XWIKI-21553: Do not override existing documents on user action (#2790)

* Introduce a new listener to cancel any save that would delete the document.
* Add a unit test.

xwiki-platform-core/xwiki-platform-oldcore/src/main/java/org/xwiki/internal/document/DocumentOverrideListener.java

@@ -0,0 +1,77 @@
+/*
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.xwiki.internal.document;
+
+import javax.inject.Named;
+import javax.inject.Singleton;
+
+import org.xwiki.component.annotation.Component;
+import org.xwiki.observation.AbstractEventListener;
+import org.xwiki.observation.event.CancelableEvent;
+import org.xwiki.observation.event.Event;
+
+import com.xpn.xwiki.doc.XWikiDocument;
+import com.xpn.xwiki.internal.event.UserUpdatingDocumentEvent;
+
+/**
+ * Cancel any save that tries to save a new document if the document already exists.
+ *
+ * <p>
+ *     This can happen when the context document is set to an empty document because the user doesn't have view right,
+ *     but the user still has, e.g., edit right. In this situation, the user would still be able to to save but it is
+ *     hard to imagine a scenario where this would make sense. This listener therefore cancels the save in this
+ *     situation.
+ * </p>
+ *
+ * @version $Id$
+ * @since 14.10.21
+ * @since 15.5.5
+ * @since 15.10.6
+ */
+@Component
+@Singleton
+@Named(DocumentOverrideListener.NAME)
+public class DocumentOverrideListener extends AbstractEventListener
+{
+    /**
+     * The unique identifier of the listener.
+     */
+    public static final String NAME = "org.xwiki.internal.document.DocumentOverrideListener";
+
+    /**
+     * The default constructor.
+     */
+    public DocumentOverrideListener()
+    {
+        super(NAME, new UserUpdatingDocumentEvent());
+    }
+
+    @Override
+    public void onEvent(Event event, Object source, Object data)
+    {
+        XWikiDocument document = (XWikiDocument) source;
+        XWikiDocument originalDocument = document.getOriginalDocument();
+
+        if (document.isNew() && originalDocument != null && !originalDocument.isNew()) {
+            ((CancelableEvent) event).cancel(
+                "The document already exists but the document to be saved is marked as new.");
+        }
+    }
+}

xwiki-platform-core/xwiki-platform-oldcore/src/main/resources/META-INF/components.txt

@@ -278,3 +278,4 @@ org.xwiki.security.authservice.script.AuthServiceScriptService
 org.xwiki.model.validation.edit.XWikiDocumentLockEditConfirmationChecker
 org.xwiki.evaluation.internal.DefaultObjectEvaluator
 org.xwiki.evaluation.internal.VelocityObjectPropertyEvaluator
+org.xwiki.internal.document.DocumentOverrideListener

xwiki-platform-core/xwiki-platform-oldcore/src/test/java/org/xwiki/internal/document/DocumentOverrideListenerTest.java

@@ -0,0 +1,86 @@
+/*
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.xwiki.internal.document;
+
+import org.junit.jupiter.api.Test;
+import org.xwiki.model.reference.DocumentReference;
+import org.xwiki.observation.internal.DefaultObservationManager;
+import org.xwiki.test.annotation.ComponentList;
+
+import com.xpn.xwiki.XWikiException;
+import com.xpn.xwiki.doc.XWikiDocument;
+import com.xpn.xwiki.test.MockitoOldcore;
+import com.xpn.xwiki.test.junit5.mockito.InjectMockitoOldcore;
+import com.xpn.xwiki.test.junit5.mockito.OldcoreTest;
+import com.xpn.xwiki.test.reference.ReferenceComponentList;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Unit tests for {@link DocumentOverrideListener}.
+ *
+ * @version $Id$
+ */
+@OldcoreTest(mockXWiki = false)
+@ReferenceComponentList
+@ComponentList({ DefaultObservationManager.class, DocumentOverrideListener.class })
+class DocumentOverrideListenerTest
+{
+    @InjectMockitoOldcore
+    private MockitoOldcore oldcore;
+
+    @Test
+    void savingNewDocument() throws Exception
+    {
+        DocumentReference documentReference = new DocumentReference("wiki", "space", "page");
+        XWikiDocument document = new XWikiDocument(documentReference);
+        this.oldcore.getSpyXWiki().checkSavingDocument(mock(), document, this.oldcore.getXWikiContext());
+    }
+
+    @Test
+    void savingExistingDocument() throws Exception
+    {
+        DocumentReference documentReference = new DocumentReference("wiki", "space", "page");
+        XWikiDocument document = new XWikiDocument(documentReference);
+        this.oldcore.getSpyXWiki().saveDocument(document, this.oldcore.getXWikiContext());
+        document = this.oldcore.getSpyXWiki().getDocument(documentReference, this.oldcore.getXWikiContext());
+        assertFalse(document.isNew());
+        this.oldcore.getSpyXWiki().checkSavingDocument(mock(), document, this.oldcore.getXWikiContext());
+    }
+
+    @Test
+    void savingOverridingExistingDocument() throws Exception
+    {
+        DocumentReference documentReference = new DocumentReference("wiki", "space", "page");
+        DocumentReference userReference = new DocumentReference("wiki", "XWiki", "user");
+        XWikiDocument document = new XWikiDocument(documentReference);
+        this.oldcore.getSpyXWiki().saveDocument(document, this.oldcore.getXWikiContext());
+        XWikiDocument newDocument = new XWikiDocument(documentReference);
+        XWikiException exception = assertThrows(XWikiException.class,
+            () -> this.oldcore.getSpyXWiki()
+                .checkSavingDocument(userReference, newDocument, this.oldcore.getXWikiContext()));
+        assertEquals("Error number 9001 in 9: User [wiki:XWiki.user] has been denied the right to save the "
+            + "document [wiki:space.page]. Reason: [The document already exists but the document to be saved is marked "
+            + "as new.]", exception.getMessage());
+    }
+}