The second argment to calloc(3) should be the size, make it so.
While here be a little bit more cautious in fifolog_reader_open()
to protect in the unlikely event of an overflowed allocation.
MFC after: 3 weeks
Quoth the man-page:
Fifologs provide a compact round-robin circular storage for recording
text and binary information to permanent storage in a bounded and pre-
dictable fashion, time and space wise.
Not yet connected to the build, but feel free to test & review.