1 /* $OpenBSD: random.c,v 1.12 2009/10/27 23:59:26 deraadt Exp $ */ 2 /* $NetBSD: random.c,v 1.3 1995/04/22 07:44:05 cgd Exp $ */ 3 4 /* 5 * Copyright (c) 1994 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Guy Harris at Network Appliance Corp. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/types.h> 37 38 #include <dev/rndvar.h> 39 40 #include <err.h> 41 #include <errno.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <time.h> 45 #include <unistd.h> 46 #include <limits.h> 47 48 void usage(void); 49 50 int 51 main(int argc, char *argv[]) 52 { 53 double denom; 54 int ch, random_exit, selected, unbuffer_output; 55 char *ep; 56 57 random_exit = unbuffer_output = 0; 58 while ((ch = getopt(argc, argv, "erh")) != -1) 59 switch (ch) { 60 case 'e': 61 random_exit = 1; 62 break; 63 case 'r': 64 unbuffer_output = 1; 65 break; 66 default: 67 case '?': case 'h': 68 usage(); 69 /* NOTREACHED */ 70 } 71 72 argc -= optind; 73 argv += optind; 74 75 switch (argc) { 76 case 0: 77 denom = 2; 78 break; 79 case 1: 80 errno = 0; 81 denom = strtod(*argv, &ep); 82 if (errno == ERANGE) 83 err(1, "%s", *argv); 84 if (denom == 0 || *ep != '\0') 85 errx(1, "denominator is not valid."); 86 break; 87 default: 88 usage(); 89 /* NOTREACHED */ 90 } 91 92 /* Compute a random exit status between 0 and denom - 1. */ 93 if (random_exit) 94 return (arc4random_uniform(denom)); 95 96 /* 97 * Act as a filter, randomly choosing lines of the standard input 98 * to write to the standard output. 99 */ 100 if (unbuffer_output) 101 setbuf(stdout, NULL); 102 103 /* 104 * Select whether to print the first line. (Prime the pump.) 105 * We find a random number between 0 and denom - 1 and, if it's 106 * 0 (which has a 1 / denom chance of being true), we select the 107 * line. 108 */ 109 selected = arc4random_uniform(denom) == 0; 110 while ((ch = getchar()) != EOF) { 111 if (selected) 112 (void)putchar(ch); 113 if (ch == '\n') { 114 /* End of that line. See if we got an error. */ 115 if (ferror(stdout)) 116 err(2, "stdout"); 117 118 /* Now see if the next line is to be printed. */ 119 selected = arc4random_uniform(denom) == 0; 120 } 121 } 122 if (ferror(stdin)) 123 err(2, "stdin"); 124 exit (0); 125 } 126 127 void 128 usage(void) 129 { 130 131 (void)fprintf(stderr, "usage: random [-er] [denominator]\n"); 132 exit(1); 133 } 134