multi-single.c revision 9bd90e6e25f1e55f50201c87a1b5837de7e5b64a 
1/*****************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 *
9 * This is a very simple example using the multi interface.
10 */
11
12#include <stdio.h>
13#include <string.h>
14
15/* somewhat unix-specific */
16#include <sys/time.h>
17#include <unistd.h>
18
19/* curl stuff */
20#include <curl/curl.h>
21
22/*
23 * Simply download a HTTP file.
24 */
25int main(int argc, char **argv)
26{
27  CURL *http_handle;
28  CURLM *multi_handle;
29
30  int still_running; /* keep number of running handles */
31
32  http_handle = curl_easy_init();
33
34  /* set the options (I left out a few, you'll get the point anyway) */
35  curl_easy_setopt(http_handle, CURLOPT_URL, "http://www.example.com/");
36
37  /* init a multi stack */
38  multi_handle = curl_multi_init();
39
40  /* add the individual transfers */
41  curl_multi_add_handle(multi_handle, http_handle);
42
43  /* we start some action by calling perform right away */
44  curl_multi_perform(multi_handle, &still_running);
45
46  while(still_running) {
47    struct timeval timeout;
48    int rc; /* select() return code */
49
50    fd_set fdread;
51    fd_set fdwrite;
52    fd_set fdexcep;
53    int maxfd = -1;
54
55    long curl_timeo = -1;
56
57    FD_ZERO(&fdread);
58    FD_ZERO(&fdwrite);
59    FD_ZERO(&fdexcep);
60
61    /* set a suitable timeout to play around with */
62    timeout.tv_sec = 1;
63    timeout.tv_usec = 0;
64
65    curl_multi_timeout(multi_handle, &curl_timeo);
66    if(curl_timeo >= 0) {
67      timeout.tv_sec = curl_timeo / 1000;
68      if(timeout.tv_sec > 1)
69        timeout.tv_sec = 1;
70      else
71        timeout.tv_usec = (curl_timeo % 1000) * 1000;
72    }
73
74    /* get file descriptors from the transfers */
75    curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
76
77    /* In a real-world program you OF COURSE check the return code of the
78       function calls.  On success, the value of maxfd is guaranteed to be
79       greater or equal than -1.  We call select(maxfd + 1, ...), specially in
80       case of (maxfd == -1), we call select(0, ...), which is basically equal
81       to sleep. */
82
83    rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);
84
85    switch(rc) {
86    case -1:
87      /* select error */
88      still_running = 0;
89      printf("select() returns error, this is badness\n");
90      break;
91    case 0:
92    default:
93      /* timeout or readable/writable sockets */
94      curl_multi_perform(multi_handle, &still_running);
95      break;
96    }
97  }
98
99  curl_multi_cleanup(multi_handle);
100
101  curl_easy_cleanup(http_handle);
102
103  return 0;
104}
105