base64.hh 1.96 KB
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/* Copyright 2015 OpenMarket Ltd
 *
 * 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.
 */
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#ifndef OLM_BASE64_HH_
#define OLM_BASE64_HH_
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#include <cstddef>
#include <cstdint>

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namespace olm {
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/**
 * The number of bytes of unpadded base64 needed to encode a length of input.
 */
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static std::size_t encode_base64_length(
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    std::size_t input_length
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) {
    return 4 * ((input_length + 2) / 3) + (input_length + 2) % 3 - 2;
}
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/**
 * Encode the raw input as unpadded base64.
 * Writes encode_base64_length(input_length) bytes to the output buffer.
 * The input can overlap with the last three quarters of the output buffer.
 * That is, the input pointer may be output + output_length - input_length.
 */
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std::uint8_t * encode_base64(
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    std::uint8_t const * input, std::size_t input_length,
    std::uint8_t * output
);

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/**
 * The number of bytes of raw data a length of unpadded base64 will encode to.
 * Returns std::size_t(-1) if the length is not a valid length for base64.
 */
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std::size_t decode_base64_length(
    std::size_t input_length
);

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/**
 * Decodes the unpadded base64 input to raw bytes.
 * Writes decode_base64_length(input_length) bytes to the output buffer.
 * The output can overlap with the first three quarters of the input buffer.
 * That is, the input pointers and output pointer may be the same.
 */
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std::uint8_t const * decode_base64(
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    std::uint8_t const * input, std::size_t input_length,
    std::uint8_t * output
);

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} // namespace olm
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#endif /* OLM_BASE64_HH_ */