On 2011-11-07 13:36, Gor Gyolchanyan wrote:
1. Making shared libraries under Linux work would be a big improvement.
I think you meant "Making shared libraries, written in D, under Linux
work would be a big improvement.", because everything else works fine
(i tested it) using core.sys.posix.dlfn;
Since druntime needs some serious initialization, core.sys.windows.dll
was invented to hide away all this and, if I'm not mistaken, this is
precisely what it means to "support DLLs".
since .so files don't have any auto-called functions, like DllMain,
some additional shenanigans are required to get it to work as in
Windows. There will still be helper functions that would be put inside
some "main" function in .so functions, that should be called
explicitly when loaded (probably inside a standard library loader).
DllMain also has thread/process attach/detach routine callbacks, which
are, AFAIK, are not necessary to simulate in .so files (otherwise,
it'll go inside that pseudo-main function).
Regarding the above information, all I have to do to make "shared
libraries work under linux" is to make linux analogs for the dll
helper functions, define the pseudo-main function requirement in D
docs and make a specialization of LoadLibrary routine in druntime to
call that function.
I have a question regarding the general approach to shared libraries
in D: Should we really use obsolete C library formats and jump through
lots of hoops to work around the limitations?
AFAIK, currently "DLL support" is purely an optional druntime feature,
that allows one to quickly initialize druntime from DllMain by using
the functions for attaching/detaching a thread/process.
I understand, the GC, some handlers (like exception handler) as well
as any other things i don't know about should be properly initialized.
The problem is, that .so files in ELF format don't have anything similar.
In order to make the two consistent some common logic should be
developed on how does D treat
There is a GCC extension available for this:
__attribute__((constructor))
http://stackoverflow.com/questions/2053029/how-exactly-does-attribute-constructor-work
Oh, BTW, generating PIC needs to be fixed first. In addition to the GCC
attribute Mac OS X also have a couple of low level functions for working
with the dynamic linker:
http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/dyld.3.html
Don't know if there's something similar available on Linux.
--
/Jacob Carlborg
