proton: Improve find_nvidia_wine_dll_dir() handling of missing filesexperimental-6.3-20210602b

Additionally split out the find_library() logic for discovery of libdl
so that the case of a missing libdl (no matter how unlikely) is caught
before attempting to load an erroneous CDLL.

Fixes: 4881 (Latest Proton Experimental Fails To Open)

Reviewed-by: Adam Moss <amoss@nvidia.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/proton b/proton
index a36c7071..a9cfa2ed 100755
--- a/proton
+++ b/proton
@@ -148,10 +148,20 @@ def try_get_game_library_dir():
 #
 # On failure, returns None
 def find_nvidia_wine_dll_dir():
-    libdl = CDLL(find_library("libdl"))
-    libglx_nvidia = CDLL("libGLX_nvidia.so.0")
+    try:
+        libdl_soname = find_library("dl")
+
+        # If we couldn't determine the proper soname for libdl, bail out.
+        if libdl_soname is None:
+            return None
+
+        libdl = CDLL(libdl_soname)
+    except (FileNotFoundError, OSError):
+        return None
 
-    if libdl is None or libglx_nvidia is None:
+    try:
+        libglx_nvidia = CDLL("libGLX_nvidia.so.0")
+    except OSError:
         return None
 
     # from dlinfo(3)