IntPtr _viewBaseAddr = IntPtr.Zero; // Pointer to the base address of the currently mapped view
#endregion Fields
#region Constructors
/// <summary>
/// Constructor used internally by MemoryMappedFile.
/// </summary>
/// <param name="backingFile">Preconstructed MemoryMappedFile</param>
/// <param name="mapSize">Size of the view, in bytes.</param>
/// <param name="isWriteable">True if Read/Write access is desired, False otherwise</param>
internal MapViewStream(MemoryMappedFile backingFile, long mapSize, bool isWriteable)
{
if (backingFile == null)
{
throw new Exception("MapViewStream.MapViewStream - backingFile is null");
}
if (!backingFile.IsOpen)
{
throw new Exception("MapViewStream.MapViewStream - backingFile is not open");
}
if ((mapSize < 1) || (mapSize > backingFile.MaxSize))
{
throw new Exception(string.Format("MapViewStream.MapViewStream - mapSize is invalid. mapSize == {0}, backingFile.MaxSize == {1}", mapSize, backingFile.MaxSize));
}
_backingFile = backingFile;
_isWriteable = isWriteable;
_access = isWriteable ? MapAccess.FileMapWrite : MapAccess.FileMapRead;
// Need a backingFile.SupportsAccess function that takes a MapAccess compares it against its stored MapProtection protection and returns bool
_mapSize = mapSize;
_isOpen = true;
// Map the first view
Seek(0, SeekOrigin.Begin);
}
public static void CreateDotNetProcess32FileMap()
{
DotNetProcess32FileMap = MemoryMappedFile.Create(
MapProtection.PageReadWrite,
FileMapMaxSize,
@"DotNetProcess32FileMap");
}
/// <summary>
/// Open an existing named File Mapping object
/// </summary>
/// <param name="access">desired access to the map</param>
/// <param name="name">name of object</param>
/// <returns>The memory mapped file instance</returns>
public static MemoryMappedFile Open(MapAccess access, String name)
{
MemoryMappedFile map = new MemoryMappedFile
{
_hMap = Win32MapApis.OpenFileMapping((int)access, false, name)
};
if (map._hMap == NULL_HANDLE)
throw new FileMapIOException(Marshal.GetHRForLastWin32Error());
map._maxSize = -1; // debug unknown
return map;
}
/// <summary>
/// Create a named map object
/// </summary>
/// <param name="fileName">name of backing file, or null
/// for a pagefile-backed map</param>
/// <param name="protection">desired access to the mapping
/// object</param>
/// <param name="maxSize">maximum size of filemap object, or 0
/// for size of file</param>
/// <param name="name">name of file mapping object</param>
/// <returns>The memory mapped file instance</returns>
public static MemoryMappedFile 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());
//SafeFileHandle handle = new SafeFileHandle(hFile,true);
//NTFS.Sparse.SparseFile.MarkSparse(handle);
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;
}
