lib/libc/ssp/gets_chk.c

   1 /*      $NetBSD: gets_chk.c,v 1.7 2013/10/04 20:49:16 christos Exp $    */
   2
   3 /*-
   4  * Copyright (c) 2006 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 #include <sys/cdefs.h>
  32 __RCSID("$NetBSD: gets_chk.c,v 1.7 2013/10/04 20:49:16 christos Exp $");
  33
  34 /*LINTLIBRARY*/
  35
  36 #include <ssp/ssp.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <limits.h>
  40 #include <stdlib.h>
  41 #include <ssp/stdio.h>
  42
  43 extern char *__gets(char *);
  44 #undef gets
  45
  46 char *
  47 __gets_chk(char * __restrict buf, size_t slen)
  48 {
  49         char *abuf;
  50         size_t len;
  51
  52         if (slen >= (size_t)INT_MAX)
  53                 return __gets(buf);
  54
  55         if ((abuf = malloc(slen + 1)) == NULL)
  56                 return __gets(buf);
  57
  58         if (fgets(abuf, (int)(slen + 1), stdin) == NULL) {
  59                 free(abuf);
  60                 return NULL;
  61         }
  62
  63         len = strlen(abuf);
  64         if (len > 0 && abuf[len - 1] == '\n')
  65                 --len;
  66
  67         if (len >= slen)
  68                 __chk_fail();
  69
  70         (void)memcpy(buf, abuf, len);
  71
  72         buf[len] = '\0';
  73         free(abuf);
  74         return buf;
  75 }