gnupg/kbx/keyboxd.c

/* keyboxd.c  -  The GnuPG Keybox Daemon
 * Copyright (C) 2000-2020 Free Software Foundation, Inc.
 * Copyright (C) 2000-2019 Werner Koch
 * Copyright (C) 2015-2020 g10 Code GmbH
 *
 * This file is part of GnuPG.
 *
 * GnuPG 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 version.
 *
 * GnuPG 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, see <https://www.gnu.org/licenses/>.
 * SPDX-License-Identifier: GPL-3.0+
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#ifdef HAVE_W32_SYSTEM
# ifndef WINVER
#  define WINVER 0x0500  /* Same as in common/sysutils.c */
# endif
# include <winsock2.h>
#else /*!HAVE_W32_SYSTEM*/
# include <sys/socket.h>
# include <sys/un.h>
#endif /*!HAVE_W32_SYSTEM*/
#include <unistd.h>
#ifdef HAVE_SIGNAL_H
# include <signal.h>
#endif
#include <npth.h>

#define INCLUDED_BY_MAIN_MODULE 1
#define GNUPG_COMMON_NEED_AFLOCAL
#include "keyboxd.h"
#include <assuan.h> /* Malloc hooks and socket wrappers. */

#include "../common/i18n.h"
#include "../common/sysutils.h"
#include "../common/asshelp.h"
#include "../common/init.h"
#include "../common/gc-opt-flags.h"
#include "../common/exechelp.h"
#include "../common/comopt.h"
#include "frontend.h"


/* Urrgs: Put this into a separate header - but it needs assuan.h first.  */
extern int kbxd_assuan_log_monitor (assuan_context_t ctx, unsigned int cat,
                                    const char *msg);


enum cmd_and_opt_values
  {
    aNull = 0,
    oQuiet	  = 'q',
    oVerbose	  = 'v',

    oNoVerbose = 500,
    aGPGConfList,
    aGPGConfTest,
    oOptions,
    oDebug,
    oDebugAll,
    oDebugWait,
    oNoGreeting,
    oNoOptions,
    oHomedir,
    oNoDetach,
    oStealSocket,
    oLogFile,
    oServer,
    oDaemon,
    oFakedSystemTime,
    oListenBacklog,
    oDisableCheckOwnSocket,

    oDummy
  };


static gpgrt_opt_t opts[] = {
  ARGPARSE_c (aGPGConfList, "gpgconf-list", "@"),
  ARGPARSE_c (aGPGConfTest, "gpgconf-test", "@"),

  ARGPARSE_header (NULL, N_("Options used for startup")),

  ARGPARSE_s_n (oDaemon,  "daemon", N_("run in daemon mode (background)")),
  ARGPARSE_s_n (oServer,  "server", N_("run in server mode (foreground)")),
  ARGPARSE_s_n (oNoDetach,  "no-detach", N_("do not detach from the console")),
  ARGPARSE_s_n (oStealSocket, "steal-socket", "@"),
  ARGPARSE_s_s (oHomedir,    "homedir",      "@"),
  ARGPARSE_conffile (oOptions, "options", N_("|FILE|read options from FILE")),

  ARGPARSE_header ("Monitor", N_("Options controlling the diagnostic output")),

  ARGPARSE_s_n (oVerbose, "verbose", N_("verbose")),
  ARGPARSE_s_n (oQuiet,	  "quiet",     N_("be somewhat more quiet")),
  ARGPARSE_s_s (oDebug,	    "debug",      "@"),
  ARGPARSE_s_n (oDebugAll,  "debug-all",  "@"),
  ARGPARSE_s_i (oDebugWait, "debug-wait", "@"),
  ARGPARSE_s_s (oLogFile,   "log-file",  N_("use a log file for the server")),

  ARGPARSE_header ("Configuration",
                   N_("Options controlling the configuration")),

  ARGPARSE_s_n (oDisableCheckOwnSocket, "disable-check-own-socket", "@"),
  ARGPARSE_s_s (oFakedSystemTime, "faked-system-time", "@"),
  ARGPARSE_s_i (oListenBacklog, "listen-backlog", "@"),

  ARGPARSE_end () /* End of list */
};


/* The list of supported debug flags.  */
static struct debug_flags_s debug_flags [] =
  {
    { DBG_MPI_VALUE    , "mpi"     },
    { DBG_CRYPTO_VALUE , "crypto"  },
    { DBG_MEMORY_VALUE , "memory"  },
    { DBG_CACHE_VALUE  , "cache"   },
    { DBG_MEMSTAT_VALUE, "memstat" },
    { DBG_HASHING_VALUE, "hashing" },
    { DBG_IPC_VALUE    , "ipc"     },
    { DBG_CLOCK_VALUE  , "clock"   },
    { DBG_LOOKUP_VALUE , "lookup"  },
    { 77, NULL } /* 77 := Do not exit on "help" or "?".  */
  };

/* CHECK_OWN_SOCKET_INTERVAL defines how often we check our own socket
 * in standard socket mode.  If that value is 0 we don't check at all.
 * Values is in seconds. */
#define CHECK_OWN_SOCKET_INTERVAL  (60)
/* CHECK_PROBLEMS_INTERVAL defines how often we check the existence of
 * homedir.  Value is in seconds.  */
#define CHECK_PROBLEMS_INTERVAL     (4)

/* The list of open file descriptors at startup.  Note that this list
 * has been allocated using the standard malloc.  */
#ifndef HAVE_W32_SYSTEM
static int *startup_fd_list;
#endif

/* The signal mask at startup and a flag telling whether it is valid.  */
#ifdef HAVE_SIGPROCMASK
static sigset_t startup_signal_mask;
static int startup_signal_mask_valid;
#endif

/* Flag to indicate that a shutdown was requested.  */
static int shutdown_pending;

/* Flag indicating to start the daemon even if one already runs.  */
static int steal_socket;

/* Flag to monitor problems.  */
static int problem_detected;
#define KEYBOXD_PROBLEM_SOCKET_TAKEOVER (1 << 0)
#define KEYBOXD_PROBLEM_HOMEDIR_REMOVED (1 << 1)

/* Flag to indicate that we shall not watch our own socket. */
static int disable_check_own_socket;

/* Flag to inhibit socket removal in cleanup.  */
static int inhibit_socket_removal;

/* Name of the communication socket used for client requests.  */
static char *socket_name;

/* We need to keep track of the server's nonces (these are dummies for
 * POSIX systems). */
static assuan_sock_nonce_t socket_nonce;

/* Value for the listen() backlog argument.  We use the same value for
 * all sockets - 64 is on current Linux half of the default maximum.
 * Let's try this as default.  Change at runtime with --listen-backlog.  */
static int listen_backlog = 64;

#ifdef HAVE_W32_SYSTEM
/* The event to break the select call.  */
static HANDLE the_event2;
#elif defined(HAVE_PSELECT_NO_EINTR)
/* An FD to break the select call.  */
static int event_pipe_fd;
#else
/* PID of the main thread.  */
static pid_t main_thread_pid;
#endif

/* Name of a config file, which will be reread on a HUP if it is not NULL. */
static char *config_filename;

/* Keep track of the current log file so that we can avoid updating
 * the log file after a SIGHUP if it didn't changed.  Malloced. */
static char *current_logfile;

/* Number of active connections.  */
static int active_connections;

/* This object is used to dispatch progress messages from Libgcrypt to
 * the right thread.  Given that we will have at max only a few dozen
 * connections at a time, using a linked list is the easiest way to
 * handle this. */
struct progress_dispatch_s
{
  struct progress_dispatch_s *next;
  /* The control object of the connection.  If this is NULL no
   * connection is associated with this item and it is free for reuse
   * by new connections.  */
  ctrl_t ctrl;

  /* The thread id of (npth_self) of the connection.  */
  npth_t tid;

  /* The callback set by the connection.  This is similar to the
   * Libgcrypt callback but with the control object passed as the
   * first argument.  */
  void (*cb)(ctrl_t ctrl,
             const char *what, int printchar,
             int current, int total);
};
struct progress_dispatch_s *progress_dispatch_list;




/*
 * Local prototypes.
 */

static char *create_socket_name (char *standard_name, int with_homedir);
static gnupg_fd_t create_server_socket (char *name, int cygwin,
                                        assuan_sock_nonce_t *nonce);
static void create_directories (void);

static void kbxd_libgcrypt_progress_cb (void *data, const char *what,
                                        int printchar,
                                        int current, int total);
static void kbxd_init_default_ctrl (ctrl_t ctrl);
static void kbxd_deinit_default_ctrl (ctrl_t ctrl);

static void handle_connections (gnupg_fd_t listen_fd);
static int check_for_running_kbxd (int silent);
#if CHECK_OWN_SOCKET_INTERVAL > 0
static void *check_own_socket_thread (void *arg);
#endif
static void *check_others_thread (void *arg);

/*
 * Functions.
 */

/* Allocate a string describing a library version by calling a GETFNC.
 * This function is expected to be called only once.  GETFNC is
 * expected to have a semantic like gcry_check_version ().  */
static char *
make_libversion (const char *libname, const char *(*getfnc)(const char*))
{
  return xstrconcat (libname, " ", getfnc (NULL), NULL);
}


/* Return strings describing this program.  The case values are
 * described in Libgpg-error.  The values here override the default
 * values given by strusage.  */
static const char *
my_strusage (int level)
{
  static char *ver_gcry;
  const char *p;

  switch (level)
    {
    case  9: p = "GPL-3.0-or-later"; break;
    case 11: p = "keyboxd (@GNUPG@)";
      break;
    case 13: p = VERSION; break;
    case 14: p = GNUPG_DEF_COPYRIGHT_LINE; break;
    case 17: p = PRINTABLE_OS_NAME; break;
      /* TRANSLATORS: @EMAIL@ will get replaced by the actual bug
         reporting address.  This is so that we can change the
         reporting address without breaking the translations.  */
    case 19: p = _("Please report bugs to <@EMAIL@>.\n"); break;

    case 20:
      if (!ver_gcry)
        ver_gcry = make_libversion ("libgcrypt", gcry_check_version);
      p = ver_gcry;
      break;

    case 1:
    case 40: p =  _("Usage: keyboxd [options] (-h for help)");
      break;
    case 41: p =  _("Syntax: keyboxd [options] [command [args]]\n"
                    "Public key management for @GNUPG@\n");
    break;

    default: p = NULL;
    }
  return p;
}



/* Setup the debugging.  Note that we don't fail here, because it is
 * important to keep keyboxd running even after re-reading the options
 * due to a SIGHUP. */
static void
set_debug (void)
{
  if (opt.debug && !opt.verbose)
    opt.verbose = 1;
  if (opt.debug && opt.quiet)
    opt.quiet = 0;

  if (opt.debug & DBG_MPI_VALUE)
    gcry_control (GCRYCTL_SET_DEBUG_FLAGS, 2);
  if (opt.debug & DBG_CRYPTO_VALUE )
    gcry_control (GCRYCTL_SET_DEBUG_FLAGS, 1);
  gcry_control (GCRYCTL_SET_VERBOSITY, (int)opt.verbose);

  if (opt.debug)
    parse_debug_flag (NULL, &opt.debug, debug_flags);
}


/* Helper for cleanup to remove one socket with NAME.  */
static void
remove_socket (char *name)
{
  if (name && *name)
    {
      gnupg_remove (name);
      *name = 0;
    }
}


/* Cleanup code for this program.  This is either called has an atexit
   handler or directly.  */
static void
cleanup (void)
{
  static int done;

  if (done)
    return;
  done = 1;
  if (!inhibit_socket_removal)
    remove_socket (socket_name);
}


/* Handle options which are allowed to be reset after program start.
 * Return true when the current option in PARGS could be handled and
 * false if not.  As a special feature, passing a value of NULL for
 * PARGS, resets the options to the default.  REREAD should be set
 * true if it is not the initial option parsing. */
static int
parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
{
  if (!pargs)
    { /* reset mode */
      opt.quiet = 0;
      opt.verbose = 0;
      opt.debug = 0;
      disable_check_own_socket = 0;
      return 1;
    }

  switch (pargs->r_opt)
    {
    case oQuiet: opt.quiet = 1; break;
    case oVerbose: opt.verbose++; break;

    case oDebug:
      parse_debug_flag (pargs->r.ret_str, &opt.debug, debug_flags);
      break;
    case oDebugAll: opt.debug = ~0; break;

    case oLogFile:
      if (!reread)
        return 0; /* not handled */
      if (!current_logfile || !pargs->r.ret_str
          || strcmp (current_logfile, pargs->r.ret_str))
        {
          log_set_file (pargs->r.ret_str);
          xfree (current_logfile);
          current_logfile = xtrystrdup (pargs->r.ret_str);
        }
      break;

    case oDisableCheckOwnSocket: disable_check_own_socket = 1; break;

    default:
      return 0; /* not handled */
    }

  return 1; /* handled */
}


/* Fixup some options after all have been processed.  */
static void
finalize_rereadable_options (void)
{
}


static void
thread_init_once (void)
{
  static int npth_initialized = 0;

  if (!npth_initialized)
    {
      npth_initialized++;
      npth_init ();
    }
  gpgrt_set_syscall_clamp (npth_unprotect, npth_protect);
  /* Now that we have set the syscall clamp we need to tell Libgcrypt
   * that it should get them from libgpg-error.  Note that Libgcrypt
   * has already been initialized but at that point nPth was not
   * initialized and thus Libgcrypt could not set its system call
   * clamp.  */
  gcry_control (GCRYCTL_REINIT_SYSCALL_CLAMP, 0, 0);
  assuan_control (ASSUAN_CONTROL_REINIT_SYSCALL_CLAMP, NULL);
}


static void
initialize_modules (void)
{
  thread_init_once ();
}


/* The main entry point.  */
int
main (int argc, char **argv )
{
  gpgrt_argparse_t pargs;
  int orig_argc;
  char **orig_argv;
  char *last_configname = NULL;
  char *configname = NULL;
  int debug_argparser = 0;
  int pipe_server = 0;
  int is_daemon = 0;
  int nodetach = 0;
  char *logfile = NULL;
  int gpgconf_list = 0;
  int debug_wait = 0;
  struct assuan_malloc_hooks malloc_hooks;

  early_system_init ();

  /* Before we do anything else we save the list of currently open
   * file descriptors and the signal mask.  This info is required to
   * do the exec call properly.  We don't need it on Windows.  */
#ifndef HAVE_W32_SYSTEM
  startup_fd_list = get_all_open_fds ();
#endif /*!HAVE_W32_SYSTEM*/
#ifdef HAVE_SIGPROCMASK
  if (!sigprocmask (SIG_UNBLOCK, NULL, &startup_signal_mask))
    startup_signal_mask_valid = 1;
#endif /*HAVE_SIGPROCMASK*/

  /* Set program name etc.  */
  gpgrt_set_strusage (my_strusage);
  log_set_prefix ("keyboxd", GPGRT_LOG_WITH_PREFIX|GPGRT_LOG_WITH_PID);

  /* Make sure that our subsystems are ready.  */
  i18n_init ();
  init_common_subsystems (&argc, &argv);
  gcry_control (GCRYCTL_DISABLE_SECMEM, 0);

  malloc_hooks.malloc = gcry_malloc;
  malloc_hooks.realloc = gcry_realloc;
  malloc_hooks.free = gcry_free;
  assuan_set_malloc_hooks (&malloc_hooks);
  assuan_set_gpg_err_source (GPG_ERR_SOURCE_DEFAULT);
  assuan_sock_init ();
  setup_libassuan_logging (&opt.debug, kbxd_assuan_log_monitor);

  setup_libgcrypt_logging ();
  gcry_set_progress_handler (kbxd_libgcrypt_progress_cb, NULL);

  /* Set default options.  */
  parse_rereadable_options (NULL, 0); /* Reset them to default values. */

  /* Check whether we have a config file on the commandline */
  orig_argc = argc;
  orig_argv = argv;
  pargs.argc = &argc;
  pargs.argv = &argv;
  pargs.flags= (ARGPARSE_FLAG_KEEP | ARGPARSE_FLAG_NOVERSION);
  while (gpgrt_argparse (NULL, &pargs, opts))
    {
      switch (pargs.r_opt)
        {
        case oDebug:
        case oDebugAll:
          debug_argparser++;
          break;

        case oHomedir:
          gnupg_set_homedir (pargs.r.ret_str);
          break;
        }
    }
  /* Reset the flags.  */
  pargs.flags &= ~(ARGPARSE_FLAG_KEEP | ARGPARSE_FLAG_NOVERSION);

  /* The configuration directories for use by gpgrt_argparser.  */
  gpgrt_set_confdir (GPGRT_CONFDIR_SYS, gnupg_sysconfdir ());
  gpgrt_set_confdir (GPGRT_CONFDIR_USER, gnupg_homedir ());

  argc = orig_argc;
  argv = orig_argv;
  pargs.argc = &argc;
  pargs.argv = &argv;
  pargs.flags |=  (ARGPARSE_FLAG_RESET
                   | ARGPARSE_FLAG_KEEP
                   | ARGPARSE_FLAG_SYS
                   | ARGPARSE_FLAG_USER);

  while (gpgrt_argparser (&pargs, opts, "keyboxd" EXTSEP_S "conf"))
    {
      if (pargs.r_opt == ARGPARSE_CONFFILE)
        {
          if (debug_argparser)
            log_info (_("reading options from '%s'\n"),
                      pargs.r_type? pargs.r.ret_str: "[cmdline]");
          if (pargs.r_type)
            {
              xfree (last_configname);
              last_configname = xstrdup (pargs.r.ret_str);
              configname = last_configname;
            }
          else
            configname = NULL;
          continue;
        }
      if (parse_rereadable_options (&pargs, 0))
        continue; /* Already handled */
      switch (pargs.r_opt)
        {
        case aGPGConfList: gpgconf_list = 1; break;
        case aGPGConfTest: gpgconf_list = 2; break;
        case oDebugWait: debug_wait = pargs.r.ret_int; break;
        case oNoGreeting: /* Dummy option.  */ break;
        case oNoVerbose: opt.verbose = 0; break;
        case oNoOptions: break; /* no-options */
        case oHomedir: gnupg_set_homedir (pargs.r.ret_str); break;
        case oNoDetach: nodetach = 1; break;
        case oStealSocket: steal_socket = 1; break;
        case oLogFile: logfile = pargs.r.ret_str; break;
        case oServer: pipe_server = 1; break;
        case oDaemon: is_daemon = 1; break;
        case oFakedSystemTime:
          {
            time_t faked_time = isotime2epoch (pargs.r.ret_str);
            if (faked_time == (time_t)(-1))
              faked_time = (time_t)strtoul (pargs.r.ret_str, NULL, 10);
            gnupg_set_time (faked_time, 0);
          }
          break;

        case oListenBacklog:
          listen_backlog = pargs.r.ret_int;
          break;

        default:
          if (configname)
            pargs.err = ARGPARSE_PRINT_WARNING;
          else
            pargs.err = ARGPARSE_PRINT_ERROR;
          break;
	}
    }
  gpgrt_argparse (NULL, &pargs, NULL);

  if (!last_configname)
    config_filename = gpgrt_fnameconcat (gnupg_homedir (),
                                             "keyboxd" EXTSEP_S "conf",
                                             NULL);
  else
    {
      config_filename = last_configname;
      last_configname = NULL;
    }


  if (log_get_errorcount(0))
    exit (2);

    /* Get a default log file from common.conf.  */
  if (!logfile && !parse_comopt (GNUPG_MODULE_NAME_KEYBOXD, debug_argparser))
    {
      logfile = comopt.logfile;
      comopt.logfile = NULL;
    }


  finalize_rereadable_options ();

  /* Print a warning if an argument looks like an option.  */
  if (!opt.quiet && !(pargs.flags & ARGPARSE_FLAG_STOP_SEEN))
    {
      int i;

      for (i=0; i < argc; i++)
        if (argv[i][0] == '-' && argv[i][1] == '-')
          log_info (_("Note: '%s' is not considered an option\n"), argv[i]);
    }

#ifdef ENABLE_NLS
  /* keyboxd usually does not output any messages because it runs in
   * the background.  For log files it is acceptable to have messages
   * always encoded in utf-8.  We switch here to utf-8, so that
   * commands like --help still give native messages.  It is far
   * easier to switch only once instead of for every message and it
   * actually helps when more then one thread is active (avoids an
   * extra copy step). */
  bind_textdomain_codeset (PACKAGE_GT, "UTF-8");
#endif

  if (!pipe_server && !is_daemon && !gpgconf_list)
    {
     /* We have been called without any command and thus we merely
      * check whether an instance of us is already running.  We do
      * this right here so that we don't clobber a logfile with this
      * check but print the status directly to stderr.  */
      opt.debug = 0;
      set_debug ();
      check_for_running_kbxd (0);
      kbxd_exit (0);
    }

  set_debug ();

  if (atexit (cleanup))
    {
      log_error ("atexit failed\n");
      cleanup ();
      exit (1);
    }

  /* Try to create missing directories. */
  create_directories ();

  if (debug_wait && pipe_server)
    {
      thread_init_once ();
      log_debug ("waiting for debugger - my pid is %u .....\n",
                 (unsigned int)getpid());
      gnupg_sleep (debug_wait);
      log_debug ("... okay\n");
    }

  if (gpgconf_list == 2)
    kbxd_exit (0);
  else if (gpgconf_list)
    {
      kbxd_exit (0);
    }

  /* Now start with logging to a file if this is desired. */
  if (logfile)
    {
      log_set_file (logfile);
      log_set_prefix (NULL, (GPGRT_LOG_WITH_PREFIX
                             | GPGRT_LOG_WITH_TIME
                             | GPGRT_LOG_WITH_PID));
      current_logfile = xstrdup (logfile);
    }

  if (pipe_server)
    {
      /* This is the simple pipe based server */
      ctrl_t ctrl;

      initialize_modules ();

      ctrl = xtrycalloc (1, sizeof *ctrl);
      if (!ctrl)
        {
          log_error ("error allocating connection control data: %s\n",
                     strerror (errno) );
          kbxd_exit (1);
        }
      kbxd_init_default_ctrl (ctrl);

      /* kbxd_set_database (ctrl, "pubring.kbx", 0); */
      kbxd_set_database (ctrl, "pubring.db", 0);

      kbxd_start_command_handler (ctrl, GNUPG_INVALID_FD, 0);
      kbxd_deinit_default_ctrl (ctrl);
      xfree (ctrl);
    }
  else if (!is_daemon)
    ; /* NOTREACHED */
  else
    { /* Regular daemon mode.  */
      gnupg_fd_t fd;
#ifndef HAVE_W32_SYSTEM
      pid_t pid;
#endif

      /* Create the sockets.  */
      socket_name = create_socket_name (KEYBOXD_SOCK_NAME, 1);
      fd = create_server_socket (socket_name, 0, &socket_nonce);

      fflush (NULL);

#ifdef HAVE_W32_SYSTEM

      (void)nodetach;
      initialize_modules ();

#else /*!HAVE_W32_SYSTEM*/

      pid = fork ();
      if (pid == (pid_t)-1)
        {
          log_fatal ("fork failed: %s\n", strerror (errno) );
          exit (1);
        }
      else if (pid)
        { /* We are the parent */

          /* Close the socket FD. */
          close (fd);

          /* The signal mask might not be correct right now and thus
           * we restore it.  That is not strictly necessary but some
           * programs falsely assume a cleared signal mask.  */

#ifdef HAVE_SIGPROCMASK
          if (startup_signal_mask_valid)
            {
              if (sigprocmask (SIG_SETMASK, &startup_signal_mask, NULL))
                log_error ("error restoring signal mask: %s\n",
                           strerror (errno));
            }
          else
            log_info ("no saved signal mask\n");
#endif /*HAVE_SIGPROCMASK*/

          *socket_name = 0; /* Don't let cleanup() remove the socket -
                               the child should do this from now on */

          exit (0);
          /*NOTREACHED*/
        } /* End parent */

      /*
       * This is the child
       */

      initialize_modules ();

      /* Detach from tty and put process into a new session */
      if (!nodetach)
        {
          int i;
          unsigned int oldflags;

          /* Close stdin, stdout and stderr unless it is the log stream */
          for (i=0; i <= 2; i++)
            {
              if (!log_test_fd (i) && i != fd )
                {
                  if ( ! close (i)
                       && open ("/dev/null", i? O_WRONLY : O_RDONLY) == -1)
                    {
                      log_error ("failed to open '%s': %s\n",
                                 "/dev/null", strerror (errno));
                      cleanup ();
                      exit (1);
                    }
                }
            }
          if (setsid() == -1)
            {
              log_error ("setsid() failed: %s\n", strerror(errno) );
              cleanup ();
              exit (1);
            }

          log_get_prefix (&oldflags);
          log_set_prefix (NULL, oldflags | GPGRT_LOG_RUN_DETACHED);
          opt.running_detached = 1;
        }

      {
        struct sigaction sa;

        sa.sa_handler = SIG_IGN;
        sigemptyset (&sa.sa_mask);
        sa.sa_flags = 0;
        sigaction (SIGPIPE, &sa, NULL);
      }
#endif /*!HAVE_W32_SYSTEM*/

      if (gnupg_chdir (gnupg_daemon_rootdir ()))
        {
          log_error ("chdir to '%s' failed: %s\n",
                     gnupg_daemon_rootdir (), strerror (errno));
          exit (1);
        }

      {
        ctrl_t ctrl;

        ctrl = xtrycalloc (1, sizeof *ctrl);
        if (!ctrl)
          {
            log_error ("error allocating connection control data: %s\n",
                       strerror (errno) );
            kbxd_exit (1);
          }
        kbxd_init_default_ctrl (ctrl);
        /* kbxd_set_database (ctrl, "pubring.kbx", 0); */
        kbxd_set_database (ctrl, "pubring.db", 0);
        kbxd_deinit_default_ctrl (ctrl);
        xfree (ctrl);
      }

      log_info ("%s %s started\n", gpgrt_strusage(11), gpgrt_strusage(13));
      handle_connections (fd);
      assuan_sock_close (fd);
    }

  return 0;
}


/* Exit entry point.  This function should be called instead of a
   plain exit.  */
void
kbxd_exit (int rc)
{
  /* As usual we run our cleanup handler.  */
  cleanup ();

  /* at this time a bit annoying */
  if ((opt.debug & DBG_MEMSTAT_VALUE))
    gcry_control (GCRYCTL_DUMP_MEMORY_STATS );
  rc = rc? rc : log_get_errorcount(0)? 2 : 0;
  exit (rc);
}


/* This is our callback function for gcrypt progress messages.  It is
 * set once at startup and dispatches progress messages to the
 * corresponding threads of ours.  */
static void
kbxd_libgcrypt_progress_cb (void *data, const char *what, int printchar,
                            int current, int total)
{
  struct progress_dispatch_s *dispatch;
  npth_t mytid = npth_self ();

  (void)data;

  for (dispatch = progress_dispatch_list; dispatch; dispatch = dispatch->next)
    if (dispatch->ctrl && dispatch->tid == mytid)
      break;
  if (dispatch && dispatch->cb)
    dispatch->cb (dispatch->ctrl, what, printchar, current, total);
}


/* If a progress dispatcher callback has been associated with the
 * current connection unregister it.  */
static void
unregister_progress_cb (void)
{
  struct progress_dispatch_s *dispatch;
  npth_t mytid = npth_self ();

  for (dispatch = progress_dispatch_list; dispatch; dispatch = dispatch->next)
    if (dispatch->ctrl && dispatch->tid == mytid)
      break;
  if (dispatch)
    {
      dispatch->ctrl = NULL;
      dispatch->cb = NULL;
    }
}


/* Setup a progress callback CB for the current connection.  Using a
 * CB of NULL disables the callback.  */
void
kbxd_set_progress_cb (void (*cb)(ctrl_t ctrl, const char *what,
                                 int printchar, int current, int total),
                      ctrl_t ctrl)
{
  struct progress_dispatch_s *dispatch, *firstfree;
  npth_t mytid = npth_self ();

  firstfree = NULL;
  for (dispatch = progress_dispatch_list; dispatch; dispatch = dispatch->next)
    {
      if (dispatch->ctrl && dispatch->tid == mytid)
        break;
      if (!dispatch->ctrl && !firstfree)
        firstfree = dispatch;
    }
  if (!dispatch) /* None allocated: Reuse or allocate a new one.  */
    {
      if (firstfree)
        {
          dispatch = firstfree;
        }
      else if ((dispatch = xtrycalloc (1, sizeof *dispatch)))
        {
          dispatch->next = progress_dispatch_list;
          progress_dispatch_list = dispatch;
        }
      else
        {
          log_error ("error allocating new progress dispatcher slot: %s\n",
                     gpg_strerror (gpg_error_from_syserror ()));
          return;
        }
      dispatch->ctrl = ctrl;
      dispatch->tid = mytid;
    }

  dispatch->cb = cb;
}


/* Each thread has its own local variables conveyed by a control
 * structure usually identified by an argument named CTRL.  This
 * function is called immediately after allocating the control
 * structure.  Its purpose is to setup the default values for that
 * structure.  Note that some values may have already been set.  */
static void
kbxd_init_default_ctrl (ctrl_t ctrl)
{
  ctrl->magic = SERVER_CONTROL_MAGIC;
}


/* Release all resources allocated by default in the control
   structure.  This is the counterpart to kbxd_init_default_ctrl.  */
static void
kbxd_deinit_default_ctrl (ctrl_t ctrl)
{
  if (!ctrl)
    return;
  kbxd_release_session_info (ctrl);
  ctrl->magic = 0xdeadbeef;
  unregister_progress_cb ();
  xfree (ctrl->lc_messages);
}


/* Reread parts of the configuration.  Note, that this function is
 * obviously not thread-safe and should only be called from the PTH
 * signal handler.
 *
 * Fixme: Due to the way the argument parsing works, we create a
 * memory leak here for all string type arguments.  There is currently
 * no clean way to tell whether the memory for the argument has been
 * allocated or points into the process's original arguments.  Unless
 * we have a mechanism to tell this, we need to live on with this. */
static void
reread_configuration (void)
{
  gpgrt_argparse_t pargs;
  char *twopart;
  int dummy;
  int logfile_seen = 0;

  if (!config_filename)
    goto finish; /* No config file. */

  twopart = strconcat ("keyboxd" EXTSEP_S "conf" PATHSEP_S,
                       config_filename, NULL);
  if (!twopart)
    return;  /* Out of core.  */

  parse_rereadable_options (NULL, 1); /* Start from the default values. */

  memset (&pargs, 0, sizeof pargs);
  dummy = 0;
  pargs.argc = &dummy;
  pargs.flags = (ARGPARSE_FLAG_KEEP
                 |ARGPARSE_FLAG_SYS
                 |ARGPARSE_FLAG_USER);
  while (gpgrt_argparser (&pargs, opts, twopart))
    {
      if (pargs.r_opt == ARGPARSE_CONFFILE)
        {
          log_info (_("reading options from '%s'\n"),
                    pargs.r_type? pargs.r.ret_str: "[cmdline]");
        }
      else if (pargs.r_opt < -1)
        pargs.err = ARGPARSE_PRINT_WARNING;
      else /* Try to parse this option - ignore unchangeable ones. */
        {
          if (pargs.r_opt == oLogFile)
            logfile_seen = 1;
          parse_rereadable_options (&pargs, 1);
        }
    }
  gpgrt_argparse (NULL, &pargs, NULL);  /* Release internal state.  */
  xfree (twopart);
  finalize_rereadable_options ();
  set_debug ();

 finish:
  /* Get a default log file from common.conf.  */
  if (!logfile_seen && !parse_comopt (GNUPG_MODULE_NAME_KEYBOXD, !!opt.debug))
    {
      if (!current_logfile || !comopt.logfile
          || strcmp (current_logfile, comopt.logfile))
        {
          log_set_file (comopt.logfile);
          xfree (current_logfile);
          current_logfile = comopt.logfile? xtrystrdup (comopt.logfile) : NULL;
        }
    }
}


/* Return the file name of the socket we are using for requests.  */
const char *
get_kbxd_socket_name (void)
{
  const char *s = socket_name;

  return (s && *s)? s : NULL;
}


/* Return the number of active connections. */
int
get_kbxd_active_connection_count (void)
{
  return active_connections;
}


/* Under W32, this function returns the handle of the scdaemon
   notification event.  Calling it the first time creates that
   event.  */
#if defined(HAVE_W32_SYSTEM)
static void *
create_an_event (void)
{
  HANDLE h, h2;
  SECURITY_ATTRIBUTES sa = { sizeof (SECURITY_ATTRIBUTES), NULL, TRUE};

  /* We need to use a manual reset event object due to the way our
     w32-pth wait function works: If we would use an automatic
     reset event we are not able to figure out which handle has
     been signaled because at the time we single out the signaled
     handles using WFSO the event has already been reset due to
     the WFMO.  */
  h = CreateEvent (&sa, TRUE, FALSE, NULL);
  if (!h)
    log_error ("can't create an event: %s\n", w32_strerror (-1) );
  else if (!DuplicateHandle (GetCurrentProcess(), h,
                             GetCurrentProcess(), &h2,
                             EVENT_MODIFY_STATE|SYNCHRONIZE, TRUE, 0))
    {
      log_error ("setting synchronize for an event failed: %s\n",
                 w32_strerror (-1) );
      CloseHandle (h);
    }
  else
    {
      CloseHandle (h);
      return h2;
    }

  return INVALID_HANDLE_VALUE;
}
#endif /*HAVE_W32_SYSTEM*/


/* Create a name for the socket in the home directory as using
 * STANDARD_NAME.  We also check for valid characters as well as
 * against a maximum allowed length for a Unix domain socket is done.
 * The function terminates the process in case of an error.  The
 * function returns a pointer to an allocated string with the absolute
 * name of the socket used.  */
static char *
create_socket_name (char *standard_name, int with_homedir)
{
  char *name;

  if (with_homedir)
    name = make_filename (gnupg_socketdir (), standard_name, NULL);
  else
    name = make_filename (standard_name, NULL);
  if (strchr (name, PATHSEP_C))
    {
      log_error (("'%s' are not allowed in the socket name\n"), PATHSEP_S);
      kbxd_exit (2);
    }
  return name;
}



/* Create a Unix domain socket with NAME.  Returns the file descriptor
 * or terminates the process in case of an error.  If CYGWIN is set a
 * Cygwin compatible socket is created (Windows only). */
static gnupg_fd_t
create_server_socket (char *name, int cygwin, assuan_sock_nonce_t *nonce)
{
  struct sockaddr *addr;
  struct sockaddr_un *unaddr;
  socklen_t len;
  gnupg_fd_t fd;
  int rc;

  fd = assuan_sock_new (AF_UNIX, SOCK_STREAM, 0);
  if (fd == ASSUAN_INVALID_FD)
    {
      log_error (_("can't create socket: %s\n"), strerror (errno));
      *name = 0; /* Inhibit removal of the socket by cleanup(). */
      kbxd_exit (2);
    }

  if (cygwin)
    assuan_sock_set_flag (fd, "cygwin", 1);

  unaddr = xmalloc (sizeof *unaddr);
  addr = (struct sockaddr*)unaddr;

  if (assuan_sock_set_sockaddr_un (name, addr, NULL))
    {
      if (errno == ENAMETOOLONG)
        log_error (_("socket name '%s' is too long\n"), name);
      else
        log_error ("error preparing socket '%s': %s\n",
                   name, gpg_strerror (gpg_error_from_syserror ()));
      *name = 0; /* Inhibit removal of the socket by cleanup(). */
      xfree (unaddr);
      kbxd_exit (2);
    }

  len = SUN_LEN (unaddr);
  rc = assuan_sock_bind (fd, addr, len);

  if (rc == -1
      && (errno == EADDRINUSE
#ifdef HAVE_W32_SYSTEM
          || errno == EEXIST
#endif
          ))
    {
      /* Check whether a keyboxd is already running.  */
      if (!check_for_running_kbxd (1))
        {
          if (steal_socket)
            log_info (N_("trying to steal socket from running %s\n"),
                      "keyboxd");
          else
            {
              log_set_prefix (NULL, GPGRT_LOG_WITH_PREFIX);
              log_set_file (NULL);
              log_error (_("a keyboxd is already running - "
                           "not starting a new one\n"));
              *name = 0; /* Inhibit removal of the socket by cleanup(). */
              assuan_sock_close (fd);
              xfree (unaddr);
              kbxd_exit (2);
            }
        }
      gnupg_remove (unaddr->sun_path);
      rc = assuan_sock_bind (fd, addr, len);
    }
  if (rc != -1 && (rc=assuan_sock_get_nonce (addr, len, nonce)))
    log_error (_("error getting nonce for the socket\n"));
  if (rc == -1)
    {
      /* We use gpg_strerror here because it allows us to get strings
         for some W32 socket error codes.  */
      log_error (_("error binding socket to '%s': %s\n"),
                 unaddr->sun_path, gpg_strerror (gpg_error_from_syserror ()));

      assuan_sock_close (fd);
      *name = 0; /* Inhibit removal of the socket by cleanup(). */
      xfree (unaddr);
      kbxd_exit (2);
    }

  if (gnupg_chmod (unaddr->sun_path, "-rwx"))
    log_error (_("can't set permissions of '%s': %s\n"),
               unaddr->sun_path, strerror (errno));

  if (listen (FD2INT(fd), listen_backlog ) == -1)
    {
      log_error ("listen(fd,%d) failed: %s\n", listen_backlog, strerror (errno));
      *name = 0; /* Inhibit removal of the socket by cleanup(). */
      assuan_sock_close (fd);
      xfree (unaddr);
      kbxd_exit (2);
    }

  if (opt.verbose)
    log_info (_("listening on socket '%s'\n"), unaddr->sun_path);

  xfree (unaddr);
  return fd;
}


/* Check that the directory for storing the public keys exists and
 * create it if not.  This function won't fail as it is only a
 * convenience function and not strictly necessary.  */
static void
create_public_keys_directory (const char *home)
{
  char *fname;
  struct stat statbuf;

  fname = make_filename (home, GNUPG_PUBLIC_KEYS_DIR, NULL);
  if (gnupg_stat (fname, &statbuf) && errno == ENOENT)
    {
      if (gnupg_mkdir (fname, "-rwxr-x"))
        log_error (_("can't create directory '%s': %s\n"),
                   fname, strerror (errno) );
      else if (!opt.quiet)
        log_info (_("directory '%s' created\n"), fname);
    }
  if (gnupg_chmod (fname, "-rwxr-x"))
    log_error (_("can't set permissions of '%s': %s\n"),
               fname, strerror (errno));
  xfree (fname);
}


/* Create the directory only if the supplied directory name is the
 * same as the default one.  This way we avoid to create arbitrary
 * directories when a non-default home directory is used.  To cope
 * with HOME, we compare only the suffix if we see that the default
 * homedir does start with a tilde.  We don't stop here in case of
 * problems because other functions will throw an error anyway.*/
static void
create_directories (void)
{
  struct stat statbuf;
  const char *defhome = standard_homedir ();
  char *home;

  home = make_filename (gnupg_homedir (), NULL);
  if (gnupg_stat (home, &statbuf))
    {
      if (errno == ENOENT)
        {
          if (
#ifdef HAVE_W32_SYSTEM
              ( !compare_filenames (home, defhome) )
#else
              (*defhome == '~'
                && (strlen (home) >= strlen (defhome+1)
                    && !strcmp (home + strlen(home)
                                - strlen (defhome+1), defhome+1)))
               || (*defhome != '~' && !strcmp (home, defhome) )
#endif
               )
            {
              if (gnupg_mkdir (home, "-rwx"))
                log_error (_("can't create directory '%s': %s\n"),
                           home, strerror (errno) );
              else
                {
                  if (!opt.quiet)
                    log_info (_("directory '%s' created\n"), home);
                  create_public_keys_directory (home);
                }
            }
        }
      else
        log_error (_("stat() failed for '%s': %s\n"), home, strerror (errno));
    }
  else if ( !S_ISDIR(statbuf.st_mode))
    {
      log_error (_("can't use '%s' as home directory\n"), home);
    }
  else /* exists and is a directory. */
    {
      create_public_keys_directory (home);
    }
  xfree (home);
}



/* A global function which allows us to call the reload stuff from
 * other places too.  This is only used when build for W32.  */
void
kbxd_sighup_action (void)
{
  log_info ("SIGHUP received - "
            "re-reading configuration and flushing cache\n");

  reread_configuration ();
}


/* A helper function to handle SIGUSR2.  */
static void
kbxd_sigusr2_action (void)
{
  if (opt.verbose)
    log_info ("SIGUSR2 received - no action\n");
  /* Nothing to do right now.  */
}


#ifndef HAVE_W32_SYSTEM
/* The signal handler for this program.  It is expected to be run in
 * its own thread and not in the context of a signal handler.  */
static void
handle_signal (int signo)
{
  switch (signo)
    {
    case SIGHUP:
      kbxd_sighup_action ();
      break;

    case SIGUSR1:
      log_info ("SIGUSR1 received - printing internal information:\n");
      /* Fixme: We need to see how to integrate pth dumping into our
         logging system.  */
      /* pth_ctrl (PTH_CTRL_DUMPSTATE, log_get_stream ()); */
      break;

    case SIGUSR2:
      kbxd_sigusr2_action ();
      break;

    case SIGCONT:
      /* Do nothing, but break the syscall.  */
      log_debug ("SIGCONT received - breaking select\n");
      break;

    case SIGTERM:
      if (!shutdown_pending)
        log_info ("SIGTERM received - shutting down ...\n");
      else
        log_info ("SIGTERM received - still %i open connections\n",
		  active_connections);
      shutdown_pending++;
      if (shutdown_pending > 2)
        {
          log_info ("shutdown forced\n");
          log_info ("%s %s stopped\n", gpgrt_strusage(11), gpgrt_strusage(13) );
          cleanup ();
          kbxd_exit (0);
	}
      break;

    case SIGINT:
      log_info ("SIGINT received - immediate shutdown\n");
      log_info( "%s %s stopped\n", gpgrt_strusage(11), gpgrt_strusage(13));
      cleanup ();
      kbxd_exit (0);
      break;

    default:
      log_info ("signal %d received - no action defined\n", signo);
    }
}
#endif

/* Check the nonce on a new connection.  This is a NOP unless we
   are using our Unix domain socket emulation under Windows.  */
static int
check_nonce (ctrl_t ctrl, assuan_sock_nonce_t *nonce)
{
  if (assuan_sock_check_nonce (ctrl->thread_startup.fd, nonce))
    {
      log_info (_("error reading nonce on fd %d: %s\n"),
                FD_DBG (ctrl->thread_startup.fd), strerror (errno));
      assuan_sock_close (ctrl->thread_startup.fd);
      xfree (ctrl);
      return -1;
    }
  else
    return 0;
}


static void *
do_start_connection_thread (ctrl_t ctrl)
{
  static unsigned int last_session_id;
  unsigned int session_id;

  active_connections++;
  kbxd_init_default_ctrl (ctrl);
  if (opt.verbose && !DBG_IPC)
    log_info (_("handler 0x%lx for fd %d started\n"),
              (unsigned long) npth_self(), FD_DBG (ctrl->thread_startup.fd));

  session_id = ++last_session_id;
  if (!session_id)
    session_id = ++last_session_id;
  kbxd_start_command_handler (ctrl, ctrl->thread_startup.fd, session_id);
  if (opt.verbose && !DBG_IPC)
    log_info (_("handler 0x%lx for fd %d terminated\n"),
              (unsigned long) npth_self(), FD_DBG (ctrl->thread_startup.fd));

  kbxd_deinit_default_ctrl (ctrl);
  xfree (ctrl);
  active_connections--;
  return NULL;
}


/* This is the standard connection thread's main function.  */
static void *
start_connection_thread (void *arg)
{
  ctrl_t ctrl = arg;

  if (check_nonce (ctrl, &socket_nonce))
    {
      log_error ("handler 0x%lx nonce check FAILED\n",
                 (unsigned long) npth_self());
      return NULL;
    }

  return do_start_connection_thread (ctrl);
}


static void
keyboxd_kick_the_loop (void)
{
  /* Kick the select loop.  */
#ifdef HAVE_W32_SYSTEM
  int ret = SetEvent (the_event2);
  if (ret == 0)
    log_error ("SetEvent for agent_kick_the_loop failed: %s\n",
               w32_strerror (-1));
#else
# ifdef HAVE_PSELECT_NO_EINTR
  write (event_pipe_fd, "", 1);
# else
  int ret = kill (main_thread_pid, SIGCONT);
  if (ret < 0)
    log_error ("sending signal for agent_kick_the_loop failed: %s\n",
               gpg_strerror (gpg_error_from_syserror ()));
# endif
#endif
}


/* Connection handler loop.  Wait for connection requests and spawn a
 * thread after accepting a connection.  */
static void
handle_connections (gnupg_fd_t listen_fd)
{
  gpg_error_t err;
  npth_attr_t tattr;
  struct sockaddr_un paddr;
  socklen_t plen;
  fd_set fdset, read_fdset;
  int ret;
  gnupg_fd_t fd;
  int nfd;
  int saved_errno;
#ifdef HAVE_W32_SYSTEM
  HANDLE events[2];
  unsigned int events_set;
#else
  int signo;
# ifdef HAVE_PSELECT_NO_EINTR
  int pipe_fd[2];
# endif
#endif
  int sock_inotify_fd = -1;
  int home_inotify_fd = -1;
  struct {
    const char *name;
    void *(*func) (void *arg);
    gnupg_fd_t l_fd;
  } listentbl[] = {
    { "std",     start_connection_thread },
  };
  int have_homedir_inotify = 0;

  ret = npth_attr_init(&tattr);
  if (ret)
    log_fatal ("error allocating thread attributes: %s\n", strerror (ret));
  npth_attr_setdetachstate (&tattr, NPTH_CREATE_DETACHED);

#ifndef HAVE_W32_SYSTEM
  npth_sigev_init ();
  npth_sigev_add (SIGHUP);
  npth_sigev_add (SIGUSR1);
  npth_sigev_add (SIGUSR2);
  npth_sigev_add (SIGINT);
  npth_sigev_add (SIGCONT);
  npth_sigev_add (SIGTERM);
  npth_sigev_fini ();
# ifdef HAVE_PSELECT_NO_EINTR
  ret = gnupg_create_pipe (pipe_fd, 0);
  if (ret)
    {
      log_error ("pipe creation failed: %s\n", gpg_strerror (ret));
      return;
    }
  event_pipe_fd = pipe_fd[1];
# else
  main_thread_pid = getpid ();
# endif
#else
  events[0] = the_event2 = create_an_event ();
  events[1] = INVALID_HANDLE_VALUE;
#endif

  if (disable_check_own_socket)
    sock_inotify_fd = -1;
  else if ((err = gnupg_inotify_watch_socket (&sock_inotify_fd, socket_name)))
    {
      if (gpg_err_code (err) != GPG_ERR_NOT_SUPPORTED)
        log_info ("error enabling daemon termination by socket removal: %s\n",
                  gpg_strerror (err));
    }

  if ((err = gnupg_inotify_watch_delete_self (&home_inotify_fd,
                                              gnupg_homedir ())))
    {
      if (gpg_err_code (err) != GPG_ERR_NOT_SUPPORTED)
        log_info ("error enabling daemon termination by homedir removal: %s\n",
                  gpg_strerror (err));
    }
  else
    have_homedir_inotify = 1;

#if CHECK_OWN_SOCKET_INTERVAL > 0
  if (!disable_check_own_socket && sock_inotify_fd == -1)
    {
      npth_t thread;

      err = npth_create (&thread, &tattr, check_own_socket_thread, NULL);
      if (err)
        log_error ("error spawning check_own_socket_thread: %s\n", strerror (err));
    }
#endif

  if (!have_homedir_inotify)
    {
      npth_t thread;

      err = npth_create (&thread, &tattr, check_others_thread, NULL);
      if (err)
        log_error ("error spawning check_others_thread: %s\n", strerror (err));
    }

  FD_ZERO (&fdset);
  FD_SET (FD2INT (listen_fd), &fdset);
  nfd = FD2NUM (listen_fd);
  if (sock_inotify_fd != -1)
    {
      FD_SET (sock_inotify_fd, &fdset);
      if (sock_inotify_fd > nfd)
        nfd = sock_inotify_fd;
    }
  if (home_inotify_fd != -1)
    {
      FD_SET (home_inotify_fd, &fdset);
      if (home_inotify_fd > nfd)
        nfd = home_inotify_fd;
    }

  listentbl[0].l_fd = listen_fd;

  for (;;)
    {
      /* Shutdown test.  */
      if (shutdown_pending)
        {
          if (!active_connections)
            break; /* ready */

          /* Do not accept new connections but keep on running the
           * loop to cope with the timer events.
           *
           * Note that we do not close the listening socket because a
           * client trying to connect to that socket would instead
           * restart a new keyboxd instance - which is unlikely the
           * intention of a shutdown. */
          FD_ZERO (&fdset);
          nfd = -1;
          if (sock_inotify_fd != -1)
            {
              FD_SET (sock_inotify_fd, &fdset);
              nfd = sock_inotify_fd;
            }
          if (home_inotify_fd != -1)
            {
              FD_SET (home_inotify_fd, &fdset);
              if (home_inotify_fd > nfd)
                nfd = home_inotify_fd;
            }
	}

      read_fdset = fdset;

#ifdef HAVE_PSELECT_NO_EINTR
      FD_SET (pipe_fd[0], &read_fdset);
      if (nfd < pipe_fd[0])
        nfd = pipe_fd[0];
#endif

#ifndef HAVE_W32_SYSTEM
      ret = npth_pselect (nfd+1, &read_fdset, NULL, NULL, NULL,
                          npth_sigev_sigmask ());
      saved_errno = errno;

      while (npth_sigev_get_pending (&signo))
        handle_signal (signo);
#else
      ret = npth_eselect (nfd+1, &read_fdset, NULL, NULL, NULL,
                          events, &events_set);
      saved_errno = errno;

      /* This is valid even if npth_eselect returns an error.  */
      if ((events_set & 1))
	kbxd_sigusr2_action ();
#endif

      if (ret == -1 && saved_errno != EINTR)
	{
          log_error (_("npth_pselect failed: %s - waiting 1s\n"),
                     strerror (saved_errno));
          gnupg_sleep (1);
          continue;
	}

      if ((problem_detected & KEYBOXD_PROBLEM_SOCKET_TAKEOVER))
        {
          /* We may not remove the socket as it is now in use by another
             server. */
          inhibit_socket_removal = 1;
          shutdown_pending = 2;
          log_info ("this process is useless - shutting down\n");
        }

      if ((problem_detected & KEYBOXD_PROBLEM_HOMEDIR_REMOVED))
        {
          shutdown_pending = 1;
          log_info ("homedir has been removed - shutting down\n");
        }

      if (ret <= 0)
        {
          /* Interrupt or timeout.  Will be handled when calculating the
           * next timeout.  */
          continue;
        }

#ifdef HAVE_PSELECT_NO_EINTR
      if (FD_ISSET (pipe_fd[0], &read_fdset))
        {
          char buf[256];

          read (pipe_fd[0], buf, sizeof buf);
        }
#endif

      /* The inotify fds are set even when a shutdown is pending (see
       * above).  So we must handle them in any case.  To avoid that
       * they trigger a second time we close them immediately.  */
      if (sock_inotify_fd != -1
          && FD_ISSET (sock_inotify_fd, &read_fdset)
          && gnupg_inotify_has_name (sock_inotify_fd, KEYBOXD_SOCK_NAME))
        {
          shutdown_pending = 1;
          close (sock_inotify_fd);
          sock_inotify_fd = -1;
          log_info ("socket file has been removed - shutting down\n");
        }

      if (home_inotify_fd != -1
          && FD_ISSET (home_inotify_fd, &read_fdset))
        {
          shutdown_pending = 1;
          close (home_inotify_fd);
          home_inotify_fd = -1;
          log_info ("homedir has been removed - shutting down\n");
        }

      if (!shutdown_pending)
        {
          int idx;
          ctrl_t ctrl;
          npth_t thread;

          for (idx=0; idx < DIM(listentbl); idx++)
            {
              if (listentbl[idx].l_fd == GNUPG_INVALID_FD)
                continue;
              if (!FD_ISSET (FD2INT (listentbl[idx].l_fd), &read_fdset))
                continue;

              plen = sizeof paddr;
              fd = assuan_sock_accept (listentbl[idx].l_fd,
                                       (struct sockaddr *)&paddr, &plen);
              if (fd == GNUPG_INVALID_FD)
                {
                  log_error ("accept failed for %s: %s\n",
                             listentbl[idx].name, strerror (errno));
                }
              else if ( !(ctrl = xtrycalloc (1, sizeof *ctrl)))
                {
                  log_error ("error allocating connection data for %s: %s\n",
                             listentbl[idx].name, strerror (errno) );
                  assuan_sock_close (fd);
                }
              else
                {
                  ctrl->thread_startup.fd = fd;
                  ret = npth_create (&thread, &tattr,
                                     listentbl[idx].func, ctrl);
                  if (ret)
                    {
                      log_error ("error spawning connection handler for %s:"
                                 " %s\n", listentbl[idx].name, strerror (ret));
                      assuan_sock_close (fd);
                      xfree (ctrl);
                    }
                }
            }
        }
    }

  if (sock_inotify_fd != -1)
    close (sock_inotify_fd);
  if (home_inotify_fd != -1)
    close (home_inotify_fd);
#ifdef HAVE_W32_SYSTEM
  if (the_event2 != INVALID_HANDLE_VALUE)
    CloseHandle (the_event2);
#endif
#ifdef HAVE_PSELECT_NO_EINTR
  close (pipe_fd[0]);
  close (pipe_fd[1]);
#endif
  cleanup ();
  log_info (_("%s %s stopped\n"), gpgrt_strusage(11), gpgrt_strusage(13));
  npth_attr_destroy (&tattr);
}


#if CHECK_OWN_SOCKET_INTERVAL > 0
/* Helper for check_own_socket.  */
static gpg_error_t
check_own_socket_pid_cb (void *opaque, const void *buffer, size_t length)
{
  membuf_t *mb = opaque;
  put_membuf (mb, buffer, length);
  return 0;
}


/* Check whether we are still listening on our own socket.  In case
   another gpg-agent process started after us has taken ownership of
   our socket, we would linger around without any real task.  Thus we
   better check once in a while whether we are really needed.  */
static int
do_check_own_socket (const char *sockname)
{
  int rc;
  assuan_context_t ctx = NULL;
  membuf_t mb;
  char *buffer;

  rc = assuan_new (&ctx);
  if (rc)
    {
      log_error ("can't allocate assuan context: %s\n", gpg_strerror (rc));
      goto leave;
    }
  assuan_set_flag (ctx, ASSUAN_NO_LOGGING, 1);

  rc = assuan_socket_connect (ctx, sockname, (pid_t)(-1), 0);
  if (rc)
    {
      log_error ("can't connect my own socket: %s\n", gpg_strerror (rc));
      goto leave;
    }

  init_membuf (&mb, 100);
  rc = assuan_transact (ctx, "GETINFO pid", check_own_socket_pid_cb, &mb,
                        NULL, NULL, NULL, NULL);
  put_membuf (&mb, "", 1);
  buffer = get_membuf (&mb, NULL);
  if (rc || !buffer)
    {
      log_error ("sending command \"%s\" to my own socket failed: %s\n",
                 "GETINFO pid", gpg_strerror (rc));
      rc = 1;
    }
  else if ( (pid_t)strtoul (buffer, NULL, 10) != getpid ())
    {
      log_error ("socket is now serviced by another server\n");
      rc = 1;
    }
  else if (opt.verbose > 1)
    log_error ("socket is still served by this server\n");

  xfree (buffer);

 leave:
  if (ctx)
    assuan_release (ctx);

  return rc;
}

/* The thread running the actual check.  */
static void *
check_own_socket_thread (void *arg)
{
  char *sockname;

  (void)arg;

  sockname = make_filename_try (gnupg_socketdir (), KEYBOXD_SOCK_NAME, NULL);
  if (!sockname)
    return NULL; /* Out of memory.  */

  while (!problem_detected)
    {
      if (shutdown_pending)
        goto leave;

      gnupg_sleep (CHECK_OWN_SOCKET_INTERVAL);

      if (do_check_own_socket (sockname))
        problem_detected |= KEYBOXD_PROBLEM_SOCKET_TAKEOVER;
    }

  keyboxd_kick_the_loop ();

 leave:
  xfree (sockname);
  return NULL;
}
#endif

/* The thread running other checks.  */
static void *
check_others_thread (void *arg)
{
  const char *homedir = gnupg_homedir ();

  (void)arg;

  while (!problem_detected)
    {
      struct stat statbuf;

      if (shutdown_pending)
        goto leave;

      gnupg_sleep (CHECK_PROBLEMS_INTERVAL);

      /* Check whether the homedir is still available.  */
      if (gnupg_stat (homedir, &statbuf) && errno == ENOENT)
        problem_detected |= KEYBOXD_PROBLEM_HOMEDIR_REMOVED;
    }

  keyboxd_kick_the_loop ();

 leave:
  return NULL;
}


/* Figure out whether a keyboxd is available and running.  Prints an
 * error if not.  If SILENT is true, no messages are printed.  Returns
 * 0 if the agent is running. */
static int
check_for_running_kbxd (int silent)
{
  gpg_error_t err;
  char *sockname;
  assuan_context_t ctx = NULL;

  sockname = make_filename_try (gnupg_socketdir (), KEYBOXD_SOCK_NAME, NULL);
  if (!sockname)
    return gpg_error_from_syserror ();

  err = assuan_new (&ctx);
  if (!err)
    err = assuan_socket_connect (ctx, sockname, (pid_t)(-1), 0);
  xfree (sockname);
  if (err)
    {
      if (!silent)
        log_error (_("no keyboxd running in this session\n"));

      if (ctx)
	assuan_release (ctx);
      return -1;
    }

  if (!opt.quiet && !silent)
    log_info ("keyboxd running and available\n");

  assuan_release (ctx);
  return 0;
}