/*
 * rasgen - random ASCII string generator
 */
/*-
 * Copyright (c) 2009-2018
 *	Jeffrey Allen Neitzel <jan (at) etsh (dot) io>.
 *	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.
 *
 * THIS SOFTWARE IS PROVIDED BY JEFFREY ALLEN NEITZEL ``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 JEFFREY ALLEN NEITZEL 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.
 *
 *	@(#)$Id: rasgen.c,v 1.2 2018/09/27 07:53:18 jneitzel Exp $
 */

/*
 * **** Required Header Files ****
 */
#include "config.h"

#ifndef	S_SPLINT_S
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#endif

/*
 * #undef DEBUG for production build
 */
#undef	DEBUG

extern	char	*__progname;

#define	STRANDMAX	95		/* assumes 94 usable characters */
static	int	strand[STRANDMAX];

static	bool	isunique(int, int);

/*
 * NAME
 *	rasgen - random ASCII string generator
 *
 * SYNOPSIS
 *	rasgen length
 *
 * DESCRIPTION
 *	See the rasgen(1) manual page for full details.
 */
int
main(int argc, char **argv)
{
	char *blen;
	long  llen;
	int   i, ilen, n, t;

	/* Check for incorrect usage. */
	if (argc != 2) {
		(void)fprintf(stderr, "usage: %s length\n", __progname);
		return 1;
	}

	/* Get length, and check if it is invalid. */
	errno = 0;
	llen  = strtol(argv[1], &blen, 10);
	if (errno != 0 || *argv[1] == '\0' || (*argv[1] == '0' &&
	    *(argv[1] + 1) >= '0' && *(argv[1] + 1) <= '9') || *blen != '\0' ||
	    llen  <= 0 || llen > (int)(sizeof(strand) / sizeof(int) - 1)) {
		(void)fprintf(stderr, "%s: %s: Invalid length\n",
		      __progname, argv[1]);
		return 1;
	}

#if	HAVE_ARC4RANDOM_UNIFORM == 0
	/*
	 * Delay srandom(3) seeding w/ time(2) by 1 second.  This is so that
	 * doing `rasgen length ; rasgen length ; rasgen length' or similar
	 * doesn't generate 3 identical strings for the specified lengths.
	 */
	(void)sleep(1);

	/* Seed random number generator. */
	srandom((unsigned int)time(NULL));
#endif

	/* Generate string. */
	for (ilen = (int)llen, i = t = 0; i < ilen; t++) {
#if	HAVE_ARC4RANDOM_UNIFORM == 0
		n = (int)(random() & 0177);
#else
		n = (int)arc4random_uniform(0200);
#endif
		if (isprint(n) && n != 040 && isunique(n, i)) {
			strand[i] = n;
			i++;
		}
	}

	/* Print string to standard output. */
	for (i = 0; i < ilen; i++)
		(void)printf("%c", strand[i]);
	(void)printf("\n");
#ifdef	DEBUG
	(void)fprintf(stderr, "total iterations == %d\n", t);
#endif

	return 0;
}

/*
 * Return true if specified num is unique from 0 to specified idx
 * of global strand.  Otherwise, return false if it is not unique.
 */
static bool
isunique(int num, int idx)
{
	int i;

	for (i = 0; i < idx; i++)
		if (strand[i] == num)
			return false;
#ifdef	DEBUG
	(void)fprintf(stderr, "isunique: %c @ %d\n", num, idx);
#endif
	return true;
}