src/login/multi-seat-x.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25 #include <libudev.h>
  26
  27 #include "util.h"
  28
  29 int main(int argc, char *argv[]) {
  30
  31         struct udev *udev = NULL;
  32         struct udev_enumerate *enumerator = NULL;
  33         struct udev_list_entry *first, *item;
  34         int i;
  35         const char *seat = NULL;
  36         char **new_argv;
  37         char *path = NULL, *device_node = NULL;
  38         int r;
  39         FILE *f = NULL;
  40
  41         /* This binary will go away as soon as X natively supports
  42          * display enumeration with udev in a way that covers both PCI
  43          * and USB. */
  44
  45         /* This will simply determine the fb device id of the graphics
  46          * device assigned to a seat and write a configuration file
  47          * from it and then spawn the real X server. */
  48
  49         /* If this file is removed, don't forget to remove the code
  50          * that invokes this in gdm and other display managers. */
  51
  52         for (i = 1; i < argc; i++)
  53                 if (streq(argv[i], "-seat"))
  54                         seat = argv[i+1];
  55
  56         if (isempty(seat) || streq(seat, "seat0")) {
  57                 argv[0] = (char*) X_SERVER;
  58                 execv(X_SERVER, argv);
  59                 log_error("Failed to execute real X server: %m");
  60                 goto fail;
  61         }
  62
  63         udev = udev_new();
  64         if (!udev) {
  65                 log_error("Failed to allocate udev environment.");
  66                 goto fail;
  67         }
  68
  69         enumerator = udev_enumerate_new(udev);
  70         if (!enumerator) {
  71                 log_error("Failed to allocate udev enumerator.");
  72                 goto fail;
  73         }
  74
  75         udev_enumerate_add_match_subsystem(enumerator, "graphics");
  76         udev_enumerate_add_match_tag(enumerator, seat);
  77
  78         r = udev_enumerate_scan_devices(enumerator);
  79         if (r < 0) {
  80                 log_error("Failed to enumerate devices.");
  81                 goto fail;
  82         }
  83
  84         first = udev_enumerate_get_list_entry(enumerator);
  85         udev_list_entry_foreach(item, first) {
  86                 struct udev_device *d;
  87                 const char *dn;
  88
  89                 d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
  90                 if (!d)
  91                         continue;
  92
  93                 dn = udev_device_get_devnode(d);
  94
  95                 if (dn) {
  96                         device_node = strdup(dn);
  97                         if (!device_node) {
  98                                 udev_device_unref(d);
  99                                 log_error("Out of memory.");
 100                                 goto fail;
 101                         }
 102                 }
 103
 104                 udev_device_unref(d);
 105
 106                 if (device_node)
 107                         break;
 108         }
 109
 110         if (!device_node) {
 111                 log_error("Failed to find device node for seat %s.", seat);
 112                 goto fail;
 113         }
 114
 115         r = safe_mkdir("/run/systemd/multi-session-x", 0755, 0, 0);
 116         if (r < 0) {
 117                 log_error("Failed to create directory: %s", strerror(-r));
 118                 goto fail;
 119         }
 120
 121         path = strappend("/run/systemd/multi-session-x/", seat);
 122         if (!path) {
 123                 log_error("Out of memory");
 124                 goto fail;
 125         }
 126
 127         f = fopen(path, "we");
 128         if (!f) {
 129                 log_error("Failed to write configuration file: %m");
 130                 goto fail;
 131         }
 132
 133         fprintf(f,
 134                 "Section \"Device\"\n"
 135                 "        Identifier \"udev\"\n"
 136                 "        Driver \"fbdev\"\n"
 137                 "        Option \"fbdev\" \"%s\"\n"
 138                 "EndSection\n"
 139                 "Section \"ServerFlags\"\n"
 140                 "        Option \"AutoAddDevices\" \"True\"\n"
 141                 "        Option \"AllowEmptyInput\" \"True\"\n"
 142                 "        Option \"DontVTSwitch\" \"True\"\n"
 143                 "EndSection\n"
 144                 "Section \"InputClass\"\n"
 145                 "        Identifier \"Force Input Devices to Seat\"\n"
 146                 "        Option \"GrabDevice\" \"True\"\n"
 147                 "EndSection\n",
 148                 device_node);
 149
 150         fflush(f);
 151
 152         if (ferror(f)) {
 153                 log_error("Failed to write configuration file: %m");
 154                 goto fail;
 155         }
 156
 157         fclose(f);
 158         f = NULL;
 159
 160         new_argv = alloca(sizeof(char*) * (argc + 3 + 1));
 161         memcpy(new_argv, argv, sizeof(char*) * (argc + 2 + 1));
 162
 163         new_argv[0] = (char*) X_SERVER;
 164         new_argv[argc+0] = (char*) "-config";
 165         new_argv[argc+1] = path;
 166         new_argv[argc+2] = (char*) "-sharevts";
 167         new_argv[argc+3] = NULL;
 168
 169         udev_enumerate_unref(enumerator);
 170         enumerator = NULL;
 171
 172         udev_unref(udev);
 173         udev = NULL;
 174
 175         free(device_node);
 176         device_node = NULL;
 177
 178         execv(X_SERVER, new_argv);
 179         log_error("Failed to execute real X server: %m");
 180
 181 fail:
 182         if (enumerator)
 183                 udev_enumerate_unref(enumerator);
 184
 185         if (udev)
 186                 udev_unref(udev);
 187
 188         free(path);
 189         free(device_node);
 190
 191         if (f)
 192                 fclose(f);
 193
 194         return EXIT_FAILURE;
 195 }