1<?xml version="1.0" encoding="iso-8859-1"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 3 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 4<html> 5<head> 6<!-- 7 __ __ _ 8 ___\ \/ /_ __ __ _| |_ 9 / _ \\ /| '_ \ / _` | __| 10 | __// \| |_) | (_| | |_ 11 \___/_/\_\ .__/ \__,_|\__| 12 |_| XML parser 13 14 Copyright (c) 2000 Clark Cooper <coopercc@users.sourceforge.net> 15 Copyright (c) 2000-2004 Fred L. Drake, Jr. <fdrake@users.sourceforge.net> 16 Copyright (c) 2002-2012 Karl Waclawek <karl@waclawek.net> 17 Copyright (c) 2017-2022 Sebastian Pipping <sebastian@pipping.org> 18 Copyright (c) 2017 Jakub Wilk <jwilk@jwilk.net> 19 Copyright (c) 2021 Tomas Korbar <tkorbar@redhat.com> 20 Copyright (c) 2021 Nicolas Cavallari <nicolas.cavallari@green-communications.fr> 21 Licensed under the MIT license: 22 23 Permission is hereby granted, free of charge, to any person obtaining 24 a copy of this software and associated documentation files (the 25 "Software"), to deal in the Software without restriction, including 26 without limitation the rights to use, copy, modify, merge, publish, 27 distribute, sublicense, and/or sell copies of the Software, and to permit 28 persons to whom the Software is furnished to do so, subject to the 29 following conditions: 30 31 The above copyright notice and this permission notice shall be included 32 in all copies or substantial portions of the Software. 33 34 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 35 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 36 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN 37 NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 38 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 39 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 40 USE OR OTHER DEALINGS IN THE SOFTWARE. 41--> 42 <title>Expat XML Parser</title> 43 <meta name="author" content="Clark Cooper, coopercc@netheaven.com" /> 44 <meta http-equiv="Content-Style-Type" content="text/css" /> 45 <link href="ok.min.css" rel="stylesheet" type="text/css" /> 46 <link href="style.css" rel="stylesheet" type="text/css" /> 47</head> 48<body> 49 <div> 50 <h1> 51 The Expat XML Parser 52 <small>Release 2.4.6</small> 53 </h1> 54 </div> 55<div class="content"> 56 57<p>Expat is a library, written in C, for parsing XML documents. It's 58the underlying XML parser for the open source Mozilla project, Perl's 59<code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and 60other open-source XML parsers.</p> 61 62<p>This library is the creation of James Clark, who's also given us 63groff (an nroff look-alike), Jade (an implementation of ISO's DSSSL 64stylesheet language for SGML), XP (a Java XML parser package), XT (a 65Java XSL engine). James was also the technical lead on the XML 66Working Group at W3C that produced the XML specification.</p> 67 68<p>This is free software, licensed under the <a 69href="../COPYING">MIT/X Consortium license</a>. You may download it 70from <a href="http://www.libexpat.org/">the Expat home page</a>. 71</p> 72 73<p>The bulk of this document was originally commissioned as an article 74by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed 75Clark Cooper to retain copyright and to distribute it with Expat. 76This version has been substantially extended to include documentation 77on features which have been added since the original article was 78published, and additional information on using the original 79interface.</p> 80 81<hr /> 82<h2>Table of Contents</h2> 83<ul> 84 <li><a href="#overview">Overview</a></li> 85 <li><a href="#building">Building and Installing</a></li> 86 <li><a href="#using">Using Expat</a></li> 87 <li><a href="#reference">Reference</a> 88 <ul> 89 <li><a href="#creation">Parser Creation Functions</a> 90 <ul> 91 <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li> 92 <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li> 93 <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li> 94 <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li> 95 <li><a href="#XML_ParserFree">XML_ParserFree</a></li> 96 <li><a href="#XML_ParserReset">XML_ParserReset</a></li> 97 </ul> 98 </li> 99 <li><a href="#parsing">Parsing Functions</a> 100 <ul> 101 <li><a href="#XML_Parse">XML_Parse</a></li> 102 <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li> 103 <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li> 104 <li><a href="#XML_StopParser">XML_StopParser</a></li> 105 <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li> 106 <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li> 107 </ul> 108 </li> 109 <li><a href="#setting">Handler Setting Functions</a> 110 <ul> 111 <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li> 112 <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li> 113 <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li> 114 <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li> 115 <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li> 116 <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li> 117 <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li> 118 <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li> 119 <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li> 120 <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li> 121 <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li> 122 <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li> 123 <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li> 124 <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li> 125 <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li> 126 <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li> 127 <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li> 128 <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li> 129 <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li> 130 <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li> 131 <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li> 132 <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li> 133 <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li> 134 <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li> 135 <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li> 136 <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li> 137 <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li> 138 <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li> 139 </ul> 140 </li> 141 <li><a href="#position">Parse Position and Error Reporting Functions</a> 142 <ul> 143 <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li> 144 <li><a href="#XML_ErrorString">XML_ErrorString</a></li> 145 <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li> 146 <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li> 147 <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li> 148 <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li> 149 <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li> 150 </ul> 151 </li> 152 <li> 153 <a href="#billion-laughs">Billion Laughs Attack Protection</a> 154 <ul> 155 <li><a href="#XML_SetBillionLaughsAttackProtectionMaximumAmplification">XML_SetBillionLaughsAttackProtectionMaximumAmplification</a></li> 156 <li><a href="#XML_SetBillionLaughsAttackProtectionActivationThreshold">XML_SetBillionLaughsAttackProtectionActivationThreshold</a></li> 157 </ul> 158 </li> 159 <li><a href="#miscellaneous">Miscellaneous Functions</a> 160 <ul> 161 <li><a href="#XML_SetUserData">XML_SetUserData</a></li> 162 <li><a href="#XML_GetUserData">XML_GetUserData</a></li> 163 <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li> 164 <li><a href="#XML_SetBase">XML_SetBase</a></li> 165 <li><a href="#XML_GetBase">XML_GetBase</a></li> 166 <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li> 167 <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li> 168 <li><a href="#XML_GetAttributeInfo">XML_GetAttributeInfo</a></li> 169 <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li> 170 <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li> 171 <li><a href="#XML_SetHashSalt">XML_SetHashSalt</a></li> 172 <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li> 173 <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li> 174 <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li> 175 <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li> 176 <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li> 177 <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li> 178 <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li> 179 <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li> 180 <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li> 181 <li><a href="#XML_MemFree">XML_MemFree</a></li> 182 </ul> 183 </li> 184 </ul> 185 </li> 186</ul> 187 188<hr /> 189<h2><a name="overview">Overview</a></h2> 190 191<p>Expat is a stream-oriented parser. You register callback (or 192handler) functions with the parser and then start feeding it the 193document. As the parser recognizes parts of the document, it will 194call the appropriate handler for that part (if you've registered one.) 195The document is fed to the parser in pieces, so you can start parsing 196before you have all the document. This also allows you to parse really 197huge documents that won't fit into memory.</p> 198 199<p>Expat can be intimidating due to the many kinds of handlers and 200options you can set. But you only need to learn four functions in 201order to do 90% of what you'll want to do with it:</p> 202 203<dl> 204 205<dt><code><a href= "#XML_ParserCreate" 206 >XML_ParserCreate</a></code></dt> 207 <dd>Create a new parser object.</dd> 208 209<dt><code><a href= "#XML_SetElementHandler" 210 >XML_SetElementHandler</a></code></dt> 211 <dd>Set handlers for start and end tags.</dd> 212 213<dt><code><a href= "#XML_SetCharacterDataHandler" 214 >XML_SetCharacterDataHandler</a></code></dt> 215 <dd>Set handler for text.</dd> 216 217<dt><code><a href= "#XML_Parse" 218 >XML_Parse</a></code></dt> 219 <dd>Pass a buffer full of document to the parser</dd> 220</dl> 221 222<p>These functions and others are described in the <a 223href="#reference">reference</a> part of this document. The reference 224section also describes in detail the parameters passed to the 225different types of handlers.</p> 226 227<p>Let's look at a very simple example program that only uses 3 of the 228above functions (it doesn't need to set a character handler.) The 229program <a href="../examples/outline.c">outline.c</a> prints an 230element outline, indenting child elements to distinguish them from the 231parent element that contains them. The start handler does all the 232work. It prints two indenting spaces for every level of ancestor 233elements, then it prints the element and attribute 234information. Finally it increments the global <code>Depth</code> 235variable.</p> 236 237<pre class="eg"> 238int Depth; 239 240void XMLCALL 241start(void *data, const char *el, const char **attr) { 242 int i; 243 244 for (i = 0; i < Depth; i++) 245 printf(" "); 246 247 printf("%s", el); 248 249 for (i = 0; attr[i]; i += 2) { 250 printf(" %s='%s'", attr[i], attr[i + 1]); 251 } 252 253 printf("\n"); 254 Depth++; 255} /* End of start handler */ 256</pre> 257 258<p>The end tag simply does the bookkeeping work of decrementing 259<code>Depth</code>.</p> 260<pre class="eg"> 261void XMLCALL 262end(void *data, const char *el) { 263 Depth--; 264} /* End of end handler */ 265</pre> 266 267<p>Note the <code>XMLCALL</code> annotation used for the callbacks. 268This is used to ensure that the Expat and the callbacks are using the 269same calling convention in case the compiler options used for Expat 270itself and the client code are different. Expat tries not to care 271what the default calling convention is, though it may require that it 272be compiled with a default convention of "cdecl" on some platforms. 273For code which uses Expat, however, the calling convention is 274specified by the <code>XMLCALL</code> annotation on most platforms; 275callbacks should be defined using this annotation.</p> 276 277<p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but 278existing working Expat applications don't need to add it (since they 279are already using the "cdecl" calling convention, or they wouldn't be 280working). The annotation is only needed if the default calling 281convention may be something other than "cdecl". To use the annotation 282safely with older versions of Expat, you can conditionally define it 283<em>after</em> including Expat's header file:</p> 284 285<pre class="eg"> 286#include <expat.h> 287 288#ifndef XMLCALL 289#if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) 290#define XMLCALL __cdecl 291#elif defined(__GNUC__) 292#define XMLCALL __attribute__((cdecl)) 293#else 294#define XMLCALL 295#endif 296#endif 297</pre> 298 299<p>After creating the parser, the main program just has the job of 300shoveling the document to the parser so that it can do its work.</p> 301 302<hr /> 303<h2><a name="building">Building and Installing Expat</a></h2> 304 305<p>The Expat distribution comes as a compressed (with GNU gzip) tar 306file. You may download the latest version from <a href= 307"http://sourceforge.net/projects/expat/" >Source Forge</a>. After 308unpacking this, cd into the directory. Then follow either the Win32 309directions or Unix directions below.</p> 310 311<h3>Building under Win32</h3> 312 313<p>If you're using the GNU compiler under cygwin, follow the Unix 314directions in the next section. Otherwise if you have Microsoft's 315Developer Studio installed, 316you can use CMake to generate a <code>.sln</code> file, e.g. 317<code> 318cmake -G"Visual Studio 15 2017" -DCMAKE_BUILD_TYPE=RelWithDebInfo . 319</code>, and build Expat using <code>msbuild /m expat.sln</code> after.</p> 320 321<p>Alternatively, you may download the Win32 binary package that 322contains the "expat.h" include file and a pre-built DLL.</p> 323 324<h3>Building under Unix (or GNU)</h3> 325 326<p>First you'll need to run the configure shell script in order to 327configure the Makefiles and headers for your system.</p> 328 329<p>If you're happy with all the defaults that configure picks for you, 330and you have permission on your system to install into /usr/local, you 331can install Expat with this sequence of commands:</p> 332 333<pre class="eg"> 334./configure 335make 336make install 337</pre> 338 339<p>There are some options that you can provide to this script, but the 340only one we'll mention here is the <code>--prefix</code> option. You 341can find out all the options available by running configure with just 342the <code>--help</code> option.</p> 343 344<p>By default, the configure script sets things up so that the library 345gets installed in <code>/usr/local/lib</code> and the associated 346header file in <code>/usr/local/include</code>. But if you were to 347give the option, <code>--prefix=/home/me/mystuff</code>, then the 348library and header would get installed in 349<code>/home/me/mystuff/lib</code> and 350<code>/home/me/mystuff/include</code> respectively.</p> 351 352<h3>Configuring Expat Using the Pre-Processor</h3> 353 354<p>Expat's feature set can be configured using a small number of 355pre-processor definitions. The definition of this symbols does not 356affect the set of entry points for Expat, only the behavior of the API 357and the definition of character types in the case of 358<code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> 359 360<dl class="cpp-symbols"> 361<dt>XML_DTD</dt> 362<dd>Include support for using and reporting DTD-based content. If 363this is defined, default attribute values from an external DTD subset 364are reported and attribute value normalization occurs based on the 365type of attributes defined in the external subset. Without 366this, Expat has a smaller memory footprint and can be faster, but will 367not load external entities or process conditional sections. This does 368not affect the set of functions available in the API.</dd> 369 370<dt>XML_NS</dt> 371<dd>When defined, support for the <cite><a href= 372"http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> 373specification is included.</dd> 374 375<dt>XML_UNICODE</dt> 376<dd>When defined, character data reported to the application is 377encoded in UTF-16 using wide characters of the type 378<code>XML_Char</code>. This is implied if 379<code>XML_UNICODE_WCHAR_T</code> is defined.</dd> 380 381<dt>XML_UNICODE_WCHAR_T</dt> 382<dd>If defined, causes the <code>XML_Char</code> character type to be 383defined using the <code>wchar_t</code> type; otherwise, <code>unsigned 384short</code> is used. Defining this implies 385<code>XML_UNICODE</code>.</dd> 386 387<dt>XML_LARGE_SIZE</dt> 388<dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> 389integer types to be at least 64 bits in size. This is intended to support 390processing of very large input streams, where the return values of 391<code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, 392<code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and 393<code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> 394could overflow. It may not be supported by all compilers, and is turned 395off by default.</dd> 396 397<dt>XML_CONTEXT_BYTES</dt> 398<dd>The number of input bytes of markup context which the parser will 399ensure are available for reporting via <code><a href= 400"#XML_GetInputContext" >XML_GetInputContext</a></code>. This is 401normally set to 1024, and must be set to a positive integer. If this 402is not defined, the input context will not be available and <code><a 403href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will 404always report NULL. Without this, Expat has a smaller memory 405footprint and can be faster.</dd> 406 407<dt>XML_STATIC</dt> 408<dd>On Windows, this should be set if Expat is going to be linked 409statically with the code that calls it; this is required to get all 410the right MSVC magic annotations correct. This is ignored on other 411platforms.</dd> 412 413<dt>XML_ATTR_INFO</dt> 414<dd>If defined, makes the additional function <code><a href= 415"#XML_GetAttributeInfo" >XML_GetAttributeInfo</a></code> available 416for reporting attribute byte offsets.</dd> 417</dl> 418 419<hr /> 420<h2><a name="using">Using Expat</a></h2> 421 422<h3>Compiling and Linking Against Expat</h3> 423 424<p>Unless you installed Expat in a location not expected by your 425compiler and linker, all you have to do to use Expat in your programs 426is to include the Expat header (<code>#include <expat.h></code>) 427in your files that make calls to it and to tell the linker that it 428needs to link against the Expat library. On Unix systems, this would 429usually be done with the <code>-lexpat</code> argument. Otherwise, 430you'll need to tell the compiler where to look for the Expat header 431and the linker where to find the Expat library. You may also need to 432take steps to tell the operating system where to find this library at 433run time.</p> 434 435<p>On a Unix-based system, here's what a Makefile might look like when 436Expat is installed in a standard location:</p> 437 438<pre class="eg"> 439CC=cc 440LDFLAGS= 441LIBS= -lexpat 442xmlapp: xmlapp.o 443 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 444</pre> 445 446<p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then 447the Makefile would look like this:</p> 448 449<pre class="eg"> 450CC=cc 451CFLAGS= -I/home/me/mystuff/include 452LDFLAGS= 453LIBS= -L/home/me/mystuff/lib -lexpat 454xmlapp: xmlapp.o 455 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 456</pre> 457 458<p>You'd also have to set the environment variable 459<code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or 460to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if 461LD_LIBRARY_PATH already has some directories in it) in order to run 462your application.</p> 463 464<h3>Expat Basics</h3> 465 466<p>As we saw in the example in the overview, the first step in parsing 467an XML document with Expat is to create a parser object. There are <a 468href="#creation">three functions</a> in the Expat API for creating a 469parser object. However, only two of these (<code><a href= 470"#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= 471"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for 472constructing a parser for a top-level document. The object returned 473by these functions is an opaque pointer (i.e. "expat.h" declares it as 474void *) to data with further internal structure. In order to free the 475memory associated with this object you must call <code><a href= 476"#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have 477provided any <a href="#userdata">user data</a> that gets stored in the 478parser, then your application is responsible for freeing it prior to 479calling <code>XML_ParserFree</code>.</p> 480 481<p>The objects returned by the parser creation functions are good for 482parsing only one XML document or external parsed entity. If your 483application needs to parse many XML documents, then it needs to create 484a parser object for each one. The best way to deal with this is to 485create a higher level object that contains all the default 486initialization you want for your parser objects.</p> 487 488<p>Walking through a document hierarchy with a stream oriented parser 489will require a good stack mechanism in order to keep track of current 490context. For instance, to answer the simple question, "What element 491does this text belong to?" requires a stack, since the parser may have 492descended into other elements that are children of the current one and 493has encountered this text on the way out.</p> 494 495<p>The things you're likely to want to keep on a stack are the 496currently opened element and it's attributes. You push this 497information onto the stack in the start handler and you pop it off in 498the end handler.</p> 499 500<p>For some tasks, it is sufficient to just keep information on what 501the depth of the stack is (or would be if you had one.) The outline 502program shown above presents one example. Another such task would be 503skipping over a complete element. When you see the start tag for the 504element you want to skip, you set a skip flag and record the depth at 505which the element started. When the end tag handler encounters the 506same depth, the skipped element has ended and the flag may be 507cleared. If you follow the convention that the root element starts at 5081, then you can use the same variable for skip flag and skip 509depth.</p> 510 511<pre class="eg"> 512void 513init_info(Parseinfo *info) { 514 info->skip = 0; 515 info->depth = 1; 516 /* Other initializations here */ 517} /* End of init_info */ 518 519void XMLCALL 520rawstart(void *data, const char *el, const char **attr) { 521 Parseinfo *inf = (Parseinfo *) data; 522 523 if (! inf->skip) { 524 if (should_skip(inf, el, attr)) { 525 inf->skip = inf->depth; 526 } 527 else 528 start(inf, el, attr); /* This does rest of start handling */ 529 } 530 531 inf->depth++; 532} /* End of rawstart */ 533 534void XMLCALL 535rawend(void *data, const char *el) { 536 Parseinfo *inf = (Parseinfo *) data; 537 538 inf->depth--; 539 540 if (! inf->skip) 541 end(inf, el); /* This does rest of end handling */ 542 543 if (inf->skip == inf->depth) 544 inf->skip = 0; 545} /* End rawend */ 546</pre> 547 548<p>Notice in the above example the difference in how depth is 549manipulated in the start and end handlers. The end tag handler should 550be the mirror image of the start tag handler. This is necessary to 551properly model containment. Since, in the start tag handler, we 552incremented depth <em>after</em> the main body of start tag code, then 553in the end handler, we need to manipulate it <em>before</em> the main 554body. If we'd decided to increment it first thing in the start 555handler, then we'd have had to decrement it last thing in the end 556handler.</p> 557 558<h3 id="userdata">Communicating between handlers</h3> 559 560<p>In order to be able to pass information between different handlers 561without using globals, you'll need to define a data structure to hold 562the shared variables. You can then tell Expat (with the <code><a href= 563"#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a 564pointer to this structure to the handlers. This is the first 565argument received by most handlers. In the <a href="#reference" 566>reference section</a>, an argument to a callback function is named 567<code>userData</code> and have type <code>void *</code> if the user 568data is passed; it will have the type <code>XML_Parser</code> if the 569parser itself is passed. When the parser is passed, the user data may 570be retrieved using <code><a href="#XML_GetUserData" 571>XML_GetUserData</a></code>.</p> 572 573<p>One common case where multiple calls to a single handler may need 574to communicate using an application data structure is the case when 575content passed to the character data handler (set by <code><a href= 576"#XML_SetCharacterDataHandler" 577>XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A 578common first-time mistake with any of the event-oriented interfaces to 579an XML parser is to expect all the text contained in an element to be 580reported by a single call to the character data handler. Expat, like 581many other XML parsers, reports such data as a sequence of calls; 582there's no way to know when the end of the sequence is reached until a 583different callback is made. A buffer referenced by the user data 584structure proves both an effective and convenient place to accumulate 585character data.</p> 586 587<!-- XXX example needed here --> 588 589 590<h3>XML Version</h3> 591 592<p>Expat is an XML 1.0 parser, and as such never complains based on 593the value of the <code>version</code> pseudo-attribute in the XML 594declaration, if present.</p> 595 596<p>If an application needs to check the version number (to support 597alternate processing), it should use the <code><a href= 598"#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to 599set a handler that uses the information in the XML declaration to 600determine what to do. This example shows how to check that only a 601version number of <code>"1.0"</code> is accepted:</p> 602 603<pre class="eg"> 604static int wrong_version; 605static XML_Parser parser; 606 607static void XMLCALL 608xmldecl_handler(void *userData, 609 const XML_Char *version, 610 const XML_Char *encoding, 611 int standalone) 612{ 613 static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; 614 615 int i; 616 617 for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { 618 if (version[i] != Version_1_0[i]) { 619 wrong_version = 1; 620 /* also clear all other handlers: */ 621 XML_SetCharacterDataHandler(parser, NULL); 622 ... 623 return; 624 } 625 } 626 ... 627} 628</pre> 629 630<h3>Namespace Processing</h3> 631 632<p>When the parser is created using the <code><a href= 633"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat 634performs namespace processing. Under namespace processing, Expat 635consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, 636which declare namespaces for the scope of the element in which they 637occur. This means that your start handler will not see these 638attributes. Your application can still be informed of these 639declarations by setting namespace declaration handlers with <a href= 640"#XML_SetNamespaceDeclHandler" 641><code>XML_SetNamespaceDeclHandler</code></a>.</p> 642 643<p>Element type and attribute names that belong to a given namespace 644are passed to the appropriate handler in expanded form. By default 645this expanded form is a concatenation of the namespace URI, the 646separator character (which is the 2nd argument to <code><a href= 647"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local 648name (i.e. the part after the colon). Names with undeclared prefixes 649are not well-formed when namespace processing is enabled, and will 650trigger an error. Unprefixed attribute names are never expanded, 651and unprefixed element names are only expanded when they are in the 652scope of a default namespace.</p> 653 654<p>However if <code><a href= "#XML_SetReturnNSTriplet" 655>XML_SetReturnNSTriplet</a></code> has been called with a non-zero 656<code>do_nst</code> parameter, then the expanded form for names with 657an explicit prefix is a concatenation of: URI, separator, local name, 658separator, prefix.</p> 659 660<p>You can set handlers for the start of a namespace declaration and 661for the end of a scope of a declaration with the <code><a href= 662"#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> 663function. The StartNamespaceDeclHandler is called prior to the start 664tag handler and the EndNamespaceDeclHandler is called after the 665corresponding end tag that ends the namespace's scope. The namespace 666start handler gets passed the prefix and URI for the namespace. For a 667default namespace declaration (xmlns='...'), the prefix will be null. 668The URI will be null for the case where the default namespace is being 669unset. The namespace end handler just gets the prefix for the closing 670scope.</p> 671 672<p>These handlers are called for each declaration. So if, for 673instance, a start tag had three namespace declarations, then the 674StartNamespaceDeclHandler would be called three times before the start 675tag handler is called, once for each declaration.</p> 676 677<h3>Character Encodings</h3> 678 679<p>While XML is based on Unicode, and every XML processor is required 680to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), 681other encodings may be declared in XML documents or entities. For the 682main document, an XML declaration may contain an encoding 683declaration:</p> 684<pre> 685<?xml version="1.0" encoding="ISO-8859-2"?> 686</pre> 687 688<p>External parsed entities may begin with a text declaration, which 689looks like an XML declaration with just an encoding declaration:</p> 690<pre> 691<?xml encoding="Big5"?> 692</pre> 693 694<p>With Expat, you may also specify an encoding at the time of 695creating a parser. This is useful when the encoding information may 696come from a source outside the document itself (like a higher level 697protocol.)</p> 698 699<p><a name="builtin_encodings"></a>There are four built-in encodings 700in Expat:</p> 701<ul> 702<li>UTF-8</li> 703<li>UTF-16</li> 704<li>ISO-8859-1</li> 705<li>US-ASCII</li> 706</ul> 707 708<p>Anything else discovered in an encoding declaration or in the 709protocol encoding specified in the parser constructor, triggers a call 710to the <code>UnknownEncodingHandler</code>. This handler gets passed 711the encoding name and a pointer to an <code>XML_Encoding</code> data 712structure. Your handler must fill in this structure and return 713<code>XML_STATUS_OK</code> if it knows how to deal with the 714encoding. Otherwise the handler should return 715<code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer 716to an optional application data structure that you may indicate when 717you set the handler.</p> 718 719<p>Expat places restrictions on character encodings that it can 720support by filling in the <code>XML_Encoding</code> structure. 721include file:</p> 722<ol> 723<li>Every ASCII character that can appear in a well-formed XML document 724must be represented by a single byte, and that byte must correspond to 725it's ASCII encoding (except for the characters $@\^'{}~)</li> 726<li>Characters must be encoded in 4 bytes or less.</li> 727<li>All characters encoded must have Unicode scalar values less than or 728equal to 65535 (0xFFFF)<em>This does not apply to the built-in support 729for UTF-16 and UTF-8</em></li> 730<li>No character may be encoded by more that one distinct sequence of 731bytes</li> 732</ol> 733 734<p><code>XML_Encoding</code> contains an array of integers that 735correspond to the 1st byte of an encoding sequence. If the value in 736the array for a byte is zero or positive, then the byte is a single 737byte encoding that encodes the Unicode scalar value contained in the 738array. A -1 in this array indicates a malformed byte. If the value is 739-2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte 740sequence respectively. Multi-byte sequences are sent to the convert 741function pointed at in the <code>XML_Encoding</code> structure. This 742function should return the Unicode scalar value for the sequence or -1 743if the sequence is malformed.</p> 744 745<p>One pitfall that novice Expat users are likely to fall into is that 746although Expat may accept input in various encodings, the strings that 747it passes to the handlers are always encoded in UTF-8 or UTF-16 748(depending on how Expat was compiled). Your application is responsible 749for any translation of these strings into other encodings.</p> 750 751<h3>Handling External Entity References</h3> 752 753<p>Expat does not read or parse external entities directly. Note that 754any external DTD is a special case of an external entity. If you've 755set no <code>ExternalEntityRefHandler</code>, then external entity 756references are silently ignored. Otherwise, it calls your handler with 757the information needed to read and parse the external entity.</p> 758 759<p>Your handler isn't actually responsible for parsing the entity, but 760it is responsible for creating a subsidiary parser with <code><a href= 761"#XML_ExternalEntityParserCreate" 762>XML_ExternalEntityParserCreate</a></code> that will do the job. This 763returns an instance of <code>XML_Parser</code> that has handlers and 764other data structures initialized from the parent parser. You may then 765use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a 766href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this 767parser. Since external entities my refer to other external entities, 768your handler should be prepared to be called recursively.</p> 769 770<h3>Parsing DTDs</h3> 771 772<p>In order to parse parameter entities, before starting the parse, 773you must call <code><a href= "#XML_SetParamEntityParsing" 774>XML_SetParamEntityParsing</a></code> with one of the following 775arguments:</p> 776<dl> 777<dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> 778<dd>Don't parse parameter entities or the external subset</dd> 779<dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> 780<dd>Parse parameter entities and the external subset unless 781<code>standalone</code> was set to "yes" in the XML declaration.</dd> 782<dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> 783<dd>Always parse parameter entities and the external subset</dd> 784</dl> 785 786<p>In order to read an external DTD, you also have to set an external 787entity reference handler as described above.</p> 788 789<h3 id="stop-resume">Temporarily Stopping Parsing</h3> 790 791<p>Expat 1.95.8 introduces a new feature: its now possible to stop 792parsing temporarily from within a handler function, even if more data 793has already been passed into the parser. Applications for this 794include</p> 795 796<ul> 797 <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" 798 >XInclude</a> specification.</li> 799 800 <li>Delaying further processing until additional information is 801 available from some other source.</li> 802 803 <li>Adjusting processor load as task priorities shift within an 804 application.</li> 805 806 <li>Stopping parsing completely (simply free or reset the parser 807 instead of resuming in the outer parsing loop). This can be useful 808 if an application-domain error is found in the XML being parsed or if 809 the result of the parse is determined not to be useful after 810 all.</li> 811</ul> 812 813<p>To take advantage of this feature, the main parsing loop of an 814application needs to support this specifically. It cannot be 815supported with a parsing loop compatible with Expat 1.95.7 or 816earlier (though existing loops will continue to work without 817supporting the stop/resume feature).</p> 818 819<p>An application that uses this feature for a single parser will have 820the rough structure (in pseudo-code):</p> 821 822<pre class="pseudocode"> 823fd = open_input() 824p = create_parser() 825 826if parse_xml(p, fd) { 827 /* suspended */ 828 829 int suspended = 1; 830 831 while (suspended) { 832 do_something_else() 833 if ready_to_resume() { 834 suspended = continue_parsing(p, fd); 835 } 836 } 837} 838</pre> 839 840<p>An application that may resume any of several parsers based on 841input (either from the XML being parsed or some other source) will 842certainly have more interesting control structures.</p> 843 844<p>This C function could be used for the <code>parse_xml</code> 845function mentioned in the pseudo-code above:</p> 846 847<pre class="eg"> 848#define BUFF_SIZE 10240 849 850/* Parse a document from the open file descriptor 'fd' until the parse 851 is complete (the document has been completely parsed, or there's 852 been an error), or the parse is stopped. Return non-zero when 853 the parse is merely suspended. 854*/ 855int 856parse_xml(XML_Parser p, int fd) 857{ 858 for (;;) { 859 int last_chunk; 860 int bytes_read; 861 enum XML_Status status; 862 863 void *buff = XML_GetBuffer(p, BUFF_SIZE); 864 if (buff == NULL) { 865 /* handle error... */ 866 return 0; 867 } 868 bytes_read = read(fd, buff, BUFF_SIZE); 869 if (bytes_read < 0) { 870 /* handle error... */ 871 return 0; 872 } 873 status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); 874 switch (status) { 875 case XML_STATUS_ERROR: 876 /* handle error... */ 877 return 0; 878 case XML_STATUS_SUSPENDED: 879 return 1; 880 } 881 if (bytes_read == 0) 882 return 0; 883 } 884} 885</pre> 886 887<p>The corresponding <code>continue_parsing</code> function is 888somewhat simpler, since it only need deal with the return code from 889<code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can 890delegate the input handling to the <code>parse_xml</code> 891function:</p> 892 893<pre class="eg"> 894/* Continue parsing a document which had been suspended. The 'p' and 895 'fd' arguments are the same as passed to parse_xml(). Return 896 non-zero when the parse is suspended. 897*/ 898int 899continue_parsing(XML_Parser p, int fd) 900{ 901 enum XML_Status status = XML_ResumeParser(p); 902 switch (status) { 903 case XML_STATUS_ERROR: 904 /* handle error... */ 905 return 0; 906 case XML_ERROR_NOT_SUSPENDED: 907 /* handle error... */ 908 return 0;. 909 case XML_STATUS_SUSPENDED: 910 return 1; 911 } 912 return parse_xml(p, fd); 913} 914</pre> 915 916<p>Now that we've seen what a mess the top-level parsing loop can 917become, what have we gained? Very simply, we can now use the <code><a 918href= "#XML_StopParser" >XML_StopParser</a></code> function to stop 919parsing, without having to go to great lengths to avoid additional 920processing that we're expecting to ignore. As a bonus, we get to stop 921parsing <em>temporarily</em>, and come back to it when we're 922ready.</p> 923 924<p>To stop parsing from a handler function, use the <code><a href= 925"#XML_StopParser" >XML_StopParser</a></code> function. This function 926takes two arguments; the parser being stopped and a flag indicating 927whether the parse can be resumed in the future.</p> 928 929<!-- XXX really need more here --> 930 931 932<hr /> 933<!-- ================================================================ --> 934 935<h2><a name="reference">Expat Reference</a></h2> 936 937<h3><a name="creation">Parser Creation</a></h3> 938 939<h4 id="XML_ParserCreate">XML_ParserCreate</h4> 940<pre class="fcndec"> 941XML_Parser XMLCALL 942XML_ParserCreate(const XML_Char *encoding); 943</pre> 944<div class="fcndef"> 945Construct a new parser. If encoding is non-null, it specifies a 946character encoding to use for the document. This overrides the document 947encoding declaration. There are four built-in encodings: 948<ul> 949<li>US-ASCII</li> 950<li>UTF-8</li> 951<li>UTF-16</li> 952<li>ISO-8859-1</li> 953</ul> 954Any other value will invoke a call to the UnknownEncodingHandler. 955</div> 956 957<h4 id="XML_ParserCreateNS">XML_ParserCreateNS</h4> 958<pre class="fcndec"> 959XML_Parser XMLCALL 960XML_ParserCreateNS(const XML_Char *encoding, 961 XML_Char sep); 962</pre> 963<div class="fcndef"> 964Constructs a new parser that has namespace processing in effect. Namespace 965expanded element names and attribute names are returned as a concatenation 966of the namespace URI, <em>sep</em>, and the local part of the name. This 967means that you should pick a character for <em>sep</em> that can't be part 968of an URI. Since Expat does not check namespace URIs for conformance, the 969only safe choice for a namespace separator is a character that is illegal 970in XML. For instance, <code>'\xFF'</code> is not legal in UTF-8, and 971<code>'\xFFFF'</code> is not legal in UTF-16. There is a special case when 972<em>sep</em> is the null character <code>'\0'</code>: the namespace URI and 973the local part will be concatenated without any separator - this is intended 974to support RDF processors. It is a programming error to use the null separator 975with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> 976 977<h4 id="XML_ParserCreate_MM">XML_ParserCreate_MM</h4> 978<pre class="fcndec"> 979XML_Parser XMLCALL 980XML_ParserCreate_MM(const XML_Char *encoding, 981 const XML_Memory_Handling_Suite *ms, 982 const XML_Char *sep); 983</pre> 984<pre class="signature"> 985typedef struct { 986 void *(XMLCALL *malloc_fcn)(size_t size); 987 void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); 988 void (XMLCALL *free_fcn)(void *ptr); 989} XML_Memory_Handling_Suite; 990</pre> 991<div class="fcndef"> 992<p>Construct a new parser using the suite of memory handling functions 993specified in <code>ms</code>. If <code>ms</code> is NULL, then use the 994standard set of memory management functions. If <code>sep</code> is 995non NULL, then namespace processing is enabled in the created parser 996and the character pointed at by sep is used as the separator between 997the namespace URI and the local part of the name.</p> 998</div> 999 1000<h4 id="XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</h4> 1001<pre class="fcndec"> 1002XML_Parser XMLCALL 1003XML_ExternalEntityParserCreate(XML_Parser p, 1004 const XML_Char *context, 1005 const XML_Char *encoding); 1006</pre> 1007<div class="fcndef"> 1008Construct a new <code>XML_Parser</code> object for parsing an external 1009general entity. Context is the context argument passed in a call to a 1010ExternalEntityRefHandler. Other state information such as handlers, 1011user data, namespace processing is inherited from the parser passed as 1012the 1st argument. So you shouldn't need to call any of the behavior 1013changing functions on this parser (unless you want it to act 1014differently than the parent parser). 1015</div> 1016 1017<h4 id="XML_ParserFree">XML_ParserFree</h4> 1018<pre class="fcndec"> 1019void XMLCALL 1020XML_ParserFree(XML_Parser p); 1021</pre> 1022<div class="fcndef"> 1023Free memory used by the parser. Your application is responsible for 1024freeing any memory associated with <a href="#userdata">user data</a>. 1025</div> 1026 1027<h4 id="XML_ParserReset">XML_ParserReset</h4> 1028<pre class="fcndec"> 1029XML_Bool XMLCALL 1030XML_ParserReset(XML_Parser p, 1031 const XML_Char *encoding); 1032</pre> 1033<div class="fcndef"> 1034Clean up the memory structures maintained by the parser so that it may 1035be used again. After this has been called, <code>parser</code> is 1036ready to start parsing a new document. All handlers are cleared from 1037the parser, except for the unknownEncodingHandler. The parser's external 1038state is re-initialized except for the values of ns and ns_triplets. 1039This function may not be used on a parser created using <code><a href= 1040"#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a 1041></code>; it will return <code>XML_FALSE</code> in that case. Returns 1042<code>XML_TRUE</code> on success. Your application is responsible for 1043dealing with any memory associated with <a href="#userdata">user data</a>. 1044</div> 1045 1046<h3><a name="parsing">Parsing</a></h3> 1047 1048<p>To state the obvious: the three parsing functions <code><a href= 1049"#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> 1050XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> 1051XML_GetBuffer</a></code> must not be called from within a handler 1052unless they operate on a separate parser instance, that is, one that 1053did not call the handler. For example, it is OK to call the parsing 1054functions from within an <code>XML_ExternalEntityRefHandler</code>, 1055if they apply to the parser created by 1056<code><a href= "#XML_ExternalEntityParserCreate" 1057>XML_ExternalEntityParserCreate</a></code>.</p> 1058 1059<p>Note: The <code>len</code> argument passed to these functions 1060should be considerably less than the maximum value for an integer, 1061as it could create an integer overflow situation if the added 1062lengths of a buffer and the unprocessed portion of the previous buffer 1063exceed the maximum integer value. Input data at the end of a buffer 1064will remain unprocessed if it is part of an XML token for which the 1065end is not part of that buffer.</p> 1066 1067<h4 id="XML_Parse">XML_Parse</h4> 1068<pre class="fcndec"> 1069enum XML_Status XMLCALL 1070XML_Parse(XML_Parser p, 1071 const char *s, 1072 int len, 1073 int isFinal); 1074</pre> 1075<pre class="signature"> 1076enum XML_Status { 1077 XML_STATUS_ERROR = 0, 1078 XML_STATUS_OK = 1 1079}; 1080</pre> 1081<div class="fcndef"> 1082Parse some more of the document. The string <code>s</code> is a buffer 1083containing part (or perhaps all) of the document. The number of bytes of s 1084that are part of the document is indicated by <code>len</code>. This means 1085that <code>s</code> doesn't have to be null terminated. It also means that 1086if <code>len</code> is larger than the number of bytes in the block of 1087memory that <code>s</code> points at, then a memory fault is likely. The 1088<code>isFinal</code> parameter informs the parser that this is the last 1089piece of the document. Frequently, the last piece is empty (i.e. 1090<code>len</code> is zero.) 1091If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. 1092Otherwise it returns <code>XML_STATUS_OK</code> value. 1093</div> 1094 1095<h4 id="XML_ParseBuffer">XML_ParseBuffer</h4> 1096<pre class="fcndec"> 1097enum XML_Status XMLCALL 1098XML_ParseBuffer(XML_Parser p, 1099 int len, 1100 int isFinal); 1101</pre> 1102<div class="fcndef"> 1103This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, 1104except in this case Expat provides the buffer. By obtaining the 1105buffer from Expat with the <code><a href= "#XML_GetBuffer" 1106>XML_GetBuffer</a></code> function, the application can avoid double 1107copying of the input. 1108</div> 1109 1110<h4 id="XML_GetBuffer">XML_GetBuffer</h4> 1111<pre class="fcndec"> 1112void * XMLCALL 1113XML_GetBuffer(XML_Parser p, 1114 int len); 1115</pre> 1116<div class="fcndef"> 1117Obtain a buffer of size <code>len</code> to read a piece of the document 1118into. A NULL value is returned if Expat can't allocate enough memory for 1119this buffer. A NULL value may also be returned if <code>len</code> is zero. 1120This has to be called prior to every call to 1121<code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A 1122typical use would look like this: 1123 1124<pre class="eg"> 1125for (;;) { 1126 int bytes_read; 1127 void *buff = XML_GetBuffer(p, BUFF_SIZE); 1128 if (buff == NULL) { 1129 /* handle error */ 1130 } 1131 1132 bytes_read = read(docfd, buff, BUFF_SIZE); 1133 if (bytes_read < 0) { 1134 /* handle error */ 1135 } 1136 1137 if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { 1138 /* handle parse error */ 1139 } 1140 1141 if (bytes_read == 0) 1142 break; 1143} 1144</pre> 1145</div> 1146 1147<h4 id="XML_StopParser">XML_StopParser</h4> 1148<pre class="fcndec"> 1149enum XML_Status XMLCALL 1150XML_StopParser(XML_Parser p, 1151 XML_Bool resumable); 1152</pre> 1153<div class="fcndef"> 1154 1155<p>Stops parsing, causing <code><a href= "#XML_Parse" 1156>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 1157>XML_ParseBuffer</a></code> to return. Must be called from within a 1158call-back handler, except when aborting (when <code>resumable</code> 1159is <code>XML_FALSE</code>) an already suspended parser. Some 1160call-backs may still follow because they would otherwise get 1161lost, including</p> 1162<ul> 1163 <li> the end element handler for empty elements when stopped in the 1164 start element handler,</li> 1165 <li> the end namespace declaration handler when stopped in the end 1166 element handler,</li> 1167 <li> the character data handler when stopped in the character data handler 1168 while making multiple call-backs on a contiguous chunk of characters,</li> 1169</ul> 1170<p>and possibly others.</p> 1171 1172<p>This can be called from most handlers, including DTD related 1173call-backs, except when parsing an external parameter entity and 1174<code>resumable</code> is <code>XML_TRUE</code>. Returns 1175<code>XML_STATUS_OK</code> when successful, 1176<code>XML_STATUS_ERROR</code> otherwise. The possible error codes 1177are:</p> 1178<dl> 1179 <dt><code>XML_ERROR_SUSPENDED</code></dt> 1180 <dd>when suspending an already suspended parser.</dd> 1181 <dt><code>XML_ERROR_FINISHED</code></dt> 1182 <dd>when the parser has already finished.</dd> 1183 <dt><code>XML_ERROR_SUSPEND_PE</code></dt> 1184 <dd>when suspending while parsing an external PE.</dd> 1185</dl> 1186 1187<p>Since the stop/resume feature requires application support in the 1188outer parsing loop, it is an error to call this function for a parser 1189not being handled appropriately; see <a href= "#stop-resume" 1190>Temporarily Stopping Parsing</a> for more information.</p> 1191 1192<p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing 1193is <em>suspended</em>, that is, <code><a href= "#XML_Parse" 1194>XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" 1195>XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. 1196Otherwise, parsing is <em>aborted</em>, that is, <code><a href= 1197"#XML_Parse" >XML_Parse</a></code> and <code><a href= 1198"#XML_ParseBuffer" >XML_ParseBuffer</a></code> return 1199<code>XML_STATUS_ERROR</code> with error code 1200<code>XML_ERROR_ABORTED</code>.</p> 1201 1202<p><strong>Note:</strong> 1203This will be applied to the current parser instance only, that is, if 1204there is a parent parser then it will continue parsing when the 1205external entity reference handler returns. It is up to the 1206implementation of that handler to call <code><a href= 1207"#XML_StopParser" >XML_StopParser</a></code> on the parent parser 1208(recursively), if one wants to stop parsing altogether.</p> 1209 1210<p>When suspended, parsing can be resumed by calling <code><a href= 1211"#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> 1212 1213<p>New in Expat 1.95.8.</p> 1214</div> 1215 1216<h4 id="XML_ResumeParser">XML_ResumeParser</h4> 1217<pre class="fcndec"> 1218enum XML_Status XMLCALL 1219XML_ResumeParser(XML_Parser p); 1220</pre> 1221<div class="fcndef"> 1222<p>Resumes parsing after it has been suspended with <code><a href= 1223"#XML_StopParser" >XML_StopParser</a></code>. Must not be called from 1224within a handler call-back. Returns same status codes as <code><a 1225href= "#XML_Parse">XML_Parse</a></code> or <code><a href= 1226"#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error 1227code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the 1228parser was not currently suspended.</p> 1229 1230<p><strong>Note:</strong> 1231This must be called on the most deeply nested child parser instance 1232first, and on its parent parser only after the child parser has 1233finished, to be applied recursively until the document entity's parser 1234is restarted. That is, the parent parser will not resume by itself 1235and it is up to the application to call <code><a href= 1236"#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the 1237appropriate moment.</p> 1238 1239<p>New in Expat 1.95.8.</p> 1240</div> 1241 1242<h4 id="XML_GetParsingStatus">XML_GetParsingStatus</h4> 1243<pre class="fcndec"> 1244void XMLCALL 1245XML_GetParsingStatus(XML_Parser p, 1246 XML_ParsingStatus *status); 1247</pre> 1248<pre class="signature"> 1249enum XML_Parsing { 1250 XML_INITIALIZED, 1251 XML_PARSING, 1252 XML_FINISHED, 1253 XML_SUSPENDED 1254}; 1255 1256typedef struct { 1257 enum XML_Parsing parsing; 1258 XML_Bool finalBuffer; 1259} XML_ParsingStatus; 1260</pre> 1261<div class="fcndef"> 1262<p>Returns status of parser with respect to being initialized, 1263parsing, finished, or suspended, and whether the final buffer is being 1264processed. The <code>status</code> parameter <em>must not</em> be 1265NULL.</p> 1266 1267<p>New in Expat 1.95.8.</p> 1268</div> 1269 1270 1271<h3><a name="setting">Handler Setting</a></h3> 1272 1273<p>Although handlers are typically set prior to parsing and left alone, an 1274application may choose to set or change the handler for a parsing event 1275while the parse is in progress. For instance, your application may choose 1276to ignore all text not descended from a <code>para</code> element. One 1277way it could do this is to set the character handler when a para start tag 1278is seen, and unset it for the corresponding end tag.</p> 1279 1280<p>A handler may be <em>unset</em> by providing a NULL pointer to the 1281appropriate handler setter. None of the handler setting functions have 1282a return value.</p> 1283 1284<p>Your handlers will be receiving strings in arrays of type 1285<code>XML_Char</code>. This type is conditionally defined in expat.h as 1286either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. 1287The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. 1288Note that you'll receive them in this form independent of the original 1289encoding of the document.</p> 1290 1291<div class="handler"> 1292<h4 id="XML_SetStartElementHandler">XML_SetStartElementHandler</h4> 1293<pre class="setter"> 1294void XMLCALL 1295XML_SetStartElementHandler(XML_Parser p, 1296 XML_StartElementHandler start); 1297</pre> 1298<pre class="signature"> 1299typedef void 1300(XMLCALL *XML_StartElementHandler)(void *userData, 1301 const XML_Char *name, 1302 const XML_Char **atts); 1303</pre> 1304<p>Set handler for start (and empty) tags. Attributes are passed to the start 1305handler as a pointer to a vector of char pointers. Each attribute seen in 1306a start (or empty) tag occupies 2 consecutive places in this vector: the 1307attribute name followed by the attribute value. These pairs are terminated 1308by a null pointer.</p> 1309<p>Note that an empty tag generates a call to both start and end handlers 1310(in that order).</p> 1311</div> 1312 1313<div class="handler"> 1314<h4 id="XML_SetEndElementHandler">XML_SetEndElementHandler</h4> 1315<pre class="setter"> 1316void XMLCALL 1317XML_SetEndElementHandler(XML_Parser p, 1318 XML_EndElementHandler); 1319</pre> 1320<pre class="signature"> 1321typedef void 1322(XMLCALL *XML_EndElementHandler)(void *userData, 1323 const XML_Char *name); 1324</pre> 1325<p>Set handler for end (and empty) tags. As noted above, an empty tag 1326generates a call to both start and end handlers.</p> 1327</div> 1328 1329<div class="handler"> 1330<h4 id="XML_SetElementHandler">XML_SetElementHandler</h4> 1331<pre class="setter"> 1332void XMLCALL 1333XML_SetElementHandler(XML_Parser p, 1334 XML_StartElementHandler start, 1335 XML_EndElementHandler end); 1336</pre> 1337<p>Set handlers for start and end tags with one call.</p> 1338</div> 1339 1340<div class="handler"> 1341<h4 id="XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</h4> 1342<pre class="setter"> 1343void XMLCALL 1344XML_SetCharacterDataHandler(XML_Parser p, 1345 XML_CharacterDataHandler charhndl) 1346</pre> 1347<pre class="signature"> 1348typedef void 1349(XMLCALL *XML_CharacterDataHandler)(void *userData, 1350 const XML_Char *s, 1351 int len); 1352</pre> 1353<p>Set a text handler. The string your handler receives 1354is <em>NOT null-terminated</em>. You have to use the length argument 1355to deal with the end of the string. A single block of contiguous text 1356free of markup may still result in a sequence of calls to this handler. 1357In other words, if you're searching for a pattern in the text, it may 1358be split across calls to this handler. Note: Setting this handler to NULL 1359may <em>NOT immediately</em> terminate call-backs if the parser is currently 1360processing such a single block of contiguous markup-free text, as the parser 1361will continue calling back until the end of the block is reached.</p> 1362</div> 1363 1364<div class="handler"> 1365<h4 id="XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</h4> 1366<pre class="setter"> 1367void XMLCALL 1368XML_SetProcessingInstructionHandler(XML_Parser p, 1369 XML_ProcessingInstructionHandler proc) 1370</pre> 1371<pre class="signature"> 1372typedef void 1373(XMLCALL *XML_ProcessingInstructionHandler)(void *userData, 1374 const XML_Char *target, 1375 const XML_Char *data); 1376 1377</pre> 1378<p>Set a handler for processing instructions. The target is the first word 1379in the processing instruction. The data is the rest of the characters in 1380it after skipping all whitespace after the initial word.</p> 1381</div> 1382 1383<div class="handler"> 1384<h4 id="XML_SetCommentHandler">XML_SetCommentHandler</h4> 1385<pre class="setter"> 1386void XMLCALL 1387XML_SetCommentHandler(XML_Parser p, 1388 XML_CommentHandler cmnt) 1389</pre> 1390<pre class="signature"> 1391typedef void 1392(XMLCALL *XML_CommentHandler)(void *userData, 1393 const XML_Char *data); 1394</pre> 1395<p>Set a handler for comments. The data is all text inside the comment 1396delimiters.</p> 1397</div> 1398 1399<div class="handler"> 1400<h4 id="XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</h4> 1401<pre class="setter"> 1402void XMLCALL 1403XML_SetStartCdataSectionHandler(XML_Parser p, 1404 XML_StartCdataSectionHandler start); 1405</pre> 1406<pre class="signature"> 1407typedef void 1408(XMLCALL *XML_StartCdataSectionHandler)(void *userData); 1409</pre> 1410<p>Set a handler that gets called at the beginning of a CDATA section.</p> 1411</div> 1412 1413<div class="handler"> 1414<h4 id="XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</h4> 1415<pre class="setter"> 1416void XMLCALL 1417XML_SetEndCdataSectionHandler(XML_Parser p, 1418 XML_EndCdataSectionHandler end); 1419</pre> 1420<pre class="signature"> 1421typedef void 1422(XMLCALL *XML_EndCdataSectionHandler)(void *userData); 1423</pre> 1424<p>Set a handler that gets called at the end of a CDATA section.</p> 1425</div> 1426 1427<div class="handler"> 1428<h4 id="XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</h4> 1429<pre class="setter"> 1430void XMLCALL 1431XML_SetCdataSectionHandler(XML_Parser p, 1432 XML_StartCdataSectionHandler start, 1433 XML_EndCdataSectionHandler end) 1434</pre> 1435<p>Sets both CDATA section handlers with one call.</p> 1436</div> 1437 1438<div class="handler"> 1439<h4 id="XML_SetDefaultHandler">XML_SetDefaultHandler</h4> 1440<pre class="setter"> 1441void XMLCALL 1442XML_SetDefaultHandler(XML_Parser p, 1443 XML_DefaultHandler hndl) 1444</pre> 1445<pre class="signature"> 1446typedef void 1447(XMLCALL *XML_DefaultHandler)(void *userData, 1448 const XML_Char *s, 1449 int len); 1450</pre> 1451 1452<p>Sets a handler for any characters in the document which wouldn't 1453otherwise be handled. This includes both data for which no handlers 1454can be set (like some kinds of DTD declarations) and data which could 1455be reported but which currently has no handler set. The characters 1456are passed exactly as they were present in the XML document except 1457that they will be encoded in UTF-8 or UTF-16. Line boundaries are not 1458normalized. Note that a byte order mark character is not passed to the 1459default handler. There are no guarantees about how characters are 1460divided between calls to the default handler: for example, a comment 1461might be split between multiple calls. Setting the handler with 1462this call has the side effect of turning off expansion of references 1463to internally defined general entities. Instead these references are 1464passed to the default handler.</p> 1465 1466<p>See also <code><a 1467href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1468</div> 1469 1470<div class="handler"> 1471<h4 id="XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</h4> 1472<pre class="setter"> 1473void XMLCALL 1474XML_SetDefaultHandlerExpand(XML_Parser p, 1475 XML_DefaultHandler hndl) 1476</pre> 1477<pre class="signature"> 1478typedef void 1479(XMLCALL *XML_DefaultHandler)(void *userData, 1480 const XML_Char *s, 1481 int len); 1482</pre> 1483<p>This sets a default handler, but doesn't inhibit the expansion of 1484internal entity references. The entity reference will not be passed 1485to the default handler.</p> 1486 1487<p>See also <code><a 1488href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1489</div> 1490 1491<div class="handler"> 1492<h4 id="XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</h4> 1493<pre class="setter"> 1494void XMLCALL 1495XML_SetExternalEntityRefHandler(XML_Parser p, 1496 XML_ExternalEntityRefHandler hndl) 1497</pre> 1498<pre class="signature"> 1499typedef int 1500(XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, 1501 const XML_Char *context, 1502 const XML_Char *base, 1503 const XML_Char *systemId, 1504 const XML_Char *publicId); 1505</pre> 1506<p>Set an external entity reference handler. This handler is also 1507called for processing an external DTD subset if parameter entity parsing 1508is in effect. (See <a href="#XML_SetParamEntityParsing"> 1509<code>XML_SetParamEntityParsing</code></a>.)</p> 1510 1511<p>The <code>context</code> parameter specifies the parsing context in 1512the format expected by the <code>context</code> argument to <code><a 1513href="#XML_ExternalEntityParserCreate" 1514>XML_ExternalEntityParserCreate</a></code>. <code>code</code> is 1515valid only until the handler returns, so if the referenced entity is 1516to be parsed later, it must be copied. <code>context</code> is NULL 1517only when the entity is a parameter entity, which is how one can 1518differentiate between general and parameter entities.</p> 1519 1520<p>The <code>base</code> parameter is the base to use for relative 1521system identifiers. It is set by <code><a 1522href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The 1523<code>publicId</code> parameter is the public id given in the entity 1524declaration and may be NULL. <code>systemId</code> is the system 1525identifier specified in the entity declaration and is never NULL.</p> 1526 1527<p>There are a couple of ways in which this handler differs from 1528others. First, this handler returns a status indicator (an 1529integer). <code>XML_STATUS_OK</code> should be returned for successful 1530handling of the external entity reference. Returning 1531<code>XML_STATUS_ERROR</code> indicates failure, and causes the 1532calling parser to return an 1533<code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> 1534 1535<p>Second, instead of having the user data as its first argument, it 1536receives the parser that encountered the entity reference. This, along 1537with the context parameter, may be used as arguments to a call to 1538<code><a href= "#XML_ExternalEntityParserCreate" 1539>XML_ExternalEntityParserCreate</a></code>. Using the returned 1540parser, the body of the external entity can be recursively parsed.</p> 1541 1542<p>Since this handler may be called recursively, it should not be saving 1543information into global or static variables.</p> 1544</div> 1545 1546<h4 id="XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</h4> 1547<pre class="fcndec"> 1548void XMLCALL 1549XML_SetExternalEntityRefHandlerArg(XML_Parser p, 1550 void *arg) 1551</pre> 1552<div class="fcndef"> 1553<p>Set the argument passed to the ExternalEntityRefHandler. If 1554<code>arg</code> is not NULL, it is the new value passed to the 1555handler set using <code><a href="#XML_SetExternalEntityRefHandler" 1556>XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is 1557NULL, the argument passed to the handler function will be the parser 1558object itself.</p> 1559 1560<p><strong>Note:</strong> 1561The type of <code>arg</code> and the type of the first argument to the 1562ExternalEntityRefHandler do not match. This function takes a 1563<code>void *</code> to be passed to the handler, while the handler 1564accepts an <code>XML_Parser</code>. This is a historical accident, 1565but will not be corrected before Expat 2.0 (at the earliest) to avoid 1566causing compiler warnings for code that's known to work with this 1567API. It is the responsibility of the application code to know the 1568actual type of the argument passed to the handler and to manage it 1569properly.</p> 1570</div> 1571 1572<div class="handler"> 1573<h4 id="XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</h4> 1574<pre class="setter"> 1575void XMLCALL 1576XML_SetSkippedEntityHandler(XML_Parser p, 1577 XML_SkippedEntityHandler handler) 1578</pre> 1579<pre class="signature"> 1580typedef void 1581(XMLCALL *XML_SkippedEntityHandler)(void *userData, 1582 const XML_Char *entityName, 1583 int is_parameter_entity); 1584</pre> 1585<p>Set a skipped entity handler. This is called in two situations:</p> 1586<ol> 1587 <li>An entity reference is encountered for which no declaration 1588 has been read <em>and</em> this is not an error.</li> 1589 <li>An internal entity reference is read, but not expanded, because 1590 <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> 1591 has been called.</li> 1592</ol> 1593<p>The <code>is_parameter_entity</code> argument will be non-zero for 1594a parameter entity and zero for a general entity.</p> <p>Note: Skipped 1595parameter entities in declarations and skipped general entities in 1596attribute values cannot be reported, because the event would be out of 1597sync with the reporting of the declarations or attribute values</p> 1598</div> 1599 1600<div class="handler"> 1601<h4 id="XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</h4> 1602<pre class="setter"> 1603void XMLCALL 1604XML_SetUnknownEncodingHandler(XML_Parser p, 1605 XML_UnknownEncodingHandler enchandler, 1606 void *encodingHandlerData) 1607</pre> 1608<pre class="signature"> 1609typedef int 1610(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, 1611 const XML_Char *name, 1612 XML_Encoding *info); 1613 1614typedef struct { 1615 int map[256]; 1616 void *data; 1617 int (XMLCALL *convert)(void *data, const char *s); 1618 void (XMLCALL *release)(void *data); 1619} XML_Encoding; 1620</pre> 1621<p>Set a handler to deal with encodings other than the <a 1622href="#builtin_encodings">built in set</a>. This should be done before 1623<code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= 1624"#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the 1625given parser.</p> <p>If the handler knows how to deal with an encoding 1626with the given name, it should fill in the <code>info</code> data 1627structure and return <code>XML_STATUS_OK</code>. Otherwise it 1628should return <code>XML_STATUS_ERROR</code>. The handler will be called 1629at most once per parsed (external) entity. The optional application 1630data pointer <code>encodingHandlerData</code> will be passed back to 1631the handler.</p> 1632 1633<p>The map array contains information for every possible leading 1634byte in a byte sequence. If the corresponding value is >= 0, then it's 1635a single byte sequence and the byte encodes that Unicode value. If the 1636value is -1, then that byte is invalid as the initial byte in a sequence. 1637If the value is -n, where n is an integer > 1, then n is the number of 1638bytes in the sequence and the actual conversion is accomplished by a 1639call to the function pointed at by convert. This function may return -1 1640if the sequence itself is invalid. The convert pointer may be null if 1641there are only single byte codes. The data parameter passed to the convert 1642function is the data pointer from <code>XML_Encoding</code>. The 1643string s is <em>NOT</em> null-terminated and points at the sequence of 1644bytes to be converted.</p> 1645 1646<p>The function pointed at by <code>release</code> is called by the 1647parser when it is finished with the encoding. It may be NULL.</p> 1648</div> 1649 1650<div class="handler"> 1651<h4 id="XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</h4> 1652<pre class="setter"> 1653void XMLCALL 1654XML_SetStartNamespaceDeclHandler(XML_Parser p, 1655 XML_StartNamespaceDeclHandler start); 1656</pre> 1657<pre class="signature"> 1658typedef void 1659(XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, 1660 const XML_Char *prefix, 1661 const XML_Char *uri); 1662</pre> 1663<p>Set a handler to be called when a namespace is declared. Namespace 1664declarations occur inside start tags. But the namespace declaration start 1665handler is called before the start tag handler for each namespace declared 1666in that start tag.</p> 1667</div> 1668 1669<div class="handler"> 1670<h4 id="XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</h4> 1671<pre class="setter"> 1672void XMLCALL 1673XML_SetEndNamespaceDeclHandler(XML_Parser p, 1674 XML_EndNamespaceDeclHandler end); 1675</pre> 1676<pre class="signature"> 1677typedef void 1678(XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, 1679 const XML_Char *prefix); 1680</pre> 1681<p>Set a handler to be called when leaving the scope of a namespace 1682declaration. This will be called, for each namespace declaration, 1683after the handler for the end tag of the element in which the 1684namespace was declared.</p> 1685</div> 1686 1687<div class="handler"> 1688<h4 id="XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</h4> 1689<pre class="setter"> 1690void XMLCALL 1691XML_SetNamespaceDeclHandler(XML_Parser p, 1692 XML_StartNamespaceDeclHandler start, 1693 XML_EndNamespaceDeclHandler end) 1694</pre> 1695<p>Sets both namespace declaration handlers with a single call.</p> 1696</div> 1697 1698<div class="handler"> 1699<h4 id="XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</h4> 1700<pre class="setter"> 1701void XMLCALL 1702XML_SetXmlDeclHandler(XML_Parser p, 1703 XML_XmlDeclHandler xmldecl); 1704</pre> 1705<pre class="signature"> 1706typedef void 1707(XMLCALL *XML_XmlDeclHandler)(void *userData, 1708 const XML_Char *version, 1709 const XML_Char *encoding, 1710 int standalone); 1711</pre> 1712<p>Sets a handler that is called for XML declarations and also for 1713text declarations discovered in external entities. The way to 1714distinguish is that the <code>version</code> parameter will be NULL 1715for text declarations. The <code>encoding</code> parameter may be NULL 1716for an XML declaration. The <code>standalone</code> argument will 1717contain -1, 0, or 1 indicating respectively that there was no 1718standalone parameter in the declaration, that it was given as no, or 1719that it was given as yes.</p> 1720</div> 1721 1722<div class="handler"> 1723<h4 id="XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</h4> 1724<pre class="setter"> 1725void XMLCALL 1726XML_SetStartDoctypeDeclHandler(XML_Parser p, 1727 XML_StartDoctypeDeclHandler start); 1728</pre> 1729<pre class="signature"> 1730typedef void 1731(XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, 1732 const XML_Char *doctypeName, 1733 const XML_Char *sysid, 1734 const XML_Char *pubid, 1735 int has_internal_subset); 1736</pre> 1737<p>Set a handler that is called at the start of a DOCTYPE declaration, 1738before any external or internal subset is parsed. Both <code>sysid</code> 1739and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> 1740will be non-zero if the DOCTYPE declaration has an internal subset.</p> 1741</div> 1742 1743<div class="handler"> 1744<h4 id="XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</h4> 1745<pre class="setter"> 1746void XMLCALL 1747XML_SetEndDoctypeDeclHandler(XML_Parser p, 1748 XML_EndDoctypeDeclHandler end); 1749</pre> 1750<pre class="signature"> 1751typedef void 1752(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); 1753</pre> 1754<p>Set a handler that is called at the end of a DOCTYPE declaration, 1755after parsing any external subset.</p> 1756</div> 1757 1758<div class="handler"> 1759<h4 id="XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</h4> 1760<pre class="setter"> 1761void XMLCALL 1762XML_SetDoctypeDeclHandler(XML_Parser p, 1763 XML_StartDoctypeDeclHandler start, 1764 XML_EndDoctypeDeclHandler end); 1765</pre> 1766<p>Set both doctype handlers with one call.</p> 1767</div> 1768 1769<div class="handler"> 1770<h4 id="XML_SetElementDeclHandler">XML_SetElementDeclHandler</h4> 1771<pre class="setter"> 1772void XMLCALL 1773XML_SetElementDeclHandler(XML_Parser p, 1774 XML_ElementDeclHandler eldecl); 1775</pre> 1776<pre class="signature"> 1777typedef void 1778(XMLCALL *XML_ElementDeclHandler)(void *userData, 1779 const XML_Char *name, 1780 XML_Content *model); 1781</pre> 1782<pre class="signature"> 1783enum XML_Content_Type { 1784 XML_CTYPE_EMPTY = 1, 1785 XML_CTYPE_ANY, 1786 XML_CTYPE_MIXED, 1787 XML_CTYPE_NAME, 1788 XML_CTYPE_CHOICE, 1789 XML_CTYPE_SEQ 1790}; 1791 1792enum XML_Content_Quant { 1793 XML_CQUANT_NONE, 1794 XML_CQUANT_OPT, 1795 XML_CQUANT_REP, 1796 XML_CQUANT_PLUS 1797}; 1798 1799typedef struct XML_cp XML_Content; 1800 1801struct XML_cp { 1802 enum XML_Content_Type type; 1803 enum XML_Content_Quant quant; 1804 const XML_Char * name; 1805 unsigned int numchildren; 1806 XML_Content * children; 1807}; 1808</pre> 1809<p>Sets a handler for element declarations in a DTD. The handler gets 1810called with the name of the element in the declaration and a pointer 1811to a structure that contains the element model. It is the 1812application's responsibility to free this data structure using 1813<code><a href="#XML_FreeContentModel" 1814>XML_FreeContentModel</a></code>.</p> 1815 1816<p>The <code>model</code> argument is the root of a tree of 1817<code>XML_Content</code> nodes. If <code>type</code> equals 1818<code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then 1819<code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other 1820fields will be zero or NULL. If <code>type</code> is 1821<code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be 1822<code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and 1823<code>numchildren</code> will contain the number of elements that are 1824allowed to be mixed in and <code>children</code> points to an array of 1825<code>XML_Content</code> structures that will all have type 1826XML_CTYPE_NAME with no quantification. Only the root node can be type 1827<code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or 1828<code>XML_CTYPE_MIXED</code>.</p> 1829 1830<p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field 1831points to the name and the <code>numchildren</code> and 1832<code>children</code> fields will be zero and NULL. The 1833<code>quant</code> field will indicate any quantifiers placed on the 1834name.</p> 1835 1836<p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> 1837indicate a choice or sequence respectively. The 1838<code>numchildren</code> field indicates how many nodes in the choice 1839or sequence and <code>children</code> points to the nodes.</p> 1840</div> 1841 1842<div class="handler"> 1843<h4 id="XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</h4> 1844<pre class="setter"> 1845void XMLCALL 1846XML_SetAttlistDeclHandler(XML_Parser p, 1847 XML_AttlistDeclHandler attdecl); 1848</pre> 1849<pre class="signature"> 1850typedef void 1851(XMLCALL *XML_AttlistDeclHandler)(void *userData, 1852 const XML_Char *elname, 1853 const XML_Char *attname, 1854 const XML_Char *att_type, 1855 const XML_Char *dflt, 1856 int isrequired); 1857</pre> 1858<p>Set a handler for attlist declarations in the DTD. This handler is 1859called for <em>each</em> attribute. So a single attlist declaration 1860with multiple attributes declared will generate multiple calls to this 1861handler. The <code>elname</code> parameter returns the name of the 1862element for which the attribute is being declared. The attribute name 1863is in the <code>attname</code> parameter. The attribute type is in the 1864<code>att_type</code> parameter. It is the string representing the 1865type in the declaration with whitespace removed.</p> 1866 1867<p>The <code>dflt</code> parameter holds the default value. It will be 1868NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can 1869distinguish these two cases by checking the <code>isrequired</code> 1870parameter, which will be true in the case of "#REQUIRED" attributes. 1871Attributes which are "#FIXED" will have also have a true 1872<code>isrequired</code>, but they will have the non-NULL fixed value 1873in the <code>dflt</code> parameter.</p> 1874</div> 1875 1876<div class="handler"> 1877<h4 id="XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</h4> 1878<pre class="setter"> 1879void XMLCALL 1880XML_SetEntityDeclHandler(XML_Parser p, 1881 XML_EntityDeclHandler handler); 1882</pre> 1883<pre class="signature"> 1884typedef void 1885(XMLCALL *XML_EntityDeclHandler)(void *userData, 1886 const XML_Char *entityName, 1887 int is_parameter_entity, 1888 const XML_Char *value, 1889 int value_length, 1890 const XML_Char *base, 1891 const XML_Char *systemId, 1892 const XML_Char *publicId, 1893 const XML_Char *notationName); 1894</pre> 1895<p>Sets a handler that will be called for all entity declarations. 1896The <code>is_parameter_entity</code> argument will be non-zero in the 1897case of parameter entities and zero otherwise.</p> 1898 1899<p>For internal entities (<code><!ENTITY foo "bar"></code>), 1900<code>value</code> will be non-NULL and <code>systemId</code>, 1901<code>publicId</code>, and <code>notationName</code> will all be NULL. 1902The value string is <em>not</em> NULL terminated; the length is 1903provided in the <code>value_length</code> parameter. Do not use 1904<code>value_length</code> to test for internal entities, since it is 1905legal to have zero-length values. Instead check for whether or not 1906<code>value</code> is NULL.</p> <p>The <code>notationName</code> 1907argument will have a non-NULL value only for unparsed entity 1908declarations.</p> 1909</div> 1910 1911<div class="handler"> 1912<h4 id="XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</h4> 1913<pre class="setter"> 1914void XMLCALL 1915XML_SetUnparsedEntityDeclHandler(XML_Parser p, 1916 XML_UnparsedEntityDeclHandler h) 1917</pre> 1918<pre class="signature"> 1919typedef void 1920(XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, 1921 const XML_Char *entityName, 1922 const XML_Char *base, 1923 const XML_Char *systemId, 1924 const XML_Char *publicId, 1925 const XML_Char *notationName); 1926</pre> 1927<p>Set a handler that receives declarations of unparsed entities. These 1928are entity declarations that have a notation (NDATA) field:</p> 1929 1930<div id="eg"><pre> 1931<!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> 1932</pre></div> 1933<p>This handler is obsolete and is provided for backwards 1934compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" 1935>XML_SetEntityDeclHandler</a>.</p> 1936</div> 1937 1938<div class="handler"> 1939<h4 id="XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</h4> 1940<pre class="setter"> 1941void XMLCALL 1942XML_SetNotationDeclHandler(XML_Parser p, 1943 XML_NotationDeclHandler h) 1944</pre> 1945<pre class="signature"> 1946typedef void 1947(XMLCALL *XML_NotationDeclHandler)(void *userData, 1948 const XML_Char *notationName, 1949 const XML_Char *base, 1950 const XML_Char *systemId, 1951 const XML_Char *publicId); 1952</pre> 1953<p>Set a handler that receives notation declarations.</p> 1954</div> 1955 1956<div class="handler"> 1957<h4 id="XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</h4> 1958<pre class="setter"> 1959void XMLCALL 1960XML_SetNotStandaloneHandler(XML_Parser p, 1961 XML_NotStandaloneHandler h) 1962</pre> 1963<pre class="signature"> 1964typedef int 1965(XMLCALL *XML_NotStandaloneHandler)(void *userData); 1966</pre> 1967<p>Set a handler that is called if the document is not "standalone". 1968This happens when there is an external subset or a reference to a 1969parameter entity, but does not have standalone set to "yes" in an XML 1970declaration. If this handler returns <code>XML_STATUS_ERROR</code>, 1971then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> 1972error.</p> 1973</div> 1974 1975<h3><a name="position">Parse position and error reporting functions</a></h3> 1976 1977<p>These are the functions you'll want to call when the parse 1978functions return <code>XML_STATUS_ERROR</code> (a parse error has 1979occurred), although the position reporting functions are useful outside 1980of errors. The position reported is the byte position (in the original 1981document or entity encoding) of the first of the sequence of 1982characters that generated the current event (or the error that caused 1983the parse functions to return <code>XML_STATUS_ERROR</code>.) The 1984exceptions are callbacks triggered by declarations in the document 1985prologue, in which case they exact position reported is somewhere in the 1986relevant markup, but not necessarily as meaningful as for other 1987events.</p> 1988 1989<p>The position reporting functions are accurate only outside of the 1990DTD. In other words, they usually return bogus information when 1991called from within a DTD declaration handler.</p> 1992 1993<h4 id="XML_GetErrorCode">XML_GetErrorCode</h4> 1994<pre class="fcndec"> 1995enum XML_Error XMLCALL 1996XML_GetErrorCode(XML_Parser p); 1997</pre> 1998<div class="fcndef"> 1999Return what type of error has occurred. 2000</div> 2001 2002<h4 id="XML_ErrorString">XML_ErrorString</h4> 2003<pre class="fcndec"> 2004const XML_LChar * XMLCALL 2005XML_ErrorString(enum XML_Error code); 2006</pre> 2007<div class="fcndef"> 2008Return a string describing the error corresponding to code. 2009The code should be one of the enums that can be returned from 2010<code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. 2011</div> 2012 2013<h4 id="XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</h4> 2014<pre class="fcndec"> 2015XML_Index XMLCALL 2016XML_GetCurrentByteIndex(XML_Parser p); 2017</pre> 2018<div class="fcndef"> 2019Return the byte offset of the position. This always corresponds to 2020the values returned by <code><a href= "#XML_GetCurrentLineNumber" 2021>XML_GetCurrentLineNumber</a></code> and <code><a href= 2022"#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. 2023</div> 2024 2025<h4 id="XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</h4> 2026<pre class="fcndec"> 2027XML_Size XMLCALL 2028XML_GetCurrentLineNumber(XML_Parser p); 2029</pre> 2030<div class="fcndef"> 2031Return the line number of the position. The first line is reported as 2032<code>1</code>. 2033</div> 2034 2035<h4 id="XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</h4> 2036<pre class="fcndec"> 2037XML_Size XMLCALL 2038XML_GetCurrentColumnNumber(XML_Parser p); 2039</pre> 2040<div class="fcndef"> 2041Return the offset, from the beginning of the current line, of 2042the position. 2043</div> 2044 2045<h4 id="XML_GetCurrentByteCount">XML_GetCurrentByteCount</h4> 2046<pre class="fcndec"> 2047int XMLCALL 2048XML_GetCurrentByteCount(XML_Parser p); 2049</pre> 2050<div class="fcndef"> 2051Return the number of bytes in the current event. Returns 2052<code>0</code> if the event is inside a reference to an internal 2053entity and for the end-tag event for empty element tags (the later can 2054be used to distinguish empty-element tags from empty elements using 2055separate start and end tags). 2056</div> 2057 2058<h4 id="XML_GetInputContext">XML_GetInputContext</h4> 2059<pre class="fcndec"> 2060const char * XMLCALL 2061XML_GetInputContext(XML_Parser p, 2062 int *offset, 2063 int *size); 2064</pre> 2065<div class="fcndef"> 2066 2067<p>Returns the parser's input buffer, sets the integer pointed at by 2068<code>offset</code> to the offset within this buffer of the current 2069parse position, and set the integer pointed at by <code>size</code> to 2070the size of the returned buffer.</p> 2071 2072<p>This should only be called from within a handler during an active 2073parse and the returned buffer should only be referred to from within 2074the handler that made the call. This input buffer contains the 2075untranslated bytes of the input.</p> 2076 2077<p>Only a limited amount of context is kept, so if the event 2078triggering a call spans over a very large amount of input, the actual 2079parse position may be before the beginning of the buffer.</p> 2080 2081<p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always 2082return NULL.</p> 2083</div> 2084 2085<h3><a name="billion-laughs">Billion Laughs Attack Protection</a></h3> 2086 2087<p>The functions in this section configure the built-in 2088 protection against various forms of 2089 <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a>.</p> 2090 2091<h4 id="XML_SetBillionLaughsAttackProtectionMaximumAmplification">XML_SetBillionLaughsAttackProtectionMaximumAmplification</h4> 2092<pre class="fcndec"> 2093/* Added in Expat 2.4.0. */ 2094XML_Bool XMLCALL 2095XML_SetBillionLaughsAttackProtectionMaximumAmplification(XML_Parser p, 2096 float maximumAmplificationFactor); 2097</pre> 2098<div class="fcndef"> 2099 <p> 2100 Sets the maximum tolerated amplification factor 2101 for protection against 2102 <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a> 2103 (default: <code>100.0</code>) 2104 of parser <code>p</code> to <code>maximumAmplificationFactor</code>, and 2105 returns <code>XML_TRUE</code> upon success and <code>XML_FALSE</code> upon error. 2106 </p> 2107 2108 The amplification factor is calculated as .. 2109 <pre> 2110 amplification := (direct + indirect) / direct 2111 </pre> 2112 .. while parsing, whereas 2113 <code>direct</code> is the number of bytes read from the primary document in parsing and 2114 <code>indirect</code> is the number of bytes added by expanding entities and reading of external DTD files, combined. 2115 2116 <p>For a call to <code>XML_SetBillionLaughsAttackProtectionMaximumAmplification</code> to succeed:</p> 2117 <ul> 2118 <li>parser <code>p</code> must be a non-<code>NULL</code> root parser (without any parent parsers) and</li> 2119 <li><code>maximumAmplificationFactor</code> must be non-<code>NaN</code> and greater than or equal to <code>1.0</code>.</li> 2120 </ul> 2121 2122 <p> 2123 <strong>Note:</strong> 2124 If you ever need to increase this value for non-attack payload, 2125 please <a href="https://github.com/libexpat/libexpat/issues">file a bug report</a>. 2126 </p> 2127 2128 <p> 2129 <strong>Note:</strong> 2130 Peak amplifications 2131 of factor 15,000 for the entire payload and 2132 of factor 30,000 in the middle of parsing 2133 have been observed with small benign files in practice. 2134 2135 So if you do reduce the maximum allowed amplification, 2136 please make sure that the activation threshold is still big enough 2137 to not end up with undesired false positives (i.e. benign files being rejected). 2138 </p> 2139</div> 2140 2141<h4 id="XML_SetBillionLaughsAttackProtectionActivationThreshold">XML_SetBillionLaughsAttackProtectionActivationThreshold</h4> 2142<pre class="fcndec"> 2143/* Added in Expat 2.4.0. */ 2144XML_Bool XMLCALL 2145XML_SetBillionLaughsAttackProtectionActivationThreshold(XML_Parser p, 2146 unsigned long long activationThresholdBytes); 2147</pre> 2148<div class="fcndef"> 2149 <p> 2150 Sets number of output bytes (including amplification from entity expansion and reading DTD files) 2151 needed to activate protection against 2152 <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a> 2153 (default: <code>8 MiB</code>) 2154 of parser <code>p</code> to <code>activationThresholdBytes</code>, and 2155 returns <code>XML_TRUE</code> upon success and <code>XML_FALSE</code> upon error. 2156 </p> 2157 2158 <p>For a call to <code>XML_SetBillionLaughsAttackProtectionActivationThreshold</code> to succeed:</p> 2159 <ul> 2160 <li>parser <code>p</code> must be a non-<code>NULL</code> root parser (without any parent parsers).</li> 2161 </ul> 2162 2163 <p> 2164 <strong>Note:</strong> 2165 If you ever need to increase this value for non-attack payload, 2166 please <a href="https://github.com/libexpat/libexpat/issues">file a bug report</a>. 2167 </p> 2168 2169 <p> 2170 <strong>Note:</strong> 2171 Activation thresholds below 4 MiB are known to break support for 2172 <a href="https://en.wikipedia.org/wiki/Darwin_Information_Typing_Architecture">DITA</a> 1.3 payload 2173 and are hence not recommended. 2174 </p> 2175</div> 2176 2177<h3><a name="miscellaneous">Miscellaneous functions</a></h3> 2178 2179<p>The functions in this section either obtain state information from 2180the parser or can be used to dynamically set parser options.</p> 2181 2182<h4 id="XML_SetUserData">XML_SetUserData</h4> 2183<pre class="fcndec"> 2184void XMLCALL 2185XML_SetUserData(XML_Parser p, 2186 void *userData); 2187</pre> 2188<div class="fcndef"> 2189This sets the user data pointer that gets passed to handlers. It 2190overwrites any previous value for this pointer. Note that the 2191application is responsible for freeing the memory associated with 2192<code>userData</code> when it is finished with the parser. So if you 2193call this when there's already a pointer there, and you haven't freed 2194the memory associated with it, then you've probably just leaked 2195memory. 2196</div> 2197 2198<h4 id="XML_GetUserData">XML_GetUserData</h4> 2199<pre class="fcndec"> 2200void * XMLCALL 2201XML_GetUserData(XML_Parser p); 2202</pre> 2203<div class="fcndef"> 2204This returns the user data pointer that gets passed to handlers. 2205It is actually implemented as a macro. 2206</div> 2207 2208<h4 id="XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</h4> 2209<pre class="fcndec"> 2210void XMLCALL 2211XML_UseParserAsHandlerArg(XML_Parser p); 2212</pre> 2213<div class="fcndef"> 2214After this is called, handlers receive the parser in their 2215<code>userData</code> arguments. The user data can still be obtained 2216using the <code><a href= "#XML_GetUserData" 2217>XML_GetUserData</a></code> function. 2218</div> 2219 2220<h4 id="XML_SetBase">XML_SetBase</h4> 2221<pre class="fcndec"> 2222enum XML_Status XMLCALL 2223XML_SetBase(XML_Parser p, 2224 const XML_Char *base); 2225</pre> 2226<div class="fcndef"> 2227Set the base to be used for resolving relative URIs in system 2228identifiers. The return value is <code>XML_STATUS_ERROR</code> if 2229there's no memory to store base, otherwise it's 2230<code>XML_STATUS_OK</code>. 2231</div> 2232 2233<h4 id="XML_GetBase">XML_GetBase</h4> 2234<pre class="fcndec"> 2235const XML_Char * XMLCALL 2236XML_GetBase(XML_Parser p); 2237</pre> 2238<div class="fcndef"> 2239Return the base for resolving relative URIs. 2240</div> 2241 2242<h4 id="XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</h4> 2243<pre class="fcndec"> 2244int XMLCALL 2245XML_GetSpecifiedAttributeCount(XML_Parser p); 2246</pre> 2247<div class="fcndef"> 2248When attributes are reported to the start handler in the atts vector, 2249attributes that were explicitly set in the element occur before any 2250attributes that receive their value from default information in an 2251ATTLIST declaration. This function returns the number of attributes 2252that were explicitly set times two, thus giving the offset in the 2253<code>atts</code> array passed to the start tag handler of the first 2254attribute set due to defaults. It supplies information for the last 2255call to a start handler. If called inside a start handler, then that 2256means the current call. 2257</div> 2258 2259<h4 id="XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</h4> 2260<pre class="fcndec"> 2261int XMLCALL 2262XML_GetIdAttributeIndex(XML_Parser p); 2263</pre> 2264<div class="fcndef"> 2265Returns the index of the ID attribute passed in the atts array in the 2266last call to <code><a href= "#XML_StartElementHandler" 2267>XML_StartElementHandler</a></code>, or -1 if there is no ID 2268attribute. If called inside a start handler, then that means the 2269current call. 2270</div> 2271 2272<h4 id="XML_GetAttributeInfo">XML_GetAttributeInfo</h4> 2273<pre class="fcndec"> 2274const XML_AttrInfo * XMLCALL 2275XML_GetAttributeInfo(XML_Parser parser); 2276</pre> 2277<pre class="signature"> 2278typedef struct { 2279 XML_Index nameStart; /* Offset to beginning of the attribute name. */ 2280 XML_Index nameEnd; /* Offset after the attribute name's last byte. */ 2281 XML_Index valueStart; /* Offset to beginning of the attribute value. */ 2282 XML_Index valueEnd; /* Offset after the attribute value's last byte. */ 2283} XML_AttrInfo; 2284</pre> 2285<div class="fcndef"> 2286Returns an array of <code>XML_AttrInfo</code> structures for the 2287attribute/value pairs passed in the last call to the 2288<code>XML_StartElementHandler</code> that were specified 2289in the start-tag rather than defaulted. Each attribute/value pair counts 2290as 1; thus the number of entries in the array is 2291<code>XML_GetSpecifiedAttributeCount(parser) / 2</code>. 2292</div> 2293 2294<h4 id="XML_SetEncoding">XML_SetEncoding</h4> 2295<pre class="fcndec"> 2296enum XML_Status XMLCALL 2297XML_SetEncoding(XML_Parser p, 2298 const XML_Char *encoding); 2299</pre> 2300<div class="fcndef"> 2301Set the encoding to be used by the parser. It is equivalent to 2302passing a non-null encoding argument to the parser creation functions. 2303It must not be called after <code><a href= "#XML_Parse" 2304>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 2305>XML_ParseBuffer</a></code> have been called on the given parser. 2306Returns <code>XML_STATUS_OK</code> on success or 2307<code>XML_STATUS_ERROR</code> on error. 2308</div> 2309 2310<h4 id="XML_SetParamEntityParsing">XML_SetParamEntityParsing</h4> 2311<pre class="fcndec"> 2312int XMLCALL 2313XML_SetParamEntityParsing(XML_Parser p, 2314 enum XML_ParamEntityParsing code); 2315</pre> 2316<div class="fcndef"> 2317This enables parsing of parameter entities, including the external 2318parameter entity that is the external DTD subset, according to 2319<code>code</code>. 2320The choices for <code>code</code> are: 2321<ul> 2322<li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> 2323<li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> 2324<li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> 2325</ul> 2326<b>Note:</b> If <code>XML_SetParamEntityParsing</code> is called after 2327<code>XML_Parse</code> or <code>XML_ParseBuffer</code>, then it has 2328no effect and will always return 0. 2329</div> 2330 2331<h4 id="XML_SetHashSalt">XML_SetHashSalt</h4> 2332<pre class="fcndec"> 2333int XMLCALL 2334XML_SetHashSalt(XML_Parser p, 2335 unsigned long hash_salt); 2336</pre> 2337<div class="fcndef"> 2338Sets the hash salt to use for internal hash calculations. 2339Helps in preventing DoS attacks based on predicting hash 2340function behavior. In order to have an effect this must be called 2341before parsing has started. Returns 1 if successful, 0 when called 2342after <code>XML_Parse</code> or <code>XML_ParseBuffer</code>. 2343<p><b>Note:</b> This call is optional, as the parser will auto-generate 2344a new random salt value if no value has been set at the start of parsing.</p> 2345<p><b>Note:</b> One should not call <code>XML_SetHashSalt</code> with a 2346hash salt value of 0, as this value is used as sentinel value to indicate 2347that <code>XML_SetHashSalt</code> has <b>not</b> been called. Consequently 2348such a call will have no effect, even if it returns 1.</p> 2349</div> 2350 2351<h4 id="XML_UseForeignDTD">XML_UseForeignDTD</h4> 2352<pre class="fcndec"> 2353enum XML_Error XMLCALL 2354XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); 2355</pre> 2356<div class="fcndef"> 2357<p>This function allows an application to provide an external subset 2358for the document type declaration for documents which do not specify 2359an external subset of their own. For documents which specify an 2360external subset in their DOCTYPE declaration, the application-provided 2361subset will be ignored. If the document does not contain a DOCTYPE 2362declaration at all and <code>useDTD</code> is true, the 2363application-provided subset will be parsed, but the 2364<code>startDoctypeDeclHandler</code> and 2365<code>endDoctypeDeclHandler</code> functions, if set, will not be 2366called. The setting of parameter entity parsing, controlled using 2367<code><a href= "#XML_SetParamEntityParsing" 2368>XML_SetParamEntityParsing</a></code>, will be honored.</p> 2369 2370<p>The application-provided external subset is read by calling the 2371external entity reference handler set via <code><a href= 2372"#XML_SetExternalEntityRefHandler" 2373>XML_SetExternalEntityRefHandler</a></code> with both 2374<code>publicId</code> and <code>systemId</code> set to NULL.</p> 2375 2376<p>If this function is called after parsing has begun, it returns 2377<code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores 2378<code>useDTD</code>. If called when Expat has been compiled without 2379DTD support, it returns 2380<code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it 2381returns <code>XML_ERROR_NONE</code>.</p> 2382 2383<p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing 2384<code>useDTD == XML_TRUE</code> will make the parser behave as if 2385the document had a DTD with an external subset. This holds true even if 2386the external entity reference handler returns without action.</p> 2387</div> 2388 2389<h4 id="XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</h4> 2390<pre class="fcndec"> 2391void XMLCALL 2392XML_SetReturnNSTriplet(XML_Parser parser, 2393 int do_nst); 2394</pre> 2395<div class="fcndef"> 2396<p> 2397This function only has an effect when using a parser created with 2398<code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, 2399i.e. when namespace processing is in effect. The <code>do_nst</code> 2400sets whether or not prefixes are returned with names qualified with a 2401namespace prefix. If this function is called with <code>do_nst</code> 2402non-zero, then afterwards namespace qualified names (that is qualified 2403with a prefix as opposed to belonging to a default namespace) are 2404returned as a triplet with the three parts separated by the namespace 2405separator specified when the parser was created. The order of 2406returned parts is URI, local name, and prefix.</p> <p>If 2407<code>do_nst</code> is zero, then namespaces are reported in the 2408default manner, URI then local_name separated by the namespace 2409separator.</p> 2410</div> 2411 2412<h4 id="XML_DefaultCurrent">XML_DefaultCurrent</h4> 2413<pre class="fcndec"> 2414void XMLCALL 2415XML_DefaultCurrent(XML_Parser parser); 2416</pre> 2417<div class="fcndef"> 2418This can be called within a handler for a start element, end element, 2419processing instruction or character data. It causes the corresponding 2420markup to be passed to the default handler set by <code><a 2421href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or 2422<code><a href="#XML_SetDefaultHandlerExpand" 2423>XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is 2424not a default handler. 2425</div> 2426 2427<h4 id="XML_ExpatVersion">XML_ExpatVersion</h4> 2428<pre class="fcndec"> 2429XML_LChar * XMLCALL 2430XML_ExpatVersion(); 2431</pre> 2432<div class="fcndef"> 2433Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). 2434</div> 2435 2436<h4 id="XML_ExpatVersionInfo">XML_ExpatVersionInfo</h4> 2437<pre class="fcndec"> 2438struct XML_Expat_Version XMLCALL 2439XML_ExpatVersionInfo(); 2440</pre> 2441<pre class="signature"> 2442typedef struct { 2443 int major; 2444 int minor; 2445 int micro; 2446} XML_Expat_Version; 2447</pre> 2448<div class="fcndef"> 2449Return the library version information as a structure. 2450Some macros are also defined that support compile-time tests of the 2451library version: 2452<ul> 2453<li><code>XML_MAJOR_VERSION</code></li> 2454<li><code>XML_MINOR_VERSION</code></li> 2455<li><code>XML_MICRO_VERSION</code></li> 2456</ul> 2457Testing these constants is currently the best way to determine if 2458particular parts of the Expat API are available. 2459</div> 2460 2461<h4 id="XML_GetFeatureList">XML_GetFeatureList</h4> 2462<pre class="fcndec"> 2463const XML_Feature * XMLCALL 2464XML_GetFeatureList(); 2465</pre> 2466<pre class="signature"> 2467enum XML_FeatureEnum { 2468 XML_FEATURE_END = 0, 2469 XML_FEATURE_UNICODE, 2470 XML_FEATURE_UNICODE_WCHAR_T, 2471 XML_FEATURE_DTD, 2472 XML_FEATURE_CONTEXT_BYTES, 2473 XML_FEATURE_MIN_SIZE, 2474 XML_FEATURE_SIZEOF_XML_CHAR, 2475 XML_FEATURE_SIZEOF_XML_LCHAR, 2476 XML_FEATURE_NS, 2477 XML_FEATURE_LARGE_SIZE 2478}; 2479 2480typedef struct { 2481 enum XML_FeatureEnum feature; 2482 XML_LChar *name; 2483 long int value; 2484} XML_Feature; 2485</pre> 2486<div class="fcndef"> 2487<p>Returns a list of "feature" records, providing details on how 2488Expat was configured at compile time. Most applications should not 2489need to worry about this, but this information is otherwise not 2490available from Expat. This function allows code that does need to 2491check these features to do so at runtime.</p> 2492 2493<p>The return value is an array of <code>XML_Feature</code>, 2494terminated by a record with a <code>feature</code> of 2495<code>XML_FEATURE_END</code> and <code>name</code> of NULL, 2496identifying the feature-test macros Expat was compiled with. Since an 2497application that requires this kind of information needs to determine 2498the type of character the <code>name</code> points to, records for the 2499<code>XML_FEATURE_SIZEOF_XML_CHAR</code> and 2500<code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the 2501beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> 2502and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at 2503all.</p> 2504 2505<p>Some features have an associated value. If there isn't an 2506associated value, the <code>value</code> field is set to 0. At this 2507time, the following features have been defined to have values:</p> 2508 2509<dl> 2510 <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> 2511 <dd>The number of bytes occupied by one <code>XML_Char</code> 2512 character.</dd> 2513 <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> 2514 <dd>The number of bytes occupied by one <code>XML_LChar</code> 2515 character.</dd> 2516 <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> 2517 <dd>The maximum number of characters of context which can be 2518 reported by <code><a href= "#XML_GetInputContext" 2519 >XML_GetInputContext</a></code>.</dd> 2520</dl> 2521</div> 2522 2523<h4 id="XML_FreeContentModel">XML_FreeContentModel</h4> 2524<pre class="fcndec"> 2525void XMLCALL 2526XML_FreeContentModel(XML_Parser parser, XML_Content *model); 2527</pre> 2528<div class="fcndef"> 2529Function to deallocate the <code>model</code> argument passed to the 2530<code>XML_ElementDeclHandler</code> callback set using <code><a 2531href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. 2532This function should not be used for any other purpose. 2533</div> 2534 2535<p>The following functions allow external code to share the memory 2536allocator an <code>XML_Parser</code> has been configured to use. This 2537is especially useful for third-party libraries that interact with a 2538parser object created by application code, or heavily layered 2539applications. This can be essential when using dynamically loaded 2540libraries which use different C standard libraries (this can happen on 2541Windows, at least).</p> 2542 2543<h4 id="XML_MemMalloc">XML_MemMalloc</h4> 2544<pre class="fcndec"> 2545void * XMLCALL 2546XML_MemMalloc(XML_Parser parser, size_t size); 2547</pre> 2548<div class="fcndef"> 2549Allocate <code>size</code> bytes of memory using the allocator the 2550<code>parser</code> object has been configured to use. Returns a 2551pointer to the memory or NULL on failure. Memory allocated in this 2552way must be freed using <code><a href="#XML_MemFree" 2553>XML_MemFree</a></code>. 2554</div> 2555 2556<h4 id="XML_MemRealloc">XML_MemRealloc</h4> 2557<pre class="fcndec"> 2558void * XMLCALL 2559XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); 2560</pre> 2561<div class="fcndef"> 2562Allocate <code>size</code> bytes of memory using the allocator the 2563<code>parser</code> object has been configured to use. 2564<code>ptr</code> must point to a block of memory allocated by <code><a 2565href="#XML_MemMalloc" >XML_MemMalloc</a></code> or 2566<code>XML_MemRealloc</code>, or be NULL. This function tries to 2567expand the block pointed to by <code>ptr</code> if possible. Returns 2568a pointer to the memory or NULL on failure. On success, the original 2569block has either been expanded or freed. On failure, the original 2570block has not been freed; the caller is responsible for freeing the 2571original block. Memory allocated in this way must be freed using 2572<code><a href="#XML_MemFree" 2573>XML_MemFree</a></code>. 2574</div> 2575 2576<h4 id="XML_MemFree">XML_MemFree</h4> 2577<pre class="fcndec"> 2578void XMLCALL 2579XML_MemFree(XML_Parser parser, void *ptr); 2580</pre> 2581<div class="fcndef"> 2582Free a block of memory pointed to by <code>ptr</code>. The block must 2583have been allocated by <code><a href="#XML_MemMalloc" 2584>XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. 2585</div> 2586 2587<hr /> 2588 2589 <div class="footer"> 2590 Found a bug in the documentation? 2591 <a href="https://github.com/libexpat/libexpat/issues">Please file a bug report.</a> 2592 </div> 2593 2594</div> 2595</body> 2596</html> 2597
