dl() function

faheemhameed

Hi there,

I have my php pages hosted with a web host. I have used gd image library functions in my code to create thumbnail images. Unfortunately the web host is not willing to install the gd library in their server. So I need a way to dynamically load the extension inside the code.

How the dl() function works?. Can this function be used to load an extension file which is stored in a folder within my website folder.

Is this possible?

The web server running Red Hat Linux + PHP + My SQL

Your help would be highly appreciated.

Thanks
Hameed

jsim

To load extension from your web folder you need to know full path to extension. You can obtain it through

echo getcwd();

Then using full path you can load you extension with dl() parameter like this:

dl('../../../../../../../../../../path_to_your_web_folder/extension.so');

Hope it helps.

faheemhameed

Hi jsim,

Thanks for you reply.

I tried the following in my windows 2000 local server.

I disabled the gd2 by changing php.ini entry
;extension=php_gd2.dll

extension_dir = "./extensions"
enable_dl = On

============================================================
In my test.php I used the following code

$ExtensionPath = getcwd();
dl( $ExtensionPath . "\temp\" . "php_gd2.dll");
//where in "temp" folder within the webserver root folder I have copied gd2 library

$destImage = imageCreateTrueColor(200, 200) or die ("Cannot Initialize new GD image stream");
// the above function call is to check whether the gd library is really working

============================================================

I get the following error:

Warning: dl(): Unable to load dynamic library './extensions\d:\inetpub\apache\hkics\temp\php_gd2.dll' - The specified module could not be found. in d:\inetpub\apache\hkics\test.php on line 11

Fatal error: Call to undefined function: imagecreatetruecolor() in d:\inetpub\apache\hkics\test.php on line 19

============================================================

I think the it looks for the library file inside the folder used in the extension_dir settings.

Please share your ideas.

Thanks a lot.

Hameed

jsim

dl() function cannot take absolute path to the extension.
You can only pass to it name of the extension file and relative path (optionally). Lets say that in php.ini you has
extension_dir = "./extensions"

And ANY parameter passed to dl() will be added to the end of "extension_dir" string. Si, passing full path to the dl() will be treated as ./extensions/full_path

If you read my previous post more carefully you'll see that there is a few '../' chars before full_path string. It's needed to locate you extension outside php's extension dir. So, using it you'll get:
./extensions/../../../../../../full_path/extension.so

This trick will always works on linux, but on Windows you have some restrictions: using this trick you cannot change drive letter.
So for use it on Windows you need installed php and www root on the same drive letter. But you've asked about Linux 😉

Shrike

I had a play with GD yesterday, to set it up on WinXP I used

if(!extension_loaded("gd")){
  !dl("extensions/gd.dll")
    and die("GD lib not loaded");
}

dl() should tell you the path it's looking in so it should be easy enough to debug.

This loaded GD in Windows, and also worked on my linux host presumably because GD was preloaded 🙂