Re: Mac OS X .dylib not working

[Bob Friesenhahn <bfriesen@simple.dallas.tx.us>]

On Tue, 2 Feb 2010, Hans Aberg wrote:

> On 2 Feb 2010, at 15:20, Ken Raeburn wrote:
>
>>>>> On Mac OS X (trying it on 10.5.8 PPC G4), guile-1.8.7 cannot open
>>>>> dynamic library files with name extensions .dylib, but only if they
>>>>> are renamed using .so instead. On the Bug-Guile list they say it
>>>>> just calls libltdl, in the libtool package. I have installed latest
>>>>> of both, but the problem persists:
>>>> 
>>>> libtool should produce modules named *.so on Darwin if you pass the
>>>> -module flag at link time.  Typically, -avoid-version is used for
>>>> modules as well.
>>> 
>>> But dlopen() on Mac OS X can only open files in the native format, which 
>>> isn't ELF, and they are typically named with the .dylib file name 
>>> extension. If it finds a .so file on ELF format, all it does is reporting 
>>> it cannot be opened.
>> 
>> ".so" doesn't mean ELF format, and on some systems including Mac OS X, 
>> "dynamically linked shared library" (e.g., a ".dylib" file) is not the same 
>> as "dynamically loadable object".  Did you not see my earlier email to you 
>> and the bug-guile list?
>
> The fact is that currently Guile, which relies on libtool, cannot open .dylib 
> files, though it works perfectly if they are renamed .so. As for what 
> filenames to use, dlopen() does not care - it is something imposed by 
> libtool. Also, all new native DLLs (see below) on Mac OS X are named .dylib.

Unless I am missing something, the question to be answered is if Guile 
requests opening modules using a name like "module.so" (assuming a 
particular naming scheme), "module.la" (using libltdl as originally 
intended), or bare "module" (using libltdl heuristics, which tries 
several incantations, such as looking for .la, and .so).

OS-X's module loading does not care about the file extension.

Under OS-X (Leopard and later), the 'dtruss' program can be used to 
see what is really going on.

Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/