mtgodot-poc/extension/src/platform/EterBase/MappedFile.cpp

// Platform implementation of EterBase/MappedFile.h (40250 EterBase/MappedFile.cpp). Everything but Map/Unmap
// is the 40250 code; the view is a POSIX mmap (CreateFileMapping/MapViewOfFile on Windows) of the CFileBase
// stream, aligned down to the allocation granularity exactly as 40250 does.
#include "EterBase/StdAfx.h"
#include "EterBase/MappedFile.h"
#include "EterBase/Debug.h"

#include <cstdio>

#if defined(_WIN32)
#include <io.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#endif

static DWORD allocation_granularity()
{
#if defined(_WIN32)
	SYSTEM_INFO SysInfo;
	GetSystemInfo(&SysInfo);
	return SysInfo.dwAllocationGranularity;
#else
	return static_cast<DWORD>(sysconf(_SC_PAGESIZE));
#endif
}

CMappedFile::CMappedFile() :
m_hFM(NULL),
m_lpMapData(NULL),
m_dataOffset(0),
m_mapSize(0),
m_seekPosition(0),
m_pLZObj(NULL),
m_pbBufLinkData(NULL),
m_dwBufLinkSize(0),
m_pbAppendResultDataBlock(NULL),
m_dwAppendResultDataSize(0)
{
}

CMappedFile::~CMappedFile()
{
	Destroy();
}

BOOL CMappedFile::Create(const char * filename)
{
	Destroy();
	return CFileBase::Create(filename, FILEMODE_READ);
}

BOOL CMappedFile::Create(const char * filename, const void** dest, int offset, int size)
{
	if (!CMappedFile::Create(filename))
		return FALSE;

	int ret = Map(dest, offset, size);
	return (ret) > 0;
}

LPCVOID CMappedFile::Get()
{
	return m_lpData;
}

void CMappedFile::Link(DWORD dwBufSize, const void* c_pvBufData)
{
	m_dwBufLinkSize=dwBufSize;
	m_pbBufLinkData=(BYTE*)c_pvBufData;
}

void CMappedFile::BindLZObject(CLZObject * pLZObj)
{
	assert(m_pLZObj == NULL);
	m_pLZObj = pLZObj;

	Link(m_pLZObj->GetSize(), m_pLZObj->GetBuffer());
}

void CMappedFile::BindLZObjectWithBufferedSize(CLZObject * pLZObj)
{
	assert(m_pLZObj == NULL);
	m_pLZObj = pLZObj;

	Link(m_pLZObj->GetBufferSize(), m_pLZObj->GetBuffer());
}

BYTE* CMappedFile::AppendDataBlock( const void* pBlock, DWORD dwBlockSize )
{
	if( m_pbAppendResultDataBlock )
	{
		delete []m_pbAppendResultDataBlock;
	}

	//realloc
	m_dwAppendResultDataSize  = m_dwBufLinkSize+dwBlockSize;
	m_pbAppendResultDataBlock = new BYTE[m_dwAppendResultDataSize];

	memcpy(m_pbAppendResultDataBlock, m_pbBufLinkData, m_dwBufLinkSize );
	memcpy(m_pbAppendResultDataBlock + m_dwBufLinkSize, pBlock, dwBlockSize );

	//redirect
	Link(m_dwAppendResultDataSize, m_pbAppendResultDataBlock);

	return m_pbAppendResultDataBlock;
}

void CMappedFile::Destroy()
{
	if (m_pLZObj)
	{
		delete m_pLZObj;
		m_pLZObj = NULL;
	}

	if (NULL != m_lpMapData)
	{
		Unmap(m_lpMapData);
		m_lpMapData = NULL;
	}

#if defined(_WIN32)
	if (NULL != m_hFM)
	{
		CloseHandle(m_hFM);
		m_hFM = NULL;
	}
#endif

	if( m_pbAppendResultDataBlock )
	{
		delete []m_pbAppendResultDataBlock;
		m_pbAppendResultDataBlock = NULL;
	}

	m_dwAppendResultDataSize = 0;

	m_pbBufLinkData = NULL;
	m_dwBufLinkSize = 0;

	m_seekPosition = 0;
	m_dataOffset = 0;
	m_mapSize = 0;

	CFileBase::Destroy();
}

int CMappedFile::Seek(DWORD offset, int iSeekType)
{
	switch (iSeekType)
	{
		case SEEK_TYPE_BEGIN:
			if (offset > m_dwSize)
				offset = m_dwSize;

			m_seekPosition = offset;
			break;

		case SEEK_TYPE_CURRENT:
			m_seekPosition = min(m_seekPosition + offset, Size());
			break;

		case SEEK_TYPE_END:
			m_seekPosition = max(0, Size() - offset);
			break;
	}

	return m_seekPosition;
}

int CMappedFile::Map(const void **dest, int offset, int size)
{
	m_dataOffset = offset;

	if (size == 0)
		m_mapSize = m_dwSize;
	else
		m_mapSize = size;

	if (m_dataOffset + m_mapSize > m_dwSize)
		return 0;

	DWORD dwSysGran = allocation_granularity();
	DWORD dwFileMapStart = (m_dataOffset / dwSysGran) * dwSysGran;
	DWORD dwMapViewSize = (m_dataOffset % dwSysGran) + m_mapSize;
	INT iViewDelta = m_dataOffset - dwFileMapStart;

	FILE* fp = static_cast<FILE*>(m_hFile);
#if defined(_WIN32)
	m_hFM = CreateFileMapping((HANDLE) _get_osfhandle(_fileno(fp)), NULL, PAGE_READONLY, 0,
							  m_dataOffset + m_mapSize, NULL);
	if (!m_hFM)
	{
		OutputDebugString("CMappedFile::Map !m_hFM\n");
		return 0;
	}

	m_lpMapData = MapViewOfFile(m_hFM, FILE_MAP_READ, 0, dwFileMapStart, dwMapViewSize);
	if (!m_lpMapData)
	{
		TraceError("CMappedFile::Map !m_lpMapData %lu", GetLastError());
		return 0;
	}
#else
	// A zero-length view (empty file) is a valid 40250 map; mmap rejects length 0.
	if (dwMapViewSize == 0)
		dwMapViewSize = 1;
	void* p = mmap(NULL, dwMapViewSize, PROT_READ, MAP_PRIVATE, fileno(fp), static_cast<off_t>(dwFileMapStart));
	if (p == MAP_FAILED)
	{
		TraceError("CMappedFile::Map !m_lpMapData %s", GetFileName());
		return 0;
	}
	m_lpMapData = p;
#endif

	m_lpData = (char*) m_lpMapData + iViewDelta;
	*dest = (char*) m_lpData;
	m_seekPosition = 0;

	Link(m_mapSize, m_lpData);

	return (m_mapSize);
}

BYTE * CMappedFile::GetCurrentSeekPoint()
{
	return m_pbBufLinkData+m_seekPosition;
}

DWORD CMappedFile::Size()
{
	return m_dwBufLinkSize;
}

DWORD CMappedFile::GetPosition()
{
	return m_dataOffset;
}

BOOL CMappedFile::Read(void * dest, int bytes)
{
	if (m_seekPosition + bytes > Size())
		return FALSE;

	memcpy(dest, GetCurrentSeekPoint(), bytes);
	m_seekPosition += bytes;
	return TRUE;
}

DWORD CMappedFile::GetSeekPosition(void)
{
	return m_seekPosition;
}

void CMappedFile::Unmap(LPCVOID data)
{
#if defined(_WIN32)
	if (!UnmapViewOfFile(data))
		TraceError("CMappedFile::Unmap - Error");
#else
	// Same view length Map computed from the (unchanged) offset and size.
	const DWORD dwSysGran = allocation_granularity();
	DWORD dwMapViewSize = (m_dataOffset % dwSysGran) + m_mapSize;
	if (dwMapViewSize == 0)
		dwMapViewSize = 1;
	if (munmap(const_cast<void*>(data), dwMapViewSize) != 0)
		TraceError("CMappedFile::Unmap - Error");
#endif
	m_lpData = NULL;
}