Current File : //opt/alt/libxml2/usr/share/doc/alt-libxml2-devel/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);
/*
* Cleanup function for the XML library.
*/
xmlCleanupParser();
/*
* this is to debug memory for regression tests
*/
xmlMemoryDump();
return(0);
}
#else
int main(void) {
fprintf(stderr, "XInclude support not compiled in\n");
return(0);
}
#endif
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