Make gerrit's HttpServletRequest and HttpServletResponse visible to http plugins

Introduce a @RootRelative annotation for plugins to use to request the
HttpServletRequest and HttpServletResponse from gerrit.

The annotation distinguishes these request and response objects from
those injected by guice's ServletModule when http plugins are handling
a request.

This is needed to eventually allow plugins to replace gerrit's
WebSession implementation.

Change-Id: Idc8c248540deadb10644aca9a1ad92d28e07aad3

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/annotations/RootRelative.java

@@ -0,0 +1,37 @@
+// Copyright (C) 2014 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.annotations;
+
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.inject.BindingAnnotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation applied to HttpServletRequest and HttpServletResponse
+ * when they are inherited from Gerrit instead of being injected by
+ * a plugin's ServletModule.  This means that the path returned by
+ * {@link javax.servlet.http.HttpServletRequest#getPathInfo} is
+ * relative to the Gerrit root instead of a path within the plugin's
+ * URL space.
+ */
+@Target({ElementType.PARAMETER, ElementType.FIELD})
+@Retention(RUNTIME)
+@BindingAnnotation
+public @interface RootRelative {
+}

gerrit-server/BUCK

@@ -47,6 +47,7 @@ java_library2(
     '//lib:parboiled-core',
     '//lib:pegdown',
     '//lib:protobuf',
+    '//lib:servlet-api-3_1',
     '//lib:velocity',
     '//lib/antlr:java_runtime',
     '//lib/commons:codec',

gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java

@@ -24,6 +24,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
+import com.google.gerrit.extensions.annotations.RootRelative;
 import com.google.gerrit.extensions.events.LifecycleListener;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.extensions.registration.DynamicMap;
@@ -56,6 +57,8 @@ import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.inject.Inject;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
 /**
  * Tracks Guice bindings that should be exposed to loaded plugins.
@@ -501,6 +504,12 @@ public class PluginGuiceEnvironment {
     bindings.remove(Key.get(Injector.class));
     bindings.remove(Key.get(java.util.logging.Logger.class));
 
+    final @Nullable Binding<HttpServletRequest> requestBinding =
+        src.getExistingBinding(Key.get(HttpServletRequest.class));
+
+    final @Nullable Binding<HttpServletResponse> responseBinding =
+        src.getExistingBinding(Key.get(HttpServletResponse.class));
+
     return new AbstractModule() {
       @SuppressWarnings("unchecked")
       @Override
@@ -510,6 +519,17 @@ public class PluginGuiceEnvironment {
           Binding<Object> b = (Binding<Object>) e.getValue();
           bind(k).toProvider(b.getProvider());
         }
+
+        if (requestBinding != null) {
+          bind(HttpServletRequest.class)
+              .annotatedWith(RootRelative.class)
+              .toProvider(requestBinding.getProvider());
+        }
+        if (responseBinding != null) {
+          bind(HttpServletResponse.class)
+              .annotatedWith(RootRelative.class)
+              .toProvider(responseBinding.getProvider());
+        }
       }
     };
   }