114 lines
4.4 KiB
C++
114 lines
4.4 KiB
C++
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef RTC_BASE_SYSTEM_FILE_WRAPPER_H_
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#define RTC_BASE_SYSTEM_FILE_WRAPPER_H_
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#include <stddef.h>
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#include <stdio.h>
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#include <string>
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// Implementation that can read (exclusive) or write from/to a file.
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namespace webrtc {
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// This class is a thin wrapper around FILE*. It's main features are that it
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// owns the FILE*, calling fclose on destruction, and that on windows, file
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// names passed to the open methods are always treated as utf-8, regardless of
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// system code page.
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// Most of the methods return only a success/fail indication. When needed, an
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// optional argument |int* error| should be added to all methods, in the same
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// way as for the OpenWriteOnly methods.
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class FileWrapper final {
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public:
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// Opens a file, in read or write mode. Use the is_open() method on the
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// returned object to check if the open operation was successful. On failure,
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// and if |error| is non-null, the system errno value is stored at |*error|.
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// The file is closed by the destructor.
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static FileWrapper OpenReadOnly(const char* file_name_utf8);
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static FileWrapper OpenReadOnly(const std::string& file_name_utf8);
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static FileWrapper OpenWriteOnly(const char* file_name_utf8,
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int* error = nullptr);
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static FileWrapper OpenWriteOnly(const std::string& file_name_utf8,
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int* error = nullptr);
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FileWrapper() = default;
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// Takes over ownership of |file|, closing it on destruction. Calling with
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// null |file| is allowed, and results in a FileWrapper with is_open() false.
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explicit FileWrapper(FILE* file) : file_(file) {}
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~FileWrapper() { Close(); }
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// Copying is not supported.
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FileWrapper(const FileWrapper&) = delete;
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FileWrapper& operator=(const FileWrapper&) = delete;
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// Support for move semantics.
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FileWrapper(FileWrapper&&);
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FileWrapper& operator=(FileWrapper&&);
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// Returns true if a file has been opened. If the file is not open, no methods
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// but is_open and Close may be called.
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bool is_open() const { return file_ != nullptr; }
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// Closes the file, and implies Flush. Returns true on success, false if
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// writing buffered data fails. On failure, the file is nevertheless closed.
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// Calling Close on an already closed file does nothing and returns success.
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bool Close();
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// Releases and returns the wrapped file without closing it. This call passes
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// the ownership of the file to the caller, and the wrapper is no longer
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// responsible for closing it. Similarly the previously wrapped file is no
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// longer available for the wrapper to use in any aspect.
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FILE* Release();
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// Write any buffered data to the underlying file. Returns true on success,
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// false on write error. Note: Flushing when closing, is not required.
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bool Flush();
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// Seeks to the beginning of file. Returns true on success, false on failure,
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// e.g., if the underlying file isn't seekable.
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bool Rewind() { return SeekTo(0); }
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// TODO(nisse): The seek functions are used only by the WavReader. If that
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// code is demoted to test code, seek functions can be deleted from this
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// utility.
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// Seek relative to current file position.
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bool SeekRelative(int64_t offset);
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// Seek to given position.
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bool SeekTo(int64_t position);
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// Returns the file size or -1 if a size could not be determined.
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// (A file size might not exists for non-seekable files or file-like
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// objects, for example /dev/tty on unix.)
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long FileSize();
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// Returns number of bytes read. Short count indicates EOF or error.
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size_t Read(void* buf, size_t length);
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// If the most recent Read() returned a short count, this methods returns true
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// if the short count was due to EOF, and false it it was due to some i/o
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// error.
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bool ReadEof() const;
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// Returns true if all data was successfully written (or buffered), or false
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// if there was an error. Writing buffered data can fail later, and is
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// reported with return value from Flush or Close.
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bool Write(const void* buf, size_t length);
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private:
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FILE* file_ = nullptr;
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};
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} // namespace webrtc
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#endif // RTC_BASE_SYSTEM_FILE_WRAPPER_H_
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