xref: /freebsd/usr.bin/yes/yes.c (revision 38069501)
1 /*
2  * Copyright (c) 1987, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #ifndef lint
31 static const char copyright[] =
32 "@(#) Copyright (c) 1987, 1993\n\
33 	The Regents of the University of California.  All rights reserved.\n";
34 #endif /* not lint */
35 
36 #ifndef lint
37 #if 0
38 static char sccsid[] = "@(#)yes.c	8.1 (Berkeley) 6/6/93";
39 #else
40 static const char rcsid[] = "$FreeBSD$";
41 #endif
42 #endif /* not lint */
43 
44 #include <capsicum_helpers.h>
45 #include <err.h>
46 #include <stdio.h>
47 #include <string.h>
48 #include <unistd.h>
49 
50 int
51 main(int argc, char **argv)
52 {
53 	char buf[8192];
54 	char y[2] = { 'y', '\n' };
55 	char * exp = y;
56 	size_t buflen = 0;
57 	size_t explen = sizeof(y);
58 	size_t more;
59 	ssize_t ret;
60 
61 	if (caph_limit_stdio() < 0 || (cap_enter() < 0 && errno != ENOSYS))
62 		err(1, "capsicum");
63 
64 	if (argc > 1) {
65 		exp = argv[1];
66 		explen = strlen(exp) + 1;
67 		exp[explen - 1] = '\n';
68 	}
69 
70 	if (explen <= sizeof(buf)) {
71 		while (buflen < sizeof(buf) - explen) {
72 			memcpy(buf + buflen, exp, explen);
73 			buflen += explen;
74 		}
75 		exp = buf;
76 		explen = buflen;
77 	}
78 
79 	more = explen;
80 	while ((ret = write(STDOUT_FILENO, exp + (explen - more), more)) > 0)
81 		if ((more -= ret) == 0)
82 			more = explen;
83 
84 	err(1, "stdout");
85 	/*NOTREACHED*/
86 }
87