Warn loudly and report native access as denied for PythonContext on unsupported platforms

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/PythonLanguage.java

@@ -59,6 +59,7 @@
 
 import com.oracle.graal.python.builtins.Python3Core;
 import com.oracle.graal.python.builtins.PythonBuiltinClassType;
+import com.oracle.graal.python.builtins.PythonOS;
 import com.oracle.graal.python.builtins.modules.MarshalModuleBuiltins;
 import com.oracle.graal.python.builtins.modules.SignalModuleBuiltins;
 import com.oracle.graal.python.builtins.objects.PNone;
@@ -509,6 +510,13 @@ protected void initializeContext(PythonContext context) {
             }
             initializeLanguage();
         }
+        if (PythonOS.isUnsupported() && context.getEnv().isNativeAccessAllowed()) {
+            LOGGER.log(Level.WARNING, "Loading native libraries into GraalPy on unsupported platforms. " +
+                            "You can ensure that native access is disallowed for this context and configure GraalPy to use Java backends where possible. " +
+                            "Refer to https://www.graalvm.org/python/docs/ for more information on native and Java module backends. " +
+                            "This is not fatal, because other languages may allow native libraries to run on this platform in the same context, " +
+                            "but attempting to load a native library on GraalPy will fail.");
+        }
         context.initializeHomeAndPrefixPaths(context.getEnv(), getLanguageHome());
         context.initialize();
     }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/PythonOS.java

@@ -114,7 +114,7 @@ public static PythonOS getPythonOS() {
                                 "If you are running on a different platform and accept that any functionality that interacts with the system may be " +
                                 "incorrect and Python native extensions will not work, you can specify the system property \"UnsupportedPlatformEmulates\" " +
                                 "with a value of either \"linux\", \"macos\", or \"windows\" to continue further and have GraalPy behave as if it were running on " +
-                                "the OS specified. Loading native libraries will not work and should be disabled using the context options. " +
+                                "the OS specified. Loading native libraries will not work and must be disabled using the context options. " +
                                 "See https://www.graalvm.org/python/docs/ for details on GraalPy modules with both native and Java backends, " +
                                 "and https://www.graalvm.org/truffle/javadoc/org/graalvm/polyglot/Context.Builder.html to learn about disallowing native access.");
             }
@@ -123,12 +123,16 @@ public static PythonOS getPythonOS() {
     }
 
     public static void throwIfUnsupported(String msg) {
-        if (current == PLATFORM_ANY) {
+        if (isUnsupported()) {
             throw new UnsupportedPlatform(msg +
                             "\nThis point was reached as earlier platform checks were overridden using the system property UnsupportedPlatformEmulates");
         }
     }
 
+    public static boolean isUnsupported() {
+        return current == PLATFORM_ANY;
+    }
+
     public static final class UnsupportedPlatform extends AbstractTruffleException {
         public UnsupportedPlatform(String msg) {
             super(msg);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonContext.java

@@ -1256,7 +1256,7 @@ public PythonContext(PythonLanguage language, TruffleLanguage.Env env) {
         this.in = env.in();
         this.out = env.out();
         this.err = env.err();
-        this.nativeAccessAllowed = env.isNativeAccessAllowed();
+        this.nativeAccessAllowed = env.isNativeAccessAllowed() && !PythonOS.isUnsupported();
     }
 
     private static final ContextReference<PythonContext> REFERENCE = ContextReference.create(PythonLanguage.class);
@@ -1446,7 +1446,7 @@ public void setEnv(TruffleLanguage.Env newEnv) {
         err = env.err();
         posixSupport.setEnv(env);
         optionValues = PythonOptions.createOptionValuesStorage(newEnv);
-        nativeAccessAllowed = newEnv.isNativeAccessAllowed();
+        nativeAccessAllowed = newEnv.isNativeAccessAllowed() && !PythonOS.isUnsupported();
     }
 
     /**