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      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_path.h"
     13 #include "base/memory/scoped_ptr.h"
     14 #include "base/platform_file.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 (at) 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::PlatformFileError 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   // Opens the filesystem for the given |origin_url| and |type|.
     61   // This verifies if it is allowed to request (or create) the filesystem
     62   // and if it can access (or create) the root directory.
     63   // If |mode| is CREATE_IF_NONEXISTENT calling this may also create
     64   // the root directory (and/or related database entries etc) for
     65   // the filesystem if it doesn't exist.
     66   virtual void OpenFileSystem(
     67       const GURL& origin_url,
     68       FileSystemType type,
     69       OpenFileSystemMode mode,
     70       const OpenFileSystemCallback& callback) = 0;
     71 
     72   // Returns the specialized FileSystemFileUtil for this backend.
     73   // It is ok to return NULL if the filesystem doesn't support synchronous
     74   // version of FileUtil.
     75   virtual FileSystemFileUtil* GetFileUtil(FileSystemType type) = 0;
     76 
     77   // Returns the specialized AsyncFileUtil for this backend.
     78   virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) = 0;
     79 
     80   // Returns the specialized CopyOrMoveFileValidatorFactory for this backend
     81   // and |type|.  If |error_code| is PLATFORM_FILE_OK and the result is NULL,
     82   // then no validator is required.
     83   virtual CopyOrMoveFileValidatorFactory* GetCopyOrMoveFileValidatorFactory(
     84       FileSystemType type, base::PlatformFileError* error_code) = 0;
     85 
     86   // Returns a new instance of the specialized FileSystemOperation for this
     87   // backend based on the given triplet of |origin_url|, |file_system_type|
     88   // and |virtual_path|. On failure to create a file system operation, set
     89   // |error_code| correspondingly.
     90   // This method is usually dispatched by
     91   // FileSystemContext::CreateFileSystemOperation.
     92   virtual FileSystemOperation* CreateFileSystemOperation(
     93       const FileSystemURL& url,
     94       FileSystemContext* context,
     95       base::PlatformFileError* error_code) const = 0;
     96 
     97   // Creates a new file stream reader for a given filesystem URL |url| with an
     98   // offset |offset|. |expected_modification_time| specifies the expected last
     99   // modification if the value is non-null, the reader will check the underlying
    100   // file's actual modification time to see if the file has been modified, and
    101   // if it does any succeeding read operations should fail with
    102   // ERR_UPLOAD_FILE_CHANGED error.
    103   // This method itself does *not* check if the given path exists and is a
    104   // regular file.
    105   virtual scoped_ptr<webkit_blob::FileStreamReader> CreateFileStreamReader(
    106     const FileSystemURL& url,
    107     int64 offset,
    108     const base::Time& expected_modification_time,
    109     FileSystemContext* context) const = 0;
    110 
    111   // Creates a new file stream writer for a given filesystem URL |url| with an
    112   // offset |offset|.
    113   // This method itself does *not* check if the given path exists and is a
    114   // regular file.
    115   virtual scoped_ptr<FileStreamWriter> CreateFileStreamWriter(
    116       const FileSystemURL& url,
    117       int64 offset,
    118       FileSystemContext* context) const = 0;
    119 
    120   // Returns the specialized FileSystemQuotaUtil for this backend.
    121   // This could return NULL if this backend does not support quota.
    122   virtual FileSystemQuotaUtil* GetQuotaUtil() = 0;
    123 };
    124 
    125 // An interface to control external file system access permissions.
    126 // TODO(satorux): Move this out of 'webkit/browser/fileapi'. crbug.com/257279
    127 class ExternalFileSystemBackend : public FileSystemBackend {
    128  public:
    129   // Returns true if |url| is allowed to be accessed.
    130   // This is supposed to perform ExternalFileSystem-specific security
    131   // checks.
    132   virtual bool IsAccessAllowed(const fileapi::FileSystemURL& url) const = 0;
    133   // Returns the list of top level directories that are exposed by this
    134   // provider. This list is used to set appropriate child process file access
    135   // permissions.
    136   virtual std::vector<base::FilePath> GetRootDirectories() const = 0;
    137   // Grants access to all external file system from extension identified with
    138   // |extension_id|.
    139   virtual void GrantFullAccessToExtension(const std::string& extension_id) = 0;
    140   // Grants access to |virtual_path| from |origin_url|.
    141   virtual void GrantFileAccessToExtension(
    142       const std::string& extension_id,
    143       const base::FilePath& virtual_path) = 0;
    144   // Revokes file access from extension identified with |extension_id|.
    145   virtual void RevokeAccessForExtension(
    146         const std::string& extension_id) = 0;
    147   // Gets virtual path by known filesystem path. Returns false when filesystem
    148   // path is not exposed by this provider.
    149   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
    150                               base::FilePath* virtual_path) = 0;
    151 };
    152 
    153 }  // namespace fileapi
    154 
    155 #endif  // WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
    156