Cross-platform dynamic libraries (GNU/Linux, Mac OS X, Windows, ...)

[Hugues De Keyzer]

Gregor Richards wrote:
> Hugues De Keyzer wrote:
>> Hi,
>>
>> I'm planning to create a multi-platform (at least GNU/Linux, Mac OS X 
>> and Windows) application in D. One of its key characteristics is that 
>> it will be based on modules (plug-ins). Ideally, functionalities more 
>> advanced than just normal shared libraries would be desirable.
>>
>> I took a look at DDL, but it seems to be targeted only at Windows.
>>
>> I made some dlopen() tests on Mac OS X 10.4 with gdc. It works, as 
>> long as the garbage collector isn't involved in the library. 
>> Instancing a class in the library works only if new() and delete() are 
>> defined and don't call the gc. When new() and delete() are not 
>> defined, instancing a class results in a bus error. gdb gives the 
>> following message:
>>
>> Program received signal EXC_BAD_ACCESS, Could not access memory.
>> Reason: KERN_PROTECTION_FAILURE at address: 0x00000000
>> 0x0005389a in _d_newclass ()
>>
>> I also tried calling std.gc.setGCHandle(), but it also fails:
>>
>> Program received signal EXC_BAD_ACCESS, Could not access memory.
>> Reason: KERN_PROTECTION_FAILURE at address: 0x00000000
>> 0x00053435 in std.gc.addRange(void*, void*) ()
>>
>> This may sound like a newbie question, but is there an easy way (or a 
>> way at all) to develop a cross-platform application in D with shared 
>> libraries?
>>
>> Dynamic linking is a very useful feature for software development. 
>> Including this in the D specification (like threads) would be great.
>>
>> Hugues De Keyzer
>>
>> -- 
>> The only constant in life is change
>>    -- www.wikipedia.org
> 
> GDC supports proper .so files on all platforms with .so files. Build the 
> ..so files without a standard library (-no-stdlib or something like 
> that) and then build the host exporting dynamic symbols (default on OS 
> X, -rdynamic on everything else). DSSS, of course, does all of this for 
> you.
> 
> Windows DLL's will never be capable of full, proper support until phobos 
> is in a .dll. Even then, if there was conflicting typeinfo, it could 
> still fail. However, DDL ought to cover it there.
> 
>  - Gregor Richards

Thank you for this quick reply. I tested on Mac OS X with -nostdlib and 
had of course undefined references. After some more searching, I 
succeeded in building a dynamic library with the following options:

gdc -dynamiclib -nostdlib -undefined dynamic_lookup -o mylib.so mylib.d

This seems to work. The GC works fine.

Another question: is it safe to directly load a mangled D symbol like this:

void* test = dlsym(handle, "_D8mymodule8MyModule4testFZv");

for static void MyModyle.test()?

It works, but will it work an all platforms?

-- 
The only constant in life is change
    -- www.wikipedia.org