, 1);
  74. }
  75. return 0;
  76. }
  77. /* --------------------------------------------------------------------------------------------- */
  78. static int
  79. x_error_handler (Display *dpy, XErrorEvent *ee)
  80. {
  81. (void) ee;
  82. (void) func_XCloseDisplay (dpy);
  83. return x_io_error_handler (dpy);
  84. }
  85. /* --------------------------------------------------------------------------------------------- */
  86. static void
  87. install_error_handlers (void)
  88. {
  89. if (handlers_installed)
  90. return;
  91. (void) func_XSetErrorHandler (x_error_handler);
  92. (void) func_XSetIOErrorHandler (x_io_error_handler);
  93. handlers_installed = TRUE;
  94. }
  95. /* --------------------------------------------------------------------------------------------- */
  96. static gboolean
  97. x11_available (void)
  98. {
  99. #ifdef HAVE_GMODULE
  100. if (lost_connection)
  101. return FALSE;
  102. if (x11_module != NULL)
  103. return TRUE;
  104. x11_module = g_module_open ("X11", G_MODULE_BIND_LAZY);
  105. if (x11_module == NULL)
  106. x11_module = g_module_open ("libX11.so.6", G_MODULE_BIND_LAZY);
  107. if (x11_module == NULL)
  108. return FALSE;
  109. if (!g_module_symbol (x11_module, "XOpenDisplay", (void *) &func_XOpenDisplay))
  110. goto cleanup;
  111. if (!g_module_symbol (x11_module, "XCloseDisplay", (void *) &func_XCloseDisplay))
  112. goto cleanup;
  113. if (!g_module_symbol (x11_module, "XQueryPointer", (void *) &func_XQueryPointer))
  114. goto cleanup;
  115. if (!g_module_symbol (x11_module, "XSetErrorHandler", (void *) &func_XSetErrorHandler))
  116. goto cleanup;
  117. if (!g_module_symbol (x11_module, "XSetIOErrorHandler", (void *) &func_XSetIOErrorHandler))
  118. goto cleanup;
  119. install_error_handlers ();
  120. return TRUE;
  121. cleanup:
  122. func_XOpenDisplay = 0;
  123. func_XCloseDisplay = 0;
  124. func_XQueryPointer = 0;
  125. func_XSetErrorHandler = 0;
  126. func_XSetIOErrorHandler = 0;
  127. g_module_close (x11_module);
  128. x11_module = NULL;
  129. return FALSE;
  130. #else
  131. install_error_handlers ();
  132. return !(lost_connection);
  133. #endif
  134. }
  135. /* --------------------------------------------------------------------------------------------- */
  136. /*** public functions ****************************************************************************/
  137. /* --------------------------------------------------------------------------------------------- */
  138. Display *
  139. mc_XOpenDisplay (const char *displayname)
  140. {
  141. if (x11_available ())
  142. {
  143. if (setjmp (x11_exception) == 0)
  144. {
  145. Display *retval;
  146. /* cppcheck-suppress redundantAssignment */
  147. longjmp_allowed = TRUE;
  148. retval = func_XOpenDisplay (displayname);
  149. /* cppcheck-suppress redundantAssignment */
  150. longjmp_allowed = FALSE;
  151. return retval;
  152. }
  153. }
  154. return NULL;
  155. }
  156. /* --------------------------------------------------------------------------------------------- */
  157. int
  158. mc_XCloseDisplay (Display *display)
  159. {
  160. if (x11_available ())
  161. {
  162. if (setjmp (x11_exception) == 0)
  163. {
  164. int retval;
  165. /* cppcheck-suppress redundantAssignment */
  166. longjmp_allowed = TRUE;
  167. retval = func_XCloseDisplay (display);
  168. /* cppcheck-suppress redundantAssignment */
  169. longjmp_allowed = FALSE;
  170. return retval;
  171. }
  172. }
  173. return 0;
  174. }
  175. /* --------------------------------------------------------------------------------------------- */
  176. Bool
  177. mc_XQueryPointer (Display *display, Window win, Window *root_return,
  178. Window *child_return, int *root_x_return, int *root_y_return,
  179. int *win_x_return, int *win_y_return, unsigned int *mask_return)
  180. {
  181. Bool retval;
  182. if (x11_available ())
  183. {
  184. if (setjmp (x11_exception) == 0)
  185. {
  186. /* cppcheck-suppress redundantAssignment */
  187. longjmp_allowed = TRUE;
  188. retval = func_XQueryPointer (display, win, root_return,
  189. child_return, root_x_return, root_y_return,
  190. win_x_return, win_y_return, mask_return);
  191. /* cppcheck-suppress redundantAssignment */
  192. longjmp_allowed = FALSE;
  193. return retval;
  194. }
  195. }
  196. *root_return = None;
  197. *child_return = None;
  198. *root_x_return = 0;
  199. *root_y_return = 0;
  200. *win_x_return = 0;
  201. *win_y_return = 0;
  202. *mask_return = 0;
  203. return False;
  204. }
  205. /* --------------------------------------------------------------------------------------------- */