love/src/common/b64.cpp

/**
 * Copyright (c) 2006-2022 LOVE Development Team
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 **/

#include "b64.h"
#include "Exception.h"

#include <limits>
#include <stdio.h>

namespace love
{

// Translation table as described in RFC1113
static const char cb64[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

// Translation table to decode (created by Bob Trower)
static const char cd64[]="|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`abcdefghijklmnopq";

/**
 * encode 3 8-bit binary bytes as 4 '6-bit' characters
 **/
static void b64_encode_block(char in[3], char out[4], int len)
{
	out[0] = (char) cb64[(int)((in[0] & 0xfc) >> 2)];
	out[1] = (char) cb64[(int)(((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4))];
	out[2] = (char) (len > 1 ? cb64[(int)(((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6))] : '=');
	out[3] = (char) (len > 2 ? cb64[(int)(in[2] & 0x3f)] : '=');
}

char *b64_encode(const char *src, size_t srclen, size_t linelen, size_t &dstlen)
{
	if (linelen == 0)
		linelen = std::numeric_limits<size_t>::max();

	size_t blocksout = 0;
	size_t srcpos = 0;

	size_t adjustment = (srclen % 3) ? (3 - (srclen % 3)) : 0;
	size_t paddedlen = ((srclen + adjustment) / 3) * 4;

	dstlen = paddedlen + paddedlen / linelen;

	if (dstlen == 0)
		return nullptr;

	char *dst = nullptr;
	try
	{
		dst = new char[dstlen + 1];
	}
	catch (std::exception &)
	{
		throw love::Exception("Out of memory.");
	}

	size_t dstpos = 0;

	while (srcpos < srclen)
	{
		char in[3]  = {0};
		char out[4] = {0};

		int len = 0;

		for (int i = 0; i < 3; i++)
		{
			if (srcpos >= srclen)
				break;

			in[i] = src[srcpos++];
			len++;
		}

		if (len > 0)
		{
			b64_encode_block(in, out, len);

			for (int i = 0; i < 4 && dstpos < dstlen; i++, dstpos++)
				dst[dstpos] = out[i];

			blocksout++;
		}

		if (blocksout >= linelen / 4 || srcpos >= srclen)
		{
			if (blocksout > 0 && dstpos < dstlen)
				dst[dstpos++] = '\n';

			blocksout = 0;
		}
	}

	dst[dstpos] = '\0';
	return dst;
}

static void b64_decode_block(char in[4], char out[3])
{
	out[0] = (char)(in[0] << 2 | in[1] >> 4);
	out[1] = (char)(in[1] << 4 | in[2] >> 2);
	out[2] = (char)(((in[2] << 6) & 0xc0) | in[3]);
}

char *b64_decode(const char *src, size_t srclen, size_t &size)
{
	size_t paddedsize = (srclen / 4) * 3;

	char *dst = nullptr;
	try
	{
		dst = new char[paddedsize];
	}
	catch (std::exception &)
	{
		throw love::Exception("Out of memory.");
	}

	char *d = dst;

	char in[4]  = {0};
	char out[3] = {0};
	size_t i, len, srcpos = 0;

	while (srcpos <= srclen)
	{
		for (len = 0, i = 0; i < 4 && srcpos <= srclen; i++)
		{
			char v = 0;

			while (srcpos <= srclen && v == 0)
			{
				v = src[srcpos++];
				v = (char)((v < 43 || v > 122) ? 0 : cd64[v - 43]);
				if (v != 0)
					v = (char)((v == '$') ? 0 : v - 61);
			}

			if (srcpos <= srclen)
			{
				len++;
				if (v != 0)
					in[i] = (char)(v - 1);
			}
			else
				in[i] = 0;
		}

		if (len)
		{
			b64_decode_block(in, out);
			for (i = 0; i < len - 1; i++)
				 *(d++) = out[i];
		}
	}

	size = (size_t)(ptrdiff_t) (d - dst);
	return dst;
}

} // love