mdw@git.distorted.org.uk Git - xtoys/blob - xwait.c

   1 /* -*-c-*-
   2  *
   3  * $Id: xwait.c,v 1.2 1998/11/18 21:25:06 mdw Exp $
   4  *
   5  * Wait until prodded by another X client
   6  *
   7  * (c) 1998 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the Edgeware X tools collection.
  13  *
  14  * X tools is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * X tools is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with X tools; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: xwait.c,v $
  32  * Revision 1.2  1998/11/18 21:25:06  mdw
  33  * Reap dead children as they arrive.  The previous shell may have
  34  * carelessly left them behind.
  35  *
  36  * Revision 1.1  1998/11/16 23:00:49  mdw
  37  * Initial versions.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include <signal.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47
  48 #include <sys/types.h>
  49 #include <sys/wait.h>
  50 #include <unistd.h>
  51
  52 #include <X11/Xlib.h>
  53 #include <X11/Xutil.h>
  54
  55 #include "xwait.h"
  56
  57 /*----- Main code ---------------------------------------------------------*/
  58
  59 /* --- @sigchld@ --- */
  60
  61 static void sigchld(int sig)
  62 {
  63   while (waitpid(-1, 0, WNOHANG) > 0)
  64     ;
  65 }
  66
  67 /* --- @main@ --- */
  68
  69 int main(int argc, char *argv[])
  70 {
  71   char *display = 0;
  72   Display *dpy;
  73   Atom xwait_die;
  74   XEvent ev;
  75   char *atom = XWAIT_DIE;
  76   char *msg = XWAIT_DIE_MSG;
  77   unsigned f = 0;
  78
  79   enum {
  80     f_force = 1
  81   };
  82
  83   /* --- Parse options --- */
  84
  85   for (;;) {
  86     int i = getopt(argc, argv, "d:a:m:f");
  87     if (i < 0)
  88       break;
  89     switch (i) {
  90       case 'd':
  91         display = optarg;
  92         break;
  93       case 'a':
  94         atom = optarg;
  95         break;
  96       case 'm':
  97         msg = optarg;
  98         break;
  99       case 'f':
 100         f |= f_force;
 101         break;
 102       default:
 103         fprintf(stderr,
 104                 "Usage: xwait [-f] [-d DISPLAY] [-a ATOM] [-m MSG]\n");
 105         exit(EXIT_FAILURE);
 106         break;
 107     }
 108   }
 109
 110   /* --- Connect to the X display --- */
 111
 112   dpy = XOpenDisplay(display);
 113   if (!dpy) {
 114     fprintf(stderr, "xwait: couldn't open display\n");
 115     exit(EXIT_FAILURE);
 116   }
 117
 118   /* --- Fetch the property name atom --- */
 119
 120   xwait_die = XInternAtom(dpy, atom, False);
 121
 122   /* --- Mark ourselves as listening to all the screens --- */
 123
 124   {
 125     int i;
 126     int nsc = ScreenCount(dpy);
 127
 128     /* --- First pass: make sure there's not a process already here --- */
 129
 130     if ((f & f_force) == 0) {
 131       for (i = 0; i < nsc; i++) {
 132         Window win = RootWindow(dpy, i);
 133         XTextProperty prop;
 134
 135         if (XGetTextProperty(dpy, win, &prop, xwait_die)) {
 136           fprintf(stderr, "xwait: already waiting for `%s'\n", atom);
 137           exit(EXIT_FAILURE);
 138         }
 139       }
 140     }
 141
 142     /* --- Second pass: set up listening to the property --- */
 143
 144     for (i = 0; i < nsc; i++) {
 145       Window win = RootWindow(dpy, i);
 146       XTextProperty prop;
 147       char *imsg = "XWAIT_READY";
 148
 149       XStringListToTextProperty(&imsg, 1, &prop);
 150       XSetTextProperty(dpy, win, &prop, xwait_die);
 151       XSelectInput(dpy, win, PropertyChangeMask);
 152     }
 153   }
 154
 155   /* --- Set up a handler when children die --- *
 156    *
 157    * I don't fork any children?  Why is this useful?  Because I've been
 158    * execed from a shell which started lots of background processes, and
 159    * they'll zombie themselves otherwise.
 160    */
 161
 162   {
 163     struct sigaction sa;
 164
 165     sa.sa_handler = sigchld;
 166     sigemptyset(&sa.sa_mask);
 167     sigaddset(&sa.sa_mask, SIGCHLD);
 168     sa.sa_flags = 0;
 169     sigaction(SIGCHLD, &sa, 0);
 170   }
 171
 172   /* --- Now wait for an event --- */
 173
 174   for (;;) {
 175     XNextEvent(dpy, &ev);
 176     switch (ev.type) {
 177       case PropertyNotify:
 178         if (ev.xproperty.atom == xwait_die) {
 179           XTextProperty prop;
 180           char **sl;
 181           int c;
 182
 183           if (XGetTextProperty(dpy, ev.xproperty.window, &prop, xwait_die)) {
 184             XTextPropertyToStringList(&prop, &sl, &c);
 185             if (strcmp(sl[0], msg) == 0)
 186               goto exit;
 187             XFreeStringList(sl);
 188           }
 189         }
 190     }
 191   }
 192
 193   /* --- Finished: remove the property from all the screens --- */
 194
 195 exit:
 196   {
 197     int i;
 198     int nsc = ScreenCount(dpy);
 199
 200     for (i = 0; i < nsc; i++)
 201       XDeleteProperty(dpy, RootWindow(dpy, i), xwait_die);
 202   }
 203
 204   /* --- Go away --- */
 205
 206   XCloseDisplay(dpy);
 207   return (0);
 208 }
 209
 210 /*----- That's all, folks -------------------------------------------------*/