protected virtual void Dispose(bool disposing)
{
if (IsOpen)
{
Win32MapApis.CloseHandle(_hMap);
}
_hMap = NULL_HANDLE;
if (disposing)
{
GC.SuppressFinalize(this);
}
}
Create(string fileName, MapProtection protection,
long maxSize, String name)
{
MemoryMappedFile map = new MemoryMappedFile();
if (!map.Is64bit && maxSize > uint.MaxValue)
{
throw new ConstraintException("32bit systems support max size of 4gb.");
}
// open file first
IntPtr hFile = INVALID_HANDLE_VALUE;
if (!string.IsNullOrEmpty(fileName))
{
if (maxSize == 0)
{
if (!File.Exists(fileName))
{
throw new Exception(string.Format("Winterdom.IO.FileMap.MemoryMappedFile.Create - \"{0}\" does not exist ==> Unable to map entire file", fileName));
}
FileInfo backingFileInfo = new FileInfo(fileName);
maxSize = backingFileInfo.Length;
if (maxSize == 0)
{
throw new Exception(string.Format("Winterdom.IO.FileMap.MemoryMappedFile.Create - \"{0}\" is zero bytes ==> Unable to map entire file", fileName));
}
}
// determine file access needed
// we'll always need generic read access
int desiredAccess = GENERIC_READ;
if ((protection == MapProtection.PageReadWrite) ||
(protection == MapProtection.PageWriteCopy))
{
desiredAccess |= GENERIC_WRITE;
}
// open or create the file
// if it doesn't exist, it gets created
hFile = Win32MapApis.CreateFile(
fileName, desiredAccess, 0,
IntPtr.Zero, OPEN_ALWAYS, 0, IntPtr.Zero
);
if (hFile == INVALID_HANDLE_VALUE)
{
throw new FileMapIOException(Marshal.GetHRForLastWin32Error());
}
map._fileName = fileName;
}
map._hMap = Win32MapApis.CreateFileMapping(
hFile, IntPtr.Zero, (int)protection,
(int)((maxSize >> 32) & 0xFFFFFFFF),
(int)(maxSize & 0xFFFFFFFF), name
);
// close file handle, we don't need it
if (hFile != INVALID_HANDLE_VALUE)
{
Win32MapApis.CloseHandle(hFile);
}
if (map._hMap == NULL_HANDLE)
{
throw new FileMapIOException(Marshal.GetHRForLastWin32Error());
}
map._protection = protection;
map._maxSize = maxSize;
return(map);
}