1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2015, 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 mem->memory = realloc(mem->memory, mem->size + realsize + 1);
46 if(mem->memory == NULL) {
47 /* out of memory! */
48 printf("not enough memory (realloc returned NULL)\n");
49 return 0;
50 }
51
52 memcpy(&(mem->memory[mem->size]), contents, realsize);
53 mem->size += realsize;
54 mem->memory[mem->size] = 0;
55
56 return realsize;
57 }
58
main(void)59 int main(void)
60 {
61 CURL *curl_handle;
62 CURLcode res;
63
64 struct MemoryStruct chunk;
65
66 chunk.memory = malloc(1); /* will be grown as needed by the realloc above */
67 chunk.size = 0; /* no data at this point */
68
69 curl_global_init(CURL_GLOBAL_ALL);
70
71 /* init the curl session */
72 curl_handle = curl_easy_init();
73
74 /* specify URL to get */
75 curl_easy_setopt(curl_handle, CURLOPT_URL, "http://www.example.com/");
76
77 /* send all data to this function */
78 curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
79
80 /* we pass our 'chunk' struct to the callback function */
81 curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
82
83 /* some servers don't like requests that are made without a user-agent
84 field, so we provide one */
85 curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
86
87 /* get it! */
88 res = curl_easy_perform(curl_handle);
89
90 /* check for errors */
91 if(res != CURLE_OK) {
92 fprintf(stderr, "curl_easy_perform() failed: %s\n",
93 curl_easy_strerror(res));
94 }
95 else {
96 /*
97 * Now, our chunk.memory points to a memory block that is chunk.size
98 * bytes big and contains the remote file.
99 *
100 * Do something nice with it!
101 */
102
103 printf("%lu bytes retrieved\n", (long)chunk.size);
104 }
105
106 /* cleanup curl stuff */
107 curl_easy_cleanup(curl_handle);
108
109 free(chunk.memory);
110
111 /* we're done with libcurl, so clean it up */
112 curl_global_cleanup();
113
114 return 0;
115 }
116