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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_BASE_UPLOAD_ELEMENT_READER_H_
#define NET_BASE_UPLOAD_ELEMENT_READER_H_
#include <stdint.h>
#include "net/base/completion_once_callback.h"
#include "net/base/net_export.h"
namespace net {
class IOBuffer;
// An interface to read an upload data element.
class NET_EXPORT UploadElementReader {
public:
UploadElementReader() = default;
UploadElementReader(const UploadElementReader&) = delete;
UploadElementReader& operator=(const UploadElementReader&) = delete;
virtual ~UploadElementReader() = default;
// This function must be called before calling any other method. It is not
// valid to call any method (other than the destructor) if Init() fails.
// This method can be called multiple times. Calling this results in resetting
// the state (i.e. the stream is rewound), and any previously pending Init()
// or Read() calls are aborted.
//
// Initializes the instance synchronously when possible, otherwise does
// initialization aynschronously, returns ERR_IO_PENDING and runs callback.
// Calling this method again after a Init() success results in resetting the
// state.
virtual int Init(CompletionOnceCallback callback) = 0;
// Returns the byte-length of the element. For files that do not exist, 0
// is returned. This is done for consistency with Mozilla.
virtual uint64_t GetContentLength() const = 0;
// Returns the number of bytes remaining to read.
virtual uint64_t BytesRemaining() const = 0;
// Returns true if the upload element is entirely in memory.
// The default implementation returns false.
virtual bool IsInMemory() const;
// Reads up to |buf_length| bytes synchronously and returns the number of
// bytes read or error code when possible, otherwise, returns ERR_IO_PENDING
// and runs |callback| with the result. |buf_length| must be greater than 0.
virtual int Read(IOBuffer* buf,
int buf_length,
CompletionOnceCallback callback) = 0;
};
} // namespace net
#endif // NET_BASE_UPLOAD_ELEMENT_READER_H_
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