blob: 16cd44f4efa3720f8495352d9ea65f2d1b02a839 [file] [log] [blame]
* Copyright (C) 2009 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <fcntl.h>
#include <string>
#include "base/unix_file/random_access_file.h"
#include "base/macros.h"
namespace unix_file {
// If true, check whether Flush and Close are called before destruction.
static constexpr bool kCheckSafeUsage = true;
// A RandomAccessFile implementation backed by a file descriptor.
// Not thread safe.
class FdFile : public RandomAccessFile {
// Creates an FdFile using the given file descriptor. Takes ownership of the
// file descriptor. (Use DisableAutoClose to retain ownership.)
FdFile(int fd, bool checkUsage);
FdFile(int fd, const std::string& path, bool checkUsage);
FdFile(int fd, const std::string& path, bool checkUsage, bool read_only_mode);
// Destroys an FdFile, closing the file descriptor if Close hasn't already
// been called. (If you care about the return value of Close, call it
// yourself; this is meant to handle failure cases and read-only accesses.
// Note though that calling Close and checking its return value is still no
// guarantee that data actually made it to stable storage.)
virtual ~FdFile();
// Opens file 'file_path' using 'flags' and 'mode'.
bool Open(const std::string& file_path, int flags);
bool Open(const std::string& file_path, int flags, mode_t mode);
// RandomAccessFile API.
int64_t Read(char* buf, int64_t byte_count, int64_t offset) const OVERRIDE WARN_UNUSED;
int SetLength(int64_t new_length) OVERRIDE WARN_UNUSED;
int64_t GetLength() const OVERRIDE;
int64_t Write(const char* buf, int64_t byte_count, int64_t offset) OVERRIDE WARN_UNUSED;
// Short for SetLength(0); Flush(); Close();
void Erase();
// Try to Flush(), then try to Close(); If either fails, call Erase().
int FlushCloseOrErase() WARN_UNUSED;
// Try to Flush and Close(). Attempts both, but returns the first error.
int FlushClose() WARN_UNUSED;
// Bonus API.
int Fd() const;
bool ReadOnlyMode() const;
bool CheckUsage() const;
bool IsOpened() const;
const std::string& GetPath() const {
return file_path_;
void DisableAutoClose();
bool ReadFully(void* buffer, size_t byte_count) WARN_UNUSED;
bool PreadFully(void* buffer, size_t byte_count, size_t offset) WARN_UNUSED;
bool WriteFully(const void* buffer, size_t byte_count) WARN_UNUSED;
bool PwriteFully(const void* buffer, size_t byte_count, size_t offset) WARN_UNUSED;
// Copy data from another file.
bool Copy(FdFile* input_file, int64_t offset, int64_t size);
// Clears the file content and resets the file offset to 0.
// Returns true upon success, false otherwise.
bool ClearContent();
// Resets the file offset to the beginning of the file.
bool ResetOffset();
// This enum is public so that we can define the << operator over it.
enum class GuardState {
kBase, // Base, file has not been flushed or closed.
kFlushed, // File has been flushed, but not closed.
kClosed, // File has been flushed and closed.
kNoCheck // Do not check for the current file instance.
// WARNING: Only use this when you know what you're doing!
void MarkUnchecked();
// If the guard state indicates checking (!=kNoCheck), go to the target state "target". Print the
// given warning if the current state is or exceeds warn_threshold.
void moveTo(GuardState target, GuardState warn_threshold, const char* warning);
// If the guard state indicates checking (<kNoCheck), and is below the target state "target", go
// to "target." If the current state is higher (excluding kNoCheck) than the trg state, print the
// warning.
void moveUp(GuardState target, const char* warning);
// Forcefully sets the state to the given one. This can overwrite kNoCheck.
void resetGuard(GuardState new_state) {
if (kCheckSafeUsage) {
guard_state_ = new_state;
GuardState guard_state_;
template <bool kUseOffset>
bool WriteFullyGeneric(const void* buffer, size_t byte_count, size_t offset);
int fd_;
std::string file_path_;
bool auto_close_;
bool read_only_mode_;
std::ostream& operator<<(std::ostream& os, const FdFile::GuardState& kind);
} // namespace unix_file