/*
 * FCRON - periodic command scheduler 
 *
 *  Copyright 2000-2014 Thibault Godouet <fcron@free.fr>
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 *  The GNU General Public License can also be found in the file
 *  `LICENSE' that comes with the fcron source distribution.
 */


#include "fcronsighup.h"
#include "global.h"
#include "allow.h"
#include "fcronconf.h"


void usage(void);
void sig_daemon(void);
pid_t read_pid(void);

uid_t uid = 0;
uid_t fcrontab_uid = 0;
uid_t rootuid = 0;
gid_t rootgid = 0;

/* needed by log part : */
char *prog_name = NULL;
char foreground = 1;
pid_t daemon_pid = 0;


void
usage(void)
  /*  print a help message about command line options and exit */
{
    fprintf(stderr,
            "fcronsighup " VERSION_QUOTED " - make fcron update its fcrontabs\n"
            "Copyright " COPYRIGHT_QUOTED " Thibault Godouet <fcron@free.fr>\n"
            "This program is free software distributed WITHOUT ANY WARRANTY.\n"
            "See the GNU General Public License for more details.\n" "\n");

    fprintf(stderr,
            "fcronsighup [fcronconf]\n"
            "  Signal fcron process using fcronconf configuration file\n"
            "  (or default configuration file " ETC "/" FCRON_CONF ").\n" "\n");

    exit(EXIT_ERR);

}

pid_t
read_pid(void)
    /* return fcron daemon's pid if running.
     * otherwise return 0 */
{
    FILE *fp = NULL;
    pid_t pid = 0;

    if ((fp = fopen(pidfile, "r")) != NULL) {
        if (fscanf(fp, "%" ATTR_SIZE_PIDT "d", CAST_PIDT_PTR & pid) < 1)
            error("Unable to read fcron daemon's pid (fscanf(fp,...))");
        xfclose_check(&fp, pidfile);
    }

    return pid;
}


void
sig_daemon(void)
    /* send SIGHUP to daemon to tell him configuration has changed */
    /* SIGHUP is sent once 10s before the next minute to avoid
     * some bad users to block daemon by sending it SIGHUP all the time */
{
    /* we don't need to make root wait */
    if (uid != rootuid) {
        time_t t = 0;
        int sl = 0;
        FILE *fp = NULL;
        int fd = 0;
        struct tm *tm = NULL;
        char sigfile[PATH_LEN];
        char buf[PATH_LEN];

        sigfile[0] = '\0';
        t = time(NULL);
        tm = localtime(&t);

        if ((sl = 60 - (t % 60) - 10) < 0) {
            if ((tm->tm_min = tm->tm_min + 2) >= 60) {
                tm->tm_hour++;
                tm->tm_min -= 60;
            }
            snprintf(buf, sizeof(buf), "%02d:%02d", tm->tm_hour, tm->tm_min);
            sl = 60 - (t % 60) + 50;
        }
        else {
            if (++tm->tm_min >= 60) {
                tm->tm_hour++;
                tm->tm_min -= 60;
            }
            snprintf(buf, sizeof(buf), "%02d:%02d", tm->tm_hour, tm->tm_min);
        }
        fprintf(stderr, "Modifications will be taken into account"
                " at %s.\n", buf);

        /* if fcrontabs is too long, snprintf will not be able to add "/fcrontab.sig"
         * string at the end of sigfile */
        if (strlen(fcrontabs) > (sizeof(sigfile) - sizeof("/fcrontab.sig")))
            die("fcrontabs string too long (more than %d characters)",
                (sizeof(sigfile) - sizeof("/fcrontab.sig")));
        snprintf(sigfile, sizeof(sigfile), "%s/fcrontab.sig", fcrontabs);

        switch (fork()) {
        case -1:
            remove(sigfile);
            die_e("could not fork : daemon has not been signaled");
            break;
        case 0:
            /* child */
            break;
        default:
            /* parent */
            return;
        }

        foreground = 0;

        /* try to create a lock file */
        /* // */
        debug("uid: %d, euid: %d, gid: %d, egid: %d", getuid(), geteuid(),
              getgid(), getegid());
        /* // */
        fd = open(sigfile, O_RDWR | O_CREAT, 0644);
        if (fd == -1)
            die_e("can't open or create %s", sigfile);
        fp = fdopen(fd, "r+");
        if (fp == NULL)
            die_e("can't fdopen %s", sigfile);


#ifdef HAVE_FLOCK
        if (flock(fd, LOCK_EX | LOCK_NB) != 0) {
            debug("fcrontab is already waiting for signalling the daemon :"
                  " exiting.");
            return;
        }
#else                           /* HAVE_FLOCK */
        if (lockf(fd, F_TLOCK, 0) != 0) {
            debug("fcrontab is already waiting for signalling the daemon :"
                  " exiting.");
            return;
        }
#endif                          /* ! HAVE_FLOCK */

        sleep(sl);

        /* also closes the underlying file descriptor fd: */
        xfclose_check(&fp, sigfile);
        /* also reset fd, now closed by xfclose_check(), to make it clear it is closed */
        fd = -1;

        if (remove(sigfile) < 0)
            error_e("Could not remove %s");
    }
    else
        /* we are root */
        fprintf(stderr,
                "Modifications will be taken into account" " right now.\n");

    if ((daemon_pid = read_pid()) == 0)
        /* daemon is not running any longer : we exit */
        return;

    foreground = 1;

#ifdef USE_SETE_ID
    if (seteuid(rootuid) != 0)
        error_e("seteuid(rootuid)");
#endif                          /* USE_SETE_ID */

    if (kill(daemon_pid, SIGHUP) != 0)
        die_e("could not send SIGHUP to daemon (pid %d)", daemon_pid);

#ifdef USE_SETE_ID
    /* get user's permissions */
    if (seteuid(fcrontab_uid) != 0)
        die_e("Could not change euid to " USERNAME "[%d]", uid);
#endif                          /* USE_SETE_ID */

}


int
main(int argc, char **argv)
{
    struct passwd *pass = NULL;
    char *cur_user = NULL;

    rootuid = get_user_uid_safe(ROOTNAME);
    rootgid = get_group_gid_safe(ROOTGROUP);

    if (strrchr(argv[0], '/') == NULL)
        prog_name = argv[0];
    else
        prog_name = strrchr(argv[0], '/') + 1;

    fcrontab_uid = get_user_uid_safe(USERNAME);

#ifdef USE_SETE_ID
    /* get user's permissions */
    if (seteuid(fcrontab_uid) != 0)
        die_e("Could not change euid to " USERNAME "[%d]", uid);
#endif                          /* USE_SETE_ID */

    if (argc == 2)
        fcronconf = argv[1];
    else if (argc > 2)
        usage();

    /* read fcron.conf and update global parameters */
    /* We deactivate output to console, because otherwise it may be used
     * by a malicious user to read some data it is not allow to read
     * (fcronsighup is suid root) */
    foreground = 0;
    read_conf();
    foreground = 1;

    uid = getuid();

    /* check if user is allowed to use this program */
    if (!(pass = getpwuid(uid)))
        die("user \"%s\" is not in passwd file. Aborting.", USERNAME);
    cur_user = strdup2(pass->pw_name);

    if (is_allowed(cur_user)) {
        /* check if daemon is running */
        if ((daemon_pid = read_pid()) != 0)
            sig_daemon();
        else
            fprintf(stderr, "fcron is not running :\n  modifications will"
                    " be taken into account at its next execution.\n");
    }
    else
        die("User \"%s\" is not allowed to use %s. Aborting.", cur_user,
            prog_name);

    if (cur_user)
        free(cur_user);
    return EXIT_OK;

}