Building on musl fails to link against libanl when not using static linking (aka MUSL_OPTIMIZED_BUILD)

[hhoffstaette]

Describe the bug

sysdig can be built with MUSL_OPTIMIZED_BUILD - unfortunately this is misleading as it implies static linking and statically built dependencies, which is not necessary on musl.
I found that using a regular build against unbundled dependencies on musl fails, as falcosecurity-libs tries to unconditionally link against libanl, which does not exist on musl.

How to reproduce it

Build sysdig on musl with MUSL_OPTIMIZED_BUILD disabled and unbundled dependencies built as shared libs. It should error out with a failure to link -lanl.

Expected behaviour

sysdig should build successfully on musl against shared unbundled dependencies.

Environment

• musl 1.2.5 in a Gentoo chroot (with musl as system C library)

• Installation method: from source - I am the package maintainer :)

Additional information

We had to fix this in Gentoo for an older version in this commit:
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=844fbd1e96beda0fb94ea06aba8f2618bfdad1f7

[hhoffstaette]

For libs-0.17.2 I had to rebase the patch (while finally updating our sysdig package to 0.38.0) and it looks like this:

--- libs-0.17.2/userspace/libsinsp/CMakeLists.txt~	2024-06-14 11:38:50.000000000 +0200
+++ libs-0.17.2/userspace/libsinsp/CMakeLists.txt	2024-07-05 00:18:03.326406540 +0200
@@ -258,8 +258,8 @@ if(NOT WIN32)
 			)
 
 			if(NOT MUSL_OPTIMIZED_BUILD)
-				target_link_libraries(sinsp INTERFACE rt anl)
-				list(APPEND SINSP_PKGCONFIG_LIBRARIES rt anl)
+				target_link_libraries(sinsp INTERFACE rt)
+				list(APPEND SINSP_PKGCONFIG_LIBRARIES rt)
 			endif()
 
 		else()

Obviously this is not correct on glibc systems, so the patch is only applied conditionally when building on musl. Can we somehow sanitize this without breaking things?

[FedeDP]

Hi! Thanks for opening this issue :)
Mmh perhaps we could only link anl if we can find it in the system? Likely using find_library ?

[hhoffstaette]

Hi! Thanks for opening this issue :) Mmh perhaps we could only link anl if we can find it in the system? Likely using find_library ?

Yes, that would be one option. Like I said in the Gentoo bug mentioned above, libanl has only been an empty stub for quite some time now (since ~2021), so it's not even that critical any more.

[FedeDP]

Opened #2036 to fix this ;)

[FedeDP]

/milestone 0.19.0

[FedeDP]

/milestone 0.18.0