Error in rolling checksum computation

[X-Ryl669]

The rolling checksum property for Adler32 is:

A(n+1) = A(n) - A(1)
B(n+1) = B(n) - n*A(1) - 1

The code does not subtract 1, thus gives wrong output:

syncany/syncany-lib/src/main/java/org/syncany/chunk/Adler32Fingerprinter.java

Line 111 in 2ab2a6f

b -= len * (block[pos] + charOffset);

Please notice that is only applies after the rolling window is full (thus, for n < 48 in this code, the computation of B(n+1) is B(n) - n*A(1)) .