/*************************************************************************\
*                  Copyright (C) Michael Kerrisk, 2026.                   *
*                                                                         *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU General Public License as published by the   *
* Free Software Foundation, either version 3 or (at your option) any      *
* later version. This program is distributed without any warranty.  See   *
* the file COPYING.gpl-v3 for details.                                    *
\*************************************************************************/

/* view_lastlog.c

   Display lastlogin entries for users named on command line.

   This program is Linux-specific.
*/
#include <time.h>
#include <lastlog.h>
#include <paths.h>                      /* Definition of _PATH_LASTLOG */
#include <fcntl.h>
#include "ugid_functions.h"             /* Declaration of userIdFromName() */
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    struct lastlog llog;
    int fd, j;
    uid_t uid;

    if (argc > 1 && strcmp(argv[1], "--help") == 0)
        usageErr("%s [username...]\n", argv[0]);

    fd = open(_PATH_LASTLOG, O_RDONLY);
    if (fd == -1)
        errExit("open");

    for (j = 1; j < argc; j++) {
        uid = userIdFromName(argv[j]);
        if (uid == (uid_t) -1) {
            printf("No such user: %s\n", argv[j]);
            continue;
        }

        if (lseek(fd, uid * sizeof(struct lastlog), SEEK_SET) == -1)
            errExit("lseek");

        if (read(fd, &llog, sizeof(struct lastlog)) <= 0) {
            printf("read failed for %s\n", argv[j]);    /* EOF or error */
            continue;
        }

        time_t ll_time = llog.ll_time;
        printf("%-8.8s %-6.6s %-20.20s %s", argv[j], llog.ll_line,
                llog.ll_host, ctime(&ll_time));
    }

    close(fd);
    exit(EXIT_SUCCESS);
}