[Sbcl-help] Re: [Sbcl-devel] Module loading on Darwin / OS X

[Daniel B. <da...@te...>]

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[ CCed sbcl-help in the hope of reaching actual users who aren't also
developers ]

Brian Mastenbrook <cha...@ac...> writes:

> I'm looking from some feedback from anybody who interfaces SBCL with FFI
> code.

> When you load foreign code, do you load more than one DSO, and do
> undefined symbols in one of these DSOs resolve to symbols in another of
> these DSOs? Can this situation be worked around on OS X?

For Linux, and I'm guessing for other ELF-based platforms, the
convention when linking a library is to pass -l options for other
libraries it depends on.  For example

:; ldd /usr/X11R6/lib/libXt.so.6
        libX11.so.6 =3D> /usr/X11R6/lib/libX11.so.6 (0x40054000)
        libSM.so.6 =3D> /usr/X11R6/lib/libSM.so.6 (0x40110000)
        libICE.so.6 =3D> /usr/X11R6/lib/libICE.so.6 (0x40118000)
        libc.so.6 =3D> /lib/libc.so.6 (0x4012d000)
        libdl.so.2 =3D> /lib/libdl.so.2 (0x4023d000)
        /lib/ld-linux.so.2 =3D> /lib/ld-linux.so.2 (0x80000000)

so I would expect that references to, say, XOpenDisplay in libXt will
get resolved to libX11 even if Xt is dlopened without RTLD_GLOBAL.  In
fact, I would tend to consider that a library not built this is buggy.

If SBCL is using RTLD_GLOBAL it's at least as likely for historical
nobody-quite-understood-this or it-used-to-be-buggy[*] reasons as it is
for any actual purpose.=20=20

[*] I have a dim recollection that, yes, it was buggy, once upon a
time.  Early Linux libc 5, or so.

=2D -dan

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