public EBMLElement(Matroska.File _file, ulong position)
{
if (_file == null)
{
throw new ArgumentNullException("file");
}
if (position > (ulong)(_file.Length - 4))
{
throw new ArgumentOutOfRangeException("position");
}
file = _file;
file.Seek((long)position);
ByteVector vector = file.ReadBlock(1);
Byte header_byte = vector[0];
Byte mask = 0x80, id_length = 1;
while (id_length <= 4 && (header_byte & mask) == 0)
{
id_length++;
mask >>= 1;
}
if (id_length > 4)
{
throw new CorruptFileException("invalid EBML id size");
}
if (id_length > 1)
{
vector.Add(file.ReadBlock(id_length - 1));
}
ebml_id = vector.ToUInt();
vector.Clear();
vector = file.ReadBlock(1);
header_byte = vector[0];
mask = 0x80;
Byte size_length = 1;
while (size_length <= 8 && (header_byte & mask) == 0)
{
size_length++;
mask >>= 1;
}
if (size_length > 8)
{
throw new CorruptFileException("invalid EBML element size");
}
vector[0] &= (Byte)(mask - 1);
if (size_length > 1)
{
vector.Add(file.ReadBlock(size_length - 1));
}
ebml_size = vector.ToULong();
offset = position;
data_offset = offset + id_length + size_length;
}
public string ReadString()
{
if (file == null)
{
return(null);
}
file.Seek((long)data_offset);
ByteVector vector = file.ReadBlock((int)ebml_size);
return(vector.ToString());
}
/// <summary>
/// Read EBML header and data-size if it is an abstract one.
/// It then becomes a non abstract EBML.
/// </summary>
/// <param name="throwException">Throw exception on invalid EBML read if true (Default: false).</param>
/// <returns>True if successful.</returns>
public bool Read(bool throwException = false)
{
if (!Abstract)
{
return(true);
}
if (file == null)
{
throw new ArgumentNullException("file");
}
try
{
var ex = new InvalidOperationException("Invalid EBML format Read");
if (offset >= (ulong)(file.Length) - 1)
{
throw ex;
}
// Prepare for Consitency check
uint ebml_id_check = ebml_id;
ulong ebml_size_check = Size;
file.Seek((long)offset);
// Get the header byte
ByteVector vector = file.ReadBlock(1);
byte header_byte = vector[0];
// Define a mask
byte mask = 0x80, id_length = 1;
// Figure out the size in bytes
while (id_length <= 4 && (header_byte & mask) == 0)
{
id_length++;
mask >>= 1;
}
if (id_length > 4)
{
throw ex;
}
// Now read the rest of the EBML ID
if (id_length > 1)
{
vector.Add(file.ReadBlock(id_length - 1));
}
ebml_id = vector.ToUInt();
vector.Clear();
// Get the size length
vector = file.ReadBlock(1);
header_byte = vector[0];
mask = 0x80;
Byte size_length = 1;
// Iterate through various possibilities
while (size_length <= 8 && (header_byte & mask) == 0)
{
size_length++;
mask >>= 1;
}
if (size_length > 8)
{
size_length = 1; // Special: Empty element (all zero state)
}
else
{
vector[0] &= (Byte)(mask - 1); // Clear the marker bit
}
// Now read the rest of the EBML element size
if (size_length > 1)
{
vector.Add(file.ReadBlock(size_length - 1));
}
ebml_size = vector.ToULong();
// Special: Auto-size (0xFF byte)
if (size_length == 1 && ebml_size == 0x7F)
{
// Resolve auto-size to fill in to its containing element
ulong bound = parent == null ? (ulong)file.Length : parent.Offset + parent.Size;
ebml_size = bound - offset - (ulong)(id_length + size_length);
}
data_offset = offset + id_length + size_length;
// Consistency check: Detect descrepencies between read data and abstract data
if (ebml_id_check != 0 && ebml_id_check != ebml_id)
{
throw ex;
}
if (ebml_size_check != 0 && ebml_size_check != Size)
{
throw ex;
}
return(true);
}
catch (Exception ex)
{
if (throwException)
{
throw ex;
}
return(false);
}
}
/// <summary>
/// Constructs a <see cref="EBMLElement" /> parsing from provided
/// file data.
/// </summary>
/// <param name="_file"><see cref="File" /> instance to read from.</param>
/// <param name="position">Position to start reading from.</param>
public EBMLElement(Matroska.File _file, ulong position)
{
if (_file == null)
{
throw new ArgumentNullException("file");
}
if (position > (ulong)(_file.Length - 4))
{
throw new ArgumentOutOfRangeException("position");
}
// Keep a reference to the file
file = _file;
file.Seek((long)position);
// Get the header byte
ByteVector vector = file.ReadBlock(1);
Byte header_byte = vector [0];
// Define a mask
Byte mask = 0x80, id_length = 1;
// Figure out the size in bytes
while (id_length <= 4 && (header_byte & mask) == 0)
{
id_length++;
mask >>= 1;
}
if (id_length > 4)
{
throw new CorruptFileException("invalid EBML id size");
}
// Now read the rest of the EBML ID
if (id_length > 1)
{
vector.Add(file.ReadBlock(id_length - 1));
}
ebml_id = vector.ToUInt();
vector.Clear();
// Get the size length
vector = file.ReadBlock(1);
header_byte = vector [0];
mask = 0x80;
Byte size_length = 1;
// Iterate through various possibilities
while (size_length <= 8 && (header_byte & mask) == 0)
{
size_length++;
mask >>= 1;
}
if (size_length > 8)
{
throw new CorruptFileException("invalid EBML element size");
}
// Clear the marker bit
vector [0] &= (Byte)(mask - 1);
// Now read the rest of the EBML element size
if (size_length > 1)
{
vector.Add(file.ReadBlock(size_length - 1));
}
ebml_size = vector.ToULong();
offset = position;
data_offset = offset + id_length + size_length;
}
/// <summary>
/// Constructs a <see cref="EBMLElement" /> parsing from provided
/// file data.
/// </summary>
/// <param name="_file"><see cref="File" /> instance to read from.</param>
/// <param name="position">Position to start reading from.</param>
public EBMLElement (Matroska.File _file, ulong position)
{
if (_file == null)
throw new ArgumentNullException ("file");
if (position > (ulong) (_file.Length - 4))
throw new ArgumentOutOfRangeException ("position");
// Keep a reference to the file
file = _file;
file.Seek ((long) position);
// Get the header byte
ByteVector vector = file.ReadBlock (1);
Byte header_byte = vector [0];
// Define a mask
Byte mask = 0x80, id_length = 1;
// Figure out the size in bytes
while (id_length <= 4 && (header_byte & mask) == 0) {
id_length++;
mask >>= 1;
}
if (id_length > 4) {
throw new CorruptFileException ("invalid EBML id size");
}
// Now read the rest of the EBML ID
if (id_length > 1) {
vector.Add (file.ReadBlock (id_length -1));
}
ebml_id = vector.ToUInt ();
vector.Clear ();
// Get the size length
vector = file.ReadBlock (1);
header_byte = vector [0];
mask = 0x80;
Byte size_length = 1;
// Iterate through various possibilities
while (size_length <= 8 && (header_byte & mask) == 0) {
size_length++;
mask >>= 1;
}
if (size_length > 8) {
throw new CorruptFileException ("invalid EBML element size");
}
// Clear the marker bit
vector [0] &= (Byte) (mask - 1);
// Now read the rest of the EBML element size
if (size_length > 1) {
vector.Add (file.ReadBlock (size_length - 1));
}
ebml_size = vector.ToULong ();
offset = position;
data_offset = offset + id_length + size_length;
}