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// Copyright 2019 Google Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include "tink/util/buffer.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
// Abstract interface for streams that provide random access for reading,
// like regular files.
class RandomAccessStream {
RandomAccessStream() {}
virtual ~RandomAccessStream() {}
// Reads up to 'count' bytes starting at 'position' and writes them
// to 'dest_buffer'. 'position' must be within the size of the stream,
// 'count' must be positive, 'dest_buffer' must be non-NULL and its
// allocated size must be not smaller than 'count'.
// Return values:
// OK: if exactly 'count' bytes were read and written to 'dest_buffer',
// or if fewer than 'count' (potentially 0) bytes were read,
// but the lack of bytes is not permanent, and retrying may succeed;
// in this case 'dest_buffer' contains the read bytes, and the size
// of the buffer has been changed to the number of bytes read.
// OUT_OF_RANGE: if the end of stream has been reached;
// in this case 'dest_buffer' contains the bytes read till the end
// of the stream (if any). This status is returned also when
// 'position' is larger than the current size of the stream.
// INVALID_ARGUMENT: if some of the arguments are not valid.
// other: if some other error occurred.
virtual crypto::tink::util::Status PRead(
int64_t position,
int count,
crypto::tink::util::Buffer* dest_buffer) = 0;
// Returns the size of this stream in bytes, if available.
// If the size is not available, returns a non-Ok status.
// The returned value is the "logical" size of a stream, i.e. of
// a sequence of bytes), stating how many bytes are there in the sequence.
// For a successful PRead-operation the starting position should be
// in the range 0..size()-1 (otherwise PRead may return a non-Ok status).
virtual crypto::tink::util::StatusOr<int64_t> size() = 0;
} // namespace tink
} // namespace crypto