/*----------------------------------------------------------------------*
 * File:	rxvtd.C
 *----------------------------------------------------------------------*
 *
 * All portions of code are copyright by their respective author/s.
 * Copyright (c) 2003-2007 Marc Lehmann <schmorp@schmorp.de>
 *
 * 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *----------------------------------------------------------------------*/

#include "../config.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>

#if defined(ENABLE_FRILLS) && defined(_POSIX_MEMLOCK) && _POSIX_MEMLOCK > 0
# define ENABLE_MLOCK 1
#endif

#if ENABLE_MLOCK
# include <sys/mman.h>
#endif

#include <errno.h>

#include <libptytty.h>

#include "rxvt.h"
#include "rxvtdaemon.h"

struct server : rxvt_connection
{
  log_callback log_cb;
  getfd_callback getfd_cb;

  void read_cb (ev::io &w, int revents); ev::io read_ev;
  void log_msg (const char *msg);
  int getfd (int remote_fd);

  server (int fd)
  {
    read_ev.set <server, &server::read_cb> (this);
    log_cb.set  <server, &server::log_msg> (this);
    getfd_cb.set<server, &server::getfd>   (this);

    this->fd = fd;
    fcntl (fd, F_SETFD, FD_CLOEXEC);
    fcntl (fd, F_SETFL, 0);
    read_ev.start (fd, ev::READ);
  }

  void err (const char *format = 0, ...);
};

struct unix_listener
{
  int fd;

  void accept_cb (ev::io &w, int revents); ev::io accept_ev;

  unix_listener (int fd);
  static int open (const char *sockname);
};

unix_listener::unix_listener (int fd) : fd (fd)
{
  accept_ev.set<unix_listener, &unix_listener::accept_cb> (this);
  fcntl (fd, F_SETFD, FD_CLOEXEC);
  fcntl (fd, F_SETFL, O_NONBLOCK);
  accept_ev.start (fd, ev::READ);
}

int unix_listener::open (const char *sockname)
{
  sockaddr_un sa;

  if (strlen (sockname) >= sizeof(sa.sun_path))
    {
      fputs ("socket name too long, aborting.\n", stderr);
      exit (EXIT_FAILURE);
    }

  int fd;
  if ((fd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
    {
      perror ("unable to create listening socket");
      exit (EXIT_FAILURE);
    }

  sa.sun_family = AF_UNIX;
  strcpy (sa.sun_path, sockname);

  unlink (sockname);

  mode_t omask = umask (0077);

  if (bind (fd, (sockaddr *)&sa, sizeof (sa)))
    {
      perror ("unable to bind listening socket");
      exit (EXIT_FAILURE);
    }

  umask (omask);

  if (listen (fd, 5))
    {
      perror ("unable to listen on socket");
      exit (EXIT_FAILURE);
    }

  return fd;
}

void unix_listener::accept_cb (ev::io &w, int revents)
{
  int fd2 = accept (fd, 0, 0);

  if (fd2 >= 0)
    new server (fd2);
}

int server::getfd (int remote_fd)
{
  send ("GETFD");
  send (remote_fd);
  return ptytty::recv_fd (fd);
}

void server::log_msg (const char *msg)
{
  send ("MSG"), send (msg);
}

void server::err (const char *format, ...)
{
  if (format)
    {
      char err[1024];

      va_list ap;
      va_start (ap, format);
      vsnprintf (err, 1024, format, ap);
      va_end (ap);

      log_msg (err);
    }

  send ("END"), send (0);
  close (fd);
  delete this;
}

void server::read_cb (ev::io &w, int revents)
{
  auto_str tok;

  if (recv (tok))
    {
      if (!strcmp (tok, "NEW"))
        {
          stringvec *argv = new stringvec;
          stringvec *envv = new stringvec;

          for (;;)
            {
              if (!recv (tok))
                return err ();

              if (!strcmp (tok, "END"))
                break;
              else if (!strcmp (tok, "ENV") && recv (tok))
                envv->push_back (strdup (tok));
              else if (!strcmp (tok, "ARG") && recv (tok))
                argv->push_back (strdup (tok));
              else
                return err ("protocol error: unexpected NEW token.\n");
            }

          {
            rxvt_term *term = new rxvt_term;

            term->log_hook = &log_cb;
            term->getfd_hook = &getfd_cb;

            bool success = true;

            try
              {
                term->init (argv, envv);
              }
            catch (const std::exception &e)
              {
                log_msg (e.what());
                success = false;
              }

            term->log_hook = 0;

            chdir ("/"); // init might change to different working directory

            if (!success)
              term->destroy ();

            send ("END"); send (success ? 1 : 0);
          }
        }
      else if (!strcmp (tok, "QUIT"))
        _exit (0);
      else
        return err ("protocol error: request '%s' unsupported.\n", (char *)tok);
    }
  else
    return err ();
}

#ifdef ENABLE_FRILLS
enum {
  SD_LISTEN_FDS_START = 3,
};

// https://www.freedesktop.org/software/systemd/man/sd_listen_fds.html
// https://github.com/systemd/systemd/blob/main/src/libsystemd/sd-daemon/sd-daemon.c
static int get_listen_fds ()
{
  const char *listen_pid = getenv ("LISTEN_PID");
  if (!listen_pid)
    return 0;

  char *end;
  errno = 0;
  long pid = strtol (listen_pid, &end, 10);
  if (errno || end == listen_pid || *end)
    return -1;

  if (getpid () != pid)
    return 0;

  const char *listen_fds = getenv ("LISTEN_FDS");
  if (!listen_fds)
    return 0;

  errno = 0;
  long n = strtol (listen_fds, &end, 10);
  if (errno || end == listen_fds || *end)
    return -1;

  if (n <= 0 || n > INT_MAX - SD_LISTEN_FDS_START)
    return -1;

  unsetenv ("LISTEN_PID");
  unsetenv ("LISTEN_FDS");
  unsetenv ("LISTEN_FDNAMES");

  return n;
}
#endif

int
main (int argc, char *argv[])
{
  try
    {
      ptytty::init ();
    }
  catch (const std::exception &e)
    {
      fputs (e.what (), stderr);
      return EXIT_FAILURE;
    }

  static char opt_fork, opt_opendisplay, opt_quiet;
#if ENABLE_PERL
  static char *opt_eval;
#endif
#if ENABLE_MLOCK
  static char opt_lock;
#endif

  for (int i = 1; i < argc; i++)
    {
      if (!strcmp (argv [i], "-f") || !strcmp (argv [i], "--fork"))
        opt_fork = 1;
      else if (!strcmp (argv [i], "-o") || !strcmp (argv [i], "--opendisplay"))
        opt_opendisplay = 1;
      else if (!strcmp (argv [i], "-q") || !strcmp (argv [i], "--quiet"))
        opt_quiet = 1;
#if ENABLE_MLOCK
      else if (!strcmp (argv [i], "-m") || !strcmp (argv [i], "--mlock"))
        opt_lock = 1;
#endif
#if ENABLE_PERL
      else if (!strcmp (argv [i], "-e") || !strcmp (argv [i], "--eval"))
        opt_eval = argv [++i];
#endif
      else
        {
          rxvt_log ("%s: unknown option '%s', aborting.\n", argv [0], argv [i]);
          return EXIT_FAILURE;
        }
    }

  rxvt_init ();

#if ENABLE_PERL
  if (opt_eval)
    {
      rxvt_perl.init ();
      rxvt_perl.eval (opt_eval);
    }
#endif

  // optionally open display and never release it.
  if (opt_opendisplay)
    if (const char *dpy = getenv ("DISPLAY"))
      displays.get (dpy ? dpy : ":0"); // move string logic into rxvt_display maybe?

  int fd;
#ifdef ENABLE_FRILLS
  int n = get_listen_fds ();
  if (n > 1)
    {
      fputs ("received multiple file descriptors, aborting.\n", stderr);
      exit (EXIT_FAILURE);
    }
  else if (n == 1)
    {
      fd = SD_LISTEN_FDS_START;
      if (!opt_quiet)
        {
          printf ("rxvt-unicode daemon listening on fd.\n");
          fflush (stdout);
        }
    }
  else
#endif
    {
      char *sockname = rxvt_connection::unix_sockname ();
      fd = unix_listener::open (sockname);
      if (!opt_quiet)
        {
          printf ("rxvt-unicode daemon listening on %s.\n", sockname);
          fflush (stdout);
        }
      free (sockname);
    }

  unix_listener l (fd);

  chdir ("/");

  pid_t pid = 0;
  if (opt_fork)
    {
      pid = fork ();
    }

#if ENABLE_MLOCK
  // Optionally perform an mlockall so this process does not get swapped out.
  if (opt_lock && !pid)
    if (mlockall (MCL_CURRENT | MCL_FUTURE) < 0)
      perror ("unable to lock into ram");
#endif

  if (opt_fork)
    {
      if (pid < 0)
        {
          rxvt_log ("unable to fork daemon, aborting.\n");
          return EXIT_FAILURE;
        }
      else if (pid > 0)
        _exit (EXIT_SUCCESS);

      ev_loop_fork (EV_DEFAULT_UC);
    }

  ev_run ();

  return EXIT_SUCCESS;
}