If you are guaranteed to only read your OS's native formats, then you wouldn't need this routine at all. Therefore, I assumed the OP has this code in place because the script running on one OS is likely to read files created by several different OSes.

So, I stand by my statement: if you read a file with Mac line endings (say, on a Unix box), using the code in the top node would read the whole file, since $/ would be looking for a Unix-style line-endings, which don't contain "\r";

Your point about using the hex values for setting is a good one to remember, but the code as I wrote it automatically accounts for that. As for using the same line endings for output as have been determined for input, $\ = $/ is sufficient.