ucbcmd/users/users.c

/*
 * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/*
 * users
 */

#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
#include <utmpx.h>
#include <string.h>

static char **names;
static char **namp;

static int scmp(const void *p, const void *q);
static void summary(void);

int
main(int argc, char **argv)
{
    int nusers = 0;
    int bufflen = BUFSIZ;
    struct utmpx *utmpx;

    if (argc == 2)
        if (!utmpxname(argv[1])) {
            (void) fprintf(stderr, "Filename is too long\n");
            exit(1);
        }

    names = namp = (char **)realloc((void *)NULL, BUFSIZ * sizeof (char *));

    setutxent();

    while ((utmpx = getutxent()) != NULL) {
        if (utmpx->ut_name[0] == '\0')
            continue;
        if (utmpx->ut_type != USER_PROCESS)
            continue;
        if (nonuserx(*utmpx))
            continue;
        if (nusers == bufflen) {
            bufflen *= 2;
            names = (char **)realloc(names,
                bufflen * sizeof (char *));
            namp = names + nusers;
        }
        *namp++ = strndup(utmpx->ut_name, sizeof (utmpx->ut_name));
        nusers++;
    }

    endutxent();

    summary();
    return (0);
}

static int
scmp(const void *p, const void *q)
{
    return (strcmp((char *)p, (char *)q));
}

static void
summary(void)
{
    register char **p;

    qsort(names, namp - names, sizeof (names[0]), scmp);
    for (p = names; p < namp; p++) {
        if (p != names)
            (void) putchar(' ');
        (void) fputs(*p, stdout);
    }
    if (namp != names)      /* at least one user */
        (void) putchar('\n');
}