1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_RUNTIME_BASE_UNIX_FILE_FD_FILE_H_
18#define ART_RUNTIME_BASE_UNIX_FILE_FD_FILE_H_
19
20#include <fcntl.h>
21#include <string>
22#include "base/unix_file/random_access_file.h"
23#include "base/macros.h"
24
25namespace unix_file {
26
27// If true, check whether Flush and Close are called before destruction.
28static constexpr bool kCheckSafeUsage = true;
29
30// A RandomAccessFile implementation backed by a file descriptor.
31//
32// Not thread safe.
33class FdFile : public RandomAccessFile {
34 public:
35  FdFile();
36  // Creates an FdFile using the given file descriptor. Takes ownership of the
37  // file descriptor. (Use DisableAutoClose to retain ownership.)
38  FdFile(int fd, bool checkUsage);
39  FdFile(int fd, const std::string& path, bool checkUsage);
40  FdFile(int fd, const std::string& path, bool checkUsage, bool read_only_mode);
41
42  // Destroys an FdFile, closing the file descriptor if Close hasn't already
43  // been called. (If you care about the return value of Close, call it
44  // yourself; this is meant to handle failure cases and read-only accesses.
45  // Note though that calling Close and checking its return value is still no
46  // guarantee that data actually made it to stable storage.)
47  virtual ~FdFile();
48
49  // Opens file 'file_path' using 'flags' and 'mode'.
50  bool Open(const std::string& file_path, int flags);
51  bool Open(const std::string& file_path, int flags, mode_t mode);
52
53  // RandomAccessFile API.
54  int Close() OVERRIDE WARN_UNUSED;
55  int64_t Read(char* buf, int64_t byte_count, int64_t offset) const OVERRIDE WARN_UNUSED;
56  int SetLength(int64_t new_length) OVERRIDE WARN_UNUSED;
57  int64_t GetLength() const OVERRIDE;
58  int64_t Write(const char* buf, int64_t byte_count, int64_t offset) OVERRIDE WARN_UNUSED;
59  int Flush() OVERRIDE WARN_UNUSED;
60
61  // Short for SetLength(0); Flush(); Close();
62  void Erase();
63
64  // Try to Flush(), then try to Close(); If either fails, call Erase().
65  int FlushCloseOrErase() WARN_UNUSED;
66
67  // Try to Flush and Close(). Attempts both, but returns the first error.
68  int FlushClose() WARN_UNUSED;
69
70  // Bonus API.
71  int Fd() const;
72  bool ReadOnlyMode() const;
73  bool CheckUsage() const;
74  bool IsOpened() const;
75  const std::string& GetPath() const {
76    return file_path_;
77  }
78  void DisableAutoClose();
79  bool ReadFully(void* buffer, size_t byte_count) WARN_UNUSED;
80  bool PreadFully(void* buffer, size_t byte_count, size_t offset) WARN_UNUSED;
81  bool WriteFully(const void* buffer, size_t byte_count) WARN_UNUSED;
82  bool PwriteFully(const void* buffer, size_t byte_count, size_t offset) WARN_UNUSED;
83
84  // Copy data from another file.
85  bool Copy(FdFile* input_file, int64_t offset, int64_t size);
86  // Clears the file content and resets the file offset to 0.
87  // Returns true upon success, false otherwise.
88  bool ClearContent();
89  // Resets the file offset to the beginning of the file.
90  bool ResetOffset();
91
92  // This enum is public so that we can define the << operator over it.
93  enum class GuardState {
94    kBase,           // Base, file has not been flushed or closed.
95    kFlushed,        // File has been flushed, but not closed.
96    kClosed,         // File has been flushed and closed.
97    kNoCheck         // Do not check for the current file instance.
98  };
99
100  // WARNING: Only use this when you know what you're doing!
101  void MarkUnchecked();
102
103 protected:
104  // If the guard state indicates checking (!=kNoCheck), go to the target state "target". Print the
105  // given warning if the current state is or exceeds warn_threshold.
106  void moveTo(GuardState target, GuardState warn_threshold, const char* warning);
107
108  // If the guard state indicates checking (<kNoCheck), and is below the target state "target", go
109  // to "target." If the current state is higher (excluding kNoCheck) than the trg state, print the
110  // warning.
111  void moveUp(GuardState target, const char* warning);
112
113  // Forcefully sets the state to the given one. This can overwrite kNoCheck.
114  void resetGuard(GuardState new_state) {
115    if (kCheckSafeUsage) {
116      guard_state_ = new_state;
117    }
118  }
119
120  GuardState guard_state_;
121
122 private:
123  template <bool kUseOffset>
124  bool WriteFullyGeneric(const void* buffer, size_t byte_count, size_t offset);
125
126  int fd_;
127  std::string file_path_;
128  bool auto_close_;
129  bool read_only_mode_;
130
131  DISALLOW_COPY_AND_ASSIGN(FdFile);
132};
133
134std::ostream& operator<<(std::ostream& os, const FdFile::GuardState& kind);
135
136}  // namespace unix_file
137
138#endif  // ART_RUNTIME_BASE_UNIX_FILE_FD_FILE_H_
139