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>
Base64EscapeInternal(const unsigned char * src,size_t szsrc,String * dest,bool do_padding,const char * base64_chars)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_
58