text: // Copyright 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.
  
  #ifndef CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_H_
  #define CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_H_
  
  #include <string>
  #include <vector>
  
  #include "base/compiler_specific.h"
  #include "base/files/file_path.h"
  #include "base/memory/scoped_ptr.h"
  #include "webkit/browser/fileapi/file_system_backend.h"
  #include "webkit/browser/quota/special_storage_policy.h"
  #include "webkit/common/fileapi/file_system_types.h"
  
  namespace storage {
  class CopyOrMoveFileValidatorFactory;
  class ExternalMountPoints;
  class FileSystemURL;
  }  // namespace storage
  
  namespace chromeos {
  
  class FileSystemBackendDelegate;
  class FileAccessPermissions;
  
  // FileSystemBackend is a Chrome OS specific implementation of
  // ExternalFileSystemBackend. This class is responsible for a
  // number of things, including:
  //
  // - Add system mount points
  // - Grant/revoke/check file access permissions
  // - Create FileSystemOperation per file system type
  // - Create FileStreamReader/Writer per file system type
  //
  // Chrome OS specific mount points:
  //
  // "Downloads" is a mount point for user's Downloads directory on the local
  // disk, where downloaded files are stored by default.
  //
  // "archive" is a mount point for an archive file, such as a zip file. This
  // mount point exposes contents of an archive file via cros_disks and AVFS
  // <http://avf.sourceforge.net/>.
  //
  // "removable" is a mount point for removable media such as an SD card.
  // Insertion and removal of removable media are handled by cros_disks.
  //
  // "oem" is a read-only mount point for a directory containing OEM data.
  //
  // "drive" is a mount point for Google Drive. Drive is integrated with the
  // FileSystem API layer via drive::FileSystemProxy. This mount point is added
  // by drive::DriveIntegrationService.
  //
  // These mount points are placed under the "external" namespace, and file
  // system URLs for these mount points look like:
  //
  //   filesystem:<origin>/external/<mount_name>/...
  //
  class FileSystemBackend : public storage::ExternalFileSystemBackend {
   public:
    using storage::FileSystemBackend::OpenFileSystemCallback;
  
    // FileSystemBackend will take an ownership of a |mount_points|
    // reference. On the other hand, |system_mount_points| will be kept as a raw
    // pointer and it should outlive FileSystemBackend instance.
    // The ownerships of |drive_delegate| and |file_system_provider_delegate| are
    // also taken.
    FileSystemBackend(
        FileSystemBackendDelegate* drive_delegate,
        FileSystemBackendDelegate* file_system_provider_delegate,
        FileSystemBackendDelegate* mtp_delegate,
        scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy,
        scoped_refptr<storage::ExternalMountPoints> mount_points,
        storage::ExternalMountPoints* system_mount_points);
    virtual ~FileSystemBackend();
  
    // Adds system mount points, such as "archive", and "removable". This
    // function is no-op if these mount points are already present.
    void AddSystemMountPoints();
  
    // Returns true if CrosMountpointProvider can handle |url|, i.e. its
    // file system type matches with what this provider supports.
    // This could be called on any threads.
    static bool CanHandleURL(const storage::FileSystemURL& url);
  
    // storage::FileSystemBackend overrides.
    virtual bool CanHandleType(storage::FileSystemType type) const OVERRIDE;
    virtual void Initialize(storage::FileSystemContext* context) OVERRIDE;
    virtual void ResolveURL(const storage::FileSystemURL& url,
                            storage::OpenFileSystemMode mode,
                            const OpenFileSystemCallback& callback) OVERRIDE;
    virtual storage::AsyncFileUtil* GetAsyncFileUtil(
        storage::FileSystemType type) OVERRIDE;
    virtual storage::CopyOrMoveFileValidatorFactory*
        GetCopyOrMoveFileValidatorFactory(storage::FileSystemType type,
                                          base::File::Error* error_code) OVERRIDE;
    virtual storage::FileSystemOperation* CreateFileSystemOperation(
        const storage::FileSystemURL& url,
        storage::FileSystemContext* context,
        base::File::Error* error_code) const OVERRIDE;
    virtual bool SupportsStreaming(
        const storage::FileSystemURL& url) const OVERRIDE;
    virtual bool HasInplaceCopyImplementation(
        storage::FileSystemType type) const OVERRIDE;
    virtual scoped_ptr<storage::FileStreamReader> CreateFileStreamReader(
        const storage::FileSystemURL& path,
        int64 offset,
        const base::Time& expected_modification_time,
        storage::FileSystemContext* context) const OVERRIDE;
    virtual scoped_ptr<storage::FileStreamWriter> CreateFileStreamWriter(
        const storage::FileSystemURL& url,
        int64 offset,
        storage::FileSystemContext* context) const OVERRIDE;
    virtual storage::FileSystemQuotaUtil* GetQuotaUtil() OVERRIDE;
  
    // storage::ExternalFileSystemBackend overrides.
    virtual bool IsAccessAllowed(
        const storage::FileSystemURL& url) const OVERRIDE;
    virtual std::vector<base::FilePath> GetRootDirectories() const OVERRIDE;
    virtual void GrantFullAccessToExtension(
        const std::string& extension_id) OVERRIDE;
    virtual void GrantFileAccessToExtension(
        const std::string& extension_id,
        const base::FilePath& virtual_path) OVERRIDE;
    virtual void RevokeAccessForExtension(
        const std::string& extension_id) OVERRIDE;
    virtual bool GetVirtualPath(const base::FilePath& filesystem_path,
                                base::FilePath* virtual_path) OVERRIDE;
  
   private:
    scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy_;
    scoped_ptr<FileAccessPermissions> file_access_permissions_;
    scoped_ptr<storage::AsyncFileUtil> local_file_util_;
  
    // The delegate instance for the drive file system related operations.
    scoped_ptr<FileSystemBackendDelegate> drive_delegate_;
  
    // The delegate instance for the provided file system related operations.
    scoped_ptr<FileSystemBackendDelegate> file_system_provider_delegate_;
  
    // The delegate instance for the MTP file system related operations.
    scoped_ptr<FileSystemBackendDelegate> mtp_delegate_;
  
    // Mount points specific to the owning context (i.e. per-profile mount
    // points).
    //
    // It is legal to have mount points with the same name as in
    // system_mount_points_. Also, mount point paths may overlap with mount point
    // paths in system_mount_points_. In both cases mount points in
    // |mount_points_| will have a priority.
    // E.g. if |mount_points_| map 'foo1' to '/foo/foo1' and
    // |file_system_mount_points_| map 'xxx' to '/foo/foo1/xxx', |GetVirtualPaths|
    // will resolve '/foo/foo1/xxx/yyy' as 'foo1/xxx/yyy' (i.e. the mapping from
    // |mount_points_| will be used).
    scoped_refptr<storage::ExternalMountPoints> mount_points_;
  
    // Globally visible mount points. System MountPonts instance should outlive
    // all FileSystemBackend instances, so raw pointer is safe.
    storage::ExternalMountPoints* system_mount_points_;
  
    DISALLOW_COPY_AND_ASSIGN(FileSystemBackend);
  };
  
  }  // namespace chromeos
  
  #endif  // CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_H_
  