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
22static const char *result = "<list><people>a</people><people>b</people></list>";
23static const char *cur = NULL;
24static 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 */
34static int
35sqlMatch(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 */
50static void *
51sqlOpen(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 */
67static int
68sqlClose(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 */
85static int
86sqlRead(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
98const 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
104int 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
162int main(void) {
163    fprintf(stderr, "XInclude support not compiled in\n");
164    exit(1);
165}
166#endif
167