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 "Resource.h"
31 #include "android-base/macros.h"
32 #include "androidfw/Streams.h"
33 #include "androidfw/StringPiece.h"
34 #include "process/IResourceTableConsumer.h"
35 #include "xml/XmlUtil.h"
36
37 namespace aapt {
38 namespace xml {
39
40 class XmlPullParser : public IPackageDeclStack {
41 public:
42 enum class Event {
43 kBadDocument,
44 kStartDocument,
45 kEndDocument,
46
47 kStartNamespace,
48 kEndNamespace,
49 kStartElement,
50 kEndElement,
51 kText,
52 kComment,
53 kCdataStart,
54 kCdataEnd,
55 };
56
57 /**
58 * Skips to the next direct descendant node of the given start_depth,
59 * skipping namespace nodes.
60 *
61 * When NextChildNode() returns true, you can expect Comments, Text, and
62 * StartElement events.
63 */
64 static bool NextChildNode(XmlPullParser* parser, size_t start_depth);
65 static bool SkipCurrentElement(XmlPullParser* parser);
66 static bool IsGoodEvent(Event event);
67
68 explicit XmlPullParser(android::InputStream* in);
69 ~XmlPullParser();
70
71 /**
72 * Returns the current event that is being processed.
73 */
74 Event event() const;
75
76 const std::string& error() const;
77
78 /**
79 * Note, unlike XmlPullParser, the first call to next() will return
80 * StartElement of the first element.
81 */
82 Event Next();
83
84 //
85 // These are available for all nodes.
86 //
87
88 const std::string& comment() const;
89 size_t line_number() const;
90 size_t depth() const;
91
92 /**
93 * Returns the character data for a Text event.
94 */
95 const std::string& text() const;
96
97 //
98 // Namespace prefix and URI are available for StartNamespace and EndNamespace.
99 //
100
101 const std::string& namespace_prefix() const;
102 const std::string& namespace_uri() const;
103
104 //
105 // These are available for StartElement and EndElement.
106 //
107
108 const std::string& element_namespace() const;
109 const std::string& element_name() const;
110
111 /*
112 * Uses the current stack of namespaces to resolve the package. Eg:
113 * xmlns:app = "http://schemas.android.com/apk/res/com.android.app"
114 * ...
115 * android:text="@app:string/message"
116 *
117 * In this case, 'app' will be converted to 'com.android.app'.
118 *
119 * If xmlns:app="http://schemas.android.com/apk/res-auto", then
120 * 'package' will be set to 'defaultPackage'.
121 */
122 std::optional<ExtractedPackage> TransformPackageAlias(android::StringPiece alias) const override;
123
124 struct PackageDecl {
125 std::string prefix;
126 ExtractedPackage package;
127 };
128
129 const std::vector<PackageDecl>& package_decls() const;
130
131 //
132 // Remaining methods are for retrieving information about attributes
133 // associated with a StartElement.
134 //
135 // Attributes must be in sorted order (according to the less than operator
136 // of struct Attribute).
137 //
138
139 struct Attribute {
140 std::string namespace_uri;
141 std::string name;
142 std::string value;
143
144 int compare(const Attribute& rhs) const;
145 bool operator<(const Attribute& rhs) const;
146 bool operator==(const Attribute& rhs) const;
147 bool operator!=(const Attribute& rhs) const;
148 };
149
150 using const_iterator = std::vector<Attribute>::const_iterator;
151
152 const_iterator begin_attributes() const;
153 const_iterator end_attributes() const;
154 size_t attribute_count() const;
155 const_iterator FindAttribute(android::StringPiece namespace_uri, android::StringPiece name) const;
156
157 private:
158 DISALLOW_COPY_AND_ASSIGN(XmlPullParser);
159
160 static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
161 const char* uri);
162 static void XMLCALL StartElementHandler(void* user_data, const char* name,
163 const char** attrs);
164 static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
165 int len);
166 static void XMLCALL EndElementHandler(void* user_data, const char* name);
167 static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix);
168 static void XMLCALL CommentDataHandler(void* user_data, const char* comment);
169 static void XMLCALL StartCdataSectionHandler(void* user_data);
170 static void XMLCALL EndCdataSectionHandler(void* user_data);
171
172 struct EventData {
173 Event event;
174 size_t line_number;
175 size_t depth;
176 std::string data1;
177 std::string data2;
178 std::vector<Attribute> attributes;
179 };
180
181 android::InputStream* in_;
182 XML_Parser parser_;
183 std::queue<EventData> event_queue_;
184 std::string error_;
185 const std::string empty_;
186 size_t depth_;
187 std::stack<std::string> namespace_uris_;
188 std::vector<PackageDecl> package_aliases_;
189 };
190
191 /**
192 * Finds the attribute in the current element within the global namespace.
193 */
194 std::optional<android::StringPiece> FindAttribute(const XmlPullParser* parser,
195 android::StringPiece name);
196
197 /**
198 * Finds the attribute in the current element within the global namespace. The
199 * attribute's value
200 * must not be the empty string.
201 */
202 std::optional<android::StringPiece> FindNonEmptyAttribute(const XmlPullParser* parser,
203 android::StringPiece name);
204
205 //
206 // Implementation
207 //
208
209 inline ::std::ostream& operator<<(::std::ostream& out,
210 XmlPullParser::Event event) {
211 switch (event) {
212 case XmlPullParser::Event::kBadDocument:
213 return out << "BadDocument";
214 case XmlPullParser::Event::kStartDocument:
215 return out << "StartDocument";
216 case XmlPullParser::Event::kEndDocument:
217 return out << "EndDocument";
218 case XmlPullParser::Event::kStartNamespace:
219 return out << "StartNamespace";
220 case XmlPullParser::Event::kEndNamespace:
221 return out << "EndNamespace";
222 case XmlPullParser::Event::kStartElement:
223 return out << "StartElement";
224 case XmlPullParser::Event::kEndElement:
225 return out << "EndElement";
226 case XmlPullParser::Event::kText:
227 return out << "Text";
228 case XmlPullParser::Event::kComment:
229 return out << "Comment";
230 case XmlPullParser::Event::kCdataStart:
231 return out << "CdataStart";
232 case XmlPullParser::Event::kCdataEnd:
233 return out << "CdataEnd";
234 }
235 return out;
236 }
237
NextChildNode(XmlPullParser * parser,size_t start_depth)238 inline bool XmlPullParser::NextChildNode(XmlPullParser* parser, size_t start_depth) {
239 Event event;
240
241 // First get back to the start depth.
242 while (IsGoodEvent(event = parser->Next()) && parser->depth() > start_depth + 1) {
243 }
244
245 // Now look for the first good node.
246 while ((event != Event::kEndElement || parser->depth() > start_depth) && IsGoodEvent(event)) {
247 switch (event) {
248 case Event::kText:
249 case Event::kComment:
250 case Event::kStartElement:
251 case Event::kCdataStart:
252 case Event::kCdataEnd:
253 return true;
254 default:
255 break;
256 }
257 event = parser->Next();
258 }
259 return false;
260 }
261
SkipCurrentElement(XmlPullParser * parser)262 inline bool XmlPullParser::SkipCurrentElement(XmlPullParser* parser) {
263 int depth = 1;
264 while (depth > 0) {
265 switch (parser->Next()) {
266 case Event::kEndDocument:
267 return true;
268 case Event::kBadDocument:
269 return false;
270 case Event::kStartElement:
271 depth++;
272 break;
273 case Event::kEndElement:
274 depth--;
275 break;
276 default:
277 break;
278 }
279 }
280 return true;
281 }
282
IsGoodEvent(XmlPullParser::Event event)283 inline bool XmlPullParser::IsGoodEvent(XmlPullParser::Event event) {
284 return event != Event::kBadDocument && event != Event::kEndDocument;
285 }
286
compare(const Attribute & rhs)287 inline int XmlPullParser::Attribute::compare(const Attribute& rhs) const {
288 int cmp = namespace_uri.compare(rhs.namespace_uri);
289 if (cmp != 0) return cmp;
290 return name.compare(rhs.name);
291 }
292
293 inline bool XmlPullParser::Attribute::operator<(const Attribute& rhs) const {
294 return compare(rhs) < 0;
295 }
296
297 inline bool XmlPullParser::Attribute::operator==(const Attribute& rhs) const {
298 return compare(rhs) == 0;
299 }
300
301 inline bool XmlPullParser::Attribute::operator!=(const Attribute& rhs) const {
302 return compare(rhs) != 0;
303 }
304
FindAttribute(android::StringPiece namespace_uri,android::StringPiece name)305 inline XmlPullParser::const_iterator XmlPullParser::FindAttribute(
306 android::StringPiece namespace_uri, android::StringPiece name) const {
307 const auto end_iter = end_attributes();
308 const auto iter = std::lower_bound(
309 begin_attributes(), end_iter,
310 std::pair<android::StringPiece, android::StringPiece>(namespace_uri, name),
311 [](const Attribute& attr,
312 const std::pair<android::StringPiece, android::StringPiece>& rhs) -> bool {
313 int cmp = attr.namespace_uri.compare(
314 0, attr.namespace_uri.size(), rhs.first.data(), rhs.first.size());
315 if (cmp < 0) return true;
316 if (cmp > 0) return false;
317 cmp = attr.name.compare(0, attr.name.size(), rhs.second.data(),
318 rhs.second.size());
319 if (cmp < 0) return true;
320 return false;
321 });
322
323 if (iter != end_iter && namespace_uri == iter->namespace_uri &&
324 name == iter->name) {
325 return iter;
326 }
327 return end_iter;
328 }
329
330 } // namespace xml
331 } // namespace aapt
332
333 #endif // AAPT_XML_PULL_PARSER_H
334