<?php
function mkperms($perms, $return_as_string = false, $filename = '') {
    $perms = explode(',', $perms);
    $generated = array('u'=>array(),'g'=>array(),'o'=>array());
    if(!empty($filename)) {
        $fperms = substr(decoct(fileperms($filename)), 3); // Credits to jchris dot fillionr at kitware dot com
       // Fill array $generated
        $fperms = str_split($fperms);
        $fperms['u'] = $fperms[0]; unset($fperms[0]);
        $fperms['g'] = $fperms[1]; unset($fperms[1]);
        $fperms['o'] = $fperms[2]; unset($fperms[2]);
        foreach($fperms as $key=>$fperm) {
            if($fperm >= 4) {
               $generated[$key]['r'] = true;
               $fperm -= 4;
            }
            if($fperm >= 2) {
               $generated[$key]['w'] = true;
               $fperm -= 2;
            }
            if($fperm >= 1) {
               $generated[$key]['x'] = true;
               $fperm--;
            } 
        }
    }
    foreach($perms as $perm) {
         if(!preg_match('#^([ugo]*)([\+=-])([rwx]+|[\-])$#i', $perm, $matches)) {
             trigger_error('Wrong input format for mkperms'); return 0644;
             // Wrong format => generate default 
         }
         $targets = str_split($matches[1]);
         $addrem = $matches[2];
         $perms_ = str_split($matches[3]);
         $fromTheLoop = 0; // To make sure we clear it only once for direct affectation
         foreach($targets as $target) {
                 foreach($perms_ as $perms__) {
                     if($addrem == '=') {
                         if(!$fromTheLoop) {
                             unset($generated[$target]['r']);
                             unset($generated[$target]['w']);
                             unset($generated[$target]['x']);
                         }
                         $fromTheLoop++;
                         $addrem = '+';
                     }
                     if($perms__ == '-') {
                         unset($generated[$target]['r']);
                         unset($generated[$target]['w']);
                         unset($generated[$target]['x']);
                     } else {
                         if($addrem == '+') {
                             $generated[$target][$perms__] = true;
                         } elseif($addrem == '-') {
                             unset($generated[$target][$perms__]);
                         } elseif($addrem == '=') {
                             
                         }
                     }
                 }
         }
    }
    $generated_chars    = array(0, 0, 0);
    $corresponding      = array('u'=>0, 'g'=>1, 'o'=>2);
    $correspondingperms = array('r'=>4, 'w'=>2, 'x'=>1);

    foreach($generated as $key=>$generated_) {
        foreach($generated_ as $generated__=>$useless) {
            $generated_chars[$corresponding[$key]] += $correspondingperms[$generated__];
        }
    }
    if($return_as_string) return implode($generated_chars);
 else return base_convert(implode($generated_chars), 8, 10);
}
?>