is_writable

(PHP 4, PHP 5, PHP 7, PHP 8)

is_writable — Indique si un fichier est accessible en écriture

Description

is_writable(string $filename): bool

retourne true si filename existe et est accessible en écriture. L'argument peut être le nom d'un dossier, vous permettant ainsi de vérifier si le dossier est accessible en écriture.

N'oubliez pas que PHP accède aux fichiers avec les mêmes autorisations que l'utilisateur qui fait tourner le serveur web (souvent, c'est 'nobody', personne).

Liste de paramètres

filename: Le nom du fichier à vérifier.

Valeurs de retour

Retourne true si le fichier filename existe et est accessible en écriture.

Erreurs / Exceptions

En cas d'échec, une alerte de type E_WARNING sera émise.

Exemples

Exemple #1 Exemple avec is_writable()

<?php
$filename = 'test.txt';
if (is_writable($filename)) {
    echo 'Le fichier est accessible en écriture.';
} else {
    echo 'Le fichier n\'est pas accessible en écriture !';
}
?>

Notes

Note: Les résultats de cette fonction sont mis en cache. Voyez la fonction clearstatcache() pour plus de détails.

Astuce

À partir de PHP 5.0.0, cette fonction peut aussi être utilisée avec quelques protocoles url. Lisez Liste des protocoles et des gestionnaires supportés pour connaître les protocoles supportant la famille de fonctionnalités de stat().

Voir aussi

is_readable() - Indique si un fichier existe et est accessible en lecture
file_exists() - Vérifie si un fichier ou un dossier existe
fwrite() - Écrit un fichier en mode binaire

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User Contributed Notes 15 notes

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helvete at bahno dot net ¶

7 years ago


Be warned, that is_writable returns false for non-existent files, although they can be written to the queried path.

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starrychloe at yahoo dot com ¶

16 years ago


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

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darek at fauxaddress dot com ¶

18 years ago


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

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arikan134 at gmail dot com ¶

8 years ago


Check director is writable recursively. to return true, all of directory contents  must be writable

<?php
function is_writable_r($dir) {
    if (is_dir($dir)) {
        if(is_writable($dir)){
            $objects = scandir($dir);
            foreach ($objects as $object) {
                if ($object != "." && $object != "..") {
                    if (!is_writable_r($dir."/".$object)) return false;
                    else continue;
                }
            }    
            return true;    
        }else{
            return false;
        }
        
    }else if(file_exists($dir)){
        return (is_writable($dir));
        
    }
}

?>

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agrenier at assertex dot com ¶

20 years ago


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;
        }
    } 
?>

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JimmyNighthawk ¶

19 years ago


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

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gr ¶

14 years ago


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;
?>

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develop at radon-software dot net ¶

2 years ago


This function returns always false on windows, when you check an network drive.

See PHP Bug https://bugs.php.net/bug.php?id=68926
See https://stackoverflow.com/q/54904676

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greg at gregwhitescarver dotcalm ¶

18 years ago


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.'

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-1

legolas558 d0t users dot sf dot net ¶

17 years ago


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;
}
?>

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-4

legolas558 dot sourceforge comma net ¶

18 years ago


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

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-9

yury dot gugnin at gmail dot com ¶

10 years ago


function is_writable('ftp://user.....') always return false. I can create/delete files, but can check is writable. Is this bug or php feature :)?

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-3

shkkmo at gmail dot com ¶

9 years ago


I'd like to also clarify a point on this. Even if you see 777 permissions for the directly, you may need to check your ACL, since your server's group might not have write permissions there.

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-3

samuel dot zallocco at univaq dot it ¶

10 years ago


Check if a directory is writable. Work also on mounted SMB shares:

function isWritablePath($home, $xpath) {
    $isOK = false;
    $path = trim($xpath);
    if ( ($path!="") && (strpos($path,$home)!==false)  && is_dir($path) && is_writable($path) ) {
        $tmpfile = "mPC_".uniqid(mt_rand()).'.writable';
        $fullpathname = str_replace('//','/',$path."/".$tmpfile);
        $fp = @fopen($fullpathname,"w");
        if ($fp !== false) {
            $isOK = true;
        }
        @fclose($fp);
        @unlink($fullpathname);
    }
    return $isOK;
    
}

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-5

claude dot paroz at ne dot ch ¶

20 years ago


Under Windows, it only returns the read-only attribute status, not the actual permissions (ACL).
See http://bugs.php.net/bug.php?id=27609

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