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https://github.com/abseil/abseil-cpp.git
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cd0423dc25
be exported. The one function that is currently using it is easily implemented with absl::Base64Escape(). PiperOrigin-RevId: 900830658 Change-Id: I859d67efafd5ba96921bb75c9207438975d055d6
69 lines
2.4 KiB
C++
69 lines
2.4 KiB
C++
// Copyright 2020 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/strings/internal/escaping.h"
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#include <limits>
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#include "absl/base/internal/endian.h"
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#include "absl/base/internal/raw_logging.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace strings_internal {
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size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding) {
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// Base64 encodes three bytes of input at a time. If the input is not
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// divisible by three, we pad as appropriate.
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//
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// Base64 encodes each three bytes of input into four bytes of output.
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constexpr size_t kMaxSize = (std::numeric_limits<size_t>::max() - 1) / 4 * 3;
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ABSL_INTERNAL_CHECK(input_len <= kMaxSize,
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"CalculateBase64EscapedLenInternal() overflow");
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size_t len = (input_len / 3) * 4;
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// Since all base 64 input is an integral number of octets, only the following
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// cases can arise:
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if (input_len % 3 == 0) {
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// (from https://tools.ietf.org/html/rfc3548)
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// (1) the final quantum of encoding input is an integral multiple of 24
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// bits; here, the final unit of encoded output will be an integral
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// multiple of 4 characters with no "=" padding,
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} else if (input_len % 3 == 1) {
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// (from https://tools.ietf.org/html/rfc3548)
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// (2) the final quantum of encoding input is exactly 8 bits; here, the
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// final unit of encoded output will be two characters followed by two
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// "=" padding characters, or
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len += 2;
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if (do_padding) {
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len += 2;
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}
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} else { // (input_len % 3 == 2)
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// (from https://tools.ietf.org/html/rfc3548)
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// (3) the final quantum of encoding input is exactly 16 bits; here, the
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// final unit of encoded output will be three characters followed by one
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// "=" padding character.
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len += 3;
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if (do_padding) {
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len += 1;
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}
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}
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return len;
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}
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} // namespace strings_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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