src/xml_aux.c

   1 /*
   2 Copyright (c) 2008 Instituto Nokia de Tecnologia
   3 All rights reserved.
   4
   5 Redistribution and use in source and binary forms, with or without modification,
   6 are permitted provided that the following conditions are met:
   7
   8     * Redistributions of source code must retain the above copyright notice,
   9     this list of conditions and the following disclaimer.
  10     * Redistributions in binary form must reproduce the above copyright notice,
  11     this list of conditions and the following disclaimer in the documentation
  12     and/or other materials provided with the distribution.
  13     * Neither the name of the INdT nor the names of its contributors
  14     may be used to endorse or promote products derived from this software
  15     without specific prior written permission.
  16
  17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  18 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  21 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  22 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  23 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  24 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  25 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  26 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  27 POSSIBILITY OF SUCH DAMAGE.
  28 */
  29
  30 /**
  31  * @file   xml_aux.h
  32  * @author Adenilson Cavalcanti da Silva <adenilson.silva@indt.org.br>
  33  * @date   Fri Mar 28 14:31:21 2008
  34  *
  35  * @brief  Auxiliary code to parse XML using XPath, iIt depends on libxml.
  36  *
  37  * I started with 'xpath1.c' libxml example written by Aleksey Sanin
  38  * (which uses MIT license).
  39  * In the end my code turn out to be rather different from him, but
  40  * I decided to keep the same function names.
  41  *
  42  */
  43
  44 #include "xml_aux.h"
  45
  46 int register_namespaces(xmlXPathContext *xpathCtx, const xmlChar *name_space,
  47                         const xmlChar* href)
  48 {
  49         int result = -1;
  50         if (!xpathCtx)
  51                 goto exit;
  52         if (name_space && href) {
  53                 /* do register namespace */
  54                 if(xmlXPathRegisterNs(xpathCtx, name_space, href) != 0) {
  55                         fprintf(stderr,"Error: unable to register NS with"
  56                                 "prefix=\"%s\" and href=\"%s\"\n",
  57                                 name_space, href);
  58                         goto exit;
  59                 }
  60         }
  61         else {
  62                 if (register_namespaces(xpathCtx, atom_ns, atom_href) ||
  63                     register_namespaces(xpathCtx, gd_ns, gd_href) ||
  64                     register_namespaces(xpathCtx, gContact_ns, gContact_href) ||
  65                     register_namespaces(xpathCtx, open_search_ns,
  66                                         open_search_href) ||
  67                     register_namespaces(xpathCtx, gContact_ns, gContact_href))
  68                         goto exit;
  69         }
  70
  71         result = 0;
  72 exit:
  73         return result;
  74
  75 }
  76
  77 xmlXPathObject* execute_xpath_expression(xmlDoc *doc,
  78                                          const xmlChar* xpathExpr,
  79                                          xmlXPathContext *xpathCtx)
  80 {
  81         unsigned char ownership = 0;
  82         xmlXPathObject *xpath_obj = NULL;
  83         if (!xpathCtx) {
  84                 ownership = 1;
  85                 xpathCtx = xmlXPathNewContext(doc);
  86                 if (xpathCtx == NULL) {
  87                         fprintf(stderr,"Error: unable to create new XPath"
  88                                 "context\n");
  89                         goto exit;
  90                 }
  91
  92                 if (register_namespaces(xpathCtx, NULL, NULL))
  93                                 goto exit;
  94
  95         }
  96
  97         xpath_obj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
  98         if (ownership && (xpathCtx != NULL))
  99                 xmlXPathFreeContext(xpathCtx);
 100
 101 exit:
 102         return xpath_obj;
 103
 104 }
 105
 106 int xmlentry_init_resources(xmlTextWriter **writer, xmlBuffer **buffer)
 107 {
 108         int result = -1;
 109         *buffer = xmlBufferCreate();
 110         if (!buffer)
 111                 goto exit;
 112
 113         *writer = xmlNewTextWriterMemory(*buffer, 0);
 114         if (!*writer)
 115                 goto exit;
 116
 117         result = 0;
 118
 119 exit:
 120         return result;
 121
 122 }
 123
 124
 125 void xmlentry_destroy_resources(xmlTextWriter **writer, xmlBuffer **buffer)
 126 {
 127         if (!writer && !buffer)
 128                 return;
 129
 130         if (writer)
 131                 if (*writer) {
 132                         xmlFreeTextWriter(*writer);
 133                         *writer = NULL;
 134                 }
 135
 136         if (buffer)
 137                 if (*buffer) {
 138                         xmlBufferFree(*buffer);
 139                         *buffer = NULL;
 140                 }
 141 }