tests/regression/tools/mi/extract_xml.c

   1 /*
   2  * Copyright (C) 2014 - Jonathan Rajotte <jonathan.r.julien@gmail.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  */
  16
  17 /*
  18  * Usage: extract_xml [-v|-e] xml_path xpath_expression
  19  * Evaluate XPath expression and prints result node set.
  20  * args[1] path to the xml file
  21  * args[2] xpath expression to extract
  22  * If -e look if node exist return "true" else nothing
  23  * If -v is set the name of the node will appear with his value delimited by
  24  * a semicolon(;)
  25  * Ex:
  26  * Command:extract_xml ../file.xml /test/node/text()
  27  * Output:
  28  *     a
  29  *     b
  30  *     c
  31  * With -v
  32  *     node;a;
  33  *     node;b;
  34  *     node;c;
  35  */
  36 #include <stdlib.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <assert.h>
  40 #include <unistd.h>
  41
  42 #include <libxml/tree.h>
  43 #include <libxml/parser.h>
  44 #include <libxml/xpath.h>
  45 #include <libxml/xpathInternals.h>
  46 #include <common/defaults.h>
  47
  48 #if defined(LIBXML_XPATH_ENABLED)
  49
  50
  51 int opt_verbose;
  52 int node_exist;
  53
  54 /**
  55  * print_xpath_nodes:
  56  * nodes:  the nodes set.
  57  * output: the output file handle.
  58  *
  59  * Print the node content to the file
  60  */
  61 static int print_xpath_nodes(xmlDocPtr doc, xmlNodeSetPtr nodes, FILE *output)
  62 {
  63         int ret = 0;
  64         int size;
  65         int i;
  66
  67         xmlNodePtr cur;
  68         xmlChar *node_child_value_string = NULL;
  69
  70         assert(output);
  71         size = (nodes) ? nodes->nodeNr : 0;
  72
  73         for (i = 0; i < size; ++i) {
  74                 assert(nodes->nodeTab[i]);
  75
  76                 if (nodes->nodeTab[i]->type == XML_NAMESPACE_DECL) {
  77                         fprintf(stderr, "ERR:%s\n",
  78                                         "This executable does not support xml namespacing\n");
  79                         ret = -1;
  80                         goto end;
  81                 } else if (nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
  82                         cur = nodes->nodeTab[i];
  83
  84                         if (xmlChildElementCount(cur) == 0) {
  85                                 if (xmlNodeIsText(cur->children)) {
  86                                         node_child_value_string = xmlNodeListGetString(doc,
  87                                                         cur->children, 1);
  88                                         if (node_exist) {
  89                                                 fprintf(output, "true\n");
  90                                         } else if (opt_verbose) {
  91                                                 fprintf(output, "%s;%s;\n", cur->name,
  92                                                                 node_child_value_string);
  93                                         } else {
  94                                                 fprintf(output, "%s\n",
  95                                                                 node_child_value_string);
  96                                         }
  97                                         xmlFree(node_child_value_string);
  98                                 } else {
  99                                         /* We don't want to print non-final element */
 100                                         if (node_exist) {
 101                                                 fprintf(output, "true\n");
 102                                         } else {
 103                                                 fprintf(stderr, "ERR:%s\n",
 104                                                                 "Xpath expression return non-final xml element");
 105                                                 ret = -1;
 106                                                 goto end;
 107                                         }
 108                                 }
 109                         } else {
 110                                 if (node_exist) {
 111                                         fprintf(output, "true\n");
 112                                 } else {
 113                                         /* We don't want to print non-final element */
 114                                         fprintf(stderr, "ERR:%s\n",
 115                                                         "Xpath expression return non-final xml element");
 116                                         ret = -1;
 117                                         goto end;
 118                                 }
 119                         }
 120
 121                 } else {
 122                         cur = nodes->nodeTab[i];
 123                         if (node_exist) {
 124                                 fprintf(output, "true\n");
 125                         } else if (opt_verbose) {
 126                                 fprintf(output, "%s;%s;\n", cur->parent->name, cur->content);
 127                         } else {
 128                                 fprintf(output, "%s\n", cur->content);
 129                         }
 130                 }
 131         }
 132         /* Command Success */
 133         ret = 0;
 134
 135 end:
 136         return ret;
 137 }
 138
 139 static int register_lttng_namespace(xmlXPathContextPtr xpathCtx)
 140 {
 141         int ret;
 142         xmlChar *prefix;
 143         xmlChar *ns = NULL;
 144
 145         prefix = xmlCharStrdup("lttng");
 146         if (!prefix) {
 147                 ret = -1;
 148                 goto end;
 149         }
 150
 151         ns = xmlCharStrdup(DEFAULT_LTTNG_MI_NAMESPACE);
 152         if (!ns) {
 153                 ret = -1;
 154                 goto end;
 155         }
 156
 157         ret = xmlXPathRegisterNs(xpathCtx, prefix, ns);
 158         xmlFree(prefix);
 159 end:
 160         xmlFree(ns);
 161         return ret;
 162 }
 163
 164 /*
 165  * Extract element corresponding to xpath
 166  * xml_path     The path to the xml file
 167  * xpath:       The xpath to evaluate.
 168  *
 169  * Evaluate an xpath expression onto an xml file.
 170  * and print the result one by line.
 171  *
 172  * Returns 0 on success and a negative value otherwise.
 173  */
 174 static int extract_xpath(const char *xml_path, const xmlChar *xpath)
 175 {
 176         int ret;
 177         xmlDocPtr doc = NULL;
 178         xmlXPathContextPtr xpathCtx = NULL;
 179         xmlXPathObjectPtr xpathObj = NULL;
 180
 181         assert(xml_path);
 182         assert(xpath);
 183
 184         /* Parse the xml file */
 185         doc = xmlParseFile(xml_path);
 186         if (!doc) {
 187                 fprintf(stderr, "ERR parsing: xml file invalid \"%s\"\n", xml_path);
 188                 return -1;
 189         }
 190
 191         /* Initialize a xpath context */
 192         xpathCtx = xmlXPathNewContext(doc);
 193         if (!xpathCtx) {
 194                 fprintf(stderr, "ERR: XPath context invalid\n");
 195                 xmlFreeDoc(doc);
 196                 return -1;
 197         }
 198
 199         /* Register the LTTng MI namespace */
 200         ret = register_lttng_namespace(xpathCtx);
 201         if (ret) {
 202                 fprintf(stderr, "ERR: Could not register lttng namespace\n");
 203                 xmlXPathFreeContext(xpathCtx);
 204                 xmlFreeDoc(doc);
 205                 return -1;
 206         }
 207
 208         /* Evaluate xpath expression */
 209         xpathObj = xmlXPathEvalExpression(xpath, xpathCtx);
 210         if (!xpathObj) {
 211                 fprintf(stderr, "ERR: invalid xpath expression \"%s\"\n", xpath);
 212                 xmlXPathFreeContext(xpathCtx);
 213                 xmlFreeDoc(doc);
 214                 return -1;
 215         }
 216
 217         /* Print results */
 218         if (print_xpath_nodes(doc, xpathObj->nodesetval, stdout)) {
 219                 xmlXPathFreeObject(xpathObj);
 220                 xmlXPathFreeContext(xpathCtx);
 221                 xmlFreeDoc(doc);
 222                 return -1;
 223         }
 224
 225         /* Cleanup */
 226         xmlXPathFreeObject(xpathObj);
 227         xmlXPathFreeContext(xpathCtx);
 228         xmlFreeDoc(doc);
 229
 230         return 0;
 231 }
 232
 233 int main(int argc, char **argv)
 234 {
 235         int opt;
 236
 237         /* Parse command line and process file */
 238         while ((opt = getopt(argc, argv, "ve")) != -1) {
 239                 switch (opt) {
 240                 case 'v':
 241                         opt_verbose = 1;
 242                         break;
 243                 case 'e':
 244                         node_exist = 1;
 245                         break;
 246                 default:
 247                         abort();
 248                 }
 249         }
 250
 251         if (!(optind + 1 < argc)) {
 252                 fprintf(stderr, "ERR:%s\n", "Arguments missing");
 253                 return -1;
 254         }
 255
 256         /* Init libxml */
 257         xmlInitParser();
 258         xmlKeepBlanksDefault(0);
 259         if (access(argv[optind], F_OK)) {
 260                 fprintf(stderr, "ERR:%s\n", "Xml path not valid");
 261                 return -1;
 262         }
 263         /* Do the main job */
 264         if (extract_xpath(argv[optind], (xmlChar *)argv[optind+1])) {
 265                 return -1;
 266         }
 267
 268         /* Shutdown libxml */
 269         xmlCleanupParser();
 270
 271         return 0;
 272 }
 273
 274 #else
 275 int main(void)
 276 {
 277         fprintf(stderr, "XPath support not compiled in\n");
 278         return -1;
 279 }
 280 #endif