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- Committer: robert.ancell at gmail
- Date: 2010-04-29 11:08:26 UTC
- Revision ID: robert.ancell@gmail.com-20100429110826-eef3w3c9hl80pxxy
Compiles and does something
added
removed
src/display.c
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/*
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* Copyright (C) 2010 Canonical Ltd.
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* Author: Robert Ancell <robert.ancell@canonical.com>
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version. See http://www.gnu.org/copyleft/gpl.html the full text of the
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* license.
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/wait.h>
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#include <pwd.h>
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#include <unistd.h>
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#include <security/pam_appl.h>
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#include "display.h"
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enum {
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EXITED,
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LAST_SIGNAL
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};
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static guint signals[LAST_SIGNAL] = { 0 };
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struct DisplayPrivate
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{
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/* X process */
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GPid xserver_pid;
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/* Session process (either greeter or user session) */
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GPid session_pid;
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/* Authentication thread */
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GThread *authentication_thread;
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/* Queue to feed responses to the authentication thread */
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GAsyncQueue *authentication_response_queue;
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/* Current D-Bus call context */
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DBusGMethodInvocation *dbus_context;
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/* Authentication handle */
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pam_handle_t *pam_handle;
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/* User logged in as */
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char *username;
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/* TRUE if user has been authenticated */
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gboolean authenticated;
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/* TRUE if in user session */
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gboolean in_user_session;
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// FIXME: Token for secure access to this server
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};
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G_DEFINE_TYPE (Display, display, G_TYPE_OBJECT);
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static void start_greeter (Display *display);
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static void start_user_session (Display *display);
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Display *
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display_new (void)
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{
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return g_object_new (DISPLAY_TYPE, NULL);
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}
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static void
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session_watch_cb (GPid pid, gint status, gpointer data)
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{
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Display *display = data;
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if (WIFEXITED (status))
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g_debug ("Display exited with return value %d", WEXITSTATUS (status));
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else if (WIFSIGNALED (status))
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g_debug ("Display terminated with signal %d", WTERMSIG (status));
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display->priv->session_pid = 0;
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// FIXME: Check for respawn loops
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if (display->priv->authenticated && !display->priv->in_user_session)
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start_user_session (display);
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else
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start_greeter (display);
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}
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static void
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start_session (Display *display, const char *username, char * const argv[])
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{
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pid_t pid;
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struct passwd *user_info;
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g_return_if_fail (display->priv->session_pid == 0);
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errno = 0;
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user_info = getpwnam (username);
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if (!user_info)
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{
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g_warning ("Unable to get information on user %s: %s", username, strerror (errno));
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return;
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}
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pid = fork ();
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if (pid < 0)
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{
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g_warning ("Failed to fork session: %s", strerror (errno));
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return;
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}
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else if (pid > 0)
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{
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g_debug ("Child process started with PID %d", pid);
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display->priv->session_pid = pid;
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g_child_watch_add (display->priv->session_pid, session_watch_cb, display);
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return;
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}
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if (setgid (user_info->pw_gid) != 0)
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{
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g_warning ("Failed to set group ID: %s", strerror (errno));
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_exit(1);
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}
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// FIXME: Is there a risk of connecting to the process for a user in the given group and accessing memory?
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if (setuid (user_info->pw_uid) != 0)
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{
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g_warning ("Failed to set user ID: %s", strerror (errno));
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_exit(1);
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}
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if (chdir (user_info->pw_dir) != 0)
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g_warning ("Failed to change directory: %s", strerror (errno));
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/* Reset environment */
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// FIXME: Check these work
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clearenv ();
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setenv ("USER", user_info->pw_name, 1);
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setenv ("HOME", user_info->pw_dir, 1);
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setenv ("SHELL", user_info->pw_shell, 1);
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setenv ("HOME", user_info->pw_dir, 1);
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setenv ("DISPLAY", ":0", 1);
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execv (argv[0], argv);
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}
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static void
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start_user_session (Display *display)
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{
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char *argv[] = { "/usr/bin/gnome-terminal", NULL };
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display->priv->in_user_session = TRUE;
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start_session (display, display->priv->username, argv);
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}
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static void
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start_greeter (Display *display)
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{
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char *argv[] = { "/usr/bin/lightdm-greeter", NULL };
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display->priv->in_user_session = FALSE;
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g_free (display->priv->username);
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display->priv->username = NULL;
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start_session (display, "gdm", argv);
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}
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static int
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pam_conv_cb (int num_msg, const struct pam_message **msg,
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struct pam_response **resp, void *app_data)
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{
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Display *display = app_data;
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gpointer response;
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/* Respond to d-bus query with messages */
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dbus_g_method_return (display->priv->dbus_context, 666); // ACTIONS
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display->priv->dbus_context = NULL;
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/* Wait for responses */
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response = g_async_queue_pop (display->priv->authentication_response_queue);
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/* Fill responses */
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// ...
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return 0;
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}
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static gpointer
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authenticate_cb (gpointer data)
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{
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Display *display = data;
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struct pam_conv conversation = { pam_conv_cb, display };
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int result;
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pam_start ("check_pass", display->priv->username, &conversation, &display->priv->pam_handle);
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result = pam_authenticate (display->priv->pam_handle, 0);
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/* Thread complete */
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g_thread_join (display->priv->authentication_thread);
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display->priv->authentication_thread = NULL;
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g_async_queue_unref (display->priv->authentication_response_queue);
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display->priv->authentication_response_queue = NULL;
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/* Respond to D-Bus request */
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dbus_g_method_return (display->priv->dbus_context, 888); // FINISHED
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display->priv->dbus_context = NULL;
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return NULL;
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}
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gboolean
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display_start_authentication (Display *display, const char *username, DBusGMethodInvocation *context)
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{
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GError *error = NULL;
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// FIXME: Only allow calls from the greeter
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g_return_val_if_fail (display->priv->authentication_thread != NULL, FALSE);
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/* Store authentication request and D-Bus request to respond to */
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g_free (display->priv->username);
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display->priv->username = g_strdup (username);
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display->priv->dbus_context = context;
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/* Start thread */
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display->priv->authentication_response_queue = g_async_queue_new ();
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display->priv->authentication_thread = g_thread_create (authenticate_cb, display, TRUE, &error);
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if (!display->priv->authentication_thread)
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{
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g_warning ("Failed to start authentication thread: %s", error->message);
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display->priv->dbus_context = NULL;
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return FALSE;
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}
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g_clear_error (&error);
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return TRUE;
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}
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gboolean
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display_continue_authentication (Display *display, int data, DBusGMethodInvocation *context)
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{
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g_return_val_if_fail (display->priv->authentication_thread == NULL, FALSE);
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g_return_val_if_fail (display->priv->dbus_context != NULL, FALSE);
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// FIXME: Only allow calls from the greeter
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/* Push onto queue and store request to respond to */
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display->priv->dbus_context = context;
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g_async_queue_push (display->priv->authentication_response_queue, GINT_TO_POINTER (data));
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return TRUE;
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}
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static void
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xserver_watch_cb (GPid pid, gint status, gpointer data)
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{
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Display *display = data;
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if (WIFEXITED (status))
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g_debug ("Display exited with return value %d", WEXITSTATUS (status));
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else if (WIFSIGNALED (status))
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g_debug ("Display terminated with signal %d", WTERMSIG (status));
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display->priv->xserver_pid = 0;
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g_signal_emit (display, signals[EXITED], 0);
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}
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static void
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display_init (Display *display)
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{
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GError *error = NULL;
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char *argv[] = { "/usr/bin/X", ":0", NULL };
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char *env[] = { NULL };
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gboolean result;
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display->priv = G_TYPE_INSTANCE_GET_PRIVATE (display, DISPLAY_TYPE, DisplayPrivate);
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result = g_spawn_async (NULL, /* Working directory */
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argv,
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env,
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G_SPAWN_DO_NOT_REAP_CHILD,
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NULL, NULL,
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&display->priv->xserver_pid,
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&error);
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if (!result)
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g_warning ("Unable to create display: %s", error->message);
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else
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g_child_watch_add (display->priv->xserver_pid, xserver_watch_cb, display);
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g_clear_error (&error);
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/* TODO: Do autologin if this is requested */
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start_greeter (display);
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}
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static void
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display_class_init (DisplayClass *klass)
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{
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g_type_class_add_private (klass, sizeof (DisplayPrivate));
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signals[EXITED] =
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g_signal_new ("exited",
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G_TYPE_FROM_CLASS (klass),
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G_SIGNAL_RUN_LAST,
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G_STRUCT_OFFSET (DisplayClass, exited),
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NULL, NULL,
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g_cclosure_marshal_VOID__VOID,
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G_TYPE_NONE, 0);
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}
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