public static byte[] Apply(byte[] origin, byte[] delta)
{
uint limit, total = 0;
uint lenSrc = (uint)origin.Length;
uint lenDelta = (uint)delta.Length;
Reader zDelta = new Reader(delta);
limit = zDelta.GetInt();
if (zDelta.GetChar() != '\n')
{
throw new Exception("size integer not terminated by \'\\n\'");
}
Writer zOut = new Writer();
while (zDelta.HaveBytes())
{
uint cnt, ofst;
cnt = zDelta.GetInt();
switch (zDelta.GetChar())
{
case '@':
ofst = zDelta.GetInt();
if (zDelta.HaveBytes() && zDelta.GetChar() != ',')
{
throw new Exception("copy command not terminated by \',\'");
}
total += cnt;
if (total > limit)
{
throw new Exception("copy exceeds output file size");
}
if (ofst + cnt > lenSrc)
{
throw new Exception("copy extends past end of input");
}
zOut.PutArray(origin, (int)ofst, (int)(ofst + cnt));
break;
case ':':
total += cnt;
if (total > limit)
{
throw new Exception("insert command gives an output larger than predicted");
}
if (cnt > lenDelta)
{
throw new Exception("insert count exceeds size of delta");
}
zOut.PutArray(zDelta.a, (int)zDelta.pos, (int)(zDelta.pos + cnt));
zDelta.pos += cnt;
break;
case ';':
byte[] output = zOut.ToArray();
//
// Checksum is optional (2017-10-05)
// http://fossil-scm.org/xfer/info/d3a46b2a45b92bbc
//
//if (cnt != Checksum (output))
// throw new Exception("bad checksum");
if (total != limit)
{
throw new Exception("generated size does not match predicted size");
}
return(output);
default:
throw new Exception("unknown delta operator");
}
}
throw new Exception("unterminated delta");
}