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/storage_export.h"
  18 #include "webkit/common/fileapi/file_system_types.h"
  19
  20 class GURL;
  21
  22 namespace storage {
  23 class FileStreamReader;
  24 }
  25
  26 namespace storage {
  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 class WatcherManager;
  37
  38 // An interface for defining a file system backend.
  39 //
  40 // NOTE: when you implement a new FileSystemBackend for your own
  41 // FileSystem module, please contact to kinuko@chromium.org.
  42 //
  43 class STORAGE_EXPORT FileSystemBackend {
  44  public:
  45   // Callback for InitializeFileSystem.
  46   typedef base::Callback<void(const GURL& root_url,
  47                               const std::string& name,
  48                               base::File::Error error)>
  49       OpenFileSystemCallback;
  50   virtual ~FileSystemBackend() {}
  51
  52   // Returns true if this filesystem backend can handle |type|.
  53   // One filesystem backend may be able to handle multiple filesystem types.
  54   virtual bool CanHandleType(FileSystemType type) const = 0;
  55
  56   // This method is called right after the backend is registered in the
  57   // FileSystemContext and before any other methods are called. Each backend can
  58   // do additional initialization which depends on FileSystemContext here.
  59   virtual void Initialize(FileSystemContext* context) = 0;
  60
  61   // Resolves the filesystem root URL and the name for the given |url|.
  62   // This verifies if it is allowed to request (or create) the filesystem and if
  63   // it can access (or create) the root directory.
  64   // If |mode| is CREATE_IF_NONEXISTENT calling this may also create the root
  65   // directory (and/or related database entries etc) for the filesystem if it
  66   // doesn't exist.
  67   virtual void ResolveURL(const FileSystemURL& url,
  68                           OpenFileSystemMode mode,
  69                           const OpenFileSystemCallback& callback) = 0;
  70
  71   // Returns the specialized AsyncFileUtil for this backend.
  72   virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) = 0;
  73
  74   // Returns the specialized WatcherManager for this backend.
  75   virtual WatcherManager* GetWatcherManager(FileSystemType type) = 0;
  76
  77   // Returns the specialized CopyOrMoveFileValidatorFactory for this backend
  78   // and |type|.  If |error_code| is File::FILE_OK and the result is NULL,
  79   // then no validator is required.
  80   virtual CopyOrMoveFileValidatorFactory* GetCopyOrMoveFileValidatorFactory(
  81       FileSystemType type, base::File::Error* error_code) = 0;
  82
  83   // Returns a new instance of the specialized FileSystemOperation for this
  84   // backend based on the given triplet of |origin_url|, |file_system_type|
  85   // and |virtual_path|. On failure to create a file system operation, set
  86   // |error_code| correspondingly.
  87   // This method is usually dispatched by
  88   // FileSystemContext::CreateFileSystemOperation.
  89   virtual FileSystemOperation* CreateFileSystemOperation(
  90       const FileSystemURL& url,
  91       FileSystemContext* context,
  92       base::File::Error* error_code) const = 0;
  93
  94   // Returns true if Blobs accessing |url| should use FileStreamReader.
  95   // If false, Blobs are accessed using a snapshot file by calling
  96   // AsyncFileUtil::CreateSnapshotFile.
  97   virtual bool SupportsStreaming(const FileSystemURL& url) const = 0;
  98
  99   // Returns true if specified |type| of filesystem can handle Copy()
 100   // of the files in the same file system instead of streaming
 101   // read/write implementation.
 102   virtual bool HasInplaceCopyImplementation(FileSystemType type) const = 0;
 103
 104   // Creates a new file stream reader for a given filesystem URL |url| with an
 105   // offset |offset|. |expected_modification_time| specifies the expected last
 106   // modification if the value is non-null, the reader will check the underlying
 107   // file's actual modification time to see if the file has been modified, and
 108   // if it does any succeeding read operations should fail with
 109   // ERR_UPLOAD_FILE_CHANGED error.
 110   // This method itself does *not* check if the given path exists and is a
 111   // regular file.
 112   // The |length| argument says how many bytes are going to be read using the
 113   // instance of the file stream reader. If unknown, then equal to -1.
 114   virtual scoped_ptr<storage::FileStreamReader> CreateFileStreamReader(
 115       const FileSystemURL& url,
 116       int64 offset,
 117       const base::Time& expected_modification_time,
 118       FileSystemContext* context) const = 0;
 119
 120   // Creates a new file stream writer for a given filesystem URL |url| with an
 121   // offset |offset|.
 122   // This method itself does *not* check if the given path exists and is a
 123   // regular file.
 124   virtual scoped_ptr<FileStreamWriter> CreateFileStreamWriter(
 125       const FileSystemURL& url,
 126       int64 offset,
 127       FileSystemContext* context) const = 0;
 128
 129   // Returns the specialized FileSystemQuotaUtil for this backend.
 130   // This could return NULL if this backend does not support quota.
 131   virtual FileSystemQuotaUtil* GetQuotaUtil() = 0;
 132 };
 133
 134 // An interface to control external file system access permissions.
 135 // TODO(satorux): Move this out of 'webkit/browser/fileapi'. crbug.com/257279
 136 class ExternalFileSystemBackend : public FileSystemBackend {
 137  public:
 138   // Returns true if |url| is allowed to be accessed.
 139   // This is supposed to perform ExternalFileSystem-specific security
 140   // checks.
 141   virtual bool IsAccessAllowed(const storage::FileSystemURL& url) const = 0;
 142   // Returns the list of top level directories that are exposed by this
 143   // provider. This list is used to set appropriate child process file access
 144   // permissions.
 145   virtual std::vector<base::FilePath> GetRootDirectories() const = 0;
 146   // Grants access to all external file system from extension identified with
 147   // |extension_id|.
 148   virtual void GrantFullAccessToExtension(const std::string& extension_id) = 0;
 149   // Grants access to |virtual_path| from |origin_url|.
 150   virtual void GrantFileAccessToExtension(
 151       const std::string& extension_id,
 152       const base::FilePath& virtual_path) = 0;
 153   // Revokes file access from extension identified with |extension_id|.
 154   virtual void RevokeAccessForExtension(
 155         const std::string& extension_id) = 0;
 156   // Gets virtual path by known filesystem path. Returns false when filesystem
 157   // path is not exposed by this provider.
 158   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
 159                               base::FilePath* virtual_path) = 0;
 160 };
 161
 162 }  // namespace storage
 163
 164 #endif  // WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_