MyZip/main.cpp

#include <cstdio>
#include <iostream>
#include <fstream>

#include "ZipDefine.h"
#include "CRC.h"

#define TARGET_FILE_NAME "MyZip.txt"

bool ZipArchiver();
uint32_t getCRC32(const uint8_t* pData, size_t length);

int main()
{
	std::printf("==================== Hello Zip! ====================\r\n");
	int iRet = 0;

	// Zip Format define check
	size_t iSizeTest = sizeof(LocalFileHeader);
	if (LOCAL_FILE_HEADER_BYTE != iSizeTest)
	{
		std::printf("1 Wrong Header Size : %zu / %d \r\n", iSizeTest, LOCAL_FILE_HEADER_BYTE);
		iRet = -1;
	}
	iSizeTest = sizeof(CentralDirectory);
	if (CENTRAL_DIRECTORY_BYTE != iSizeTest)
	{
		std::printf("2 Wrong Header Size : %zu / %d \r\n", iSizeTest, CENTRAL_DIRECTORY_BYTE);
		iRet = -1;
	}
	iSizeTest = sizeof(EoCDRecord);
	if (EOCD_BYTE != iSizeTest)
	{
		std::printf("3 Wrong Header Size : %zu / %d \r\n", iSizeTest, EOCD_BYTE);
		iRet = -1;
	}

	// Main Zip archive method
	if (iRet != -1)
	{
		if(!ZipArchiver())
		{
			iRet = -1;
		}
	}

	return iRet;
}

bool ZipArchiver()
{
	LocalFileHeader LFHeader = {};
	CentralDirectory CentDir = {};
	EoCDRecord EOCDR = {};

	using namespace std;

	ifstream fileIn(TARGET_FILE_NAME, ios::binary);
	bool iRet = fileIn.is_open();
	if (!iRet)
	{
		printf("File open failed");
	}
	else
	{
		// 파일 크기 계산
		// seekg(offset, 목표점)
		fileIn.seekg(0, ios::end);
		streamsize fileInSize = fileIn.tellg();
		// beg == begin
		fileIn.seekg(0, ios::beg);

		// TODO : Buffering 으로 구현. 현재는 파일 통짜로 읽음.
		// 메모리 할당
		uint8_t* pFile = (uint8_t *)malloc(fileInSize);

		// Read
		fileIn.read((char *)pFile, fileInSize);

		// ZIP 포맷 채워넣기
		{
			// Get CRC value
			// TODO : streamsize 와 size_t 의 mismatch (long long <-> unsigned long long)
			uint32_t myCRC = getCRC32(pFile, fileInSize);

			// Put PK Signature
			LFHeader.signature = PK_SIGNATURE_LF_HEADER;
			CentDir.signature = PK_SIGNATURE_CENT_DIR;
			EOCDR.signature = PK_SIGNATURE_EO_CDR;
			
			// TOOD : versionMadeBy (Only CentDir)
			// TODO : versionNeededToExtract
			// TODO : generalBitFlag

			// Put compressed method (uncompressed)
			LFHeader.compressionMethod = METHOD_UNCOMPRESSED;
			CentDir.compressionMethod = METHOD_UNCOMPRESSED;
			
			// TODO : lastMode[Time|Date]

			// Put CRC value
			LFHeader.crc32 = myCRC;
			CentDir.crc32 = myCRC;

			// Put File size
			LFHeader.sizeOfUncompressed = (uint32_t)fileInSize;
			CentDir.sizeOfUncompressed = (uint32_t)fileInSize;
			LFHeader.sizeOfCompressed = LFHeader.sizeOfUncompressed;
			CentDir.sizeOfCompressed = CentDir.sizeOfUncompressed;

			// Put File name length
			uint16_t fileNameLeng = strlen(TARGET_FILE_NAME);
			LFHeader.lengthOfFileName = fileNameLeng;
			CentDir.lengthOfFileName = fileNameLeng;

			// Extra Field 는 사용하지 않음
			// LFHeader.lengthOfExtraField = NOT_USED;
			// CentDir.lengthOfExtraField = NOT_USED;

			// TODO : CentDir 나머지 format
			//			- lengthOfFileComment
			//			- diskNumStart;
			//			- attributeInternal;
			//			- attributeExternal;
			//			- offsetLocalHeader;

			// TODO : EOCDR 나머지 format
			//			- diskNumber
			//			- diskNumber_CentralDirStart
			//			- numOfCentralDir
			//			- numOfEntries;
			//			- SizeOfCentralDir;
			//			- OffsetOfCentralDirOffset;
			//			- LengthOfCommentLength;
		}

		// Free
		free(pFile);
	}

	return iRet;
}

uint32_t getCRC32(const uint8_t* pData, size_t length)
{
	uint32_t crc = 0xFFFFFFFF;
	
	// 1. 입력
	for (size_t i = 0; i < length ; i++)
	{
		// Index 추출
		// 입력과 현재 CRC를 1 Byte 씩 XOR + (1의 보수처리)
		uint8_t iTableIdx = (crc ^ pData[i]) & 0xFF;

		// 1 Byte Shift
		crc = crc >> 8;

		// Table 과 XOR 계산
		crc = crc ^ crcTable[iTableIdx];
	}

	// TODO : CRC 최적화
	//		  "_mm_crc32_u16" => MSVC 자체적으로 지원하는 최적화된 CRC 가 있는듯?

	// 1의 보수처리
	return crc ^ 0xFFFFFFFF;
}