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
|
// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chromeos/components/onc/variable_expander.h"
#include <algorithm>
#include <string_view>
#include "base/containers/flat_map.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/syslog_logging.h"
#include "base/values.h"
namespace {
// Expects ",n" or ",n,m" in |range|. Puts n into |start| and m into |count| if
// present. Returns true if |range| was well formatted and parsing the numbers
// succeeded.
bool ParseRange(std::string_view range, size_t* start, size_t* count) {
std::vector<std::string_view> parts = base::SplitStringPiece(
range, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
DCHECK(!parts.empty());
if (!parts[0].empty())
return false;
if (parts.size() > 1 && !base::StringToSizeT(parts[1], start))
return false;
if (parts.size() > 2 && !base::StringToSizeT(parts[2], count))
return false;
if (parts.size() > 3)
return false;
return true;
}
// Expands all occurrences of a variable with name |variable_name| to
// |replacement| or parts of it. This method handles the following variants:
// - ${variable_name} -> |replacement|
// - ${variable_name,pos} -> |replacement.substr(pos)|
// - ${variable_name,pos,count} -> |replacement.substr(pos,count)|
// Strictly enforces the format (up to whitespace), e.g.
// ${variable_name , 2 , 9 } works, but ${variable_name,2o,9e} doesn't.
// Returns true if no error occurred.
bool Expand(std::string_view variable_name,
std::string_view replacement,
std::string* str) {
std::string token = base::StrCat({"${", variable_name});
size_t token_start = 0;
bool no_error = true;
int count = 0;
while ((token_start = str->find(token, token_start)) != std::string::npos) {
// Exit if |token| is found too often.
if (++count > 100) {
LOG(ERROR) << "Maximum replacement count exceeded for " << variable_name
<< " in string '" << *str << "'";
no_error = false;
break;
}
// Find the closing braces.
const size_t range_start = token_start + token.size();
const size_t range_end = str->find("}", range_start);
if (range_end == std::string::npos) {
LOG(ERROR) << "Closing braces not found for " << variable_name
<< " in string '" << *str << "'";
++token_start;
no_error = false;
continue;
}
// Full variable, e.g. ${machine_name} or ${machine_name,8,3}.
DCHECK_GE(range_end, range_start);
const std::string_view full_token =
std::string_view(*str).substr(token_start, range_end + 1 - token_start);
// Determine if the variable defines a range, e.g. ${machine_name,8,3}.
size_t replacement_start = 0;
size_t replacement_count = std::string::npos;
if (range_end > range_start) {
const std::string_view range =
std::string_view(*str).substr(range_start, range_end - range_start);
if (!ParseRange(range, &replacement_start, &replacement_count)) {
LOG(ERROR) << "Invalid range definition for " << variable_name
<< " in string '" << *str << "'";
token_start += full_token.size();
no_error = false;
continue;
}
}
const std::string_view replacement_part = replacement.substr(
std::min(replacement_start, replacement.size()), replacement_count);
// Don't use ReplaceSubstringsAfterOffset here, it can lead to a doubling
// of tokens, see VariableExpanderTest.DoesNotRecurse test.
base::ReplaceFirstSubstringAfterOffset(str, token_start, full_token,
replacement_part);
token_start += replacement_part.size();
}
return no_error;
}
} // namespace
namespace chromeos {
VariableExpander::VariableExpander(
base::flat_map<std::string, std::string> variables)
: variables_(std::move(variables)) {}
VariableExpander::~VariableExpander() = default;
bool VariableExpander::ExpandString(std::string* str) const {
bool no_error = true;
for (const auto& kv : variables_)
no_error &= Expand(kv.first, kv.second, str);
return no_error;
}
bool VariableExpander::ExpandValue(base::Value* value) const {
bool no_error = true;
switch (value->type()) {
case base::Value::Type::STRING: {
std::string expanded_str = value->GetString();
no_error &= ExpandString(&expanded_str);
*value = base::Value(expanded_str);
break;
}
case base::Value::Type::DICT: {
for (const auto child : value->GetDict()) {
no_error &= ExpandValue(&child.second);
}
break;
}
case base::Value::Type::LIST: {
for (base::Value& child : value->GetList())
no_error &= ExpandValue(&child);
break;
}
case base::Value::Type::BOOLEAN:
case base::Value::Type::INTEGER:
case base::Value::Type::DOUBLE:
case base::Value::Type::BINARY:
case base::Value::Type::NONE: {
// Nothing to do here.
break;
}
}
return no_error;
}
} // namespace chromeos
|
