Bug: Utils.ReadAllBytes reads too few bytes when position > 0

[dkropachev]

Description

Utils.ReadAllBytes(Stream stream, int position) has an off-by-one bug in the byte count passed to ReadExactly:

// src/Cassandra/Utils.cs:187-192
public static byte[] ReadAllBytes(Stream stream, int position)
{
    var buffer = new byte[stream.Length - position];
    stream.Position = position;
    stream.ReadExactly(buffer, 0, buffer.Length - position); // BUG
    return buffer;
}

buffer.Length is already stream.Length - position, so buffer.Length - position evaluates to stream.Length - 2 * position. When position > 0, this reads fewer bytes than the buffer was allocated for, leaving trailing zeroes and silently returning corrupt data.

Example: stream.Length = 10, position = 4 → buffer is 6 bytes, but only 2 bytes are read.

Current impact

Low — all current callers pass position = 0, which makes the math correct by coincidence. The bug is latent but will trigger if anyone calls this method with a non-zero position in the future.

Fix

Change the third argument from buffer.Length - position to buffer.Length:

stream.ReadExactly(buffer, 0, buffer.Length);

This bug predates the next-major/drop-old-runtimes branch (the old Utils.ReadExactly wrapper had the same wrong count), but now is a good time to fix it since the method is already being touched.