webkit/browser/fileapi/file_system_backend.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
   6 #define WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/callback_forward.h"
  12 #include "base/files/file.h"
  13 #include "base/files/file_path.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "webkit/browser/fileapi/file_permission_policy.h"
  16 #include "webkit/browser/fileapi/open_file_system_mode.h"
  17 #include "webkit/browser/webkit_storage_browser_export.h"
  18 #include "webkit/common/fileapi/file_system_types.h"
  19
  20 class GURL;
  21
  22 namespace webkit_blob {
  23 class FileStreamReader;
  24 }
  25
  26 namespace fileapi {
  27
  28 class AsyncFileUtil;
  29 class CopyOrMoveFileValidatorFactory;
  30 class FileSystemURL;
  31 class FileStreamWriter;
  32 class FileSystemContext;
  33 class FileSystemFileUtil;
  34 class FileSystemOperation;
  35 class FileSystemQuotaUtil;
  36
  37 // An interface for defining a file system backend.
  38 //
  39 // NOTE: when you implement a new FileSystemBackend for your own
  40 // FileSystem module, please contact to kinuko@chromium.org.
  41 //
  42 class WEBKIT_STORAGE_BROWSER_EXPORT FileSystemBackend {
  43  public:
  44   // Callback for InitializeFileSystem.
  45   typedef base::Callback<void(const GURL& root_url,
  46                               const std::string& name,
  47                               base::File::Error error)>
  48       OpenFileSystemCallback;
  49   virtual ~FileSystemBackend() {}
  50
  51   // Returns true if this filesystem backend can handle |type|.
  52   // One filesystem backend may be able to handle multiple filesystem types.
  53   virtual bool CanHandleType(FileSystemType type) const = 0;
  54
  55   // This method is called right after the backend is registered in the
  56   // FileSystemContext and before any other methods are called. Each backend can
  57   // do additional initialization which depends on FileSystemContext here.
  58   virtual void Initialize(FileSystemContext* context) = 0;
  59
  60   // Resolves the filesystem root URL and the name for the given |url|.
  61   // This verifies if it is allowed to request (or create) the filesystem and if
  62   // it can access (or create) the root directory.
  63   // If |mode| is CREATE_IF_NONEXISTENT calling this may also create the root
  64   // directory (and/or related database entries etc) for the filesystem if it
  65   // doesn't exist.
  66   virtual void ResolveURL(const FileSystemURL& url,
  67                           OpenFileSystemMode mode,
  68                           const OpenFileSystemCallback& callback) = 0;
  69
  70   // Returns the specialized AsyncFileUtil for this backend.
  71   virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) = 0;
  72
  73   // Returns the specialized CopyOrMoveFileValidatorFactory for this backend
  74   // and |type|.  If |error_code| is File::FILE_OK and the result is NULL,
  75   // then no validator is required.
  76   virtual CopyOrMoveFileValidatorFactory* GetCopyOrMoveFileValidatorFactory(
  77       FileSystemType type, base::File::Error* error_code) = 0;
  78
  79   // Returns a new instance of the specialized FileSystemOperation for this
  80   // backend based on the given triplet of |origin_url|, |file_system_type|
  81   // and |virtual_path|. On failure to create a file system operation, set
  82   // |error_code| correspondingly.
  83   // This method is usually dispatched by
  84   // FileSystemContext::CreateFileSystemOperation.
  85   virtual FileSystemOperation* CreateFileSystemOperation(
  86       const FileSystemURL& url,
  87       FileSystemContext* context,
  88       base::File::Error* error_code) const = 0;
  89
  90   // Returns true if Blobs accessing |url| should use FileStreamReader.
  91   // If false, Blobs are accessed using a snapshot file by calling
  92   // AsyncFileUtil::CreateSnapshotFile.
  93   virtual bool SupportsStreaming(const FileSystemURL& url) const = 0;
  94
  95   // Creates a new file stream reader for a given filesystem URL |url| with an
  96   // offset |offset|. |expected_modification_time| specifies the expected last
  97   // modification if the value is non-null, the reader will check the underlying
  98   // file's actual modification time to see if the file has been modified, and
  99   // if it does any succeeding read operations should fail with
 100   // ERR_UPLOAD_FILE_CHANGED error.
 101   // This method itself does *not* check if the given path exists and is a
 102   // regular file.
 103   virtual scoped_ptr<webkit_blob::FileStreamReader> CreateFileStreamReader(
 104       const FileSystemURL& url,
 105       int64 offset,
 106       const base::Time& expected_modification_time,
 107       FileSystemContext* context) const = 0;
 108
 109   // Creates a new file stream writer for a given filesystem URL |url| with an
 110   // offset |offset|.
 111   // This method itself does *not* check if the given path exists and is a
 112   // regular file.
 113   virtual scoped_ptr<FileStreamWriter> CreateFileStreamWriter(
 114       const FileSystemURL& url,
 115       int64 offset,
 116       FileSystemContext* context) const = 0;
 117
 118   // Returns the specialized FileSystemQuotaUtil for this backend.
 119   // This could return NULL if this backend does not support quota.
 120   virtual FileSystemQuotaUtil* GetQuotaUtil() = 0;
 121 };
 122
 123 // An interface to control external file system access permissions.
 124 // TODO(satorux): Move this out of 'webkit/browser/fileapi'. crbug.com/257279
 125 class ExternalFileSystemBackend : public FileSystemBackend {
 126  public:
 127   // Returns true if |url| is allowed to be accessed.
 128   // This is supposed to perform ExternalFileSystem-specific security
 129   // checks.
 130   virtual bool IsAccessAllowed(const fileapi::FileSystemURL& url) const = 0;
 131   // Returns the list of top level directories that are exposed by this
 132   // provider. This list is used to set appropriate child process file access
 133   // permissions.
 134   virtual std::vector<base::FilePath> GetRootDirectories() const = 0;
 135   // Grants access to all external file system from extension identified with
 136   // |extension_id|.
 137   virtual void GrantFullAccessToExtension(const std::string& extension_id) = 0;
 138   // Grants access to |virtual_path| from |origin_url|.
 139   virtual void GrantFileAccessToExtension(
 140       const std::string& extension_id,
 141       const base::FilePath& virtual_path) = 0;
 142   // Revokes file access from extension identified with |extension_id|.
 143   virtual void RevokeAccessForExtension(
 144         const std::string& extension_id) = 0;
 145   // Gets virtual path by known filesystem path. Returns false when filesystem
 146   // path is not exposed by this provider.
 147   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
 148                               base::FilePath* virtual_path) = 0;
 149 };
 150
 151 }  // namespace fileapi
 152
 153 #endif  // WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_