[PHP 8] PemFTP - Fix is_resource() calls on Socket class objects

[ayeshrajans]

WordPress includes a library called PemFTP. The upstream appears to be abandoned, and we have previously made patches in that library (#33432).

In PHP 8, socket_* functions return/accept \Socket class objects that no longer returns true on is_resource() checks: ​https://php.watch/versions/8.0/sockets-sockets-addressinfo

The simplest and backwards compatible approach is simply check $fp !== false in place of is_resource($fp) calls. On all sockets_*() functions that creates a Socket resource, false is returned in case the operation fails, which makes the is_resource() call equivalent to !== false in PHP < 8.0, and buggy in PHP >= 8.0.

[SergeyBiryukov]

Hmm, haven't tested it yet, but as far as I can see looking at the code, the $fp variable here is a file handle created with fopen(), not with any of the socket_*() functions. So it seems like is_resource() checks should still work?

[ayeshrajans]

Thanks for your review @SergeyBiryukov - It indeed turns out that is_resource() is called on file resources only (which will be moved to objects eventually, but nothing to worry for now).

Sorry for wasting your time, and I appreciate your review either way 👍🏼.

[SergeyBiryukov]

No worries! Thanks for the follow-up :)