1 /*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef AAPT_XML_PULL_PARSER_H
18 #define AAPT_XML_PULL_PARSER_H
19
20 #include <expat.h>
21
22 #include <algorithm>
23 #include <istream>
24 #include <ostream>
25 #include <queue>
26 #include <stack>
27 #include <string>
28 #include <vector>
29
30 #include "android-base/macros.h"
31 #include "androidfw/StringPiece.h"
32
33 #include "Resource.h"
34 #include "process/IResourceTableConsumer.h"
35 #include "util/Maybe.h"
36 #include "xml/XmlUtil.h"
37
38 namespace aapt {
39 namespace xml {
40
41 class XmlPullParser : public IPackageDeclStack {
42 public:
43 enum class Event {
44 kBadDocument,
45 kStartDocument,
46 kEndDocument,
47
48 kStartNamespace,
49 kEndNamespace,
50 kStartElement,
51 kEndElement,
52 kText,
53 kComment,
54 };
55
56 /**
57 * Skips to the next direct descendant node of the given start_depth,
58 * skipping namespace nodes.
59 *
60 * When NextChildNode() returns true, you can expect Comments, Text, and
61 * StartElement events.
62 */
63 static bool NextChildNode(XmlPullParser* parser, size_t start_depth);
64 static bool SkipCurrentElement(XmlPullParser* parser);
65 static bool IsGoodEvent(Event event);
66
67 explicit XmlPullParser(std::istream& in);
68 ~XmlPullParser();
69
70 /**
71 * Returns the current event that is being processed.
72 */
73 Event event() const;
74
75 const std::string& error() const;
76
77 /**
78 * Note, unlike XmlPullParser, the first call to next() will return
79 * StartElement of the first element.
80 */
81 Event Next();
82
83 //
84 // These are available for all nodes.
85 //
86
87 const std::string& comment() const;
88 size_t line_number() const;
89 size_t depth() const;
90
91 /**
92 * Returns the character data for a Text event.
93 */
94 const std::string& text() const;
95
96 //
97 // Namespace prefix and URI are available for StartNamespace and EndNamespace.
98 //
99
100 const std::string& namespace_prefix() const;
101 const std::string& namespace_uri() const;
102
103 //
104 // These are available for StartElement and EndElement.
105 //
106
107 const std::string& element_namespace() const;
108 const std::string& element_name() const;
109
110 /*
111 * Uses the current stack of namespaces to resolve the package. Eg:
112 * xmlns:app = "http://schemas.android.com/apk/res/com.android.app"
113 * ...
114 * android:text="@app:string/message"
115 *
116 * In this case, 'app' will be converted to 'com.android.app'.
117 *
118 * If xmlns:app="http://schemas.android.com/apk/res-auto", then
119 * 'package' will be set to 'defaultPackage'.
120 */
121 Maybe<ExtractedPackage> TransformPackageAlias(
122 const android::StringPiece& alias, const android::StringPiece& local_package) const override;
123
124 //
125 // Remaining methods are for retrieving information about attributes
126 // associated with a StartElement.
127 //
128 // Attributes must be in sorted order (according to the less than operator
129 // of struct Attribute).
130 //
131
132 struct Attribute {
133 std::string namespace_uri;
134 std::string name;
135 std::string value;
136
137 int compare(const Attribute& rhs) const;
138 bool operator<(const Attribute& rhs) const;
139 bool operator==(const Attribute& rhs) const;
140 bool operator!=(const Attribute& rhs) const;
141 };
142
143 using const_iterator = std::vector<Attribute>::const_iterator;
144
145 const_iterator begin_attributes() const;
146 const_iterator end_attributes() const;
147 size_t attribute_count() const;
148 const_iterator FindAttribute(android::StringPiece namespace_uri, android::StringPiece name) const;
149
150 private:
151 DISALLOW_COPY_AND_ASSIGN(XmlPullParser);
152
153 static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
154 const char* uri);
155 static void XMLCALL StartElementHandler(void* user_data, const char* name,
156 const char** attrs);
157 static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
158 int len);
159 static void XMLCALL EndElementHandler(void* user_data, const char* name);
160 static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix);
161 static void XMLCALL CommentDataHandler(void* user_data, const char* comment);
162
163 struct EventData {
164 Event event;
165 size_t line_number;
166 size_t depth;
167 std::string data1;
168 std::string data2;
169 std::vector<Attribute> attributes;
170 };
171
172 std::istream& in_;
173 XML_Parser parser_;
174 char buffer_[16384];
175 std::queue<EventData> event_queue_;
176 std::string error_;
177 const std::string empty_;
178 size_t depth_;
179 std::stack<std::string> namespace_uris_;
180
181 struct PackageDecl {
182 std::string prefix;
183 ExtractedPackage package;
184 };
185 std::vector<PackageDecl> package_aliases_;
186 };
187
188 /**
189 * Finds the attribute in the current element within the global namespace.
190 */
191 Maybe<android::StringPiece> FindAttribute(const XmlPullParser* parser,
192 const android::StringPiece& name);
193
194 /**
195 * Finds the attribute in the current element within the global namespace. The
196 * attribute's value
197 * must not be the empty string.
198 */
199 Maybe<android::StringPiece> FindNonEmptyAttribute(const XmlPullParser* parser,
200 const android::StringPiece& name);
201
202 //
203 // Implementation
204 //
205
206 inline ::std::ostream& operator<<(::std::ostream& out,
207 XmlPullParser::Event event) {
208 switch (event) {
209 case XmlPullParser::Event::kBadDocument:
210 return out << "BadDocument";
211 case XmlPullParser::Event::kStartDocument:
212 return out << "StartDocument";
213 case XmlPullParser::Event::kEndDocument:
214 return out << "EndDocument";
215 case XmlPullParser::Event::kStartNamespace:
216 return out << "StartNamespace";
217 case XmlPullParser::Event::kEndNamespace:
218 return out << "EndNamespace";
219 case XmlPullParser::Event::kStartElement:
220 return out << "StartElement";
221 case XmlPullParser::Event::kEndElement:
222 return out << "EndElement";
223 case XmlPullParser::Event::kText:
224 return out << "Text";
225 case XmlPullParser::Event::kComment:
226 return out << "Comment";
227 }
228 return out;
229 }
230
NextChildNode(XmlPullParser * parser,size_t start_depth)231 inline bool XmlPullParser::NextChildNode(XmlPullParser* parser,
232 size_t start_depth) {
233 Event event;
234
235 // First get back to the start depth.
236 while (IsGoodEvent(event = parser->Next()) &&
237 parser->depth() > start_depth + 1) {
238 }
239
240 // Now look for the first good node.
241 while ((event != Event::kEndElement || parser->depth() > start_depth) &&
242 IsGoodEvent(event)) {
243 switch (event) {
244 case Event::kText:
245 case Event::kComment:
246 case Event::kStartElement:
247 return true;
248 default:
249 break;
250 }
251 event = parser->Next();
252 }
253 return false;
254 }
255
SkipCurrentElement(XmlPullParser * parser)256 inline bool XmlPullParser::SkipCurrentElement(XmlPullParser* parser) {
257 int depth = 1;
258 while (depth > 0) {
259 switch (parser->Next()) {
260 case Event::kEndDocument:
261 return true;
262 case Event::kBadDocument:
263 return false;
264 case Event::kStartElement:
265 depth++;
266 break;
267 case Event::kEndElement:
268 depth--;
269 break;
270 default:
271 break;
272 }
273 }
274 return true;
275 }
276
IsGoodEvent(XmlPullParser::Event event)277 inline bool XmlPullParser::IsGoodEvent(XmlPullParser::Event event) {
278 return event != Event::kBadDocument && event != Event::kEndDocument;
279 }
280
compare(const Attribute & rhs)281 inline int XmlPullParser::Attribute::compare(const Attribute& rhs) const {
282 int cmp = namespace_uri.compare(rhs.namespace_uri);
283 if (cmp != 0) return cmp;
284 return name.compare(rhs.name);
285 }
286
287 inline bool XmlPullParser::Attribute::operator<(const Attribute& rhs) const {
288 return compare(rhs) < 0;
289 }
290
291 inline bool XmlPullParser::Attribute::operator==(const Attribute& rhs) const {
292 return compare(rhs) == 0;
293 }
294
295 inline bool XmlPullParser::Attribute::operator!=(const Attribute& rhs) const {
296 return compare(rhs) != 0;
297 }
298
FindAttribute(android::StringPiece namespace_uri,android::StringPiece name)299 inline XmlPullParser::const_iterator XmlPullParser::FindAttribute(
300 android::StringPiece namespace_uri, android::StringPiece name) const {
301 const auto end_iter = end_attributes();
302 const auto iter = std::lower_bound(
303 begin_attributes(), end_iter,
304 std::pair<android::StringPiece, android::StringPiece>(namespace_uri, name),
305 [](const Attribute& attr,
306 const std::pair<android::StringPiece, android::StringPiece>& rhs) -> bool {
307 int cmp = attr.namespace_uri.compare(
308 0, attr.namespace_uri.size(), rhs.first.data(), rhs.first.size());
309 if (cmp < 0) return true;
310 if (cmp > 0) return false;
311 cmp = attr.name.compare(0, attr.name.size(), rhs.second.data(),
312 rhs.second.size());
313 if (cmp < 0) return true;
314 return false;
315 });
316
317 if (iter != end_iter && namespace_uri == iter->namespace_uri &&
318 name == iter->name) {
319 return iter;
320 }
321 return end_iter;
322 }
323
324 } // namespace xml
325 } // namespace aapt
326
327 #endif // AAPT_XML_PULL_PARSER_H
328