Revert of [Service Manager] Get rid of dynamic service discovery

services/catalog/reader.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "services/catalog/reader.h"
+
+#include "base/base_paths.h"
+#include "base/bind.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_util.h"
+#include "base/json/json_file_value_serializer.h"
+#include "base/json/json_reader.h"
+#include "base/memory/ptr_util.h"
+#include "base/path_service.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/task_runner_util.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "base/values.h"
+#include "services/catalog/constants.h"
+#include "services/catalog/entry.h"
+#include "services/catalog/entry_cache.h"
+#include "services/catalog/manifest_provider.h"
+#include "services/catalog/public/interfaces/constants.mojom.h"
+#include "services/service_manager/public/interfaces/constants.mojom.h"
+
+namespace catalog {
+namespace {
+
+#if defined(OS_WIN)
+const char kServiceExecutableExtension[] = ".service.exe";
+#else
+const char kServiceExecutableExtension[] = ".service";
+#endif
+
+const char kCatalogServicesKey[] = "services";
+const char kCatalogServiceEmbeddedKey[] = "embedded";
+const char kCatalogServiceExecutableKey[] = "executable";
+const char kCatalogServiceManifestKey[] = "manifest";
+
+base::FilePath GetManifestPath(const base::FilePath& package_dir,
+                               const std::string& name,
+                               const std::string& package_name_override) {
+  // TODO(beng): think more about how this should be done for exe targets.
+  std::string package_name =
+      package_name_override.empty() ? name : package_name_override;
+  return package_dir.AppendASCII(kPackagesDirName).AppendASCII(
+      package_name + "/manifest.json");
+}
+
+base::FilePath GetExecutablePath(const base::FilePath& package_dir,
+                                 const std::string& name) {
+  return package_dir.AppendASCII(
+      name + "/" + name + kServiceExecutableExtension);
+}
+
+std::unique_ptr<Entry> ProcessManifest(const base::Value* manifest_root,
+                                       const base::FilePath& package_dir,
+                                       const base::FilePath& executable_path) {
+
+  // Manifest was malformed or did not exist.
+  if (!manifest_root)
+    return nullptr;
+
+  const base::DictionaryValue* dictionary = nullptr;
+  if (!manifest_root->GetAsDictionary(&dictionary))
+    return nullptr;
+
+  std::unique_ptr<Entry> entry = Entry::Deserialize(*dictionary);
+  if (!entry)
+    return nullptr;
+  if (!executable_path.empty())
+    entry->set_path(executable_path);
+  else
+    entry->set_path(GetExecutablePath(package_dir, entry->name()));
+  return entry;
+}
+
+std::unique_ptr<Entry> ProcessUniqueManifest(
+    std::unique_ptr<base::Value> manifest_root,
+    const base::FilePath& package_dir) {
+  return ProcessManifest(manifest_root.get(), package_dir, base::FilePath());
+}
+
+std::unique_ptr<Entry> CreateEntryForManifestAt(
+    const base::FilePath& manifest_path,
+    const base::FilePath& package_dir) {
+  JSONFileValueDeserializer deserializer(manifest_path);
+  int error = 0;
+  std::string message;
+
+  // TODO(beng): probably want to do more detailed error checking. This should
+  //             be done when figuring out if to unblock connection completion.
+  return ProcessUniqueManifest(deserializer.Deserialize(&error, &message),
+                               package_dir);
+}
+
+void ScanDir(
+    const base::FilePath& package_dir,
+    const Reader::ReadManifestCallback& read_manifest_callback,
+    scoped_refptr<base::SingleThreadTaskRunner> original_thread_task_runner,
+    const base::Closure& read_complete_closure) {
+  base::FileEnumerator enumerator(package_dir, false,
+                                  base::FileEnumerator::DIRECTORIES);
+  while (1) {
+    base::FilePath path = enumerator.Next();
+    if (path.empty())
+      break;
+    base::FilePath manifest_path = path.AppendASCII("manifest.json");
+    std::unique_ptr<Entry> entry =
+        CreateEntryForManifestAt(manifest_path, package_dir);
+    if (!entry)
+      continue;
+
+    // Skip over subdirs that contain only manifests, they're artifacts of the
+    // build (e.g. for applications that are packaged into others) and are not
+    // valid standalone packages.
+    base::FilePath package_path = GetExecutablePath(package_dir, entry->name());
+    if (entry->name() != service_manager::mojom::kServiceName &&
+        entry->name() != catalog::mojom::kServiceName &&
+        !base::PathExists(package_path)) {
+      continue;
+    }
+
+    original_thread_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(read_manifest_callback, base::Passed(&entry)));
+  }
+
+  original_thread_task_runner->PostTask(FROM_HERE, read_complete_closure);
+}
+
+std::unique_ptr<Entry> ReadManifest(
+    const base::FilePath& package_dir,
+    const std::string& mojo_name,
+    const std::string& package_name_override,
+    const base::FilePath& manifest_path_override) {
+  base::FilePath manifest_path;
+  if (manifest_path_override.empty()) {
+    manifest_path =
+        GetManifestPath(package_dir, mojo_name, package_name_override);
+  } else {
+    manifest_path = manifest_path_override;
+  }
+
+  std::unique_ptr<Entry> entry = CreateEntryForManifestAt(manifest_path,
+                                                          package_dir);
+  if (!entry) {
+    entry.reset(new Entry(mojo_name));
+    entry->set_path(GetExecutablePath(
+        package_dir.AppendASCII(kPackagesDirName), mojo_name));
+  }
+  return entry;
+}
+
+void IgnoreResolveResult(service_manager::mojom::ResolveResultPtr,
+                         service_manager::mojom::ResolveResultPtr) {}
+
+void LoadCatalogManifestIntoCache(const base::Value* root,
+                                  const base::FilePath& package_dir,
+                                  EntryCache* cache) {
+  DCHECK(root);
+  const base::DictionaryValue* catalog = nullptr;
+  if (!root->GetAsDictionary(&catalog)) {
+    LOG(ERROR) << "Catalog manifest is not a dictionary value.";
+    return;
+  }
+  DCHECK(catalog);
+
+  const base::DictionaryValue* services = nullptr;
+  if (!catalog->GetDictionary(kCatalogServicesKey, &services)) {
+    LOG(ERROR) << "Catalog manifest \"services\" is not a dictionary value.";
+    return;
+  }
+
+  for (base::DictionaryValue::Iterator it(*services); !it.IsAtEnd();
+       it.Advance()) {
+    const base::DictionaryValue* service_entry = nullptr;
+    if (!it.value().GetAsDictionary(&service_entry)) {
+      LOG(ERROR) << "Catalog service entry for \"" << it.key()
+                 << "\" is not a dictionary value.";
+      continue;
+    }
+
+    bool is_embedded = false;
+    service_entry->GetBoolean(kCatalogServiceEmbeddedKey, &is_embedded);
+
+    base::FilePath executable_path;
+    std::string executable_path_string;
+    if (service_entry->GetString(kCatalogServiceExecutableKey,
+                                 &executable_path_string)) {
+      base::FilePath exe_dir;
+      CHECK(base::PathService::Get(base::DIR_EXE, &exe_dir));
+#if defined(OS_WIN)
+      executable_path_string += ".exe";
+      base::ReplaceFirstSubstringAfterOffset(
+          &executable_path_string, 0, "@EXE_DIR",
+          base::UTF16ToUTF8(exe_dir.value()));
+      executable_path =
+          base::FilePath(base::UTF8ToUTF16(executable_path_string));
+#else
+      base::ReplaceFirstSubstringAfterOffset(
+          &executable_path_string, 0, "@EXE_DIR", exe_dir.value());
+      executable_path = base::FilePath(executable_path_string);
+#endif
+    }
+
+    const base::DictionaryValue* manifest = nullptr;
+    if (!service_entry->GetDictionary(kCatalogServiceManifestKey, &manifest)) {
+      LOG(ERROR) << "Catalog entry for \"" << it.key() << "\" has an invalid "
+                 << "\"manifest\" value.";
+      continue;
+    }
+
+    DCHECK(!(is_embedded && !executable_path.empty()));
+
+    auto entry = ProcessManifest(
+        manifest, is_embedded ? base::FilePath() : package_dir,
+        executable_path);
+    if (entry) {
+      bool added = cache->AddRootEntry(std::move(entry));
+      DCHECK(added);
+    } else {
+      LOG(ERROR) << "Failed to read manifest entry for \"" << it.key() << "\".";
+    }
+  }
+}
+
+}  // namespace
+
+Reader::Reader(std::unique_ptr<base::Value> static_manifest,
+               EntryCache* cache)
+    : using_static_catalog_(true),
+      manifest_provider_(nullptr),
+      weak_factory_(this) {
+  PathService::Get(base::DIR_MODULE, &system_package_dir_);
+  LoadCatalogManifestIntoCache(
+      static_manifest.get(), system_package_dir_.AppendASCII(kPackagesDirName),
+      cache);
+}
+
+// A sequenced task runner is used to guarantee requests are serviced in the
+// order requested. To do otherwise means we may run callbacks in an
+// unpredictable order, leading to flake.
+Reader::Reader(base::SequencedWorkerPool* worker_pool,
+               ManifestProvider* manifest_provider)
+    : Reader(manifest_provider) {
+  file_task_runner_ = worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
+      base::SequencedWorkerPool::GetSequenceToken(),
+      base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+}
+
+Reader::Reader(base::SingleThreadTaskRunner* task_runner,
+               ManifestProvider* manifest_provider)
+    : Reader(manifest_provider) {
+  file_task_runner_ = task_runner;
+}
+
+Reader::~Reader() {}
+
+void Reader::Read(const base::FilePath& package_dir,
+                  EntryCache* cache,
+                  const base::Closure& read_complete_closure) {
+  file_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ScanDir, package_dir,
+                 base::Bind(&Reader::OnReadManifest, weak_factory_.GetWeakPtr(),
+                            cache, base::Bind(&IgnoreResolveResult)),
+                 base::ThreadTaskRunnerHandle::Get(),
+                 read_complete_closure));
+}
+
+void Reader::CreateEntryForName(
+    const std::string& name,
+    EntryCache* cache,
+    const CreateEntryForNameCallback& entry_created_callback) {
+  if (manifest_provider_) {
+    std::unique_ptr<base::Value> manifest_root =
+        manifest_provider_->GetManifest(name);
+    if (manifest_root) {
+      base::PostTaskAndReplyWithResult(
+          file_task_runner_.get(), FROM_HERE,
+          base::Bind(&ProcessUniqueManifest, base::Passed(&manifest_root),
+                     system_package_dir_),
+          base::Bind(&Reader::OnReadManifest, weak_factory_.GetWeakPtr(), cache,
+                     entry_created_callback));
+      return;
+    }
+  } else if (using_static_catalog_) {
+    // A Reader using a static catalog manifest does not support dynamic
+    // discovery or introduction of new catalog entries.
+    entry_created_callback.Run(service_manager::mojom::ResolveResultPtr(),
+                               service_manager::mojom::ResolveResultPtr());
+    return;
+  }
+
+  base::FilePath manifest_path_override;
+  {
+    auto override_iter = manifest_path_overrides_.find(name);
+    if (override_iter != manifest_path_overrides_.end())
+      manifest_path_override = override_iter->second;
+  }
+
+  std::string package_name_override;
+  {
+    auto override_iter = package_name_overrides_.find(name);
+    if (override_iter != package_name_overrides_.end())
+      package_name_override = override_iter->second;
+  }
+  base::PostTaskAndReplyWithResult(
+      file_task_runner_.get(), FROM_HERE,
+      base::Bind(&ReadManifest, system_package_dir_, name,
+                 package_name_override, manifest_path_override),
+      base::Bind(&Reader::OnReadManifest, weak_factory_.GetWeakPtr(), cache,
+                  entry_created_callback));
+}
+
+void Reader::OverridePackageName(const std::string& service_name,
+                                 const std::string& package_name) {
+  package_name_overrides_.insert(std::make_pair(service_name, package_name));
+}
+
+void Reader::OverrideManifestPath(const std::string& service_name,
+                                  const base::FilePath& path) {
+  manifest_path_overrides_.insert(std::make_pair(service_name, path));
+}
+
+Reader::Reader(ManifestProvider* manifest_provider)
+    : using_static_catalog_(false),
+      manifest_provider_(manifest_provider),
+      weak_factory_(this) {
+  PathService::Get(base::DIR_MODULE, &system_package_dir_);
+}
+
+void Reader::OnReadManifest(
+    EntryCache* cache,
+    const CreateEntryForNameCallback& entry_created_callback,
+    std::unique_ptr<Entry> entry) {
+  if (!entry)
+    return;
+
+  std::string name = entry->name();
+  cache->AddRootEntry(std::move(entry));
+
+  // NOTE: It's currently possible to end up with a duplicate entry, in which
+  // case the above call to AddRootEntry() may actually discard |entry|. We
+  // therefore look up the Entry by name here to get resolution metadata.
+
+  const Entry* resolved_entry = cache->GetEntry(name);
+  DCHECK(resolved_entry);
+  entry_created_callback.Run(
+      service_manager::mojom::ResolveResult::From(resolved_entry),
+      service_manager::mojom::ResolveResult::From(resolved_entry->parent()));
+}
+
+}  // namespace catalog