lib/libc/gen/utmp.c

   1 /*      $NetBSD: utmp.c,v 1.8 2009/01/11 02:46:27 christos Exp $         */
   2
   3 /*-
   4  * Copyright (c) 2002 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Christos Zoulas.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include "namespace.h"
  33 #include <sys/types.h>
  34 #include <sys/param.h>
  35 #include <stdio.h>
  36 #include <string.h>
  37 #include <time.h>
  38 #include <utmp.h>
  39 #include <sys/stat.h>
  40
  41 static struct utmp utmp;
  42 static FILE *ut;
  43 static char utfile[MAXPATHLEN] = _PATH_UTMP;
  44
  45 void
  46 setutent(void)
  47 {
  48         if (ut == NULL)
  49                 return;
  50         (void)fseeko(ut, (off_t)0, SEEK_SET);
  51 }
  52
  53 struct utmp *
  54 getutent(void)
  55 {
  56         if (ut == NULL) {
  57                 struct stat st;
  58                 off_t numentries;
  59                 if ((ut = fopen(utfile, "r")) == NULL)
  60                         return NULL;
  61                 if (fstat(fileno(ut), &st) == -1)
  62                         goto out;
  63                 /*
  64                  * If we have a an old version utmp file bail.
  65                  */
  66                 numentries = st.st_size / sizeof(utmp);
  67                 if ((off_t)(numentries * sizeof(utmp)) != st.st_size)
  68                         goto out;
  69         }
  70         if (fread(&utmp, sizeof(utmp), 1, ut) == 1)
  71                 return &utmp;
  72 out:
  73         (void)fclose(ut);
  74         return NULL;
  75 }
  76
  77 void
  78 endutent(void)
  79 {
  80         if (ut != NULL) {
  81                 (void)fclose(ut);
  82                 ut = NULL;
  83         }
  84 }
  85
  86 int
  87 utmpname(const char *fname)
  88 {
  89         size_t len = strlen(fname);
  90
  91         if (len >= sizeof(utfile))
  92                 return 0;
  93
  94         /* must not end in x! */
  95         if (fname[len - 1] == 'x')
  96                 return 0;
  97
  98         (void)strlcpy(utfile, fname, sizeof(utfile));
  99         endutent();
 100         return 1;
 101 }