/*-
 * Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/endian.h>
#include <sys/param.h>

#include <err.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <utmpx.h>

struct outmp {
        char    ut_line[8];
        char    ut_user[16];
        char    ut_host[16];
        time_t  ut_time;
};

static const char vers[] = "utmpx-2.00";

static void
usage(void)
{

        fprintf(stderr, "usage: wtmpcvt input output\n");
        exit(1);
}

static void
outmp_to_utmpx(const struct outmp *ui, struct utmpx *uo)
{

        memset(uo, 0, sizeof *uo);
#define COPY_STRING(field) do {                                         \
        strncpy(uo->ut_ ## field, ui->ut_ ## field,                     \
            MIN(sizeof uo->ut_ ## field, sizeof ui->ut_ ## field));     \
} while (0)
#define COPY_LINE_TO_ID() do {                                          \
        strncpy(uo->ut_id, ui->ut_line,                                 \
            MIN(sizeof uo->ut_id, sizeof ui->ut_line));                 \
} while (0)
#define MATCH(field, value)     (strncmp(ui->ut_ ## field, (value),     \
                                        sizeof(ui->ut_ ## field)) == 0)
        if (MATCH(user, "reboot") && MATCH(line, "~")) {
                uo->ut_type = INIT_PROCESS;
                COPY_STRING(user);
                COPY_STRING(line);
        } else if (MATCH(user, "date") && MATCH(line, "|")) {
                uo->ut_type = OLD_TIME;
        } else if (MATCH(user, "date") && MATCH(line, "{")) {
                uo->ut_type = NEW_TIME;
        } else if (MATCH(user, "shutdown") && MATCH(line, "~")) {
                uo->ut_type = INIT_PROCESS;
                COPY_STRING(user);
                COPY_STRING(line);
        } else if (MATCH(user, "") && MATCH(host, "") && !MATCH(line, "")) {
                uo->ut_type = DEAD_PROCESS;
                COPY_LINE_TO_ID();
        } else if (!MATCH(user, "") && !MATCH(line, "") && ui->ut_time != 0) {
                uo->ut_type = USER_PROCESS;
                COPY_STRING(user);
                COPY_STRING(line);
                COPY_STRING(host);
                COPY_LINE_TO_ID();
        } else {
                uo->ut_type = EMPTY;
                return;
        }
#undef COPY_STRING
#undef COPY_LINE_TO_ID
#undef MATCH

        uo->ut_tv.tv_sec = ui->ut_time;
        uo->ut_tv.tv_usec = 0;
}

int
main(int argc, char *argv[])
{
        FILE *in, *out;
        struct outmp ui;
        struct utmpx uo;

        if (argc != 3)
                usage();

        /* Open files. */
        in = fopen(argv[1], "r");
        if (in == NULL)
                err(1, "%s", argv[1]);
        out = fopen(argv[2], "w");
        if (out == NULL)
                err(1, "%s", argv[2]);

        /* Write signature. */
        memset(&uo, 0, sizeof uo);
        uo.ut_type = SIGNATURE;
        memcpy(uo.ut_user, vers, sizeof(vers));
        fwrite(&uo, sizeof uo, 1, out);

        /* Process entries. */
        while (fread(&ui, sizeof ui, 1, in) == 1) {
                outmp_to_utmpx(&ui, &uo);
                if (uo.ut_type == EMPTY)
                        continue;

                /* Write new entry to output file. */
                fwrite(&uo, sizeof uo, 1, out);
        }

        fclose(in);
        fclose(out);
        return (0);
}