xref: /netbsd-src/lib/libc/stdio/gets.c (revision d9158b13b5dfe46201430699a3f7a235ecf28df3)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Chris Torek.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 /*static char *sccsid = "from: @(#)gets.c	5.3 (Berkeley) 1/20/91";*/
39 static char *rcsid = "$Id: gets.c,v 1.5 1994/04/24 01:05:13 mycroft Exp $";
40 #endif /* LIBC_SCCS and not lint */
41 
42 #include <unistd.h>
43 #include <stdio.h>
44 #include <sys/uio.h>
45 
46 char *
47 gets(buf)
48 	char *buf;
49 {
50 	register int c;
51 	register char *s;
52 	static int warned;
53 	static char w[] =
54 	    ": warning: this program uses gets(), which is unsafe.\r\n";
55 
56 	if (!warned) {
57 		struct iovec iov[2];
58 		extern char *__progname;	/* in crt0 */
59 
60 		iov[0].iov_base = __progname;
61 		iov[0].iov_len = strlen(__progname);
62 		iov[1].iov_base = w;
63 		iov[1].iov_len = sizeof(w) - 1;
64 		(void) writev(STDERR_FILENO, iov, 2);
65 		warned = 1;
66 	}
67 
68 	for (s = buf; (c = getchar()) != '\n';)
69 		if (c == EOF)
70 			if (s == buf)
71 				return (NULL);
72 			else
73 				break;
74 		else
75 			*s++ = c;
76 	*s = 0;
77 	return (buf);
78 }
79