Truly-dynamic linked libraries how?

Truly-dynamic linked libraries how?

Post by Trevor Jenki » Sat, 02 Nov 1996 04:00:00



I'm a recovering VMS and Microsoft Windows programmer. One feature that
both those programming environments have is dynamic linked libraries. The
UNIX (*) dynamic linked library concept does not appear to be equivalent.

For those people who know the VMS RTL what I'm looking for (and not
finding) in UNIX) is the equivalent of the LIB$FIND_IMAGE_SYMBOL/LIB$CALLG
calls. Does such a feature exist in UNIX? If so, where can I find out about
it? apropos dymanic refers me to ld.so, which from the "extensive" :-; man
page, does not provide the same functionality--it apears closer to
LINK/SHARE with LIBRARY/SHARE than the above function calls.

Regards, Trevor.

--

"Real Men don't Read Instruction Manuals"
   Tim Allen, Home Improvement

 
 
 

Truly-dynamic linked libraries how?

Post by Andrew Gabri » Sun, 03 Nov 1996 04:00:00




Quote:>I'm a recovering VMS and Microsoft Windows programmer. One feature that
>both those programming environments have is dynamic linked libraries. The
>UNIX (*) dynamic linked library concept does not appear to be equivalent.

>For those people who know the VMS RTL what I'm looking for (and not
>finding) in UNIX) is the equivalent of the LIB$FIND_IMAGE_SYMBOL/LIB$CALLG
>calls. Does such a feature exist in UNIX? If so, where can I find out about
>it? apropos dymanic refers me to ld.so, which from the "extensive" :-; man
>page, does not provide the same functionality--it apears closer to
>LINK/SHARE with LIBRARY/SHARE than the above function calls.

Look to see if your unix system has dlopen and dlsym.

--



 
 
 

Truly-dynamic linked libraries how?

Post by Jens-Uwe Mag » Sun, 03 Nov 1996 04:00:00




> I'm a recovering VMS and Microsoft Windows programmer. One feature that
> both those programming environments have is dynamic linked libraries. The
> UNIX (*) dynamic linked library concept does not appear to be equivalent.

> For those people who know the VMS RTL what I'm looking for (and not
> finding) in UNIX) is the equivalent of the LIB$FIND_IMAGE_SYMBOL/LIB$CALLG
> calls. Does such a feature exist in UNIX? If so, where can I find out about
> it? apropos dymanic refers me to ld.so, which from the "extensive" :-; man
> page, does not provide the same functionality--it apears closer to
> LINK/SHARE with LIBRARY/SHARE than the above function calls.

I am not sure what the VMS routines do, but I would believe dlopen() and
dlsym() would be the equivalents on Unix.
_______________________________________________________________________


Brahmsstr. 3                    Tel.: +49 511 660238
 
 
 

Truly-dynamic linked libraries how?

Post by Trevor Jenki » Tue, 05 Nov 1996 04:00:00




Quote:> >I'm a recovering VMS and Microsoft Windows programmer. One feature that
> >both those programming environments have is dynamic linked libraries. The
> >UNIX (*) dynamic linked library concept does not appear to be equivalent.

> Look to see if your unix system has dlopen and dlsym.

Sadly, my Linux 1.2.8 system does not. :-( Whether Linux 2.0.x does I do
not know yet---I plan to upgrade to this soon. Perhaps in the meantime
someone could me tell if those routines are there?

Regards, Trevor.

--

"Real Men don't Read Instruction Manuals"
   Tim Allen, Home Improvement

 
 
 

Truly-dynamic linked libraries how?

Post by gues » Tue, 05 Nov 1996 04:00:00





:
: > >I'm a recovering VMS and Microsoft Windows programmer. One feature that
: > >both those programming environments have is dynamic linked libraries. The
: > >UNIX (*) dynamic linked library concept does not appear to be equivalent.
: >
: > Look to see if your unix system has dlopen and dlsym.
:
: Sadly, my Linux 1.2.8 system does not. :-( Whether Linux 2.0.x does I do
: not know yet---I plan to upgrade to this soon. Perhaps in the meantime
: someone could me tell if those routines are there?

  Linux 1.2.8 ?? I believe you mean the kernel version. First, dynamic
  loading itself is an application facility without requiring kernel
  support in general. Second, ELF binary (and thus, dlxxx()) are supported
  on many 1.x linux(read linux ELF faq please), At least I used(very
  happily)dlxxx() a lot on 1.2.x and 1.3.x last year. Third, gnu dld 2.7
  supports dynamic loading of old .o binary on linux without ELF. Even
  gnu dld is almost useless comparing to ELF dlxxx(), but it shows a
  pure user level dynamic loading can be implemented.

  -g

 
 
 

Truly-dynamic linked libraries how?

Post by Jens-Uwe Mag » Tue, 05 Nov 1996 04:00:00






> > >I'm a recovering VMS and Microsoft Windows programmer. One feature that
> > >both those programming environments have is dynamic linked libraries. The
> > >UNIX (*) dynamic linked library concept does not appear to be equivalent.

> > Look to see if your unix system has dlopen and dlsym.

> Sadly, my Linux 1.2.8 system does not. :-( Whether Linux 2.0.x does I do
> not know yet---I plan to upgrade to this soon. Perhaps in the meantime
> someone could me tell if those routines are there?

This does not depend upon Linux kernel version - it depends upon the binary
object file format of the Linux distribution you installed. Linux supports
dlopen() if you are using the ELF binary format which can be used with the
kernels 1.2.13 or 2.0.x.
_______________________________________________________________________


Brahmsstr. 3                    Tel.: +49 511 660238
 
 
 

Truly-dynamic linked libraries how?

Post by Trevor Jenki » Wed, 06 Nov 1996 04:00:00





> > > >I'm a recovering VMS and Microsoft Windows programmer. One feature that

> > > Look to see if your unix system has dlopen and dlsym.

> > Sadly, my Linux 1.2.8 system does not. :-(
> This does not depend upon Linux kernel version - it depends upon the binary
> object file format of the Linux distribution you installed.

Well I did say I was a VMS programmer in recovering by using UNIX (okay I
maybe should have said Linux :-). :-)

Quote:> Linux supports
> dlopen() if you are using the ELF binary format which can be used with the
> kernels 1.2.13 or 2.0.x.

Now I have the "perfect" excuse to upgrade my kernel and to convert over to
ELF. :-)

Thanks to all those who replied to my seemingly trivial question but when
you've spent more than a dozen years with VMS there are certain routines
that one "needs" in order to get to grips with an new environment.

Regards, Trevor.

--

"Real Men don't Read Instruction Manuals"
   Tim Allen, Home Improvement

 
 
 

Truly-dynamic linked libraries how?

Post by E. Lefty Kreouzi » Thu, 07 Nov 1996 04:00:00



> I'm a recovering VMS and Microsoft Windows programmer. One feature that
> both those programming environments have is dynamic linked libraries. The
> UNIX (*) dynamic linked library concept does not appear to be equivalent.

By the way they *are* equivalent as far as shared text goes not sure
about
data segents though.

Quote:

> For those people who know the VMS RTL what I'm looking for (and not
> finding) in UNIX) is the equivalent of the LIB$FIND_IMAGE_SYMBOL/LIB$CALLG
> calls. Does such a feature exist in UNIX? If so, where can I find out about
> it? apropos dymanic refers me to ld.so, which from the "extensive" :-; man
> page, does not provide the same functionality--it apears closer to
> LINK/SHARE with LIBRARY/SHARE than the above function calls.

Try man 3 dlopen in Linux-elf, Digital UNIX and probably others.
These are the ones I can look at right now.

Lefty Kreouzis

 
 
 

Truly-dynamic linked libraries how?

Post by Guy Harr » Fri, 08 Nov 1996 04:00:00



Quote:>Try man 3 dlopen in Linux-elf, Digital UNIX and probably others.
>These are the ones I can look at right now.

The interface was designed by AT&T (no, not Sun), but the first UNIX
system to offer them was, I think, SunOS 4.1[.x] (4.0[.x] didn't have
them).  In addition to the systems mentioned, SVR4-flavored systems
including SunOS 5.x should have them, and I think {Free,Net,Open}BSD
have them as well.
 
 
 

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ignore my last posting, i found that if i stuck the static library in
as an object file it still didn't work.  must be something work with my
compilation.

========================================================================


========================================================================

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