A simple PHP extension that allows you to get the FD of a stream resource.
git clone https://github.com/Encritary/streamfd.git
cd streamfd
phpize
./configure --enable-streamfd
make && make test && sudo make install
The extension adds only one new PHP function:
streamfd(resource $stream) : int|bool
It will return the file descriptor (a positive integer) of the given stream resource, or false if an error occurs.