Re: websockets cmake woes

[Niclas Rosenvik <nros%netbsd.org@localhost>]

On Sun, 13 Oct 2024 10:29:05 -0400
Greg Troxel <gdt%lexort.com@localhost> wrote:

> I just updated mosquitto, which uses websockets.  That exposed a bug
> in the libwebsockets package.  This message is about that bug.
> 
> mosquitto has
> 
>   set (MOSQ_LIBS ${MOSQ_LIBS} websockets_shared)
> 
> when asked to use websockets.  This seemed bizarre to me, but
> apparently this is how the cmake files installed by libwebsockets are
> supposed to work.
> 
> In /usr/pkg/lib/cmake/libwebsockets/LibwebsocketsTargets.cmake
> there is, apparently directly from upstream:
> 
>   set_target_properties(websockets_shared PROPERTIES
>     INTERFACE_INCLUDE_DIRECTORIES
> "${_IMPORT_PREFIX}/include;/usr/include" INTERFACE_LINK_LIBRARIES
> "dl;/usr/lib/libssl.so;/usr/lib/libcrypto.so;/usr/lib/libssl.so;/usr/lib/libcrypto.so"
> )
> 
> and the result is injecting -ldl into the mosquitto build.  That's
> wrong on many systems, including *BSD.
> 
> objdump shows websockets needs
> 
>   NEEDED               libssl.so.15
>   NEEDED               libcrypto.so.15
>   NEEDED               libc.so.12
> 
> and websockets's bl3 includes openssl, so all is ok from the
> straightforward pkgsrc viewpoint.
> 
> The question is then what is the root cause of this (besides "cmake",
> which while not wrong, is unhelpful).
> 
> It seems websockets has defined some complicated scheme supporting
> static and shared libs, but we aren't playing along.   But, I can't
> see anything in the Makefile that tries to change upstream.
> 

The root cause is in lib/CMakeLists.txt where just as nia mentions it
links directly to libdl. I have added a patch to libwebsockets that
makes it link to ${CMAKE_DL_LIBS} instead and it only links privately
to libdl so dl should not turn up on the INTERFACE_LINK_LIBRARIES list
on systems that have libdl either. Try it. 

Regards,
Niclas