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libxml2 2.9.1

    1: /**
    2:  * section: InputOutput
    3:  * synopsis: Example of custom Input/Output
    4:  * purpose: Demonstrate the use of xmlRegisterInputCallbacks
    5:  *          to build a custom I/O layer, this is used in an
    6:  *          XInclude method context to show how dynamic document can
    7:  *          be built in a clean way.
    8:  * usage: io1
    9:  * test: io1 > io1.tmp && diff io1.tmp $(srcdir)/io1.res
   10:  * author: Daniel Veillard
   11:  * copy: see Copyright for the status of this software.
   12:  */
   13: 
   14: #include <stdio.h>
   15: #include <string.h>
   16: #include <libxml/parser.h>
   17: #include <libxml/tree.h>
   18: #include <libxml/xinclude.h>
   19: #include <libxml/xmlIO.h>
   20: 
   21: #ifdef LIBXML_XINCLUDE_ENABLED
   22: static const char *result = "<list><people>a</people><people>b</people></list>";
   23: static const char *cur = NULL;
   24: static int rlen;
   25: 
   26: /**
   27:  * sqlMatch:
   28:  * @URI: an URI to test
   29:  *
   30:  * Check for an sql: query
   31:  *
   32:  * Returns 1 if yes and 0 if another Input module should be used
   33:  */
   34: static int
   35: sqlMatch(const char * URI) {
   36:     if ((URI != NULL) && (!strncmp(URI, "sql:", 4)))
   37:         return(1);
   38:     return(0);
   39: }
   40: 
   41: /**
   42:  * sqlOpen:
   43:  * @URI: an URI to test
   44:  *
   45:  * Return a pointer to the sql: query handler, in this example simply
   46:  * the current pointer...
   47:  *
   48:  * Returns an Input context or NULL in case or error
   49:  */
   50: static void *
   51: sqlOpen(const char * URI) {
   52:     if ((URI == NULL) || (strncmp(URI, "sql:", 4)))
   53:         return(NULL);
   54:     cur = result;
   55:     rlen = strlen(result);
   56:     return((void *) cur);
   57: }
   58: 
   59: /**
   60:  * sqlClose:
   61:  * @context: the read context
   62:  *
   63:  * Close the sql: query handler
   64:  *
   65:  * Returns 0 or -1 in case of error
   66:  */
   67: static int
   68: sqlClose(void * context) {
   69:     if (context == NULL) return(-1);
   70:     cur = NULL;
   71:     rlen = 0;
   72:     return(0);
   73: }
   74: 
   75: /**
   76:  * sqlRead:
   77:  * @context: the read context
   78:  * @buffer: where to store data
   79:  * @len: number of bytes to read
   80:  *
   81:  * Implement an sql: query read.
   82:  *
   83:  * Returns the number of bytes read or -1 in case of error
   84:  */
   85: static int
   86: sqlRead(void * context, char * buffer, int len) {
   87:    const char *ptr = (const char *) context;
   88: 
   89:    if ((context == NULL) || (buffer == NULL) || (len < 0))
   90:        return(-1);
   91: 
   92:    if (len > rlen) len = rlen;
   93:    memcpy(buffer, ptr, len);
   94:    rlen -= len;
   95:    return(len);
   96: }
   97: 
   98: const char *include = "<?xml version='1.0'?>\n\
   99: <document xmlns:xi=\"http://www.w3.org/2003/XInclude\">\n\
  100:   <p>List of people:</p>\n\
  101:   <xi:include href=\"sql:select_name_from_people\"/>\n\
  102: </document>\n";
  103: 
  104: int main(void) {
  105:     xmlDocPtr doc;
  106: 
  107:     /*
  108:      * this initialize the library and check potential ABI mismatches
  109:      * between the version it was compiled for and the actual shared
  110:      * library used.
  111:      */
  112:     LIBXML_TEST_VERSION
  113: 
  114:     /*
  115:      * register the new I/O handlers
  116:      */
  117:     if (xmlRegisterInputCallbacks(sqlMatch, sqlOpen, sqlRead, sqlClose) < 0) {
  118:         fprintf(stderr, "failed to register SQL handler\n");
  119: 	exit(1);
  120:     }
  121:     /*
  122:      * parse include into a document
  123:      */
  124:     doc = xmlReadMemory(include, strlen(include), "include.xml", NULL, 0);
  125:     if (doc == NULL) {
  126:         fprintf(stderr, "failed to parse the including file\n");
  127: 	exit(1);
  128:     }
  129: 
  130:     /*
  131:      * apply the XInclude process, this should trigger the I/O just
  132:      * registered.
  133:      */
  134:     if (xmlXIncludeProcess(doc) <= 0) {
  135:         fprintf(stderr, "XInclude processing failed\n");
  136: 	exit(1);
  137:     }
  138: 
  139: #ifdef LIBXML_OUTPUT_ENABLED
  140:     /*
  141:      * save the output for checking to stdout
  142:      */
  143:     xmlDocDump(stdout, doc);
  144: #endif
  145: 
  146:     /*
  147:      * Free the document
  148:      */
  149:     xmlFreeDoc(doc);
  150: 
  151:     /*
  152:      * Cleanup function for the XML library.
  153:      */
  154:     xmlCleanupParser();
  155:     /*
  156:      * this is to debug memory for regression tests
  157:      */
  158:     xmlMemoryDump();
  159:     return(0);
  160: }
  161: #else
  162: int main(void) {
  163:     fprintf(stderr, "XInclude support not compiled in\n");
  164:     exit(1);
  165: }
  166: #endif