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/** **************************************************************************
* simplexml.c
*
* Copyright 2008 Bryan Ischo <bryan@ischo.com>
*
* This file is part of libs3.
*
* libs3 is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, version 3 of the License.
*
* libs3 is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License version 3
* along with libs3, in a file named COPYING. If not, see
* <http://www.gnu.org/licenses/>.
*
************************************************************************** **/
#include <libxml/parser.h>
#include <string.h>
#include "simplexml.h"
// Use libxml2 for parsing XML. XML is severely overused in modern
// computing. It is useful for only a very small subset of tasks, but
// software developers who don't know better and are afraid to go against the
// grain use it for everything, and in most cases, it is completely
// inappropriate. Usually, the document structure is severely under-specified
// as well, as is the case with S3. We do our best by just caring about the
// most important aspects of the S3 "XML document" responses: the elements and
// their values. The SAX API (just about the lamest API ever devised and
// proof that XML sucks - well, the real proof is how crappy all of the XML
// parsing libraries are, including libxml2 - but I digress) is used here
// because we don't need much from the parser and SAX is fast and low memory.
//
// Note that for simplicity we assume all ASCII here. No attempts are made to
// detect non-ASCII sequences in utf-8 and convert them into ASCII in any way.
// S3 appears to only use ASCII anyway.
static xmlEntityPtr saxGetEntity(void *user_data, const xmlChar *name)
{
return xmlGetPredefinedEntity(name);
}
static void saxStartElement(void *user_data, const xmlChar *nameUtf8,
const xmlChar **attr)
{
SimpleXml *simpleXml = (SimpleXml *) user_data;
if (simpleXml->status != S3StatusOK) {
return;
}
// Assume that name has no non-ASCII in it
char *name = (char *) nameUtf8;
// Append the element to the element path
int len = strlen(name);
if ((simpleXml->elementPathLen + len + 1) >=
sizeof(simpleXml->elementPath)) {
// Cannot handle this element, stop!
simpleXml->status = S3StatusXmlParseFailure;
return;
}
if (simpleXml->elementPathLen) {
simpleXml->elementPath[simpleXml->elementPathLen++] = '/';
}
strcpy(&(simpleXml->elementPath[simpleXml->elementPathLen]), name);
simpleXml->elementPathLen += len;
}
static void saxEndElement(void *user_data, const xmlChar *name)
{
SimpleXml *simpleXml = (SimpleXml *) user_data;
if (simpleXml->status != S3StatusOK) {
return;
}
// Call back with 0 data
simpleXml->status = (*(simpleXml->callback))
(simpleXml->elementPath, 0, 0, simpleXml->callbackData);
while ((simpleXml->elementPathLen > 0) &&
(simpleXml->elementPath[simpleXml->elementPathLen] != '/')) {
simpleXml->elementPathLen--;
}
simpleXml->elementPath[simpleXml->elementPathLen] = 0;
}
static void saxCharacters(void *user_data, const xmlChar *ch, int len)
{
SimpleXml *simpleXml = (SimpleXml *) user_data;
if (simpleXml->status != S3StatusOK) {
return;
}
simpleXml->status = (*(simpleXml->callback))
(simpleXml->elementPath, (char *) ch, len, simpleXml->callbackData);
}
static void saxError(void *user_data, const char *msg, ...)
{
SimpleXml *simpleXml = (SimpleXml *) user_data;
if (simpleXml->status != S3StatusOK) {
return;
}
simpleXml->status = S3StatusXmlParseFailure;
}
static struct _xmlSAXHandler saxHandlerG =
{
0, // internalSubsetSAXFunc
0, // isStandaloneSAXFunc
0, // hasInternalSubsetSAXFunc
0, // hasExternalSubsetSAXFunc
0, // resolveEntitySAXFunc
&saxGetEntity, // getEntitySAXFunc
0, // entityDeclSAXFunc
0, // notationDeclSAXFunc
0, // attributeDeclSAXFunc
0, // elementDeclSAXFunc
0, // unparsedEntityDeclSAXFunc
0, // setDocumentLocatorSAXFunc
0, // startDocumentSAXFunc
0, // endDocumentSAXFunc
&saxStartElement, // startElementSAXFunc
&saxEndElement, // endElementSAXFunc
0, // referenceSAXFunc
&saxCharacters, // charactersSAXFunc
0, // ignorableWhitespaceSAXFunc
0, // processingInstructionSAXFunc
0, // commentSAXFunc
0, // warningSAXFunc
&saxError, // errorSAXFunc
&saxError, // fatalErrorSAXFunc
0, // getParameterEntitySAXFunc
&saxCharacters, // cdataBlockSAXFunc
0, // externalSubsetSAXFunc
0, // initialized
0, // _private
0, // startElementNsSAX2Func
0, // endElementNsSAX2Func
0 // xmlStructuredErrorFunc serror;
};
void simplexml_initialize(SimpleXml *simpleXml,
SimpleXmlCallback *callback, void *callbackData)
{
simpleXml->callback = callback;
simpleXml->callbackData = callbackData;
simpleXml->elementPathLen = 0;
simpleXml->status = S3StatusOK;
simpleXml->xmlParser = 0;
}
void simplexml_deinitialize(SimpleXml *simpleXml)
{
if (simpleXml->xmlParser) {
xmlFreeParserCtxt(simpleXml->xmlParser);
}
}
S3Status simplexml_add(SimpleXml *simpleXml, const char *data, int dataLen)
{
if (!simpleXml->xmlParser &&
(!(simpleXml->xmlParser = xmlCreatePushParserCtxt
(&saxHandlerG, simpleXml, 0, 0, 0)))) {
return S3StatusInternalError;
}
if (xmlParseChunk((xmlParserCtxtPtr) simpleXml->xmlParser,
data, dataLen, 0)) {
return S3StatusXmlParseFailure;
}
return simpleXml->status;
}
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