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 <optional>
23 #include <ostream>
24 #include <queue>
25 #include <stack>
26 #include <string>
27 #include <vector>
28
29 #include "Resource.h"
30 #include "android-base/macros.h"
31 #include "androidfw/Streams.h"
32 #include "androidfw/StringPiece.h"
33 #include "process/IResourceTableConsumer.h"
34 #include "xml/XmlUtil.h"
35
36 namespace aapt {
37 namespace xml {
38
39 class XmlPullParser : public IPackageDeclStack {
40 public:
41 enum class Event {
42 kBadDocument,
43 kStartDocument,
44 kEndDocument,
45
46 kStartNamespace,
47 kEndNamespace,
48 kStartElement,
49 kEndElement,
50 kText,
51 kComment,
52 kCdataStart,
53 kCdataEnd,
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(android::InputStream* 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 std::optional<ExtractedPackage> TransformPackageAlias(android::StringPiece alias) const override;
122
123 struct PackageDecl {
124 std::string prefix;
125 ExtractedPackage package;
126 };
127
128 const std::vector<PackageDecl>& package_decls() const;
129
130 //
131 // Remaining methods are for retrieving information about attributes
132 // associated with a StartElement.
133 //
134 // Attributes must be in sorted order (according to the less than operator
135 // of struct Attribute).
136 //
137
138 struct Attribute {
139 std::string namespace_uri;
140 std::string name;
141 std::string value;
142
143 int compare(const Attribute& rhs) const;
144 bool operator<(const Attribute& rhs) const;
145 bool operator==(const Attribute& rhs) const;
146 bool operator!=(const Attribute& rhs) const;
147 };
148
149 using const_iterator = std::vector<Attribute>::const_iterator;
150
151 const_iterator begin_attributes() const;
152 const_iterator end_attributes() const;
153 size_t attribute_count() const;
154 const_iterator FindAttribute(android::StringPiece namespace_uri, android::StringPiece name) const;
155
156 private:
157 DISALLOW_COPY_AND_ASSIGN(XmlPullParser);
158
159 static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
160 const char* uri);
161 static void XMLCALL StartElementHandler(void* user_data, const char* name,
162 const char** attrs);
163 static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
164 int len);
165 static void XMLCALL EndElementHandler(void* user_data, const char* name);
166 static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix);
167 static void XMLCALL CommentDataHandler(void* user_data, const char* comment);
168 static void XMLCALL StartCdataSectionHandler(void* user_data);
169 static void XMLCALL EndCdataSectionHandler(void* user_data);
170
171 struct EventData {
172 Event event;
173 size_t line_number;
174 size_t depth;
175 std::string data1;
176 std::string data2;
177 std::vector<Attribute> attributes;
178 };
179
180 android::InputStream* in_;
181 XML_Parser parser_;
182 std::queue<EventData> event_queue_;
183 std::string error_;
184 const std::string empty_;
185 size_t depth_;
186 std::stack<std::string> namespace_uris_;
187 std::vector<PackageDecl> package_aliases_;
188 };
189
190 /**
191 * Finds the attribute in the current element within the global namespace.
192 */
193 std::optional<android::StringPiece> FindAttribute(const XmlPullParser* parser,
194 android::StringPiece name);
195
196 /**
197 * Finds the attribute in the current element within the given namespace.
198 */
199 std::optional<android::StringPiece> FindAttribute(const XmlPullParser* parser,
200 android::StringPiece namespace_uri,
201 android::StringPiece name);
202
203 /**
204 * Finds the attribute in the current element within the global namespace. The
205 * attribute's value
206 * must not be the empty string.
207 */
208 std::optional<android::StringPiece> FindNonEmptyAttribute(const XmlPullParser* parser,
209 android::StringPiece name);
210
211 //
212 // Implementation
213 //
214
215 inline ::std::ostream& operator<<(::std::ostream& out,
216 XmlPullParser::Event event) {
217 switch (event) {
218 case XmlPullParser::Event::kBadDocument:
219 return out << "BadDocument";
220 case XmlPullParser::Event::kStartDocument:
221 return out << "StartDocument";
222 case XmlPullParser::Event::kEndDocument:
223 return out << "EndDocument";
224 case XmlPullParser::Event::kStartNamespace:
225 return out << "StartNamespace";
226 case XmlPullParser::Event::kEndNamespace:
227 return out << "EndNamespace";
228 case XmlPullParser::Event::kStartElement:
229 return out << "StartElement";
230 case XmlPullParser::Event::kEndElement:
231 return out << "EndElement";
232 case XmlPullParser::Event::kText:
233 return out << "Text";
234 case XmlPullParser::Event::kComment:
235 return out << "Comment";
236 case XmlPullParser::Event::kCdataStart:
237 return out << "CdataStart";
238 case XmlPullParser::Event::kCdataEnd:
239 return out << "CdataEnd";
240 }
241 return out;
242 }
243
NextChildNode(XmlPullParser * parser,size_t start_depth)244 inline bool XmlPullParser::NextChildNode(XmlPullParser* parser, size_t start_depth) {
245 Event event;
246
247 // First get back to the start depth.
248 while (IsGoodEvent(event = parser->Next()) && parser->depth() > start_depth + 1) {
249 }
250
251 // Now look for the first good node.
252 while ((event != Event::kEndElement || parser->depth() > start_depth) && IsGoodEvent(event)) {
253 switch (event) {
254 case Event::kText:
255 case Event::kComment:
256 case Event::kStartElement:
257 case Event::kCdataStart:
258 case Event::kCdataEnd:
259 return true;
260 default:
261 break;
262 }
263 event = parser->Next();
264 }
265 return false;
266 }
267
SkipCurrentElement(XmlPullParser * parser)268 inline bool XmlPullParser::SkipCurrentElement(XmlPullParser* parser) {
269 int depth = 1;
270 while (depth > 0) {
271 switch (parser->Next()) {
272 case Event::kEndDocument:
273 return true;
274 case Event::kBadDocument:
275 return false;
276 case Event::kStartElement:
277 depth++;
278 break;
279 case Event::kEndElement:
280 depth--;
281 break;
282 default:
283 break;
284 }
285 }
286 return true;
287 }
288
IsGoodEvent(XmlPullParser::Event event)289 inline bool XmlPullParser::IsGoodEvent(XmlPullParser::Event event) {
290 return event != Event::kBadDocument && event != Event::kEndDocument;
291 }
292
compare(const Attribute & rhs)293 inline int XmlPullParser::Attribute::compare(const Attribute& rhs) const {
294 int cmp = namespace_uri.compare(rhs.namespace_uri);
295 if (cmp != 0) return cmp;
296 return name.compare(rhs.name);
297 }
298
299 inline bool XmlPullParser::Attribute::operator<(const Attribute& rhs) const {
300 return compare(rhs) < 0;
301 }
302
303 inline bool XmlPullParser::Attribute::operator==(const Attribute& rhs) const {
304 return compare(rhs) == 0;
305 }
306
307 inline bool XmlPullParser::Attribute::operator!=(const Attribute& rhs) const {
308 return compare(rhs) != 0;
309 }
310
311 } // namespace xml
312 } // namespace aapt
313
314 #endif // AAPT_XML_PULL_PARSER_H
315