1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.haxx.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 ***************************************************************************/
22 /* <DESC>
23 * Stream-parse a document using the streaming Expat parser.
24 * </DESC>
25 */
26 /* Written by David Strauss
27 *
28 * Expat => http://www.libexpat.org/
29 *
30 * gcc -Wall -I/usr/local/include xmlstream.c -lcurl -lexpat -o xmlstream
31 *
32 */
33
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <assert.h>
38
39 #include <expat.h>
40 #include <curl/curl.h>
41
42 struct MemoryStruct {
43 char *memory;
44 size_t size;
45 };
46
47 struct ParserStruct {
48 int ok;
49 size_t tags;
50 size_t depth;
51 struct MemoryStruct characters;
52 };
53
startElement(void * userData,const XML_Char * name,const XML_Char ** atts)54 static void startElement(void *userData, const XML_Char *name,
55 const XML_Char **atts)
56 {
57 struct ParserStruct *state = (struct ParserStruct *) userData;
58 state->tags++;
59 state->depth++;
60
61 /* Get a clean slate for reading in character data. */
62 free(state->characters.memory);
63 state->characters.memory = NULL;
64 state->characters.size = 0;
65 }
66
characterDataHandler(void * userData,const XML_Char * s,int len)67 static void characterDataHandler(void *userData, const XML_Char *s, int len)
68 {
69 struct ParserStruct *state = (struct ParserStruct *) userData;
70 struct MemoryStruct *mem = &state->characters;
71
72 mem->memory = realloc(mem->memory, mem->size + len + 1);
73 if(mem->memory == NULL) {
74 /* Out of memory. */
75 fprintf(stderr, "Not enough memory (realloc returned NULL).\n");
76 state->ok = 0;
77 return;
78 }
79
80 memcpy(&(mem->memory[mem->size]), s, len);
81 mem->size += len;
82 mem->memory[mem->size] = 0;
83 }
84
endElement(void * userData,const XML_Char * name)85 static void endElement(void *userData, const XML_Char *name)
86 {
87 struct ParserStruct *state = (struct ParserStruct *) userData;
88 state->depth--;
89
90 printf("%5lu %10lu %s\n", state->depth, state->characters.size, name);
91 }
92
parseStreamCallback(void * contents,size_t length,size_t nmemb,void * userp)93 static size_t parseStreamCallback(void *contents, size_t length, size_t nmemb,
94 void *userp)
95 {
96 XML_Parser parser = (XML_Parser) userp;
97 size_t real_size = length * nmemb;
98 struct ParserStruct *state = (struct ParserStruct *) XML_GetUserData(parser);
99
100 /* Only parse if we're not already in a failure state. */
101 if(state->ok && XML_Parse(parser, contents, real_size, 0) == 0) {
102 int error_code = XML_GetErrorCode(parser);
103 fprintf(stderr, "Parsing response buffer of length %lu failed"
104 " with error code %d (%s).\n",
105 real_size, error_code, XML_ErrorString(error_code));
106 state->ok = 0;
107 }
108
109 return real_size;
110 }
111
main(void)112 int main(void)
113 {
114 CURL *curl_handle;
115 CURLcode res;
116 XML_Parser parser;
117 struct ParserStruct state;
118
119 /* Initialize the state structure for parsing. */
120 memset(&state, 0, sizeof(struct ParserStruct));
121 state.ok = 1;
122
123 /* Initialize a namespace-aware parser. */
124 parser = XML_ParserCreateNS(NULL, '\0');
125 XML_SetUserData(parser, &state);
126 XML_SetElementHandler(parser, startElement, endElement);
127 XML_SetCharacterDataHandler(parser, characterDataHandler);
128
129 /* Initialize a libcurl handle. */
130 curl_global_init(CURL_GLOBAL_ALL ^ CURL_GLOBAL_SSL);
131 curl_handle = curl_easy_init();
132 curl_easy_setopt(curl_handle, CURLOPT_URL,
133 "http://www.w3schools.com/xml/simple.xml");
134 curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, parseStreamCallback);
135 curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)parser);
136
137 printf("Depth Characters Closing Tag\n");
138
139 /* Perform the request and any follow-up parsing. */
140 res = curl_easy_perform(curl_handle);
141 if(res != CURLE_OK) {
142 fprintf(stderr, "curl_easy_perform() failed: %s\n",
143 curl_easy_strerror(res));
144 }
145 else if(state.ok) {
146 /* Expat requires one final call to finalize parsing. */
147 if(XML_Parse(parser, NULL, 0, 1) == 0) {
148 int error_code = XML_GetErrorCode(parser);
149 fprintf(stderr, "Finalizing parsing failed with error code %d (%s).\n",
150 error_code, XML_ErrorString(error_code));
151 }
152 else {
153 printf(" --------------\n");
154 printf(" %lu tags total\n", state.tags);
155 }
156 }
157
158 /* Clean up. */
159 free(state.characters.memory);
160 XML_ParserFree(parser);
161 curl_easy_cleanup(curl_handle);
162 curl_global_cleanup();
163
164 return 0;
165 }
166