Hi this is my first post. Hello Monks!
Hello! And welcome. Nice first post.
Given that some OSes treat binary and text files differently (the latter messing around with line endings as you said in your first post), I think you really need a $mode argument to the Digest::SHA::addfile($filename [, $mode]) method.
It's intended as a convenience feature much like the ASCII and IMAGE (BINARY) modes of FTP. But I would argue it's a mis-feature—or at least a misplaced feature. It's akin to the line ending translation feature of FTP, which proved over time to do more harm than good. It was a fine feature in the early days of the Internet when FTP was used mostly by savvy technologists to bandy about lots of source code (plain text). But later, it just caused endless trouble for naïve Internet users who mostly used FTP to transfer large ZIP files and such. ASCII mode became the wrong default. Much bandwidth was wasted transferring large binary files multiple times because they all-too-often got corrupted the first time.
It might cause fewer problems if Digest::SHA::addfile() defaulted to binary mode.
I think it essentially does. From my reading of the confusing documentation, the right thing to do in the general case (i.e., the case where you don't want line ending translation to happen) is not to use the mode argument of Digest::SHA::addfile() at all. It states:
"By default, $filename is simply opened and read; no special modes or I/O disciplines are used."