At 2004-09-04T23:36:02+1200, Volker Kuhlmann wrote:
> Yes, but that's not with -lXY.
Correct. It's not exactly what you were after, but it may be close
enough to get the results you need.
> I take it there isn't any way to use the linker library search path
> when one needs a specific .so version, and one has to use absolute
> paths and full names. Oh well, it works...
I don't know of one yet.
Note that while you are specifying an absolute path to a particular SO
on the command-line in this case, it's not resulting in that particular
absolute path being required during run-time linking (this aspect would
be affected by ld's -rpath option).
You can achieve the same effect in other ways, e.g. on a system where
linking against libssl.so will get you 0.9.7 by default:
$ ln -s /usr/lib/libssl.so.0.9.6 libssl.so
$ cc x.c -L. -lssl
$ ldd a.out | grep ssl
libssl.so.0.9.6 => /usr/lib/i686/cmov/libssl.so.0.9.6 (0x4002500)
...but this is quite a hack.
What complicates things more is that the compile-time linking is
recording the SONAME of the library you're linking against (0.9.6/0.9.7
in the case of libssl). During run-time linking, the first suitable
library found by the linker with a matching SONAME will be used.
My example with libssl may not have been the best choice, as OpenSSL has
a bit of bad history with SONAME handling. Most libraries will have a
SONAME more like libblah.so.1 (rather than libblah.so.1.0.1). What this
means is that, at link-time, you could specify an absolute path to a
specific major.minor.revision SO, e.g.:
$ cc x.c /path/to/libblah.so.1.0.1
...but the SONAME is recorded in your executable, so during run-time
linking, the linker may find that libblah.so.1.0.2 has a SONAME of
libblah.so.1, so is considered a final matching candidate for that
library.
If you want to know how to use a specific major.minor.revision SO even
when a different version with the same SONAME is available (and the most
likely candidate) on your system, it becomes even trickier still.
Cheers,
-mjg
--
Matthew Gregan |/
/| [EMAIL PROTECTED]
