Weird Bitwise Bug

[gmoeck]

In doing user permissions, I'm having a weird bug with a bitwise and. The values are being stored correctly, yet when the 'and' is done the value that returns varies by which server the command is done on. Example:

 

$user["permissions"] = 54975580511 //0x7FFFFFDF47

$CLIENT_VIEW = 4294967296 // 0x10000000

 

$user["permissions"] & $CLIENT_VIEW => 0 on one of our servers.

 

Any suggestions?

 

[MadTechie]

$user["permissions"] = 54975580511 //0x7FFFFFDF47

well first off 0x7FFFFFDF47= 549755805511

 

you say on one of your servers you get 0

but i don't see how your get any other result

 

i assume you was expecting 34 !

[Barand]

I would expect the answer to be same as $CLIENT_VIEW although my server gives 0

 

<?php
echo base_convert('7FFFFFDF47', 16,2);
echo '<br>';
echo '000000' . base_convert('4294967296', 10,2);


?>

-->

111111111111111111111111101111101000111
000000100000000000000000000000000000000 

[gmoeck]

I would expect the answer to be same as $CLIENT_VIEW although my server gives 0

 

<?php
echo base_convert('7FFFFFDF47', 16,2);
echo '<br>';
echo '000000' . base_convert('4294967296', 10,2);


?>

-->

111111111111111111111111101111101000111
000000100000000000000000000000000000000 

That is exactly what I would expect as well, yet one of our servers gives 0, just like yours. Any idea what might yield this result? Why would the server give 0, and not the value of $CLIENT_VIEW?

 

In binary, I would expect 000000100000000000000000000000000000000, which should be non-zero.

[Barand]

I guess the 31 bit (signed int) limit has something to do with it. The "1" is bit 33 if I counted correctly.

[MadTechie]

i used

<?php
$a = 549755805511;
$b = 004294967296;

$a = base_convert($a, 10, 2);
$b = base_convert($b, 10, 2);

$c = base_convert(($a & $b), 2, 10);

var_dump($c);

?>

[Barand]

Actually that's very close to a working solution. You just need to make $a and $b string values

 

<?php

$a = '549755805511';
$b = '004294967296';

$a = base_convert($a, 10, 2);
$b = base_convert($b, 10, 2);

$c = base_convert(($a & $b), 2, 10);

var_dump($c);     // string(10) "4294967296" 

?>