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 <limits.h>
35 #include <stdio.h>
36 #include <string.h>
37 #include <unistd.h>
38
39 /*
40 * Default expletive
41 */
42 #define EXP "y\n"
43 #define EXPLEN strlen(EXP)
44
45 /*
46 * Optimum and maximum buffer size. The optimum is just a little less
47 * than the default value of kern.ipc.pipe_mindirect; writing more than
48 * that is significantly slower, but we want to get as close as possible
49 * to minimize the number of system calls. The maximum is enough for a
50 * maximal command line plus a newline and terminating NUL.
51 */
52 #define OPTBUF 8190
53 #define MAXBUF (ARG_MAX + 2)
54
55 int
main(int argc,char ** argv)56 main(int argc, char **argv)
57 {
58 static char buf[MAXBUF] = EXP;
59 char *end = buf + sizeof(buf), *exp, *pos = buf + EXPLEN;
60 size_t buflen, explen = EXPLEN;
61 ssize_t wlen = 0;
62
63 if (caph_limit_stdio() < 0 || caph_enter() < 0)
64 err(1, "capsicum");
65
66 argc -= 1;
67 argv += 1;
68
69 /* Assemble the expletive */
70 if (argc > 0) {
71 /* Copy positional arguments into expletive buffer */
72 for (pos = buf, end = buf + sizeof(buf);
73 argc > 0 && pos < end; argc--, argv++) {
74 /* Separate with spaces */
75 if (pos > buf)
76 *pos++ = ' ';
77 exp = *argv;
78 while (*exp != '\0' && pos < end)
79 *pos++ = *exp++;
80 }
81 /* This should not be possible, but check anyway */
82 if (pos > end - 2)
83 pos = end - 2;
84 *pos++ = '\n';
85 explen = pos - buf;
86 }
87
88 /*
89 * Double until we're past OPTBUF, then reduce buflen to exactly
90 * OPTBUF. It doesn't matter if that's not a multiple of explen;
91 * the modulo operation in the write loop will take care of that.
92 */
93 for (buflen = explen; buflen < OPTBUF; pos += buflen, buflen += buflen)
94 memcpy(pos, buf, buflen);
95 if (explen < OPTBUF && buflen > OPTBUF)
96 buflen = OPTBUF;
97
98 /* Dump it to stdout */
99 end = (pos = buf) + buflen;
100 do {
101 pos = buf + (pos - buf + wlen) % explen;
102 wlen = write(STDOUT_FILENO, pos, end - pos);
103 } while (wlen > 0);
104 err(1, "stdout");
105 /*NOTREACHED*/
106 }
107