86 lines
2.8 KiB
C
86 lines
2.8 KiB
C
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// Copyright (c) 2013 Google Inc. All rights reserved.
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// Use of this source code is governed by a BSD-style license tha can be
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// found in the LICENSE file.
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//
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// Defines an abstract file interface.
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#ifndef PACKAGER_FILE_FILE_H_
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#define PACKAGER_FILE_FILE_H_
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#include "base/basictypes.h"
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namespace media {
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extern const char* kLocalFilePrefix;
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class File {
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public:
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// Open the specified file, or return NULL on error.
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// This is actually a file factory method, it opens a proper file, e.g.
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// LocalFile, MemFile automatically based on prefix.
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static File* Open(const char* name, const char* mode);
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// Flush() and de-allocate resources associated with this file, and
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// delete this File object. THIS IS THE ONE TRUE WAY TO DEALLOCATE
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// THIS OBJECT.
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// Returns true on success.
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// For writable files, returning false MAY INDICATE DATA LOSS.
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virtual bool Close() = 0;
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// Reads data and returns it in buffer. Returns a value < 0 on error,
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// or the number of bytes read otherwise. Returns zero on end-of-file,
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// or if 'length' is zero.
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virtual int64 Read(void* buffer, uint64 length) = 0;
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// Write 'length' bytes from 'buffer', returning the number of bytes
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// that were actually written. Return < 0 on error.
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//
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// For a file open in append mode (i.e., "a" or "a+"), Write()
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// always appends to the end of the file. For files opened in other
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// write modes (i.e., "w", or "w+"), writes occur at the
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// current file offset.
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virtual int64 Write(const void* buffer, uint64 length) = 0;
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// Return the size of the file in bytes.
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// A return value less than zero indicates a problem getting the
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// size.
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virtual int64 Size() = 0;
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// Flushes the file so that recently written data will survive an
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// application crash (but not necessarily an OS crash). For
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// instance, in localfile the data is flushed into the OS but not
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// necessarily to disk.
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virtual bool Flush() = 0;
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// Return whether we're currently at eof.
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virtual bool Eof() = 0;
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// ************************************************************
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// * Static Methods: File-on-the-filesystem status
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// ************************************************************
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// Returns the size of a file in bytes, and opens and closes the file
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// in the process. Returns -1 on failure.
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static int64 GetFileSize(const char* fname);
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protected:
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File() {}
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// Do *not* call the destructor directly (with the "delete" keyword)
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// nor use scoped_ptr; instead use Close().
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virtual ~File() {}
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// Internal open. Should not be used directly.
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virtual bool Open() = 0;
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private:
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// This is a file factory method, it creates a proper file, e.g.
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// LocalFile, MemFile based on prefix.
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static File* Create(const char* fname, const char* mode);
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DISALLOW_COPY_AND_ASSIGN(File);
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};
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} // namespace media
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#endif // PACKAGER_FILE_FILE_H_
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