Getting/setting bits and flags

[Brandon Jaeger]

Hi again,

 

I'm trying to get flag information from a row in the table, read it, then assign bits to it.

 

DEFINE ('ADMIN_NEWS'	, 1);
DEFINE ('ADMIN_SERVERS'	, 2);
DEFINE ('ADMIN_ALLIES'	, 4);
DEFINE ('ADMIN_CONTENT'	, ;
DEFINE ('ADMIN_COLUMNS'	, 16);
DEFINE ('ADMIN_USERS'	, 32);

function GetUserFlags($id)
{
$query = "SELECT * FROM users WHERE id = " . $id;
$result = mysql_query($query) or die(mysql_error());

$row = mysql_fetch_assoc($result);

$flags = $row["flags"];

$num = 0;

if(strstr($flags, "a"))
	$flags = ($flags | ADMIN_NEWS);
if(strstr($flags, "b"))
	$flags = ($flags | ADMIN_SERVERS);
if(strstr($flags, "c"))
	$flags = ($flags | ADMIN_ALLIES);
if(strstr($flags, "d"))
	$flags = ($flags | ADMIN_CONTENT);
if(strstr($flags, "e"))
	$flags = ($flags | ADMIN_COLUMNS);
if(strstr($flags, "f"))
	$flags = ($flags | ADMIN_USERS);

return $flags;
}

I'm trying to use it like this:

if(GetUserFlags($_SESSION["userid"]) & ADMIN_NEWS)
  echo "Success!";

 

What am I doing wrong?

 

Thanks.

[DarkWater]

Why don't you actually store the flags that they're allowed as the number in the database...?  Sort of like chmod does for file permissions.

 

EDIT: Example (using your established constants):

 

Give user ALLIES, CONTENT, and USERS privileges:

Flag: ALLIES + CONTENT + USERS =  4 + 8 + 32 = 44

Check if this person can edit users and allies (maybe you need them both on the same page for some reason, so that's why I'm giving this example):

<?php
$flag = 44;
if ($flag & (ADMIN_ALLIES | ADMIN_USERS)) {
  //good!
}
else {
  //nope...
}
?>

[Brandon Jaeger]

The reason I'm not storing the numbers in the database as you said is because I want them to be easily editable for any admin via text input in a form. For example, the admin puts "abcdef" in the form and it inputs it in the database. Then it sums up the bits according to the flags in the user's row and reads them and decides if the user has access or not.

 

How would I do that? <3

[DarkWater]

How about you just make checkboxes and translate that into numbers and then just do simple addition?

[Brandon Jaeger]

Hmm yeah I actually thought about doing that. I'll put that into motion and see how it goes. I shall post my results back here

[Brandon Jaeger]

Okay, so I just did a little tinkering with the flags and I can't get them to work properly.

 

function GetUserFlags($id)
{
$query = "SELECT * FROM users WHERE id = " . $id;
$result = mysql_query($query) or die(mysql_error());

$row = mysql_fetch_assoc($result);

$flags = $row["flags"];

return (int)$flags;
}

if(GetUserFlags($_SESSION["userid"]) & ADMIN_NEWS)
  echo "News flag detected";

 

What I did was added up the sum of all of the flags (63) and inserted that into the DB manually. It doesn't work, though...

 

The session part is correct. I printed them out and it says 1 which is the ID I want.

[DarkWater]

echo $flags and make sure it's what you expect.

[Brandon Jaeger]

Yup. It says 63.

[DarkWater]

I don't mean to be rude by this, but are you sure you included the constants on top?  Because this:

 

<?php
if (63 & 1) {
echo "good!\n";
}
?>

 

Echo's "good!".

[Brandon Jaeger]

There's my problem! The constants are in config.php, which is included in header.php, which is included at the very top of this script.

 

How do you make a global constant? ;x

[DarkWater]

No such thing, they should already be constant.

[Brandon Jaeger]

Shouldn't it already be able to read it from a different file when it's included into the page?

[DarkWater]

Yes.

[Brandon Jaeger]

Hmm well I switched some stuff around and for whatever reason, it works now. Thanks, dude

 

Now to do the checkboxes.