Alphanumeric (sha1) Semaphore in PHP?

Question

PHP's "shm_get" function requires an integer semaphore key, which I realise to be a restriction of the underlying OS.

I am using the "sha1" function to hash some user input and using the hash to uniquely identify a number of resulting files and and background processes.

Is there a way to convince shm_get to accept an alphanumeric key or to convert a sha1 hash to an acceptable integer?

Answer 1

You can convert a hexadecimal number into a decimal number by using hexdec()

However if you have got a large number in your hash, this won't return an integer. But you need an integer. So you might want to cut it apart and only use a part of the hash.

$hash = sha1('http://www.hashcat.net/');
$hash = substr($hash, 0, 15); // ok on 64bit systems
$number = (int) hexdec($hash); // cap to PHP_INT_MAX anyway
var_dump($hash, $number);