public string name; // Name of the file, padded with 1 to 3 zero bytes to reach
#endregion Fields
#region Methods
public static FileDescriptionPacket Create(PacketHeader header, byte[] bytes, int index)
{
FileDescriptionPacket tmpPacket = new FileDescriptionPacket();
tmpPacket.header = header;
int offset = 0;
Buffer.BlockCopy(bytes, index + offset, tmpPacket.fileid, 0, tmpPacket.fileid.Length * sizeof(byte));
offset += tmpPacket.fileid.Length * sizeof(byte);
Buffer.BlockCopy(bytes, index + offset, tmpPacket.hashfull, 0, tmpPacket.hashfull.Length * sizeof(byte));
offset += tmpPacket.hashfull.Length * sizeof(byte);
Buffer.BlockCopy(bytes, index + offset, tmpPacket.hash16k, 0, tmpPacket.hash16k.Length * sizeof(byte));
offset += tmpPacket.hash16k.Length * sizeof(byte);
tmpPacket.length = BitConverter.ToUInt64(bytes, index + offset);
offset += sizeof(UInt64);
// Name is specific to read since it's dependant of packet.length
int name_offset = index + offset;
int name_size = (int)header.length - header.GetSize() - tmpPacket.fileid.Length * sizeof(byte) - tmpPacket.hashfull.Length * sizeof(byte) - tmpPacket.hash16k.Length * sizeof(byte) - sizeof(UInt64);
byte[] name = new byte[name_size];
Buffer.BlockCopy(bytes, name_offset, name, 0, name_size);
tmpPacket.name = ToolKit.ByteArrayToString(name).TrimEnd('\0');
return tmpPacket;
}
public static FileDescriptionPacket Create(PacketHeader header, byte[] bytes, int index)
{
FileDescriptionPacket tmpPacket = new FileDescriptionPacket();
tmpPacket.header = header;
int offset = 0;
Buffer.BlockCopy(bytes, index + offset, tmpPacket.fileid, 0, tmpPacket.fileid.Length * sizeof(byte));
offset += tmpPacket.fileid.Length * sizeof(byte);
Buffer.BlockCopy(bytes, index + offset, tmpPacket.hashfull, 0, tmpPacket.hashfull.Length * sizeof(byte));
offset += tmpPacket.hashfull.Length * sizeof(byte);
Buffer.BlockCopy(bytes, index + offset, tmpPacket.hash16k, 0, tmpPacket.hash16k.Length * sizeof(byte));
offset += tmpPacket.hash16k.Length * sizeof(byte);
tmpPacket.length = BitConverter.ToUInt64(bytes, index + offset);
offset += sizeof(UInt64);
// Name is specific to read since it's dependant of packet.length
int name_offset = index + offset;
int name_size = (int)header.length - header.GetSize() - tmpPacket.fileid.Length * sizeof(byte) - tmpPacket.hashfull.Length * sizeof(byte) - tmpPacket.hash16k.Length * sizeof(byte) - sizeof(UInt64);
byte[] name = new byte[name_size];
Buffer.BlockCopy(bytes, name_offset, name, 0, name_size);
tmpPacket.name = ToolKit.ByteArrayToString(name).TrimEnd('\0');
return(tmpPacket);
}
internal static FileDescriptionPacket Create(string filename, ulong filesize)
{
// Allocate some extra bytes for the packet in memory so that strlen() can
// be used on the filename. The extra bytes do not get written to disk.
string pad = filename.Length % 4 == 0 ? "" : new string(new char[4 - (filename.Length % 4)]);
FileDescriptionPacket tmpPacket = new FileDescriptionPacket();
tmpPacket.header = new PacketHeader();
tmpPacket.header.magic = Par2FileReader.packet_magic;
tmpPacket.header.hash = new byte[16];
tmpPacket.header.setid = new byte[16];
tmpPacket.header.type = Par2FileReader.filedescriptionpacket_type;
tmpPacket.name = filename + pad;
tmpPacket.fileid = new byte[16];
tmpPacket.hashfull = new byte[16];
tmpPacket.hash16k = new byte[16];
tmpPacket.length = filesize;
tmpPacket.header.length = (ulong)tmpPacket.GetSize();
return(tmpPacket);
}
// Open the source file, compute the MD5 Hash of the whole file and the first
// 16k of the file, and then compute the FileId and store the results
// in a file description packet and a file verification packet.
public bool Open(string filename, ulong blocksize, bool deferhashcomputation)
{
// Get the filename and filesize
targetfilename = filename;
filesize = (ulong)new FileInfo(filename).Length;
// Work out how many blocks the file will be sliced into
blockcount = (uint)((filesize + blocksize - 1) / blocksize);
// Determine what filename to record in the PAR2 files
parfilename = Path.GetFileName(filename);
// Create the Description and Verification packets
FileDescriptionPacket = Packets.FileDescriptionPacket.Create(parfilename, filesize);
FileVerificationPacket = Packets.FileVerificationPacket.Create(blockcount);
// Create the diskfile object
targetfile = new DiskFile();
// Open the source file
if (!targetfile.Open(targetfilename, filesize))
return false;
// Do we want to defer the computation of the full file hash, and
// the block crc and hashes. This is only permitted if there
// is sufficient memory available to create all recovery blocks
// in one pass of the source files (i.e. chunksize == blocksize)
if (deferhashcomputation)
{
// Initialise a buffer to read the first 16k of the source file
uint buffersize = Math.Min((uint)filesize, 16 * 1024);
byte[] buffer = new byte[buffersize];
// Read the data from the file
if (!targetfile.Read(0, buffer, buffersize))
{
targetfile.Close();
return false;
}
// Compute the hash of the data read from the file
// Store the hash in the descriptionpacket and compute the file id
MD5 md5Hasher = MD5.Create();
FileDescriptionPacket.hash16k = md5Hasher.ComputeHash(buffer);
// Compute the fileid and store it in the verification packet.
FileDescriptionPacket.ComputeFileId();
FileVerificationPacket.fileid = (byte[])FileDescriptionPacket.fileid.Clone();
//// Allocate an MD5 context for computing the file hash
//// during the recovery data generation phase
contextfull = MD5.Create();
//contextfull = new MD5Context;
}
else
{
// Compute 16k MD5 hash
using (BinaryReader br = new BinaryReader(new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read)))
{
MD5 md5Hasher = MD5.Create();
byte[] buffer16k = br.ReadBytes(16 * 1024);
FileDescriptionPacket.hash16k = md5Hasher.ComputeHash(buffer16k);
}
// Compute the fileid and store it in the verification packet.
FileDescriptionPacket.ComputeFileId();
FileVerificationPacket.fileid = (byte[])FileDescriptionPacket.fileid.Clone();
// Compute full file MD5 hash & block CRC32 and MD5 hashes
//long readSize = 5 * (long)blocksize;
long readSize = (long)blocksize;
long fileSize = new FileInfo(filename).Length;
long nbSteps = fileSize / readSize;
long remaining = fileSize % readSize;
uint blocknumber = 0;
// TODO : switch to async filestream
using (BinaryReader br = new BinaryReader(new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read)))
{
MD5 md5FullHasher = MD5.Create();
MD5 md5Hasher = MD5.Create();
//FastCRC32.FastCRC32 crc32 = new FastCRC32.FastCRC32(blocksize);
FastCRC32.FastCRC32 crc32 = FastCRC32.FastCRC32.GetCRC32Instance(blocksize);
byte[] blockHash = new byte[16];
uint blockCRC32 = 0;
for (int i = 0; i < nbSteps + 1; ++i)
{
byte[] buffer = br.ReadBytes((int)(i == nbSteps ? remaining : readSize));
// Global MD5 hash
if (i == nbSteps)
md5FullHasher.TransformFinalBlock(buffer, 0, buffer.Length);
else
md5FullHasher.TransformBlock(buffer, 0, buffer.Length, null, 0);
//for (uint j = 0; j < 5; ++j)
//{
// Block MD5 hash & CRC32
uint length = (uint)blocksize;
//if (i == nbSteps && j == 4)
//if (i == nbSteps && (buffer.Length - (uint)(j * blocksize)) < (int)blocksize)
if (i == nbSteps && remaining != 0)
{
// We need arry padding since calculation **MUST** always be done on blocksize-length buffers
byte[] smallBuffer = buffer;
buffer = new byte[blocksize];
Buffer.BlockCopy(smallBuffer, 0, buffer, 0, smallBuffer.Length);
}
blockCRC32 = crc32.CRCUpdateBlock(0xFFFFFFFF, (uint)blocksize, buffer, 0) ^ 0xFFFFFFFF;
blockHash = md5Hasher.ComputeHash(buffer, 0, (int)blocksize);
//Console.WriteLine("blocknumber:{0},hash:{1},crc32:{2}", blocknumber, blockHash, blockCRC32);
FileVerificationPacket.SetBlockHashAndCRC(blocknumber++, blockHash, blockCRC32);
//}
}
FileDescriptionPacket.hashfull = md5FullHasher.Hash;
}
}
return true;
}
internal static FileDescriptionPacket Create(string filename, ulong filesize)
{
// Allocate some extra bytes for the packet in memory so that strlen() can
// be used on the filename. The extra bytes do not get written to disk.
string pad = filename.Length % 4 == 0 ? "" : new string(new char[4 - (filename.Length % 4)]);
FileDescriptionPacket tmpPacket = new FileDescriptionPacket();
tmpPacket.header = new PacketHeader();
tmpPacket.header.magic = Par2FileReader.packet_magic;
tmpPacket.header.hash = new byte[16];
tmpPacket.header.setid = new byte[16];
tmpPacket.header.type = Par2FileReader.filedescriptionpacket_type;
tmpPacket.name = filename + pad;
tmpPacket.fileid = new byte[16];
tmpPacket.hashfull = new byte[16];
tmpPacket.hash16k = new byte[16];
tmpPacket.length = filesize;
tmpPacket.header.length = (ulong)tmpPacket.GetSize();
return tmpPacket;
}