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      1 /***************************************************************************
      2  *                                  _   _ ____  _
      3  *  Project                     ___| | | |  _ \| |
      4  *                             / __| | | | |_) | |
      5  *                            | (__| |_| |  _ <| |___
      6  *                             \___|\___/|_| \_\_____|
      7  *
      8  * Copyright (C) 1998 - 2016, 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  * using the multi interface to do a single download
     24  * </DESC>
     25  */
     26 
     27 #include <stdio.h>
     28 #include <string.h>
     29 
     30 /* somewhat unix-specific */
     31 #include <sys/time.h>
     32 #include <unistd.h>
     33 
     34 /* curl stuff */
     35 #include <curl/curl.h>
     36 
     37 #ifdef _WIN32
     38 #define WAITMS(x) Sleep(x)
     39 #else
     40 /* Portable sleep for platforms other than Windows. */
     41 #define WAITMS(x)                               \
     42   struct timeval wait = { 0, (x) * 1000 };      \
     43   (void)select(0, NULL, NULL, NULL, &wait);
     44 #endif
     45 
     46 /*
     47  * Simply download a HTTP file.
     48  */
     49 int main(void)
     50 {
     51   CURL *http_handle;
     52   CURLM *multi_handle;
     53 
     54   int still_running; /* keep number of running handles */
     55   int repeats = 0;
     56 
     57   curl_global_init(CURL_GLOBAL_DEFAULT);
     58 
     59   http_handle = curl_easy_init();
     60 
     61   /* set the options (I left out a few, you'll get the point anyway) */
     62   curl_easy_setopt(http_handle, CURLOPT_URL, "http://www.example.com/");
     63 
     64   /* init a multi stack */
     65   multi_handle = curl_multi_init();
     66 
     67   /* add the individual transfers */
     68   curl_multi_add_handle(multi_handle, http_handle);
     69 
     70   /* we start some action by calling perform right away */
     71   curl_multi_perform(multi_handle, &still_running);
     72 
     73   do {
     74     CURLMcode mc; /* curl_multi_wait() return code */
     75     int numfds;
     76 
     77     /* wait for activity, timeout or "nothing" */
     78     mc = curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
     79 
     80     if(mc != CURLM_OK) {
     81       fprintf(stderr, "curl_multi_wait() failed, code %d.\n", mc);
     82       break;
     83     }
     84 
     85     /* 'numfds' being zero means either a timeout or no file descriptors to
     86        wait for. Try timeout on first occurrence, then assume no file
     87        descriptors and no file descriptors to wait for means wait for 100
     88        milliseconds. */
     89 
     90     if(!numfds) {
     91       repeats++; /* count number of repeated zero numfds */
     92       if(repeats > 1) {
     93         WAITMS(100); /* sleep 100 milliseconds */
     94       }
     95     }
     96     else
     97       repeats = 0;
     98 
     99     curl_multi_perform(multi_handle, &still_running);
    100   } while(still_running);
    101 
    102   curl_multi_remove_handle(multi_handle, http_handle);
    103 
    104   curl_easy_cleanup(http_handle);
    105 
    106   curl_multi_cleanup(multi_handle);
    107 
    108   curl_global_cleanup();
    109 
    110   return 0;
    111 }
    112