[glib/glib-2-54] Revert "GSocket: Fix race conditions on Win32 if multiple threads are waiting on conditions for the

[Ignacio Casal Quinteiro <icq src gnome org>]

commit f9d95de490847808bcdea2096840e30bb97bbfa1
Author: Ignacio Casal Quinteiro <qignacio amazon com>
Date:   Thu May 11 17:51:56 2017 +0200

    Revert "GSocket: Fix race conditions on Win32 if multiple threads are waiting on conditions for the same 
socket"
    
    This reverts commit 799f8dcd46fb40ea206d9f1b5468db62cc00a72e.
    This patch seems to break applications that use GTask specific
    operations with GSocket. We will need to investigate a bit more
    on this issue but for now we revert it and leave it for the
    next major release.

 gio/gsocket.c |   94 ++++++++++++++++-----------------------------------------
 1 files changed, 26 insertions(+), 68 deletions(-)
---
diff --git a/gio/gsocket.c b/gio/gsocket.c
index eea502c..ba90be5 100644
--- a/gio/gsocket.c
+++ b/gio/gsocket.c
@@ -252,14 +252,11 @@ struct _GSocketPrivate
   guint           connect_pending : 1;
 #ifdef G_OS_WIN32
   WSAEVENT        event;
-  gboolean        waiting;
-  DWORD           waiting_result;
   int             current_events;
   int             current_errors;
   int             selected_events;
   GList          *requested_conditions; /* list of requested GIOCondition * */
   GMutex          win32_source_lock;
-  GCond           win32_source_cond;
 #endif
 
   struct {
@@ -346,10 +343,8 @@ socket_strerror (int err)
 static void
 _win32_unset_event_mask (GSocket *socket, int mask)
 {
-  g_mutex_lock (&socket->priv->win32_source_lock);
   socket->priv->current_events &= ~mask;
   socket->priv->current_errors &= ~mask;
-  g_mutex_unlock (&socket->priv->win32_source_lock);
 }
 #else
 #define win32_unset_event_mask(_socket, _mask)
@@ -847,7 +842,6 @@ g_socket_finalize (GObject *object)
 
   g_assert (socket->priv->requested_conditions == NULL);
   g_mutex_clear (&socket->priv->win32_source_lock);
-  g_cond_clear (&socket->priv->win32_source_cond);
 #endif
 
   for (i = 0; i < RECV_ADDR_CACHE_SIZE; i++)
@@ -1075,7 +1069,6 @@ g_socket_init (GSocket *socket)
 #ifdef G_OS_WIN32
   socket->priv->event = WSA_INVALID_EVENT;
   g_mutex_init (&socket->priv->win32_source_lock);
-  g_cond_init (&socket->priv->win32_source_cond);
 #endif
 }
 
@@ -2459,8 +2452,6 @@ g_socket_accept (GSocket       *socket,
 
   while (TRUE)
     {
-      win32_unset_event_mask (socket, FD_ACCEPT);
-
       if ((ret = accept (socket->priv->fd, NULL, 0)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2475,6 +2466,8 @@ g_socket_accept (GSocket       *socket,
               errsv == EAGAIN)
 #endif
             {
+              win32_unset_event_mask (socket, FD_ACCEPT);
+
               if (socket->priv->blocking)
                 {
                   if (!g_socket_condition_wait (socket,
@@ -2491,6 +2484,8 @@ g_socket_accept (GSocket       *socket,
       break;
     }
 
+  win32_unset_event_mask (socket, FD_ACCEPT);
+
 #ifdef G_OS_WIN32
   {
     /* The socket inherits the accepting sockets event mask and even object,
@@ -2579,8 +2574,6 @@ g_socket_connect (GSocket         *socket,
 
   while (1)
     {
-      win32_unset_event_mask (socket, FD_CONNECT);
-
       if (connect (socket->priv->fd, (struct sockaddr *) &buffer,
                   g_socket_address_get_native_size (address)) < 0)
        {
@@ -2595,6 +2588,8 @@ g_socket_connect (GSocket         *socket,
          if (errsv == WSAEWOULDBLOCK)
 #endif
            {
+              win32_unset_event_mask (socket, FD_CONNECT);
+
              if (socket->priv->blocking)
                {
                  if (g_socket_condition_wait (socket, G_IO_OUT, cancellable, error))
@@ -2620,6 +2615,8 @@ g_socket_connect (GSocket         *socket,
       break;
     }
 
+  win32_unset_event_mask (socket, FD_CONNECT);
+
   socket->priv->connected_read = TRUE;
   socket->priv->connected_write = TRUE;
 
@@ -2799,8 +2796,6 @@ g_socket_receive_with_timeout (GSocket       *socket,
 
   while (1)
     {
-      win32_unset_event_mask (socket, FD_READ);
-
       if ((ret = recv (socket->priv->fd, buffer, size, 0)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2815,6 +2810,8 @@ g_socket_receive_with_timeout (GSocket       *socket,
               errsv == EAGAIN)
 #endif
             {
+              win32_unset_event_mask (socket, FD_READ);
+
               if (timeout != 0)
                 {
                   if (!block_on_timeout (socket, G_IO_IN, timeout, start_time,
@@ -2825,10 +2822,14 @@ g_socket_receive_with_timeout (GSocket       *socket,
                 }
             }
 
+         win32_unset_event_mask (socket, FD_READ);
+
          socket_set_error_lazy (error, errsv, _("Error receiving data: %s"));
          return -1;
        }
 
+      win32_unset_event_mask (socket, FD_READ);
+
       break;
     }
 
@@ -2994,8 +2995,6 @@ g_socket_send_with_timeout (GSocket       *socket,
 
   while (1)
     {
-      win32_unset_event_mask (socket, FD_WRITE);
-
       if ((ret = send (socket->priv->fd, buffer, size, G_SOCKET_DEFAULT_SEND_FLAGS)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -3010,6 +3009,8 @@ g_socket_send_with_timeout (GSocket       *socket,
               errsv == EAGAIN)
 #endif
             {
+              win32_unset_event_mask (socket, FD_WRITE);
+
               if (timeout != 0)
                 {
                   if (!block_on_timeout (socket, G_IO_OUT, timeout, start_time,
@@ -3424,7 +3425,7 @@ remove_condition_watch (GSocket      *socket,
 }
 
 static GIOCondition
-update_condition_unlocked (GSocket *socket)
+update_condition (GSocket *socket)
 {
   WSANETWORKEVENTS events;
   GIOCondition condition;
@@ -3491,16 +3492,6 @@ update_condition_unlocked (GSocket *socket)
 
   return condition;
 }
-
-static GIOCondition
-update_condition (GSocket *socket)
-{
-  GIOCondition res;
-  g_mutex_lock (&socket->priv->win32_source_lock);
-  res = update_condition_unlocked (socket);
-  g_mutex_unlock (&socket->priv->win32_source_lock);
-  return res;
-}
 #endif
 
 typedef struct {
@@ -3896,44 +3887,11 @@ g_socket_condition_timed_wait (GSocket       *socket,
     if (timeout == -1)
       timeout = WSA_INFINITE;
 
-    g_mutex_lock (&socket->priv->win32_source_lock);
-    current_condition = update_condition_unlocked (socket);
+    current_condition = update_condition (socket);
     while ((condition & current_condition) == 0)
       {
-        if (!socket->priv->waiting)
-          {
-            socket->priv->waiting = TRUE;
-            socket->priv->waiting_result = 0;
-            g_mutex_unlock (&socket->priv->win32_source_lock);
-
-            res = WSAWaitForMultipleEvents (num_events, events, FALSE, timeout, FALSE);
-
-            g_mutex_lock (&socket->priv->win32_source_lock);
-            socket->priv->waiting = FALSE;
-            socket->priv->waiting_result = res;
-            g_cond_broadcast (&socket->priv->win32_source_cond);
-          }
-        else
-          {
-            if (timeout != WSA_INFINITE)
-              {
-                if (!g_cond_wait_until (&socket->priv->win32_source_cond, &socket->priv->win32_source_lock, 
timeout))
-                  {
-                    res = WSA_WAIT_TIMEOUT;
-                    break;
-                  }
-                else
-                  {
-                    res = socket->priv->waiting_result;
-                  }
-              }
-            else
-              {
-                g_cond_wait (&socket->priv->win32_source_cond, &socket->priv->win32_source_lock);
-                res = socket->priv->waiting_result;
-              }
-          }
-
+       res = WSAWaitForMultipleEvents (num_events, events,
+                                       FALSE, timeout, FALSE);
        if (res == WSA_WAIT_FAILED)
          {
            int errsv = get_socket_errno ();
@@ -3954,7 +3912,7 @@ g_socket_condition_timed_wait (GSocket       *socket,
        if (g_cancellable_set_error_if_cancelled (cancellable, error))
          break;
 
-        current_condition = update_condition_unlocked (socket);
+       current_condition = update_condition (socket);
 
        if (timeout != WSA_INFINITE)
          {
@@ -3963,7 +3921,6 @@ g_socket_condition_timed_wait (GSocket       *socket,
              timeout = 0;
          }
       }
-    g_mutex_unlock (&socket->priv->win32_source_lock);
     remove_condition_watch (socket, &condition);
     if (num_events > 1)
       g_cancellable_release_fd (cancellable);
@@ -4461,8 +4418,6 @@ g_socket_send_message_with_timeout (GSocket                *socket,
 
     while (1)
       {
-        win32_unset_event_mask (socket, FD_WRITE);
-
        if (address)
          result = WSASendTo (socket->priv->fd,
                              bufs, num_vectors,
@@ -4484,6 +4439,8 @@ g_socket_send_message_with_timeout (GSocket                *socket,
 
            if (errsv == WSAEWOULDBLOCK)
               {
+                win32_unset_event_mask (socket, FD_WRITE);
+
                 if (timeout != 0)
                   {
                     if (!block_on_timeout (socket, G_IO_OUT, timeout,
@@ -4931,8 +4888,6 @@ g_socket_receive_message_with_timeout (GSocket                 *socket,
     /* do it */
     while (1)
       {
-        win32_unset_event_mask (socket, FD_READ);
-
        addrlen = sizeof addr;
        if (address)
          result = WSARecvFrom (socket->priv->fd,
@@ -4954,6 +4909,8 @@ g_socket_receive_message_with_timeout (GSocket                 *socket,
 
             if (errsv == WSAEWOULDBLOCK)
               {
+                win32_unset_event_mask (socket, FD_READ);
+
                 if (timeout != 0)
                   {
                     if (!block_on_timeout (socket, G_IO_IN, timeout,
@@ -4967,6 +4924,7 @@ g_socket_receive_message_with_timeout (GSocket                 *socket,
            socket_set_error_lazy (error, errsv, _("Error receiving message: %s"));
            return -1;
          }
+       win32_unset_event_mask (socket, FD_READ);
        break;
       }