examples: Added POP3 multi example

docs/examples/Makefile.inc

@@ -6,9 +6,10 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
   sendrecv httpcustomheader certinfo chkspeed ftpgetinfo ftp-wildcard \
   smtp-mail smtp-multi smtp-ssl smtp-tls smtp-vrfy smtp-expn rtsp \
   externalsocket resolve progressfunc pop3-retr pop3-list pop3-uidl pop3-dele \
-  pop3-top pop3-stat pop3-noop pop3-ssl pop3-tls imap-list imap-fetch \
+  pop3-top pop3-stat pop3-noop pop3-ssl pop3-tls pop3-multi imap-list \
-  imap-store imap-append imap-examine imap-search imap-create imap-delete \
+  imap-fetch imap-store imap-append imap-examine imap-search imap-create \
-  imap-copy imap-noop imap-ssl imap-tls url2file sftpget ftpsget postinmemory
+  imap-delete imap-copy imap-noop imap-ssl imap-tls url2file sftpget ftpsget \
+  postinmemory
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

docs/examples/pop3-multi.c

@@ -0,0 +1,143 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2014, 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 http://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.
+ *
+ ***************************************************************************/
+#include <stdio.h>
+#include <curl/curl.h>
+
+/* This is a simple example showing how to retrieve mail using libcurl's POP3
+ * capabilities. It builds on the smtp-mail.c example to demonstrate how to use
+ * libcurl's multi interface.
+ *
+ * Note that this example requires libcurl 7.20.0 or above.
+ */
+
+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 retreive message 1 from the user's mailbox */
+  curl_easy_setopt(curl, CURLOPT_URL, "pop3://pop.example.com/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;
+
+    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 */
+    curl_multi_fdset(mcurl, &fdread, &fdwrite, &fdexcep, &maxfd);
+
+    /* In a real-world program you OF COURSE check the return code of the
+       function calls. On success, the value of maxfd is guaranteed to be
+       greater or equal than -1. We call select(maxfd + 1, ...), specially in
+       case of (maxfd == -1), we call select(0, ...), which is basically equal
+       to sleep. */
+    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;
+}