1 /* $OpenBSD: random.c,v 1.11 2008/04/13 00:22:16 djm 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 #ifndef lint 37 static char copyright[] = 38 "@(#) Copyright (c) 1994\n\ 39 The Regents of the University of California. All rights reserved.\n"; 40 #endif /* not lint */ 41 42 #ifndef lint 43 #if 0 44 static char sccsid[] = "@(#)random.c 8.5 (Berkeley) 4/5/94"; 45 #else 46 static char rcsid[] = "$OpenBSD: random.c,v 1.11 2008/04/13 00:22:16 djm Exp $"; 47 #endif 48 #endif /* not lint */ 49 50 #include <sys/types.h> 51 52 #include <dev/rndvar.h> 53 54 #include <err.h> 55 #include <errno.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <time.h> 59 #include <unistd.h> 60 #include <limits.h> 61 62 void usage(void); 63 64 int 65 main(int argc, char *argv[]) 66 { 67 double denom; 68 int ch, random_exit, selected, unbuffer_output; 69 char *ep; 70 71 random_exit = unbuffer_output = 0; 72 while ((ch = getopt(argc, argv, "erh")) != -1) 73 switch (ch) { 74 case 'e': 75 random_exit = 1; 76 break; 77 case 'r': 78 unbuffer_output = 1; 79 break; 80 default: 81 case '?': case 'h': 82 usage(); 83 /* NOTREACHED */ 84 } 85 86 argc -= optind; 87 argv += optind; 88 89 switch (argc) { 90 case 0: 91 denom = 2; 92 break; 93 case 1: 94 errno = 0; 95 denom = strtod(*argv, &ep); 96 if (errno == ERANGE) 97 err(1, "%s", *argv); 98 if (denom == 0 || *ep != '\0') 99 errx(1, "denominator is not valid."); 100 break; 101 default: 102 usage(); 103 /* NOTREACHED */ 104 } 105 106 /* Compute a random exit status between 0 and denom - 1. */ 107 if (random_exit) 108 return (arc4random_uniform(denom)); 109 110 /* 111 * Act as a filter, randomly choosing lines of the standard input 112 * to write to the standard output. 113 */ 114 if (unbuffer_output) 115 setbuf(stdout, NULL); 116 117 /* 118 * Select whether to print the first line. (Prime the pump.) 119 * We find a random number between 0 and denom - 1 and, if it's 120 * 0 (which has a 1 / denom chance of being true), we select the 121 * line. 122 */ 123 selected = arc4random_uniform(denom) == 0; 124 while ((ch = getchar()) != EOF) { 125 if (selected) 126 (void)putchar(ch); 127 if (ch == '\n') { 128 /* End of that line. See if we got an error. */ 129 if (ferror(stdout)) 130 err(2, "stdout"); 131 132 /* Now see if the next line is to be printed. */ 133 selected = arc4random_uniform(denom) == 0; 134 } 135 } 136 if (ferror(stdin)) 137 err(2, "stdin"); 138 exit (0); 139 } 140 141 void 142 usage(void) 143 { 144 145 (void)fprintf(stderr, "usage: random [-er] [denominator]\n"); 146 exit(1); 147 } 148