/* $Id: vidb.C,v 1.1 2001/08/20 04:43:24 dm Exp $ */

/*
 *
 * Copyright (C) 2001 David Mazieres (dm@uun.org)
 *
 * 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, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 */

#include "authdb.h"
#include "sfsmisc.h"
#include "init.h"

str db;
mode_t dbmode;
str editor;
ptr<lockfile> dblock;
str dottmp;
str tmppath;

EXITFN (cleanup);
static void
cleanup ()
{
  if (tmppath)
    unlink (tmppath);
}

static void
lockit (str file, bool wait)
{
  dblock = lockfile::alloc (file << ".lock");
  if (!dblock) {
    if (!wait)
      fatal << file << ": could not lock file\n";
    warn << ": waiting for lock on " << file << "...";
    dblock = lockfile::alloc (file << ".lock", true);
    warnx << "\n";
  }
  // In case we die but not editor, best NOT to close on exec
  fcntl (dblock->fd, F_SETFD, 0);
  dottmp = file << ".tmp";
}

static void
copyit (str file)
{
  int rfd = open (file, O_RDONLY);
  struct stat sb;
  if (rfd < 0 || fstat (rfd, &sb) < 0)
    fatal << file << ": " << strerror (errno) << "\n";
  dbmode = sb.st_mode;

  int wfd = open (dottmp, O_WRONLY|O_CREAT|O_TRUNC|O_EXCL,
		  0600 | dbmode & 0777);
  if (wfd < 0) {
    if (errno == EEXIST)
      fatal << dottmp << " exists, please remove file or use -r flag\n";
    fatal << dottmp << ": " << strerror (errno) << "\n";
  }
  tmppath = dottmp;

  char buf[8192];
  int n;
  while ((n = read (rfd, buf, sizeof (buf))) > 0)
    if (write (wfd, buf, n) != n)
      fatal << tmppath << ": " << strerror (errno) << "\n";
  if (n < 0)
    fatal << file << ": " << strerror (errno) << "\n";
  close (rfd);
  close (wfd);
}

static void
finish (int status)
{
  if (status)
    fatal << editor << ": abnormal exit\n";
  int wfd = open (tmppath, O_WRONLY);
  if (wfd < 0 || fsync (wfd) < 0 || close (wfd) < 0
      || chmod (tmppath, dbmode) < 0)
    fatal << tmppath << ": " << strerror (errno) << "\n";
  if (!dblock->ok ()) {
    str target = db << ".bak";
    if (rename (dottmp, target) < 0)
      fatal << dottmp << ": " << strerror (errno) << "\n";
    dblock = NULL;
    tmppath = NULL;
    fatal << "lock was stolen -- file saved in " << target << "\n";
  }
  if (rename (tmppath, db) < 0)
    fatal << db << ": " << strerror (errno) << "\n";
  exit (0);
}

static void
usage ()
{
  warnx << "usage: " << progname << " [-r] [-w] [-e editor] dbfile\n";
  exit (1);
}

int
main (int argc, char **argv)
{
  setprogname (argv[0]);

  editor = getenv ("EDITOR");
  bool opt_recover = false, opt_wait = false;
  int ch;
  while ((ch = getopt (argc, argv, "rwe:")) != -1)
    switch (ch) {
    case 'r':
      opt_recover = true;
      break;
    case 'w':
      opt_wait = true;
      break;
    case 'e':
      editor = optarg;
      break;
    default:
      usage ();
    }

  if (optind + 1 != argc)
    usage ();
  db = argv[optind];

  if (!editor)
    editor = "vi";
  if (str edpath = find_program (editor))
    editor = edpath;
  else
    fatal << editor << ": " << strerror (errno) << "\n";

  lockit (db, opt_wait);
  if (opt_recover) {
    str target = db << ".bak";
    if (rename (dottmp, target) == 0)
      warn << "saved old " << dottmp << " in " << target << "\n";
  }
  copyit (db);
  const char *av[] = { editor, tmppath, NULL };
  pid_t pid = spawn (editor, av);
  if (pid == -1)
    fatal << editor << ": " << strerror (errno) << "\n";

  int status = -1;
  waitpid (pid, &status, 0);
  finish (status);
  return 0;
}