xref: /freebsd/usr.bin/yes/yes.c (revision f5147e312f43a9050468de539aeafa072caa1a60)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1987, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #ifndef lint
33 static const char copyright[] =
34 "@(#) Copyright (c) 1987, 1993\n\
35 	The Regents of the University of California.  All rights reserved.\n";
36 #endif /* not lint */
37 
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)yes.c	8.1 (Berkeley) 6/6/93";
41 #else
42 static const char rcsid[] = "$FreeBSD$";
43 #endif
44 #endif /* not lint */
45 
46 #include <capsicum_helpers.h>
47 #include <err.h>
48 #include <stdio.h>
49 #include <string.h>
50 #include <unistd.h>
51 
52 int
53 main(int argc, char **argv)
54 {
55 	char buf[8192];
56 	char y[2] = { 'y', '\n' };
57 	char * exp = y;
58 	size_t buflen = 0;
59 	size_t explen = sizeof(y);
60 	size_t more;
61 	ssize_t ret;
62 
63 	if (caph_limit_stdio() < 0 || (cap_enter() < 0 && errno != ENOSYS))
64 		err(1, "capsicum");
65 
66 	if (argc > 1) {
67 		exp = argv[1];
68 		explen = strlen(exp) + 1;
69 		exp[explen - 1] = '\n';
70 	}
71 
72 	if (explen <= sizeof(buf)) {
73 		while (buflen < sizeof(buf) - explen) {
74 			memcpy(buf + buflen, exp, explen);
75 			buflen += explen;
76 		}
77 		exp = buf;
78 		explen = buflen;
79 	}
80 
81 	more = explen;
82 	while ((ret = write(STDOUT_FILENO, exp + (explen - more), more)) > 0)
83 		if ((more -= ret) == 0)
84 			more = explen;
85 
86 	err(1, "stdout");
87 	/*NOTREACHED*/
88 }
89