dlopen portability

[Tobias Oed]

Hello,
On linux there is an interface to dynamically link against shared libraries
using the functions,

void *dlopen(const char *filename, int flag);
const char *dlerror(void);
void *dlsym(void *handle, char *symbol);
int dlclose(void *handle);

Most of my man pages have a section CONFORMING TO at the end, but not the
one for these functions. There is an (unusual) section
ACKNOWLEDGEMENTS
The dlopen interface standard comes from Solaris.

I was wondering how portable this interface was to other unixen then
linux/solaris? xxBSD/True 64/HP-UX/etc.
Thanks!
Tobias.

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[Bjorn Reese]

Tobias Oed wrote:

> I was wondering how portable this interface was to other unixen then
> linux/solaris? xxBSD/True 64/HP-UX/etc.

The dlopen interfaces are part of the SUSv2 (aka UNIX98) standard.
It is implemented on many Unices that predate this standard.

[phil-news-nospam@ipal.net]

On Wed, 30 Jul 2003 11:02:56 -0700 William Ahern <william@wilbur.25thandclement.com> wrote:
| Tobias Oed <tobias@physics.odu.edu> wrote:
|> Hello,
|> On linux there is an interface to dynamically link against shared libraries
|> using the functions,
|>
|> void *dlopen(const char *filename, int flag);
|> const char *dlerror(void);
|> void *dlsym(void *handle, char *symbol);
|> int dlclose(void *handle);
|
|> Most of my man pages have a section CONFORMING TO at the end, but not the
|> one for these functions. There is an (unusual) section
|> ACKNOWLEDGEMENTS
|> The dlopen interface standard comes from Solaris.
|>
|> I was wondering how portable this interface was to other unixen then
|> linux/solaris? xxBSD/True 64/HP-UX/etc.
|> Thanks!
|> Tobias.
|
| Many people use GNU Autotools' Libtool library/interface. It smoothes over
| the edges for portable applications. For instance, OpenBSD has dlopen()
| available from libc, whereas on Linux you have to link to libdl; OTOH
| OpenBSD doesn't support the RTLD_NEXT handler.

I found dlopen() in SUSv3. The RTLD_NEXT option is not listed, so SUSv3
does not appear to require it. So it could be the case that OpenBSD is in
full conformance for dlopen().

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-----------------------------------------------------------------------------
| Phil Howard KA9WGN | [url]http://linuxhomepage.com/[/url] [url]http://ham.org/[/url] |
| (first name) at ipal.net | [url]http://phil.ipal.org/[/url] [url]http://ka9wgn.ham.org/[/url] |
-----------------------------------------------------------------------------

[William Ahern]

[email]phil-news-nospam@ipal.net[/email] wrote:

> I found dlopen() in SUSv3. The RTLD_NEXT option is not listed, so SUSv3
> does not appear to require it. So it could be the case that OpenBSD is in
> full conformance for dlopen().

According to the following (registration required) RTLD_NEXT is reserved
for future use.

[url]http://www.opengroup.org/onlinepubs/007904975/functions/dlsym.html[/url]

It'd be extremely nice if OpenBSD didn't wait to implement it.