Keypress Dumper (windows)

Long and boring story short: PHP for Windows uses a readline implementation that does not support some functions needed for handling keypresses. This kind of makes it impossible to do basic TUI stuff, since you can only get line inputs (ie you have to press ENTER before input gets processed). Until someone decides to implement the missing functions in WinEditLine, we're stuck. There are other workarounds of course, but much more complicated: writing your own extension to handle keypresses, or doing this via FFI (or even possibly using Direct I/O).

This is a workaround hack for that problem, and only applies if you want to do CLI stuff with PHP in a windows environment.

The workaround

We rely on an EXE file called keypress.exe that does one simple thing: wait for keyboard input, and output a json blob of the key data once a key was pressed. This file can then be called using shell_exec() in php to give a completely transparent "keypress detector". The caveat here is of course that you need to have permissions to exec files in your environment.

Due dilligence

You should probably make a habit of not downloading and running random executables in your environment without some due dilligence, but a precompiled executable is included here for ease of use. But don't trust me; instead look at the code here and build your own:

How to build

1. node --experimental-sea-config sea-config.json
2. npm run build
3. node -e "require('fs').copyFileSync(process.execPath, 'keypress.exe')"
4. signtool.exe remove /s keypress.exe
5. npx postject keypress.exe NODE_SEA_BLOB sea-prep.blob --sentinel-fuse NODE_SEA_FUSE_fce680ab2cc467b6e072b8b5df1996b2

How to use

Build your own keypress.exe (or use the binary provided here) and stick it somewhere safe on your webserver where PHP can exec it. Then something like this should see you through (add your own try/catches and safeguards as you see fit):

<?php
function readkey(): \stdClass {
    return json_decode(shell_exec('/PATH/TO/keypress.exe'));
}

If you were to press ctrl+arrow-up you should get an object back containing this:

stdClass Object
(
    [sequence] => \u001b[1;5A
    [name] => up
    [ctrl] => 1
    [meta] =>
    [shift] =>
    [code] => [A
)

Credits

This extremely simple tool is written in nodejs and is basically just ripping off a small script by Dennis Hackethal. Thanks!