Re: [libvirt PATCH v2 1/1] meson: Drop RPATH usage

On Wed, Aug 19, 2020 at 02:10:53PM +0200, Pavel Hrdina wrote: > On Wed, Aug 19, 2020 at 01:22:58PM +0200, Pavel Hrdina wrote: > > On Wed, Aug 19, 2020 at 12:47:40PM +0200, Andrea Bolognani wrote: > > > Right now we're unconditionally adding RPATH information to the > > > installed binaries and libraries, but that's not always desired. > > > > > > Debian explicitly passes --disable-rpath to configure, and while > > > I haven't been able to find the same option in the spec file for > > > either Fedora or RHEL, by running > > > > > > $ readelf -d /usr/bin/virsh | grep PATH > > > > > > I can see that the information is not present, so I assume they > > > also strip it somehow. > > > > > > Both Debian and Fedora have wiki pages encouraging packagers to > > > avoid setting RPATH: > > > > > > https://wiki.debian.org/RpathIssue > > > https://fedoraproject.org/wiki/RPath_Packaging_Draft > > > > > > Given the above, it looks like it's actually better to not go > > > out of our way to include that information in the first place. > > > > I need to look into this because I remember adding the rpath there as > > a result that something was not working correctly but now I don't > > remember what was it. Originally I did not have it there. > > > > Pavel > > So I managed to remember what was the issue. If you run install libvirt > into custom directory like this: > > meson build --prefix /my/custom/dir > ninja -C build install > > and after that running: > > /my/custom/dir/bin/virsh > > will fail with: > > /lib64/libvirt.so.0: version `LIBVIRT_PRIVATE_6.7.0' not found (required by ./bin/bin/virsh) > > This is what autotools did by default as well and I did not know that > there is an option --disable-rpath as it's not in output of > `./configure --help`. > > If we don't care about the use case of installing libvirt into custom > prefix and breaking it it should be OK to remove this from meson but my > guess is that we should not do it. So it is only broken if you failed to set LD_LIBRARY_PATH. rpath is basically hardcoding the association between the virsh binary and the library so that it doesn't need LD_LIBRARY_PATH. I'm ambivalent on whether that's important or not, though admittedly it can avoid surprises for users not used to LD_LIBRARY_PATH type issues. IIUC, meson sets rpath automatically for the binaries so you can run from the non-installed build dir. When you run install, it then strips the rpath for the build dir, optionally replacing it with the "install_rpath" value.