randasc.c

/*
 * randasc.c
 * Generates random ASCII bytes (values 0x20 to 0x7E)
 * Copyright 2012 ctzmsc3
 * License: Do whatever you want.
 */

#include <stdio.h>
#include <stdlib.h>

int
main(int argc, char** argv)
/* first arg is number of chars desired
 * second is number of chars per line before line break
    (defaults to 0, or no breaks)
 * third is randomness source (defaults to /dev/urandom)
 */
{
  FILE* rando;
  int c, n, i;
  unsigned int s=0;
  char* src;
  char a;
  if (argc < 2)
    {
      fprintf(stderr, "Error: not enough args\n");
      return 1;
    }
  n=atoi(argv[1]);
  if (argc >= 3)
    s=atoi(argv[2]);
  if (argc >= 4)
    src=argv[3];
  else
    src="/dev/urandom";
  rando=fopen(src, "r");
  if (rando == NULL)
    {
      fprintf(stderr, "Error: could not open %s\n", src);
      return 1;
    }
  /*do stuff*/
  i=0;
  do
    {
      c=getc(rando);
      if (c == EOF)
        {
          fprintf(stderr, "Error: EOF before finish\n");
          fclose(rando);
          return 1;
        }
      a=c%128; /*eliminate MSB*/
      if (a >= 0x21)
        {
          putchar(a-1); /*eliminate 7f*/
          i++;
          if (s && !(i%s))
            putchar('\n');
        }
    } while (i<n);
  fclose(rando);
  putchar('\n');
  return 0;
}