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      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 }
     76