realpath

Because realpath() does not work on files that do notexist, I wrote a function that does.It replaces (consecutive) occurences of / and \\ withwhatever 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) orposition -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. :)

Needed a method to normalize a virtual path that could handle .. references that go beyond the initial folder reference. So I created the following.<?phpfunction 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/filenameto ../../one/three/filename

<?phpnamespace MockingMagician\Organic\Helper;class Path{    /**     * There is a method that deal with Sven Arduwie proposal https://www.php.net/manual/en/function.realpath.php#84012     * And runeimp at gmail dot com proposal https://www.php.net/manual/en/function.realpath.php#112367     * @param string $path     * @return string     */    public static function getAbsolute(string $path): string    {        // Cleaning path regarding OS        $path = mb_ereg_replace('\\\\|/', DIRECTORY_SEPARATOR, $path, 'msr');        // Check if path start with a separator (UNIX)        $startWithSeparator = $path[0] === DIRECTORY_SEPARATOR;        // Check if start with drive letter        preg_match('/^[a-z]:/', $path, $matches);        $startWithLetterDir = isset($matches[0]) ? $matches[0] : false;        // Get and filter empty sub paths        $subPaths = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'mb_strlen');        $absolutes = [];        foreach ($subPaths as $subPath) {            if ('.' === $subPath) {                continue;            }            // if $startWithSeparator is false            // and $startWithLetterDir            // and (absolutes is empty or all previous values are ..)            // save absolute cause that's a relative and we can't deal with that and just forget that we want go up            if ('..' === $subPath                && !$startWithSeparator                && !$startWithLetterDir                && empty(array_filter($absolutes, function ($value) { return !('..' === $value); }))            ) {                $absolutes[] = $subPath;                continue;            }            if ('..' === $subPath) {                array_pop($absolutes);                continue;            }            $absolutes[] = $subPath;        }        return            (($startWithSeparator ? DIRECTORY_SEPARATOR : $startWithLetterDir) ?                $startWithLetterDir.DIRECTORY_SEPARATOR : ''            ).implode(DIRECTORY_SEPARATOR, $absolutes);    }    /**     * Examples     *     * echo Path::getAbsolute('/one/two/../two/./three/../../two');            =>    /one/two     * echo Path::getAbsolute('../one/two/../two/./three/../../two');          =>    ../one/two     * echo Path::getAbsolute('../.././../one/two/../two/./three/../../two');  =>    ../../../one/two     * echo Path::getAbsolute('../././../one/two/../two/./three/../../two');   =>    ../../one/two     * echo Path::getAbsolute('/../one/two/../two/./three/../../two');         =>    /one/two     * echo Path::getAbsolute('/../../one/two/../two/./three/../../two');      =>    /one/two     * echo Path::getAbsolute('c:\.\..\one\two\..\two\.\three\..\..\two');     =>    c:/one/two     *     */}

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).

Here's a function to canonicalize a URL containing relative paths. Ran into the problem when pulling links from a remote page.<?phpfunction 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?>

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

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).

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\\"

It should probably be expressly noted that tilde expansion is not performed by realpath.

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 :<?phpvar_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 :<?phpvar_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"?>

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 $to are on different drives.<?phpfunction relativePath($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);}?>

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.

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.

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.BATSame 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.

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.

Sven Arduwie answer is not tested and does not replicate the behavior of realpath but is a close solution.This has been unit tested to be as close to realpath as possible but without the path having to actually exist in the system.This takes relative paths and realizes them properly based on actual current working directory, but everything can be virtual. eg.  "../someVirtualDir/./virtualFile.jpg"<?php    public static function virtualpath($path): string    {        $path = str_replace(['/', '\\'], DIRECTORY_SEPARATOR, $path);        $len = strlen($path);        $relative = strpos($path, DIRECTORY_SEPARATOR);        if (!$len || ($len > 0 && $path[0] == '.') || $relative !== 0) {            $path = getcwd() . DIRECTORY_SEPARATOR . $path;        }        $parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');        $absolutes = [];        foreach ($parts as $part) {            if ('.' == $part) {                continue;            }            if ('..' == $part) {                array_pop($absolutes);            } else {                $absolutes[] = $part;            }        }        return DIRECTORY_SEPARATOR . implode(DIRECTORY_SEPARATOR, $absolutes);    }?>

Be noticed that, one of the reasons of realtpath retuning false can be if the path does not exist, or it has permission issues, or even if security modules of your operating system (let's say, SELinux for example) avoids you checking the path.If you're like me and you had a not very good time checking why realpath retuns false, please check these points first.