Cleanup: return value and null-callback fixups on AsyncFileUtil interface

webkit/browser/fileapi/async_file_util.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WEBKIT_BROWSER_FILEAPI_ASYNC_FILE_UTIL_H_
 #define WEBKIT_BROWSER_FILEAPI_ASYNC_FILE_UTIL_H_
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/files/file_util_proxy.h"
@@ skipping 20 matching lines @@
 //
 // Each filesystem which needs to be dispatched from LocalFileSystemOperation
 // must implement this interface or a synchronous version of interface:
 // FileSystemFileUtil.
 //
 // As far as an instance of this class is owned by a MountPointProvider
 // (which is owned by FileSystemContext), it's guaranteed that this instance's
 // alive while FileSystemOperationContext given to each operation is kept
 // alive. (Note that this instance might be freed on different thread
 // from the thread it is created.)
+//
+// It is NOT valid to give null callback to this class, and implementors
+// can assume that they don't get any null callbacks.
+//
 class WEBKIT_STORAGE_BROWSER_EXPORT AsyncFileUtil {
  public:
   typedef base::Callback<
       void(base::PlatformFileError result)> StatusCallback;
 
   typedef base::Callback<
       void(base::PlatformFileError result,
            base::PassPlatformFile file)> CreateOrOpenCallback;
 
   typedef base::Callback<
@@ skipping 21 matching lines @@
   virtual ~AsyncFileUtil() {}
 
   // Creates or opens a file with the given flags.
   // If PLATFORM_FILE_CREATE is set in |file_flags| it always tries to create
   // a new file at the given |url| and calls back with
   // PLATFORM_FILE_ERROR_FILE_EXISTS if the |url| already exists.
   //
   // LocalFileSystemOperation::OpenFile calls this.
   // This is used only by Pepper/NaCL File API.
   //
-  // This returns false if it fails to post an async task.
-  //
-  virtual bool CreateOrOpen(
+  virtual void CreateOrOpen(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       int file_flags,
       const CreateOrOpenCallback& callback) = 0;
 
   // Ensures that the given |url| exist.  This creates a empty new file
   // at |url| if the |url| does not exist.
   //
   // LocalFileSystemOperation::CreateFile calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_OK and created==true if a file has not existed and
   //   is created at |url|.
   // - PLATFORM_FILE_OK and created==false if the file already exists.
   // - Other error code (with created=false) if a file hasn't existed yet
   //   and there was an error while creating a new file.
   //
-  virtual bool EnsureFileExists(
+  virtual void EnsureFileExists(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const EnsureFileExistsCallback& callback) = 0;
 
   // Creates directory at given url.
   //
   // LocalFileSystemOperation::CreateDirectory calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if the |url|'s parent directory
   //   does not exist and |recursive| is false.
   // - PLATFORM_FILE_ERROR_EXISTS if a directory already exists at |url|
   //   and |exclusive| is true.
   // - PLATFORM_FILE_ERROR_EXISTS if a file already exists at |url|
   //   (regardless of |exclusive| value).
   // - Other error code if it failed to create a directory.
   //
-  virtual bool CreateDirectory(
+  virtual void CreateDirectory(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       bool exclusive,
       bool recursive,
       const StatusCallback& callback) = 0;
 
   // Retrieves the information about a file.
   //
   // LocalFileSystemOperation::GetMetadata calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if the file doesn't exist.
   // - Other error code if there was an error while retrieving the file info.
   //
-  virtual bool GetFileInfo(
+  virtual void GetFileInfo(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const GetFileInfoCallback& callback) = 0;
 
   // Reads contents of a directory at |path|.
   //
   // LocalFileSystemOperation::ReadDirectory calls this.
   //
   // Note that the |name| field of each entry in |file_list|
   // returned by |callback| should have a base file name
   // of the entry relative to the directory, but not an absolute path.
   //
   // (E.g. if ReadDirectory is called for a directory
   // 'path/to/dir' and the directory has entries 'a' and 'b',
   // the returned |file_list| should include entries whose names
   // are 'a' and 'b', but not '/path/to/dir/a' and '/path/to/dir/b'.)
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if the target directory doesn't exist.
   // - PLATFORM_FILE_ERROR_NOT_A_DIRECTORY if an entry exists at |url| but
   //   is a file (not a directory).
   //
-  virtual bool ReadDirectory(
+  virtual void ReadDirectory(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const ReadDirectoryCallback& callback) = 0;
 
   // Modifies timestamps of a file or directory at |url| with
   // |last_access_time| and |last_modified_time|. The function DOES NOT
   // create a file unlike 'touch' command on Linux.
   //
   // LocalFileSystemOperation::TouchFile calls this.
   // This is used only by Pepper/NaCL File API.
   //
-  // This returns false if it fails to post an async task.
-  virtual bool Touch(
+  virtual void Touch(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const base::Time& last_access_time,
       const base::Time& last_modified_time,
       const StatusCallback& callback) = 0;
 
   // Truncates a file at |path| to |length|. If |length| is larger than
   // the original file size, the file will be extended, and the extended
   // part is filled with null bytes.
   //
   // LocalFileSystemOperation::Truncate calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if the file doesn't exist.
   //
-  virtual bool Truncate(
+  virtual void Truncate(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       int64 length,
       const StatusCallback& callback) = 0;
 
   // Copies a file from |src_url| to |dest_url|.
   // This must be called for files that belong to the same filesystem
   // (i.e. type() and origin() of the |src_url| and |dest_url| must match).
   //
   // LocalFileSystemOperation::Copy calls this for same-filesystem copy case.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_url|
   //   or the parent directory of |dest_url| does not exist.
   // - PLATFORM_FILE_ERROR_NOT_A_FILE if |src_url| exists but is not a file.
   // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
   //   is not a file.
   // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
   //   its parent path is a file.
   //
-  virtual bool CopyFileLocal(
+  virtual void CopyFileLocal(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& src_url,
       const FileSystemURL& dest_url,
       const StatusCallback& callback) = 0;
 
   // Moves a local file from |src_url| to |dest_url|.
   // This must be called for files that belong to the same filesystem
   // (i.e. type() and origin() of the |src_url| and |dest_url| must match).
   //
   // LocalFileSystemOperation::Move calls this for same-filesystem move case.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_url|
   //   or the parent directory of |dest_url| does not exist.
   // - PLATFORM_FILE_ERROR_NOT_A_FILE if |src_url| exists but is not a file.
   // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
   //   is not a file.
   // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
   //   its parent path is a file.
   //
-  virtual bool MoveFileLocal(
+  virtual void MoveFileLocal(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& src_url,
       const FileSystemURL& dest_url,
       const StatusCallback& callback) = 0;
 
   // Copies in a single file from a different filesystem.
   //
   // LocalFileSystemOperation::Copy or Move calls this for cross-filesystem
   // cases.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_file_path|
   //   or the parent directory of |dest_url| does not exist.
   // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
   //   is not a file.
   // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
   //   its parent path is a file.
   //
-  virtual bool CopyInForeignFile(
+  virtual void CopyInForeignFile(
         scoped_ptr<FileSystemOperationContext> context,
         const base::FilePath& src_file_path,
         const FileSystemURL& dest_url,
         const StatusCallback& callback) = 0;
 
   // Deletes a single file.
   //
   // LocalFileSystemOperation::RemoveFile calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
   // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| is not a file.
   //
-  virtual bool DeleteFile(
+  virtual void DeleteFile(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const StatusCallback& callback) = 0;
 
   // Removes a single empty directory.
   //
   // LocalFileSystemOperation::RemoveDirectory calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
   // - PLATFORM_FILE_ERROR_NOT_A_DIRECTORY if |url| is not a directory.
   // - PLATFORM_FILE_ERROR_NOT_EMPTY if |url| is not empty.
   //
-  virtual bool DeleteDirectory(
+  virtual void DeleteDirectory(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const StatusCallback& callback) = 0;
 
   // Removes a single file or a single directory with its contents
   // (i.e. files/subdirectories under the directory).
   //
   // LocalFileSystemOperation::Remove calls this.
   // On some platforms, such as Chrome OS Drive File System, recursive file
   // deletion can be implemented more efficiently than calling DeleteFile() and
   // DeleteDirectory() for each files/directories.
   // This method is optional, so if not supported,
   // PLATFORM_ERROR_INVALID_OPERATION should be returned via |callback|.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
   // - PLATFORM_ERROR_INVALID_OPERATION if this operation is not supported.
-  virtual bool DeleteRecursively(
+  virtual void DeleteRecursively(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const StatusCallback& callback) = 0;
 
   // Creates a local snapshot file for a given |url| and returns the
   // metadata and platform path of the snapshot file via |callback|.
   // In regular filesystem cases the implementation may simply return
   // the metadata of the file itself (as well as GetMetadata does),
   // while in non-regular filesystem case the backend may create a
   // temporary snapshot file which holds the file data and return
   // the metadata of the temporary file.
   //
   // In the callback, it returns:
   // |file_info| is the metadata of the snapshot file created.
   // |platform_path| is the full absolute platform path to the snapshot
   // file created.  If a file is not backed by a real local file in
   // the implementor's FileSystem, the implementor must create a
   // local snapshot file and return the path of the created file.
   //
   // If implementors creates a temporary file for snapshotting and wants
   // FileAPI backend to take care of the lifetime of the file (so that
   // it won't get deleted while JS layer has any references to the created
   // File/Blob object), it should return non-empty |file_ref|.
   // Via the |file_ref| implementors can schedule a file deletion
   // or arbitrary callbacks when the last reference of File/Blob is dropped.
   //
   // LocalFileSystemOperation::CreateSnapshotFile calls this.
   //
-  // This returns false if it fails to post an async task.
-  //
   // This reports following error code via |callback|:
   // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
   // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| exists but is a directory.
   //
   // The field values of |file_info| are undefined (implementation
   // dependent) in error cases, and the caller should always
   // check the return code.
-  virtual bool CreateSnapshotFile(
+  virtual void CreateSnapshotFile(
       scoped_ptr<FileSystemOperationContext> context,
       const FileSystemURL& url,
       const CreateSnapshotFileCallback& callback) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AsyncFileUtil);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_BROWSER_FILEAPI_ASYNC_FILE_UTIL_H_