Recreate UNIX file permissions

[Andy-H]

Hi, I am trying to recreate the UNIX file permissions to test weather today is in a list of days of the week in which a trigger should be active,

 

 

I have a table storing an integer value for the days active and am comparing that with the weekday number, however the results are not as I expect, where am I going wrong?

 

 

// days_active = (32+64) = 96 = Saturday & Sunday || ( 6 & 7)
SELECT * FROM `triggers` WHERE IF(DATE_FORMAT(NOW(), '%w')=0,7,DATE_FORMAT(NOW(), '%u')) & days_active

[trq]

Pardon?

[Andy-H]

I think I've got it worked out, I just need to convert

1 to 1
2 to 2
3 to 4
4 to 8
5 to 16
6 to 32
7 to 64

So I can use a bitwise comparison and check for say monday to friday the number to check against would be 1 + 2 + 4 + 8 + 16 = 31

 

 

So

1  & 31  = true
2  & 31  = true
4  & 31  = true
8  & 31  = true
16 & 31 = true
32 & 31 = false
64 & 31 = false

 

 

Is there a function to make this conversion in MySQL?

[Andy-H]

Sorry, as you may have noticed I'm finding it hard to explain what I am trying to do, perhaps this will help,

 

 

$test = array(1=>1, 2=>2, 3=>4, 4=>8, 5=>16, 6=>32, 7=>64);
for( $i = 1; $i <= 7; $i++)
{
   echo ($test[$i] & 13) . '<br >'; // 13 = 1 + 4 + 8 ( Mon, Wed, Thu)
}

 

 

Outputs:

 

 

1 // true
0 // false
4 // true
8 // true
0 // false
0 // false
0 // false

[/size]So now all I need is a better way to convert 1 to1, 2 to 2, 3 to 4, 5 to 8 etc. than a load of IF() statements. Any idea?

[fenway]

I have no idea what you're talking about -- but it doesn' sounds like mysql.

[Andy-H]

Got it sorted,

 

 

SELECT * FROM `triggers` WHERE POW(2, IF(DATE_FORMAT(NOW(), '%w')=0,7,DATE_FORMAT(NOW(), '%w'))-1) & days_active

[Andy-H]

Ok I'm home now and can explain what I was trying to do, basically, given a set of weekdays on which a data rule should be in place, and a date to compare against them, I needed to extract the weekday and determine if a datarule was active.

 

 

I read a reply a while ago on here that explained how unix file permissions worked, and thought the implementation would be perfect for this scenario.

 

 

So to do it I wrote this script:

 

 

function pow2(&$value)
{
$value = pow(2, $value); // set $value to 2 to the exponent (power) of $value
}
if ( !empty($_POST['days']) )
{
array_map($_POST['days'], 'pow2');
$checkdays = array_sum($_POST['days']);
echo '<pre>'. print_r($_POST['days'],1) .'</pre>'. $checkdays;
}

 

 

<form action="" method="post">
<input type="checkbox" name="days[]" value="0" >Mon <br >
<input type="checkbox" name="days[]" value="1" >Tue <br >
<input type="checkbox" name="days[]" value="2" >Wed <br >
<input type="checkbox" name="days[]" value="3" >Thu <br >
<input type="checkbox" name="days[]" value="4" >Fri <br >
<input type="checkbox" name="days[]" value="5" >Sat <br >
<input type="checkbox" name="days[]" value="6" >Sun <br >
<input type="submit" >
</form>

 

 

So if you were to check Mon, Wed and Thu you would get

 

 

Mon ( 2 ^ 0 ) = 1
Wed ( 2 ^ 2 ) = 4
Thu ( 2 ^ 3 ) = 8
              = 13

So I would set rule_checkdays to 13, now given a date I need to work out the day and use that as the exponent on 2.

(I will use NOW() to replace my date field for this example)

So:

IF(DATE_FORMAT(NOW(), '%w')=0,7,DATE_FORMAT(NOW(), '%w')) - 1       // Mon = 0, Tue = 1, Wed = 2, Thu = 3, Fri = 4, Sat = 5, Sun = 6
POW(2, IF(DATE_FORMAT(NOW(), '%w')=0,7,DATE_FORMAT(NOW(), '%w'))-1) // Mon = 1, Tue = 2, Wed = 4, Thu = 8, Fri = 16, Sat = 32, Sun = 64

So today is Thu so the above would return 8, which represented by binary is:

 

 

00001000

And 13 is

00001101

 

 

So with a bitwise &

 

 

00001101 (13)
&
00001000 ( 
=
00001000 ( (bool[true])

 

 

Now if today were Fri ( 16 ) that would equate to:

00001101 (13)
&
00010000 (16)
=
00000000 (0)(bool[false])

 

 

Or Tue ( 2 )

00001101 (13)
&
00000010 ( 2)
=
00000000 ( 0)(bool[false])

 

 

So now,

POW(2, IF(DATE_FORMAT(NOW(), '%w')=0,7,DATE_FORMAT(NOW(), '%w'))-1) & days_active

 

 

Will result to true if a rule is active today, false if not. Simple as that lol

[Andy-H]

 

Read    = 1

Write    = 2

Ecexcute = 4

 

 

Owner = Read & Write & Execute ( 1 + 2 + 4 ) (7)

Group = Write & Execute        ( 1 + 4    ) (5)

All  = Read                  ( 1        ) (1)

 

 

then something like

7 = 0111
3 = 0011
1 = 0001

 

 

//owner [7]
if ( $action == 'r' )
{
   if ( $premissions & 1 )
   {
      // 7 = 00000111
      &
      // 1 = 00000001
             00000001 = 1 (BOOL[true])
      //allow
   }
}
elseif ( $action == 'w' )
{
   if ( $premissions & 2 )
   {
      // 7 = 00000111
      &
      // 2 = 00000010
             00000010 = 2 (BOOL[true])
      //allow
   }
}
elseif ( $action == 'x' )
{
   if ( $premissions & 4 )
   {
      // 7 = 00000111
      &
      // 4 = 00000100
             00000100 = 4 (BOOL[true])
      //allow
   }
}

//group [5]
if ( $action == 'r' )
{
   if ( $premissions & 1 )
   {
      // 5 = 00000101
      &
      // 1 = 00000001
             00000001 = 1 (BOOL[true])
      //allow
   }
}
elseif ( $action == 'w' )
{
   if ( $premissions & 2 )
   {
      // 5 = 00000101
      &
      // 2 = 00000010
             00000000 = 0 (BOOL[false])
      //deny
   }
}
elseif ( $action == 'x' )
{
   if ( $premissions & 4 )
   {
      // 5 = 00000101
      &
      // 4 = 00000100
             00000100 = 4 (BOOL[true])
      //allow
   }
}

//all [1]
if ( $action == 'r' )
{
   if ( $premissions & 1 )
   {
      // 1 = 00000001
      &
      // 1 = 00000001
             00000001 = 1 (BOOL[true])
      //allow
   }
}
elseif ( $action == 'w' )
{
   if ( $premissions & 2 )
   {
      // 1 = 00000001
      &
      // 2 = 00000010
             00000000 = 0 (BOOL[false])
      //deny
   }
}
elseif ( $action == 'x' )
{
   if ( $premissions & 4 )
   {
      // 1 = 00000001
      &
      // 4 = 00000100
             00000000 = 0 (BOOL[false])
      //deny
   }
}

[fenway]

I have no idea why you're doing any of this.

[Andy-H]

Why how would you do it?

[justinba1010]

Well I think you need to open Terminal, and put chown -hR username /directory to be under a new owner

Is that what you're looking for? Thats what I did to my debugger. chown -hR justin /opt/lampp/htdoc/