//头文件
#define FILEMAP_MAP_SIZE (64 * 1024 * 1024) //每次映射64M
#define FILEMAP_STEP_SIZE (32 * 1024 * 1024) //读大数据的时候每次前移32M
class CFileMap
{
HANDLE m_hFile;
HANDLE m_hMap;
int m_Size; //文件长度,以字节计
BYTE* m_Buf; //文件的内存映射区
int m_FilePosAlign; //映射的文件偏移
bool m_ReadOnly;
public:
CFileMap();
~CFileMap();
bool ReadOpen(const char* fname);
bool WriteOpen(const char* fname, int size, bool is_hidden = false, bool is_sysyem = false);
void Close();
BYTE* GetBuf(int pos);
int GetSize()
{
return m_Size;
}
};
//代码文件
CFileMap::CFileMap()
{
m_FilePosAlign = 0;
m_hFile = 0;
m_hMap = 0;
m_Size = 0;
m_Buf = 0;
}
//析构函数，关闭内存映射
CFileMap::~CFileMap()
{
Close();
}
//只读
bool CFileMap::ReadOpen(const char* fname)
{
m_ReadOnly = true;
m_hFile = CreateFile(fname, GENERIC_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if(m_hFile == INVALID_HANDLE_VALUE)
{
m_hFile = 0;
return false;
}
m_Size = GetFileSize(m_hFile, 0);
if(m_Size == INVALID_FILE_SIZE)
{
CloseHandle(m_hFile);
m_Size = 0;
m_hFile = 0;
return false;
}
m_hMap = CreateFileMapping(m_hFile, 0, PAGE_READONLY, 0, 0, 0);
if(m_hMap == 0)
{
CloseHandle(m_hFile);
m_Size = 0;
m_hFile = 0;
return false;
}
return true;
}
//只写
bool CFileMap::WriteOpen(const char* fname, int size, bool is_hidden, bool is_sysyem)
{
m_ReadOnly = false;
DWORD attr = FILE_ATTRIBUTE_NORMAL;
if(is_hidden)
attr |= FILE_ATTRIBUTE_HIDDEN;
if(is_sysyem)
attr |= FILE_ATTRIBUTE_SYSTEM;
m_hFile = CreateFile(fname, GENERIC_READ|GENERIC_WRITE, 0, 0, CREATE_ALWAYS, attr, 0);
if(m_hFile == INVALID_HANDLE_VALUE)
{
m_hFile = 0;
return false;
}
m_hMap = CreateFileMapping(m_hFile, 0, PAGE_READWRITE, 0, size, 0);
if(m_hMap == 0)
{
CloseHandle(m_hFile);
m_hFile = 0;
return false;
}
m_Size = size;
return true;
}
//关闭文件映射
void CFileMap::Close()
{
if(m_Buf != 0)
UnmapViewOfFile(m_Buf);
if(m_hMap != 0)
CloseHandle(m_hMap);
if(m_hFile != 0)
CloseHandle(m_hFile);
m_hFile = 0;
m_hMap = 0;
m_Size = 0;
m_Buf = 0;
m_FilePosAlign = 0;
}
//获得文件的内存区映射地址
BYTE* CFileMap::GetBuf(int pos)
{
if(pos > m_Size)
return 0;
BYTE* addr; //返回的内存地地址
int map_size; //每次映射多长
DWORD access;
if(m_Buf != 0) //已经映射了
{
UnmapViewOfFile(m_Buf);
m_Buf = 0;
}
m_FilePosAlign = pos / FILEMAP_STEP_SIZE * FILEMAP_STEP_SIZE;
if((m_FilePosAlign + FILEMAP_MAP_SIZE) > m_Size)
map_size = m_Size - m_FilePosAlign;
else
map_size = FILEMAP_MAP_SIZE;
if(m_ReadOnly)
access = FILE_MAP_READ;
else
access = FILE_MAP_ALL_ACCESS;
m_Buf = (BYTE*)MapViewOfFile(m_hMap, access, 0, m_FilePosAlign, map_size);
if(m_Buf == 0)
{
m_FilePosAlign = 0;
return 0;
}
else
{
addr = m_Buf + (pos - m_FilePosAlign);
return addr;
}
} |