public unsafe override bool ReadHeader(string filename, FileHeader *header)
{
var path = Path.Combine(_basePath, filename);
if (File.Exists(path) == false)
{
return(false);
}
using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
if (fs.Length != sizeof(FileHeader))
{
return(false); // wrong file size
}
var ptr = (byte *)header;
int remaining = sizeof(FileHeader);
while (remaining > 0)
{
int read;
if (NativeFileMethods.ReadFile(fs.SafeFileHandle, ptr, remaining, out read, null) == false)
{
throw new Win32Exception();
}
if (read == 0)
{
return(false); // we should be reading _something_ here, if we can't, then it is an error and we assume corruption
}
ptr += read;
remaining -= read;
}
return(true);
}
}
public unsafe override bool ReadHeader(string filename, FileHeader *header)
{
var path = Path.Combine(_basePath, filename);
if (File.Exists(path) == false)
{
return(false);
}
using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
var ptr = (byte *)header;
int remaining = sizeof(FileHeader);
while (remaining > 0)
{
int read;
if (NativeFileMethods.ReadFile(fs.SafeFileHandle, ptr, remaining, out read, null) == false)
{
throw new Win32Exception();
}
ptr += read;
remaining -= read;
}
return(true);
}
}
public bool Read(long pageNumber, byte *buffer, int count)
{
if (_readHandle == null)
{
_readHandle = NativeFileMethods.CreateFile(_filename,
NativeFileAccess.GenericRead,
NativeFileShare.Write | NativeFileShare.Read | NativeFileShare.Delete,
IntPtr.Zero,
NativeFileCreationDisposition.OpenExisting,
NativeFileAttributes.Normal,
IntPtr.Zero);
}
long position = pageNumber * AbstractPager.PageSize;
var overlapped = new Overlapped((int)(position & 0xffffffff), (int)(position >> 32), IntPtr.Zero, null);
NativeOverlapped *nativeOverlapped = overlapped.Pack(null, null);
try
{
while (count > 0)
{
int read;
if (NativeFileMethods.ReadFile(_readHandle, buffer, count, out read, nativeOverlapped) == false)
{
int lastWin32Error = Marshal.GetLastWin32Error();
if (lastWin32Error == ErrorHandleEof)
{
return(false);
}
throw new Win32Exception(lastWin32Error);
}
count -= read;
buffer += read;
}
return(true);
}
finally
{
Overlapped.Free(nativeOverlapped);
}
}