Php dynamic extension loading

dl — Loads a PHP extension at runtime

Description

Loads the PHP extension given by the parameter extension_filename .

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() ).

This function is only available for the CLI and embed SAPI s, and the CGI SAPI when run from the command line.

Parameters

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:\php5\ by default.

whether PHP has been built with —enable-debug or not
whether PHP has been built with 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 )

Return Values

Returns true on success or false on failure. If the functionality of loading modules is not available or has been disabled (by setting enable_dl off 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

// Example loading an extension based on OS
if (! extension_loaded ( ‘sqlite’ )) if ( strtoupper ( substr ( PHP_OS , 0 , 3 )) === ‘WIN’ ) dl ( ‘php_sqlite.dll’ );
> else dl ( ‘sqlite.so’ );
>
>

// Or using PHP_SHLIB_SUFFIX constant
if (! extension_loaded ( ‘sqlite’ )) $prefix = ( PHP_SHLIB_SUFFIX === ‘dll’ ) ? ‘php_’ : » ;
dl ( $prefix . ‘sqlite.’ . PHP_SHLIB_SUFFIX );
>
?>

Notes

Note:

dl() is case sensitive on Unix platforms.

User Contributed Notes 4 notes

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:

function load_lib ( $n , $f = null ) return extension_loaded ( $n ) or dl ((( PHP_SHLIB_SUFFIX === ‘dll’ ) ? ‘php_’ : » ) . ( $f ? $f : $n ) . ‘.’ . PHP_SHLIB_SUFFIX );
>

// 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’ );

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 —;
>

//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 = $loadedExtensions [ sizeof ( $loadedExtensions ) — 1 ];

//lastly, we return the extension name
return $thisExtName ;

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.

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

/*
Function: dl_local()
Reference: http://us2.php.net/manual/en/function.dl.php
Author: Brendon Crawford
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 —;
>

//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 = $loadedExtensions [ sizeof ( $loadedExtensions ) — 1 ];

//lastly, we return the extension name
return $thisExtName ;

PHP Options/Info Functions

assert_options
assert
cli_get_process_title
cli_set_process_title
dl
extension_loaded
gc_collect_cycles
gc_disable
gc_enable
gc_enabled
gc_mem_caches
gc_status
get_cfg_var
get_current_user
get_defined_constants
get_extension_funcs
get_include_path
get_included_files
get_loaded_extensions
get_required_files
get_resources
getenv
getlastmod
getmygid
getmyinode
getmypid
getmyuid
getopt
getrusage
ini_alter
ini_get_all
ini_get
ini_parse_quantity
ini_restore
ini_set
memory_get_peak_usage
memory_get_usage
memory_reset_peak_usage
php_ini_loaded_file
php_ini_scanned_files
php_sapi_name
php_uname
phpcredits
phpinfo
phpversion
putenv
set_include_path
set_time_limit
sys_get_temp_dir
version_compare
zend_thread_id
zend_version

get_magic_quotes_gpc
get_magic_quotes_runtime
restore_include_path

Источник

Php dynamic extension loading

dl — Loads a PHP extension at runtime

Описание

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() ).

This function has been removed from some SAPI’s in PHP 5.3.

Список параметров

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\ (PHP4) or C:\php5\ (PHP5) by default.

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)

Возвращаемые значения

Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки. If the functionality of loading modules is not available or has been disabled (either by setting enable_dl off or by enabling безопасный режим 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.

Примеры

Пример #1 dl() examples

// 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 );
>
?>

Список изменений

Версия	Описание
5.3.0	dl() is now disabled in some SAPI’s due to stability issues. The only SAPI’s that allow dl() are: CLI, CGI and Embed. Use the Extension Loading Directives instead.

Примечания

Замечание:

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

Замечание:

dl() is case sensitive on Unix platforms.

Смотрите также

Источник

Php dynamic extension loading

Dynamic PHP Extensions Not Loading

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Php dynamic extension loading

Description

Parameters

Return Values

Examples

Notes

See Also

User Contributed Notes 4 notes

Php dynamic extension loading

Описание

Список параметров

Возвращаемые значения

Примеры

Список изменений

Примечания

Смотрите также