getutxent.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/stat.h>
  34 #include <errno.h>
  35 #include <stdio.h>
  36 #include <string.h>
  37 #include <utmpx.h>
  38 #include "utxdb.h"
  39
  40 #include "utmpx-defines.h"
  41 #define rounddown(x, y) (((x) / (y)) * (y))
  42
  43 #ifdef __NO_TLS
  44 static FILE *uf = NULL;
  45 static int udb;
  46 #else
  47 static _Thread_local FILE *uf = NULL;
  48 static _Thread_local int udb;
  49 #endif
  50
  51 int
  52 setutxdb(int db, const char *file)
  53 {
  54         struct stat sb;
  55
  56         switch (db) {
  57         case UTXDB_ACTIVE:
  58                 if (file == NULL)
  59                         file = _PATH_UTX_ACTIVE;
  60                 break;
  61         case UTXDB_LASTLOGIN:
  62                 if (file == NULL)
  63                         file = _PATH_UTX_LASTLOGIN;
  64                 break;
  65         case UTXDB_LOG:
  66                 if (file == NULL)
  67                         file = _PATH_UTX_LOG;
  68                 break;
  69         default:
  70                 errno = EINVAL;
  71                 return (-1);
  72         }
  73
  74         if (uf != NULL)
  75                 fclose(uf);
  76         uf = fopen(file, "re");
  77         if (uf == NULL)
  78                 return (-1);
  79
  80         if (db != UTXDB_LOG) {
  81                 /* Safety check: never use broken files. */
  82                 if (fstat(fileno(uf), &sb) != -1 &&
  83                     sb.st_size % sizeof(struct futx) != 0) {
  84                         fclose(uf);
  85                         uf = NULL;
  86                         errno = EFTYPE;
  87                         return (-1);
  88                 }
  89                 /* Prevent reading of partial records. */
  90                 (void)setvbuf(uf, NULL, _IOFBF,
  91                     rounddown(BUFSIZ, sizeof(struct futx)));
  92         }
  93
  94         udb = db;
  95         return (0);
  96 }