xref: /freebsd/usr.bin/yes/yes.c (revision 8aac90f18aef7c9eea906c3ff9a001ca7b94f375)
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 #include <capsicum_helpers.h>
33 #include <err.h>
34 #include <stdio.h>
35 #include <string.h>
36 #include <unistd.h>
37 
38 int
39 main(int argc, char **argv)
40 {
41 	char buf[8192];
42 	char y[2] = { 'y', '\n' };
43 	char * exp = y;
44 	size_t buflen = 0;
45 	size_t explen = sizeof(y);
46 	size_t more;
47 	ssize_t ret;
48 
49 	if (caph_limit_stdio() < 0 || caph_enter() < 0)
50 		err(1, "capsicum");
51 
52 	if (argc > 1) {
53 		exp = argv[1];
54 		explen = strlen(exp) + 1;
55 		exp[explen - 1] = '\n';
56 	}
57 
58 	if (explen <= sizeof(buf)) {
59 		while (buflen < sizeof(buf) - explen) {
60 			memcpy(buf + buflen, exp, explen);
61 			buflen += explen;
62 		}
63 		exp = buf;
64 		explen = buflen;
65 	}
66 
67 	more = explen;
68 	while ((ret = write(STDOUT_FILENO, exp + (explen - more), more)) > 0)
69 		if ((more -= ret) == 0)
70 			more = explen;
71 
72 	err(1, "stdout");
73 	/*NOTREACHED*/
74 }
75