Hi Jason,
some general things about linking:
- The symbolic link(s) libcrypto.so pointing to libcrypto.so.0.9.8
are only needed during BUILD time. On a host where no compiling
happens the symbolic links are not required.
- While linking the application, the linker opens the library
libcrypto.so.0.9.8 by accessing the symbolic link
libcrypto.so and reads its SONAME:
$ objdump -x /usr/lib/libcrypto.so | grep SONAME
This name (which has no path) is added to your application:
$ objdump -x /usr/bin/openssl | grep NEEDED
- When executing the application, the /lib/ld-linux.so link helper
searches in the well known places $LD_LIBRARY_PATH:/lib:/usr/lib
for the libraries and opens them recursively.
To show which library file is actually used during execution, call:
$ ldd /usr/bin/openssl
To solve your problem, I suggest to compile but not install "openssl-1.0.1c"
on the second machine and only copy the resulting libraries "libssl.so.1.0.0"
and "libcrypto.so.1.0.0" to /usr/lib without touching their names, the symlinks
nor the include/openssl.
This way, any application compiled on that host will link to 0.9.8,
while applications compiled against 1.0.x will also run smoothly.
HTH
Christian
On Wed, Jun 20, 2012 at 05:56:07PM +0000, Jason Schultz wrote:
>
>
>
>
> I'm building and running an application that uses OpenSSL on SUSE Linux. I
> don't know a lot about linking in general, just very basic stuff, so my
> question might be better posed to a Linux forum, but it might be specific to
> OpenSSL. Let me describe the scenario.
>
> I have built installed OpenSSL 1.0.1c on one machine; built as a shared
> library(with "shared" option on ./config). I build my application and run it
> on this machine, dynamically linking OpenSSL. After some trial and error(to
> get the application to use the new OpenSSL instead of the the previous
> install of 0.9.8r), everything works fine, my application is using OpenSSL
> 1.0.1c. Now, let's say I want to run my application on another SUSE Linux
> machine. However, this machine has 0.9.8r(or any 0.9.8 level) installed.
> When I try to run the application, I get an error saying it can't find
> OpenSSL 1.0.0. I know that there are symbolic links set up when installing
> OpenSSL, so libssl.so will be linked to libssl.so.1.0.0 after installing
> OpenSSL 1.0.1c. (Similar for libcrypto.so) But in the old branch, the link is
> set up with libssl.so pointing to libssl.so.0.9.8. When I build my
> application, it seems to know that it's looking for libssl.so.1.0.0, instead
> of just the generic libssl.so. I'm basing this on doing a readelf -d on my
> the .so file my make produces, and seeing the following line: (NEEDED)
> Shared library: [libssl.so.1.0.0]
> On the machine I moved my application to(with the older OpenSSL), the link
> where OpenSSL exists shows libssl.so linked to libssl.so.0.9.8, obviously. I
> started messing around with trying to build 1.0.1c to "look like" 0.9.8 by
> changing the SHLIB_VERSION_NUMBER in Makefile.org and /crypto/opensslv.h, but
> that started getting confusing and is probably beyond the scope of my
> knowledge at this point. I've done it before with, for example, going from
> 0.9.8i to 0.9.8r and didn't have any problems. I suppose because the
> symbolic links look the same. Has anyone had to do this before? A point in
> the right direction would be appreciated. Is this even possible to go
> between branches like that?
>
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