storage/browser/file_system/file_system_file_util.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef STORAGE_BROWSER_FILE_SYSTEM_FILE_SYSTEM_FILE_UTIL_H_
#define STORAGE_BROWSER_FILE_SYSTEM_FILE_SYSTEM_FILE_UTIL_H_

#include <stdint.h>

#include <memory>

#include "base/component_export.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "storage/browser/blob/scoped_file.h"
#include "storage/browser/file_system/file_system_operation.h"

namespace base {
class Time;
}

namespace storage {

class FileSystemOperationContext;
class FileSystemURL;

// A file utility interface that provides basic file utility methods for
// FileSystem API.
//
// Layering structure of the FileSystemFileUtil was split out.
// See http://crbug.com/128136 if you need it.
class COMPONENT_EXPORT(STORAGE_BROWSER) FileSystemFileUtil {
 public:
  using CopyOrMoveOptionSet = FileSystemOperation::CopyOrMoveOptionSet;

  // It will be implemented by each subclass such as FileSystemFileEnumerator.
  class COMPONENT_EXPORT(STORAGE_BROWSER) AbstractFileEnumerator {
   public:
    virtual ~AbstractFileEnumerator() = default;

    // Returns an empty path if there are no more results.
    virtual base::FilePath Next() = 0;

    // Returns any file system error met during enumeration. It returns
    // base::File::FILE_OK if enumeration stopped naturally (without error),
    // even if the enumeration produced no results.
    //
    // Precondition: Next() was already called, at least once, and it most
    // recently returned an empty path.
    //
    // TODO(b/329523214): in the long term, this should be a pure virtual
    // method: "virtual base::File::Error GetError() = 0;".
    virtual base::File::Error GetError();

    // These methods return metadata for the file most recently returned by
    // Next(). If Next() has never been called, or if Next() most recently
    // returned an empty string, then return the default values of 0,
    // "null time", and false, respectively.
    virtual int64_t Size() = 0;
    virtual base::Time LastModifiedTime() = 0;
    virtual bool IsDirectory() = 0;
  };

  class COMPONENT_EXPORT(STORAGE_BROWSER) EmptyFileEnumerator
      : public AbstractFileEnumerator {
    base::FilePath Next() override;
    base::File::Error GetError() override;
    int64_t Size() override;
    base::Time LastModifiedTime() override;
    bool IsDirectory() override;
  };

  FileSystemFileUtil(const FileSystemFileUtil&) = delete;
  FileSystemFileUtil& operator=(const FileSystemFileUtil&) = delete;
  virtual ~FileSystemFileUtil() = default;

  // Creates or opens a file with the given flags.
  // See header comments for AsyncFileUtil::CreateOrOpen() for more details.
  // This is used only by Pepper/NaCl File API.
  virtual base::File CreateOrOpen(FileSystemOperationContext* context,
                                  const FileSystemURL& url,
                                  int file_flags) = 0;

  // Ensures that the given |url| exist.  This creates a empty new file
  // at |url| if the |url| does not exist.
  // See header comments for AsyncFileUtil::EnsureFileExists() for more details.
  virtual base::File::Error EnsureFileExists(
      FileSystemOperationContext* context,
      const FileSystemURL& url,
      bool* created) = 0;

  // Creates directory at given url.
  // See header comments for AsyncFileUtil::CreateDirectory() for more details.
  virtual base::File::Error CreateDirectory(FileSystemOperationContext* context,
                                            const FileSystemURL& url,
                                            bool exclusive,
                                            bool recursive) = 0;

  // Retrieves the information about a file.
  // See header comments for AsyncFileUtil::GetFileInfo() for more details.
  virtual base::File::Error GetFileInfo(FileSystemOperationContext* context,
                                        const FileSystemURL& url,
                                        base::File::Info* file_info,
                                        base::FilePath* platform_path) = 0;

  // Returns a pointer to a new instance of AbstractFileEnumerator which is
  // implemented for each FileSystemFileUtil subclass. The instance needs to be
  // freed by the caller, and its lifetime should not extend past when the
  // current call returns to the main FILE message loop.
  //
  // The supplied context must remain valid at least lifetime of the enumerator
  // instance. |this| must remain valid through the lifetime of the created
  // enumerator instance.
  virtual std::unique_ptr<AbstractFileEnumerator> CreateFileEnumerator(
      FileSystemOperationContext* context,
      const FileSystemURL& root_url,
      bool recursive) = 0;

  // Maps |file_system_url| given |context| into |local_file_path|
  // which represents physical file location on the host OS.
  // This may not always make sense for all subclasses.
  virtual base::File::Error GetLocalFilePath(
      FileSystemOperationContext* context,
      const FileSystemURL& file_system_url,
      base::FilePath* local_file_path) = 0;

  // Updates the file metadata information.
  // See header comments for AsyncFileUtil::Touch() for more details.
  virtual base::File::Error Touch(FileSystemOperationContext* context,
                                  const FileSystemURL& url,
                                  const base::Time& last_access_time,
                                  const base::Time& last_modified_time) = 0;

  // Truncates a file to the given length.
  // See header comments for AsyncFileUtil::Truncate() for more details.
  virtual base::File::Error Truncate(FileSystemOperationContext* context,
                                     const FileSystemURL& url,
                                     int64_t length) = 0;

  // Copies a single file or moves a single file or directory from |src_url| to
  // |dest_url|. Whether moving a directory is supported is
  // implementation-defined. The filesystem type of |src_url| and |dest_url|
  // MUST be same. For |option|, please see file_system_operation.h
  //
  // This returns:
  // - File::FILE_ERROR_NOT_FOUND if |src_url|
  //   or the parent directory of |dest_url| does not exist.
  // - File::FILE_ERROR_NOT_A_FILE if |src_url| exists but is not a file and the
  //   operation is copy or the implementation does not support moving
  //   directories.
  // - File::FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
  //   is not a file.
  // - File::FILE_ERROR_FAILED if |dest_url| does not exist and
  //   its parent path is a file.
  //
  virtual base::File::Error CopyOrMoveFile(FileSystemOperationContext* context,
                                           const FileSystemURL& src_url,
                                           const FileSystemURL& dest_url,
                                           CopyOrMoveOptionSet options,
                                           bool copy) = 0;

  // Copies in a single file from a different filesystem.
  // See header comments for AsyncFileUtil::CopyInForeignFile() for
  // more details.
  virtual base::File::Error CopyInForeignFile(
      FileSystemOperationContext* context,
      const base::FilePath& src_file_path,
      const FileSystemURL& dest_url) = 0;

  // Deletes a single file.
  // See header comments for AsyncFileUtil::DeleteFile() for more details.
  virtual base::File::Error DeleteFile(FileSystemOperationContext* context,
                                       const FileSystemURL& url) = 0;

  // Deletes a single empty directory.
  // See header comments for AsyncFileUtil::DeleteDirectory() for more details.
  virtual base::File::Error DeleteDirectory(FileSystemOperationContext* context,
                                            const FileSystemURL& url) = 0;

  // Creates a local snapshot file for a given |url| and returns the
  // metadata and platform path of the snapshot file via |callback|.
  //
  // See header comments for AsyncFileUtil::CreateSnapshotFile() for
  // more details.
  virtual ScopedFile CreateSnapshotFile(FileSystemOperationContext* context,
                                        const FileSystemURL& url,
                                        base::File::Error* error,
                                        base::File::Info* file_info,
                                        base::FilePath* platform_path) = 0;

 protected:
  FileSystemFileUtil() = default;
};

}  // namespace storage

#endif  // STORAGE_BROWSER_FILE_SYSTEM_FILE_SYSTEM_FILE_UTIL_H_