xref: /src/lib/libc/stdio/gets.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)gets.c	5.3 (Berkeley) 1/20/91";*/
static char *rcsid = "$Id: gets.c,v 1.4 1994/04/24 01:01:29 mycroft Exp $";
#endif /* LIBC_SCCS and not lint */

#include <unistd.h>
#include <stdio.h>
#include <sys/uio.h>

char *
gets(buf)
	char *buf;
{
	register int c;
	register char *s;
	static int warned;
	static char w[] =
	    ": warning: this program uses gets(), which is unsafe.\r\n";

	if (!warned) {
		struct iovec iov[2];
		extern char *__progname;	/* in crt0 */

		iov[0].iov_base = __progname;
		iov[0].iov_len = strlen(__progname);
		iov[1].iov_base = w;
		iov[1].iov_len = strlen(w);
		(void) writev(STDERR_FILENO, iov, 2);
		warned = 1;
	}

	for (s = buf; (c = getchar()) != '\n';)
		if (c == EOF)
			if (s == buf)
				return (NULL);
			else
				break;
		else
			*s++ = c;
	*s = 0;
	return (buf);
}