dl

(PHP 4, PHP 5)

dlLoads a PHP extension at runtime

Description

bool dl ( string $library )

Loads the PHP extension given by the parameter library.

Use extension_loaded() to test whether a given extension is already available or not. This works on both built-in extensions and dynamically loaded ones (either through php.ini or dl()).

Warning

This function has been removed from some SAPIs in PHP 5.3.

Parameters

library

This parameter is only the filename of the extension to load which also depends on your platform. For example, the sockets extension (if compiled as a shared module, not the default!) would be called sockets.so on Unix platforms whereas it is called php_sockets.dll on the Windows platform.

The directory where the extension is loaded from depends on your platform:

Windows - If not explicitly set in the php.ini, the extension is loaded from C:\php4\extensions\ (PHP 4) or C:\php5\ (PHP 5) by default.

Unix - If not explicitly set in the php.ini, the default extension directory depends on

  • whether PHP has been built with --enable-debug or not
  • whether PHP has been built with (experimental) ZTS (Zend Thread Safety) support or not
  • the current internal ZEND_MODULE_API_NO (Zend internal module API number, which is basically the date on which a major module API change happened, e.g. 20010901)
Taking into account the above, the directory then defaults to <install-dir>/lib/php/extensions/ <debug-or-not>-<zts-or-not>-ZEND_MODULE_API_NO, e.g. /usr/local/php/lib/php/extensions/debug-non-zts-20010901 or /usr/local/php/lib/php/extensions/no-debug-zts-20010901.

Return Values

Returns TRUE on success or FALSE on failure. If the functionality of loading modules is not available or has been disabled (either by setting enable_dl off or by enabling safe mode in php.ini) an E_ERROR is emitted and execution is stopped. If dl() fails because the specified library couldn't be loaded, in addition to FALSE an E_WARNING message is emitted.

Examples

Example #1 dl() examples

<?php
// Example loading an extension based on OS
if (!extension_loaded('sqlite')) {
    if (
strtoupper(substr(PHP_OS03)) === 'WIN') {
        
dl('php_sqlite.dll');
    } else {
        
dl('sqlite.so');
    }
}

// Or, the PHP_SHLIB_SUFFIX constant is available as of PHP 4.3.0
if (!extension_loaded('sqlite')) {
    
$prefix = (PHP_SHLIB_SUFFIX === 'dll') ? 'php_' '';
    
dl($prefix 'sqlite.' PHP_SHLIB_SUFFIX);
}
?>

Changelog

Version Description
5.3.0 dl() is now disabled in some SAPIs due to stability issues. The only SAPIs that allow dl() are CLI and Embed. Use the Extension Loading Directives instead.

Notes

Note:

dl() is not supported when PHP is built with ZTS support. Use the Extension Loading Directives instead.

Note:

dl() is case sensitive on Unix platforms.

Note: This function is disabled when PHP is running in safe mode.

See Also

Коментарии

If you need to load an extension from the CURRENT local directory because you do not have privelages to place the extension in your servers PHP extensions directory, this function i wrote may be of use to you

<?php
/*
    Function: dl_local()
    Reference: http://us2.php.net/manual/en/function.dl.php
    Author: Brendon Crawford <endofyourself |AT| yahoo>
    Usage: dl_local( "mylib.so" );
    Returns: Extension Name (NOT the extension filename however)
    NOTE:
        This function can be used when you need to load a PHP extension (module,shared object,etc..),
        but you do not have sufficient privelages to place the extension in the proper directory where it can be loaded. This function
        will load the extension from the CURRENT WORKING DIRECTORY only.
        If you need to see which functions are available within a certain extension,
        use "get_extension_funcs()". Documentation for this can be found at
        "http://us2.php.net/manual/en/function.get-extension-funcs.php".
*/

function dl_local$extensionFile ) {
   
//make sure that we are ABLE to load libraries
   
if( !(bool)ini_get"enable_dl" ) || (bool)ini_get"safe_mode" ) ) {
     die( 
"dh_local(): Loading extensions is not permitted.\n" );
    }

     
//check to make sure the file exists
   
if( !file_exists$extensionFile ) ) {
     die( 
"dl_local(): File '$extensionFile' does not exist.\n" );
    }
   
   
//check the file permissions
   
if( !is_executable$extensionFile ) ) {
     die( 
"dl_local(): File '$extensionFile' is not executable.\n" );
    }

 
//we figure out the path
 
$currentDir getcwd() . "/";
 
$currentExtPath ini_get"extension_dir" );
 
$subDirs preg_match_all"/\//" $currentExtPath $matches );
 unset( 
$matches );
 
     
//lets make sure we extracted a valid extension path
   
if( !(bool)$subDirs ) {
     die( 
"dl_local(): Could not determine a valid extension path [extension_dir].\n" );
    }
 
 
$extPathLastChar strlen$currentExtPath ) - 1;
 
    if( 
$extPathLastChar == strrpos$currentExtPath "/" ) ) {
     
$subDirs--;
    }

 
$backDirStr ""
     for( 
$i 1$i <= $subDirs$i++ ) {
     
$backDirStr .= "..";
        if( 
$i != $subDirs ) {
         
$backDirStr .= "/";
        }
    }

 
//construct the final path to load
 
$finalExtPath $backDirStr $currentDir $extensionFile;
 
   
//now we execute dl() to actually load the module
     
if( !dl$finalExtPath ) ) {
     die();
    }

 
//if the module was loaded correctly, we must bow grab the module name
 
$loadedExtensions get_loaded_extensions();
 
$thisExtName $loadedExtensionssizeof$loadedExtensions ) - ];
 
 
//lastly, we return the extension name
 
return $thisExtName;

}
//end dl_local()

?>
2003-10-18 07:12:50
http://php5.kiev.ua/manual/ru/function.dl.html
<?php

function dl_local$extensionFile ) {
   
//make sure that we are ABLE to load libraries
   
if( !(bool)ini_get"enable_dl" ) || (bool)ini_get"safe_mode" ) ) {
     die( 
"dh_local(): Loading extensions is not permitted.\n" );
   }

     
//check to make sure the file exists
   
if( !file_exists$extensionFile ) ) {
     die( 
"dl_local(): File '$extensionFile' does not exist.\n" );
   }
   
   
//check the file permissions
   
if( !is_executable$extensionFile ) ) {
     die( 
"dl_local(): File '$extensionFile' is not executable.\n" );
   }

 
//we figure out the path
 
$currentDir getcwd() . "/";
 
$currentExtPath ini_get"extension_dir" );
 
$subDirs preg_match_all"/\//" $currentExtPath $matches );
 unset( 
$matches );
 
     
//lets make sure we extracted a valid extension path
   
if( !(bool)$subDirs ) {
     die( 
"dl_local(): Could not determine a valid extension path [extension_dir].\n" );
   }
 
 
$extPathLastChar strlen$currentExtPath ) - 1;
 
   if( 
$extPathLastChar == strrpos$currentExtPath "/" ) ) {
     
$subDirs--;
   }

 
$backDirStr ""
     for( 
$i 1$i <= $subDirs$i++ ) {
     
$backDirStr .= "..";
       if( 
$i != $subDirs ) {
         
$backDirStr .= "/";
       }
   }

 
//construct the final path to load
 
$finalExtPath $backDirStr $currentDir $extensionFile;
 
   
//now we execute dl() to actually load the module
     
if( !dl$finalExtPath ) ) {
     die();
   }

 
//if the module was loaded correctly, we must bow grab the module name
 
$loadedExtensions get_loaded_extensions();
 
$thisExtName $loadedExtensionssizeof$loadedExtensions ) - ];
 
 
//lastly, we return the extension name
 
return $thisExtName;

}
//end dl_local()

?>
2005-12-06 13:13:44
http://php5.kiev.ua/manual/ru/function.dl.html
dl is awkward because the filename format is OS-dependent and because it can complain if the extension is already loaded. This wrapper function fixes that:

<?php

function load_lib($n$f null) {
    return 
extension_loaded($n) or dl(((PHP_SHLIB_SUFFIX === 'dll') ? 'php_' '') . ($f $f $n) . '.' PHP_SHLIB_SUFFIX);
}

?>

Examples:

<?php

// ensure we have SSL and MySQL support
load_lib('openssl');
load_lib('mysql');

// a rare few extensions have a different filename to their extension name, such as the image (gd) library, so we specify them like this:
load_lib('gd''gd2');

?>
2009-01-29 02:34:18
http://php5.kiev.ua/manual/ru/function.dl.html
Like with eval(), the only correct way to use dl() is to not use it.
Test if a function(s) you intend to use are available.
If not, complain to the user or implement a workaround.
Not to mention dl() issues in a multithreading environment.
2016-09-29 15:17:39
http://php5.kiev.ua/manual/ru/function.dl.html

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