Annotation of embedaddon/curl/docs/examples/xmlstream.c, revision 1.1
1.1 ! misho 1: /***************************************************************************
! 2: * _ _ ____ _
! 3: * Project ___| | | | _ \| |
! 4: * / __| | | | |_) | |
! 5: * | (__| |_| | _ <| |___
! 6: * \___|\___/|_| \_\_____|
! 7: *
! 8: * Copyright (C) 1998 - 2018, 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 => https://libexpat.github.io/
! 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:
! 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:
! 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: char *ptr = realloc(mem->memory, mem->size + len + 1);
! 73: if(!ptr) {
! 74: /* Out of memory. */
! 75: fprintf(stderr, "Not enough memory (realloc returned NULL).\n");
! 76: state->ok = 0;
! 77: return;
! 78: }
! 79:
! 80: mem->memory = ptr;
! 81: memcpy(&(mem->memory[mem->size]), s, len);
! 82: mem->size += len;
! 83: mem->memory[mem->size] = 0;
! 84: }
! 85:
! 86: static void endElement(void *userData, const XML_Char *name)
! 87: {
! 88: struct ParserStruct *state = (struct ParserStruct *) userData;
! 89: state->depth--;
! 90:
! 91: printf("%5lu %10lu %s\n", state->depth, state->characters.size, name);
! 92: }
! 93:
! 94: static size_t parseStreamCallback(void *contents, size_t length, size_t nmemb,
! 95: void *userp)
! 96: {
! 97: XML_Parser parser = (XML_Parser) userp;
! 98: size_t real_size = length * nmemb;
! 99: struct ParserStruct *state = (struct ParserStruct *) XML_GetUserData(parser);
! 100:
! 101: /* Only parse if we're not already in a failure state. */
! 102: if(state->ok && XML_Parse(parser, contents, real_size, 0) == 0) {
! 103: int error_code = XML_GetErrorCode(parser);
! 104: fprintf(stderr, "Parsing response buffer of length %lu failed"
! 105: " with error code %d (%s).\n",
! 106: real_size, error_code, XML_ErrorString(error_code));
! 107: state->ok = 0;
! 108: }
! 109:
! 110: return real_size;
! 111: }
! 112:
! 113: int main(void)
! 114: {
! 115: CURL *curl_handle;
! 116: CURLcode res;
! 117: XML_Parser parser;
! 118: struct ParserStruct state;
! 119:
! 120: /* Initialize the state structure for parsing. */
! 121: memset(&state, 0, sizeof(struct ParserStruct));
! 122: state.ok = 1;
! 123:
! 124: /* Initialize a namespace-aware parser. */
! 125: parser = XML_ParserCreateNS(NULL, '\0');
! 126: XML_SetUserData(parser, &state);
! 127: XML_SetElementHandler(parser, startElement, endElement);
! 128: XML_SetCharacterDataHandler(parser, characterDataHandler);
! 129:
! 130: /* Initialize a libcurl handle. */
! 131: curl_global_init(CURL_GLOBAL_DEFAULT);
! 132: curl_handle = curl_easy_init();
! 133: curl_easy_setopt(curl_handle, CURLOPT_URL,
! 134: "https://www.w3schools.com/xml/simple.xml");
! 135: curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, parseStreamCallback);
! 136: curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)parser);
! 137:
! 138: printf("Depth Characters Closing Tag\n");
! 139:
! 140: /* Perform the request and any follow-up parsing. */
! 141: res = curl_easy_perform(curl_handle);
! 142: if(res != CURLE_OK) {
! 143: fprintf(stderr, "curl_easy_perform() failed: %s\n",
! 144: curl_easy_strerror(res));
! 145: }
! 146: else if(state.ok) {
! 147: /* Expat requires one final call to finalize parsing. */
! 148: if(XML_Parse(parser, NULL, 0, 1) == 0) {
! 149: int error_code = XML_GetErrorCode(parser);
! 150: fprintf(stderr, "Finalizing parsing failed with error code %d (%s).\n",
! 151: error_code, XML_ErrorString(error_code));
! 152: }
! 153: else {
! 154: printf(" --------------\n");
! 155: printf(" %lu tags total\n", state.tags);
! 156: }
! 157: }
! 158:
! 159: /* Clean up. */
! 160: free(state.characters.memory);
! 161: XML_ParserFree(parser);
! 162: curl_easy_cleanup(curl_handle);
! 163: curl_global_cleanup();
! 164:
! 165: return 0;
! 166: }
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