text: /*	$NetBSD: shuffle.c,v 1.21 2011/09/16 15:39:29 joerg Exp $	*/
  
  /*
   * Copyright (c) 1998
   * 	Perry E. Metzger.  All rights reserved.
   *
   * 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 acknowledgment:
   *	This product includes software developed for the NetBSD Project
   *	by Perry E. Metzger.
   * 4. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
   */
  
  #include <sys/cdefs.h>
  #ifndef lint
  __RCSID("$NetBSD: shuffle.c,v 1.21 2011/09/16 15:39:29 joerg Exp $");
  #endif /* not lint */
  
  #include <sys/time.h>
  
  #include <err.h>
  #include <errno.h>
  #include <limits.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <util.h>
  
  static size_t *get_shuffle(size_t);
  __dead static void usage(void);
  static void get_lines(const char *, char ***, size_t *);
  static size_t get_number(const char *, int);
  
  /*
   * get_shuffle --
   *	Construct a random shuffle array of t elements
   */
  static size_t *
  get_shuffle(size_t t)
  {
  	size_t *shuffle;
  	size_t i, j, k, temp;
  	
  	shuffle = emalloc(t * sizeof(size_t));
  
  	for (i = 0; i < t; i++)
  		shuffle[i] = i;
  	
  	/*
  	 * This algorithm taken from Knuth, Seminumerical Algorithms,
  	 * 2nd Ed., page 139.
  	 */
  
  	for (j = t - 1; j > 0; j--) {
  		k = arc4random() % (j + 1);
  		temp = shuffle[j];
  		shuffle[j] = shuffle[k];
  		shuffle[k] = temp;
  	}
  
  	return shuffle;
  }
  
  /*
   * usage --
   *	Print a usage message and exit
   */
  static void
  usage(void)
  {
  
  	(void) fprintf(stderr,
      "usage: %s [-0] [-f <filename>] [-n <number>] [-p <number>] [<arg> ...]\n",
  		getprogname());
  	exit(1);
  }
  
  
  /*
   * get_lines --
   *	Return an array of lines read from input
   */
  static void
  get_lines(const char *fname, char ***linesp, size_t *nlinesp)
  {
  	FILE *fp;
  	char *line;
  	size_t size, nlines = 0, maxlines = 128;
  	char **lines = emalloc(sizeof(char *) * maxlines);
  
  	if (strcmp(fname, "-") == 0)
  		fp = stdin;
  	else
  		if ((fp = fopen(fname, "r")) == NULL)
  			err(1, "Cannot open `%s'", fname);
  
  	while ((line = fgetln(fp, &size)) != NULL) {
  		if (size > 0 && line[size - 1] == '\n')
  			size--;
  		lines[nlines] = emalloc(size + 1);
  		(void)memcpy(lines[nlines], line, size);
  		lines[nlines++][size] = '\0';
  		if (nlines >= maxlines) {
  			maxlines *= 2;
  			lines = erealloc(lines, (sizeof(char *) * maxlines));
  		}
  	}
  	lines[nlines] = NULL;
  
  	*linesp = lines;
  	*nlinesp = nlines;
  	if (strcmp(fname, "-") != 0)
  		(void)fclose(fp);
  }
  
  /*
   * get_number --
   *	Return a number or exit on error
   */
  static size_t
  get_number(const char *str, int ch)
  {
  	char *estr;
  	long number;
  
  	errno = 0;
  	number = strtol(str, &estr, 0);
  	if ((number == LONG_MIN || number == LONG_MAX) && errno == ERANGE)
  		err(1, "bad -%c argument `%s'", ch, str);
  	if (*estr)
  		errx(1, "non numeric -%c argument `%s'", ch, str);
  	if (number < 0)
  		errx(1, "negative -%c argument `%s'", ch, str);
  	return (size_t) number;
  }
  
  int
  main(int argc, char *argv[])
  {
  	int nflag = 0, pflag = 0, ch;
  	char *fname = NULL;
  	size_t *shuffle = NULL;
  	char **lines = NULL;
  	size_t nlines = 0, pick = 0, i;
  	char sep = '\n';
  	
  	while ((ch = getopt(argc, argv, "0f:n:p:")) != -1) {
  		switch(ch) {
  		case '0':
  			sep = '\0';
  			break;
  		case 'f':
  			fname = optarg;
  			break;
  		case 'n':
  			nlines = get_number(optarg, ch);
  			nflag = 1;
  			break;
  		case 'p':
  			pick = get_number(optarg, ch);
  			pflag = 1;
  			break;
  		case '?':
  		default:
  			usage();
  		}
  	}
  	argc -= optind;
  	argv += optind;
  
  	if ((fname && nflag) || (nflag && (argc > 0)))
  		usage();
  
  	if (fname != NULL)
  		get_lines(fname, &lines, &nlines);
  	else if (nflag == 0) {
  		lines = argv;
  		nlines = argc;
  	}
  
  	if (nlines > 0)
  		shuffle = get_shuffle(nlines);
  
  	if (pflag) {
  		if (pick > nlines)
  			errx(1, "-p specified more components than exist.");
  		nlines = pick;
  	}
  
  	for (i = 0; i < nlines; i++) {
  		if (nflag)
  			printf("%ld", (long)shuffle[i]);
  		else
  			printf("%s", lines[shuffle[i]]);
  		putc(sep, stdout);
  	}
  
  	return 0;
  }
  