Extract external file systems handling from isolated context.

webkit/fileapi/external_mount_points.cc

+// Copyright (c) 2013 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 "webkit/fileapi/external_mount_points.h"
+
+#include "base/file_path.h"
+#include "base/lazy_instance.h"
+#include "base/path_service.h"
+#include "base/stl_util.h"
+#include "webkit/fileapi/remote_file_system_proxy.h"
+
+namespace {
+
+// Normalizes file path so it has normalized separators and ends with exactly
+// one separator. Paths have to be normalized this way for use in
+// GetVirtualPath method. Separators cannot be completely stripped, or
+// GetVirtualPath could not working in some edge cases.
+// For example, /a/b/c(1)/d would be erroneously resolved as c/d if the
+// following mount points were registered: "/a/b/c", "/a/b/c(1)". (Note:
+// "/a/b/c" < "/a/b/c(1)" < "/a/b/c/").
+FilePath NormalizeFilePath(const FilePath& path) {
+  if (path.empty())
+    return path;
+
+  FilePath::StringType path_str = path.StripTrailingSeparators().value();
+  if (!FilePath::IsSeparator(path_str[path_str.length() - 1]))
+    path_str.append(FILE_PATH_LITERAL("/"));
+
+  return FilePath(path_str).NormalizePathSeparators();
+}
+
+// Wrapper around ref-counted ExternalMountPoints that will be used to lazily
+// create and initialize LazyInstance system ExternalMountPoints.
+class SystemMountPointsLazyWrapper {
+ public:
+  SystemMountPointsLazyWrapper()
+      : system_mount_points_(fileapi::ExternalMountPoints::CreateRefCounted()) {
+    RegisterDefaultMountPoints();
+  }
+
+  ~SystemMountPointsLazyWrapper() {}
+
+  fileapi::ExternalMountPoints* get() {
+    return system_mount_points_.get();
+  }
+
+ private:
+  void RegisterDefaultMountPoints() {
+#if defined(OS_CHROMEOS)
+    // Add default system mount points.
+    system_mount_points_->RegisterFileSystem(
+        "archive",
+        fileapi::kFileSystemTypeNativeLocal,
+        FilePath(FILE_PATH_LITERAL("/media/archive")));
+    system_mount_points_->RegisterFileSystem(
+        "removable",
+        fileapi::kFileSystemTypeNativeLocal,
+        FilePath(FILE_PATH_LITERAL("/media/removable")));
+    system_mount_points_->RegisterFileSystem(
+        "oem",
+        fileapi::kFileSystemTypeRestrictedNativeLocal,
+        FilePath(FILE_PATH_LITERAL("/usr/share/oem")));
+
+    // TODO(tbarzic): Move this out of here.
+    FilePath home_path;
+    if (PathService::Get(base::DIR_HOME, &home_path)) {
+      system_mount_points_->RegisterFileSystem(
+          "Downloads",
+          fileapi::kFileSystemTypeNativeLocal,
+          home_path.AppendASCII("Downloads"));
+    }
+#endif  // defined(OS_CHROMEOS)
+  }
+
+  scoped_refptr<fileapi::ExternalMountPoints> system_mount_points_;
+};
+
+base::LazyInstance<SystemMountPointsLazyWrapper>::Leaky
+    g_external_mount_points = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace fileapi {
+
+class ExternalMountPoints::Instance {
+ public:
+  Instance(FileSystemType type,
+           const FilePath& path,
+           RemoteFileSystemProxyInterface* remote_proxy);
+
+  ~Instance();
+
+  FileSystemType type() const { return type_; }
+  const FilePath& path() const { return path_; }
+  RemoteFileSystemProxyInterface* remote_proxy() const {
+    return remote_proxy_.get();
+  }
+
+ private:
+  const FileSystemType type_;
+  const FilePath path_;
+
+  // For file systems that have a remote file system proxy.
+  scoped_refptr<RemoteFileSystemProxyInterface> remote_proxy_;
+
+  DISALLOW_COPY_AND_ASSIGN(Instance);
+};
+
+ExternalMountPoints::Instance::Instance(FileSystemType type,
+                                        const FilePath& path,
+                                        RemoteFileSystemProxyInterface* proxy)
+    : type_(type),
+      path_(path.StripTrailingSeparators()),
+      remote_proxy_(proxy) {
+  DCHECK(!proxy || (kFileSystemTypeDrive == type_));
+}
+
+ExternalMountPoints::Instance::~Instance() {}
+
+//--------------------------------------------------------------------------
+
+// static
+ExternalMountPoints* ExternalMountPoints::GetSystemInstance() {
+  return g_external_mount_points.Pointer()->get();
+}
+
+// static
+scoped_refptr<ExternalMountPoints> ExternalMountPoints::CreateRefCounted() {
+  return new ExternalMountPoints();
+}
+
+bool ExternalMountPoints::RegisterFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    const FilePath& path) {
+  return RegisterRemoteFileSystem(mount_name, type, NULL, path);
+}
+
+bool ExternalMountPoints::RegisterRemoteFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    RemoteFileSystemProxyInterface* remote_proxy,
+    const FilePath& path_in) {
+  base::AutoLock locker(lock_);
+
+  FilePath path = NormalizeFilePath(path_in);
+  if (!ValidateNewMountPoint(mount_name, path))
+    return false;
+
+  instance_map_[mount_name] = new Instance(type, path, remote_proxy);
+  if (!path.empty())
+    path_to_name_map_.insert(std::make_pair(path, mount_name));
+  return true;
+}
+
+bool ExternalMountPoints::RevokeFileSystem(const std::string& mount_name) {
+  base::AutoLock locker(lock_);
+  NameToInstance::iterator found = instance_map_.find(mount_name);
+  if (found == instance_map_.end())
+    return false;
+  Instance* instance = found->second;
+  path_to_name_map_.erase(NormalizeFilePath(instance->path()));
+  delete found->second;
+  instance_map_.erase(found);
+  return true;
+}
+
+bool ExternalMountPoints::GetRegisteredPath(
+    const std::string& filesystem_id, FilePath* path) const {
+  DCHECK(path);
+  base::AutoLock locker(lock_);
+  NameToInstance::const_iterator found = instance_map_.find(filesystem_id);
+  if (found == instance_map_.end())
+    return false;
+  *path = found->second->path();
+  return true;
+}
+
+bool ExternalMountPoints::CrackVirtualPath(const FilePath& virtual_path,
+                                           std::string* mount_name,
+                                           FileSystemType* type,
+                                           FilePath* path) const {
+  DCHECK(mount_name);
+  DCHECK(path);
+
+  // The path should not contain any '..' references.
+  if (virtual_path.ReferencesParent())
+    return false;
+
+  // The virtual_path should comprise of <mount_name> and <relative_path> parts.
+  std::vector<FilePath::StringType> components;
+  virtual_path.GetComponents(&components);
+  if (components.size() < 1)
+    return false;
+
+  std::vector<FilePath::StringType>::iterator component_iter =
+      components.begin();
+  std::string maybe_mount_name = FilePath(*component_iter++).MaybeAsASCII();
+  if (maybe_mount_name.empty())
+    return false;
+
+  FilePath cracked_path;
+  {
+    base::AutoLock locker(lock_);
+    NameToInstance::const_iterator found_instance =
+        instance_map_.find(maybe_mount_name);
+    if (found_instance == instance_map_.end())
+      return false;
+
+    *mount_name = maybe_mount_name;
+    const Instance* instance = found_instance->second;
+    if (type)
+      *type = instance->type();
+    cracked_path = instance->path();
+  }
+
+  for (; component_iter != components.end(); ++component_iter)
+    cracked_path = cracked_path.Append(*component_iter);
+  *path = cracked_path;
+  return true;
+}
+
+RemoteFileSystemProxyInterface* ExternalMountPoints::GetRemoteFileSystemProxy(
+    const std::string& mount_name) const {
+  base::AutoLock locker(lock_);
+  NameToInstance::const_iterator found = instance_map_.find(mount_name);
+  if (found == instance_map_.end())
+    return NULL;
+  return found->second->remote_proxy();
+}
+
+void ExternalMountPoints::AddMountPointInfosTo(
+    std::vector<MountPointInfo>* mount_points) const {
+  base::AutoLock locker(lock_);
+  DCHECK(mount_points);
+  for (NameToInstance::const_iterator iter = instance_map_.begin();
+       iter != instance_map_.end(); ++iter) {
+    mount_points->push_back(MountPointInfo(iter->first, iter->second->path()));
+  }
+}
+
+bool ExternalMountPoints::GetVirtualPath(const FilePath& path_in,
+                                         FilePath* virtual_path) {
+  DCHECK(virtual_path);
+
+  base::AutoLock locker(lock_);
+
+  FilePath path = NormalizeFilePath(path_in);
+  std::map<FilePath, std::string>::reverse_iterator iter(
+      path_to_name_map_.upper_bound(path));
+  if (iter == path_to_name_map_.rend())
+    return false;
+
+  *virtual_path = CreateVirtualRootPath(iter->second);
+  if (iter->first == path)
+    return true;
+  return iter->first.AppendRelativePath(path, virtual_path);
+}
+
+FilePath ExternalMountPoints::CreateVirtualRootPath(
+    const std::string& mount_name) const {
+  return FilePath().AppendASCII(mount_name);
+}
+
+ExternalMountPoints::ExternalMountPoints() {}
+
+ExternalMountPoints::~ExternalMountPoints() {
+  STLDeleteContainerPairSecondPointers(instance_map_.begin(),
+                                       instance_map_.end());
+}
+
+bool ExternalMountPoints::ValidateNewMountPoint(const std::string& mount_name,
+                                                const FilePath& path) {
+  lock_.AssertAcquired();
+
+  // Mount name must not be empty.
+  if (mount_name.empty())
+    return false;
+
+  // Verify there is no registered mount point with the same name.
+  NameToInstance::iterator found = instance_map_.find(mount_name);
+  if (found != instance_map_.end())
+    return false;
+
+  // Allow empty paths.
+  if (path.empty())
+    return true;
+
+  // Verify path is legal.
+  if (path.ReferencesParent() || !path.IsAbsolute())
+    return false;
+
+  // Check there the new path does not overlap with one of the existing ones.
+  std::map<FilePath, std::string>::reverse_iterator potential_parent(
+      path_to_name_map_.upper_bound(path));
+  if (potential_parent != path_to_name_map_.rend()) {
+    if (potential_parent->first == path ||
+        potential_parent->first.IsParent(path)) {
+      return false;
+    }
+  }
+
+  std::map<FilePath, std::string>::iterator potential_child =
+      path_to_name_map_.upper_bound(path);
+  if (potential_child == path_to_name_map_.end())
+    return true;
+  return !(potential_child->first == path) &&
+         !path.IsParent(potential_child->first);
+}
+
+ScopedExternalFileSystem::ScopedExternalFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    const FilePath& path)
+    : mount_name_(mount_name) {
+  ExternalMountPoints::GetSystemInstance()->RegisterFileSystem(
+      mount_name, type, path);
+}
+
+FilePath ScopedExternalFileSystem::GetVirtualRootPath() const {
+  return ExternalMountPoints::GetSystemInstance()->
+      CreateVirtualRootPath(mount_name_);
+}
+
+ScopedExternalFileSystem::~ScopedExternalFileSystem() {
+  ExternalMountPoints::GetSystemInstance()->RevokeFileSystem(mount_name_);
+}
+
+}  // namespace fileapi
+