#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#define SIZE (1024*1024)

int main() {
	FILE *in = fopen("source", "r");
	FILE *out = fopen("cracked", "wb");
	char buffer[SIZE];
	size_t bytes;

	while (0 < (bytes = fread(buffer, 1, sizeof(buffer), in)))
		    fwrite(buffer, 1, bytes, out);


	/* 0xe1feff54 */
	unsigned int pattern = 0x54fffee1;
	/* 0x1f2003d5 */
	unsigned int new = 0xd503201f;
	char buf[4];
	fseek(out, 0x520, SEEK_SET);
	while (0 < (bytes = fread(buf, 1, sizeof(buf), out)))
		if (*(unsigned int *)buf == pattern)
			break;
	fwrite(&new, 4, 1, out);

	fclose(in);
	fclose(out);
	return 0;
}