tests/utils/xml-utils/extract_xml.c

   1 /*
   2  * Copyright (C) 2014 Jonathan Rajotte <jonathan.r.julien@gmail.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 /*
   9  * Usage: extract_xml [-v|-e] xml_path xpath_expression
  10  * Evaluate XPath expression and prints result node set.
  11  * args[1] path to the xml file
  12  * args[2] xpath expression to extract
  13  * If -e look if node exist return "true" else nothing
  14  * If -v is set the name of the node will appear with his value delimited by
  15  * a semicolon(;)
  16  * Ex:
  17  * Command:extract_xml ../file.xml /test/node/text()
  18  * Output:
  19  *     a
  20  *     b
  21  *     c
  22  * With -v
  23  *     node;a;
  24  *     node;b;
  25  *     node;c;
  26  */
  27 #include <stdbool.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32
  33 #include <libxml/tree.h>
  34 #include <libxml/parser.h>
  35 #include <libxml/xpath.h>
  36 #include <libxml/xpathInternals.h>
  37 #include <common/defaults.h>
  38
  39 #if defined(LIBXML_XPATH_ENABLED)
  40
  41 static int opt_verbose;
  42 static int node_exist;
  43 static bool result = false;
  44
  45 /**
  46  * print_xpath_nodes:
  47  * nodes:  the nodes set.
  48  * output: the output file handle.
  49  *
  50  * Print the node content to the file
  51  */
  52 static int print_xpath_nodes(xmlDocPtr doc, xmlNodeSetPtr nodes, FILE *output)
  53 {
  54         int ret = 0;
  55         int size;
  56         int i;
  57
  58         xmlNodePtr cur;
  59         xmlChar *node_child_value_string = NULL;
  60
  61         LTTNG_ASSERT(output);
  62         size = (nodes) ? nodes->nodeNr : 0;
  63
  64         for (i = 0; i < size; ++i) {
  65                 LTTNG_ASSERT(nodes->nodeTab[i]);
  66
  67                 if (nodes->nodeTab[i]->type == XML_NAMESPACE_DECL) {
  68                         fprintf(stderr, "ERR:%s\n",
  69                                         "This executable does not support xml namespacing\n");
  70                         ret = -1;
  71                         goto end;
  72                 } else if (nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
  73                         cur = nodes->nodeTab[i];
  74
  75                         if (xmlChildElementCount(cur) == 0) {
  76                                 if (xmlNodeIsText(cur->children)) {
  77                                         node_child_value_string = xmlNodeListGetString(doc,
  78                                                         cur->children, 1);
  79                                         if (node_exist) {
  80                                                 result = true;
  81                                         } else if (opt_verbose) {
  82                                                 fprintf(output, "%s;%s;\n", cur->name,
  83                                                                 node_child_value_string);
  84                                         } else {
  85                                                 fprintf(output, "%s\n",
  86                                                                 node_child_value_string);
  87                                         }
  88                                         xmlFree(node_child_value_string);
  89                                 } else {
  90                                         /* We don't want to print non-final element */
  91                                         if (node_exist) {
  92                                                 result = true;
  93                                         } else {
  94                                                 fprintf(stderr, "ERR:%s\n",
  95                                                                 "Xpath expression return non-final xml element");
  96                                                 ret = -1;
  97                                                 goto end;
  98                                         }
  99                                 }
 100                         } else {
 101                                 if (node_exist) {
 102                                         result = true;
 103                                 } else {
 104                                         /* We don't want to print non-final element */
 105                                         fprintf(stderr, "ERR:%s\n",
 106                                                         "Xpath expression return non-final xml element");
 107                                         ret = -1;
 108                                         goto end;
 109                                 }
 110                         }
 111
 112                 } else {
 113                         cur = nodes->nodeTab[i];
 114                         if (node_exist) {
 115                                 result = true;
 116                         } else if (opt_verbose) {
 117                                 fprintf(output, "%s;%s;\n", cur->parent->name, cur->content);
 118                         } else {
 119                                 fprintf(output, "%s\n", cur->content);
 120                         }
 121                 }
 122         }
 123         /* Command Success */
 124         ret = 0;
 125
 126 end:
 127         return ret;
 128 }
 129
 130 static int register_lttng_namespace(xmlXPathContextPtr xpathCtx)
 131 {
 132         int ret;
 133         xmlChar *prefix;
 134         xmlChar *ns = NULL;
 135
 136         prefix = xmlCharStrdup("lttng");
 137         if (!prefix) {
 138                 ret = -1;
 139                 goto end;
 140         }
 141
 142         ns = xmlCharStrdup(DEFAULT_LTTNG_MI_NAMESPACE);
 143         if (!ns) {
 144                 ret = -1;
 145                 goto end;
 146         }
 147
 148         ret = xmlXPathRegisterNs(xpathCtx, prefix, ns);
 149 end:
 150         xmlFree(prefix);
 151         xmlFree(ns);
 152         return ret;
 153 }
 154
 155 /*
 156  * Extract element corresponding to xpath
 157  * xml_path     The path to the xml file
 158  * xpath:       The xpath to evaluate.
 159  *
 160  * Evaluate an xpath expression onto an xml file.
 161  * and print the result one by line.
 162  *
 163  * Returns 0 on success and a negative value otherwise.
 164  */
 165 static int extract_xpath(const char *xml_path, const xmlChar *xpath)
 166 {
 167         int ret;
 168         xmlDocPtr doc = NULL;
 169         xmlXPathContextPtr xpathCtx = NULL;
 170         xmlXPathObjectPtr xpathObj = NULL;
 171
 172         LTTNG_ASSERT(xml_path);
 173         LTTNG_ASSERT(xpath);
 174
 175         /* Parse the xml file */
 176         doc = xmlParseFile(xml_path);
 177         if (!doc) {
 178                 fprintf(stderr, "ERR parsing: xml file invalid \"%s\"\n", xml_path);
 179                 return -1;
 180         }
 181
 182         /* Initialize a xpath context */
 183         xpathCtx = xmlXPathNewContext(doc);
 184         if (!xpathCtx) {
 185                 fprintf(stderr, "ERR: XPath context invalid\n");
 186                 xmlFreeDoc(doc);
 187                 return -1;
 188         }
 189
 190         /* Register the LTTng MI namespace */
 191         ret = register_lttng_namespace(xpathCtx);
 192         if (ret) {
 193                 fprintf(stderr, "ERR: Could not register lttng namespace\n");
 194                 xmlXPathFreeContext(xpathCtx);
 195                 xmlFreeDoc(doc);
 196                 return -1;
 197         }
 198
 199         /* Evaluate xpath expression */
 200         xpathObj = xmlXPathEvalExpression(xpath, xpathCtx);
 201         if (!xpathObj) {
 202                 fprintf(stderr, "ERR: invalid xpath expression \"%s\"\n", xpath);
 203                 xmlXPathFreeContext(xpathCtx);
 204                 xmlFreeDoc(doc);
 205                 return -1;
 206         }
 207
 208         /* Print results */
 209         if (print_xpath_nodes(doc, xpathObj->nodesetval, stdout)) {
 210                 xmlXPathFreeObject(xpathObj);
 211                 xmlXPathFreeContext(xpathCtx);
 212                 xmlFreeDoc(doc);
 213                 return -1;
 214         }
 215         if (node_exist && result) {
 216                 fprintf(stdout, "true\n");
 217         }
 218
 219         /* Cleanup */
 220         xmlXPathFreeObject(xpathObj);
 221         xmlXPathFreeContext(xpathCtx);
 222         xmlFreeDoc(doc);
 223
 224         return 0;
 225 }
 226
 227 int main(int argc, char **argv)
 228 {
 229         int opt;
 230
 231         /* Parse command line and process file */
 232         while ((opt = getopt(argc, argv, "ve")) != -1) {
 233                 switch (opt) {
 234                 case 'v':
 235                         opt_verbose = 1;
 236                         break;
 237                 case 'e':
 238                         node_exist = 1;
 239                         break;
 240                 default:
 241                         abort();
 242                 }
 243         }
 244
 245         if (!(optind + 1 < argc)) {
 246                 fprintf(stderr, "ERR:%s\n", "Arguments missing");
 247                 return -1;
 248         }
 249
 250         /* Init libxml */
 251         xmlInitParser();
 252         xmlKeepBlanksDefault(0);
 253         if (access(argv[optind], F_OK)) {
 254                 fprintf(stderr, "ERR:%s\n", "Xml path not valid");
 255                 return -1;
 256         }
 257         /* Do the main job */
 258         if (extract_xpath(argv[optind], (xmlChar *)argv[optind+1])) {
 259                 return -1;
 260         }
 261
 262         /* Shutdown libxml */
 263         xmlCleanupParser();
 264
 265         return 0;
 266 }
 267
 268 #else
 269 int main(void)
 270 {
 271         fprintf(stderr, "XPath support not compiled in\n");
 272         return -1;
 273 }
 274 #endif