androidmanifesteditor/ResStringPool.cpp

/*
 * Copyright (C) 2018 Hein-Pieter van Braam
 *
 * 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.
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include "ResStringPool.h"

char* to_char_string(const char* data, uint32_t length) {
	char* string = (char*) calloc(length + 1, 1);
	for (int i = 0; i < length; ++i) {
		string[i] = *(data + (i * 2));
	}

	return string;
}

void to_wide_string(const char* string, uint16_t* dest) {
	uint32_t len = strlen(string);

	for (int i = 0; i < len; ++i) {
		dest[i] = string[i];
	}

	dest[len] = 0;
}

ResStringPool::ResStringPool() :
		_size(0), _strings(nullptr) {
}

ResStringPool::ResStringPool(const char* data) {
	ResStringPool_header header;
	uint32_t* entries;
	memcpy(&header, data, sizeof(ResStringPool_header));

	if (header.header.type != RES_STRING_POOL_TYPE) {
		printf("Not a ResStringPool!\n");
		return;
	}

    printf("ResStringPool stringCount: %i\n", header.stringCount);
    printf("ResStringPool styleCount: %i\n", header.styleCount);
    printf("ResStringPool stringsStart: %i\n", header.stringsStart);
    printf("ResStringPool flags: 0x%08X\n", header.flags);

	_size = header.stringCount;
	entries = (uint32_t*) (data + header.header.headerSize);
	_strings = (const char**)malloc(_size * sizeof(const char*));

	const char *stringdata = data + header.stringsStart;

	for (int i = 0; i < _size; ++i) {
		uint32_t offset = entries[i];
		size_t size = *((const uint16_t*)(stringdata + offset));

		if ((size & 0x8000) != 0) {
			offset += 2;
			size = ((size & 0x7FFF) << 16) | *((const uint16_t*)(stringdata + offset));
		}
		offset += 2;

		_strings[i] = to_char_string(stringdata + offset, size);
	}
}

const char* ResStringPool::get(int32_t index) const {
	if (index < 0 || index >= _size) {
		return nullptr;
	}

	return _strings[index];
}

ResStringPool_ref ResStringPool::put(const char* string) {
	ResStringPool_ref ref;
	if (! string) {
		printf("Empty string request\n");
		ref.index = -1;
		return ref;
	}

	for (int i = 0; i < _size; ++i) {
		if (strcmp(string, _strings[i]) == 0) {
			printf("Found string '%s' already returning %i\n", string, i);
			ref.index = i;
			return ref;
		}
	}

	++_size;
	_strings = (const char **)realloc(_strings, _size * sizeof(const char**));
	_strings[_size - 1] = strdup(string);

	ref.index = _size - 1;
	printf("Adding new string : '%s' as %i\n", string, ref.index);
	return ref;
}

// TODO why is this necessary?
void ResStringPool::put_empty() {
	printf("Putting empty string at %i\n", _size);
	++_size;
	_strings = (const char **)realloc(_strings, _size * sizeof(const char**));
	_strings[_size - 1] = strdup(""	);
}

uint32_t ResStringPool::serialize(char** data) {
	uint32_t datasize = sizeof(ResStringPool_header) + _size * sizeof(uint32_t);
	*data = (char*)malloc(datasize);

	uint32_t stringloc = 0;
	uint32_t stringsStart = datasize;

	for (int i = 0; i < _size; ++i) {
		uint32_t stringlen = strlen(_strings[i]);
		datasize += (stringlen * 2) + 4;
		*data = (char*)realloc(*data, datasize);

		uint16_t* stringdata = (uint16_t*)((char*)*data + stringsStart + stringloc);

		// TODO: Deal with longer strings, see the parser in the data constructor
		*stringdata = stringlen;
		to_wide_string(_strings[i], stringdata + 1);

		uint32_t* entries = (uint32_t*)((char*)*data + sizeof(ResStringPool_header));
		entries[i] = stringloc;
		stringloc += (stringlen * 2) + 4;
	}

	datasize = datasize + (datasize % 4);
	*data = (char*)realloc(*data, datasize);

	ResStringPool_header* header = (ResStringPool_header*)*data;

	header->stringCount = _size;
	header->stringsStart = stringsStart;
	header->flags = 0;
	header->styleCount = 0;
	header->stylesStart = 0;
	header->header.headerSize = sizeof(ResStringPool_header);
	header->header.type = RES_STRING_POOL_TYPE;
	header->header.size = datasize;

	return datasize;
}

void ResStringPool::dump() {
	for (int i = 0; i < _size; ++i) {
		printf("String %i: '%s'\n", i, _strings[i]);
	}
}

ResStringPool::~ResStringPool() {
	for (int i = 0; i < _size; ++i) {
		free((void*)_strings[i]);
	}
	free(_strings);
}