99 lines
2.9 KiB
C++
99 lines
2.9 KiB
C++
#include "FileManager.h"
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#include <cstring>
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#include <fstream>
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#include <sstream>
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#include <stdexcept>
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#include <utility>
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namespace NGame {
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TFileManager::TFileManager(const std::string& dataDirectory, const std::string& archivePath, std::size_t cacheSize)
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: DataDirectory_(dataDirectory), ArchivePath_(archivePath), Cache_(cacheSize) {
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}
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std::string TFileManager::Get(const std::string& path) {
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if (Cache_.Contains(path)) {
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return Cache_.Get(path);
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}
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auto getAttempt = FromFilesystem(path);
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if (getAttempt.second) {
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Cache_.Set(path, getAttempt.first);
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return getAttempt.first;
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}
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getAttempt = FromArchive(path);
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if (getAttempt.second) {
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Cache_.Set(path, getAttempt.first);
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return getAttempt.first;
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}
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throw std::runtime_error("can't find file " + path);
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}
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std::pair<std::string, bool> TFileManager::FromFilesystem(const std::string& path) {
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auto finalPath = DataDirectory_ + "/" + path;
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std::ifstream fileStream(finalPath, std::ios::in | std::ios::binary);
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if (!fileStream.is_open()) {
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return std::make_pair<std::string, bool>({}, false);
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}
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std::stringstream fileStringStream;
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fileStringStream << fileStream.rdbuf();
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return std::make_pair(fileStringStream.str(), true);
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}
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std::pair<std::string, bool> TFileManager::FromArchive(const std::string& path) {
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std::ifstream archiveStream(ArchivePath_, std::ios::in | std::ios::binary);
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if (!archiveStream.is_open()) {
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return std::make_pair<std::string, bool>({}, false);
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}
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// Identify and validate PAK file
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char identifier[4];
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archiveStream.read(identifier, 4);
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if (std::memcmp(identifier, "PACK", 4)) {
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return std::make_pair<std::string, bool>({}, false);
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}
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std::uint32_t tocOffset = ReadInt32(archiveStream);
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std::uint32_t tocSize = ReadInt32(archiveStream) / 64;
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if (!tocSize || tocOffset < 12) {
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return std::make_pair<std::string, bool>({}, false);
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}
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// Find requested file
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archiveStream.seekg(tocOffset);
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for (std::uint32_t index = 0; index < tocSize; ++index) {
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char name[56];
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archiveStream.read(name, 56);
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std::uint32_t fileOffset = ReadInt32(archiveStream);
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std::uint32_t fileSize = ReadInt32(archiveStream);
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if (std::strncmp(name, path.c_str(), 56)) {
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continue;
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}
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archiveStream.seekg(fileOffset);
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std::string result(fileSize, 0);
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archiveStream.read(result.data(), result.size());
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return std::make_pair(result, true);
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}
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return std::make_pair<std::string, bool>({}, false);
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}
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std::uint32_t TFileManager::ReadInt32(std::ifstream& stream) {
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unsigned char bytes[4];
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stream.read(reinterpret_cast<char*>(bytes), 4);
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return (bytes[0] << 0) | (bytes[1] << 8) | (bytes[2] << 16) | (bytes[3] << 24);
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}
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} // namespace NGame
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