curl / libcurl / API / Examples / multi-app.c

multi-app.c

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/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/ 
/* <DESC>
 * A basic application source code using the multi interface doing two
 * transfers in parallel.
 * </DESC>
 */ 
 
#include <stdio.h>
#include <string.h>
 
/* somewhat unix-specific */ 
#include <sys/time.h>
#include <unistd.h>
 
/* curl stuff */ 
#include <curl/curl.h>
 
/*
 * Download a HTTP file and upload an FTP file simultaneously.
 */ 
 
#define HANDLECOUNT 2    
#define HTTP_HANDLE 0    
#define FTP_HANDLE 1     
 
int main(void)
{
  CURL *handles[HANDLECOUNT];
  CURLM *multi_handle;
 
  int still_running; /* keep number of running handles */ 
  int i;
 
  CURLMsg *msg; /* for picking up messages with the transfer status */ 
  int msgs_left; /* how many messages are left */ 
 
  /* Allocate one CURL handle per transfer */ 
  for(i = 0; i<HANDLECOUNT; i++)
    handles[i] = curl_easy_init();
 
  /* set the options (I left out a few, you'll get the point anyway) */ 
  curl_easy_setopt(handles[HTTP_HANDLE], CURLOPT_URL, "http://example.com");
 
  curl_easy_setopt(handles[FTP_HANDLE], CURLOPT_URL, "ftp://example.com");
  curl_easy_setopt(handles[FTP_HANDLE], CURLOPT_UPLOAD, 1L);
 
  /* init a multi stack */ 
  multi_handle = curl_multi_init();
 
  /* add the individual transfers */ 
  for(i = 0; i<HANDLECOUNT; i++)
    curl_multi_add_handle(multi_handle, handles[i]);
 
  /* we start some action by calling perform right away */ 
  curl_multi_perform(multi_handle, &still_running);
 
  do {
    struct timeval timeout;
    int rc; /* select() return code */ 
    CURLMcode mc; /* curl_multi_fdset() return code */ 
 
    fd_set fdread;
    fd_set fdwrite;
    fd_set fdexcep;
    int maxfd = -1;
 
    long curl_timeo = -1;
 
    FD_ZERO(&fdread);
    FD_ZERO(&fdwrite);
    FD_ZERO(&fdexcep);
 
    /* set a suitable timeout to play around with */ 
    timeout.tv_sec = 1;
    timeout.tv_usec = 0;
 
    curl_multi_timeout(multi_handle, &curl_timeo);
    if(curl_timeo >= 0) {
      timeout.tv_sec = curl_timeo / 1000;
      if(timeout.tv_sec > 1)
        timeout.tv_sec = 1;
      else
        timeout.tv_usec = (curl_timeo % 1000) * 1000;
    }
 
    /* get file descriptors from the transfers */ 
    mc = curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
 
    if(mc != CURLM_OK) {
      fprintf(stderr, "curl_multi_fdset() failed, code %d.\n", mc);
      break;
    }
 
    /* On success the value of maxfd is guaranteed to be >= -1. We call
       select(maxfd + 1, ...); specially in case of (maxfd == -1) there are
       no fds ready yet so we call select(0, ...) --or Sleep() on Windows--
       to sleep 100ms, which is the minimum suggested value in the
       curl_multi_fdset() doc. */ 
 
    if(maxfd == -1) {
#ifdef _WIN32
      Sleep(100);
      rc = 0;
#else
      /* Portable sleep for platforms other than Windows. */ 
      struct timeval wait = { 0, 100 * 1000 }; /* 100ms */ 
      rc = select(0, NULL, NULL, NULL, &wait);
#endif
    }
    else {
      /* Note that on some platforms 'timeout' may be modified by select().
         If you need access to the original value save a copy beforehand. */ 
      rc = select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
    }
 
    switch(rc) {
    case -1:
      /* select error */ 
      break;
    case 0: /* timeout */ 
    default: /* action */ 
      curl_multi_perform(multi_handle, &still_running);
      break;
    }
  } while(still_running);
 
  /* See how the transfers went */ 
  while((msg = curl_multi_info_read(multi_handle, &msgs_left))) {
    if(msg->msg == CURLMSG_DONE) {
      int idx, found = 0;
 
      /* Find out which handle this message is about */ 
      for(idx = 0; idx<HANDLECOUNT; idx++) {
        found = (msg->easy_handle == handles[idx]);
        if(found)
          break;
      }
 
      switch(idx) {
      case HTTP_HANDLE:
        printf("HTTP transfer completed with status %d\n", msg->data.result);
        break;
      case FTP_HANDLE:
        printf("FTP transfer completed with status %d\n", msg->data.result);
        break;
      }
    }
  }
 
  curl_multi_cleanup(multi_handle);
 
  /* Free the CURL handles */ 
  for(i = 0; i<HANDLECOUNT; i++)
    curl_easy_cleanup(handles[i]);
 
  return 0;
}