How to properly use a .dylib in a plugin on OSX?

[Arie Stavchansky]

Hello All,

So after using the much appreciated help here on the forums, I was successful at loading a third-party DLL that I needed to use in my plugin on Windows.  Now, I'm moving onto OSX and have a .dylib file that is effectively the equivalent of the DLL in OSX.  My question is how do I properly load the .dylib on OSX for my plugin to work within AE?

Many thanks for your time and help!

Best,
Arie

[Guest]

Hi Arie,

well, it depends on how much you know already and where you are having problems. 🙂

A .dylib is basically nothing more than a renamed .so (shared object) object file from the Linux world

The equivalent command for "LoadLibrary" on MacOS is "dlopen", and you can access function pointers/symbols with "dlsym", and instead of "FreeLibrary" you use "dlclose".

Check these links for some info:

Dynamic loading - Wikipedia, the free encyclopedia

OS X ABI Dynamic Loader Reference‌

http://stackoverflow.com/questions/2339679/what-are-the-differences-between-so-and-dylib-on-osx

[Arie Stavchansky]

But how do you reference the .dylib file?  Do we just include it in the bundle of the plugin and reference it somehow from there?

[Guest]

That is the same situation as on Windows with a Dll

You can deploy the dylib as part of your bundle / plugin (which is a folder anyway) or in any other common folder, then use the path function from the sdk that I posted in the other thread to determine the path and put that full path into dlopen.

[Arie Stavchansky]

Many thanks for your guidance and time, Toby!  I will get to it and post back with results. 

[Arie Stavchansky]

I took a look at the links you sent, but I still do not understand how to actually make the call to the function in the dynamic library.

so far i have something like:

void* extLibrary;

void* libFunction;

extLibrary = dlopen("/Library/Application Support/MyApp/extLib.dylib");

libFunction = dlsym(extLibrary, "my_fancy_function");

What I don't understand is how to actually call the function in the dynamic library and how do I pass parameter values to that function?

[Guest]

I assume you know the syntax of the function to be called?

If so, just cast the void pointer you get from dlsym() to a function pointer matching the declaration of your desired function.

Basically the same stuff as on Windows with LoadLibrary()

Here is a simple example with 2 int params:

typedef void (*my_fancy_function_type)(int, int);

my_fancy_function = (my_fancy_function_type)libFunction;

// now you can call your function:

my_fancy_function(12, 34);

[Guest]

All of this code above applies however only if you want to load a .dylib at runtime and dynamically load a function from it.

If you don't need runtime loading, there is also (just like on Windows with lib+dll) the option to link directly to the .dylib from within Xcode, then you only need the header file for the declaration and a path to the .dylib in the Xcode library settings.

[Arie Stavchansky]

I don't need it at runtime, but I was getting the same error from AE about my plugin being invalid.  I essentially added the .dylib file to the list of dynamic libraries under the "Link Binary With Libraries" heading in the "Build Phases" tab of my bundle target.  Then I added the path to the .dylib file under the "Library Search Paths" setting under the "Build Settings" tab of my target.

I do have a header file for the .dylib, and I placed it in my plugin's code.  XCode built the plugin successfully, but when I went to apply it on a layer in AE, it just gave me an error that said "Could not find entry point", then it said "Invalid Filter".  So, that was the same error I was receiving on the windows side.  Is there anything I'm missing to make sure the .dylib loads correctly if I don't want to do run time loading?

[Guest · Accepted solution]

Ah, ok, that should make things easier. So where did you put your dylib file? Same as with Windows, it needs to be in a location referenced in the path environment variable or in the location of the calling application. Easiest thing to test will probably if you put it in /usr/lib or /usr/local/lib (for global access) or ~/lib for the current user only.
See also here: Using Dynamic Libraries

[Arie Stavchansky]

Toby,

You're amazing!  Thank you for your help on this and for your mentorship.  It works now on OSX.

—Arie