main.cpp

/*
 * Passthrough judge is ment to be used with data-only-judge-wrapper.
 * It reads the first line of the input file where the expected exit code is,
 * passes the rest of the input file to the output, and yields given exit code.
 * 
 * (C) 2018 ReCodEx Team <github.com/ReCodEx>
 *
 * Usage: recodex-judge-passthrough <file> <file>
 *
 * Enjoy :o)
 */

#include <iostream>
#include <string>
#include <fstream>
#include <stdexcept>
#include <cstdint>

#define	RES_ERROR	2

using namespace std;


/**
 * Class taken from a snippet
 * https://gist.github.com/tomykaira/f0fd86b6c73063283afe550bc5d77594
 */
class Base64 {
public:
	static std::string Encode(const std::string data) {
		static constexpr char sEncodingTable[] = {
			'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
			'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
			'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
			'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
			'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
			'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
			'w', 'x', 'y', 'z', '0', '1', '2', '3',
			'4', '5', '6', '7', '8', '9', '+', '/'
		};

		size_t in_len = data.size();
		size_t out_len = 4 * ((in_len + 2) / 3);
		std::string ret(out_len, '\0');
		size_t i;
		char *p = const_cast<char*>(ret.c_str());

		for (i = 0; i < in_len - 2; i += 3) {
			*p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
			*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
			*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int) (data[i + 2] & 0xC0) >> 6)];
			*p++ = sEncodingTable[data[i + 2] & 0x3F];
		}
		if (i < in_len) {
			*p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
			if (i == (in_len - 1)) {
				*p++ = sEncodingTable[((data[i] & 0x3) << 4)];
				*p++ = '=';
			}
			else {
				*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
				*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2)];
			}
			*p++ = '=';
		}

		return ret;
	}

	static std::string Decode(const std::string& input, std::string& out) {
		static constexpr unsigned char kDecodingTable[] = {
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
			52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
			64,	0,	1,	2,	3,	4,	5,	6,	7,	8,	9, 10, 11, 12, 13, 14,
			15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
			64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
			41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
			64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
		};

		size_t in_len = input.size();
		if (in_len % 4 != 0) return "Input data size is not a multiple of 4";

		size_t out_len = in_len / 4 * 3;
		if (input[in_len - 1] == '=') out_len--;
		if (input[in_len - 2] == '=') out_len--;

		out.resize(out_len);

		for (size_t i = 0, j = 0; i < in_len;) {
			uint32_t a = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
			uint32_t b = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
			uint32_t c = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
			uint32_t d = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];

			uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6);

			if (j < out_len) out[j++] = (triple >> 2 * 8) & 0xFF;
			if (j < out_len) out[j++] = (triple >> 1 * 8) & 0xFF;
			if (j < out_len) out[j++] = (triple >> 0 * 8) & 0xFF;
		}

		return "";
	}

};


/*
 * Application entry point.
 */
int main(int argc, char **argv)
{
	// Check amount of program arguments.
	if (argc != 3) {
		cerr << "Wrong amount of arguments." << endl;
		return RES_ERROR;
	}

	try {
		ifstream inputFile(argv[1]);
		
		// Get the first line which holds the exit code
		std::string line, decoded, result;
		int exitCode = 0;
		if (getline(inputFile, line) && line.size() > 0) {
			exitCode = stoi(line);
			if (exitCode < 0 || exitCode > 255) {
				throw runtime_error("Invalid exit code value.");
			}
		} else {
			throw runtime_error("No exit code value specified.");
		}

		// Get the stdout and decode it
		if (getline(inputFile, line) && line.size() > 0) {
			result = Base64::Decode(line, decoded);
			if (!result.empty()) {
				throw runtime_error(result);
			}
			cout << decoded;
		}

		// Get the stderr and decode it
		if (getline(inputFile, line) && line.size() > 0) {
			result = Base64::Decode(line, decoded);
			if (!result.empty()) {
				throw runtime_error(result);
			}
			cerr << decoded;
		}

		// Copy the rest of the input file to the output...
		inputFile.close();

		return exitCode;
	}
	catch(exception &e) {
		cerr << "Internal Error: " << e.what() << endl;
		return RES_ERROR;
	}
}