fix #2800: return unsigned byte by InputStream API (-1 just if EOF)

[lfcnassif]

Fix #2800. Returns unsigned byte according to method contract, avoiding to return -1 before EOF.

[lfcnassif]

Could someone review this? All modules calling ReadContentInputStream.read() method can be affected and stop processing files before EOF.

[markmckinnon]

Do you have a sample dataset that causes the error that you can provide to expedite testing?

[lfcnassif]

Fix is just an one line change.

[lfcnassif]

Do you have a sample dataset that causes the error that you can provide to expedite testing?

We were affected by this on our project because some modules use the affected method. I don't know if TSK or Autopsy use this public method, but if not it may be used in the future.

To reproduce the error just create a file with a 0xFF as starting byte and more random bytes. Try to read that whole file using just the mentioned method, checking if the returned value is EOF (-1) after each read. The EOF (-1) will be returned in the first read, although the file is not 0 sized.