private void ReadMetadata(VHDX_REGION_TABLE_ENTRY metadataRegion, out VHDX_FILE_PARAMETERS outFileParams, out Int64 outVirtualDiskSize, out uint outLogicalSectorSize)
{
if (metadataRegion.Length < METADATA_TABLE_SIZE)
{
throw new Exception("Metadata region is too small to contain metadata table!");
}
var metadataBytes = mHdd.ReadBytes(checked ((long)metadataRegion.FileOffset), checked ((int)metadataRegion.Length));
var metadataHeader = Program.ToStruct <VHDX_METADATA_TABLE_HEADER>(metadataBytes, 0);
if (metadataHeader.Signature != METADATA_TABLE_SIG)
{
throw new Exception("Bad metadata header sig.");
}
if (metadataHeader.EntryCount > MAX_TABLE_ENTRIES)
{
throw new Exception("Too many metadata entries.");
}
VHDX_FILE_PARAMETERS?fileParams = null;
UInt64?virtualDiskSize = null;
UInt32?logicalSectorSize = null;
for (int i = 0; i < metadataHeader.EntryCount; i++)
{
int readOffset = Program.SizeOf <VHDX_METADATA_TABLE_HEADER>()
+ i * Program.SizeOf <VHDX_METADATA_TABLE_ENTRY>();
var entry = Program.ToStruct <VHDX_METADATA_TABLE_ENTRY>(metadataBytes, readOffset);
if (entry.IsUser)
{
if (entry.IsRequired)
{
throw new Exception($"Unknown required metadata item: {entry.ItemId}");
}
else
{
continue;
}
}
else if (entry.IsRequired && !sKnownMetadataItems.Contains(entry.ItemId))
{
throw new Exception($"Unknown required metadata item: {entry.ItemId}");
}
//the ArraySegment overload of ToStruct will make sure the entry size matches the data item
var entryBytes = new ArraySegment <byte>(metadataBytes, checked ((int)entry.Offset), checked ((int)entry.Length));
if (entry.ItemId == METADATA_FILE_PARAMS)
{
fileParams = Program.ToStruct <VHDX_FILE_PARAMETERS>(entryBytes);
}
else if (entry.ItemId == METADATA_VIRTUAL_DISK_SIZE)
{
virtualDiskSize = Program.ToStruct <UInt64>(entryBytes);
}
else if (entry.ItemId == METADATA_LOGICAL_SECTOR_SIZE)
{
logicalSectorSize = Program.ToStruct <UInt32>(entryBytes);
}
}
if (!fileParams.HasValue || !virtualDiskSize.HasValue || !logicalSectorSize.HasValue)
{
throw new Exception("Missing required metadata!");
}
outFileParams = fileParams.Value;
outVirtualDiskSize = checked ((long)virtualDiskSize.Value);
outLogicalSectorSize = logicalSectorSize.Value;
}
private void ReadMetadata(VHDX_REGION_TABLE_ENTRY metadataRegion, out VHDX_FILE_PARAMETERS outFileParams, out Int64 outVirtualDiskSize, out uint outLogicalSectorSize)
{
if (metadataRegion.Length < METADATA_TABLE_SIZE)
throw new Exception("Metadata region is too small to contain metadata table!");
var metadataBytes = mHdd.ReadBytes(checked((long)metadataRegion.FileOffset), checked((int)metadataRegion.Length));
var metadataHeader = Program.ToStruct<VHDX_METADATA_TABLE_HEADER>(metadataBytes, 0);
if (metadataHeader.Signature != METADATA_TABLE_SIG)
throw new Exception("Bad metadata header sig.");
if (metadataHeader.EntryCount > MAX_TABLE_ENTRIES)
throw new Exception("Too many metadata entries.");
VHDX_FILE_PARAMETERS? fileParams = null;
UInt64? virtualDiskSize = null;
UInt32? logicalSectorSize = null;
for (int i = 0; i < metadataHeader.EntryCount; i++)
{
int readOffset = Program.SizeOf<VHDX_METADATA_TABLE_HEADER>()
+ i * Program.SizeOf<VHDX_METADATA_TABLE_ENTRY>();
var entry = Program.ToStruct<VHDX_METADATA_TABLE_ENTRY>(metadataBytes, readOffset);
if (entry.IsUser)
{
if (entry.IsRequired)
throw new Exception($"Unknown required metadata item: {entry.ItemId}");
else
continue;
}
else if (entry.IsRequired && !sKnownMetadataItems.Contains(entry.ItemId))
throw new Exception($"Unknown required metadata item: {entry.ItemId}");
//the ArraySegment overload of ToStruct will make sure the entry size matches the data item
var entryBytes = new ArraySegment<byte>(metadataBytes, checked((int)entry.Offset), checked((int)entry.Length));
if (entry.ItemId == METADATA_FILE_PARAMS)
{
fileParams = Program.ToStruct<VHDX_FILE_PARAMETERS>(entryBytes);
}
else if (entry.ItemId == METADATA_VIRTUAL_DISK_SIZE)
{
virtualDiskSize = Program.ToStruct<UInt64>(entryBytes);
}
else if (entry.ItemId == METADATA_LOGICAL_SECTOR_SIZE)
{
logicalSectorSize = Program.ToStruct<UInt32>(entryBytes);
}
}
if (!fileParams.HasValue || !virtualDiskSize.HasValue || !logicalSectorSize.HasValue)
throw new Exception("Missing required metadata!");
outFileParams = fileParams.Value;
outVirtualDiskSize = checked((long)virtualDiskSize.Value);
outLogicalSectorSize = logicalSectorSize.Value;
}