xref: /freebsd/usr.bin/yes/yes.c (revision f3aff7c91bd451d300ffd37ddce5a1fdbe802123)
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