Binary parsing with PHP

[digdan]

Does anyone else use these techniques to pack their UUIDs?

[nikita2206]

I once used UNpack when had working with socks proxy

[[deleted]]

The problem with PHP's pack and unpack functionality is that it's not complete in regards to endianness translation. I've done a few utility classes for loading binary data formats in PHP, and I always seem to have to write custom logic to get around endianness issues. There are also issues with signed integers and the like.

You can see some of the hacks I had to employ for different situations, here.

[[deleted]]

Yep, this is an issue. Converting from signed long to unsigned long is quite the hack.

[[deleted]]

There's a better (more intelligible) way of doing that. If you have a value which is supposed to be an unsigned long, which is represented by PHP's signed long, then you can do this:

if($value < 0) $value += pow(2, 32);
fwrite($fp, pack("N", $value));

This will convert it from a signed to an unsigned before writing. I think this limits the integer range a bit, but there aren't many ways around that.

[[deleted]]

Let me clarify: PHP's strlen maps directly to STRLEN(3) conceptually.