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      1 /***************************************************************************
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      5  *                            | (__| |_| |  _ <| |___
      6  *                             \___|\___/|_| \_\_____|
      7  *
      8  * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel (at) 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