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