subreaper: handle mangohud for opengl applications

rare/commands/subreaper/subreaper_linux.py

@@ -11,6 +11,8 @@
 from pathlib import Path
 from typing import Any, Generator, List
 
+from .util import find_mangohud_bin, find_mangohud_shim
+
 # Constants defined in prctl.h
 # See prctl(2) for more details
 PR_SET_NAME = 15
@@ -99,6 +101,12 @@ def signal_handler(sig, frame):
     prctl_ret = prctl(PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0, 0)
     logger.debug("prctl PR_SET_CHILD_SUBREAPER exited with status: %s", prctl_ret)
 
+    if os.environ.get("MANGOHUD") == "1":
+        if mangoshim := find_mangohud_shim():
+            os.environ["LD_PRELOAD"] = f'{os.environ.get("LD_PRELOAD", "")}:{mangoshim}'
+        elif mangobin := find_mangohud_bin():
+            command.insert(0, mangobin)
+
     pid = os.fork()  # pylint: disable=E1101
     if pid == -1:
         logger.error("Fork failed")

rare/commands/subreaper/util.py

@@ -0,0 +1,39 @@
+import os
+import shutil
+from typing import List
+
+
+def find_all(name, path) -> List:
+    result = []
+    for root, dirs, files in os.walk(path):
+        if name in files:
+            result.append(os.path.join(root, name))
+    return result
+
+
+def find_mangohud_shim() -> str:
+    libs = find_all("libMangoHud_shim.so", "/usr")
+    if 1 > len(libs) > 2:
+        return ""
+    if len(libs) == 1:
+        return libs[0]
+    ret = []
+    for left, right in zip(*(lib.split("/") for lib in libs)):
+        if left == right:
+            ret.append(left)
+        elif left.startswith("lib") and right.startswith("lib"):
+            ret.append("$LIB")
+        else:
+            return ""
+    return "/".join(ret)
+
+
+def find_mangohud_bin() -> str:
+    return shutil.which("mangohud")
+
+
+if __name__ == "__main__":
+    print(find_mangohud_shim())
+
+
+__all__ = ["find_mangohud_shim", "find_mangohud_bin"]