1 files changed, 15 insertions, 7 deletions
diff --git a/otherlibs/win32unix/socket.c b/otherlibs/win32unix/socket.c
index cdcd34a6d..c543bcf88 100644
--- a/otherlibs/win32unix/socket.c
+++ b/otherlibs/win32unix/socket.c
@@ -24,20 +24,28 @@ int socket_type_table[] = {
   SOCK_STREAM, SOCK_DGRAM, SOCK_RAW, SOCK_SEQPACKET
 };
 
-value unix_socket(domain, type, proto) /* ML */
+value unix_socket(domain, type, proto, synchronous) /* ML */
      value domain, type, proto;
 {
   SOCKET s;
-  int optionValue;
-
-  /* Set sockets to synchronous mode  */
-  optionValue = SO_SYNCHRONOUS_NONALERT;
-  setsockopt(INVALID_SOCKET, SOL_SOCKET, SO_OPENTYPE, 
-             (char *)&optionValue, sizeof(optionValue));
+  int oldvalue, newvalue, retcode;
 
+  retcode = getsockopt(INVALID_SOCKET, SOL_SOCKET, SO_OPENTYPE,
+                       (char *) &oldvalue, sizeof(oldvalue));
+  if (retcode == 0) {
+    /* Set sockets to synchronous or asnychronous mode, as requested */
+    newvalue = Bool_val(synchronous) ? SO_SYNCHRONOUS_NONALERT : 0;
+    setsockopt(INVALID_SOCKET, SOL_SOCKET, SO_OPENTYPE, 
+               (char *) &newvalue, sizeof(newvalue));
+  }
   s = socket(socket_domain_table[Int_val(domain)],
                    socket_type_table[Int_val(type)],
                    Int_val(proto));
+  if (retcode == 0) {
+    /* Restore initial mode */
+    setsockopt(INVALID_SOCKET, SOL_SOCKET, SO_OPENTYPE, 
+               (char *) &oldvalue, sizeof(oldvalue));
+  }
   if (s == INVALID_SOCKET) unix_error(WSAGetLastError(), "socket", Nothing);
   return win_alloc_handle((HANDLE) s);
 }