- Reduce unnecessary linking

[yan12125]

When pyunbound is enabled while pythonmodule is not (i.e., ./configure --without-pythonmodule --with-pyunbound), only the Python library _unbound.so uses Python functions, and main programs (unbound, unbound-anchor, ...) and libunbound.so do not. This patch removes unneeded linking.

Note that I didn't commit re-generated autoconf files as that brings too many unrelated changes to ./configure. If you wish, I will push updated autoconf files.

[ArchangeGabriel]

At the same time, there is overlinking happening there:

python-unbound W: Unused shared library '/usr/lib/libssl.so.1.1' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libsodium.so.23' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libprotobuf-c.so.1' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libevent-2.1.so.7' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libsystemd.so.0' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libcrypto.so.1.1' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libhiredis.so.1.0.0' by file ('usr/lib/python3.9/site-packages/_unbound.so')
python-unbound W: Unused shared library '/usr/lib/libnghttp2.so.14' by file ('usr/lib/python3.9/site-packages/_unbound.so')

EDIT: The usual sed -i -e 's/ -shared / -Wl,-O1,--as-needed\0/g' libtool workaround works for this though.

[yan12125]

At the same time, there is overlinking happening there:

Many thanks for testing! I looked into it, and found two issues:

• Unbound's Makefile specifies unneeded libraries for _unbound.so. I address that issue in the updated patch.
• libtool brings unneeded libraries. For example, using ./configure --with-pythonmodule --with-pyunbound, build commands for _unbound.so are:

./libtool --tag=CC --mode=link gcc  -I. -I/usr/include/python3.9 -DSRCDIR=. -g -O2 -flto -pthread  -module -avoid-version -no-undefined -shared -o _unbound.la libunbound_wrap.lo -rpath /usr/lib/python3.9/site-packages libunbound.la -L/usr/lib -L/usr/lib/python3.9 -L. -lpython3.9
libtool: link: rm -fr  .libs/_unbound.la .libs/_unbound.lai .libs/_unbound.so
libtool: link: gcc -shared  -fPIC -DPIC  .libs/libunbound_wrap.o   -Wl,-rpath -Wl,/home/yen/var/unbound/.libs -Wl,-rpath -Wl,/usr/local/lib ./.libs/libunbound.so -L/usr/lib -L/usr/lib/python3.9 -L. -lssl -lcrypto -lpython3.9  -g -O2 -flto -pthread   -pthread -Wl,-soname -Wl,_unbound.so -o .libs/_unbound.so

Here -lssl and -lcrypto do not appear in the first libtool command, but the final gcc command includes them. Googling around, besides the sed command you've mentioned, I also found discussions about linking "recursively" by libtool and a patch from Debian to disable it. I guess that is the cause why -lssl and -lcrypto are added to _unbound.so - both libraries are used by libunbound. Hopefully, with this patch, linking is correct for distros that disable recursive linking without further patching.

/cc @orbea Mind to test this patch on Gentoo with slibtool? I found that $(LIBS) is added for _unbound.so in #449. I guess replacing $(LIBS) with $(PYTHON_LIBS) will not break things on Gentoo, but more testing will be better.

[orbea]

This patch seems to compile correctly using slibtool, the current git head (dd25413) and --with-pyunbound.

I think the only way this could fail with slibtool is if $(LIBS) contains any required references that $(PYTHON_LIBS) does not also contain which would then fail with -no-undefined which GNU libtool silently ignores, but that doesn't seem to be the case.

[yan12125]

Thanks a lot for testing and clear explanations!

[yan12125]

Rebased to resolve conflicts after 8e538dc

[gthess]

Thanks for this! LGTM and the Python tests pass.