gistfile1.txt

diff --git a/ext/net/gauche-net.h b/ext/net/gauche-net.h
index 7377a36..07ee38a 100644
--- a/ext/net/gauche-net.h
+++ b/ext/net/gauche-net.h
@@ -196,6 +196,10 @@ extern ScmObj Scm_InetAddressToString(ScmObj addr, int proto);
 typedef struct ScmSocketRec {
     SCM_HEADER;
     Socket fd;                     /* INVALID_SOCKET if closed */
+#ifdef GAUCHE_WINDOWS
+    int crt_fd;                 /* integer fd allocated by open_osfhandle.
+                                   -1 if CRT fd isn't allocated yet. */
+#endif
     int status;
     int type;
     ScmSockAddr *address;
diff --git a/ext/net/net.c b/ext/net/net.c
index 7b4ff02..e8b8b49 100644
--- a/ext/net/net.c
+++ b/ext/net/net.c
@@ -92,6 +92,9 @@ ScmSocket *make_socket(Socket fd, int type)
     ScmSocket *s = SCM_NEW(ScmSocket);
     SCM_SET_CLASS(s, SCM_CLASS_SOCKET);
     s->fd = fd;
+#ifdef GAUCHE_WINDOWS
+    s->crt_fd = -1;
+#endif
     s->status = SCM_SOCKET_STATUS_NONE;
     s->inPort = s->outPort = NULL;
     s->address = NULL;
@@ -174,7 +177,10 @@ ScmObj Scm_SocketInputPort(ScmSocket *sock, int buffering)
 #ifndef GAUCHE_WINDOWS
 	infd = sock->fd;
 #else  /*GAUCHE_WINDOWS*/
-	infd = _open_osfhandle(sock->fd, O_RDONLY);
+        if (sock->crt_fd < 0) {
+            sock->crt_fd = _open_osfhandle(sock->fd, 0);
+        }
+        infd = sock->crt_fd;
 #endif /*GAUCHE_WINDOWS*/
         if (infd == INVALID_SOCKET) sockport_err(sock, "input");
 
@@ -201,7 +207,10 @@ ScmObj Scm_SocketOutputPort(ScmSocket *sock, int buffering)
 #ifndef GAUCHE_WINDOWS
 	outfd = sock->fd;
 #else  /*GAUCHE_WINDOWS*/
-	outfd = _open_osfhandle(sock->fd, 0);
+        if (sock->crt_fd < 0) {
+            sock->crt_fd = _open_osfhandle(sock->fd, 0);
+        }
+	outfd = sock->crt_fd;
 #endif /*GAUCHE_WINDOWS*/
         if (outfd == INVALID_SOCKET) sockport_err(sock, "output");