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 kCdataStart,
56 kCdataEnd,
57 };
58
59 /**
60 * Skips to the next direct descendant node of the given start_depth,
61 * skipping namespace nodes.
62 *
63 * When NextChildNode() returns true, you can expect Comments, Text, and
64 * StartElement events.
65 */
66 static bool NextChildNode(XmlPullParser* parser, size_t start_depth);
67 static bool SkipCurrentElement(XmlPullParser* parser);
68 static bool IsGoodEvent(Event event);
69
70 explicit XmlPullParser(io::InputStream* in);
71 ~XmlPullParser();
72
73 /**
74 * Returns the current event that is being processed.
75 */
76 Event event() const;
77
78 const std::string& error() const;
79
80 /**
81 * Note, unlike XmlPullParser, the first call to next() will return
82 * StartElement of the first element.
83 */
84 Event Next();
85
86 //
87 // These are available for all nodes.
88 //
89
90 const std::string& comment() const;
91 size_t line_number() const;
92 size_t depth() const;
93
94 /**
95 * Returns the character data for a Text event.
96 */
97 const std::string& text() const;
98
99 //
100 // Namespace prefix and URI are available for StartNamespace and EndNamespace.
101 //
102
103 const std::string& namespace_prefix() const;
104 const std::string& namespace_uri() const;
105
106 //
107 // These are available for StartElement and EndElement.
108 //
109
110 const std::string& element_namespace() const;
111 const std::string& element_name() const;
112
113 /*
114 * Uses the current stack of namespaces to resolve the package. Eg:
115 * xmlns:app = "http://schemas.android.com/apk/res/com.android.app"
116 * ...
117 * android:text="@app:string/message"
118 *
119 * In this case, 'app' will be converted to 'com.android.app'.
120 *
121 * If xmlns:app="http://schemas.android.com/apk/res-auto", then
122 * 'package' will be set to 'defaultPackage'.
123 */
124 Maybe<ExtractedPackage> TransformPackageAlias(const android::StringPiece& alias) const override;
125
126 //
127 // Remaining methods are for retrieving information about attributes
128 // associated with a StartElement.
129 //
130 // Attributes must be in sorted order (according to the less than operator
131 // of struct Attribute).
132 //
133
134 struct Attribute {
135 std::string namespace_uri;
136 std::string name;
137 std::string value;
138
139 int compare(const Attribute& rhs) const;
140 bool operator<(const Attribute& rhs) const;
141 bool operator==(const Attribute& rhs) const;
142 bool operator!=(const Attribute& rhs) const;
143 };
144
145 using const_iterator = std::vector<Attribute>::const_iterator;
146
147 const_iterator begin_attributes() const;
148 const_iterator end_attributes() const;
149 size_t attribute_count() const;
150 const_iterator FindAttribute(android::StringPiece namespace_uri, android::StringPiece name) const;
151
152 private:
153 DISALLOW_COPY_AND_ASSIGN(XmlPullParser);
154
155 static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
156 const char* uri);
157 static void XMLCALL StartElementHandler(void* user_data, const char* name,
158 const char** attrs);
159 static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
160 int len);
161 static void XMLCALL EndElementHandler(void* user_data, const char* name);
162 static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix);
163 static void XMLCALL CommentDataHandler(void* user_data, const char* comment);
164 static void XMLCALL StartCdataSectionHandler(void* user_data);
165 static void XMLCALL EndCdataSectionHandler(void* user_data);
166
167 struct EventData {
168 Event event;
169 size_t line_number;
170 size_t depth;
171 std::string data1;
172 std::string data2;
173 std::vector<Attribute> attributes;
174 };
175
176 io::InputStream* in_;
177 XML_Parser parser_;
178 std::queue<EventData> event_queue_;
179 std::string error_;
180 const std::string empty_;
181 size_t depth_;
182 std::stack<std::string> namespace_uris_;
183
184 struct PackageDecl {
185 std::string prefix;
186 ExtractedPackage package;
187 };
188 std::vector<PackageDecl> package_aliases_;
189 };
190
191 /**
192 * Finds the attribute in the current element within the global namespace.
193 */
194 Maybe<android::StringPiece> FindAttribute(const XmlPullParser* parser,
195 const 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 Maybe<android::StringPiece> FindNonEmptyAttribute(const XmlPullParser* parser,
203 const 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