gsocket: always try before waiting for condition

When implementing blocking operations on top of
nonblocking sockets we should always first try to
perform the operation and then if needed handle
EAGAIN and wait with g_socket_wait_condition.
This is an optimization since we avoid calling
wait condition when it is not needed, but most
importantly this fixes hangs on win32 where some
events (in particular FD_WRITE) are only emitted
after the operation fails with EWOULDBLOCK.

https://bugzilla.gnome.org/show_bug.cgi?id=732439
https://bugzilla.gnome.org/show_bug.cgi?id=741707

diff --git a/gio/gsocket.c b/gio/gsocket.c
index d9e135d..f144674 100644 (file)
--- a/gio/gsocket.c
+++ b/gio/gsocket.c
@@ -2230,31 +2230,31 @@ g_socket_accept (GSocket       *socket,
 
   while (TRUE)
     {
-      if (socket->priv->blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_IN, cancellable, error))
-       return NULL;
-
       if ((ret = accept (socket->priv->fd, NULL, 0)) < 0)
        {
          int errsv = get_socket_errno ();
 
-         win32_unset_event_mask (socket, FD_ACCEPT);
-
          if (errsv == EINTR)
            continue;
 
-         if (socket->priv->blocking)
-           {
 #ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_ACCEPT);
+
+              if (socket->priv->blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_IN, cancellable, error))
+                    return NULL;
+
+                  continue;
+                }
+            }
 
          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
@@ -2368,6 +2368,8 @@ 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))
@@ -2602,11 +2604,6 @@ g_socket_receive_with_blocking (GSocket       *socket,
 
   while (1)
     {
-      if (blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_IN, cancellable, error))
-       return -1;
-
       if ((ret = recv (socket->priv->fd, buffer, size, 0)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2614,17 +2611,24 @@ g_socket_receive_with_blocking (GSocket       *socket,
          if (errsv == EINTR)
            continue;
 
-         if (blocking)
-           {
 #ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_READ);
+
+              if (blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_IN, cancellable, error))
+                    return -1;
+
+                  continue;
+                }
+            }
 
          win32_unset_event_mask (socket, FD_READ);
 
@@ -2777,11 +2781,6 @@ g_socket_send_with_blocking (GSocket       *socket,
 
   while (1)
     {
-      if (blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_OUT, cancellable, error))
-       return -1;
-
       if ((ret = send (socket->priv->fd, buffer, size, G_SOCKET_DEFAULT_SEND_FLAGS)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2790,21 +2789,23 @@ g_socket_send_with_blocking (GSocket       *socket,
            continue;
 
 #ifdef WSAEWOULDBLOCK
-         if (errsv == WSAEWOULDBLOCK)
-           win32_unset_event_mask (socket, FD_WRITE);
-#endif
-
-         if (blocking)
-           {
-#ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_WRITE);
+
+              if (blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_OUT, cancellable, error))
+                    return -1;
+
+                  continue;
+                }
+            }
 
          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
@@ -3874,11 +3875,6 @@ g_socket_send_message (GSocket                *socket,
 
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_OUT, cancellable, error))
-         return -1;
-
        result = sendmsg (socket->priv->fd, &msg, flags | G_SOCKET_DEFAULT_SEND_FLAGS);
        if (result < 0)
          {
@@ -3890,7 +3886,13 @@ g_socket_send_message (GSocket                *socket,
            if (socket->priv->blocking &&
                (errsv == EWOULDBLOCK ||
                 errsv == EAGAIN))
-             continue;
+              {
+                if (!g_socket_condition_wait (socket,
+                                              G_IO_OUT, cancellable, error))
+                  return -1;
+
+                continue;
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
@@ -3942,11 +3944,6 @@ g_socket_send_message (GSocket                *socket,
 
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_OUT, cancellable, error))
-         return -1;
-
        if (address)
          result = WSASendTo (socket->priv->fd,
                              bufs, num_vectors,
@@ -3967,11 +3964,18 @@ g_socket_send_message (GSocket                *socket,
              continue;
 
            if (errsv == WSAEWOULDBLOCK)
-             win32_unset_event_mask (socket, FD_WRITE);
+              {
+                win32_unset_event_mask (socket, FD_WRITE);
 
-           if (socket->priv->blocking &&
-               errsv == WSAEWOULDBLOCK)
-             continue;
+                if (socket->priv->blocking)
+                  {
+                    if (!g_socket_condition_wait (socket,
+                                                  G_IO_OUT, cancellable, error))
+                      return -1;
+
+                    continue;
+                  }
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
@@ -4634,11 +4638,6 @@ g_socket_receive_message (GSocket                 *socket,
     /* do it */
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_IN, cancellable, error))
-         return -1;
-
        addrlen = sizeof addr;
        if (address)
          result = WSARecvFrom (socket->priv->fd,
@@ -4658,11 +4657,19 @@ g_socket_receive_message (GSocket                 *socket,
            if (errsv == WSAEINTR)
              continue;
 
-           win32_unset_event_mask (socket, FD_READ);
+            if (errsv == WSAEWOULDBLOCK)
+              {
+                win32_unset_event_mask (socket, FD_READ);
 
-           if (socket->priv->blocking &&
-               errsv == WSAEWOULDBLOCK)
-             continue;
+                if (socket->priv->blocking)
+                  {
+                    if (!g_socket_condition_wait (socket,
+                                                  G_IO_IN, cancellable, error))
+                      return -1;
+
+                    continue;
+                  }
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),