kc3-lang/libxml2/doc/examples/io1.c

• Show log

  Commit

• Hash : fc119e32
  Author :
  Date : 2023-04-30T15:28:12
  

  examples: Don't call xmlCleanupParser and xmlMemoryDump
  
  xmlCleanupParser is dangerous and shouldn't be called in most cases.
  Being part of the examples led many people to use it incorrectly.
  
  xmlMemoryDump is an obsolete way to test for memory leaks.
  

Download

• doc/examples/io1.c

• /**
   * section: InputOutput
   * synopsis: Example of custom Input/Output
   * purpose: Demonstrate the use of xmlRegisterInputCallbacks
   *          to build a custom I/O layer, this is used in an
   *          XInclude method context to show how dynamic document can
   *          be built in a clean way.
   * usage: io1
   * test: io1 > io1.tmp && diff io1.tmp $(srcdir)/io1.res
   * author: Daniel Veillard
   * copy: see Copyright for the status of this software.
   */
  
  #include <stdio.h>
  #include <string.h>
  #include <libxml/parser.h>
  #include <libxml/tree.h>
  #include <libxml/xinclude.h>
  #include <libxml/xmlIO.h>
  
  #ifdef LIBXML_XINCLUDE_ENABLED
  static const char *result = "<list><people>a</people><people>b</people></list>";
  static const char *cur = NULL;
  static int rlen;
  
  /**
   * sqlMatch:
   * @URI: an URI to test
   *
   * Check for an sql: query
   *
   * Returns 1 if yes and 0 if another Input module should be used
   */
  static int
  sqlMatch(const char * URI) {
      if ((URI != NULL) && (!strncmp(URI, "sql:", 4)))
          return(1);
      return(0);
  }
  
  /**
   * sqlOpen:
   * @URI: an URI to test
   *
   * Return a pointer to the sql: query handler, in this example simply
   * the current pointer...
   *
   * Returns an Input context or NULL in case or error
   */
  static void *
  sqlOpen(const char * URI) {
      if ((URI == NULL) || (strncmp(URI, "sql:", 4)))
          return(NULL);
      cur = result;
      rlen = strlen(result);
      return((void *) cur);
  }
  
  /**
   * sqlClose:
   * @context: the read context
   *
   * Close the sql: query handler
   *
   * Returns 0 or -1 in case of error
   */
  static int
  sqlClose(void * context) {
      if (context == NULL) return(-1);
      cur = NULL;
      rlen = 0;
      return(0);
  }
  
  /**
   * sqlRead:
   * @context: the read context
   * @buffer: where to store data
   * @len: number of bytes to read
   *
   * Implement an sql: query read.
   *
   * Returns the number of bytes read or -1 in case of error
   */
  static int
  sqlRead(void * context, char * buffer, int len) {
     const char *ptr = (const char *) context;
  
     if ((context == NULL) || (buffer == NULL) || (len < 0))
         return(-1);
  
     if (len > rlen) len = rlen;
     memcpy(buffer, ptr, len);
     rlen -= len;
     return(len);
  }
  
  const char *include = "<?xml version='1.0'?>\n\
  <document xmlns:xi=\"http://www.w3.org/2003/XInclude\">\n\
    <p>List of people:</p>\n\
    <xi:include href=\"sql:select_name_from_people\"/>\n\
  </document>\n";
  
  int main(void) {
      xmlDocPtr doc;
  
      /*
       * this initialize the library and check potential ABI mismatches
       * between the version it was compiled for and the actual shared
       * library used.
       */
      LIBXML_TEST_VERSION
  
      /*
       * register the new I/O handlers
       */
      if (xmlRegisterInputCallbacks(sqlMatch, sqlOpen, sqlRead, sqlClose) < 0) {
          fprintf(stderr, "failed to register SQL handler\n");
  	exit(1);
      }
      /*
       * parse include into a document
       */
      doc = xmlReadMemory(include, strlen(include), "include.xml", NULL, 0);
      if (doc == NULL) {
          fprintf(stderr, "failed to parse the including file\n");
  	exit(1);
      }
  
      /*
       * apply the XInclude process, this should trigger the I/O just
       * registered.
       */
      if (xmlXIncludeProcess(doc) <= 0) {
          fprintf(stderr, "XInclude processing failed\n");
  	exit(1);
      }
  
  #ifdef LIBXML_OUTPUT_ENABLED
      /*
       * save the output for checking to stdout
       */
      xmlDocDump(stdout, doc);
  #endif
  
      /*
       * Free the document
       */
      xmlFreeDoc(doc);
  
      return(0);
  }
  #else
  int main(void) {
      fprintf(stderr, "XInclude support not compiled in\n");
      return(0);
  }
  #endif
  

Download