/* $OpenBSD: random.c,v 1.8 2002/05/31 03:40:01 pjanzen Exp $ */ /* $NetBSD: random.c,v 1.3 1995/04/22 07:44:05 cgd Exp $ */ /* * Copyright (c) 1994 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Guy Harris at Network Appliance Corp. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef lint static char copyright[] = "@(#) Copyright (c) 1994\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint #if 0 static char sccsid[] = "@(#)random.c 8.5 (Berkeley) 4/5/94"; #else static char rcsid[] = "$OpenBSD: random.c,v 1.8 2002/05/31 03:40:01 pjanzen Exp $"; #endif #endif /* not lint */ #include <sys/types.h> #include <dev/rndvar.h> #include <err.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <time.h> #include <unistd.h> #include <limits.h> void usage(void); int main(argc, argv) int argc; char *argv[]; { double denom; int ch, random_exit, selected, unbuffer_output; char *ep; random_exit = unbuffer_output = 0; while ((ch = getopt(argc, argv, "erh")) != -1) switch (ch) { case 'e': random_exit = 1; break; case 'r': unbuffer_output = 1; break; default: case '?': case 'h': usage(); /* NOTREACHED */ } argc -= optind; argv += optind; switch (argc) { case 0: denom = 2; break; case 1: errno = 0; denom = strtod(*argv, &ep); if (errno == ERANGE) err(1, "%s", *argv); if (denom == 0 || *ep != '\0') errx(1, "denominator is not valid."); break; default: usage(); /* NOTREACHED */ } /* Compute a random exit status between 0 and denom - 1. */ if (random_exit) return (arc4random() % (u_int32_t)denom); /* * Act as a filter, randomly choosing lines of the standard input * to write to the standard output. */ if (unbuffer_output) setbuf(stdout, NULL); /* * Select whether to print the first line. (Prime the pump.) * We find a random number between 0 and denom - 1 and, if it's * 0 (which has a 1 / denom chance of being true), we select the * line. */ selected = (int)(arc4random() % (u_int32_t)denom) == 0; while ((ch = getchar()) != EOF) { if (selected) (void)putchar(ch); if (ch == '\n') { /* End of that line. See if we got an error. */ if (ferror(stdout)) err(2, "stdout"); /* Now see if the next line is to be printed. */ selected = (int)(arc4random() % (u_int32_t)denom) == 0; } } if (ferror(stdin)) err(2, "stdin"); exit (0); } void usage() { (void)fprintf(stderr, "usage: random [-er] [denominator]\n"); exit(1); }