escaping.h (2334B)
1 // Copyright 2020 The Abseil Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef ABSL_STRINGS_INTERNAL_ESCAPING_H_ 16 #define ABSL_STRINGS_INTERNAL_ESCAPING_H_ 17 18 #include <cassert> 19 20 #include "absl/strings/internal/resize_uninitialized.h" 21 22 namespace absl { 23 ABSL_NAMESPACE_BEGIN 24 namespace strings_internal { 25 26 ABSL_CONST_INIT extern const char kBase64Chars[]; 27 ABSL_CONST_INIT extern const char kWebSafeBase64Chars[]; 28 29 // Calculates the length of a Base64 encoding (RFC 4648) of a string of length 30 // `input_len`, with or without padding per `do_padding`. Note that 'web-safe' 31 // encoding (section 5 of the RFC) does not change this length. 32 size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding); 33 34 // Base64-encodes `src` using the alphabet provided in `base64` (which 35 // determines whether to do web-safe encoding or not) and writes the result to 36 // `dest`. If `do_padding` is true, `dest` is padded with '=' chars until its 37 // length is a multiple of 3. Returns the length of `dest`. 38 size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest, 39 size_t szdest, const char* base64, bool do_padding); 40 template <typename String> 41 void Base64EscapeInternal(const unsigned char* src, size_t szsrc, String* dest, 42 bool do_padding, const char* base64_chars) { 43 const size_t calc_escaped_size = 44 CalculateBase64EscapedLenInternal(szsrc, do_padding); 45 STLStringResizeUninitialized(dest, calc_escaped_size); 46 47 const size_t escaped_len = Base64EscapeInternal( 48 src, szsrc, &(*dest)[0], dest->size(), base64_chars, do_padding); 49 assert(calc_escaped_size == escaped_len); 50 dest->erase(escaped_len); 51 } 52 53 } // namespace strings_internal 54 ABSL_NAMESPACE_END 55 } // namespace absl 56 57 #endif // ABSL_STRINGS_INTERNAL_ESCAPING_H_