xor.c

/*
 * xor filter -- 2017 Neale Pickett <zephyr@dirtbags.net>
 *
 * This file is in the public domain.  I make no promises about the functionality
 * of this program. 
 */

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

int
main(int argc, char *argv[])
{
	int start = 1;
	int base = 0;
	int arg;

	if (argv[start] && (0 == strcmp(argv[start], "-x"))) {
		base = 16;
		start += 1;
	}

	if (start + 1 > argc) {
		fprintf(stderr, "Usage: %s [-x] m1 [m2 ...]\n", argv[0]);
		return 1;
	}

	arg = start;

	while (1) {
		int c = getchar();
		unsigned char mask;

		if (!argv[arg]) {
			arg = start;
		}
		mask = strtol(argv[arg++], NULL, base);

		if (EOF == c) {
			break;
		}

		c ^= mask;
		putchar(c);
	}

	return 0;
}