diff options
Diffstat (limited to 'random/random.c')
| -rw-r--r-- | random/random.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/random/random.c b/random/random.c new file mode 100644 index 00000000..a6fe4725 --- /dev/null +++ b/random/random.c @@ -0,0 +1,148 @@ +/* + * 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 +static char sccsid[] = "@(#)random.c 8.5 (Berkeley) 4/5/94"; +#endif /* not lint */ + +#include <sys/types.h> + +#include <err.h> +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <time.h> +#include <unistd.h> + +void usage __P((void)); + +int +main(argc, argv) + int argc; + char *argv[]; +{ + extern int optind; + time_t now; + double denom; + int ch, random_exit, selected, unbuffer_output; + char *ep; + + random_exit = unbuffer_output = 0; + while ((ch = getopt(argc, argv, "er")) != EOF) + switch (ch) { + case 'e': + random_exit = 1; + break; + case 'r': + unbuffer_output = 1; + break; + default: + case '?': + 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 */ + } + + (void)time(&now); + srandom((u_int)(now + getpid())); + + /* Compute a random exit status between 0 and denom - 1. */ + if (random_exit) + return ((denom * random()) / LONG_MAX); + + /* + * 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)(denom * random() / LONG_MAX) == 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)(denom * random() / LONG_MAX) == 0; + } + } + if (ferror(stdin)) + err(2, "stdin"); + exit (0); +} + +void +usage() +{ + + (void)fprintf(stderr, "usage: random [-er] [denominator]\n"); + exit(1); +} |