/// <summary>Read some number of sectors.</summary>
/// <param name="into">Pre-allocated buffer.</param>
/// <param name="logicalSectorId">Logical identifier of the first sector to be read.</param>
/// <param name="sectorsCount">Number of sectors to read.</param>
/// <returns>Buffer address.</returns>
internal unsafe IPartitionClusterData ReadSectors(IPartitionClusterData into, long atOffset,
ulong logicalSectorId, uint sectorsCount = 1)
{
uint bytesPerSector = PartitionManager.Singleton.Geometry.BytesPerSector;
uint expectedCount = sectorsCount * bytesPerSector;
if (null == into)
{
throw new ArgumentNullException();
}
if (0 > atOffset)
{
throw new ArgumentException();
}
if ((into.DataSize - atOffset) < expectedCount)
{
throw new ArgumentException();
}
if (FeaturesContext.DataPoolChecksEnabled)
{
if (expectedCount > into.DataSize)
{
throw new ApplicationException();
}
}
ulong offset = (logicalSectorId + StartSector) * bytesPerSector;
uint totalBytesRead = 0;
// Prevent concurrent reads on this partition.
lock (_ioLock) {
if (!Natives.SetFilePointerEx(_handle, (long)offset, out offset, Natives.FILE_BEGIN))
{
int error = Marshal.GetLastWin32Error();
throw new ApplicationException();
}
uint chainItemsCount = into.GetChainItemsCount();
uint chainLength = into.GetChainLength();
if (chainLength < expectedCount)
{
throw new ApplicationException();
}
uint remainingExpectation = expectedCount;
for (IPartitionClusterData currentData = into; null != currentData; currentData = currentData.NextInChain)
{
uint readSize = remainingExpectation;
if (readSize > into.DataSize)
{
readSize = into.DataSize;
}
uint effectiveReadSize;
if (!Natives.ReadFile(_handle, into.Data + atOffset, readSize, out effectiveReadSize, IntPtr.Zero))
{
int error = Marshal.GetLastWin32Error();
throw new ApplicationException();
}
atOffset += effectiveReadSize;
totalBytesRead += effectiveReadSize;
remainingExpectation -= effectiveReadSize;
}
}
if (totalBytesRead != expectedCount)
{
throw new ApplicationException();
}
return(into);
}
