xref: /freebsd/lib/libc/stdio/gets.c (revision 63a938566d524836885917d95bd491aa4400b181)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1990, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Chris Torek.
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  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)gets.c	8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include "namespace.h"
42 #include <unistd.h>
43 #include <stdio.h>
44 #include "un-namespace.h"
45 #include "libc_private.h"
46 #include "local.h"
47 
48 __warn_references(gets, "warning: this program uses gets(), which is unsafe.");
49 
50 char *
51 gets(char *buf)
52 {
53 	int c;
54 	char *s, *ret;
55 	static int warned;
56 	static const char w[] =
57 	    "warning: this program uses gets(), which is unsafe.\n";
58 
59 	FLOCKFILE_CANCELSAFE(stdin);
60 	ORIENT(stdin, -1);
61 	if (!warned) {
62 		(void) _write(STDERR_FILENO, w, sizeof(w) - 1);
63 		warned = 1;
64 	}
65 	for (s = buf; (c = __sgetc(stdin)) != '\n'; ) {
66 		if (c == EOF) {
67 			if (s == buf) {
68 				ret = NULL;
69 				goto end;
70 			} else
71 				break;
72 		} else
73 			*s++ = c;
74 	}
75 	*s = 0;
76 	ret = buf;
77 end:
78 	FUNLOCKFILE_CANCELSAFE();
79 	return (ret);
80 }
81