1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2013, 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 http://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/* Stream-parse a document using the streaming Expat parser.
23 * Written by David Strauss
24 *
25 * Expat => http://www.libexpat.org/
26 *
27 * gcc -Wall -I/usr/local/include xmlstream.c -lcurl -lexpat -o xmlstream
28 *
29 */
30
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <assert.h>
35
36#include <expat.h>
37#include <curl/curl.h>
38
39struct MemoryStruct {
40  char *memory;
41  size_t size;
42};
43
44struct ParserStruct {
45  int ok;
46  size_t tags;
47  size_t depth;
48  struct MemoryStruct characters;
49};
50
51static void startElement(void *userData, const XML_Char *name, const XML_Char **atts)
52{
53  struct ParserStruct *state = (struct ParserStruct *) userData;
54  state->tags++;
55  state->depth++;
56
57  /* Get a clean slate for reading in character data. */
58  free(state->characters.memory);
59  state->characters.memory = NULL;
60  state->characters.size = 0;
61}
62
63static void characterDataHandler(void *userData, const XML_Char *s, int len)
64{
65  struct ParserStruct *state = (struct ParserStruct *) userData;
66  struct MemoryStruct *mem = &state->characters;
67
68  mem->memory = realloc(mem->memory, mem->size + len + 1);
69  if(mem->memory == NULL) {
70    /* Out of memory. */
71    fprintf(stderr, "Not enough memory (realloc returned NULL).\n");
72    state->ok = 0;
73    return;
74  }
75
76  memcpy(&(mem->memory[mem->size]), s, len);
77  mem->size += len;
78  mem->memory[mem->size] = 0;
79}
80
81static void endElement(void *userData, const XML_Char *name)
82{
83  struct ParserStruct *state = (struct ParserStruct *) userData;
84  state->depth--;
85
86  printf("%5lu   %10lu   %s\n", state->depth, state->characters.size, name);
87}
88
89static size_t parseStreamCallback(void *contents, size_t length, size_t nmemb, void *userp)
90{
91  XML_Parser parser = (XML_Parser) userp;
92  size_t real_size = length * nmemb;
93  struct ParserStruct *state = (struct ParserStruct *) XML_GetUserData(parser);
94
95  /* Only parse if we're not already in a failure state. */
96  if (state->ok && XML_Parse(parser, contents, real_size, 0) == 0) {
97    int error_code = XML_GetErrorCode(parser);
98    fprintf(stderr, "Parsing response buffer of length %lu failed with error code %d (%s).\n",
99            real_size, error_code, XML_ErrorString(error_code));
100    state->ok = 0;
101  }
102
103  return real_size;
104}
105
106int main(void)
107{
108  CURL *curl_handle;
109  CURLcode res;
110  XML_Parser parser;
111  struct ParserStruct state;
112
113  /* Initialize the state structure for parsing. */
114  memset(&state, 0, sizeof(struct ParserStruct));
115  state.ok = 1;
116
117  /* Initialize a namespace-aware parser. */
118  parser = XML_ParserCreateNS(NULL, '\0');
119  XML_SetUserData(parser, &state);
120  XML_SetElementHandler(parser, startElement, endElement);
121  XML_SetCharacterDataHandler(parser, characterDataHandler);
122
123  /* Initalize a libcurl handle. */
124  curl_global_init(CURL_GLOBAL_ALL ^ CURL_GLOBAL_SSL);
125  curl_handle = curl_easy_init();
126  curl_easy_setopt(curl_handle, CURLOPT_URL, "http://www.w3schools.com/xml/simple.xml");
127  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, parseStreamCallback);
128  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)parser);
129
130  printf("Depth   Characters   Closing Tag\n");
131
132  /* Perform the request and any follow-up parsing. */
133  res = curl_easy_perform(curl_handle);
134  if(res != CURLE_OK) {
135    fprintf(stderr, "curl_easy_perform() failed: %s\n",
136            curl_easy_strerror(res));
137  }
138  else if (state.ok) {
139    /* Expat requires one final call to finalize parsing. */
140    if (XML_Parse(parser, NULL, 0, 1) == 0) {
141      int error_code = XML_GetErrorCode(parser);
142      fprintf(stderr, "Finalizing parsing failed with error code %d (%s).\n",
143              error_code, XML_ErrorString(error_code));
144    }
145    else {
146      printf("                     --------------\n");
147      printf("                     %lu tags total\n", state.tags);
148    }
149  }
150
151  /* Clean up. */
152  free(state.characters.memory);
153  XML_ParserFree(parser);
154  curl_easy_cleanup(curl_handle);
155  curl_global_cleanup();
156
157  return 0;
158}
159