protected virtual void Dispose(bool disposing)
{
if (IsOpen)
{
Win32MapApis.CloseHandle(_hMap);
}
_hMap = NULL_HANDLE;
if (disposing)
{
GC.SuppressFinalize(this);
}
}
public static MemoryMappedFile Open(FileMapAccessType access, String name)
{
MemoryMappedFile map = new MemoryMappedFile
{
_hMap = Win32MapApis.OpenFileMapping((int)access, false, name)
};
if (map._hMap == NULL_HANDLE)
{
throw new MMException(Marshal.GetLastWin32Error());
}
map._maxSize = -1;
return(map);
}
public void Flush(IntPtr viewBaseAddr)
{
IntPtr flushLength = new IntPtr(MaxSize);
Win32MapApis.FlushViewOfFile(viewBaseAddr, flushLength);
}
public void UnMapView(IntPtr mapBaseAddr)
{
Win32MapApis.UnmapViewOfFile(mapBaseAddr);
}
public IntPtr MapView(FileMapAccessType access, ref long offset, ref long mapSize)
{
if (!IsOpen)
{
throw new ObjectDisposedException("Memory file already closed");
}
// Grab system info to get the allocation granularity.
SYSTEM_INFO pSI = new SYSTEM_INFO();
Win32MapApis.GetSystemInfo(ref pSI);
// Make sure the offset is aligned.
offset -= offset % pSI.dwAllocationGranularity;
// Find the largest contiguous virtual address space.
MEMORY_BASIC_INFORMATION mbi = new MEMORY_BASIC_INFORMATION();
long address = 0;
const uint MEM_FREE = 0x10000;
long freestart = 0, largestFreestart = 0;
long free = 0, largestFree = 0;
bool recording = false;
while (true)
{
int numBytes = Win32MapApis.VirtualQueryEx(System.Diagnostics.Process.GetCurrentProcess().Handle, (IntPtr)address, out mbi, (uint)Marshal.SizeOf(typeof(MEMORY_BASIC_INFORMATION)));
if (numBytes != Marshal.SizeOf(mbi))
{
break;
}
if (mbi.State == MEM_FREE)
{
if (!recording)
{
freestart = address;
}
free += mbi.RegionSize.ToInt64();
recording = true;
}
else
{
if (recording)
{
if (free > largestFree)
{
largestFree = free;
largestFreestart = freestart;
}
}
free = 0;
recording = false;
}
address += mbi.RegionSize.ToInt64();
}
// Make sure the address is aligned
if (largestFreestart % pSI.dwAllocationGranularity != 0)
{
long diff = pSI.dwAllocationGranularity - (largestFreestart % pSI.dwAllocationGranularity);
largestFreestart += diff;
largestFree -= diff;
}
// Cap map size
if (mapSize > largestFree)
{
mapSize = largestFree;
}
// Edge case
if (offset + mapSize > _fileSize)
{
long diff = offset + mapSize - _fileSize;
if (diff % pSI.dwAllocationGranularity != 0)
{
diff -= diff % pSI.dwAllocationGranularity;
diff += pSI.dwAllocationGranularity;
}
offset -= diff;
}
IntPtr baseAddress = Win32MapApis.MapViewOfFileEx(
_hMap, (int)access,
(int)((offset >> 32) & 0xFFFFFFFF),
(int)(offset & 0xFFFFFFFF),
(IntPtr)mapSize, (IntPtr)largestFreestart);
if (baseAddress == IntPtr.Zero)
{
throw new MMException(Marshal.GetLastWin32Error());
}
return(baseAddress);
}
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 (!File.Exists(fileName))
{
throw new MMException(string.Format("MemoryMappedFile.Create - \"{0}\" does not exist ==> Unable to map file", fileName));
}
FileInfo backingFileInfo = new FileInfo(fileName);
// Get the file size and store it for later use.
map._fileSize = backingFileInfo.Length;
// Set max size if not set. Otherwise cap it.
if (maxSize == 0)
{
maxSize = backingFileInfo.Length;
}
else
{
maxSize = Math.Min(maxSize, backingFileInfo.Length);
}
if (maxSize == 0)
{
throw new MMException(string.Format("Create - \"{0}\" is zero bytes ==> Unable to map file", fileName));
}
int desiredAccess = GENERIC_READ;
int desiredShareMode = FILE_SHARE_READ;
if ((protection == MapProtection.PageReadWrite) ||
(protection == MapProtection.PageWriteCopy))
{
desiredAccess |= GENERIC_WRITE;
desiredShareMode |= FILE_SHARE_WRITE;
}
hFile = Win32MapApis.CreateFile(
fileName, desiredAccess, desiredShareMode,
IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero
);
if (hFile == INVALID_HANDLE_VALUE)
{
throw new MMException(Marshal.GetLastWin32Error());
}
map._fileName = fileName;
}
// Map the file.
map._hMap = Win32MapApis.CreateFileMapping(
hFile, IntPtr.Zero, (int)protection,
(int)((maxSize >> 32) & 0xFFFFFFFF),
(int)(maxSize & 0xFFFFFFFF), name
);
if (hFile != INVALID_HANDLE_VALUE)
{
Win32MapApis.CloseHandle(hFile);
}
if (map._hMap == NULL_HANDLE)
{
throw new MMException(Marshal.GetLastWin32Error());
}
map._protection = protection;
map._maxSize = maxSize;
return(map);
}
