Currently, when getting the LZWStatus::NoProgress from the underlying
weezl library, tiff checks that no input bytes were read and no
output bytes were written. Although this is according to what the
weezl library mentions in their doc-comment, it's not what the real
result always looks like.
Our fuzzer found input that triggered exactly this case, where the LZW
reader is able to write some output byte before hitting the NoProgress
status.
This change removes the assert, as the resulting action is anyways to return
an error that can be handled by the caller.
At the moment when writing Byte strings into tiff metadata sections (like
for XMP metadata) and try to read it with this crate, you will find your
characters as a Value::UnsignedBig, holding the char value with padding.
This seems wrong and we should instead return actual Value::Bytes.
Bastian Kersting