From 1f8962d23d3a2e5f23d64ea931bc0dc4c0e335fd Mon Sep 17 00:00:00 2001
From: =?utf8?q?R=C3=A9mi=20Denis-Courmont?= <rdenis@simphalempin.com>
Date: Sun, 18 Jan 2009 16:40:50 +0200
Subject: [PATCH] Revert "Improve Win32 poll replacement (and fix #1949)" et al

Looks like Winsock events operate in a weird and barely adaptable way.
Fixes #2369.

This reverts commit c6ea17a3ce7e5884c323a66bd48f09f551dbb86d.
This reverts commit 1a582db112f0d898f93bdcc618e06d75ff8f2410.
This reverts commit 8bda7d7287446b0f5b54fe69c07d600cb0bbd1a2.
This reverts commit acade544006e80a73facb152fa53437e21a99a2f.
---
 src/network/poll.c | 111 +++++++++++++++++++++------------------------
 1 file changed, 52 insertions(+), 59 deletions(-)

diff --git a/src/network/poll.c b/src/network/poll.c
index 5590b36a21..f6f9050eff 100644
--- a/src/network/poll.c
+++ b/src/network/poll.c
@@ -1,7 +1,7 @@
 /*****************************************************************************
  * poll.c: I/O event multiplexing
  *****************************************************************************
- * Copyright © 2007-2008 Rémi Denis-Courmont
+ * Copyright © 2007 Rémi Denis-Courmont
  * $Id$
  *
  * Author: Rémi Denis-Courmont
@@ -28,7 +28,7 @@
 #include <vlc_common.h>
 #include <vlc_network.h>
 
-#ifndef WIN32
+#ifdef HAVE_POLL
 struct pollfd;
 
 int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
@@ -36,80 +36,73 @@ int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
     (void)fds; (void)nfds; (void)timeout;
     abort ();
 }
-#else
+#else /* !HAVE_POLL */
 #include <string.h>
 #include <stdlib.h>
 #include <vlc_network.h>
 
 int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
 {
-    WSAEVENT phEvents[nfds];
-    DWORD val;
-
-    vlc_testcancel ();
+    fd_set rdset, wrset, exset;
+    struct timeval tv = { 0, 0 };
+    int val = -1;
 
+    FD_ZERO (&rdset);
+    FD_ZERO (&wrset);
+    FD_ZERO (&exset);
     for (unsigned i = 0; i < nfds; i++)
     {
-        long events = FD_CLOSE;
+        int fd = fds[i].fd;
+        if (val < fd)
+            val = fd;
 
+        /* With POSIX, FD_SET & FD_ISSET are not defined if fd is negative or
+	 * bigger or equal than FD_SETSIZE. That is one of the reasons why VLC
+	 * uses poll() rather than select(). Most POSIX systems implement
+	 * fd_set has a bit field with no sanity checks. This is especially bad
+	 * on systems (such as BSD) that have no process open files limit by
+	 * default, such that it is quite feasible to get fd >= FD_SETSIZE.
+	 * The next instructions will result in a buffer overflow if run on
+	 * a POSIX system, and the later FD_ISSET will do undefined memory
+	 * access.
+	 *
+	 * With Winsock, fd_set is a table of integers. This is awfully slow.
+	 * However, FD_SET and FD_ISSET silently and safely discard
+	 * overflows. If it happens we will loose socket events. Note that
+	 * most (if not all) Winsock SOCKET handles are actually bigger than
+	 * FD_SETSIZE in terms of absolute value - they are not POSIX file
+	 * descriptors. From Vista, there is a much nicer WSAPoll(), but Mingw
+	 * is yet to support it.
+	 *
+	 * With BeOS, the situation is unknown (FIXME: document).
+	 */
         if (fds[i].events & POLLIN)
-            events |= FD_READ | FD_ACCEPT;
+            FD_SET (fd, &rdset);
         if (fds[i].events & POLLOUT)
-            events |= FD_WRITE;
+            FD_SET (fd, &wrset);
         if (fds[i].events & POLLPRI)
-            events |= FD_OOB;
-        fds[i].revents = 0;
-
-        phEvents[i] = WSACreateEvent ();
-        WSAEventSelect (fds[i].fd, phEvents[i], events);
+            FD_SET (fd, &exset);
     }
 
-    int ret = 0, n = 0;
-
-    switch (WaitForMultipleObjectsEx (nfds, phEvents, FALSE, timeout, TRUE))
+    if (timeout >= 0)
     {
-      case WAIT_IO_COMPLETION:
-        WSASetLastError (WSAEINTR);
-        ret = -1;
-        break;
-      case WAIT_TIMEOUT:
-        ret = 0;
-        break;
-      default:
-        for (unsigned i = 0; i < nfds; i++)
-        {
-            WSANETWORKEVENTS events;
-            if (WSAEnumNetworkEvents (fds[i].fd, phEvents[i], &events))
-            {
-                fds[i].revents |= POLLNVAL;
-                ret = -1;
-                continue;
-            }
-            if (events.lNetworkEvents & FD_CLOSE)
-               fds[i].revents |= POLLHUP | (fds[i].events & POLLIN);
-            if (events.lNetworkEvents & FD_ACCEPT)
-               fds[i].revents |= POLLIN;
-            if (events.lNetworkEvents & FD_OOB)
-               fds[i].revents |= POLLPRI;
-            if (events.lNetworkEvents & FD_READ)
-               fds[i].revents |= POLLIN;
-            if (events.lNetworkEvents & FD_WRITE)
-            {
-                fds[i].revents |= POLLOUT;
-                if (events.iErrorCode[FD_WRITE_BIT])
-                    fds[i].revents |= POLLERR;
-            }
-            if (fds[i].revents)
-                n++;
-        }
-        if (ret == 0)
-            ret = n;
+        div_t d = div (timeout, 1000);
+        tv.tv_sec = d.quot;
+        tv.tv_usec = d.rem * 1000;
     }
 
-    for (unsigned i = 0; i < nfds; i++)
-        WSACloseEvent (phEvents[i]);
-    vlc_testcancel ();
+    val = select (val + 1, &rdset, &wrset, &exset,
+                  (timeout >= 0) ? &tv : NULL);
+    if (val == -1)
+        return -1;
 
-    return ret;
+    for (unsigned i = 0; i < nfds; i++)
+    {
+        int fd = fds[i].fd;
+        fds[i].revents = (FD_ISSET (fd, &rdset) ? POLLIN : 0)
+                       | (FD_ISSET (fd, &wrset) ? POLLOUT : 0)
+                       | (FD_ISSET (fd, &exset) ? POLLPRI : 0);
+    }
+    return val;
 }
-#endif /* WIN32 */
+#endif /* !HAVE_POLL */
-- 
2.39.5