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
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 
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