1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_FILES_FILE_PROXY_H_ 6 #define BASE_FILES_FILE_PROXY_H_ 7 8 #include "base/base_export.h" 9 #include "base/callback_forward.h" 10 #include "base/files/file.h" 11 #include "base/files/file_path.h" 12 #include "base/memory/ref_counted.h" 13 #include "base/memory/weak_ptr.h" 14 15 namespace tracked_objects { 16 class Location; 17 }; 18 19 namespace base { 20 21 class TaskRunner; 22 class Time; 23 24 // This class provides asynchronous access to a File. All methods follow the 25 // same rules of the equivalent File method, as they are implemented by bouncing 26 // the operation to File using a TaskRunner. 27 // 28 // This class performs automatic proxying to close the underlying file at 29 // destruction. 30 // 31 // The TaskRunner is in charge of any sequencing of the operations, but a single 32 // operation can be proxied at a time, regardless of the use of a callback. 33 // In other words, having a sequence like 34 // 35 // proxy.Write(...); 36 // proxy.Write(...); 37 // 38 // means the second Write will always fail. 39 class BASE_EXPORT FileProxy : public SupportsWeakPtr<FileProxy> { 40 public: 41 // This callback is used by methods that report only an error code. It is 42 // valid to pass a null callback to some functions that takes a 43 // StatusCallback, in which case the operation will complete silently. 44 typedef Callback<void(File::Error)> StatusCallback; 45 46 typedef Callback<void(File::Error, 47 const FilePath&)> CreateTemporaryCallback; 48 typedef Callback<void(File::Error, 49 const File::Info&)> GetFileInfoCallback; 50 typedef Callback<void(File::Error, 51 const char* data, 52 int bytes_read)> ReadCallback; 53 typedef Callback<void(File::Error, 54 int bytes_written)> WriteCallback; 55 56 FileProxy(); 57 explicit FileProxy(TaskRunner* task_runner); 58 ~FileProxy(); 59 60 // Creates or opens a file with the given flags. It is invalid to pass a null 61 // callback. If File::FLAG_CREATE is set in |file_flags| it always tries to 62 // create a new file at the given |file_path| and fails if the file already 63 // exists. 64 // 65 // This returns false if task posting to |task_runner| has failed. 66 bool CreateOrOpen(const FilePath& file_path, 67 uint32 file_flags, 68 const StatusCallback& callback); 69 70 // Creates a temporary file for writing. The path and an open file are 71 // returned. It is invalid to pass a null callback. The additional file flags 72 // will be added on top of the default file flags which are: 73 // File::FLAG_CREATE_ALWAYS 74 // File::FLAG_WRITE 75 // File::FLAG_TEMPORARY. 76 // 77 // This returns false if task posting to |task_runner| has failed. 78 bool CreateTemporary(uint32 additional_file_flags, 79 const CreateTemporaryCallback& callback); 80 81 // Returns true if the underlying |file_| is valid. 82 bool IsValid() const; 83 84 // Returns true if a new file was created (or an old one truncated to zero 85 // length to simulate a new file), and false otherwise. 86 bool created() const { return file_.created(); } 87 88 // Claims ownership of |file|. It is an error to call this method when 89 // IsValid() returns true. 90 void SetFile(File file); 91 92 File TakeFile(); 93 94 PlatformFile GetPlatformFile() const; 95 96 // Proxies File::Close. The callback can be null. 97 // This returns false if task posting to |task_runner| has failed. 98 bool Close(const StatusCallback& callback); 99 100 // Proxies File::GetInfo. The callback can't be null. 101 // This returns false if task posting to |task_runner| has failed. 102 bool GetInfo(const GetFileInfoCallback& callback); 103 104 // Proxies File::Read. The callback can't be null. 105 // This returns false if |bytes_to_read| is less than zero, or 106 // if task posting to |task_runner| has failed. 107 bool Read(int64 offset, int bytes_to_read, const ReadCallback& callback); 108 109 // Proxies File::Write. The callback can be null. 110 // This returns false if |bytes_to_write| is less than or equal to zero, 111 // if |buffer| is NULL, or if task posting to |task_runner| has failed. 112 bool Write(int64 offset, 113 const char* buffer, 114 int bytes_to_write, 115 const WriteCallback& callback); 116 117 // Proxies File::SetTimes. The callback can be null. 118 // This returns false if task posting to |task_runner| has failed. 119 bool SetTimes(Time last_access_time, 120 Time last_modified_time, 121 const StatusCallback& callback); 122 123 // Proxies File::SetLength. The callback can be null. 124 // This returns false if task posting to |task_runner| has failed. 125 bool SetLength(int64 length, const StatusCallback& callback); 126 127 // Proxies File::Flush. The callback can be null. 128 // This returns false if task posting to |task_runner| has failed. 129 bool Flush(const StatusCallback& callback); 130 131 private: 132 friend class FileHelper; 133 TaskRunner* task_runner() { return task_runner_.get(); } 134 135 scoped_refptr<TaskRunner> task_runner_; 136 File file_; 137 DISALLOW_COPY_AND_ASSIGN(FileProxy); 138 }; 139 140 } // namespace base 141 142 #endif // BASE_FILES_FILE_PROXY_H_ 143
