Home | History | Annotate | Download | only in fileapi 
      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 STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
      6 #define STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
      7 
      8 #include <limits>
      9 #include <string>
     10 #include <vector>
     11 
     12 #include "base/callback_forward.h"
     13 #include "base/files/file.h"
     14 #include "base/files/file_path.h"
     15 #include "base/memory/scoped_ptr.h"
     16 #include "storage/browser/fileapi/file_permission_policy.h"
     17 #include "storage/browser/fileapi/open_file_system_mode.h"
     18 #include "storage/browser/fileapi/task_runner_bound_observer_list.h"
     19 #include "storage/browser/storage_browser_export.h"
     20 #include "storage/common/fileapi/file_system_types.h"
     21 
     22 class GURL;
     23 
     24 namespace storage {
     25 
     26 class AsyncFileUtil;
     27 class CopyOrMoveFileValidatorFactory;
     28 class FileSystemURL;
     29 class FileStreamReader;
     30 class FileStreamWriter;
     31 class FileSystemContext;
     32 class FileSystemFileUtil;
     33 class FileSystemOperation;
     34 class FileSystemQuotaUtil;
     35 class WatcherManager;
     36 
     37 // Callback to take GURL.
     38 typedef base::Callback<void(const GURL& url)> URLCallback;
     39 
     40 // Maximum numer of bytes to be read by FileStreamReader classes. Used in
     41 // FileSystemBackend::CreateFileStreamReader(), when it's not known how many
     42 // bytes will be fetched in total.
     43 const int64 kMaximumLength = std::numeric_limits<int64>::max();
     44 
     45 // An interface for defining a file system backend.
     46 //
     47 // NOTE: when you implement a new FileSystemBackend for your own
     48 // FileSystem module, please contact to kinuko (at) chromium.org.
     49 //
     50 class STORAGE_EXPORT FileSystemBackend {
     51  public:
     52   // Callback for InitializeFileSystem.
     53   typedef base::Callback<void(const GURL& root_url,
     54                               const std::string& name,
     55                               base::File::Error error)>
     56       OpenFileSystemCallback;
     57   virtual ~FileSystemBackend() {}
     58 
     59   // Returns true if this filesystem backend can handle |type|.
     60   // One filesystem backend may be able to handle multiple filesystem types.
     61   virtual bool CanHandleType(FileSystemType type) const = 0;
     62 
     63   // This method is called right after the backend is registered in the
     64   // FileSystemContext and before any other methods are called. Each backend can
     65   // do additional initialization which depends on FileSystemContext here.
     66   virtual void Initialize(FileSystemContext* context) = 0;
     67 
     68   // Resolves the filesystem root URL and the name for the given |url|.
     69   // This verifies if it is allowed to request (or create) the filesystem and if
     70   // it can access (or create) the root directory.
     71   // If |mode| is CREATE_IF_NONEXISTENT calling this may also create the root
     72   // directory (and/or related database entries etc) for the filesystem if it
     73   // doesn't exist.
     74   virtual void ResolveURL(const FileSystemURL& url,
     75                           OpenFileSystemMode mode,
     76                           const OpenFileSystemCallback& callback) = 0;
     77 
     78   // Returns the specialized AsyncFileUtil for this backend.
     79   virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) = 0;
     80 
     81   // Returns the specialized WatcherManager for this backend.
     82   virtual WatcherManager* GetWatcherManager(FileSystemType type) = 0;
     83 
     84   // Returns the specialized CopyOrMoveFileValidatorFactory for this backend
     85   // and |type|.  If |error_code| is File::FILE_OK and the result is NULL,
     86   // then no validator is required.
     87   virtual CopyOrMoveFileValidatorFactory* GetCopyOrMoveFileValidatorFactory(
     88       FileSystemType type, base::File::Error* error_code) = 0;
     89 
     90   // Returns a new instance of the specialized FileSystemOperation for this
     91   // backend based on the given triplet of |origin_url|, |file_system_type|
     92   // and |virtual_path|. On failure to create a file system operation, set
     93   // |error_code| correspondingly.
     94   // This method is usually dispatched by
     95   // FileSystemContext::CreateFileSystemOperation.
     96   virtual FileSystemOperation* CreateFileSystemOperation(
     97       const FileSystemURL& url,
     98       FileSystemContext* context,
     99       base::File::Error* error_code) const = 0;
    100 
    101   // Returns true if Blobs accessing |url| should use FileStreamReader.
    102   // If false, Blobs are accessed using a snapshot file by calling
    103   // AsyncFileUtil::CreateSnapshotFile.
    104   virtual bool SupportsStreaming(const FileSystemURL& url) const = 0;
    105 
    106   // Returns true if specified |type| of filesystem can handle Copy()
    107   // of the files in the same file system instead of streaming
    108   // read/write implementation.
    109   virtual bool HasInplaceCopyImplementation(FileSystemType type) const = 0;
    110 
    111   // Creates a new file stream reader for a given filesystem URL |url| with an
    112   // offset |offset|. |expected_modification_time| specifies the expected last
    113   // modification if the value is non-null, the reader will check the underlying
    114   // file's actual modification time to see if the file has been modified, and
    115   // if it does any succeeding read operations should fail with
    116   // ERR_UPLOAD_FILE_CHANGED error.
    117   // This method itself does *not* check if the given path exists and is a
    118   // regular file. At most |max_bytes_to_read| can be fetched from the file
    119   // stream reader.
    120   virtual scoped_ptr<storage::FileStreamReader> CreateFileStreamReader(
    121       const FileSystemURL& url,
    122       int64 offset,
    123       int64 max_bytes_to_read,
    124       const base::Time& expected_modification_time,
    125       FileSystemContext* context) const = 0;
    126 
    127   // Creates a new file stream writer for a given filesystem URL |url| with an
    128   // offset |offset|.
    129   // This method itself does *not* check if the given path exists and is a
    130   // regular file.
    131   virtual scoped_ptr<FileStreamWriter> CreateFileStreamWriter(
    132       const FileSystemURL& url,
    133       int64 offset,
    134       FileSystemContext* context) const = 0;
    135 
    136   // Returns the specialized FileSystemQuotaUtil for this backend.
    137   // This could return NULL if this backend does not support quota.
    138   virtual FileSystemQuotaUtil* GetQuotaUtil() = 0;
    139 
    140   // Returns the update observer list for |type|. It may return NULL when no
    141   // observers are added.
    142   virtual const UpdateObserverList* GetUpdateObservers(
    143       FileSystemType type) const = 0;
    144 
    145   // Returns the change observer list for |type|. It may return NULL when no
    146   // observers are added.
    147   virtual const ChangeObserverList* GetChangeObservers(
    148       FileSystemType type) const = 0;
    149 
    150   // Returns the access observer list for |type|. It may return NULL when no
    151   // observers are added.
    152   virtual const AccessObserverList* GetAccessObservers(
    153       FileSystemType type) const = 0;
    154 };
    155 
    156 // An interface to control external file system access permissions.
    157 // TODO(satorux): Move this out of 'storage/browser/fileapi'. crbug.com/257279
    158 class ExternalFileSystemBackend : public FileSystemBackend {
    159  public:
    160   // Returns true if |url| is allowed to be accessed.
    161   // This is supposed to perform ExternalFileSystem-specific security
    162   // checks.
    163   virtual bool IsAccessAllowed(const storage::FileSystemURL& url) const = 0;
    164   // Returns the list of top level directories that are exposed by this
    165   // provider. This list is used to set appropriate child process file access
    166   // permissions.
    167   virtual std::vector<base::FilePath> GetRootDirectories() const = 0;
    168   // Grants access to all external file system from extension identified with
    169   // |extension_id|.
    170   virtual void GrantFullAccessToExtension(const std::string& extension_id) = 0;
    171   // Grants access to |virtual_path| from |origin_url|.
    172   virtual void GrantFileAccessToExtension(
    173       const std::string& extension_id,
    174       const base::FilePath& virtual_path) = 0;
    175   // Revokes file access from extension identified with |extension_id|.
    176   virtual void RevokeAccessForExtension(
    177         const std::string& extension_id) = 0;
    178   // Gets virtual path by known filesystem path. Returns false when filesystem
    179   // path is not exposed by this provider.
    180   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
    181                               base::FilePath* virtual_path) = 0;
    182   // Gets a redirect URL for contents. e.g. Google Drive URL for hosted
    183   // documents. Returns empty URL if the entry does not have the redirect URL.
    184   virtual void GetRedirectURLForContents(
    185       const storage::FileSystemURL& url,
    186       const storage::URLCallback& callback) = 0;
    187 };
    188 
    189 }  // namespace storage
    190 
    191 #endif  // STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
    192