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| |_| XML parser |
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| Copyright (c) 2000 Clark Cooper <coopercc@users.sourceforge.net> |
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| <title>Expat XML Parser</title> |
| <meta name="author" content="Clark Cooper, coopercc@netheaven.com" /> |
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| </head> |
| <body> |
| <div> |
| <h1> |
| The Expat XML Parser |
| <small>Release 2.4.7</small> |
| </h1> |
| </div> |
| <div class="content"> |
| |
| <p>Expat is a library, written in C, for parsing XML documents. It's |
| the underlying XML parser for the open source Mozilla project, Perl's |
| <code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and |
| other open-source XML parsers.</p> |
| |
| <p>This library is the creation of James Clark, who's also given us |
| groff (an nroff look-alike), Jade (an implementation of ISO's DSSSL |
| stylesheet language for SGML), XP (a Java XML parser package), XT (a |
| Java XSL engine). James was also the technical lead on the XML |
| Working Group at W3C that produced the XML specification.</p> |
| |
| <p>This is free software, licensed under the <a |
| href="../COPYING">MIT/X Consortium license</a>. You may download it |
| from <a href="http://www.libexpat.org/">the Expat home page</a>. |
| </p> |
| |
| <p>The bulk of this document was originally commissioned as an article |
| by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed |
| Clark Cooper to retain copyright and to distribute it with Expat. |
| This version has been substantially extended to include documentation |
| on features which have been added since the original article was |
| published, and additional information on using the original |
| interface.</p> |
| |
| <hr /> |
| <h2>Table of Contents</h2> |
| <ul> |
| <li><a href="#overview">Overview</a></li> |
| <li><a href="#building">Building and Installing</a></li> |
| <li><a href="#using">Using Expat</a></li> |
| <li><a href="#reference">Reference</a> |
| <ul> |
| <li><a href="#creation">Parser Creation Functions</a> |
| <ul> |
| <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li> |
| <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li> |
| <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li> |
| <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li> |
| <li><a href="#XML_ParserFree">XML_ParserFree</a></li> |
| <li><a href="#XML_ParserReset">XML_ParserReset</a></li> |
| </ul> |
| </li> |
| <li><a href="#parsing">Parsing Functions</a> |
| <ul> |
| <li><a href="#XML_Parse">XML_Parse</a></li> |
| <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li> |
| <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li> |
| <li><a href="#XML_StopParser">XML_StopParser</a></li> |
| <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li> |
| <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li> |
| </ul> |
| </li> |
| <li><a href="#setting">Handler Setting Functions</a> |
| <ul> |
| <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li> |
| <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li> |
| <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li> |
| <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li> |
| <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li> |
| <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li> |
| <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li> |
| <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li> |
| <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li> |
| <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li> |
| <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li> |
| <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li> |
| <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li> |
| <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li> |
| <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li> |
| <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li> |
| <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li> |
| <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li> |
| <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li> |
| <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li> |
| <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li> |
| <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li> |
| <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li> |
| <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li> |
| <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li> |
| <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li> |
| <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li> |
| <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li> |
| </ul> |
| </li> |
| <li><a href="#position">Parse Position and Error Reporting Functions</a> |
| <ul> |
| <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li> |
| <li><a href="#XML_ErrorString">XML_ErrorString</a></li> |
| <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li> |
| <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li> |
| <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li> |
| <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li> |
| <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li> |
| </ul> |
| </li> |
| <li> |
| <a href="#billion-laughs">Billion Laughs Attack Protection</a> |
| <ul> |
| <li><a href="#XML_SetBillionLaughsAttackProtectionMaximumAmplification">XML_SetBillionLaughsAttackProtectionMaximumAmplification</a></li> |
| <li><a href="#XML_SetBillionLaughsAttackProtectionActivationThreshold">XML_SetBillionLaughsAttackProtectionActivationThreshold</a></li> |
| </ul> |
| </li> |
| <li><a href="#miscellaneous">Miscellaneous Functions</a> |
| <ul> |
| <li><a href="#XML_SetUserData">XML_SetUserData</a></li> |
| <li><a href="#XML_GetUserData">XML_GetUserData</a></li> |
| <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li> |
| <li><a href="#XML_SetBase">XML_SetBase</a></li> |
| <li><a href="#XML_GetBase">XML_GetBase</a></li> |
| <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li> |
| <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li> |
| <li><a href="#XML_GetAttributeInfo">XML_GetAttributeInfo</a></li> |
| <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li> |
| <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li> |
| <li><a href="#XML_SetHashSalt">XML_SetHashSalt</a></li> |
| <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li> |
| <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li> |
| <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li> |
| <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li> |
| <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li> |
| <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li> |
| <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li> |
| <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li> |
| <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li> |
| <li><a href="#XML_MemFree">XML_MemFree</a></li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| |
| <hr /> |
| <h2><a name="overview">Overview</a></h2> |
| |
| <p>Expat is a stream-oriented parser. You register callback (or |
| handler) functions with the parser and then start feeding it the |
| document. As the parser recognizes parts of the document, it will |
| call the appropriate handler for that part (if you've registered one.) |
| The document is fed to the parser in pieces, so you can start parsing |
| before you have all the document. This also allows you to parse really |
| huge documents that won't fit into memory.</p> |
| |
| <p>Expat can be intimidating due to the many kinds of handlers and |
| options you can set. But you only need to learn four functions in |
| order to do 90% of what you'll want to do with it:</p> |
| |
| <dl> |
| |
| <dt><code><a href= "#XML_ParserCreate" |
| >XML_ParserCreate</a></code></dt> |
| <dd>Create a new parser object.</dd> |
| |
| <dt><code><a href= "#XML_SetElementHandler" |
| >XML_SetElementHandler</a></code></dt> |
| <dd>Set handlers for start and end tags.</dd> |
| |
| <dt><code><a href= "#XML_SetCharacterDataHandler" |
| >XML_SetCharacterDataHandler</a></code></dt> |
| <dd>Set handler for text.</dd> |
| |
| <dt><code><a href= "#XML_Parse" |
| >XML_Parse</a></code></dt> |
| <dd>Pass a buffer full of document to the parser</dd> |
| </dl> |
| |
| <p>These functions and others are described in the <a |
| href="#reference">reference</a> part of this document. The reference |
| section also describes in detail the parameters passed to the |
| different types of handlers.</p> |
| |
| <p>Let's look at a very simple example program that only uses 3 of the |
| above functions (it doesn't need to set a character handler.) The |
| program <a href="../examples/outline.c">outline.c</a> prints an |
| element outline, indenting child elements to distinguish them from the |
| parent element that contains them. The start handler does all the |
| work. It prints two indenting spaces for every level of ancestor |
| elements, then it prints the element and attribute |
| information. Finally it increments the global <code>Depth</code> |
| variable.</p> |
| |
| <pre class="eg"> |
| int Depth; |
| |
| void XMLCALL |
| start(void *data, const char *el, const char **attr) { |
| int i; |
| |
| for (i = 0; i < Depth; i++) |
| printf(" "); |
| |
| printf("%s", el); |
| |
| for (i = 0; attr[i]; i += 2) { |
| printf(" %s='%s'", attr[i], attr[i + 1]); |
| } |
| |
| printf("\n"); |
| Depth++; |
| } /* End of start handler */ |
| </pre> |
| |
| <p>The end tag simply does the bookkeeping work of decrementing |
| <code>Depth</code>.</p> |
| <pre class="eg"> |
| void XMLCALL |
| end(void *data, const char *el) { |
| Depth--; |
| } /* End of end handler */ |
| </pre> |
| |
| <p>Note the <code>XMLCALL</code> annotation used for the callbacks. |
| This is used to ensure that the Expat and the callbacks are using the |
| same calling convention in case the compiler options used for Expat |
| itself and the client code are different. Expat tries not to care |
| what the default calling convention is, though it may require that it |
| be compiled with a default convention of "cdecl" on some platforms. |
| For code which uses Expat, however, the calling convention is |
| specified by the <code>XMLCALL</code> annotation on most platforms; |
| callbacks should be defined using this annotation.</p> |
| |
| <p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but |
| existing working Expat applications don't need to add it (since they |
| are already using the "cdecl" calling convention, or they wouldn't be |
| working). The annotation is only needed if the default calling |
| convention may be something other than "cdecl". To use the annotation |
| safely with older versions of Expat, you can conditionally define it |
| <em>after</em> including Expat's header file:</p> |
| |
| <pre class="eg"> |
| #include <expat.h> |
| |
| #ifndef XMLCALL |
| #if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) |
| #define XMLCALL __cdecl |
| #elif defined(__GNUC__) |
| #define XMLCALL __attribute__((cdecl)) |
| #else |
| #define XMLCALL |
| #endif |
| #endif |
| </pre> |
| |
| <p>After creating the parser, the main program just has the job of |
| shoveling the document to the parser so that it can do its work.</p> |
| |
| <hr /> |
| <h2><a name="building">Building and Installing Expat</a></h2> |
| |
| <p>The Expat distribution comes as a compressed (with GNU gzip) tar |
| file. You may download the latest version from <a href= |
| "http://sourceforge.net/projects/expat/" >Source Forge</a>. After |
| unpacking this, cd into the directory. Then follow either the Win32 |
| directions or Unix directions below.</p> |
| |
| <h3>Building under Win32</h3> |
| |
| <p>If you're using the GNU compiler under cygwin, follow the Unix |
| directions in the next section. Otherwise if you have Microsoft's |
| Developer Studio installed, |
| you can use CMake to generate a <code>.sln</code> file, e.g. |
| <code> |
| cmake -G"Visual Studio 15 2017" -DCMAKE_BUILD_TYPE=RelWithDebInfo . |
| </code>, and build Expat using <code>msbuild /m expat.sln</code> after.</p> |
| |
| <p>Alternatively, you may download the Win32 binary package that |
| contains the "expat.h" include file and a pre-built DLL.</p> |
| |
| <h3>Building under Unix (or GNU)</h3> |
| |
| <p>First you'll need to run the configure shell script in order to |
| configure the Makefiles and headers for your system.</p> |
| |
| <p>If you're happy with all the defaults that configure picks for you, |
| and you have permission on your system to install into /usr/local, you |
| can install Expat with this sequence of commands:</p> |
| |
| <pre class="eg"> |
| ./configure |
| make |
| make install |
| </pre> |
| |
| <p>There are some options that you can provide to this script, but the |
| only one we'll mention here is the <code>--prefix</code> option. You |
| can find out all the options available by running configure with just |
| the <code>--help</code> option.</p> |
| |
| <p>By default, the configure script sets things up so that the library |
| gets installed in <code>/usr/local/lib</code> and the associated |
| header file in <code>/usr/local/include</code>. But if you were to |
| give the option, <code>--prefix=/home/me/mystuff</code>, then the |
| library and header would get installed in |
| <code>/home/me/mystuff/lib</code> and |
| <code>/home/me/mystuff/include</code> respectively.</p> |
| |
| <h3>Configuring Expat Using the Pre-Processor</h3> |
| |
| <p>Expat's feature set can be configured using a small number of |
| pre-processor definitions. The definition of this symbols does not |
| affect the set of entry points for Expat, only the behavior of the API |
| and the definition of character types in the case of |
| <code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> |
| |
| <dl class="cpp-symbols"> |
| <dt>XML_DTD</dt> |
| <dd>Include support for using and reporting DTD-based content. If |
| this is defined, default attribute values from an external DTD subset |
| are reported and attribute value normalization occurs based on the |
| type of attributes defined in the external subset. Without |
| this, Expat has a smaller memory footprint and can be faster, but will |
| not load external entities or process conditional sections. This does |
| not affect the set of functions available in the API.</dd> |
| |
| <dt>XML_NS</dt> |
| <dd>When defined, support for the <cite><a href= |
| "http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> |
| specification is included.</dd> |
| |
| <dt>XML_UNICODE</dt> |
| <dd>When defined, character data reported to the application is |
| encoded in UTF-16 using wide characters of the type |
| <code>XML_Char</code>. This is implied if |
| <code>XML_UNICODE_WCHAR_T</code> is defined.</dd> |
| |
| <dt>XML_UNICODE_WCHAR_T</dt> |
| <dd>If defined, causes the <code>XML_Char</code> character type to be |
| defined using the <code>wchar_t</code> type; otherwise, <code>unsigned |
| short</code> is used. Defining this implies |
| <code>XML_UNICODE</code>.</dd> |
| |
| <dt>XML_LARGE_SIZE</dt> |
| <dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> |
| integer types to be at least 64 bits in size. This is intended to support |
| processing of very large input streams, where the return values of |
| <code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, |
| <code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and |
| <code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> |
| could overflow. It may not be supported by all compilers, and is turned |
| off by default.</dd> |
| |
| <dt>XML_CONTEXT_BYTES</dt> |
| <dd>The number of input bytes of markup context which the parser will |
| ensure are available for reporting via <code><a href= |
| "#XML_GetInputContext" >XML_GetInputContext</a></code>. This is |
| normally set to 1024, and must be set to a positive integer. If this |
| is not defined, the input context will not be available and <code><a |
| href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will |
| always report NULL. Without this, Expat has a smaller memory |
| footprint and can be faster.</dd> |
| |
| <dt>XML_STATIC</dt> |
| <dd>On Windows, this should be set if Expat is going to be linked |
| statically with the code that calls it; this is required to get all |
| the right MSVC magic annotations correct. This is ignored on other |
| platforms.</dd> |
| |
| <dt>XML_ATTR_INFO</dt> |
| <dd>If defined, makes the additional function <code><a href= |
| "#XML_GetAttributeInfo" >XML_GetAttributeInfo</a></code> available |
| for reporting attribute byte offsets.</dd> |
| </dl> |
| |
| <hr /> |
| <h2><a name="using">Using Expat</a></h2> |
| |
| <h3>Compiling and Linking Against Expat</h3> |
| |
| <p>Unless you installed Expat in a location not expected by your |
| compiler and linker, all you have to do to use Expat in your programs |
| is to include the Expat header (<code>#include <expat.h></code>) |
| in your files that make calls to it and to tell the linker that it |
| needs to link against the Expat library. On Unix systems, this would |
| usually be done with the <code>-lexpat</code> argument. Otherwise, |
| you'll need to tell the compiler where to look for the Expat header |
| and the linker where to find the Expat library. You may also need to |
| take steps to tell the operating system where to find this library at |
| run time.</p> |
| |
| <p>On a Unix-based system, here's what a Makefile might look like when |
| Expat is installed in a standard location:</p> |
| |
| <pre class="eg"> |
| CC=cc |
| LDFLAGS= |
| LIBS= -lexpat |
| xmlapp: xmlapp.o |
| $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) |
| </pre> |
| |
| <p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then |
| the Makefile would look like this:</p> |
| |
| <pre class="eg"> |
| CC=cc |
| CFLAGS= -I/home/me/mystuff/include |
| LDFLAGS= |
| LIBS= -L/home/me/mystuff/lib -lexpat |
| xmlapp: xmlapp.o |
| $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) |
| </pre> |
| |
| <p>You'd also have to set the environment variable |
| <code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or |
| to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if |
| LD_LIBRARY_PATH already has some directories in it) in order to run |
| your application.</p> |
| |
| <h3>Expat Basics</h3> |
| |
| <p>As we saw in the example in the overview, the first step in parsing |
| an XML document with Expat is to create a parser object. There are <a |
| href="#creation">three functions</a> in the Expat API for creating a |
| parser object. However, only two of these (<code><a href= |
| "#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= |
| "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for |
| constructing a parser for a top-level document. The object returned |
| by these functions is an opaque pointer (i.e. "expat.h" declares it as |
| void *) to data with further internal structure. In order to free the |
| memory associated with this object you must call <code><a href= |
| "#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have |
| provided any <a href="#userdata">user data</a> that gets stored in the |
| parser, then your application is responsible for freeing it prior to |
| calling <code>XML_ParserFree</code>.</p> |
| |
| <p>The objects returned by the parser creation functions are good for |
| parsing only one XML document or external parsed entity. If your |
| application needs to parse many XML documents, then it needs to create |
| a parser object for each one. The best way to deal with this is to |
| create a higher level object that contains all the default |
| initialization you want for your parser objects.</p> |
| |
| <p>Walking through a document hierarchy with a stream oriented parser |
| will require a good stack mechanism in order to keep track of current |
| context. For instance, to answer the simple question, "What element |
| does this text belong to?" requires a stack, since the parser may have |
| descended into other elements that are children of the current one and |
| has encountered this text on the way out.</p> |
| |
| <p>The things you're likely to want to keep on a stack are the |
| currently opened element and it's attributes. You push this |
| information onto the stack in the start handler and you pop it off in |
| the end handler.</p> |
| |
| <p>For some tasks, it is sufficient to just keep information on what |
| the depth of the stack is (or would be if you had one.) The outline |
| program shown above presents one example. Another such task would be |
| skipping over a complete element. When you see the start tag for the |
| element you want to skip, you set a skip flag and record the depth at |
| which the element started. When the end tag handler encounters the |
| same depth, the skipped element has ended and the flag may be |
| cleared. If you follow the convention that the root element starts at |
| 1, then you can use the same variable for skip flag and skip |
| depth.</p> |
| |
| <pre class="eg"> |
| void |
| init_info(Parseinfo *info) { |
| info->skip = 0; |
| info->depth = 1; |
| /* Other initializations here */ |
| } /* End of init_info */ |
| |
| void XMLCALL |
| rawstart(void *data, const char *el, const char **attr) { |
| Parseinfo *inf = (Parseinfo *) data; |
| |
| if (! inf->skip) { |
| if (should_skip(inf, el, attr)) { |
| inf->skip = inf->depth; |
| } |
| else |
| start(inf, el, attr); /* This does rest of start handling */ |
| } |
| |
| inf->depth++; |
| } /* End of rawstart */ |
| |
| void XMLCALL |
| rawend(void *data, const char *el) { |
| Parseinfo *inf = (Parseinfo *) data; |
| |
| inf->depth--; |
| |
| if (! inf->skip) |
| end(inf, el); /* This does rest of end handling */ |
| |
| if (inf->skip == inf->depth) |
| inf->skip = 0; |
| } /* End rawend */ |
| </pre> |
| |
| <p>Notice in the above example the difference in how depth is |
| manipulated in the start and end handlers. The end tag handler should |
| be the mirror image of the start tag handler. This is necessary to |
| properly model containment. Since, in the start tag handler, we |
| incremented depth <em>after</em> the main body of start tag code, then |
| in the end handler, we need to manipulate it <em>before</em> the main |
| body. If we'd decided to increment it first thing in the start |
| handler, then we'd have had to decrement it last thing in the end |
| handler.</p> |
| |
| <h3 id="userdata">Communicating between handlers</h3> |
| |
| <p>In order to be able to pass information between different handlers |
| without using globals, you'll need to define a data structure to hold |
| the shared variables. You can then tell Expat (with the <code><a href= |
| "#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a |
| pointer to this structure to the handlers. This is the first |
| argument received by most handlers. In the <a href="#reference" |
| >reference section</a>, an argument to a callback function is named |
| <code>userData</code> and have type <code>void *</code> if the user |
| data is passed; it will have the type <code>XML_Parser</code> if the |
| parser itself is passed. When the parser is passed, the user data may |
| be retrieved using <code><a href="#XML_GetUserData" |
| >XML_GetUserData</a></code>.</p> |
| |
| <p>One common case where multiple calls to a single handler may need |
| to communicate using an application data structure is the case when |
| content passed to the character data handler (set by <code><a href= |
| "#XML_SetCharacterDataHandler" |
| >XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A |
| common first-time mistake with any of the event-oriented interfaces to |
| an XML parser is to expect all the text contained in an element to be |
| reported by a single call to the character data handler. Expat, like |
| many other XML parsers, reports such data as a sequence of calls; |
| there's no way to know when the end of the sequence is reached until a |
| different callback is made. A buffer referenced by the user data |
| structure proves both an effective and convenient place to accumulate |
| character data.</p> |
| |
| <!-- XXX example needed here --> |
| |
| |
| <h3>XML Version</h3> |
| |
| <p>Expat is an XML 1.0 parser, and as such never complains based on |
| the value of the <code>version</code> pseudo-attribute in the XML |
| declaration, if present.</p> |
| |
| <p>If an application needs to check the version number (to support |
| alternate processing), it should use the <code><a href= |
| "#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to |
| set a handler that uses the information in the XML declaration to |
| determine what to do. This example shows how to check that only a |
| version number of <code>"1.0"</code> is accepted:</p> |
| |
| <pre class="eg"> |
| static int wrong_version; |
| static XML_Parser parser; |
| |
| static void XMLCALL |
| xmldecl_handler(void *userData, |
| const XML_Char *version, |
| const XML_Char *encoding, |
| int standalone) |
| { |
| static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; |
| |
| int i; |
| |
| for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { |
| if (version[i] != Version_1_0[i]) { |
| wrong_version = 1; |
| /* also clear all other handlers: */ |
| XML_SetCharacterDataHandler(parser, NULL); |
| ... |
| return; |
| } |
| } |
| ... |
| } |
| </pre> |
| |
| <h3>Namespace Processing</h3> |
| |
| <p>When the parser is created using the <code><a href= |
| "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat |
| performs namespace processing. Under namespace processing, Expat |
| consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, |
| which declare namespaces for the scope of the element in which they |
| occur. This means that your start handler will not see these |
| attributes. Your application can still be informed of these |
| declarations by setting namespace declaration handlers with <a href= |
| "#XML_SetNamespaceDeclHandler" |
| ><code>XML_SetNamespaceDeclHandler</code></a>.</p> |
| |
| <p>Element type and attribute names that belong to a given namespace |
| are passed to the appropriate handler in expanded form. By default |
| this expanded form is a concatenation of the namespace URI, the |
| separator character (which is the 2nd argument to <code><a href= |
| "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local |
| name (i.e. the part after the colon). Names with undeclared prefixes |
| are not well-formed when namespace processing is enabled, and will |
| trigger an error. Unprefixed attribute names are never expanded, |
| and unprefixed element names are only expanded when they are in the |
| scope of a default namespace.</p> |
| |
| <p>However if <code><a href= "#XML_SetReturnNSTriplet" |
| >XML_SetReturnNSTriplet</a></code> has been called with a non-zero |
| <code>do_nst</code> parameter, then the expanded form for names with |
| an explicit prefix is a concatenation of: URI, separator, local name, |
| separator, prefix.</p> |
| |
| <p>You can set handlers for the start of a namespace declaration and |
| for the end of a scope of a declaration with the <code><a href= |
| "#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> |
| function. The StartNamespaceDeclHandler is called prior to the start |
| tag handler and the EndNamespaceDeclHandler is called after the |
| corresponding end tag that ends the namespace's scope. The namespace |
| start handler gets passed the prefix and URI for the namespace. For a |
| default namespace declaration (xmlns='...'), the prefix will be null. |
| The URI will be null for the case where the default namespace is being |
| unset. The namespace end handler just gets the prefix for the closing |
| scope.</p> |
| |
| <p>These handlers are called for each declaration. So if, for |
| instance, a start tag had three namespace declarations, then the |
| StartNamespaceDeclHandler would be called three times before the start |
| tag handler is called, once for each declaration.</p> |
| |
| <h3>Character Encodings</h3> |
| |
| <p>While XML is based on Unicode, and every XML processor is required |
| to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), |
| other encodings may be declared in XML documents or entities. For the |
| main document, an XML declaration may contain an encoding |
| declaration:</p> |
| <pre> |
| <?xml version="1.0" encoding="ISO-8859-2"?> |
| </pre> |
| |
| <p>External parsed entities may begin with a text declaration, which |
| looks like an XML declaration with just an encoding declaration:</p> |
| <pre> |
| <?xml encoding="Big5"?> |
| </pre> |
| |
| <p>With Expat, you may also specify an encoding at the time of |
| creating a parser. This is useful when the encoding information may |
| come from a source outside the document itself (like a higher level |
| protocol.)</p> |
| |
| <p><a name="builtin_encodings"></a>There are four built-in encodings |
| in Expat:</p> |
| <ul> |
| <li>UTF-8</li> |
| <li>UTF-16</li> |
| <li>ISO-8859-1</li> |
| <li>US-ASCII</li> |
| </ul> |
| |
| <p>Anything else discovered in an encoding declaration or in the |
| protocol encoding specified in the parser constructor, triggers a call |
| to the <code>UnknownEncodingHandler</code>. This handler gets passed |
| the encoding name and a pointer to an <code>XML_Encoding</code> data |
| structure. Your handler must fill in this structure and return |
| <code>XML_STATUS_OK</code> if it knows how to deal with the |
| encoding. Otherwise the handler should return |
| <code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer |
| to an optional application data structure that you may indicate when |
| you set the handler.</p> |
| |
| <p>Expat places restrictions on character encodings that it can |
| support by filling in the <code>XML_Encoding</code> structure. |
| include file:</p> |
| <ol> |
| <li>Every ASCII character that can appear in a well-formed XML document |
| must be represented by a single byte, and that byte must correspond to |
| it's ASCII encoding (except for the characters $@\^'{}~)</li> |
| <li>Characters must be encoded in 4 bytes or less.</li> |
| <li>All characters encoded must have Unicode scalar values less than or |
| equal to 65535 (0xFFFF)<em>This does not apply to the built-in support |
| for UTF-16 and UTF-8</em></li> |
| <li>No character may be encoded by more that one distinct sequence of |
| bytes</li> |
| </ol> |
| |
| <p><code>XML_Encoding</code> contains an array of integers that |
| correspond to the 1st byte of an encoding sequence. If the value in |
| the array for a byte is zero or positive, then the byte is a single |
| byte encoding that encodes the Unicode scalar value contained in the |
| array. A -1 in this array indicates a malformed byte. If the value is |
| -2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte |
| sequence respectively. Multi-byte sequences are sent to the convert |
| function pointed at in the <code>XML_Encoding</code> structure. This |
| function should return the Unicode scalar value for the sequence or -1 |
| if the sequence is malformed.</p> |
| |
| <p>One pitfall that novice Expat users are likely to fall into is that |
| although Expat may accept input in various encodings, the strings that |
| it passes to the handlers are always encoded in UTF-8 or UTF-16 |
| (depending on how Expat was compiled). Your application is responsible |
| for any translation of these strings into other encodings.</p> |
| |
| <h3>Handling External Entity References</h3> |
| |
| <p>Expat does not read or parse external entities directly. Note that |
| any external DTD is a special case of an external entity. If you've |
| set no <code>ExternalEntityRefHandler</code>, then external entity |
| references are silently ignored. Otherwise, it calls your handler with |
| the information needed to read and parse the external entity.</p> |
| |
| <p>Your handler isn't actually responsible for parsing the entity, but |
| it is responsible for creating a subsidiary parser with <code><a href= |
| "#XML_ExternalEntityParserCreate" |
| >XML_ExternalEntityParserCreate</a></code> that will do the job. This |
| returns an instance of <code>XML_Parser</code> that has handlers and |
| other data structures initialized from the parent parser. You may then |
| use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a |
| href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this |
| parser. Since external entities my refer to other external entities, |
| your handler should be prepared to be called recursively.</p> |
| |
| <h3>Parsing DTDs</h3> |
| |
| <p>In order to parse parameter entities, before starting the parse, |
| you must call <code><a href= "#XML_SetParamEntityParsing" |
| >XML_SetParamEntityParsing</a></code> with one of the following |
| arguments:</p> |
| <dl> |
| <dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> |
| <dd>Don't parse parameter entities or the external subset</dd> |
| <dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> |
| <dd>Parse parameter entities and the external subset unless |
| <code>standalone</code> was set to "yes" in the XML declaration.</dd> |
| <dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> |
| <dd>Always parse parameter entities and the external subset</dd> |
| </dl> |
| |
| <p>In order to read an external DTD, you also have to set an external |
| entity reference handler as described above.</p> |
| |
| <h3 id="stop-resume">Temporarily Stopping Parsing</h3> |
| |
| <p>Expat 1.95.8 introduces a new feature: its now possible to stop |
| parsing temporarily from within a handler function, even if more data |
| has already been passed into the parser. Applications for this |
| include</p> |
| |
| <ul> |
| <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" |
| >XInclude</a> specification.</li> |
| |
| <li>Delaying further processing until additional information is |
| available from some other source.</li> |
| |
| <li>Adjusting processor load as task priorities shift within an |
| application.</li> |
| |
| <li>Stopping parsing completely (simply free or reset the parser |
| instead of resuming in the outer parsing loop). This can be useful |
| if an application-domain error is found in the XML being parsed or if |
| the result of the parse is determined not to be useful after |
| all.</li> |
| </ul> |
| |
| <p>To take advantage of this feature, the main parsing loop of an |
| application needs to support this specifically. It cannot be |
| supported with a parsing loop compatible with Expat 1.95.7 or |
| earlier (though existing loops will continue to work without |
| supporting the stop/resume feature).</p> |
| |
| <p>An application that uses this feature for a single parser will have |
| the rough structure (in pseudo-code):</p> |
| |
| <pre class="pseudocode"> |
| fd = open_input() |
| p = create_parser() |
| |
| if parse_xml(p, fd) { |
| /* suspended */ |
| |
| int suspended = 1; |
| |
| while (suspended) { |
| do_something_else() |
| if ready_to_resume() { |
| suspended = continue_parsing(p, fd); |
| } |
| } |
| } |
| </pre> |
| |
| <p>An application that may resume any of several parsers based on |
| input (either from the XML being parsed or some other source) will |
| certainly have more interesting control structures.</p> |
| |
| <p>This C function could be used for the <code>parse_xml</code> |
| function mentioned in the pseudo-code above:</p> |
| |
| <pre class="eg"> |
| #define BUFF_SIZE 10240 |
| |
| /* Parse a document from the open file descriptor 'fd' until the parse |
| is complete (the document has been completely parsed, or there's |
| been an error), or the parse is stopped. Return non-zero when |
| the parse is merely suspended. |
| */ |
| int |
| parse_xml(XML_Parser p, int fd) |
| { |
| for (;;) { |
| int last_chunk; |
| int bytes_read; |
| enum XML_Status status; |
| |
| void *buff = XML_GetBuffer(p, BUFF_SIZE); |
| if (buff == NULL) { |
| /* handle error... */ |
| return 0; |
| } |
| bytes_read = read(fd, buff, BUFF_SIZE); |
| if (bytes_read < 0) { |
| /* handle error... */ |
| return 0; |
| } |
| status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); |
| switch (status) { |
| case XML_STATUS_ERROR: |
| /* handle error... */ |
| return 0; |
| case XML_STATUS_SUSPENDED: |
| return 1; |
| } |
| if (bytes_read == 0) |
| return 0; |
| } |
| } |
| </pre> |
| |
| <p>The corresponding <code>continue_parsing</code> function is |
| somewhat simpler, since it only need deal with the return code from |
| <code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can |
| delegate the input handling to the <code>parse_xml</code> |
| function:</p> |
| |
| <pre class="eg"> |
| /* Continue parsing a document which had been suspended. The 'p' and |
| 'fd' arguments are the same as passed to parse_xml(). Return |
| non-zero when the parse is suspended. |
| */ |
| int |
| continue_parsing(XML_Parser p, int fd) |
| { |
| enum XML_Status status = XML_ResumeParser(p); |
| switch (status) { |
| case XML_STATUS_ERROR: |
| /* handle error... */ |
| return 0; |
| case XML_ERROR_NOT_SUSPENDED: |
| /* handle error... */ |
| return 0;. |
| case XML_STATUS_SUSPENDED: |
| return 1; |
| } |
| return parse_xml(p, fd); |
| } |
| </pre> |
| |
| <p>Now that we've seen what a mess the top-level parsing loop can |
| become, what have we gained? Very simply, we can now use the <code><a |
| href= "#XML_StopParser" >XML_StopParser</a></code> function to stop |
| parsing, without having to go to great lengths to avoid additional |
| processing that we're expecting to ignore. As a bonus, we get to stop |
| parsing <em>temporarily</em>, and come back to it when we're |
| ready.</p> |
| |
| <p>To stop parsing from a handler function, use the <code><a href= |
| "#XML_StopParser" >XML_StopParser</a></code> function. This function |
| takes two arguments; the parser being stopped and a flag indicating |
| whether the parse can be resumed in the future.</p> |
| |
| <!-- XXX really need more here --> |
| |
| |
| <hr /> |
| <!-- ================================================================ --> |
| |
| <h2><a name="reference">Expat Reference</a></h2> |
| |
| <h3><a name="creation">Parser Creation</a></h3> |
| |
| <h4 id="XML_ParserCreate">XML_ParserCreate</h4> |
| <pre class="fcndec"> |
| XML_Parser XMLCALL |
| XML_ParserCreate(const XML_Char *encoding); |
| </pre> |
| <div class="fcndef"> |
| Construct a new parser. If encoding is non-null, it specifies a |
| character encoding to use for the document. This overrides the document |
| encoding declaration. There are four built-in encodings: |
| <ul> |
| <li>US-ASCII</li> |
| <li>UTF-8</li> |
| <li>UTF-16</li> |
| <li>ISO-8859-1</li> |
| </ul> |
| Any other value will invoke a call to the UnknownEncodingHandler. |
| </div> |
| |
| <h4 id="XML_ParserCreateNS">XML_ParserCreateNS</h4> |
| <pre class="fcndec"> |
| XML_Parser XMLCALL |
| XML_ParserCreateNS(const XML_Char *encoding, |
| XML_Char sep); |
| </pre> |
| <div class="fcndef"> |
| Constructs a new parser that has namespace processing in effect. Namespace |
| expanded element names and attribute names are returned as a concatenation |
| of the namespace URI, <em>sep</em>, and the local part of the name. This |
| means that you should pick a character for <em>sep</em> that can't be part |
| of an URI. Since Expat does not check namespace URIs for conformance, the |
| only safe choice for a namespace separator is a character that is illegal |
| in XML. For instance, <code>'\xFF'</code> is not legal in UTF-8, and |
| <code>'\xFFFF'</code> is not legal in UTF-16. There is a special case when |
| <em>sep</em> is the null character <code>'\0'</code>: the namespace URI and |
| the local part will be concatenated without any separator - this is intended |
| to support RDF processors. It is a programming error to use the null separator |
| with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> |
| |
| <p><strong>Note:</strong> |
| Expat does not validate namespace URIs (beyond encoding) |
| against RFC 3986 today (and is not required to do so with regard to |
| the XML 1.0 namespaces specification) but it may start doing that |
| in future releases. Before that, an application using Expat must |
| be ready to receive namespace URIs containing non-URI characters. |
| </p> |
| |
| <h4 id="XML_ParserCreate_MM">XML_ParserCreate_MM</h4> |
| <pre class="fcndec"> |
| XML_Parser XMLCALL |
| XML_ParserCreate_MM(const XML_Char *encoding, |
| const XML_Memory_Handling_Suite *ms, |
| const XML_Char *sep); |
| </pre> |
| <pre class="signature"> |
| typedef struct { |
| void *(XMLCALL *malloc_fcn)(size_t size); |
| void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); |
| void (XMLCALL *free_fcn)(void *ptr); |
| } XML_Memory_Handling_Suite; |
| </pre> |
| <div class="fcndef"> |
| <p>Construct a new parser using the suite of memory handling functions |
| specified in <code>ms</code>. If <code>ms</code> is NULL, then use the |
| standard set of memory management functions. If <code>sep</code> is |
| non NULL, then namespace processing is enabled in the created parser |
| and the character pointed at by sep is used as the separator between |
| the namespace URI and the local part of the name.</p> |
| </div> |
| |
| <h4 id="XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</h4> |
| <pre class="fcndec"> |
| XML_Parser XMLCALL |
| XML_ExternalEntityParserCreate(XML_Parser p, |
| const XML_Char *context, |
| const XML_Char *encoding); |
| </pre> |
| <div class="fcndef"> |
| Construct a new <code>XML_Parser</code> object for parsing an external |
| general entity. Context is the context argument passed in a call to a |
| ExternalEntityRefHandler. Other state information such as handlers, |
| user data, namespace processing is inherited from the parser passed as |
| the 1st argument. So you shouldn't need to call any of the behavior |
| changing functions on this parser (unless you want it to act |
| differently than the parent parser). |
| </div> |
| |
| <h4 id="XML_ParserFree">XML_ParserFree</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_ParserFree(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Free memory used by the parser. Your application is responsible for |
| freeing any memory associated with <a href="#userdata">user data</a>. |
| </div> |
| |
| <h4 id="XML_ParserReset">XML_ParserReset</h4> |
| <pre class="fcndec"> |
| XML_Bool XMLCALL |
| XML_ParserReset(XML_Parser p, |
| const XML_Char *encoding); |
| </pre> |
| <div class="fcndef"> |
| Clean up the memory structures maintained by the parser so that it may |
| be used again. After this has been called, <code>parser</code> is |
| ready to start parsing a new document. All handlers are cleared from |
| the parser, except for the unknownEncodingHandler. The parser's external |
| state is re-initialized except for the values of ns and ns_triplets. |
| This function may not be used on a parser created using <code><a href= |
| "#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a |
| ></code>; it will return <code>XML_FALSE</code> in that case. Returns |
| <code>XML_TRUE</code> on success. Your application is responsible for |
| dealing with any memory associated with <a href="#userdata">user data</a>. |
| </div> |
| |
| <h3><a name="parsing">Parsing</a></h3> |
| |
| <p>To state the obvious: the three parsing functions <code><a href= |
| "#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> |
| XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> |
| XML_GetBuffer</a></code> must not be called from within a handler |
| unless they operate on a separate parser instance, that is, one that |
| did not call the handler. For example, it is OK to call the parsing |
| functions from within an <code>XML_ExternalEntityRefHandler</code>, |
| if they apply to the parser created by |
| <code><a href= "#XML_ExternalEntityParserCreate" |
| >XML_ExternalEntityParserCreate</a></code>.</p> |
| |
| <p>Note: The <code>len</code> argument passed to these functions |
| should be considerably less than the maximum value for an integer, |
| as it could create an integer overflow situation if the added |
| lengths of a buffer and the unprocessed portion of the previous buffer |
| exceed the maximum integer value. Input data at the end of a buffer |
| will remain unprocessed if it is part of an XML token for which the |
| end is not part of that buffer.</p> |
| |
| <h4 id="XML_Parse">XML_Parse</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_Parse(XML_Parser p, |
| const char *s, |
| int len, |
| int isFinal); |
| </pre> |
| <pre class="signature"> |
| enum XML_Status { |
| XML_STATUS_ERROR = 0, |
| XML_STATUS_OK = 1 |
| }; |
| </pre> |
| <div class="fcndef"> |
| Parse some more of the document. The string <code>s</code> is a buffer |
| containing part (or perhaps all) of the document. The number of bytes of s |
| that are part of the document is indicated by <code>len</code>. This means |
| that <code>s</code> doesn't have to be null terminated. It also means that |
| if <code>len</code> is larger than the number of bytes in the block of |
| memory that <code>s</code> points at, then a memory fault is likely. The |
| <code>isFinal</code> parameter informs the parser that this is the last |
| piece of the document. Frequently, the last piece is empty (i.e. |
| <code>len</code> is zero.) |
| If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. |
| Otherwise it returns <code>XML_STATUS_OK</code> value. |
| </div> |
| |
| <h4 id="XML_ParseBuffer">XML_ParseBuffer</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_ParseBuffer(XML_Parser p, |
| int len, |
| int isFinal); |
| </pre> |
| <div class="fcndef"> |
| This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, |
| except in this case Expat provides the buffer. By obtaining the |
| buffer from Expat with the <code><a href= "#XML_GetBuffer" |
| >XML_GetBuffer</a></code> function, the application can avoid double |
| copying of the input. |
| </div> |
| |
| <h4 id="XML_GetBuffer">XML_GetBuffer</h4> |
| <pre class="fcndec"> |
| void * XMLCALL |
| XML_GetBuffer(XML_Parser p, |
| int len); |
| </pre> |
| <div class="fcndef"> |
| Obtain a buffer of size <code>len</code> to read a piece of the document |
| into. A NULL value is returned if Expat can't allocate enough memory for |
| this buffer. A NULL value may also be returned if <code>len</code> is zero. |
| This has to be called prior to every call to |
| <code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A |
| typical use would look like this: |
| |
| <pre class="eg"> |
| for (;;) { |
| int bytes_read; |
| void *buff = XML_GetBuffer(p, BUFF_SIZE); |
| if (buff == NULL) { |
| /* handle error */ |
| } |
| |
| bytes_read = read(docfd, buff, BUFF_SIZE); |
| if (bytes_read < 0) { |
| /* handle error */ |
| } |
| |
| if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { |
| /* handle parse error */ |
| } |
| |
| if (bytes_read == 0) |
| break; |
| } |
| </pre> |
| </div> |
| |
| <h4 id="XML_StopParser">XML_StopParser</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_StopParser(XML_Parser p, |
| XML_Bool resumable); |
| </pre> |
| <div class="fcndef"> |
| |
| <p>Stops parsing, causing <code><a href= "#XML_Parse" |
| >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" |
| >XML_ParseBuffer</a></code> to return. Must be called from within a |
| call-back handler, except when aborting (when <code>resumable</code> |
| is <code>XML_FALSE</code>) an already suspended parser. Some |
| call-backs may still follow because they would otherwise get |
| lost, including</p> |
| <ul> |
| <li> the end element handler for empty elements when stopped in the |
| start element handler,</li> |
| <li> the end namespace declaration handler when stopped in the end |
| element handler,</li> |
| <li> the character data handler when stopped in the character data handler |
| while making multiple call-backs on a contiguous chunk of characters,</li> |
| </ul> |
| <p>and possibly others.</p> |
| |
| <p>This can be called from most handlers, including DTD related |
| call-backs, except when parsing an external parameter entity and |
| <code>resumable</code> is <code>XML_TRUE</code>. Returns |
| <code>XML_STATUS_OK</code> when successful, |
| <code>XML_STATUS_ERROR</code> otherwise. The possible error codes |
| are:</p> |
| <dl> |
| <dt><code>XML_ERROR_SUSPENDED</code></dt> |
| <dd>when suspending an already suspended parser.</dd> |
| <dt><code>XML_ERROR_FINISHED</code></dt> |
| <dd>when the parser has already finished.</dd> |
| <dt><code>XML_ERROR_SUSPEND_PE</code></dt> |
| <dd>when suspending while parsing an external PE.</dd> |
| </dl> |
| |
| <p>Since the stop/resume feature requires application support in the |
| outer parsing loop, it is an error to call this function for a parser |
| not being handled appropriately; see <a href= "#stop-resume" |
| >Temporarily Stopping Parsing</a> for more information.</p> |
| |
| <p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing |
| is <em>suspended</em>, that is, <code><a href= "#XML_Parse" |
| >XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" |
| >XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. |
| Otherwise, parsing is <em>aborted</em>, that is, <code><a href= |
| "#XML_Parse" >XML_Parse</a></code> and <code><a href= |
| "#XML_ParseBuffer" >XML_ParseBuffer</a></code> return |
| <code>XML_STATUS_ERROR</code> with error code |
| <code>XML_ERROR_ABORTED</code>.</p> |
| |
| <p><strong>Note:</strong> |
| This will be applied to the current parser instance only, that is, if |
| there is a parent parser then it will continue parsing when the |
| external entity reference handler returns. It is up to the |
| implementation of that handler to call <code><a href= |
| "#XML_StopParser" >XML_StopParser</a></code> on the parent parser |
| (recursively), if one wants to stop parsing altogether.</p> |
| |
| <p>When suspended, parsing can be resumed by calling <code><a href= |
| "#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> |
| |
| <p>New in Expat 1.95.8.</p> |
| </div> |
| |
| <h4 id="XML_ResumeParser">XML_ResumeParser</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_ResumeParser(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| <p>Resumes parsing after it has been suspended with <code><a href= |
| "#XML_StopParser" >XML_StopParser</a></code>. Must not be called from |
| within a handler call-back. Returns same status codes as <code><a |
| href= "#XML_Parse">XML_Parse</a></code> or <code><a href= |
| "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error |
| code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the |
| parser was not currently suspended.</p> |
| |
| <p><strong>Note:</strong> |
| This must be called on the most deeply nested child parser instance |
| first, and on its parent parser only after the child parser has |
| finished, to be applied recursively until the document entity's parser |
| is restarted. That is, the parent parser will not resume by itself |
| and it is up to the application to call <code><a href= |
| "#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the |
| appropriate moment.</p> |
| |
| <p>New in Expat 1.95.8.</p> |
| </div> |
| |
| <h4 id="XML_GetParsingStatus">XML_GetParsingStatus</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_GetParsingStatus(XML_Parser p, |
| XML_ParsingStatus *status); |
| </pre> |
| <pre class="signature"> |
| enum XML_Parsing { |
| XML_INITIALIZED, |
| XML_PARSING, |
| XML_FINISHED, |
| XML_SUSPENDED |
| }; |
| |
| typedef struct { |
| enum XML_Parsing parsing; |
| XML_Bool finalBuffer; |
| } XML_ParsingStatus; |
| </pre> |
| <div class="fcndef"> |
| <p>Returns status of parser with respect to being initialized, |
| parsing, finished, or suspended, and whether the final buffer is being |
| processed. The <code>status</code> parameter <em>must not</em> be |
| NULL.</p> |
| |
| <p>New in Expat 1.95.8.</p> |
| </div> |
| |
| |
| <h3><a name="setting">Handler Setting</a></h3> |
| |
| <p>Although handlers are typically set prior to parsing and left alone, an |
| application may choose to set or change the handler for a parsing event |
| while the parse is in progress. For instance, your application may choose |
| to ignore all text not descended from a <code>para</code> element. One |
| way it could do this is to set the character handler when a para start tag |
| is seen, and unset it for the corresponding end tag.</p> |
| |
| <p>A handler may be <em>unset</em> by providing a NULL pointer to the |
| appropriate handler setter. None of the handler setting functions have |
| a return value.</p> |
| |
| <p>Your handlers will be receiving strings in arrays of type |
| <code>XML_Char</code>. This type is conditionally defined in expat.h as |
| either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. |
| The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. |
| Note that you'll receive them in this form independent of the original |
| encoding of the document.</p> |
| |
| <div class="handler"> |
| <h4 id="XML_SetStartElementHandler">XML_SetStartElementHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetStartElementHandler(XML_Parser p, |
| XML_StartElementHandler start); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_StartElementHandler)(void *userData, |
| const XML_Char *name, |
| const XML_Char **atts); |
| </pre> |
| <p>Set handler for start (and empty) tags. Attributes are passed to the start |
| handler as a pointer to a vector of char pointers. Each attribute seen in |
| a start (or empty) tag occupies 2 consecutive places in this vector: the |
| attribute name followed by the attribute value. These pairs are terminated |
| by a null pointer.</p> |
| <p>Note that an empty tag generates a call to both start and end handlers |
| (in that order).</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetEndElementHandler">XML_SetEndElementHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetEndElementHandler(XML_Parser p, |
| XML_EndElementHandler); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_EndElementHandler)(void *userData, |
| const XML_Char *name); |
| </pre> |
| <p>Set handler for end (and empty) tags. As noted above, an empty tag |
| generates a call to both start and end handlers.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetElementHandler">XML_SetElementHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetElementHandler(XML_Parser p, |
| XML_StartElementHandler start, |
| XML_EndElementHandler end); |
| </pre> |
| <p>Set handlers for start and end tags with one call.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetCharacterDataHandler(XML_Parser p, |
| XML_CharacterDataHandler charhndl) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_CharacterDataHandler)(void *userData, |
| const XML_Char *s, |
| int len); |
| </pre> |
| <p>Set a text handler. The string your handler receives |
| is <em>NOT null-terminated</em>. You have to use the length argument |
| to deal with the end of the string. A single block of contiguous text |
| free of markup may still result in a sequence of calls to this handler. |
| In other words, if you're searching for a pattern in the text, it may |
| be split across calls to this handler. Note: Setting this handler to NULL |
| may <em>NOT immediately</em> terminate call-backs if the parser is currently |
| processing such a single block of contiguous markup-free text, as the parser |
| will continue calling back until the end of the block is reached.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetProcessingInstructionHandler(XML_Parser p, |
| XML_ProcessingInstructionHandler proc) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_ProcessingInstructionHandler)(void *userData, |
| const XML_Char *target, |
| const XML_Char *data); |
| |
| </pre> |
| <p>Set a handler for processing instructions. The target is the first word |
| in the processing instruction. The data is the rest of the characters in |
| it after skipping all whitespace after the initial word.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetCommentHandler">XML_SetCommentHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetCommentHandler(XML_Parser p, |
| XML_CommentHandler cmnt) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_CommentHandler)(void *userData, |
| const XML_Char *data); |
| </pre> |
| <p>Set a handler for comments. The data is all text inside the comment |
| delimiters.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetStartCdataSectionHandler(XML_Parser p, |
| XML_StartCdataSectionHandler start); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_StartCdataSectionHandler)(void *userData); |
| </pre> |
| <p>Set a handler that gets called at the beginning of a CDATA section.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetEndCdataSectionHandler(XML_Parser p, |
| XML_EndCdataSectionHandler end); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_EndCdataSectionHandler)(void *userData); |
| </pre> |
| <p>Set a handler that gets called at the end of a CDATA section.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetCdataSectionHandler(XML_Parser p, |
| XML_StartCdataSectionHandler start, |
| XML_EndCdataSectionHandler end) |
| </pre> |
| <p>Sets both CDATA section handlers with one call.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetDefaultHandler">XML_SetDefaultHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetDefaultHandler(XML_Parser p, |
| XML_DefaultHandler hndl) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_DefaultHandler)(void *userData, |
| const XML_Char *s, |
| int len); |
| </pre> |
| |
| <p>Sets a handler for any characters in the document which wouldn't |
| otherwise be handled. This includes both data for which no handlers |
| can be set (like some kinds of DTD declarations) and data which could |
| be reported but which currently has no handler set. The characters |
| are passed exactly as they were present in the XML document except |
| that they will be encoded in UTF-8 or UTF-16. Line boundaries are not |
| normalized. Note that a byte order mark character is not passed to the |
| default handler. There are no guarantees about how characters are |
| divided between calls to the default handler: for example, a comment |
| might be split between multiple calls. Setting the handler with |
| this call has the side effect of turning off expansion of references |
| to internally defined general entities. Instead these references are |
| passed to the default handler.</p> |
| |
| <p>See also <code><a |
| href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetDefaultHandlerExpand(XML_Parser p, |
| XML_DefaultHandler hndl) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_DefaultHandler)(void *userData, |
| const XML_Char *s, |
| int len); |
| </pre> |
| <p>This sets a default handler, but doesn't inhibit the expansion of |
| internal entity references. The entity reference will not be passed |
| to the default handler.</p> |
| |
| <p>See also <code><a |
| href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetExternalEntityRefHandler(XML_Parser p, |
| XML_ExternalEntityRefHandler hndl) |
| </pre> |
| <pre class="signature"> |
| typedef int |
| (XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, |
| const XML_Char *context, |
| const XML_Char *base, |
| const XML_Char *systemId, |
| const XML_Char *publicId); |
| </pre> |
| <p>Set an external entity reference handler. This handler is also |
| called for processing an external DTD subset if parameter entity parsing |
| is in effect. (See <a href="#XML_SetParamEntityParsing"> |
| <code>XML_SetParamEntityParsing</code></a>.)</p> |
| |
| <p>The <code>context</code> parameter specifies the parsing context in |
| the format expected by the <code>context</code> argument to <code><a |
| href="#XML_ExternalEntityParserCreate" |
| >XML_ExternalEntityParserCreate</a></code>. <code>code</code> is |
| valid only until the handler returns, so if the referenced entity is |
| to be parsed later, it must be copied. <code>context</code> is NULL |
| only when the entity is a parameter entity, which is how one can |
| differentiate between general and parameter entities.</p> |
| |
| <p>The <code>base</code> parameter is the base to use for relative |
| system identifiers. It is set by <code><a |
| href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The |
| <code>publicId</code> parameter is the public id given in the entity |
| declaration and may be NULL. <code>systemId</code> is the system |
| identifier specified in the entity declaration and is never NULL.</p> |
| |
| <p>There are a couple of ways in which this handler differs from |
| others. First, this handler returns a status indicator (an |
| integer). <code>XML_STATUS_OK</code> should be returned for successful |
| handling of the external entity reference. Returning |
| <code>XML_STATUS_ERROR</code> indicates failure, and causes the |
| calling parser to return an |
| <code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> |
| |
| <p>Second, instead of having the user data as its first argument, it |
| receives the parser that encountered the entity reference. This, along |
| with the context parameter, may be used as arguments to a call to |
| <code><a href= "#XML_ExternalEntityParserCreate" |
| >XML_ExternalEntityParserCreate</a></code>. Using the returned |
| parser, the body of the external entity can be recursively parsed.</p> |
| |
| <p>Since this handler may be called recursively, it should not be saving |
| information into global or static variables.</p> |
| </div> |
| |
| <h4 id="XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_SetExternalEntityRefHandlerArg(XML_Parser p, |
| void *arg) |
| </pre> |
| <div class="fcndef"> |
| <p>Set the argument passed to the ExternalEntityRefHandler. If |
| <code>arg</code> is not NULL, it is the new value passed to the |
| handler set using <code><a href="#XML_SetExternalEntityRefHandler" |
| >XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is |
| NULL, the argument passed to the handler function will be the parser |
| object itself.</p> |
| |
| <p><strong>Note:</strong> |
| The type of <code>arg</code> and the type of the first argument to the |
| ExternalEntityRefHandler do not match. This function takes a |
| <code>void *</code> to be passed to the handler, while the handler |
| accepts an <code>XML_Parser</code>. This is a historical accident, |
| but will not be corrected before Expat 2.0 (at the earliest) to avoid |
| causing compiler warnings for code that's known to work with this |
| API. It is the responsibility of the application code to know the |
| actual type of the argument passed to the handler and to manage it |
| properly.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetSkippedEntityHandler(XML_Parser p, |
| XML_SkippedEntityHandler handler) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_SkippedEntityHandler)(void *userData, |
| const XML_Char *entityName, |
| int is_parameter_entity); |
| </pre> |
| <p>Set a skipped entity handler. This is called in two situations:</p> |
| <ol> |
| <li>An entity reference is encountered for which no declaration |
| has been read <em>and</em> this is not an error.</li> |
| <li>An internal entity reference is read, but not expanded, because |
| <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> |
| has been called.</li> |
| </ol> |
| <p>The <code>is_parameter_entity</code> argument will be non-zero for |
| a parameter entity and zero for a general entity.</p> <p>Note: Skipped |
| parameter entities in declarations and skipped general entities in |
| attribute values cannot be reported, because the event would be out of |
| sync with the reporting of the declarations or attribute values</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetUnknownEncodingHandler(XML_Parser p, |
| XML_UnknownEncodingHandler enchandler, |
| void *encodingHandlerData) |
| </pre> |
| <pre class="signature"> |
| typedef int |
| (XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, |
| const XML_Char *name, |
| XML_Encoding *info); |
| |
| typedef struct { |
| int map[256]; |
| void *data; |
| int (XMLCALL *convert)(void *data, const char *s); |
| void (XMLCALL *release)(void *data); |
| } XML_Encoding; |
| </pre> |
| <p>Set a handler to deal with encodings other than the <a |
| href="#builtin_encodings">built in set</a>. This should be done before |
| <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= |
| "#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the |
| given parser.</p> <p>If the handler knows how to deal with an encoding |
| with the given name, it should fill in the <code>info</code> data |
| structure and return <code>XML_STATUS_OK</code>. Otherwise it |
| should return <code>XML_STATUS_ERROR</code>. The handler will be called |
| at most once per parsed (external) entity. The optional application |
| data pointer <code>encodingHandlerData</code> will be passed back to |
| the handler.</p> |
| |
| <p>The map array contains information for every possible leading |
| byte in a byte sequence. If the corresponding value is >= 0, then it's |
| a single byte sequence and the byte encodes that Unicode value. If the |
| value is -1, then that byte is invalid as the initial byte in a sequence. |
| If the value is -n, where n is an integer > 1, then n is the number of |
| bytes in the sequence and the actual conversion is accomplished by a |
| call to the function pointed at by convert. This function may return -1 |
| if the sequence itself is invalid. The convert pointer may be null if |
| there are only single byte codes. The data parameter passed to the convert |
| function is the data pointer from <code>XML_Encoding</code>. The |
| string s is <em>NOT</em> null-terminated and points at the sequence of |
| bytes to be converted.</p> |
| |
| <p>The function pointed at by <code>release</code> is called by the |
| parser when it is finished with the encoding. It may be NULL.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetStartNamespaceDeclHandler(XML_Parser p, |
| XML_StartNamespaceDeclHandler start); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, |
| const XML_Char *prefix, |
| const XML_Char *uri); |
| </pre> |
| <p>Set a handler to be called when a namespace is declared. Namespace |
| declarations occur inside start tags. But the namespace declaration start |
| handler is called before the start tag handler for each namespace declared |
| in that start tag.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetEndNamespaceDeclHandler(XML_Parser p, |
| XML_EndNamespaceDeclHandler end); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, |
| const XML_Char *prefix); |
| </pre> |
| <p>Set a handler to be called when leaving the scope of a namespace |
| declaration. This will be called, for each namespace declaration, |
| after the handler for the end tag of the element in which the |
| namespace was declared.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetNamespaceDeclHandler(XML_Parser p, |
| XML_StartNamespaceDeclHandler start, |
| XML_EndNamespaceDeclHandler end) |
| </pre> |
| <p>Sets both namespace declaration handlers with a single call.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetXmlDeclHandler(XML_Parser p, |
| XML_XmlDeclHandler xmldecl); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_XmlDeclHandler)(void *userData, |
| const XML_Char *version, |
| const XML_Char *encoding, |
| int standalone); |
| </pre> |
| <p>Sets a handler that is called for XML declarations and also for |
| text declarations discovered in external entities. The way to |
| distinguish is that the <code>version</code> parameter will be NULL |
| for text declarations. The <code>encoding</code> parameter may be NULL |
| for an XML declaration. The <code>standalone</code> argument will |
| contain -1, 0, or 1 indicating respectively that there was no |
| standalone parameter in the declaration, that it was given as no, or |
| that it was given as yes.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetStartDoctypeDeclHandler(XML_Parser p, |
| XML_StartDoctypeDeclHandler start); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, |
| const XML_Char *doctypeName, |
| const XML_Char *sysid, |
| const XML_Char *pubid, |
| int has_internal_subset); |
| </pre> |
| <p>Set a handler that is called at the start of a DOCTYPE declaration, |
| before any external or internal subset is parsed. Both <code>sysid</code> |
| and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> |
| will be non-zero if the DOCTYPE declaration has an internal subset.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetEndDoctypeDeclHandler(XML_Parser p, |
| XML_EndDoctypeDeclHandler end); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); |
| </pre> |
| <p>Set a handler that is called at the end of a DOCTYPE declaration, |
| after parsing any external subset.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetDoctypeDeclHandler(XML_Parser p, |
| XML_StartDoctypeDeclHandler start, |
| XML_EndDoctypeDeclHandler end); |
| </pre> |
| <p>Set both doctype handlers with one call.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetElementDeclHandler">XML_SetElementDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetElementDeclHandler(XML_Parser p, |
| XML_ElementDeclHandler eldecl); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_ElementDeclHandler)(void *userData, |
| const XML_Char *name, |
| XML_Content *model); |
| </pre> |
| <pre class="signature"> |
| enum XML_Content_Type { |
| XML_CTYPE_EMPTY = 1, |
| XML_CTYPE_ANY, |
| XML_CTYPE_MIXED, |
| XML_CTYPE_NAME, |
| XML_CTYPE_CHOICE, |
| XML_CTYPE_SEQ |
| }; |
| |
| enum XML_Content_Quant { |
| XML_CQUANT_NONE, |
| XML_CQUANT_OPT, |
| XML_CQUANT_REP, |
| XML_CQUANT_PLUS |
| }; |
| |
| typedef struct XML_cp XML_Content; |
| |
| struct XML_cp { |
| enum XML_Content_Type type; |
| enum XML_Content_Quant quant; |
| const XML_Char * name; |
| unsigned int numchildren; |
| XML_Content * children; |
| }; |
| </pre> |
| <p>Sets a handler for element declarations in a DTD. The handler gets |
| called with the name of the element in the declaration and a pointer |
| to a structure that contains the element model. It's the user code's |
| responsibility to free model when finished with it. See <code> |
| <a href="#XML_FreeContentModel">XML_FreeContentModel</a></code>. |
| There is no need to free the model from the handler, it can be kept |
| around and freed at a later stage.</p> |
| |
| <p>The <code>model</code> argument is the root of a tree of |
| <code>XML_Content</code> nodes. If <code>type</code> equals |
| <code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then |
| <code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other |
| fields will be zero or NULL. If <code>type</code> is |
| <code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be |
| <code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and |
| <code>numchildren</code> will contain the number of elements that are |
| allowed to be mixed in and <code>children</code> points to an array of |
| <code>XML_Content</code> structures that will all have type |
| XML_CTYPE_NAME with no quantification. Only the root node can be type |
| <code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or |
| <code>XML_CTYPE_MIXED</code>.</p> |
| |
| <p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field |
| points to the name and the <code>numchildren</code> and |
| <code>children</code> fields will be zero and NULL. The |
| <code>quant</code> field will indicate any quantifiers placed on the |
| name.</p> |
| |
| <p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> |
| indicate a choice or sequence respectively. The |
| <code>numchildren</code> field indicates how many nodes in the choice |
| or sequence and <code>children</code> points to the nodes.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetAttlistDeclHandler(XML_Parser p, |
| XML_AttlistDeclHandler attdecl); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_AttlistDeclHandler)(void *userData, |
| const XML_Char *elname, |
| const XML_Char *attname, |
| const XML_Char *att_type, |
| const XML_Char *dflt, |
| int isrequired); |
| </pre> |
| <p>Set a handler for attlist declarations in the DTD. This handler is |
| called for <em>each</em> attribute. So a single attlist declaration |
| with multiple attributes declared will generate multiple calls to this |
| handler. The <code>elname</code> parameter returns the name of the |
| element for which the attribute is being declared. The attribute name |
| is in the <code>attname</code> parameter. The attribute type is in the |
| <code>att_type</code> parameter. It is the string representing the |
| type in the declaration with whitespace removed.</p> |
| |
| <p>The <code>dflt</code> parameter holds the default value. It will be |
| NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can |
| distinguish these two cases by checking the <code>isrequired</code> |
| parameter, which will be true in the case of "#REQUIRED" attributes. |
| Attributes which are "#FIXED" will have also have a true |
| <code>isrequired</code>, but they will have the non-NULL fixed value |
| in the <code>dflt</code> parameter.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetEntityDeclHandler(XML_Parser p, |
| XML_EntityDeclHandler handler); |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_EntityDeclHandler)(void *userData, |
| const XML_Char *entityName, |
| int is_parameter_entity, |
| const XML_Char *value, |
| int value_length, |
| const XML_Char *base, |
| const XML_Char *systemId, |
| const XML_Char *publicId, |
| const XML_Char *notationName); |
| </pre> |
| <p>Sets a handler that will be called for all entity declarations. |
| The <code>is_parameter_entity</code> argument will be non-zero in the |
| case of parameter entities and zero otherwise.</p> |
| |
| <p>For internal entities (<code><!ENTITY foo "bar"></code>), |
| <code>value</code> will be non-NULL and <code>systemId</code>, |
| <code>publicId</code>, and <code>notationName</code> will all be NULL. |
| The value string is <em>not</em> NULL terminated; the length is |
| provided in the <code>value_length</code> parameter. Do not use |
| <code>value_length</code> to test for internal entities, since it is |
| legal to have zero-length values. Instead check for whether or not |
| <code>value</code> is NULL.</p> <p>The <code>notationName</code> |
| argument will have a non-NULL value only for unparsed entity |
| declarations.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetUnparsedEntityDeclHandler(XML_Parser p, |
| XML_UnparsedEntityDeclHandler h) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, |
| const XML_Char *entityName, |
| const XML_Char *base, |
| const XML_Char *systemId, |
| const XML_Char *publicId, |
| const XML_Char *notationName); |
| </pre> |
| <p>Set a handler that receives declarations of unparsed entities. These |
| are entity declarations that have a notation (NDATA) field:</p> |
| |
| <div id="eg"><pre> |
| <!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> |
| </pre></div> |
| <p>This handler is obsolete and is provided for backwards |
| compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" |
| >XML_SetEntityDeclHandler</a>.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetNotationDeclHandler(XML_Parser p, |
| XML_NotationDeclHandler h) |
| </pre> |
| <pre class="signature"> |
| typedef void |
| (XMLCALL *XML_NotationDeclHandler)(void *userData, |
| const XML_Char *notationName, |
| const XML_Char *base, |
| const XML_Char *systemId, |
| const XML_Char *publicId); |
| </pre> |
| <p>Set a handler that receives notation declarations.</p> |
| </div> |
| |
| <div class="handler"> |
| <h4 id="XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</h4> |
| <pre class="setter"> |
| void XMLCALL |
| XML_SetNotStandaloneHandler(XML_Parser p, |
| XML_NotStandaloneHandler h) |
| </pre> |
| <pre class="signature"> |
| typedef int |
| (XMLCALL *XML_NotStandaloneHandler)(void *userData); |
| </pre> |
| <p>Set a handler that is called if the document is not "standalone". |
| This happens when there is an external subset or a reference to a |
| parameter entity, but does not have standalone set to "yes" in an XML |
| declaration. If this handler returns <code>XML_STATUS_ERROR</code>, |
| then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> |
| error.</p> |
| </div> |
| |
| <h3><a name="position">Parse position and error reporting functions</a></h3> |
| |
| <p>These are the functions you'll want to call when the parse |
| functions return <code>XML_STATUS_ERROR</code> (a parse error has |
| occurred), although the position reporting functions are useful outside |
| of errors. The position reported is the byte position (in the original |
| document or entity encoding) of the first of the sequence of |
| characters that generated the current event (or the error that caused |
| the parse functions to return <code>XML_STATUS_ERROR</code>.) The |
| exceptions are callbacks triggered by declarations in the document |
| prologue, in which case they exact position reported is somewhere in the |
| relevant markup, but not necessarily as meaningful as for other |
| events.</p> |
| |
| <p>The position reporting functions are accurate only outside of the |
| DTD. In other words, they usually return bogus information when |
| called from within a DTD declaration handler.</p> |
| |
| <h4 id="XML_GetErrorCode">XML_GetErrorCode</h4> |
| <pre class="fcndec"> |
| enum XML_Error XMLCALL |
| XML_GetErrorCode(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return what type of error has occurred. |
| </div> |
| |
| <h4 id="XML_ErrorString">XML_ErrorString</h4> |
| <pre class="fcndec"> |
| const XML_LChar * XMLCALL |
| XML_ErrorString(enum XML_Error code); |
| </pre> |
| <div class="fcndef"> |
| Return a string describing the error corresponding to code. |
| The code should be one of the enums that can be returned from |
| <code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. |
| </div> |
| |
| <h4 id="XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</h4> |
| <pre class="fcndec"> |
| XML_Index XMLCALL |
| XML_GetCurrentByteIndex(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return the byte offset of the position. This always corresponds to |
| the values returned by <code><a href= "#XML_GetCurrentLineNumber" |
| >XML_GetCurrentLineNumber</a></code> and <code><a href= |
| "#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. |
| </div> |
| |
| <h4 id="XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</h4> |
| <pre class="fcndec"> |
| XML_Size XMLCALL |
| XML_GetCurrentLineNumber(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return the line number of the position. The first line is reported as |
| <code>1</code>. |
| </div> |
| |
| <h4 id="XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</h4> |
| <pre class="fcndec"> |
| XML_Size XMLCALL |
| XML_GetCurrentColumnNumber(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return the offset, from the beginning of the current line, of |
| the position. |
| </div> |
| |
| <h4 id="XML_GetCurrentByteCount">XML_GetCurrentByteCount</h4> |
| <pre class="fcndec"> |
| int XMLCALL |
| XML_GetCurrentByteCount(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return the number of bytes in the current event. Returns |
| <code>0</code> if the event is inside a reference to an internal |
| entity and for the end-tag event for empty element tags (the later can |
| be used to distinguish empty-element tags from empty elements using |
| separate start and end tags). |
| </div> |
| |
| <h4 id="XML_GetInputContext">XML_GetInputContext</h4> |
| <pre class="fcndec"> |
| const char * XMLCALL |
| XML_GetInputContext(XML_Parser p, |
| int *offset, |
| int *size); |
| </pre> |
| <div class="fcndef"> |
| |
| <p>Returns the parser's input buffer, sets the integer pointed at by |
| <code>offset</code> to the offset within this buffer of the current |
| parse position, and set the integer pointed at by <code>size</code> to |
| the size of the returned buffer.</p> |
| |
| <p>This should only be called from within a handler during an active |
| parse and the returned buffer should only be referred to from within |
| the handler that made the call. This input buffer contains the |
| untranslated bytes of the input.</p> |
| |
| <p>Only a limited amount of context is kept, so if the event |
| triggering a call spans over a very large amount of input, the actual |
| parse position may be before the beginning of the buffer.</p> |
| |
| <p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always |
| return NULL.</p> |
| </div> |
| |
| <h3><a name="billion-laughs">Billion Laughs Attack Protection</a></h3> |
| |
| <p>The functions in this section configure the built-in |
| protection against various forms of |
| <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a>.</p> |
| |
| <h4 id="XML_SetBillionLaughsAttackProtectionMaximumAmplification">XML_SetBillionLaughsAttackProtectionMaximumAmplification</h4> |
| <pre class="fcndec"> |
| /* Added in Expat 2.4.0. */ |
| XML_Bool XMLCALL |
| XML_SetBillionLaughsAttackProtectionMaximumAmplification(XML_Parser p, |
| float maximumAmplificationFactor); |
| </pre> |
| <div class="fcndef"> |
| <p> |
| Sets the maximum tolerated amplification factor |
| for protection against |
| <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a> |
| (default: <code>100.0</code>) |
| of parser <code>p</code> to <code>maximumAmplificationFactor</code>, and |
| returns <code>XML_TRUE</code> upon success and <code>XML_FALSE</code> upon error. |
| </p> |
| |
| The amplification factor is calculated as .. |
| <pre> |
| amplification := (direct + indirect) / direct |
| </pre> |
| .. while parsing, whereas |
| <code>direct</code> is the number of bytes read from the primary document in parsing and |
| <code>indirect</code> is the number of bytes added by expanding entities and reading of external DTD files, combined. |
| |
| <p>For a call to <code>XML_SetBillionLaughsAttackProtectionMaximumAmplification</code> to succeed:</p> |
| <ul> |
| <li>parser <code>p</code> must be a non-<code>NULL</code> root parser (without any parent parsers) and</li> |
| <li><code>maximumAmplificationFactor</code> must be non-<code>NaN</code> and greater than or equal to <code>1.0</code>.</li> |
| </ul> |
| |
| <p> |
| <strong>Note:</strong> |
| If you ever need to increase this value for non-attack payload, |
| please <a href="https://github.com/libexpat/libexpat/issues">file a bug report</a>. |
| </p> |
| |
| <p> |
| <strong>Note:</strong> |
| Peak amplifications |
| of factor 15,000 for the entire payload and |
| of factor 30,000 in the middle of parsing |
| have been observed with small benign files in practice. |
| |
| So if you do reduce the maximum allowed amplification, |
| please make sure that the activation threshold is still big enough |
| to not end up with undesired false positives (i.e. benign files being rejected). |
| </p> |
| </div> |
| |
| <h4 id="XML_SetBillionLaughsAttackProtectionActivationThreshold">XML_SetBillionLaughsAttackProtectionActivationThreshold</h4> |
| <pre class="fcndec"> |
| /* Added in Expat 2.4.0. */ |
| XML_Bool XMLCALL |
| XML_SetBillionLaughsAttackProtectionActivationThreshold(XML_Parser p, |
| unsigned long long activationThresholdBytes); |
| </pre> |
| <div class="fcndef"> |
| <p> |
| Sets number of output bytes (including amplification from entity expansion and reading DTD files) |
| needed to activate protection against |
| <a href="https://en.wikipedia.org/wiki/Billion_laughs_attack">billion laughs attacks</a> |
| (default: <code>8 MiB</code>) |
| of parser <code>p</code> to <code>activationThresholdBytes</code>, and |
| returns <code>XML_TRUE</code> upon success and <code>XML_FALSE</code> upon error. |
| </p> |
| |
| <p>For a call to <code>XML_SetBillionLaughsAttackProtectionActivationThreshold</code> to succeed:</p> |
| <ul> |
| <li>parser <code>p</code> must be a non-<code>NULL</code> root parser (without any parent parsers).</li> |
| </ul> |
| |
| <p> |
| <strong>Note:</strong> |
| If you ever need to increase this value for non-attack payload, |
| please <a href="https://github.com/libexpat/libexpat/issues">file a bug report</a>. |
| </p> |
| |
| <p> |
| <strong>Note:</strong> |
| Activation thresholds below 4 MiB are known to break support for |
| <a href="https://en.wikipedia.org/wiki/Darwin_Information_Typing_Architecture">DITA</a> 1.3 payload |
| and are hence not recommended. |
| </p> |
| </div> |
| |
| <h3><a name="miscellaneous">Miscellaneous functions</a></h3> |
| |
| <p>The functions in this section either obtain state information from |
| the parser or can be used to dynamically set parser options.</p> |
| |
| <h4 id="XML_SetUserData">XML_SetUserData</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_SetUserData(XML_Parser p, |
| void *userData); |
| </pre> |
| <div class="fcndef"> |
| This sets the user data pointer that gets passed to handlers. It |
| overwrites any previous value for this pointer. Note that the |
| application is responsible for freeing the memory associated with |
| <code>userData</code> when it is finished with the parser. So if you |
| call this when there's already a pointer there, and you haven't freed |
| the memory associated with it, then you've probably just leaked |
| memory. |
| </div> |
| |
| <h4 id="XML_GetUserData">XML_GetUserData</h4> |
| <pre class="fcndec"> |
| void * XMLCALL |
| XML_GetUserData(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| This returns the user data pointer that gets passed to handlers. |
| It is actually implemented as a macro. |
| </div> |
| |
| <h4 id="XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_UseParserAsHandlerArg(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| After this is called, handlers receive the parser in their |
| <code>userData</code> arguments. The user data can still be obtained |
| using the <code><a href= "#XML_GetUserData" |
| >XML_GetUserData</a></code> function. |
| </div> |
| |
| <h4 id="XML_SetBase">XML_SetBase</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_SetBase(XML_Parser p, |
| const XML_Char *base); |
| </pre> |
| <div class="fcndef"> |
| Set the base to be used for resolving relative URIs in system |
| identifiers. The return value is <code>XML_STATUS_ERROR</code> if |
| there's no memory to store base, otherwise it's |
| <code>XML_STATUS_OK</code>. |
| </div> |
| |
| <h4 id="XML_GetBase">XML_GetBase</h4> |
| <pre class="fcndec"> |
| const XML_Char * XMLCALL |
| XML_GetBase(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Return the base for resolving relative URIs. |
| </div> |
| |
| <h4 id="XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</h4> |
| <pre class="fcndec"> |
| int XMLCALL |
| XML_GetSpecifiedAttributeCount(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| When attributes are reported to the start handler in the atts vector, |
| attributes that were explicitly set in the element occur before any |
| attributes that receive their value from default information in an |
| ATTLIST declaration. This function returns the number of attributes |
| that were explicitly set times two, thus giving the offset in the |
| <code>atts</code> array passed to the start tag handler of the first |
| attribute set due to defaults. It supplies information for the last |
| call to a start handler. If called inside a start handler, then that |
| means the current call. |
| </div> |
| |
| <h4 id="XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</h4> |
| <pre class="fcndec"> |
| int XMLCALL |
| XML_GetIdAttributeIndex(XML_Parser p); |
| </pre> |
| <div class="fcndef"> |
| Returns the index of the ID attribute passed in the atts array in the |
| last call to <code><a href= "#XML_StartElementHandler" |
| >XML_StartElementHandler</a></code>, or -1 if there is no ID |
| attribute. If called inside a start handler, then that means the |
| current call. |
| </div> |
| |
| <h4 id="XML_GetAttributeInfo">XML_GetAttributeInfo</h4> |
| <pre class="fcndec"> |
| const XML_AttrInfo * XMLCALL |
| XML_GetAttributeInfo(XML_Parser parser); |
| </pre> |
| <pre class="signature"> |
| typedef struct { |
| XML_Index nameStart; /* Offset to beginning of the attribute name. */ |
| XML_Index nameEnd; /* Offset after the attribute name's last byte. */ |
| XML_Index valueStart; /* Offset to beginning of the attribute value. */ |
| XML_Index valueEnd; /* Offset after the attribute value's last byte. */ |
| } XML_AttrInfo; |
| </pre> |
| <div class="fcndef"> |
| Returns an array of <code>XML_AttrInfo</code> structures for the |
| attribute/value pairs passed in the last call to the |
| <code>XML_StartElementHandler</code> that were specified |
| in the start-tag rather than defaulted. Each attribute/value pair counts |
| as 1; thus the number of entries in the array is |
| <code>XML_GetSpecifiedAttributeCount(parser) / 2</code>. |
| </div> |
| |
| <h4 id="XML_SetEncoding">XML_SetEncoding</h4> |
| <pre class="fcndec"> |
| enum XML_Status XMLCALL |
| XML_SetEncoding(XML_Parser p, |
| const XML_Char *encoding); |
| </pre> |
| <div class="fcndef"> |
| Set the encoding to be used by the parser. It is equivalent to |
| passing a non-null encoding argument to the parser creation functions. |
| It must not be called after <code><a href= "#XML_Parse" |
| >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" |
| >XML_ParseBuffer</a></code> have been called on the given parser. |
| Returns <code>XML_STATUS_OK</code> on success or |
| <code>XML_STATUS_ERROR</code> on error. |
| </div> |
| |
| <h4 id="XML_SetParamEntityParsing">XML_SetParamEntityParsing</h4> |
| <pre class="fcndec"> |
| int XMLCALL |
| XML_SetParamEntityParsing(XML_Parser p, |
| enum XML_ParamEntityParsing code); |
| </pre> |
| <div class="fcndef"> |
| This enables parsing of parameter entities, including the external |
| parameter entity that is the external DTD subset, according to |
| <code>code</code>. |
| The choices for <code>code</code> are: |
| <ul> |
| <li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> |
| <li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> |
| <li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> |
| </ul> |
| <b>Note:</b> If <code>XML_SetParamEntityParsing</code> is called after |
| <code>XML_Parse</code> or <code>XML_ParseBuffer</code>, then it has |
| no effect and will always return 0. |
| </div> |
| |
| <h4 id="XML_SetHashSalt">XML_SetHashSalt</h4> |
| <pre class="fcndec"> |
| int XMLCALL |
| XML_SetHashSalt(XML_Parser p, |
| unsigned long hash_salt); |
| </pre> |
| <div class="fcndef"> |
| Sets the hash salt to use for internal hash calculations. |
| Helps in preventing DoS attacks based on predicting hash |
| function behavior. In order to have an effect this must be called |
| before parsing has started. Returns 1 if successful, 0 when called |
| after <code>XML_Parse</code> or <code>XML_ParseBuffer</code>. |
| <p><b>Note:</b> This call is optional, as the parser will auto-generate |
| a new random salt value if no value has been set at the start of parsing.</p> |
| <p><b>Note:</b> One should not call <code>XML_SetHashSalt</code> with a |
| hash salt value of 0, as this value is used as sentinel value to indicate |
| that <code>XML_SetHashSalt</code> has <b>not</b> been called. Consequently |
| such a call will have no effect, even if it returns 1.</p> |
| </div> |
| |
| <h4 id="XML_UseForeignDTD">XML_UseForeignDTD</h4> |
| <pre class="fcndec"> |
| enum XML_Error XMLCALL |
| XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); |
| </pre> |
| <div class="fcndef"> |
| <p>This function allows an application to provide an external subset |
| for the document type declaration for documents which do not specify |
| an external subset of their own. For documents which specify an |
| external subset in their DOCTYPE declaration, the application-provided |
| subset will be ignored. If the document does not contain a DOCTYPE |
| declaration at all and <code>useDTD</code> is true, the |
| application-provided subset will be parsed, but the |
| <code>startDoctypeDeclHandler</code> and |
| <code>endDoctypeDeclHandler</code> functions, if set, will not be |
| called. The setting of parameter entity parsing, controlled using |
| <code><a href= "#XML_SetParamEntityParsing" |
| >XML_SetParamEntityParsing</a></code>, will be honored.</p> |
| |
| <p>The application-provided external subset is read by calling the |
| external entity reference handler set via <code><a href= |
| "#XML_SetExternalEntityRefHandler" |
| >XML_SetExternalEntityRefHandler</a></code> with both |
| <code>publicId</code> and <code>systemId</code> set to NULL.</p> |
| |
| <p>If this function is called after parsing has begun, it returns |
| <code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores |
| <code>useDTD</code>. If called when Expat has been compiled without |
| DTD support, it returns |
| <code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it |
| returns <code>XML_ERROR_NONE</code>.</p> |
| |
| <p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing |
| <code>useDTD == XML_TRUE</code> will make the parser behave as if |
| the document had a DTD with an external subset. This holds true even if |
| the external entity reference handler returns without action.</p> |
| </div> |
| |
| <h4 id="XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_SetReturnNSTriplet(XML_Parser parser, |
| int do_nst); |
| </pre> |
| <div class="fcndef"> |
| <p> |
| This function only has an effect when using a parser created with |
| <code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, |
| i.e. when namespace processing is in effect. The <code>do_nst</code> |
| sets whether or not prefixes are returned with names qualified with a |
| namespace prefix. If this function is called with <code>do_nst</code> |
| non-zero, then afterwards namespace qualified names (that is qualified |
| with a prefix as opposed to belonging to a default namespace) are |
| returned as a triplet with the three parts separated by the namespace |
| separator specified when the parser was created. The order of |
| returned parts is URI, local name, and prefix.</p> <p>If |
| <code>do_nst</code> is zero, then namespaces are reported in the |
| default manner, URI then local_name separated by the namespace |
| separator.</p> |
| </div> |
| |
| <h4 id="XML_DefaultCurrent">XML_DefaultCurrent</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_DefaultCurrent(XML_Parser parser); |
| </pre> |
| <div class="fcndef"> |
| This can be called within a handler for a start element, end element, |
| processing instruction or character data. It causes the corresponding |
| markup to be passed to the default handler set by <code><a |
| href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or |
| <code><a href="#XML_SetDefaultHandlerExpand" |
| >XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is |
| not a default handler. |
| </div> |
| |
| <h4 id="XML_ExpatVersion">XML_ExpatVersion</h4> |
| <pre class="fcndec"> |
| XML_LChar * XMLCALL |
| XML_ExpatVersion(); |
| </pre> |
| <div class="fcndef"> |
| Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). |
| </div> |
| |
| <h4 id="XML_ExpatVersionInfo">XML_ExpatVersionInfo</h4> |
| <pre class="fcndec"> |
| struct XML_Expat_Version XMLCALL |
| XML_ExpatVersionInfo(); |
| </pre> |
| <pre class="signature"> |
| typedef struct { |
| int major; |
| int minor; |
| int micro; |
| } XML_Expat_Version; |
| </pre> |
| <div class="fcndef"> |
| Return the library version information as a structure. |
| Some macros are also defined that support compile-time tests of the |
| library version: |
| <ul> |
| <li><code>XML_MAJOR_VERSION</code></li> |
| <li><code>XML_MINOR_VERSION</code></li> |
| <li><code>XML_MICRO_VERSION</code></li> |
| </ul> |
| Testing these constants is currently the best way to determine if |
| particular parts of the Expat API are available. |
| </div> |
| |
| <h4 id="XML_GetFeatureList">XML_GetFeatureList</h4> |
| <pre class="fcndec"> |
| const XML_Feature * XMLCALL |
| XML_GetFeatureList(); |
| </pre> |
| <pre class="signature"> |
| enum XML_FeatureEnum { |
| XML_FEATURE_END = 0, |
| XML_FEATURE_UNICODE, |
| XML_FEATURE_UNICODE_WCHAR_T, |
| XML_FEATURE_DTD, |
| XML_FEATURE_CONTEXT_BYTES, |
| XML_FEATURE_MIN_SIZE, |
| XML_FEATURE_SIZEOF_XML_CHAR, |
| XML_FEATURE_SIZEOF_XML_LCHAR, |
| XML_FEATURE_NS, |
| XML_FEATURE_LARGE_SIZE |
| }; |
| |
| typedef struct { |
| enum XML_FeatureEnum feature; |
| XML_LChar *name; |
| long int value; |
| } XML_Feature; |
| </pre> |
| <div class="fcndef"> |
| <p>Returns a list of "feature" records, providing details on how |
| Expat was configured at compile time. Most applications should not |
| need to worry about this, but this information is otherwise not |
| available from Expat. This function allows code that does need to |
| check these features to do so at runtime.</p> |
| |
| <p>The return value is an array of <code>XML_Feature</code>, |
| terminated by a record with a <code>feature</code> of |
| <code>XML_FEATURE_END</code> and <code>name</code> of NULL, |
| identifying the feature-test macros Expat was compiled with. Since an |
| application that requires this kind of information needs to determine |
| the type of character the <code>name</code> points to, records for the |
| <code>XML_FEATURE_SIZEOF_XML_CHAR</code> and |
| <code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the |
| beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> |
| and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at |
| all.</p> |
| |
| <p>Some features have an associated value. If there isn't an |
| associated value, the <code>value</code> field is set to 0. At this |
| time, the following features have been defined to have values:</p> |
| |
| <dl> |
| <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> |
| <dd>The number of bytes occupied by one <code>XML_Char</code> |
| character.</dd> |
| <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> |
| <dd>The number of bytes occupied by one <code>XML_LChar</code> |
| character.</dd> |
| <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> |
| <dd>The maximum number of characters of context which can be |
| reported by <code><a href= "#XML_GetInputContext" |
| >XML_GetInputContext</a></code>.</dd> |
| </dl> |
| </div> |
| |
| <h4 id="XML_FreeContentModel">XML_FreeContentModel</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_FreeContentModel(XML_Parser parser, XML_Content *model); |
| </pre> |
| <div class="fcndef"> |
| Function to deallocate the <code>model</code> argument passed to the |
| <code>XML_ElementDeclHandler</code> callback set using <code><a |
| href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. |
| This function should not be used for any other purpose. |
| </div> |
| |
| <p>The following functions allow external code to share the memory |
| allocator an <code>XML_Parser</code> has been configured to use. This |
| is especially useful for third-party libraries that interact with a |
| parser object created by application code, or heavily layered |
| applications. This can be essential when using dynamically loaded |
| libraries which use different C standard libraries (this can happen on |
| Windows, at least).</p> |
| |
| <h4 id="XML_MemMalloc">XML_MemMalloc</h4> |
| <pre class="fcndec"> |
| void * XMLCALL |
| XML_MemMalloc(XML_Parser parser, size_t size); |
| </pre> |
| <div class="fcndef"> |
| Allocate <code>size</code> bytes of memory using the allocator the |
| <code>parser</code> object has been configured to use. Returns a |
| pointer to the memory or NULL on failure. Memory allocated in this |
| way must be freed using <code><a href="#XML_MemFree" |
| >XML_MemFree</a></code>. |
| </div> |
| |
| <h4 id="XML_MemRealloc">XML_MemRealloc</h4> |
| <pre class="fcndec"> |
| void * XMLCALL |
| XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); |
| </pre> |
| <div class="fcndef"> |
| Allocate <code>size</code> bytes of memory using the allocator the |
| <code>parser</code> object has been configured to use. |
| <code>ptr</code> must point to a block of memory allocated by <code><a |
| href="#XML_MemMalloc" >XML_MemMalloc</a></code> or |
| <code>XML_MemRealloc</code>, or be NULL. This function tries to |
| expand the block pointed to by <code>ptr</code> if possible. Returns |
| a pointer to the memory or NULL on failure. On success, the original |
| block has either been expanded or freed. On failure, the original |
| block has not been freed; the caller is responsible for freeing the |
| original block. Memory allocated in this way must be freed using |
| <code><a href="#XML_MemFree" |
| >XML_MemFree</a></code>. |
| </div> |
| |
| <h4 id="XML_MemFree">XML_MemFree</h4> |
| <pre class="fcndec"> |
| void XMLCALL |
| XML_MemFree(XML_Parser parser, void *ptr); |
| </pre> |
| <div class="fcndef"> |
| Free a block of memory pointed to by <code>ptr</code>. The block must |
| have been allocated by <code><a href="#XML_MemMalloc" |
| >XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. |
| </div> |
| |
| <hr /> |
| |
| <div class="footer"> |
| Found a bug in the documentation? |
| <a href="https://github.com/libexpat/libexpat/issues">Please file a bug report.</a> |
| </div> |
| |
| </div> |
| </body> |
| </html> |