setup.sh: Special-case libudev.so.0.0.9999 as newer than our libudev.…

…so.0

Steam Runtime 1 'scout' is based on a library stack from 2012, so it
includes libudev.so.0 v175, from before libudev was merged into systemd
and bumped its SONAME to libudev.so.1. libudev.so.0 and libudev.so.1
mostly export the same symbols, and the symbols in libudev.so.0 don't
use ELF symbol versioning, so if we load both libudev.so.0 and
libudev.so.1 into the same process, libudev.so.0 will "win". This
can cause crashes if another module of the same process calls functions
that are unique to libudev.so.1, by sharing data structures between
libraries that were never intended to share them.

There is a libudev0-shim project, originating in Arch Linux and now
offered by several other distributions such as Debian, which provides a
drop-in replacement for the legacy libudev.so.0. Unfortunately, the
legacy libudev.so.0 is versioned as .so.0.13.0, while Arch's shim is
currently versioned as .so.0.0.9999 (archlinux/libudev0-shim#4), so we
would normally assume our legacy version is actually newer.

If we special-case Arch's shim to be considered to be newer than the
Steam Runtime's legacy version, then we'll load the shim version whenever
it's available at OS level, avoiding crashes.

Part-of: steamrt/tasks#313
Helps: ValveSoftware/steam-for-linux#9805
Signed-off-by: Simon McVittie <smcv@collabora.com>

templates/setup.sh

@@ -430,6 +430,12 @@ pin_newer_runtime_libs ()
             runtime_version_newer="yes"
         fi
 
+        if [[ "$soname" == libudev.so.0 && "$h_lib_major.$h_lib_minor.$h_lib_third" == 0.0.9999 ]]; then
+            # Work around https://github.com/archlinux/libudev0-shim/issues/4
+            debug "Treating libudev0-shim as newer than runtime version"
+            runtime_version_newer="no"
+        fi
+
         # Print to stderr because zenity is consuming stdout
         if [[ $runtime_version_newer == "yes" ]]; then
             log "Found newer runtime version for $bitness-bit $soname. Host: $h_lib_major.$h_lib_minor.$h_lib_third Runtime: $r_lib_major.$r_lib_minor.$r_lib_third"