1 // Copyright 2018 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/test/metrics/histogram_enum_reader.h"
6
7 #include "base/files/file_path.h"
8 #include "base/files/file_util.h"
9 #include "base/path_service.h"
10 #include "base/strings/string_number_conversions.h"
11 #include "testing/gtest/include/gtest/gtest.h"
12 #include "third_party/abseil-cpp/absl/types/optional.h"
13 #include "third_party/libxml/chromium/xml_reader.h"
14
15 namespace base {
16 namespace {
17
18 // This is a helper function to the ReadEnumFromHistogramsXml().
19 // Extracts single enum (with integer values) from histograms.xml.
20 // Expects |reader| to point at given enum.
21 // Returns map { value => label } on success, and nullopt on failure.
ParseEnumFromHistogramsXml(const std::string & enum_name,XmlReader * reader)22 absl::optional<HistogramEnumEntryMap> ParseEnumFromHistogramsXml(
23 const std::string& enum_name,
24 XmlReader* reader) {
25 int entries_index = -1;
26
27 HistogramEnumEntryMap result;
28 bool success = true;
29
30 while (true) {
31 const std::string node_name = reader->NodeName();
32 if (node_name == "enum" && reader->IsClosingElement())
33 break;
34
35 if (node_name == "int") {
36 ++entries_index;
37 std::string value_str;
38 std::string label;
39 const bool has_value = reader->NodeAttribute("value", &value_str);
40 const bool has_label = reader->NodeAttribute("label", &label);
41 if (!has_value) {
42 ADD_FAILURE() << "Bad " << enum_name << " enum entry (at index "
43 << entries_index << ", label='" << label
44 << "'): No 'value' attribute.";
45 success = false;
46 }
47 if (!has_label) {
48 ADD_FAILURE() << "Bad " << enum_name << " enum entry (at index "
49 << entries_index << ", value_str='" << value_str
50 << "'): No 'label' attribute.";
51 success = false;
52 }
53
54 HistogramBase::Sample value;
55 if (has_value && !StringToInt(value_str, &value)) {
56 ADD_FAILURE() << "Bad " << enum_name << " enum entry (at index "
57 << entries_index << ", label='" << label
58 << "', value_str='" << value_str
59 << "'): 'value' attribute is not integer.";
60 success = false;
61 }
62 if (result.count(value)) {
63 ADD_FAILURE() << "Bad " << enum_name << " enum entry (at index "
64 << entries_index << ", label='" << label
65 << "', value_str='" << value_str
66 << "'): duplicate value '" << value_str
67 << "' found in enum. The previous one has label='"
68 << result[value] << "'.";
69 success = false;
70 }
71 if (success)
72 result[value] = label;
73 }
74 // All enum entries are on the same level, so it is enough to iterate
75 // until possible.
76 reader->Next();
77 }
78 if (success)
79 return result;
80 return absl::nullopt;
81 }
82
83 } // namespace
84
ReadEnumFromEnumsXml(const std::string & enum_name,const absl::optional<std::string> & subdirectory)85 absl::optional<HistogramEnumEntryMap> ReadEnumFromEnumsXml(
86 const std::string& enum_name,
87 const absl::optional<std::string>& subdirectory) {
88 FilePath src_root;
89 if (!PathService::Get(DIR_SRC_TEST_DATA_ROOT, &src_root)) {
90 ADD_FAILURE() << "Failed to get src root.";
91 return absl::nullopt;
92 }
93
94 base::FilePath enums_xml =
95 src_root.AppendASCII("tools").AppendASCII("metrics").AppendASCII(
96 "histograms");
97 if (subdirectory) {
98 enums_xml =
99 enums_xml.AppendASCII("metadata").AppendASCII(subdirectory.value());
100 }
101 enums_xml = enums_xml.AppendASCII("enums.xml");
102
103 if (!PathExists(enums_xml)) {
104 ADD_FAILURE() << "enums.xml file does not exist.";
105 return absl::nullopt;
106 }
107
108 XmlReader enums_xml_reader;
109 if (!enums_xml_reader.LoadFile(enums_xml.MaybeAsASCII())) {
110 ADD_FAILURE() << "Failed to load enums.xml";
111 return absl::nullopt;
112 }
113
114 absl::optional<HistogramEnumEntryMap> result;
115
116 // Implement simple depth first search.
117 while (true) {
118 const std::string node_name = enums_xml_reader.NodeName();
119 if (node_name == "enum") {
120 std::string name;
121 if (enums_xml_reader.NodeAttribute("name", &name) && name == enum_name) {
122 if (result.has_value()) {
123 ADD_FAILURE() << "Duplicate enum '" << enum_name
124 << "' found in enums.xml";
125 return absl::nullopt;
126 }
127
128 const bool got_into_enum = enums_xml_reader.Read();
129 if (!got_into_enum) {
130 ADD_FAILURE() << "Bad enum '" << enum_name
131 << "' (looks empty) found in enums.xml.";
132 return absl::nullopt;
133 }
134
135 result = ParseEnumFromHistogramsXml(enum_name, &enums_xml_reader);
136 if (!result.has_value()) {
137 ADD_FAILURE() << "Bad enum '" << enum_name
138 << "' found in histograms.xml (format error).";
139 return absl::nullopt;
140 }
141 }
142 }
143 // Go deeper if possible (stops at the closing tag of the deepest node).
144 if (enums_xml_reader.Read())
145 continue;
146
147 // Try next node on the same level (skips closing tag).
148 if (enums_xml_reader.Next())
149 continue;
150
151 // Go up until next node on the same level exists.
152 while (enums_xml_reader.Depth() && !enums_xml_reader.SkipToElement()) {
153 }
154
155 // Reached top. histograms.xml consists of the single top level node
156 // 'histogram-configuration', so this is the end.
157 if (!enums_xml_reader.Depth())
158 break;
159 }
160 return result;
161 }
162
163 } // namespace base
164