Don't parse non-existing files in files REST collections

For non-existing members REST collections are expected to throw
ResourceNotFoundException.

Change-Id: I97680b9fc17d0348aef1a5926f73c7e948737e07
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/project/FileResource.java

@@ -14,16 +14,39 @@
 
 package com.google.gerrit.server.project;
 
+import com.google.gerrit.extensions.restapi.IdString;
+import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestResource;
 import com.google.gerrit.extensions.restapi.RestView;
+import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.inject.TypeLiteral;
 
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevTree;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.treewalk.TreeWalk;
+
+import java.io.IOException;
 
 public class FileResource implements RestResource {
   public static final TypeLiteral<RestView<FileResource>> FILE_KIND =
       new TypeLiteral<RestView<FileResource>>() {};
 
+  public static FileResource create(GitRepositoryManager repoManager,
+      ProjectControl project, ObjectId rev, String path)
+          throws ResourceNotFoundException, IOException {
+    try (Repository repo =
+            repoManager.openRepository(project.getProject().getNameKey());
+        RevWalk rw = new RevWalk(repo)) {
+      RevTree tree = rw.parseTree(rev);
+      if (TreeWalk.forPath(repo, path, tree) != null) {
+        return new FileResource(project, rev, path);
+      }
+    }
+    throw new ResourceNotFoundException(IdString.fromDecoded(path));
+  }
+
   private final ProjectControl project;
   private final ObjectId rev;
   private final String path;

gerrit-server/src/main/java/com/google/gerrit/server/project/FilesCollection.java

@@ -19,19 +19,25 @@ import com.google.gerrit.extensions.restapi.ChildCollection;
 import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestView;
+import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 
 import org.eclipse.jgit.lib.ObjectId;
 
+import java.io.IOException;
+
 @Singleton
 public class FilesCollection implements
     ChildCollection<BranchResource, FileResource> {
   private final DynamicMap<RestView<FileResource>> views;
+  private final GitRepositoryManager repoManager;
 
   @Inject
-  FilesCollection(DynamicMap<RestView<FileResource>> views) {
+  FilesCollection(DynamicMap<RestView<FileResource>> views,
+      GitRepositoryManager repoManager) {
     this.views = views;
+    this.repoManager = repoManager;
   }
 
   @Override
@@ -40,11 +46,10 @@ public class FilesCollection implements
   }
 
   @Override
-  public FileResource parse(BranchResource parent, IdString id) {
-    return new FileResource(
-        parent.getControl(),
-        ObjectId.fromString(parent.getRevision()),
-        id.get());
+  public FileResource parse(BranchResource parent, IdString id)
+      throws ResourceNotFoundException, IOException {
+    return FileResource.create(repoManager, parent.getControl(),
+        ObjectId.fromString(parent.getRevision()), id.get());
   }
 
   @Override

gerrit-server/src/main/java/com/google/gerrit/server/project/FilesInCommitCollection.java

@@ -19,17 +19,23 @@ import com.google.gerrit.extensions.restapi.ChildCollection;
 import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestView;
+import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 
+import java.io.IOException;
+
 @Singleton
 public class FilesInCommitCollection implements
     ChildCollection<CommitResource, FileResource> {
   private final DynamicMap<RestView<FileResource>> views;
+  private final GitRepositoryManager repoManager;
 
   @Inject
-  FilesInCommitCollection(DynamicMap<RestView<FileResource>> views) {
+  FilesInCommitCollection(DynamicMap<RestView<FileResource>> views,
+      GitRepositoryManager repoManager) {
     this.views = views;
+    this.repoManager = repoManager;
   }
 
   @Override
@@ -39,8 +45,9 @@ public class FilesInCommitCollection implements
 
   @Override
   public FileResource parse(CommitResource parent, IdString id)
-      throws ResourceNotFoundException {
-    return new FileResource(parent.getProject(), parent.getCommit(), id.get());
+      throws ResourceNotFoundException, IOException {
+    return FileResource.create(repoManager, parent.getProject(),
+        parent.getCommit(), id.get());
   }
 
   @Override