1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
//
// Copyright 2017 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.
//
// -----------------------------------------------------------------------------
// File: escaping.h
// -----------------------------------------------------------------------------
//
// This header file contains string utilities involved in escaping and
// unescaping strings in various ways.
#ifndef ABSL_STRINGS_ESCAPING_H_
#define ABSL_STRINGS_ESCAPING_H_
#include <cstddef>
#include <string>
#include <vector>
#include "absl/base/macros.h"
#include "absl/strings/ascii.h"
#include "absl/strings/str_join.h"
#include "absl/strings/string_view.h"
namespace absl {
inline namespace lts_2019_08_08 {
// CUnescape()
//
// Unescapes a `source` string and copies it into `dest`, rewriting C-style
// escape sequences (https://en.cppreference.com/w/cpp/language/escape) into
// their proper code point equivalents, returning `true` if successful.
//
// The following unescape sequences can be handled:
//
// * ASCII escape sequences ('\n','\r','\\', etc.) to their ASCII equivalents
// * Octal escape sequences ('\nnn') to byte nnn. The unescaped value must
// resolve to a single byte or an error will occur. E.g. values greater than
// 0xff will produce an error.
// * Hexadecimal escape sequences ('\xnn') to byte nn. While an arbitrary
// number of following digits are allowed, the unescaped value must resolve
// to a single byte or an error will occur. E.g. '\x0045' is equivalent to
// '\x45', but '\x1234' will produce an error.
// * Unicode escape sequences ('\unnnn' for exactly four hex digits or
// '\Unnnnnnnn' for exactly eight hex digits, which will be encoded in
// UTF-8. (E.g., `\u2019` unescapes to the three bytes 0xE2, 0x80, and
// 0x99).
//
// If any errors are encountered, this function returns `false`, leaving the
// `dest` output parameter in an unspecified state, and stores the first
// encountered error in `error`. To disable error reporting, set `error` to
// `nullptr` or use the overload with no error reporting below.
//
// Example:
//
// std::string s = "foo\\rbar\\nbaz\\t";
// std::string unescaped_s;
// if (!absl::CUnescape(s, &unescaped_s) {
// ...
// }
// EXPECT_EQ(unescaped_s, "foo\rbar\nbaz\t");
bool CUnescape(absl::string_view source, std::string* dest, std::string* error);
// Overload of `CUnescape()` with no error reporting.
inline bool CUnescape(absl::string_view source, std::string* dest) {
return CUnescape(source, dest, nullptr);
}
// CEscape()
//
// Escapes a 'src' string using C-style escapes sequences
// (https://en.cppreference.com/w/cpp/language/escape), escaping other
// non-printable/non-whitespace bytes as octal sequences (e.g. "\377").
//
// Example:
//
// std::string s = "foo\rbar\tbaz\010\011\012\013\014\x0d\n";
// std::string escaped_s = absl::CEscape(s);
// EXPECT_EQ(escaped_s, "foo\\rbar\\tbaz\\010\\t\\n\\013\\014\\r\\n");
std::string CEscape(absl::string_view src);
// CHexEscape()
//
// Escapes a 'src' string using C-style escape sequences, escaping
// other non-printable/non-whitespace bytes as hexadecimal sequences (e.g.
// "\xFF").
//
// Example:
//
// std::string s = "foo\rbar\tbaz\010\011\012\013\014\x0d\n";
// std::string escaped_s = absl::CHexEscape(s);
// EXPECT_EQ(escaped_s, "foo\\rbar\\tbaz\\x08\\t\\n\\x0b\\x0c\\r\\n");
std::string CHexEscape(absl::string_view src);
// Utf8SafeCEscape()
//
// Escapes a 'src' string using C-style escape sequences, escaping bytes as
// octal sequences, and passing through UTF-8 characters without conversion.
// I.e., when encountering any bytes with their high bit set, this function
// will not escape those values, whether or not they are valid UTF-8.
std::string Utf8SafeCEscape(absl::string_view src);
// Utf8SafeCHexEscape()
//
// Escapes a 'src' string using C-style escape sequences, escaping bytes as
// hexadecimal sequences, and passing through UTF-8 characters without
// conversion.
std::string Utf8SafeCHexEscape(absl::string_view src);
// Base64Unescape()
//
// Converts a `src` string encoded in Base64 to its binary equivalent, writing
// it to a `dest` buffer, returning `true` on success. If `src` contains invalid
// characters, `dest` is cleared and returns `false`.
bool Base64Unescape(absl::string_view src, std::string* dest);
// WebSafeBase64Unescape()
//
// Converts a `src` string encoded in Base64 to its binary equivalent, writing
// it to a `dest` buffer, but using '-' instead of '+', and '_' instead of '/'.
// If `src` contains invalid characters, `dest` is cleared and returns `false`.
bool WebSafeBase64Unescape(absl::string_view src, std::string* dest);
// Base64Escape()
//
// Encodes a `src` string into a base64-encoded string, with padding characters.
// This function conforms with RFC 4648 section 4 (base64).
void Base64Escape(absl::string_view src, std::string* dest);
std::string Base64Escape(absl::string_view src);
// WebSafeBase64Escape()
//
// Encodes a `src` string into a base64-like string, using '-' instead of '+'
// and '_' instead of '/', and without padding. This function conforms with RFC
// 4648 section 5 (base64url).
void WebSafeBase64Escape(absl::string_view src, std::string* dest);
std::string WebSafeBase64Escape(absl::string_view src);
// HexStringToBytes()
//
// Converts an ASCII hex string into bytes, returning binary data of length
// `from.size()/2`.
std::string HexStringToBytes(absl::string_view from);
// BytesToHexString()
//
// Converts binary data into an ASCII text string, returning a string of size
// `2*from.size()`.
std::string BytesToHexString(absl::string_view from);
} // inline namespace lts_2019_08_08
} // namespace absl
#endif // ABSL_STRINGS_ESCAPING_H_
|
