[web_engine] Fix leading slash issue with ContentDirectoryProvider.

The use of leading slashes causes path validation issues in VFS
implementations like vfs::PseudoDir.

This fixes the issue by discarding the leading slash from the path
component of requested URLs.

Adds a browser test which validates the use of PseudoDir and VfsFile
with ContentDirectoryProvider.

Bug: 1011180
Change-Id: I2b47ad35023be73cc32538f83b166ebaa9b85f9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1848411
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Auto-Submit: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704829}

fuchsia/engine/browser/content_directory_browsertest.cc

@@ -3,14 +3,18 @@
 // found in the LICENSE file.
 
 #include <lib/fdio/directory.h>
+#include <lib/vfs/cpp/pseudo_dir.h>
+#include <lib/vfs/cpp/vmo_file.h>
 
 #include "fuchsia/engine/test/web_engine_browser_test.h"
 
 #include "base/files/file_path.h"
+#include "base/files/file_util.h"
 #include "base/fuchsia/fuchsia_logging.h"
 #include "base/path_service.h"
 #include "base/test/bind_test_util.h"
 #include "base/test/test_timeouts.h"
+#include "base/threading/thread_restrictions.h"
 #include "fuchsia/base/frame_test_util.h"
 #include "fuchsia/base/test_navigation_listener.h"
 #include "fuchsia/engine/browser/content_directory_loader_factory.h"
@@ -147,6 +151,53 @@ IN_PROC_BROWSER_TEST_F(ContentDirectoryTest, ImgSubresource) {
   navigation_listener_.RunUntilUrlAndTitleEquals(kUrl, "image fetched");
 }
 
+// Reads content sourced from VFS PseudoDirs and VmoFiles.
+IN_PROC_BROWSER_TEST_F(ContentDirectoryTest, FromVfsPseudoDir) {
+  base::ScopedAllowBlockingForTesting allow_block;
+
+  // Get the file contents and store it in a VMO.
+  std::string contents;
+  base::FilePath pkg_path;
+  base::PathService::Get(base::DIR_ASSETS, &pkg_path);
+  ASSERT_TRUE(base::ReadFileToString(
+      pkg_path.AppendASCII("fuchsia/engine/test/data/title1.html"), &contents));
+  zx::vmo contents_vmo;
+  zx_status_t status = zx::vmo::create(contents.size(), 0, &contents_vmo);
+  ASSERT_EQ(status, ZX_OK);
+  status = contents_vmo.write(contents.data(), 0, contents.size());
+  ASSERT_EQ(status, ZX_OK);
+
+  // Build up the directory structure of a VmoFile inside a PseudoDir.
+  auto vmo_file = std::make_unique<vfs::VmoFile>(
+      std::move(contents_vmo), 0, contents.size(),
+      vfs::VmoFile::WriteOption::READ_ONLY, vfs::VmoFile::Sharing::CLONE_COW);
+  vfs::PseudoDir pseudo_dir;
+  status = pseudo_dir.AddEntry("title1.html", std::move(vmo_file));
+  ASSERT_EQ(status, ZX_OK);
+
+  // Serve the PseudoDir under the "pseudo-dir" URL.
+  fuchsia::web::ContentDirectoryProvider provider;
+  provider.set_name("pseudo-dir");
+  fidl::InterfaceHandle<fuchsia::io::Directory> directory_channel;
+  pseudo_dir.Serve(
+      fuchsia::io::OPEN_FLAG_DIRECTORY | fuchsia::io::OPEN_RIGHT_READABLE,
+      directory_channel.NewRequest().TakeChannel());
+  provider.set_directory(std::move(directory_channel));
+  std::vector<fuchsia::web::ContentDirectoryProvider> providers;
+  providers.emplace_back(std::move(provider));
+  ContentDirectoryLoaderFactory::SetContentDirectoriesForTest(
+      std::move(providers));
+
+  // Access the VmoFile under the PseudoDir.
+  const GURL kUrl("fuchsia-dir://pseudo-dir/title1.html");
+  fuchsia::web::FramePtr frame = CreateFrame();
+  fuchsia::web::NavigationControllerPtr controller;
+  frame->GetNavigationController(controller.NewRequest());
+  EXPECT_TRUE(cr_fuchsia::LoadUrlAndExpectResponse(
+      controller.get(), fuchsia::web::LoadUrlParams(), kUrl.spec()));
+  navigation_listener_.RunUntilUrlAndTitleEquals(kUrl, "title 1");
+}
+
 // Verify that resource providers are origin-isolated.
 IN_PROC_BROWSER_TEST_F(ContentDirectoryTest, ScriptSrcCrossOriginBlocked) {
   const GURL kUrl("fuchsia-dir://testdata/cross_origin_include_script.html");

fuchsia/engine/browser/content_directory_loader_factory.cc

@@ -335,10 +335,23 @@ void ContentDirectoryLoaderFactory::CreateLoaderAndStart(
     return;
   }
 
+  std::string requested_path = request.url.path();
+  if (requested_path.empty()) {
+    client->OnComplete(
+        network::URLLoaderCompletionStatus(net::ERR_INVALID_URL));
+    return;
+  }
+
+  // Not all VFS implementations handle leading slashes in the same way, so
+  // remove it for maximum compatibility.
+  // TODO(fxb/38339): Update this comment when issue is resolved.
+  if (requested_path[0] == '/')
+    requested_path = requested_path.substr(1, requested_path.size() - 1);
+
   fidl::InterfaceHandle<fuchsia::io::Node> file_handle;
-  net::Error open_result = OpenFileFromDirectory(
-      request.url.GetOrigin().host(), base::FilePath(request.url.path()),
-      file_handle.NewRequest());
+  net::Error open_result = OpenFileFromDirectory(request.url.GetOrigin().host(),
+                                                 base::FilePath(requested_path),
+                                                 file_handle.NewRequest());
   if (open_result != net::OK) {
     client->OnComplete(network::URLLoaderCompletionStatus(open_result));
     return;
@@ -351,7 +364,7 @@ void ContentDirectoryLoaderFactory::CreateLoaderAndStart(
   fidl::InterfaceHandle<fuchsia::io::Node> metadata_handle;
   open_result =
       OpenFileFromDirectory(request.url.GetOrigin().host(),
-                            base::FilePath(request.url.path() + "._metadata"),
+                            base::FilePath(requested_path + "._metadata"),
                             metadata_handle.NewRequest());
   if (open_result != net::OK) {
     client->OnComplete(network::URLLoaderCompletionStatus(open_result));