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
20class GURL;
21
22namespace webkit_blob {
23class FileStreamReader;
24}
25
26namespace fileapi {
27
28class AsyncFileUtil;
29class CopyOrMoveFileValidatorFactory;
30class FileSystemURL;
31class FileStreamWriter;
32class FileSystemContext;
33class FileSystemFileUtil;
34class FileSystemOperation;
35class 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//
42class 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
125class 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_
154