PHP and Linux file names

[mesh2005]

I have a PHP script that takes an input from the user and writes a file with the same name as the input

for example, if the user enters: this is a test a file name is created with the name this is a test.php

The problem happens when the user enters a value that contains characters not allowed in filenames on Linux distributions, how do I convert the value to make sure that it contains only allowed chars?

 

Thank you

[jonsjava]

<?php
$comment = "this is a test";
$clean = str_replace(" ", "" $comment);
?>

[marcus]

characters, as in alphanumeric? you can do a check like:

 

<?php
$string = "this is text";

if(ctype_alnum($string)){
echo "Alphanumeric";
}else {
echo "Not alphanumeric, doing a check...";
$n_string = str_replace(" ",NULL, $string);

if(ctype_alnum($n_string)){
	echo "<br><br>Replacing spaces caused the string to be alphanumeric";
}else {
	echo "<br><br>Replacing spaces caused the string to still be non-alphanumeric!";
}
}
?>

 

[mesh2005]

Thanks guys for your replies. I wanna allow other symbols too like +/- and all possible symbols that won't cause a problem. I usually get errors when the filename is encoded in way that is not understood by Linux, for example the character (’), this character appears as unknown code in the filename, any help?

[Wuhtzu]

Use regular expression:

<?php
$user_input = "this is a test";

if(preg_match("/[a-z0-9 \+_\.-]?/", $user_input)) {
  $file_name = $user_input . ".php";
}
else {
  echo "Invalid characters in filename";
}
?>

 

This will take the $user_input and make sure it only consist of a-z, 0-9, '+', '.', '-' and '_' and has a minimum length of 1.

 

 

 

[mesh2005]

Thanks guys. I found a very useful regex to strip out all non-ASCII chars and this saved the day. Here is it in case anyone needs it:

$string = preg_replace('/[^(\x20-\x7F)]*/','', $string);

[discomatt]

Not all ascii characters are allowed in a filename... '/' in particular could cause some serious issues