/*      $NetBSD: utmpentry.c,v 1.22 2021/02/26 02:45:43 christos Exp $  */

/*-
 * Copyright (c) 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: utmpentry.c,v 1.22 2021/02/26 02:45:43 christos Exp $");
#endif

#include <sys/stat.h>

#include <time.h>
#include <string.h>
#include <err.h>
#include <stdlib.h>

#ifdef SUPPORT_UTMP
#include <utmp.h>
#endif
#ifdef SUPPORT_UTMPX
#include <utmpx.h>
#endif

#include "utmpentry.h"


/* Fail the compile if x is not true, by constructing an illegal type. */
#define COMPILE_ASSERT(x) /*LINTED null effect */ \
        ((void)sizeof(struct { unsigned : ((x) ? 1 : -1); }))


#ifdef SUPPORT_UTMP
static void getentry(struct utmpentry *, struct utmp *);
static struct timespec utmptime = {0, 0};
#endif
#ifdef SUPPORT_UTMPX
static void getentryx(struct utmpentry *, struct utmpx *);
static struct timespec utmpxtime = {0, 0};
#endif
#if defined(SUPPORT_UTMPX) || defined(SUPPORT_UTMP)
static int setup(const char *);
static void adjust_size(struct utmpentry *e);
#endif

size_t maxname = 8, maxline = 8, maxhost = 16;
int etype = 1 << USER_PROCESS;
static size_t numutmp = 0;
static struct utmpentry *ehead;

#if defined(SUPPORT_UTMPX) || defined(SUPPORT_UTMP)
static void
adjust_size(struct utmpentry *e)
{
        size_t max;

        if ((max = strlen(e->name)) > maxname)
                maxname = max;
        if ((max = strlen(e->line)) > maxline)
                maxline = max;
        if ((max = strlen(e->host)) > maxhost)
                maxhost = max;
}

static int
setup(const char *fname)
{
        int what = 3;
        struct stat st;
        const char *sfname;

        if (fname != NULL) {
                size_t len = strlen(fname);
                if (len == 0)
                        errx(1, "Filename cannot be 0 length.");
                what = fname[len - 1] == 'x' ? 1 : 2;
                if (what == 1) {
#ifdef SUPPORT_UTMPX
                        if (utmpxname(fname) == 0)
                                warnx("Cannot set utmpx file to `%s'",
                                    fname);
#else
                        warnx("utmpx support not compiled in");
#endif
                } else {
#ifdef SUPPORT_UTMP
                        if (utmpname(fname) == 0)
                                warnx("Cannot set utmp file to `%s'",
                                    fname);
#else
                        warnx("utmp support not compiled in");
#endif
                }
        }
#ifdef SUPPORT_UTMPX
        if (what & 1) {
                sfname = fname ? fname : _PATH_UTMPX;
                if (stat(sfname, &st) == -1) {
                        warn("Cannot stat `%s'", sfname);
                        what &= ~1;
                } else {
                        if (timespeccmp(&st.st_mtimespec, &utmpxtime, >))
                                utmpxtime = st.st_mtimespec;
                        else
                                what &= ~1;
                }
        }
#endif
#ifdef SUPPORT_UTMP
        if (what & 2) {
                sfname = fname ? fname : _PATH_UTMP;
                if (stat(sfname, &st) == -1) {
                        warn("Cannot stat `%s'", sfname);
                        what &= ~2;
                } else {
                        if (timespeccmp(&st.st_mtimespec, &utmptime, >))
                                utmptime = st.st_mtimespec;
                        else
                                what &= ~2;
                }
        }
#endif
        return what;
}
#endif

void
endutentries(void)
{
        struct utmpentry *ep;

#ifdef SUPPORT_UTMP
        timespecclear(&utmptime);
#endif
#ifdef SUPPORT_UTMPX
        timespecclear(&utmpxtime);
#endif
        ep = ehead;
        while (ep) {
                struct utmpentry *sep = ep;
                ep = ep->next;
                free(sep);
        }
        ehead = NULL;
        numutmp = 0;
}

size_t
getutentries(const char *fname, struct utmpentry **epp)
{
#ifdef SUPPORT_UTMPX
        struct utmpx *utx;
#endif
#ifdef SUPPORT_UTMP
        struct utmp *ut;
#endif
#if defined(SUPPORT_UTMP) || defined(SUPPORT_UTMPX)
        struct utmpentry *ep;
        int what = setup(fname);
        struct utmpentry **nextp = &ehead;
        switch (what) {
        case 0:
                /* No updates */
                *epp = ehead;
                return numutmp;
        default:
                /* Need to re-scan */
                ehead = NULL;
                numutmp = 0;
        }
#endif

#ifdef SUPPORT_UTMPX
        setutxent();
        while ((what & 1) && (utx = getutxent()) != NULL) {
                if (fname == NULL && ((1 << utx->ut_type) & etype) == 0)
                        continue;
                if ((ep = calloc(1, sizeof(*ep))) == NULL) {
                        warn(NULL);
                        return 0;
                }
                getentryx(ep, utx);
                *nextp = ep;
                nextp = &(ep->next);
        }
#endif

#ifdef SUPPORT_UTMP
        setutent();
        if ((etype & (1 << USER_PROCESS)) != 0) {
                while ((what & 2) && (ut = getutent()) != NULL) {
                        if (fname == NULL && (*ut->ut_name == '\0' ||
                            *ut->ut_line == '\0'))
                                continue;
                        /* Don't process entries that we have utmpx for */
                        for (ep = ehead; ep != NULL; ep = ep->next) {
                                if (strncmp(ep->line, ut->ut_line,
                                    sizeof(ut->ut_line)) == 0)
                                        break;
                        }
                        if (ep != NULL)
                                continue;
                        if ((ep = calloc(1, sizeof(*ep))) == NULL) {
                                warn(NULL);
                                return 0;
                        }
                        getentry(ep, ut);
                        *nextp = ep;
                        nextp = &(ep->next);
                }
        }
#endif
        numutmp = 0;
#if defined(SUPPORT_UTMP) || defined(SUPPORT_UTMPX)
        if (ehead != NULL) {
                struct utmpentry *from = ehead, *save;
                
                ehead = NULL;
                while (from != NULL) {
                        for (nextp = &ehead;
                            (*nextp) && strcmp(from->line, (*nextp)->line) > 0;
                            nextp = &(*nextp)->next)
                                continue;
                        save = from;
                        from = from->next;
                        save->next = *nextp;
                        *nextp = save;
                        numutmp++;
                }
        }
        *epp = ehead;
        return numutmp;
#else
        *epp = NULL;
        return 0;
#endif
}

#ifdef SUPPORT_UTMP
static void
getentry(struct utmpentry *e, struct utmp *up)
{
        COMPILE_ASSERT(sizeof(e->name) > sizeof(up->ut_name));
        COMPILE_ASSERT(sizeof(e->line) > sizeof(up->ut_line));
        COMPILE_ASSERT(sizeof(e->host) > sizeof(up->ut_host));

        /*
         * e has just been calloc'd. We don't need to clear it or
         * append null-terminators, because its length is strictly
         * greater than the source string. Use memcpy to _read_
         * up->ut_* because they may not be terminated. For this
         * reason we use the size of the _source_ as the length
         * argument.
         */
        memcpy(e->name, up->ut_name, sizeof(up->ut_name));
        memcpy(e->line, up->ut_line, sizeof(up->ut_line));
        memcpy(e->host, up->ut_host, sizeof(up->ut_host));

        e->tv.tv_sec = up->ut_time;
        e->tv.tv_usec = 0;
        e->pid = 0;
        e->term = 0;
        e->exit = 0;
        e->sess = 0;
        e->type = USER_PROCESS;
        adjust_size(e);
}
#endif

#ifdef SUPPORT_UTMPX
static void
getentryx(struct utmpentry *e, struct utmpx *up)
{
        COMPILE_ASSERT(sizeof(e->name) > sizeof(up->ut_name));
        COMPILE_ASSERT(sizeof(e->line) > sizeof(up->ut_line));
        COMPILE_ASSERT(sizeof(e->host) > sizeof(up->ut_host));

        /*
         * e has just been calloc'd. We don't need to clear it or
         * append null-terminators, because its length is strictly
         * greater than the source string. Use memcpy to _read_
         * up->ut_* because they may not be terminated. For this
         * reason we use the size of the _source_ as the length
         * argument.
         */
        memcpy(e->name, up->ut_name, sizeof(up->ut_name));
        memcpy(e->line, up->ut_line, sizeof(up->ut_line));
        memcpy(e->host, up->ut_host, sizeof(up->ut_host));

        e->tv = up->ut_tv;
        e->pid = up->ut_pid;
        e->term = up->ut_exit.e_termination;
        e->exit = up->ut_exit.e_exit;
        e->sess = up->ut_session;
        e->type = up->ut_type;
        adjust_size(e);
}
#endif