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