/*      $OpenBSD: lastcomm.c,v 1.36 2024/02/25 00:07:13 deraadt Exp $   */
/*      $NetBSD: lastcomm.c,v 1.9 1995/10/22 01:43:42 ghudson Exp $     */

/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/types.h>
#include <sys/stat.h>
#include <sys/acct.h>

#include <ctype.h>
#include <err.h>
#include <fcntl.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>
#include <pwd.h>
#include "pathnames.h"

time_t   expand(u_int);
char    *flagbits(int);
char    *getdev(dev_t);
int      requested(char *[], struct acct *);
void     usage(void);

#define SECSPERMIN      (60)
#define SECSPERHOUR     (60 * 60)

int
main(int argc, char *argv[])
{
        char *p;
        struct acct ab;
        struct stat sb;
        FILE *fp;
        off_t size;
        time_t t;
        double delta;
        int ch;
        char *acctfile;

        if (pledge("stdio rpath getpw", NULL) == -1)
                err(1, "pledge");

        acctfile = _PATH_ACCT;
        while ((ch = getopt(argc, argv, "f:")) != -1)
                switch(ch) {
                case 'f':
                        acctfile = optarg;
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        /* Open the file. */
        if ((fp = fopen(acctfile, "r")) == NULL || fstat(fileno(fp), &sb))
                err(1, "%s", acctfile);

        /*
         * Round off to integral number of accounting records, probably
         * not necessary, but it doesn't hurt.
         */
        size = sb.st_size - sb.st_size % sizeof(struct acct);

        /* Check if any records to display. */
        if (size < sizeof(struct acct))
                exit(0);

        /*
         * Seek to before the last entry in the file; use lseek(2) in case
         * the file is bigger than a "long".
         */
        size -= sizeof(struct acct);
        if (lseek(fileno(fp), size, SEEK_SET) == -1)
                err(1, "%s", acctfile);

        for (;;) {
                char commpid[sizeof(ab.ac_comm) + 13];

                if (fread(&ab, sizeof(struct acct), 1, fp) != 1)
                        err(1, "%s", acctfile);

                if (ab.ac_comm[0] == '\0') {
                        ab.ac_comm[0] = '?';
                        ab.ac_comm[1] = '\0';
                } else
                        for (p = &ab.ac_comm[0];
                            p < &ab.ac_comm[sizeof ab.ac_comm] && *p; ++p)
                                if (!isprint((unsigned char)*p))
                                        *p = '?';
                snprintf(commpid, sizeof(commpid), "%s[%d]",
                    ab.ac_comm, ab.ac_pid);
                if (!*argv || requested(argv, &ab)) {
                        t = expand(ab.ac_utime) + expand(ab.ac_stime);
                        (void)printf("%-*.*s %-7s %-*.*s %-*.*s %6.2f secs %.16s",
                            (int)sizeof commpid,
                            (int)sizeof commpid,
                            commpid, flagbits(ab.ac_flag), UT_NAMESIZE,
                            UT_NAMESIZE, user_from_uid(ab.ac_uid, 0),
                            UT_LINESIZE, UT_LINESIZE, getdev(ab.ac_tty),
                            t / (double)AHZ, ctime(&ab.ac_btime));
                        delta = expand(ab.ac_etime) / (double)AHZ;
                        printf(" (%1.0f:%02.0f:%05.2f)\n",
                            delta / SECSPERHOUR,
                            fmod(delta, (double)SECSPERHOUR) / SECSPERMIN,
                            fmod(delta, (double)SECSPERMIN));
                }

                if (size == 0)
                        break;
                /* seek to previous entry */
                if (fseek(fp, 2 * -(long)sizeof(struct acct), SEEK_CUR) == -1)
                        err(1, "%s", acctfile);
                size -= sizeof(struct acct);
        }
        exit(0);
}

time_t
expand(u_int t)
{
        time_t nt;

        nt = t & 017777;
        t >>= 13;
        while (t) {
                t--;
                nt <<= 3;
        }
        return (nt);
}

char *
flagbits(int f)
{
        static char flags[20] = "-";
        char *p;

#define BIT(flag, ch)   if (f & flag) *p++ = ch

        p = flags + 1;
        BIT(AFORK, 'F');
        BIT(AMAP, 'M');
        BIT(ACORE, 'D');
        BIT(AXSIG, 'X');
        BIT(APLEDGE, 'P');
        BIT(ATRAP, 'T');
        BIT(AUNVEIL, 'U');
        BIT(APINSYS, 'S');
        BIT(ABTCFI, 'B');
        *p = '\0';
        return (flags);
}

int
requested(char *argv[], struct acct *acp)
{
        do {
                if (!strcmp(user_from_uid(acp->ac_uid, 0), *argv))
                        return (1);
                if (!strcmp(getdev(acp->ac_tty), *argv))
                        return (1);
                if (!strncmp(acp->ac_comm, *argv, sizeof acp->ac_comm))
                        return (1);
        } while (*++argv);
        return (0);
}

char *
getdev(dev_t dev)
{
        static dev_t lastdev = (dev_t)-1;
        static char *lastname;

        if (dev == -1)                          /* Special case. */
                return ("__");
        if (dev == lastdev)                     /* One-element cache. */
                return (lastname);
        lastdev = dev;
        if ((lastname = devname(dev, S_IFCHR)) == NULL)
                lastname = "??";
        return (lastname);
}

void
usage(void)
{
        (void)fprintf(stderr,
            "usage: lastcomm [-f file] [command ...] [user ...] [terminal ...]\n");
        exit(1);
}