#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <assert.h>
#include <string.h>

/* rand_passwd.c
 * author: greg hamerly (greg_hamerly at baylor dot edu)
 * 
 * This program chooses a random password for you. Don't like the password it
 * chooses? Run it again. I know, this is a stupidly simple program, but I have
 * found it useful.
 *
 * Copyright (C) 2002  Greg Hamerly (greg_hamerly at baylor dot edu)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * or see http://www.gnu.org/copyleft/gpl.html
 */


/* You can use whatever printable characters you like, but I have reduced the
 * set that is available because international keyboards can make it hard to
 * type passwords which have less-common characters.
 *
 * char *PRINTABLE_CHARS = "`1234567890-=~!@#$%^&*()_+qwertyuiop[]\\QWERTYUIOP{}|asdfghjkl;'ASDFGHJKL:\"zxcvbnm,./ZXCVBNM<>?";
 */
char *PRINTABLE_CHARS = "123456789qwertyuipasdfghjklzxcvbnm";

int main(int argc, char **argv) {
    int numChars, numPrintable;
    int i;

    if (argc != 2) {
        fprintf(stderr, "usage: %s num_chars\n", argv[0]);
        exit(1);
    }

    srand(time(0));

    numChars = atoi(argv[1]); 
    assert(numChars > 0);
    numPrintable = strlen(PRINTABLE_CHARS);

    printf("new password is: ");
    for (i = 0; i < numChars; i++) {
        printf("%c", PRINTABLE_CHARS[rand() % numPrintable]);
    }
    printf("\n");

    return 0;
}