/*      $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

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