Keep libfakeinput's C++ runtime private

libfakeinput.so links libstdc++ and libgcc statically and is preloaded into
every session process, so it exported the whole C++ runtime (~7000 symbols,
__gxx_personality_v0 and __cxa_* among them). Programs then unwound through
its copy: shadPS4 aborted in pthread_exit the first time a game thread ended
(forced unwind -> foreign personality -> terminate). Link with
--exclude-libs,ALL so only the input hooks are exported, fail the build if
the runtime leaks out again, and bump the preload cache so it is rebuilt.

.github/workflows/build.yml

@@ -26,7 +26,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  PRELOAD_CACHE_VERSION: v1
+  PRELOAD_CACHE_VERSION: v2
 
 jobs:
   build:
@@ -160,7 +160,7 @@ jobs:
           D=app/src/main/assets/linuxfs
           mkdir -p "$D"
           aarch64-linux-gnu-g++ -shared -fPIC -O2 -Wall -Wno-attributes -Wno-nonnull-compare \
-            -pthread -std=c++17 -static-libstdc++ -static-libgcc \
+            -pthread -std=c++17 -static-libstdc++ -static-libgcc -Wl,--exclude-libs,ALL \
             -o "$D/libfakeinput.so" app/src/main/cpp/fakeinput_steam.cpp -ldl
           aarch64-linux-gnu-strip --strip-unneeded "$D/libfakeinput.so"
           aarch64-linux-gnu-gcc -shared -fPIC -O2 -Wall -pthread \
@@ -270,6 +270,12 @@ jobs:
           for sym in open openat ioctl read close poll ppoll select stat fstat access scandir; do
             grep -qx "$sym" <<<"$FAKE" || { echo "::error::libfakeinput.so does not export $sym"; exit 1; }
           done
+          # The static C++ runtime stays private: every session process preloads this library,
+          # and an exported personality routine takes over other programs' unwinding (shadPS4
+          # aborted in pthread_exit).
+          if grep -qxE '__gxx_personality_v0|__cxa_throw|_Unwind_Resume' <<<"$FAKE"; then
+            echo "::error::libfakeinput.so exports the C++ runtime"; exit 1
+          fi
           SESSION=$(syms "$D/libblsession.so")
           for sym in socket bind getsockname setsockopt statfs statvfs; do
             grep -qx "$sym" <<<"$SESSION" || { echo "::error::libblsession.so does not export $sym"; exit 1; }

tools/build_local.sh

@@ -100,7 +100,7 @@ docker run --rm --platform linux/amd64 \
         d=app/src/main/assets/linuxfs
         mkdir -p "$d"
         aarch64-linux-gnu-g++ -shared -fPIC -O2 -Wall -Wno-attributes -Wno-nonnull-compare \
-            -pthread -std=c++17 -static-libstdc++ -static-libgcc \
+            -pthread -std=c++17 -static-libstdc++ -static-libgcc -Wl,--exclude-libs,ALL \
             -o "$d/libfakeinput.so" app/src/main/cpp/fakeinput_steam.cpp -ldl
         aarch64-linux-gnu-strip --strip-unneeded "$d/libfakeinput.so"
         aarch64-linux-gnu-gcc -shared -fPIC -O2 -Wall -pthread \