| // 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 |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #ifndef TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_ |
| #define TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_ |
| |
| #include <memory> |
| #include <vector> |
| |
| #include "tink/input_stream.h" |
| #include "tink/util/status.h" |
| #include "tink/util/statusor.h" |
| |
| namespace crypto { |
| namespace tink { |
| namespace streamingaead { |
| |
| // An InputStream that initially buffers all the read bytes, and offers |
| // rewind-functionality, until explicitly instructed to disable |
| // rewinding (and stop buffering). |
| class BufferedInputStream : public crypto::tink::InputStream { |
| public: |
| // Constructs an InputStream that will read from 'input_stream', |
| // buffering all the read bytes in memory, and offering rewinding |
| // to the beginning of the stream (as long as rewinding is enabled). |
| explicit BufferedInputStream( |
| std::unique_ptr<crypto::tink::InputStream> input_stream); |
| |
| ~BufferedInputStream() override; |
| |
| crypto::tink::util::StatusOr<int> Next(const void** data) override; |
| |
| void BackUp(int count) override; |
| |
| int64_t Position() const override; |
| |
| // Rewinds this stream to the beginning (if rewinding is still enabled). |
| crypto::tink::util::Status Rewind(); |
| |
| // Disables rewinding. |
| void DisableRewinding(); |
| |
| private: |
| std::unique_ptr<crypto::tink::InputStream> input_stream_; |
| bool direct_access_; // true iff we don't buffer any data any more |
| |
| // The fields below are valid and in use iff direct_access_ is false. |
| // Once direct_access_ becomes true, all the calls to this stream's methods |
| // are directly relayed to methods of input_stream_. |
| crypto::tink::util::Status status_; |
| std::vector<uint8_t> buffer_; |
| bool after_rewind_; // true iff no Next has been called after rewind |
| bool rewinding_enabled_; // true iff this stream can be rewound |
| int64_t position_; // current position in the stream (from the beginning) |
| |
| // Counters that describe the state of the data in buffer_. |
| int count_in_buffer_; // # of bytes available in buffer_ |
| int count_backedup_; // # of bytes available in buffer_ that were backed up |
| int buffer_offset_; // offset at which the returned bytes start in buffer_ |
| }; |
| |
| } // namespace streamingaead |
| } // namespace tink |
| } // namespace crypto |
| |
| #endif // TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_ |