//
// reverse <input filename> <output filename>
//
// dumb program to reverse the bytes in a file; for a lame
// layer of obfuscation or something like that
//

#include <stdio.h>

const int BLOCK_SIZE = 4096;

int main(int argc, char* argv[])
{
	if (argc < 3)
	{
		printf("Usage: %s <infile> <outfile>\n");
		return 1;
	}

	FILE* infp = fopen(argv[1], "rb");
	if (infp == 0)
	{
		fprintf(stderr, "Unable to open \"%s\"\n", argv[1]);
		return 1;
	}

	FILE* outfp = fopen(argv[2], "wb");
	if (outfp == 0)
	{
		fclose(infp);

		fprintf(stderr, "Unable to open \"%s\"\n", argv[2]);
		return 1;
	}

	while (!feof(infp))
	{
		char block[BLOCK_SIZE];
		char revblock[BLOCK_SIZE];
		size_t i, j;

		size_t numread = fread(block, 1, BLOCK_SIZE, infp);

		for (i = 0; i < numread; i++)
			revblock[numread - i - 1] = block[i];

		if (fwrite(revblock, numread, 1, outfp) != numread)
		{
			fprintf(stderr, "Error writing to output file\n");
			break;
		}
	}
	
	fclose(infp);
	fclose(outfp);

	return 0;
}