realpath

(PHP 4, PHP 5, PHP 7)

realpathZwraca kanoniczną ścieżkę abslutną

Opis

realpath ( string $ścieżka ) : string

realpath() rozszerza wszystkie łącza symboliczne i rozwiązuje odwołania do '/./', '/../' i dodatkowych znaków '/' w wejściowym parametrze ścieżka i zwraca kanoniczną ścieżkę absolutną.

Parametry

ścieżka

Sprawdzana ścieżka.

Informacja:

Podczas gdy ścieżka musi być określona, wartość może być pusta lub ustawiona na NULL W tym wypadku wartość jest interpretowana jako aktualny katalog.

Zwracane wartości

Zwraca kanoniczną ścieżkę absolutną w wypadku powodzenia. Wynikowa ścieżka nie będzie miała symbolicznych linków ani znaków '/./' lub '/../'. Końcowe ograniczniki, takie jak \ czy /, też są usuwane.

realpath() zwraca FALSE w wypadku błędu, np. gdy plik nie istnieje.

Informacja:

Uruchamiany skrypt musi mieć prawa do uruchamiania we wszystkich katalogach w hierarchii, inaczej realpath() zwróci FALSE.

Informacja:

W systemach plików niewrażliwych na wielkość znaków realpath() może lecz nie musi normalizować wielkości znaków.

Informacja: Ponieważ typ integer stosowany w PHP zawiera bit znaku a wiele platform stosuje 32-bitowe liczby całkowite, niektóre funkcje obsługi systemów plików mogą zwracać nieprzewidzane wyniki dla plików większych niż 2GB.

Rejestr zmian

Wersja Opis
5.3.0 Do tego wydania, jeżeli tylko ostatni komponent ścieżki nie istniał, realpath() nie kończyła się niepowodzeniem na systemach *BSD. realpath() od teraz zwraca błąd w takim wypadku.
5.2.1 Przed tą wersją funkcja realpath() zwracała FALSE jeśli ścieżka była pustym stringiem lub NULL.

Przykłady

Przykład #1 Przykład użycia realpath()

<?php
chdir
('/var/www/');
echo 
realpath('./../../etc/passwd') . PHP_EOL;
echo 
realpath('/tmp/') . PHP_EOL;
?>

Powyższy przykład wyświetli:

/etc/passwd
/tmp

Przykład #2 realpath() pod Windows

Pod systemem Windows realpath() zmieni ścieżki w stylu Unix na styl Windows.

<?php
echo realpath('/windows/system32');

echo 
realpath('C:\Program Files\\');
?>

Powyższy przykład wyświetli:

C:\WINDOWS\System32
C:\Program Files

Zobacz też:

  • basename() - Zwraca nazwę pliku, będącego składową ścieżki
  • dirname() - Zwraca nazwę katalogu, będącego składową ścieżki
  • pathinfo() - Zwraca informacje o ścieżce do pliku

add a note add a note

User Contributed Notes 14 notes

up
54
Sven Arduwie
12 years ago
Because realpath() does not work on files that do not
exist, I wrote a function that does.
It replaces (consecutive) occurences of / and \\ with
whatever is in DIRECTORY_SEPARATOR, and processes /. and /.. fine.
Paths returned by get_absolute_path() contain no
(back)slash at position 0 (beginning of the string) or
position -1 (ending)
<?php
   
function get_absolute_path($path) {
       
$path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);
       
$parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
       
$absolutes = array();
        foreach (
$parts as $part) {
            if (
'.' == $part) continue;
            if (
'..' == $part) {
               
array_pop($absolutes);
            } else {
               
$absolutes[] = $part;
            }
        }
        return
implode(DIRECTORY_SEPARATOR, $absolutes);
    }
?>

A test:
<?php
    var_dump
(get_absolute_path('this/is/../a/./test/.///is'));
?>
Returns: string(14) "this/a/test/is"

As you can so, it also produces Yoda-speak. :)
up
40
runeimp at gmail dot com
7 years ago
Needed a method to normalize a virtual path that could handle .. references that go beyond the initial folder reference. So I created the following.
<?php

function normalizePath($path)
{
   
$parts = array();// Array to build a new path from the good parts
   
$path = str_replace('\\', '/', $path);// Replace backslashes with forwardslashes
   
$path = preg_replace('/\/+/', '/', $path);// Combine multiple slashes into a single slash
   
$segments = explode('/', $path);// Collect path segments
   
$test = '';// Initialize testing variable
   
foreach($segments as $segment)
    {
        if(
$segment != '.')
        {
           
$test = array_pop($parts);
            if(
is_null($test))
               
$parts[] = $segment;
            else if(
$segment == '..')
            {
                if(
$test == '..')
                   
$parts[] = $test;

                if(
$test == '..' || $test == '')
                   
$parts[] = $segment;
            }
            else
            {
               
$parts[] = $test;
               
$parts[] = $segment;
            }
        }
    }
    return
implode('/', $parts);
}
?>

Will convert /path/to/test/.././..//..///..///../one/two/../three/filename
to ../../one/three/filename
up
23
Anonymous
8 years ago
Note: If you use this to check if a file exists, it's path will be cached, and returns true even if the file is removed (use file_exists instead).
up
14
David Beck
13 years ago
Here's a function to canonicalize a URL containing relative paths. Ran into the problem when pulling links from a remote page.

<?php

function canonicalize($address)
{
   
$address = explode('/', $address);
   
$keys = array_keys($address, '..');

    foreach(
$keys AS $keypos => $key)
    {
       
array_splice($address, $key - ($keypos * 2 + 1), 2);
    }

   
$address = implode('/', $address);
   
$address = str_replace('./', '', $address);
}

$url = 'http://www.example.com/something/../else';
echo
canonicalize($url); //http://www.example.com/else

?>
up
6
https://stackoverflow.com/users/1397947/
3 years ago
It should probably be expressly noted that tilde expansion is not performed by realpath.
up
7
Jrg Wagner
10 years ago
Please be aware that this function does NOT always strip a trailing slash!:

LINUX (tested with PHP 5.2.11):
---
realpath('.')
: string = "/myhttpdfolder"
realpath('./')
: string = "/myhttpdfolder"
realpath('fileadmin')
: string = "/myhttpdfolder/fileadmin"
realpath('fileadmin/')
: string = "/myhttpdfolder/fileadmin"

WINDOWS (tested with PHP 5.2.5):
---
realpath('.')
: string = "C:\\myhttpdfolder"
realpath('./')
: string = "C:\\myhttpdfolder\\"
realpath('fileadmin')
: string = "C:\\myhttpdfolder\\fileadmin"
realpath('fileadmin/')
: string = "C:\\myhttpdfolder\\fileadmin\\"
up
5
pulstar at ig dot com dot br
15 years ago
Sometimes you may need to refer to the absolute path of a file in your website instead of a relative path, but the realpath() function returns the path relative to the server's filesystem, not a path relative to your website root directory.

For example, realpath() may return something like this:

/home/yoursite/public_html/dir1/file.ext

You can't use this in an HTML document, because the web server will not find the file. To do so, you can use:

<?php

function htmlpath($relative_path) {
   
$realpath=realpath($relative_path);
   
$htmlpath=str_replace($_SERVER['DOCUMENT_ROOT'],'',$realpath);
    return
$htmlpath;
}

echo
'<img src="',htmlpath('../../relative/path/to/file.ext'),'" border=1>';

?>

It will return something like:

<img src="/dir1/relative/path/to/file.ext" border=1>
up
8
imagiro
9 years ago
Here is a small and handy method to calculate the relative path from $from to $to. Note: On Windows it does not work when $from and $to are on different drives.

<?php
function relativePath($from, $to, $ps = DIRECTORY_SEPARATOR)
{
 
$arFrom = explode($ps, rtrim($from, $ps));
 
$arTo = explode($ps, rtrim($to, $ps));
  while(
count($arFrom) && count($arTo) && ($arFrom[0] == $arTo[0]))
  {
   
array_shift($arFrom);
   
array_shift($arTo);
  }
  return
str_pad("", count($arFrom) * 3, '..'.$ps).implode($ps, $arTo);
}
?>
up
4
Vincent Par
5 years ago
Beware of relative symbolic links like this one (ext4 file system on Ubuntu) :

    vincent@vincent:~/Bureau/dirscan$ readlink sandbox/roulant/voiture/cabriolet/ln-loop-relative
    ../..

In this case, realpath may return false :

<?php
var_dump
(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative'));
// => string(44) "/home/vincent/Bureau/dirscan/sandbox/roulant"
var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative/moto'));
// => bool(false)
?>

But you can fix it by clearing the realpath cache, this way :

<?php
var_dump
(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative'));
clearstatcache(true);
var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative/moto'));
// => string(49) "/home/vincent/Bureau/dirscan/sandbox/roulant/moto"
?>
up
2
eion at robbmob dot com
4 years ago
Be aware that realpath() doesn't work with hidden Windows UNC paths, eg  \\servername\share$\folder\blah.txt but other PHP file-functions can access that file fine.
up
5
php at keith tyler dot com
9 years ago
Note that under Windows, a slash-rooted path will resolve on the local drive, and *not* necessarily C:\.

For example:

M:\>php -r "print realpath('/AUTOEXEC.BAT');"
[prints nothing, because there is no M:\AUTOEXEC.BAT]

But:

M:\>C:
C:\>php -r "print realpath('/AUTOEXEC.BAT');"
C:\AUTOEXEC.BAT

Same script, different response depending on current drive.

I'm inclined to argue that this function *should* use the value of %SystemDrive% as the "slash root" base.
up
1
Lars Scheithauer <l dot scheithauer at gmx dot de>
15 years ago
This function is also nice to test for security-breaches. You can forbid the script to access files below a certain directory to prevent "../../../etc/shadow" and similar attacks:

<?php

// declare the basic directory for security reasons
// Please do NOT attach a "/"-suffix !
$basedir = '/var/www/cgi-bin/scriptfolder';

// compare the entered path with the basedir
$path_parts = pathinfo($_REQUEST['file_to_get']);
if (
realpath($path_parts['dirname']) != $basedir) {
   
/* appropriate action against crack-attempt*/
   
die ('coding good - h4x1ng bad!');
}

?>

The url "script.php?file_to_get=../../../etc/shadow" will now result in an error.
up
1
Leonard Challis
7 years ago
When using realpath (and similar functions) remember that PHP will take in to account open_basedir restrictions. So, if you do something like:

<?php
// test.php in httpdocs folder
$path = realpath(dirname(__FILE__) . '/../application');
?>

where your open_basedir setting is set to the httpdocs folder and tmp, this will return false. You must set it to the level above (or off) for this to work.
up
1
plamen at dragiyski dot org
1 year ago
realpath() is just a system/library call to actual realpath() function supported by OS. It does not work on a path as a string, but also resolves symlinks. The resulting path might significantly differs from the input even when absolute path is given. No function in this notes resolves that.

The suggestion on the realpath man page is to look for an existing parent directory. Here is an example:
<?php
   
function resolvePath($path) {
        if(
DIRECTORY_SEPARATOR !== '/') {
           
$path = str_replace(DIRECTORY_SEPARATOR, '/', $path);
        }
       
$search = explode('/', $path);
       
$search = array_filter($search, function($part) {
            return
$part !== '.';
        });
       
$append = array();
       
$match = false;
        while(
count($search) > 0) {
           
$match = realpath(implode('/', $search));
            if(
$match !== false) {
                break;
            }
           
array_unshift($append, array_pop($search));
        };
        if(
$match === false) {
           
$match = getcwd();
        }
        if(
count($append) > 0) {
           
$match .= DIRECTORY_SEPARATOR . implode(DIRECTORY_SEPARATOR, $append);
        }
        return
$match;
    }
?>

The result will retrieve absolute path for non-existing relative path. Even if a path does not exists, there should be existing directory somewhere, for which the realpath could be obtained. If this is not within the relative path (i.e. even current working directory does not exists), getcwd() will retrieve absolute path, so some absolute path is returned (although in that case the PHP process could have huge problems).
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