private long WriteToDbFile(DbFileResource dbFile, byte[] data, byte[] datalen, byte[] hash, int stublen, long position)
{
bool isAppend = position < 0 || position >= dbFile.length;
if (isAppend)
{
position = dbFile.stream.Seek(0, SeekOrigin.End);
}
else
{
dbFile.stream.Position = position;
}
dbFile.stream.Write(datalen, 0, 4);
dbFile.stream.Write(data, 0, data.Length);
dbFile.stream.Write(hash, 0, 16);
int s;
for (s = stublen; s > stub.Length; s -= stub.Length)
{
dbFile.stream.Write(stub, 0, stub.Length);
}
dbFile.stream.Write(stub, 0, s);
if (isAppend)
{
dbFile.length += data.Length + 20 + stublen;
}
return(position);
}
/// <summary> If position == -1 write to end of file, else dataitems will be writed to position </summary>
/// <returns> Position in file where dataitems were saved. It equals to parameter position, if it was valid,
/// else if parameter position was equals -1 or other not valid position, method returns new position of dataitems. </returns>
private long WriteToDbFile(DbFileResource dbFile, int capacity, byte[] data, long position)
{
var len = BitConverter.GetBytes(data.Length);
var hash = new MD5CryptoServiceProvider().ComputeHash(data);
lock (dbFile)
return(WriteToDbFile(dbFile, data, len, hash, capacity - data.Length, position));
}
private byte[] ReadFromDbFile(DbFileResource dbFile, int capacity, long position)
{
byte[] data, hash;
lock (dbFile)
ReadFromDbFile(dbFile, capacity, position, out data, out hash);
var control = new MD5CryptoServiceProvider().ComputeHash(data);
if (!control.SequenceEqual(hash))
{
return(null);
}
return(data);
}
/// <summary>
/// Need locking dbFile before calling!
/// </summary>
private void ReadFromDbFile(DbFileResource dbFile, int capacity, long position, out byte[] data, out byte[] hash)
{
data = null;
var buf = hash = new byte[16];
dbFile.stream.Position = position;
dbFile.stream.Read(buf, 0, 4);
int len = BitConverter.ToInt32(buf, 0);
if (len > capacity || len < 0)
{
return;
}
data = new byte[len];
dbFile.stream.Read(data, 0, len);
dbFile.stream.Read(buf, 0, 16);
}
private long WriteToDbFile(DbFileResource dbFile, byte[] data, byte[] datalen, byte[] hash, int stublen, long position)
{
bool isAppend = position < 0 || position >= dbFile.length;
if (isAppend)
position = dbFile.stream.Seek(0, SeekOrigin.End);
else
dbFile.stream.Position = position;
dbFile.stream.Write(datalen, 0, 4);
dbFile.stream.Write(data, 0, data.Length);
dbFile.stream.Write(hash, 0, 16);
int s;
for (s = stublen; s > stub.Length; s-=stub.Length)
dbFile.stream.Write(stub, 0, stub.Length);
dbFile.stream.Write(stub, 0, s);
if (isAppend) dbFile.length += data.Length + 20 + stublen;
return position;
}
/// <summary> If position == -1 write to end of file, else dataitems will be writed to position </summary>
/// <returns> Position in file where dataitems were saved. It equals to parameter position, if it was valid,
/// else if parameter position was equals -1 or other not valid position, method returns new position of dataitems. </returns>
private long WriteToDbFile(DbFileResource dbFile, int capacity, byte[] data, long position)
{
var len = BitConverter.GetBytes(data.Length);
var hash = new MD5CryptoServiceProvider().ComputeHash(data);
lock (dbFile)
return WriteToDbFile(dbFile, data, len, hash, capacity - data.Length, position);
}
/// <summary>
/// Need locking dbFile before calling!
/// </summary>
private void ReadFromDbFile(DbFileResource dbFile, int capacity, long position, out byte[] data, out byte[] hash)
{
data = null;
var buf = hash = new byte[16];
dbFile.stream.Position = position;
dbFile.stream.Read(buf, 0, 4);
int len = BitConverter.ToInt32(buf, 0);
if (len > capacity || len < 0) return;
data = new byte[len];
dbFile.stream.Read(data, 0, len);
dbFile.stream.Read(buf, 0, 16);
}
private byte[] ReadFromDbFile(DbFileResource dbFile, int capacity, long position)
{
byte[] data, hash;
lock (dbFile)
ReadFromDbFile(dbFile, capacity, position, out data, out hash);
var control = new MD5CryptoServiceProvider().ComputeHash(data);
if (!control.SequenceEqual(hash)) return null;
return data;
}
