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