Redirect comment links URIs without project

Change I4ccff233 introduced a regression in the comment links
URI without project.

A URI like `/c/test/+/1/comment/ff3303fd_8341647b/` would now
return a 404.

Handle it backend side the same way as any URIs without project.

Bug: Issue 306564466
Release-Notes: skip
Change-Id: Id06504eb88896fc52010a15e528f564d35d1918a
(cherry picked from commit 201e47b10fa90983171fe8819ea898048ea6223a)

3 files changed, 47 insertions, 2 deletions

diff --git a/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java b/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
index 77c53810ac..d9f1c09ee5 100644
--- a/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
+++ b/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
@@ -29,7 +29,17 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-/** Redirects {@code domain.tld/123} to {@code domain.tld/c/project/+/123}. */
+/**
+ * Redirects:
+ *
+ * <ul>
+ *   <li>{@code domain.tld/123} to {@code domain.tld/c/project/+/123}
+ *   <li/>
+ *   <li>{@code domain.tld/123/comment/bc630c55_3e265b44} to {@code
+ *       domain.tld/c/project/+/123/comment/bc630c55_3e265b44/}
+ *   <li/>
+ * </ul>
+ */
 @Singleton
 public class NumericChangeIdRedirectServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;
@@ -43,7 +53,11 @@ public class NumericChangeIdRedirectServlet extends HttpServlet {
 
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
-    String idString = req.getPathInfo();
+    String uriPath = req.getPathInfo();
+    // Check if we are processing a comment url, like "/c/1/comment/ff3303fd_8341647b/".
+    int commentIdx = uriPath.indexOf("/comment");
+    String idString = commentIdx == -1 ? uriPath : uriPath.substring(0, commentIdx);
+
     if (idString.endsWith("/")) {
       idString = idString.substring(0, idString.length() - 1);
     }
@@ -64,6 +78,10 @@ public class NumericChangeIdRedirectServlet extends HttpServlet {
     }
     String path =
         PageLinks.toChange(changeResource.getProject(), changeResource.getChange().getId());
+    if (commentIdx > -1) {
+      // path already contain a trailing /, hence we start from "commentIdx + 1"
+      path = path + uriPath.substring(commentIdx + 1);
+    }
     UrlModule.toGerrit(path, req, rsp);
   }
 }
diff --git a/java/com/google/gerrit/httpd/UrlModule.java b/java/com/google/gerrit/httpd/UrlModule.java
index 5a898a1189..aad6b57ad8 100644
--- a/java/com/google/gerrit/httpd/UrlModule.java
+++ b/java/com/google/gerrit/httpd/UrlModule.java
@@ -73,6 +73,7 @@ class UrlModule extends ServletModule {
     serveRegex("^/register$").with(registerScreen(false));
     serveRegex("^/register/(.+)$").with(registerScreen(true));
     serveRegex("^(?:/c)?/([1-9][0-9]*)/?$").with(NumericChangeIdRedirectServlet.class);
+    serveRegex("^(?:/c)?/([1-9][0-9]*)/comment/\\w+/?$").with(NumericChangeIdRedirectServlet.class);
     serveRegex("^/p/(.*)$").with(queryProjectNew());
     serveRegex("^/r/(.+)/?$").with(DirectChangeByCommit.class);
 
diff --git a/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java b/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
index 1143e893ba..0393f2b1c5 100644
--- a/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
@@ -436,6 +436,32 @@ public class RestApiServletIT extends AbstractDaemonTest {
   }
 
   @Test
+  public void testCommentLinkWithPrefixRedirects() throws Exception {
+    int changeNumber = createChange().getChange().getId().get();
+    String commentId = "ff3303fd_8341647b";
+
+    String redirectUri =
+        String.format("/c/%s/+/%d/comment/%s", project.get(), changeNumber, commentId);
+
+    anonymousRestSession
+        .get(String.format("/c/%s/comment/%s", changeNumber, commentId))
+        .assertTemporaryRedirect(redirectUri);
+  }
+
+  @Test
+  public void testCommentLinkWithoutPrefixRedirects() throws Exception {
+    int changeNumber = createChange().getChange().getId().get();
+    String commentId = "ff3303fd_8341647b";
+
+    String redirectUri =
+        String.format("/c/%s/+/%d/comment/%s", project.get(), changeNumber, commentId);
+
+    anonymousRestSession
+        .get(String.format("/%s/comment/%s", changeNumber, commentId))
+        .assertTemporaryRedirect(redirectUri);
+  }
+
+  @Test
   public void testNumericChangeIdRedirectWithoutPrefix() throws Exception {
     int changeNumber = createChange().getChange().getId().get();