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
28 // Calculates how long a string will be when it is base64 encoded given its
29 // length and whether or not the result should be padded.
30 size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding);
31
32 // Base64-encodes `src` using the alphabet provided in `base64` and writes the
33 // result to `dest`. If `do_padding` is true, `dest` is padded with '=' chars
34 // until its length is a multiple of 3. Returns the length of `dest`.
35 size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest,
36 size_t szdest, const char* base64, bool do_padding);
37
38 // Base64-encodes `src` using the alphabet provided in `base64` and writes the
39 // result to `dest`. If `do_padding` is true, `dest` is padded with '=' chars
40 // until its length is a multiple of 3.
41 template <typename String>
Base64EscapeInternal(const unsigned char * src,size_t szsrc,String * dest,bool do_padding,const char * base64_chars)42 void Base64EscapeInternal(const unsigned char* src, size_t szsrc, String* dest,
43 bool do_padding, const char* base64_chars) {
44 const size_t calc_escaped_size =
45 CalculateBase64EscapedLenInternal(szsrc, do_padding);
46 STLStringResizeUninitialized(dest, calc_escaped_size);
47
48 const size_t escaped_len = Base64EscapeInternal(
49 src, szsrc, &(*dest)[0], dest->size(), base64_chars, do_padding);
50 assert(calc_escaped_size == escaped_len);
51 dest->erase(escaped_len);
52 }
53
54 } // namespace strings_internal
55 ABSL_NAMESPACE_END
56 } // namespace absl
57
58 #endif // ABSL_STRINGS_INTERNAL_ESCAPING_H_
59