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(PHP 4, PHP 5, PHP 7, PHP 8)
dl — Loads a PHP extension at runtime
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 SAPIs, and the CGI SAPI when run from the command line.
extension_filenameThis 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.
Unix - If not explicitly set in the php.ini, the default extension directory depends on
--enable-debug
or not
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)
<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.
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.
Example #1 dl() examples
<?php
// 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);
}
?>Note:
dl() is case sensitive on Unix platforms.
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');
?><?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 = $loadedExtensions[ sizeof( $loadedExtensions ) - 1 ];
//lastly, we return the extension name
return $thisExtName;
}//end dl_local()
?>