is_writeable> <is_uploaded_file
Last updated: Fri, 03 Feb 2012

is_writable

(PHP 4, PHP 5)

is_writable — Diz se o arquivo pode ser modificado

Descrição

bool is_writable ( string $filename )

Retorna TRUE se o arquivo em filename existe e pode ser modificado. O argumento filename pode ser um diretório, permitindo que você verifique se o diretório tem permissão de escrita.

Lembre-se que o PHP pode acessar o arquivo como o usuário com o qual o servidor web é executado (geralmente 'nobody'). Limitações de Safe Mode não são levadas em conta antes do PHP 5.1.5.

Parâmetros

filename

O arquivo sendo verificado.

Valor Retornado

Retorna TRUE se o arquivo em filename existe e pode ser modificado.

Exemplos

Exemplo #1 Exemplo de is_writable()

<?php
$filename = 'teste.txt';
if (is_writable($filename)) {
    echo 'O arquivo possui permissão de escrita';
} else {
    echo 'O arquivo não possui permissão de escrita';
}
?>

Notas

Nota: O resultado desta função é cacheada. Veja clearstatcache() para mais detalhes.

Dica

A partir do PHP 5.0.0, esta função também pode ser utilizada com alguns wrappers URL. Veja Supported Protocols and Wrappers para uma lista de quais wrappers são suportados pela família de funções stat().

Veja Também



is_writeable> <is_uploaded_file
Last updated: Fri, 03 Feb 2012
 
User Contributed Notes
is_writable
gr
05-Oct-2010 12:32
The results of this function seems to be not cached :
Tested on linux and windows

<?php
chmod($s_pathFichier, 0400);
echo'<pre>';var_dump(is_writable($s_pathFichier));echo'</pre>';
chmod($s_pathFichier, 04600);
echo'<pre>';var_dump(is_writable($s_pathFichier));echo'</pre>';
exit;
?>
starrychloe at yahoo dot com
10-Feb-2008 03:50
To Darek and F Dot: About group permissions, there is this note in the php.ini file:
; By default, Safe Mode does a UID compare check when
; opening files. If you want to relax this to a GID compare,
; then turn on safe_mode_gid.
safe_mode_gid = Off
wuhai
25-Sep-2007 06:46
I was trying to create a new file using fwrite, and i had the following error.  Any idea?
Warning: fwrite(): supplied argument is not a valid stream resource in
legolas558 d0t users dot sf dot net
02-Mar-2007 09:18
This is the latest version of is__writable() I could come up with.
It can accept files or folders, but folders should end with a trailing slash! The function attempts to actually write a file, so it will correctly return true when a file/folder can be written to when the user has ACL write access to it.

<?php
function is__writable($path) {
//will work in despite of Windows ACLs bug
//NOTE: use a trailing slash for folders!!!
//see http://bugs.php.net/bug.php?id=27609
//see http://bugs.php.net/bug.php?id=30931

    if ($path{strlen($path)-1}=='/') // recursively return a temporary file path
        return is__writable($path.uniqid(mt_rand()).'.tmp');
    else if (is_dir($path))
        return is__writable($path.'/'.uniqid(mt_rand()).'.tmp');
    // check tmp file for read/write capabilities
    $rm = file_exists($path);
    $f = @fopen($path, 'a');
    if ($f===false)
        return false;
    fclose($f);
    if (!$rm)
        unlink($path);
    return true;
}
?>
haccel at email dot com
03-Aug-2006 02:51
Ooooops, sorry! My mistake. is__writable should be:

<?php

function is__writable($path)
{

   if ($path{strlen($path)-1}=='/') //Start function again with tmp file...
     
       return is__writable($path.uniqid(mt_rand()).'.tmp');
 
   elseif (ereg('.tmp', $path))
   { //Check tmp file for read/write capabilities
     
       if (!($f = @fopen($path, 'w+')))
           return false;
       fclose($f);
       unlink($path);
       return true;

   }
   else //We have a path error.
     
       return 0; // Or return error - invalid path...

}

?>

The original could've deleted a folder if the path was invalid  to start with (no trailing slash..) and the folder was writable to begin with...
haccel at email dot com
02-Aug-2006 05:56
Be careful of legolas558 dot sourceforge comma net's example, try this instead:

<?php

function is__writable($path)
{

    if ($path{strlen($path)-1}=='/')
       
        return is__writable($path.uniqid(mt_rand()).'.tmp');
   
    elseif (file_exists($path) && ereg('.tmp', $path))
    {
       
        if (!($f = @fopen($path, 'w+')))
            return false;
        fclose($f);
        unlink($path);
        return true;

    }
    else
       
        return 0; // Or return error - invalid path...

}

?>
legolas558 dot sourceforge comma net
12-Jul-2006 10:17
Since looks like the Windows ACLs bug "wont fix" (see http://bugs.php.net/bug.php?id=27609) I propose this alternative function:

<?php

function is__writable($path) {

if ($path{strlen($path)-1}=='/')
    return is__writable($path.uniqid(mt_rand()).'.tmp');

if (file_exists($path)) {
    if (!($f = @fopen($path, 'r+')))
        return false;
    fclose($f);
    return true;
}

if (!($f = @fopen($path, 'w')))
    return false;
fclose($f);
unlink($path);
return true;
}

?>

It should work both on *nix and Windows

NOTE: you must use a trailing slash to identify a directory
Nils Kuebler
18-Apr-2006 12:15
this one recursivly checks if a folder and all its contents are writeable

<?php
function is_removeable($dir)
{
   $folder = opendir($dir);
   while($file = readdir( $folder ))
    if($file != '.' && $file != '..' &&
        ( !is_writable(  $dir."/".$file  ) ||
        (  is_dir(   $dir."/".$file   ) && !is_removeable(   $dir."/".$file   )  ) ))
   {
    closedir($dir);
    return false;
   }
   closedir($dir);
   return true;
}
?>
greg at gregwhitescarver dotcalm
07-Feb-2006 04:55
In response to Darek:

We have two servers: one running PHP 5.0.4 and Apache 1.3.33, the other running PHP 4.3.5 and Apache 1.3.27.  The PHP 4 server exhibits the behavior you are describing, with is_writable() returning 'false' even though the www user is in the group that owns the file, but the PHP 5 server is returning 'true.'
darek at fauxaddress dot com
31-Jan-2006 08:27
It appears that is_writable() does not check full permissions of a file to determine whether the current user can write to it.  For example, with Apache running as user 'www', and a member of the group 'wheel', is_writable() returns false on a file like

-rwxrwxr-x           root         wheel          /etc/some.file
JimmyNighthawk
11-Sep-2005 11:02
Regarding you might recognize your files on your web contructed by your PHP-scripts are grouped as NOBODY you can avoid this problem by setting up an FTP-Connection ("ftp_connect", "ftp_raw", etc.) and use methods like "ftp_fput" to create these [instead of giving out rights so you can use the usual "unsecure" way]. This will give the files created not the GROUP NOBODY - it will give out the GROUP your FTP-Connection via your FTP-Program uses, too.

Furthermore you might want to hash the password for the FTP-Connection - then check out:
http://dev.mysql.com/doc/mysql/en/Password_hashing.html
claude dot paroz at ne dot ch
06-Apr-2004 01:28
Under Windows, it only returns the read-only attribute status, not the actual permissions (ACL).
See http://bugs.php.net/bug.php?id=27609
agrenier at assertex dot com
02-Apr-2004 01:56
This file_write() function will give $filename the write permission before writing $content to it.

Note that many servers do not allow file permissions to be changed by the PHP user.

<?php
    function file_write($filename, &$content) {
        if (!is_writable($filename)) {
            if (!chmod($filename, 0666)) {
                 echo "Cannot change the mode of file ($filename)";
                 exit;
            };
        }
        if (!$fp = @fopen($filename, "w")) {
            echo "Cannot open file ($filename)";
            exit;
        }
        if (fwrite($fp, $content) === FALSE) {
            echo "Cannot write to file ($filename)";
            exit;
        }
        if (!fclose($fp)) {
            echo "Cannot close file ($filename)";
            exit;
        }
    }
?>

is_writeable> <is_uploaded_file
Last updated: Fri, 03 Feb 2012