/// <summary>
/// Reads a record from the file system.
/// </summary>
/// <param name="item">The item to read the data into.</param>
/// <param name="volumeIndex">The index of the volume the file resides on.</param>
/// <param name="lad">The long allocation descriptor of the file.</param>
/// <param name="numRecurseAllowed">The number of recursions allowed before the method fails.</param>
/// <returns>Returns true if the item and all sub items were read correctly.</returns>
private bool ReadRecord(UdfRecord item, int volumeIndex, LongAllocationDescriptor lad, int numRecurseAllowed)
{
if (numRecurseAllowed-- == 0)
{
return(false);
}
LogicalVolume vol = this.LogicalVolumes[volumeIndex];
Partition partition = this.Partitions[vol.PartitionMaps[lad.Location.PartitionReference].PartitionIndex];
int key = lad.Location.Position;
if (partition.Map.ContainsKey(key))
{
// Item already in the map, just look it up instead of reading it from the image.
item.VolumeIndex = partition.Map[key].VolumeIndex;
item.PartitionIndex = partition.Map[key].PartitionIndex;
item.Extents = partition.Map[key].Extents;
item._size = partition.Map[key]._size;
item.Key = key;
}
else
{
item.VolumeIndex = volumeIndex;
item.PartitionIndex = vol.PartitionMaps[lad.Location.PartitionReference].PartitionIndex;
item.Key = key;
if (!partition.Map.Set(key, item) || !this.ReadRecordData(item, volumeIndex, lad, numRecurseAllowed))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Validates that the volume has a valid partition.
/// </summary>
/// <param name="volume">The volume to validate.</param>
/// <returns>Returns true if the volume is valid.</returns>
private bool ValidateVolumePartition(LogicalVolume volume)
{
for (int i = 0; i < volume.PartitionMaps.Count; i++)
{
PartitionMap map = volume.PartitionMaps[0];
bool found = false;
foreach (var partition in this.Partitions)
{
if (partition.Number == map.PartitionNumber)
{
// partition can only be member of one volume
if (partition.VolumeIndex >= 0)
{
return(false);
}
// Add cross references between partitions and volumes.
map.PartitionNumber = this.Partitions.IndexOf(partition);
partition.VolumeIndex = this.LogicalVolumes.IndexOf(volume);
found = true;
}
}
if (!found)
{
return(false);
}
}
return(true);
}
/// <summary>
/// Reads a logical volume descriptor from the buffer.
/// </summary>
/// <param name="buffer">The buffer to read the data from.</param>
/// <returns>Returns true if the descriptor is valid.</returns>
private bool ReadLogicalDescriptor(byte[] buffer)
{
LogicalVolume volume = new LogicalVolume();
volume.Id.Parse(84, buffer);
volume.BlockSize = UdfHelper.Get32(212, buffer);
if (volume.BlockSize < VirtualSectorSize || volume.BlockSize > MaxExtents)
{
return(false);
}
volume.FileSetLocation.Parse(248, buffer);
int numPartitionMaps = UdfHelper.Get32(268, buffer);
if (numPartitionMaps > MaxPartitions)
{
return(false);
}
int position = 440;
for (int index = 0; index < numPartitionMaps; index++)
{
if (position + 2 > SectorSize)
{
return(false);
}
PartitionMap pm = new PartitionMap();
pm.Type = buffer[position];
byte length = buffer[position + 1];
if (position + length > SectorSize)
{
return(false);
}
if (pm.Type == 1)
{
if (position + 6 > SectorSize)
{
return(false);
}
pm.PartitionNumber = UdfHelper.Get16(position + 4, buffer);
}
else
{
return(false);
}
position += length;
pm.PartitionIndex = volume.PartitionMaps.Count;
volume.PartitionMaps.Add(pm);
}
this.LogicalVolumes.Add(volume);
return(true);
}
/// <summary>
/// Validates to ensure the extent is in a valid format.
/// </summary>
/// <param name="volumeIndex">The volume index.</param>
/// <param name="partitionReference">The partition reference.</param>
/// <param name="blockPosition">The current block position.</param>
/// <param name="length">The length of the extent.</param>
/// <returns>Returns true if the extent is valid.</returns>
private bool CheckExtent(int volumeIndex, int partitionReference, int blockPosition, int length)
{
LogicalVolume volume = this.LogicalVolumes[volumeIndex];
Partition partition = this.Partitions[volume.PartitionMaps[partitionReference].PartitionIndex];
long offset = ((long)partition.Position << SectorSizeLog) + ((long)blockPosition * volume.BlockSize);
return((offset + length) <= (((long)partition.Position + partition.Length) << SectorSizeLog));
}
/// <summary>
/// Reads data from the stream.
/// </summary>
/// <param name="volumeIndex">The volume index of the data.</param>
/// <param name="partitionReference">The partition reference.</param>
/// <param name="blockPosition">The block position of the data to read.</param>
/// <param name="length">The length of the data to read.</param>
/// <param name="buffer">The buffer to contain the data.</param>
/// <returns>Returns true if the data was read successfully.</returns>
private bool ReadData(int volumeIndex, int partitionReference, int blockPosition, int length, byte[] buffer)
{
if (!this.CheckExtent(volumeIndex, partitionReference, blockPosition, length))
{
return(false);
}
LogicalVolume volume = this.LogicalVolumes[volumeIndex];
Partition partition = this.Partitions[volume.PartitionMaps[partitionReference].PartitionIndex];
this.stream.Seek(((long)partition.Position << SectorSizeLog) + (blockPosition * volume.BlockSize), (int)SeekOrigin.Begin, IntPtr.Zero);
return(this.stream.ReadSafe(buffer, length));
}
/// <summary>
/// Reads the data from the image for a record.
/// </summary>
/// <param name="item">The item to read the data into.</param>
/// <param name="volumeIndex">The index of the volume the file resides on.</param>
/// <param name="lad">The long allocation descriptor of the file.</param>
/// <param name="numRecurseAllowed">The number of recursions allowed before the method fails.</param>
/// <returns>Returns true if the record was read successfully.</returns>
private bool ReadRecordData(UdfRecord item, int volumeIndex, LongAllocationDescriptor lad, int numRecurseAllowed)
{
if (this.itemCount > MaxItems)
{
return(false);
}
LogicalVolume volume = this.LogicalVolumes[volumeIndex];
if (lad.Length != volume.BlockSize)
{
return(false);
}
// Read the record.
int size = lad.Length;
byte[] buffer = new byte[size];
if (!this.ReadData(volumeIndex, lad, buffer))
{
return(false);
}
// Validate the tag is a file.
VolumeTag tag = new VolumeTag();
tag.Parse(0, buffer, size);
if (tag.Identifier != (short)VolumeDescriptorType.File)
{
return(false);
}
// Validate the IcbTage indicates file or directory.
item.IcbTag.Parse(16, buffer);
if (item.IcbTag.FileType != IcbFileType.Directory && item.IcbTag.FileType != IcbFileType.File)
{
return(false);
}
item.Parse(buffer);
int extendedAttrLen = UdfHelper.Get32(168, buffer);
int allocDescriptorsLen = UdfHelper.Get32(172, buffer);
if ((extendedAttrLen & 3) != 0)
{
return(false);
}
int position = 176;
if (extendedAttrLen > size - position)
{
return(false);
}
position += extendedAttrLen;
IcbDescriptorType desctType = item.IcbTag.DescriptorType;
if (allocDescriptorsLen > size - position)
{
return(false);
}
if (desctType == IcbDescriptorType.Inline)
{
// If the file data is inline, read it in now since we have it.
item.IsInline = true;
item.InlineData = UdfHelper.Readbytes(position, buffer, allocDescriptorsLen);
}
else
{
// Otherwise read the information about where the file is located for later.
item.IsInline = false;
item.InlineData = new byte[0];
if ((desctType != IcbDescriptorType.Short) && (desctType != IcbDescriptorType.Long))
{
return(false);
}
for (int index = 0; index < allocDescriptorsLen;)
{
FileExtent extent = new FileExtent();
if (desctType == IcbDescriptorType.Short)
{
if (index + 8 > allocDescriptorsLen)
{
return(false);
}
ShortAllocationDescriptor sad = new ShortAllocationDescriptor();
sad.Parse(position + index, buffer);
extent.Position = sad.Position;
extent.Length = sad.Length;
extent.PartitionReference = lad.Location.PartitionReference;
index += 8;
}
else
{
if (index + 16 > allocDescriptorsLen)
{
return(false);
}
LongAllocationDescriptor ladNew = new LongAllocationDescriptor();
ladNew.Parse(position + index, buffer);
extent.Position = ladNew.Location.Position;
extent.PartitionReference = ladNew.Location.PartitionReference;
extent.Length = ladNew.Length;
index += 16;
}
item.Extents.Add(extent);
}
}
if (item.IcbTag.IsDirectory)
{
if (!item.CheckChunkSizes() || !this.CheckItemExtents(volumeIndex, item))
{
return(false);
}
buffer = new byte[0];
if (!this.ReadFromFile(volumeIndex, ref item, ref buffer))
{
return(false);
}
item._size = 0;
item.Extents.Clear();
size = buffer.Length;
int processedTotal = 0;
int processedCur = -1;
while (processedTotal < size || processedCur == 0)
{
UdfFileInformation fileId = new UdfFileInformation();
fileId.Parse(processedTotal, buffer, (size - processedTotal), ref processedCur);
if (!fileId.IsItLinkParent)
{
// Recursively read the contentst of the drirectory
UdfRecord fileItem = new UdfRecord();
fileItem.Id = fileId.Identifier;
if (fileItem.Id.Data != null)
{
this.fileNameLengthTotal += fileItem.Id.Data.Length;
}
if (this.fileNameLengthTotal > MaxFileNameLength)
{
return(false);
}
fileItem._Parent = item;
item.Subitems.Add(fileItem);
if (item.Subitems.Count > MaxFiles)
{
return(false);
}
this.ReadRecord(fileItem, volumeIndex, fileId.Icb, numRecurseAllowed);
}
processedTotal += processedCur;
}
}
else
{
if (item.Extents.Count > MaxExtents - this.numExtents)
{
return(false);
}
this.numExtents += item.Extents.Count;
if (item.InlineData.Length > MaxInlineExtentsSize - this.inlineExtentsSize)
{
return(false);
}
this.inlineExtentsSize += item.InlineData.Length;
}
this.itemCount++;
return(true);
}