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
sqlMatch(const char * URI)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 *
sqlOpen(const char * URI)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
sqlClose(void * context)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
sqlRead(void * context,char * buffer,int len)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
main(void)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
main(void)162 int main(void) {
163 fprintf(stderr, "XInclude support not compiled in\n");
164 exit(1);
165 }
166 #endif
167