/***
  This file is part of systemd.

  Copyright 2014 Ivan Shapovalov

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>

#include "systemd-basic/alloc-util.h"
#include "systemd-basic/fileio.h"
#include "systemd-basic/log.h"
#include "systemd-basic/util.h"

int main(int argc, char *argv[]) {
        struct stat st;
        const char *device;
        _cleanup_free_ char *major_minor = NULL;
        int r;

        if (argc != 2) {
                log_error("This program expects one argument.");
                return EXIT_FAILURE;
        }

        log_set_target(LOG_TARGET_AUTO);
        log_parse_environment();
        log_open();

        umask(0022);

        /* Refuse to run unless we are in an initrd() */
        if (!in_initrd())
                return EXIT_SUCCESS;

        device = argv[1];

        if (stat(device, &st) < 0) {
                log_error_errno(errno, "Failed to stat '%s': %m", device);
                return EXIT_FAILURE;
        }

        if (!S_ISBLK(st.st_mode)) {
                log_error("Resume device '%s' is not a block device.", device);
                return EXIT_FAILURE;
        }

        if (asprintf(&major_minor, "%d:%d", major(st.st_rdev), minor(st.st_rdev)) < 0) {
                log_oom();
                return EXIT_FAILURE;
        }

        r = write_string_file("/sys/power/resume", major_minor, WRITE_STRING_FILE_CREATE);
        if (r < 0) {
                log_error_errno(r, "Failed to write '%s' to /sys/power/resume: %m", major_minor);
                return EXIT_FAILURE;
        }

        /*
         * The write above shall not return.
         *
         * However, failed resume is a normal condition (may mean that there is
         * no hibernation image).
         */

        log_info("Could not resume from '%s' (%s).", device, major_minor);
        return EXIT_SUCCESS;
}