mtp/MtpStringBuffer.cpp

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright (C) 2014 TeamWin - bigbiff and Dees_Troy mtp database conversion to C++
 */

#include <string.h>
#include "MtpDataPacket.h"
#include "MtpStringBuffer.h"

MtpStringBuffer::MtpStringBuffer()
	:	mCharCount(0),
		mByteCount(1)
{
	mBuffer[0] = 0;
}

MtpStringBuffer::MtpStringBuffer(const char* src)
	:	mCharCount(0),
		mByteCount(1)
{
	set(src);
}

MtpStringBuffer::MtpStringBuffer(const uint16_t* src)
	:	mCharCount(0),
		mByteCount(1)
{
	set(src);
}

MtpStringBuffer::MtpStringBuffer(const MtpStringBuffer& src)
	:   mCharCount(src.mCharCount),
		mByteCount(src.mByteCount)
{
	memcpy(mBuffer, src.mBuffer, mByteCount);
}


MtpStringBuffer::~MtpStringBuffer() {
}

void MtpStringBuffer::set(const char* src) {
	size_t length = strlen(src);
	if (length >= sizeof(mBuffer))
		length = sizeof(mBuffer) - 1;
	memcpy(mBuffer, src, length);

	// count the characters
	int count = 0;
	char ch;
	while ((ch = *src++) != 0) {
		if ((ch & 0x80) == 0) {
			// single byte character
		} else if ((ch & 0xE0) == 0xC0) {
			// two byte character
			if (! *src++) {
				// last character was truncated, so ignore last byte
				length--;
				break;
			}
		} else if ((ch & 0xF0) == 0xE0) {
			// 3 byte char
			if (! *src++) {
				// last character was truncated, so ignore last byte
				length--;
				break;
			}
			if (! *src++) {
				// last character was truncated, so ignore last two bytes
				length -= 2;
				break;
			}
		}
		count++;
	}

	mByteCount = length + 1;
	mBuffer[length] = 0;
	mCharCount = count;
}

void MtpStringBuffer::set(const uint16_t* src) {
	int count = 0;
	uint16_t ch;
	uint8_t* dest = mBuffer;

	while ((ch = *src++) != 0 && count < 255) {
		if (ch >= 0x0800) {
			*dest++ = (uint8_t)(0xE0 | (ch >> 12));
			*dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
			*dest++ = (uint8_t)(0x80 | (ch & 0x3F));
		} else if (ch >= 0x80) {
			*dest++ = (uint8_t)(0xC0 | (ch >> 6));
			*dest++ = (uint8_t)(0x80 | (ch & 0x3F));
		} else {
			*dest++ = ch;
		}
		count++;
	}
	*dest++ = 0;
	mCharCount = count;
	mByteCount = dest - mBuffer;
}

void MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
	int count = packet->getUInt8();
	uint8_t* dest = mBuffer;
	for (int i = 0; i < count; i++) {
		uint16_t ch = packet->getUInt16();
		if (ch >= 0x0800) {
			*dest++ = (uint8_t)(0xE0 | (ch >> 12));
			*dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
			*dest++ = (uint8_t)(0x80 | (ch & 0x3F));
		} else if (ch >= 0x80) {
			*dest++ = (uint8_t)(0xC0 | (ch >> 6));
			*dest++ = (uint8_t)(0x80 | (ch & 0x3F));
		} else {
			*dest++ = ch;
		}
	}
	*dest++ = 0;
	mCharCount = count;
	mByteCount = dest - mBuffer;
}

void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
	int count = mCharCount;
	const uint8_t* src = mBuffer;
	packet->putUInt8(count > 0 ? count + 1 : 0);

	// expand utf8 to 16 bit chars
	for (int i = 0; i < count; i++) {
		uint16_t ch;
		uint16_t ch1 = *src++;
		if ((ch1 & 0x80) == 0) {
			// single byte character
			ch = ch1;
		} else if ((ch1 & 0xE0) == 0xC0) {
			// two byte character
			uint16_t ch2 = *src++;
			ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
		} else {
			// three byte character
			uint16_t ch2 = *src++;
			uint16_t ch3 = *src++;
			ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
		}
		packet->putUInt16(ch);
	}
	// only terminate with zero if string is not empty
	if (count > 0)
		packet->putUInt16(0);
}