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 "io/Io.h"
35 #include "process/IResourceTableConsumer.h"
36 #include "util/Maybe.h"
37 #include "xml/XmlUtil.h"
38
39 namespace aapt {
40 namespace xml {
41
42 class XmlPullParser : public IPackageDeclStack {
43 public:
44 enum class Event {
45 kBadDocument,
46 kStartDocument,
47 kEndDocument,
48
49 kStartNamespace,
50 kEndNamespace,
51 kStartElement,
52 kEndElement,
53 kText,
54 kComment,
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(io::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 Maybe<ExtractedPackage> TransformPackageAlias(const android::StringPiece& alias) 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 io::InputStream* in_;
173 XML_Parser parser_;
174 std::queue<EventData> event_queue_;
175 std::string error_;
176 const std::string empty_;
177 size_t depth_;
178 std::stack<std::string> namespace_uris_;
179
180 struct PackageDecl {
181 std::string prefix;
182 ExtractedPackage package;
183 };
184 std::vector<PackageDecl> package_aliases_;
185 };
186
187 /**
188 * Finds the attribute in the current element within the global namespace.
189 */
190 Maybe<android::StringPiece> FindAttribute(const XmlPullParser* parser,
191 const android::StringPiece& name);
192
193 /**
194 * Finds the attribute in the current element within the global namespace. The
195 * attribute's value
196 * must not be the empty string.
197 */
198 Maybe<android::StringPiece> FindNonEmptyAttribute(const XmlPullParser* parser,
199 const android::StringPiece& name);
200
201 //
202 // Implementation
203 //
204
205 inline ::std::ostream& operator<<(::std::ostream& out,
206 XmlPullParser::Event event) {
207 switch (event) {
208 case XmlPullParser::Event::kBadDocument:
209 return out << "BadDocument";
210 case XmlPullParser::Event::kStartDocument:
211 return out << "StartDocument";
212 case XmlPullParser::Event::kEndDocument:
213 return out << "EndDocument";
214 case XmlPullParser::Event::kStartNamespace:
215 return out << "StartNamespace";
216 case XmlPullParser::Event::kEndNamespace:
217 return out << "EndNamespace";
218 case XmlPullParser::Event::kStartElement:
219 return out << "StartElement";
220 case XmlPullParser::Event::kEndElement:
221 return out << "EndElement";
222 case XmlPullParser::Event::kText:
223 return out << "Text";
224 case XmlPullParser::Event::kComment:
225 return out << "Comment";
226 }
227 return out;
228 }
229
NextChildNode(XmlPullParser * parser,size_t start_depth)230 inline bool XmlPullParser::NextChildNode(XmlPullParser* parser, size_t start_depth) {
231 Event event;
232
233 // First get back to the start depth.
234 while (IsGoodEvent(event = parser->Next()) && parser->depth() > start_depth + 1) {
235 }
236
237 // Now look for the first good node.
238 while ((event != Event::kEndElement || parser->depth() > start_depth) && IsGoodEvent(event)) {
239 switch (event) {
240 case Event::kText:
241 case Event::kComment:
242 case Event::kStartElement:
243 return true;
244 default:
245 break;
246 }
247 event = parser->Next();
248 }
249 return false;
250 }
251
SkipCurrentElement(XmlPullParser * parser)252 inline bool XmlPullParser::SkipCurrentElement(XmlPullParser* parser) {
253 int depth = 1;
254 while (depth > 0) {
255 switch (parser->Next()) {
256 case Event::kEndDocument:
257 return true;
258 case Event::kBadDocument:
259 return false;
260 case Event::kStartElement:
261 depth++;
262 break;
263 case Event::kEndElement:
264 depth--;
265 break;
266 default:
267 break;
268 }
269 }
270 return true;
271 }
272
IsGoodEvent(XmlPullParser::Event event)273 inline bool XmlPullParser::IsGoodEvent(XmlPullParser::Event event) {
274 return event != Event::kBadDocument && event != Event::kEndDocument;
275 }
276
compare(const Attribute & rhs)277 inline int XmlPullParser::Attribute::compare(const Attribute& rhs) const {
278 int cmp = namespace_uri.compare(rhs.namespace_uri);
279 if (cmp != 0) return cmp;
280 return name.compare(rhs.name);
281 }
282
283 inline bool XmlPullParser::Attribute::operator<(const Attribute& rhs) const {
284 return compare(rhs) < 0;
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
FindAttribute(android::StringPiece namespace_uri,android::StringPiece name)295 inline XmlPullParser::const_iterator XmlPullParser::FindAttribute(
296 android::StringPiece namespace_uri, android::StringPiece name) const {
297 const auto end_iter = end_attributes();
298 const auto iter = std::lower_bound(
299 begin_attributes(), end_iter,
300 std::pair<android::StringPiece, android::StringPiece>(namespace_uri, name),
301 [](const Attribute& attr,
302 const std::pair<android::StringPiece, android::StringPiece>& rhs) -> bool {
303 int cmp = attr.namespace_uri.compare(
304 0, attr.namespace_uri.size(), rhs.first.data(), rhs.first.size());
305 if (cmp < 0) return true;
306 if (cmp > 0) return false;
307 cmp = attr.name.compare(0, attr.name.size(), rhs.second.data(),
308 rhs.second.size());
309 if (cmp < 0) return true;
310 return false;
311 });
312
313 if (iter != end_iter && namespace_uri == iter->namespace_uri &&
314 name == iter->name) {
315 return iter;
316 }
317 return end_iter;
318 }
319
320 } // namespace xml
321 } // namespace aapt
322
323 #endif // AAPT_XML_PULL_PARSER_H
324