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 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