Update vt ioctl usage

[sojka/lightdm.git] / src / vt.c

diff --git a/src/vt.c b/src/vt.c
index fb570d10bc2d89985374c0cea48b64121ca06446..d784a8c83174d4bd894e378f94f4fc279a45dc26 100644 (file)
--- a/src/vt.c
+++ b/src/vt.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2010-2011 Robert Ancell.
  * Author: Robert Ancell <robert.ancell@canonical.com>
- * 
+ *
  * This program is free software: you can redistribute it and/or modify it under
  * the terms of the GNU General Public License as published by the Free Software
  * Foundation, either version 3 of the License, or (at your option) any later
@@ -21,58 +21,146 @@
 #endif
 
 #include "vt.h"
+#include "configuration.h"
+
+static GList *used_vts = NULL;
+
+static gint
+open_tty (void)
+{
+    int fd;
+
+    fd = g_open ("/dev/tty0", O_RDONLY | O_NOCTTY, 0);
+    if (fd < 0)
+        g_warning ("Error opening /dev/tty0: %s", strerror (errno));
+    return fd;
+}
+
+gboolean
+vt_can_multi_seat (void)
+{
+    /* Quick check to see if we can multi seat.  This is intentionally the
+       same check logind does, just without actually reading from the files.
+       Existence will prove whether we have CONFIG_VT built into the kernel. */
+    return access ("/dev/tty0", F_OK) == 0 &&
+           access ("/sys/class/tty/tty0/active", F_OK) == 0;
+}
 
 gint
 vt_get_active (void)
 {
 #ifdef __linux__
-    gint console_fd;
-    struct vt_stat console_state = { 0 };    
+    gint tty_fd;
+    gint active = -1;
+
+    /* Pretend always active */
+    if (getuid () != 0)
+        return 1;
 
-    console_fd = g_open ("/dev/console", O_RDONLY | O_NOCTTY);
-    if (console_fd < 0)
+    tty_fd = open_tty ();
+    if (tty_fd >= 0)
     {
-        g_warning ("Error opening /dev/console: %s", strerror (errno));
-        return -1;
+        struct vt_stat vt_state = { 0 };
+        if (ioctl (tty_fd, VT_GETSTATE, &vt_state) < 0)
+            g_warning ("Error using VT_GETSTATE on /dev/tty0: %s", strerror (errno));
+        else
+            active = vt_state.v_active;
+        close (tty_fd);
     }
 
-    if (ioctl (console_fd, VT_GETSTATE, &console_state) < 0)
-        g_warning ("Error using VT_GETSTATE on /dev/console: %s", strerror (errno));
-
-    close (console_fd);
-
-    return console_state.v_active;
+    return active;
 #else
     return -1;
-#endif    
+#endif
 }
 
-gint
-vt_get_unused (void)
+void
+vt_set_active (gint number)
 {
 #ifdef __linux__
-    gint console_fd;
-    int number;
+    gint tty_fd;
 
-    console_fd = g_open ("/dev/console", O_RDONLY | O_NOCTTY);
-    if (console_fd < 0)
+    g_debug ("Activating VT %d", number);
+
+    /* Pretend always active */
+    if (getuid () != 0)
+        return;
+
+    tty_fd = open_tty ();
+    if (tty_fd >= 0)
     {
-        g_warning ("Error opening /dev/console: %s", strerror (errno));
-        return -1;
+        int n = number;
+
+        if (ioctl (tty_fd, VT_ACTIVATE, n) < 0)
+        {
+            g_warning ("Error using VT_ACTIVATE %d on /dev/tty0: %s", n, strerror (errno));
+            close (tty_fd);
+            return;
+        }
+
+        /* Wait for the VT to become active to avoid a suspected
+         * race condition somewhere between LightDM, X, ConsoleKit and the kernel.
+         * See https://bugs.launchpad.net/bugs/851612 */
+        if (ioctl (tty_fd, VT_WAITACTIVE, n) < 0)
+            g_warning ("Error using VT_WAITACTIVE %d on /dev/tty0: %s", n, strerror (errno));
+
+        close (tty_fd);
+    }
+#endif
+}
+
+static gboolean
+vt_is_used (gint number)
+{
+    GList *link;
+
+    for (link = used_vts; link; link = link->next)
+    {
+        int n = GPOINTER_TO_INT (link->data);
+        if (n == number)
+            return TRUE;
     }
 
-    if (ioctl (console_fd, VT_OPENQRY, &number) < 0)
-        g_warning ("Error using VT_OPENQRY on /dev/console: %s", strerror (errno));
+    return FALSE;
+}
+
+gint
+vt_get_min (void)
+{
+    gint number;
+
+    number = config_get_integer (config_get_instance (), "LightDM", "minimum-vt");
+    if (number < 1)
+        number = 1;
 
-    close (console_fd);
-  
     return number;
-#else
-    return -1;
-#endif    
+}
+
+gint
+vt_get_unused (void)
+{
+    gint number;
+
+    if (getuid () != 0)
+        return -1;
+
+    number = vt_get_min ();
+    while (vt_is_used (number))
+        number++;
+
+    return number;
+}
+
+void
+vt_ref (gint number)
+{
+    g_debug ("Using VT %d", number);
+    used_vts = g_list_append (used_vts, GINT_TO_POINTER (number));
 }
 
 void
-vt_release (gint number)
+vt_unref (gint number)
 {
+    g_debug ("Releasing VT %d", number);
+    used_vts = g_list_remove (used_vts, GINT_TO_POINTER (number));
 }