chromium/third_party/abseil-cpp/absl/strings/internal/escaping.cc

// Copyright 2020 The Abseil Authors.
//
// 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
//
//      https://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.

#include "absl/strings/internal/escaping.h"

#include <limits>

#include "absl/base/internal/endian.h"
#include "absl/base/internal/raw_logging.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace strings_internal {

// The two strings below provide maps from normal 6-bit characters to their
// base64-escaped equivalent.
// For the inverse case, see kUn(WebSafe)Base64 in the external
// escaping.cc.
ABSL_CONST_INIT const char kBase64Chars[] = …;

ABSL_CONST_INIT const char kWebSafeBase64Chars[] = …;

size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding) { … }

// ----------------------------------------------------------------------
//   Take the input in groups of 4 characters and turn each
//   character into a code 0 to 63 thus:
//           A-Z map to 0 to 25
//           a-z map to 26 to 51
//           0-9 map to 52 to 61
//           +(- for WebSafe) maps to 62
//           /(_ for WebSafe) maps to 63
//   There will be four numbers, all less than 64 which can be represented
//   by a 6 digit binary number (aaaaaa, bbbbbb, cccccc, dddddd respectively).
//   Arrange the 6 digit binary numbers into three bytes as such:
//   aaaaaabb bbbbcccc ccdddddd
//   Equals signs (one or two) are used at the end of the encoded block to
//   indicate that the text was not an integer multiple of three bytes long.
// ----------------------------------------------------------------------
size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest,
                            size_t szdest, const char* base64,
                            bool do_padding) { … }

}  // namespace strings_internal
ABSL_NAMESPACE_END
}  // namespace absl