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

imap-multi.c

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/***************************************************************************
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 *
 * 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>
 * IMAP example using the multi interface
 * </DESC>
 */ 
 
#include <stdio.h>
#include <string.h>
#include <curl/curl.h>
 
/* This is a simple example showing how to fetch mail using libcurl's IMAP
 * capabilities. It builds on the imap-fetch.c example to demonstrate how to
 * use libcurl's multi interface.
 *
 * Note that this example requires libcurl 7.30.0 or above.
 */ 
 
#define MULTI_PERFORM_HANG_TIMEOUT 60 * 1000
 
static struct timeval tvnow(void)
{
  struct timeval now;
 
  /* time() returns the value of time in seconds since the epoch */ 
  now.tv_sec = (long)time(NULL);
  now.tv_usec = 0;
 
  return now;
}
 
static long tvdiff(struct timeval newer, struct timeval older)
{
  return (newer.tv_sec - older.tv_sec) * 1000 +
    (newer.tv_usec - older.tv_usec) / 1000;
}
 
int main(void)
{
  CURL *curl;
  CURLM *mcurl;
  int still_running = 1;
  struct timeval mp_start;
 
  curl_global_init(CURL_GLOBAL_DEFAULT);
 
  curl = curl_easy_init();
  if(!curl)
    return 1;
 
  mcurl = curl_multi_init();
  if(!mcurl)
    return 2;
 
  /* Set username and password */ 
  curl_easy_setopt(curl, CURLOPT_USERNAME, "user");
  curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");
 
  /* This will fetch message 1 from the user's inbox */ 
  curl_easy_setopt(curl, CURLOPT_URL, "imap://imap.example.com/INBOX/;UID=1");
 
  /* Tell the multi stack about our easy handle */ 
  curl_multi_add_handle(mcurl, curl);
 
  /* Record the start time which we can use later */ 
  mp_start = tvnow();
 
  /* We start some action by calling perform right away */ 
  curl_multi_perform(mcurl, &still_running);
 
  while(still_running) {
    struct timeval timeout;
    fd_set fdread;
    fd_set fdwrite;
    fd_set fdexcep;
    int maxfd = -1;
    int rc;
    CURLMcode mc; /* curl_multi_fdset() return code */ 
 
    long curl_timeo = -1;
 
    /* Initialise the file descriptors */ 
    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(mcurl, &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(mcurl, &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);
    }
 
    if(tvdiff(tvnow(), mp_start) > MULTI_PERFORM_HANG_TIMEOUT) {
      fprintf(stderr,
              "ABORTING: Since it seems that we would have run forever.\n");
      break;
    }
 
    switch(rc) {
    case -1:  /* select error */ 
      break;
    case 0:   /* timeout */ 
    default:  /* action */ 
      curl_multi_perform(mcurl, &still_running);
      break;
    }
  }
 
  /* Always cleanup */ 
  curl_multi_remove_handle(mcurl, curl);
  curl_multi_cleanup(mcurl);
  curl_easy_cleanup(curl);
  curl_global_cleanup();
 
  return 0;
}