1  /**
       2   * section: Parsing
       3   * synopsis: Parse an XML document chunk by chunk to a tree and free it
       4   * purpose: Demonstrate the use of xmlCreatePushParserCtxt() and
       5   *          xmlParseChunk() to read an XML file progressively
       6   *          into a tree and xmlFreeDoc() to free the resulting tree
       7   * usage: parse4 test3.xml
       8   * test: parse4 test3.xml
       9   * author: Daniel Veillard
      10   * copy: see Copyright for the status of this software.
      11   */
      12  
      13  #include <stdio.h>
      14  #include <libxml/parser.h>
      15  #include <libxml/tree.h>
      16  
      17  #ifdef LIBXML_PUSH_ENABLED
      18  static FILE *desc;
      19  
      20  /**
      21   * readPacket:
      22   * @mem: array to store the packet
      23   * @size: the packet size
      24   *
      25   * read at most @size bytes from the document and store it in @mem
      26   *
      27   * Returns the number of bytes read
      28   */
      29  static int
      30  readPacket(char *mem, int size) {
      31      int res;
      32  
      33      res = fread(mem, 1, size, desc);
      34      return(res);
      35  }
      36  
      37  /**
      38   * example4Func:
      39   * @filename: a filename or an URL
      40   *
      41   * Parse the resource and free the resulting tree
      42   */
      43  static void
      44  example4Func(const char *filename) {
      45      xmlParserCtxtPtr ctxt;
      46      char chars[4];
      47      xmlDocPtr doc; /* the resulting document tree */
      48      int res;
      49  
      50      /*
      51       * Read a few first byte to check the input used for the
      52       * encoding detection at the parser level.
      53       */
      54      res = readPacket(chars, 4);
      55      if (res <= 0) {
      56          fprintf(stderr, "Failed to parse %s\n", filename);
      57  	return;
      58      }
      59  
      60      /*
      61       * Create a progressive parsing context, the 2 first arguments
      62       * are not used since we want to build a tree and not use a SAX
      63       * parsing interface. We also pass the first bytes of the document
      64       * to allow encoding detection when creating the parser but this
      65       * is optional.
      66       */
      67      ctxt = xmlCreatePushParserCtxt(NULL, NULL,
      68                                     chars, res, filename);
      69      if (ctxt == NULL) {
      70          fprintf(stderr, "Failed to create parser context !\n");
      71  	return;
      72      }
      73  
      74      /*
      75       * loop on the input getting the document data, of course 4 bytes
      76       * at a time is not realistic but allows to verify testing on small
      77       * documents.
      78       */
      79      while ((res = readPacket(chars, 4)) > 0) {
      80          xmlParseChunk(ctxt, chars, res, 0);
      81      }
      82  
      83      /*
      84       * there is no more input, indicate the parsing is finished.
      85       */
      86      xmlParseChunk(ctxt, chars, 0, 1);
      87  
      88      /*
      89       * collect the document back and if it was wellformed
      90       * and destroy the parser context.
      91       */
      92      doc = ctxt->myDoc;
      93      res = ctxt->wellFormed;
      94      xmlFreeParserCtxt(ctxt);
      95  
      96      if (!res) {
      97          fprintf(stderr, "Failed to parse %s\n", filename);
      98      }
      99  
     100      /*
     101       * since we don't use the document, destroy it now.
     102       */
     103      xmlFreeDoc(doc);
     104  }
     105  
     106  int main(int argc, char **argv) {
     107      if (argc != 2)
     108          return(1);
     109  
     110      /*
     111       * this initialize the library and check potential ABI mismatches
     112       * between the version it was compiled for and the actual shared
     113       * library used.
     114       */
     115      LIBXML_TEST_VERSION
     116  
     117      /*
     118       * simulate a progressive parsing using the input file.
     119       */
     120      desc = fopen(argv[1], "rb");
     121      if (desc != NULL) {
     122  	example4Func(argv[1]);
     123  	fclose(desc);
     124      } else {
     125          fprintf(stderr, "Failed to parse %s\n", argv[1]);
     126      }
     127  
     128      return(0);
     129  }
     130  #else /* ! LIBXML_PUSH_ENABLED */
     131  int main(void) {
     132      fprintf(stderr, "Library not compiled with push parser support\n");
     133      return(0);
     134  }
     135  #endif