Refactor RequestUtil into a separate package

Move RequestUtil into its own package. This facilitates
reuse of request attribute accessor methods by external
libraries.

Change-Id: Id002eb4f72827d65087a999adbd2ba9a58795fe2

gerrit-util-http/src/main/java/com/google/gerrit/util/http/RequestUtil.java

@@ -0,0 +1,60 @@
+// 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.util.http;
+
+import javax.servlet.http.HttpServletRequest;
+
+/** Utilities for manipulating HTTP request objects. */
+public class RequestUtil {
+  /** HTTP request attribute for storing the Throwable that caused an error condition. */
+  private static final String ATTRIBUTE_ERROR_TRACE =
+      RequestUtil.class.getName() + "/ErrorTraceThrowable";
+
+  public static void setErrorTraceAttribute(HttpServletRequest req, Throwable t) {
+    req.setAttribute(ATTRIBUTE_ERROR_TRACE, t);
+  }
+
+  public static Throwable getErrorTraceAttribute(HttpServletRequest req) {
+    return (Throwable) req.getAttribute(ATTRIBUTE_ERROR_TRACE);
+  }
+
+  /**
+   * @return the same value as {@link HttpServletRequest#getPathInfo()}, but
+   *     without decoding URL-encoded characters.
+   */
+  public static String getEncodedPathInfo(HttpServletRequest req) {
+    // Based on com.google.guice.ServletDefinition$1#getPathInfo() from:
+    // https://github.com/google/guice/blob/41c126f99d6309886a0ded2ac729033d755e1593/extensions/servlet/src/com/google/inject/servlet/ServletDefinition.java
+    String servletPath = req.getServletPath();
+    int servletPathLength = servletPath.length();
+    String requestUri = req.getRequestURI();
+    String pathInfo = requestUri.substring(req.getContextPath().length())
+        .replaceAll("[/]{2,}", "/");
+    if (pathInfo.startsWith(servletPath)) {
+      pathInfo = pathInfo.substring(servletPathLength);
+      // Corner case: when servlet path & request path match exactly (without
+      // trailing '/'), then pathinfo is null.
+      if (pathInfo.isEmpty() && servletPathLength > 0) {
+        pathInfo = null;
+      }
+    } else {
+      pathInfo = null;
+    }
+    return pathInfo;
+  }
+
+  private RequestUtil() {
+  }
+}

gerrit-util-http/src/test/java/com/google/gerrit/util/http/RequestUtilTest.java

@@ -0,0 +1,91 @@
+// 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.util.http;
+
+import static org.easymock.EasyMock.createMock;
+import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.replay;
+import static org.easymock.EasyMock.verify;
+import static org.junit.Assert.assertEquals;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+
+public class RequestUtilTest {
+  private List<Object> mocks;
+
+  @Before
+  public void setUp() {
+    mocks = Collections.synchronizedList(new ArrayList<>());
+  }
+
+  @After
+  public void tearDown() {
+    for (Object mock : mocks) {
+      verify(mock);
+    }
+  }
+
+  @Test
+  public void emptyContextPath() {
+    assertEquals("/foo/bar", RequestUtil.getEncodedPathInfo(
+        mockRequest("/s/foo/bar", "", "/s")));
+    assertEquals("/foo%2Fbar", RequestUtil.getEncodedPathInfo(
+        mockRequest("/s/foo%2Fbar", "", "/s")));
+  }
+
+  @Test
+  public void emptyServletPath() {
+    assertEquals("/foo/bar", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/foo/bar", "/c", "")));
+    assertEquals("/foo%2Fbar", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/foo%2Fbar", "/c", "")));
+  }
+
+  @Test
+  public void trailingSlashes() {
+    assertEquals("/foo/bar/", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/s/foo/bar/", "/c", "/s")));
+    assertEquals("/foo/bar/", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/s/foo/bar///", "/c", "/s")));
+    assertEquals("/foo%2Fbar/", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/s/foo%2Fbar/", "/c", "/s")));
+    assertEquals("/foo%2Fbar/", RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/s/foo%2Fbar///", "/c", "/s")));
+  }
+
+  @Test
+  public void servletPathMatchesRequestPath() {
+    assertEquals(null, RequestUtil.getEncodedPathInfo(
+        mockRequest("/c/s", "/c", "/s")));
+  }
+
+  private HttpServletRequest mockRequest(String uri, String contextPath, String servletPath) {
+    HttpServletRequest req = createMock(HttpServletRequest.class);
+    expect(req.getRequestURI()).andStubReturn(uri);
+    expect(req.getContextPath()).andStubReturn(contextPath);
+    expect(req.getServletPath()).andStubReturn(servletPath);
+    replay(req);
+    mocks.add(req);
+    return req;
+  }
+}