/*
 * * Copyright (C) 2009-2011 Ali <aliov@xfce.org>
 *
 * Licensed under the GNU General Public License Version 2
 *
 * 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#ifdef HAVE_SYS_SYSCTL_H
#include <sys/sysctl.h>
#endif
#ifdef HAVE_SYS_USER_H
#include <sys/user.h>
#endif

#if defined(__FreeBSD__)
#include <sys/stat.h>
#elif defined(__SVR4) && defined(__sun)
#include <fcntl.h>
#include <procfs.h>
#endif

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#include "xfpm-polkit.h"
#include "xfpm-debug.h"

#include "xfpm-common.h"

static void xfpm_polkit_finalize   (GObject *object);

struct XfpmPolkitPrivate
{
  GDBusConnection   *bus;

#ifdef HAVE_POLKIT
  GDBusProxy        *proxy;
  GVariant          *subject;
  GVariant          *details;

  gulong             destroy_id;
  gboolean           subject_valid;
#endif
};

enum
{
  AUTH_CHANGED,
  LAST_SIGNAL
};

static guint signals [LAST_SIGNAL] = { 0 };

G_DEFINE_TYPE_WITH_PRIVATE (XfpmPolkit, xfpm_polkit, G_TYPE_OBJECT)

#ifdef HAVE_POLKIT
#if defined(__FreeBSD__)
/**
 * Taken from polkitunixprocess.c code to get process start
 * time from pid.
 *
 * Copyright (C) 2008 Red Hat, Inc.
 *
 **/
static gboolean
get_kinfo_proc (pid_t pid, struct kinfo_proc *p)
{
  int mib[4];
  size_t len;

  len = 4;
  sysctlnametomib ("kern.proc.pid", mib, &len);

  len = sizeof (struct kinfo_proc);
  mib[3] = pid;

  if (sysctl (mib, 4, p, &len, NULL, 0) == -1)
    return FALSE;

  return TRUE;
}
#endif /*if defined(__FreeBSD__)*/

static guint64
get_start_time_for_pid (pid_t pid)
{
  guint64 start_time = 0;
#if defined(__linux)
  gchar *filename;
  gchar *contents;
  size_t length;
  gchar **tokens;
  guint num_tokens;
  gchar *p;
  gchar *endp;

  start_time = 0;
  contents = NULL;

  filename = g_strdup_printf ("/proc/%d/stat", pid);

  if (!g_file_get_contents (filename, &contents, &length, NULL))
    goto out;

  /* start time is the token at index 19 after the '(process name)' entry - since only this
   * field can contain the ')' character, search backwards for this to avoid malicious
   * processes trying to fool us
   */
  p = strrchr (contents, ')');
  if (p == NULL)
  {
    goto out;
  }

  p += 2; /* skip ') ' */

  if (p - contents >= (int) length)
  {
    g_warning ("Error parsing file %s", filename);
    goto out;
  }

  tokens = g_strsplit (p, " ", 0);

  num_tokens = g_strv_length (tokens);

  if (num_tokens < 20)
  {
    g_warning ("Error parsing file %s", filename);
    goto out;
  }

  start_time = strtoull (tokens[19], &endp, 10);
  if (endp == tokens[19])
  {
    g_warning ("Error parsing file %s", filename);
    goto out;
  }
  g_strfreev (tokens);

 out:
  g_free (filename);
  g_free (contents);

#elif defined(__FreeBSD__)

  struct kinfo_proc p;

  start_time = 0;

  if (! get_kinfo_proc (pid, &p))
  {
    g_warning ("Error obtaining start time for %d (%s)",
               (gint) pid,
               g_strerror (errno));
    goto out;
  }

  start_time = (guint64) p.ki_start.tv_sec;

out:
#elif defined(__SVR4) && defined(__sun)

  psinfo_t p;
  gchar *filename;
  int fd;

  start_time = 0;

  filename = g_strdup_printf ("/proc/%d/psinfo", (int) pid);
  if ((fd = open (filename, O_RDONLY)) < 0)
  {
    g_warning ("Error opening %s (%s)",
               filename,
               g_strerror (errno));
    goto out;
  }
  if (read (fd, &p, sizeof (p)) != sizeof (p))
  {
    g_warning ("Error reading %s",
               filename);
    close (fd);
    goto out;
  }
  start_time = (guint64) p.pr_start.tv_sec;
  close(fd);
out:
  g_free (filename);
#endif

  return start_time;
}
#endif /*HAVE_POLKIT*/


#ifdef HAVE_POLKIT
static void
xfpm_polkit_free_data (XfpmPolkit *polkit)
{
  g_assert (polkit->priv->subject_valid);

  XFPM_DEBUG ("Destroying Polkit data");

  g_variant_unref (polkit->priv->details);
  g_variant_unref (polkit->priv->subject);

  polkit->priv->details      = NULL;
  polkit->priv->subject      = NULL;

  polkit->priv->destroy_id = 0;
  polkit->priv->subject_valid = FALSE;
}

static gboolean
xfpm_polkit_free_data_cb (gpointer user_data)
{
  XfpmPolkit *polkit;

  polkit = XFPM_POLKIT (user_data);
  xfpm_polkit_free_data (polkit);

  return FALSE;
}

static void
xfpm_polkit_init_data (XfpmPolkit *polkit)
{
  gint pid;
  guint64 start_time;
  GVariantBuilder builder;
  const gchar *subject_kind = NULL;

  if (polkit->priv->subject_valid)
    return;

  g_variant_builder_init (&builder, G_VARIANT_TYPE ("a{sv}"));

  pid = getpid ();

  start_time = get_start_time_for_pid (pid);

  if ( G_LIKELY (start_time != 0 ) )
  {
    GVariant *var;

    subject_kind = "unix-process";

    var = g_variant_new ("u", (guint32)pid);
    g_variant_builder_add (&builder, "{sv}", "pid", var);

    var = g_variant_new ("t", start_time);
    g_variant_builder_add (&builder, "{sv}", "start-time", var);

    XFPM_DEBUG ("Using unix session polkit subject");
  }
  else
  {
    g_warning ("Unable to create polkit subject");
  }

  polkit->priv->subject =
  g_variant_ref_sink (g_variant_new ("(sa{sv})",
                      subject_kind,
                      &builder));

  /**
   * Polkit details, will leave it empty.
   **/
  g_variant_builder_init (&builder, G_VARIANT_TYPE ("a{ss}"));
  polkit->priv->details = g_variant_ref_sink (g_variant_new ("a{ss}",
                                              &builder));

  /*Clean these data after 1 minute*/
  polkit->priv->destroy_id = g_timeout_add_seconds (60, xfpm_polkit_free_data_cb, polkit);

  polkit->priv->subject_valid = TRUE;
}
#endif /*HAVE_POLKIT*/

static gboolean
xfpm_polkit_check_auth_intern (XfpmPolkit *polkit, const gchar *action_id)
{
#ifdef HAVE_POLKIT
  GError *error = NULL;
  gboolean is_authorized = FALSE;
  GVariant *var;

  /**
   * <method name="CheckAuthorization">
   *   <arg type="(sa{sv})" name="subject" direction="in"/>
   *   <arg type="s" name="action_id" direction="in"/>
   *   <arg type="a{ss}" name="details" direction="in"/>
   *   <arg type="u" name="flags" direction="in"/>
   *   <arg type="s" name="cancellation_id" direction="in"/>
   *   <arg type="(bba{ss})" name="result" direction="out"/>
   * </method>
   *
   **/

  g_return_val_if_fail (polkit->priv->proxy != NULL, FALSE);
  g_return_val_if_fail (polkit->priv->subject_valid, FALSE);

  var = g_variant_new ("(@(sa{sv})s@a{ss}us)",
                       polkit->priv->subject,
                       action_id,
                       polkit->priv->details,
                       0,
                       "");

  XFPM_DEBUG ("polkit request: %s", g_variant_print (var, TRUE));

  var = g_dbus_proxy_call_sync (polkit->priv->proxy, "CheckAuthorization",
                                var,
                                G_DBUS_CALL_FLAGS_NONE,
                                -1, NULL,
                                &error);

  if ( G_LIKELY (var) )
  {
    g_variant_get (var, "((bba{ss}))",
                   &is_authorized, NULL, NULL);

    g_variant_unref (var);
  }
  else if ( error )
  {
    g_warning ("'CheckAuthorization' failed with %s", error->message);
    g_error_free (error);
  }

  XFPM_DEBUG ("Action=%s is authorized=%s", action_id, xfpm_bool_to_string (is_authorized));

  return is_authorized;
#endif /*HAVE_POLKIT*/
  return TRUE;
}

#ifdef HAVE_POLKIT
static void
xfpm_polkit_changed_cb (GDBusProxy *proxy,
                        gchar      *sender_name,
                        gchar      *signal_name,
                        GVariant   *parameters,
                        XfpmPolkit *polkit)
{
  if (g_strcmp0 (signal_name, "Changed") == 0)
  {
    XFPM_DEBUG ("Auth changed");
    g_signal_emit (G_OBJECT (polkit), signals [AUTH_CHANGED], 0);
  }
}
#endif

static void
xfpm_polkit_class_init (XfpmPolkitClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  object_class->finalize = xfpm_polkit_finalize;

  signals [AUTH_CHANGED] =
      g_signal_new ("auth-changed",
                    XFPM_TYPE_POLKIT,
                    G_SIGNAL_RUN_LAST,
                    G_STRUCT_OFFSET(XfpmPolkitClass, auth_changed),
                    NULL, NULL,
                    g_cclosure_marshal_VOID__VOID,
                    G_TYPE_NONE, 0, G_TYPE_NONE);
}

static void
xfpm_polkit_init (XfpmPolkit *polkit)
{
  GError *error = NULL;

  polkit->priv = xfpm_polkit_get_instance_private (polkit);

#ifdef HAVE_POLKIT
  polkit->priv->destroy_id   = 0;
  polkit->priv->subject_valid   = FALSE;
  polkit->priv->proxy        = NULL;
  polkit->priv->subject      = NULL;
  polkit->priv->details      = NULL;
#endif /*HAVE_POLKIT*/

  polkit->priv->bus = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, &error);

  if ( error )
  {
    g_critical ("Error getting system bus connection : %s", error->message);
    g_error_free (error);
    goto out;
  }

#ifdef HAVE_POLKIT
  polkit->priv->proxy =
  g_dbus_proxy_new_sync (polkit->priv->bus,
                         G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES,
                         NULL,
                         "org.freedesktop.PolicyKit1",
                         "/org/freedesktop/PolicyKit1/Authority",
                         "org.freedesktop.PolicyKit1.Authority",
                         NULL,
                         NULL);

  if (G_LIKELY (polkit->priv->proxy) )
  {
    g_signal_connect (polkit->priv->proxy, "g-signal",
    G_CALLBACK (xfpm_polkit_changed_cb), polkit);
  }
  else
  {
    g_warning ("Failed to create proxy for 'org.freedesktop.PolicyKit1'");
  }
#endif /*HAVE_POLKIT*/

out:
  ;
}

static void
xfpm_polkit_finalize (GObject *object)
{
  XfpmPolkit *polkit;

  polkit = XFPM_POLKIT (object);

#ifdef HAVE_POLKIT
  if ( polkit->priv->proxy )
  {
    g_signal_handlers_disconnect_by_func (polkit->priv->proxy,
                                          G_CALLBACK (xfpm_polkit_changed_cb), polkit);
    g_object_unref (polkit->priv->proxy);
  }

  if ( polkit->priv->subject_valid )
  {
    xfpm_polkit_free_data (polkit);
    if (polkit->priv->destroy_id != 0 )
      g_source_remove (polkit->priv->destroy_id);
  }
#endif /*HAVE_POLKIT*/


  if ( polkit->priv->bus )
    g_object_unref (polkit->priv->bus);

  G_OBJECT_CLASS (xfpm_polkit_parent_class)->finalize (object);
}

XfpmPolkit *
xfpm_polkit_get (void)
{
  static gpointer xfpm_polkit_obj = NULL;

  if ( G_LIKELY (xfpm_polkit_obj) )
  {
    g_object_ref (xfpm_polkit_obj);
  }
  else
  {
    xfpm_polkit_obj = g_object_new (XFPM_TYPE_POLKIT, NULL);
    g_object_add_weak_pointer (xfpm_polkit_obj, &xfpm_polkit_obj);
  }

  return XFPM_POLKIT (xfpm_polkit_obj);
}

gboolean
xfpm_polkit_check_auth (XfpmPolkit *polkit, const gchar *action_id)
{
#ifdef HAVE_POLKIT
  xfpm_polkit_init_data (polkit);
#endif
  return xfpm_polkit_check_auth_intern (polkit, action_id);
}
