[GR-14211] Be very careful no to raise in PythonLanguage#toString(PythonContext,Object)

PullRequest: graalpython/420

Author: timfel

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

@@ -46,6 +46,7 @@
 import com.oracle.graal.python.builtins.objects.method.PMethod;
 import com.oracle.graal.python.builtins.objects.module.PythonModule;
 import com.oracle.graal.python.builtins.objects.object.PythonObject;
+import com.oracle.graal.python.builtins.objects.str.PString;
 import com.oracle.graal.python.builtins.objects.type.PythonManagedClass;
 import com.oracle.graal.python.nodes.BuiltinNames;
 import com.oracle.graal.python.nodes.NodeFactory;
@@ -437,16 +438,36 @@ protected SourceSection findSourceLocation(PythonContext context, Object value)
     @Override
     protected String toString(PythonContext context, Object value) {
         final PythonModule builtins = context.getBuiltins();
-        if (builtins == null) {
-            // true during initialization
-            return value.toString();
+        if (builtins != null) {
+            // may be null during initialization
+            Object reprAttribute = builtins.getAttribute(BuiltinNames.REPR);
+            if (reprAttribute instanceof PBuiltinMethod) {
+                // may be false if e.g. someone accessed our builtins reflectively
+                Object reprFunction = ((PBuiltinMethod) reprAttribute).getFunction();
+                if (reprFunction instanceof PBuiltinFunction) {
+                    // may be false if our builtins were tampered with
+                    Object[] userArgs = PArguments.create(2);
+                    PArguments.setArgument(userArgs, 0, PNone.NONE);
+                    PArguments.setArgument(userArgs, 1, value);
+                    try {
+                        Object result = InvokeNode.invokeUncached((PBuiltinFunction) reprFunction, userArgs);
+                        if (result instanceof String) {
+                            return (String) result;
+                        } else if (result instanceof PString) {
+                            return ((PString) result).getValue();
+                        } else {
+                            // This is illegal for a repr implementation, we ignore the result.
+                            // At this point it's probably difficult to report this properly.
+                        }
+                    } catch (PException e) {
+                        // Fall through to default
+                    }
+                }
+            }
         }
-        PBuiltinFunction reprMethod = (PBuiltinFunction) ((PBuiltinMethod) builtins.getAttribute(BuiltinNames.REPR)).getFunction();
-        Object[] userArgs = PArguments.create(2);
-        PArguments.setArgument(userArgs, 0, PNone.NONE);
-        PArguments.setArgument(userArgs, 1, value);
-        Object res = InvokeNode.create(reprMethod).execute(null, userArgs);
-        return res.toString();
+        // This is not a good place to report inconsistencies in any of the above conditions. Just
+        // return a String
+        return ((PythonAbstractObject) value).toString();
     }
 
     public static TruffleLogger getLogger() {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/PythonAbstractObject.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0
@@ -60,4 +60,9 @@ public void setNativeWrapper(DynamicObjectNativeWrapper nativeWrapper) {
         assert this.nativeWrapper == null;
         this.nativeWrapper = nativeWrapper;
     }
+
+    @Override
+    public String toString() {
+        return "<an abstract python object>";
+    }
 }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/call/InvokeNode.java

@@ -165,6 +165,7 @@ protected Object doNoKeywords(VirtualFrame frame, PythonObject globals, PCell[]
 }
 
 public abstract class InvokeNode extends AbstractInvokeNode {
+    private static final GenericInvokeNode UNCACHED = new GenericInvokeNode();
     @Child private DirectCallNode callNode;
     private final PythonObject globals;
     private final PCell[] closure;
@@ -199,6 +200,14 @@ public static InvokeNode create(PBuiltinFunction callee) {
         return InvokeNodeGen.create(callTarget, null, null, builtin, false);
     }
 
+    public static Object invokeUncached(PFunction callee, Object[] arguments) {
+        return UNCACHED.execute(null, callee, arguments);
+    }
+
+    public static Object invokeUncached(PBuiltinFunction callee, Object[] arguments) {
+        return UNCACHED.execute(null, callee, arguments);
+    }
+
     @Specialization
     protected Object doNoKeywords(VirtualFrame frame, Object[] arguments) {
         PArguments.setGlobals(arguments, globals);