1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 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.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 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24/* <DESC>
25 * Shows how the write callback function can be used to download data into a
26 * chunk of memory instead of storing it in a file.
27 * </DESC>
28 */
29
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33
34#include <curl/curl.h>
35
36struct MemoryStruct {
37  char *memory;
38  size_t size;
39};
40
41static size_t
42WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
43{
44  size_t realsize = size * nmemb;
45  struct MemoryStruct *mem = (struct MemoryStruct *)userp;
46
47  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
48  if(!ptr) {
49    /* out of memory! */
50    printf("not enough memory (realloc returned NULL)\n");
51    return 0;
52  }
53
54  mem->memory = ptr;
55  memcpy(&(mem->memory[mem->size]), contents, realsize);
56  mem->size += realsize;
57  mem->memory[mem->size] = 0;
58
59  return realsize;
60}
61
62int main(void)
63{
64  CURL *curl_handle;
65  CURLcode res;
66
67  struct MemoryStruct chunk;
68
69  chunk.memory = malloc(1);  /* will be grown as needed by the realloc above */
70  chunk.size = 0;    /* no data at this point */
71
72  curl_global_init(CURL_GLOBAL_ALL);
73
74  /* init the curl session */
75  curl_handle = curl_easy_init();
76
77  /* specify URL to get */
78  curl_easy_setopt(curl_handle, CURLOPT_URL, "https://www.example.com/");
79
80  /* send all data to this function  */
81  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
82
83  /* we pass our 'chunk' struct to the callback function */
84  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
85
86  /* some servers do not like requests that are made without a user-agent
87     field, so we provide one */
88  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
89
90  /* get it! */
91  res = curl_easy_perform(curl_handle);
92
93  /* check for errors */
94  if(res != CURLE_OK) {
95    fprintf(stderr, "curl_easy_perform() failed: %s\n",
96            curl_easy_strerror(res));
97  }
98  else {
99    /*
100     * Now, our chunk.memory points to a memory block that is chunk.size
101     * bytes big and contains the remote file.
102     *
103     * Do something nice with it!
104     */
105
106    printf("%lu bytes retrieved\n", (unsigned long)chunk.size);
107  }
108
109  /* cleanup curl stuff */
110  curl_easy_cleanup(curl_handle);
111
112  free(chunk.memory);
113
114  /* we are done with libcurl, so clean it up */
115  curl_global_cleanup();
116
117  return 0;
118}
119