88 lines
1.9 KiB
C++
88 lines
1.9 KiB
C++
#include "libNPK_StdAfx.h"
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#include "libNPK_FileStream.h"
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#include "libNPK_Errors.h"
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#include "libEncrypt_CRC32.h"
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namespace NPK
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{
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CFileStream::CFileStream(CNPKFile* pNPKFile, HANDLE hFile, const FileItemBaseInfo& baseFileInfo)
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: m_pNPKFile(pNPKFile)
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, m_hFileandle(hFile)
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, m_fileName(baseFileInfo.keyName)
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, m_fileOffset(baseFileInfo.fileOffset)
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, m_fileSize(baseFileInfo.fileSize)
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, m_currentOffset(0)
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{
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}
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CFileStream::~CFileStream()
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{
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}
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uint32_t CFileStream::read(void* buffer, uint32_t size)
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{
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if(isEOF())
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{
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return 0; // End of file
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}
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DWORD dwOffset = m_fileOffset + m_currentOffset;
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if (dwOffset != ::SetFilePointer(m_hFileandle, dwOffset, NULL, FILE_BEGIN))
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{
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setLastError(NPK_ERR_FILE_READ, "WinErr=%d", ::GetLastError());
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return 0; // Failed to set file pointer
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}
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DWORD dwRemainBytes = m_fileSize - m_currentOffset;
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DWORD dwToRead = (size < dwRemainBytes) ? size : dwRemainBytes;
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DWORD dwBytesRead = 0;
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if(!::ReadFile(m_hFileandle, buffer, dwToRead, &dwBytesRead, NULL))
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{
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setLastError(NPK_ERR_FILE_READ, "WinErr=%d", ::GetLastError());
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return 0; // Failed to read file
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}
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m_currentOffset += dwBytesRead;
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return dwBytesRead;
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}
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bool CFileStream::seek(uint32_t offset)
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{
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if(offset > m_fileSize)
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{
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setLastError(NPK_ERR_FILE_READ, "Seek offset %u exceeds file size %u", offset, m_fileSize);
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return false; // Seek offset exceeds file size
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}
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m_currentOffset = offset;
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return true;
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}
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uint32_t CFileStream::crc32(void)
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{
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if (m_crc32Calculated) return m_crc32; // CRC32 already calculated
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const size_t kBufferSize = 1024*4;
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uint8_t pTempBuffer[kBufferSize];
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uint32_t currentOffset = m_currentOffset;
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m_currentOffset = 0;
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m_crc32 = 0;
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// Read the entire file to calculate CRC32
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uint32_t bytesRead = 0;
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while ((bytesRead = read(pTempBuffer, kBufferSize)) > 0)
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{
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m_crc32 = crcMemory32(pTempBuffer, bytesRead, m_crc32);
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}
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m_currentOffset = currentOffset;
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m_crc32Calculated = true;
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return m_crc32;
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}
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}
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