[openssl-users] openssl 1.0 and 1.1 co-exist

[Viktor Dukhovni]

On Wed, Jun 21, 2017 at 01:44:34PM -0400, Ken Goldman wrote:

> This is probably Linux specific ...
> 
> Can both openssl versions co-exist on the same platform.  I know that the
> .so is versioned, but how about the header files?  Can I choose which
> library to build with?

Yes, with care.  I support systems where the base platform (debian)
provides OpenSSL 1.0.1 in /usr/{include,lib,bin}, and I additionally
deploy OpenSSL 1.0.2 and OpenSSL 1.1.0 in:

	/opt/openssl/1.0/{include,lib,bin}	OpenSSL 1.0.2
	/opt/openssl/1.1/{include,lib,bin}	OpenSSL 1.1.0

These builds employ custom ELF symbol versions and custom ELF
SONAMEs, and custom RPATHs, so that they can coexist without conflict
in a single running process with the system OpenSSL library.

Applications that use my builds can then be compiled with (for
example):

    -I/opt/openssl/1.1/include \
    -L/opt/openssl/1.1/lib \
    -Wl,-R,/opt/openssl/1.1/lib

> Do the headers go in the same /usr/include/openssl or are there links?
> 
> Are there ifdefs in the header files.
> 
> Is there a FAQ covering this?

Not that I've seen.

-- 
	Viktor.