socket_shutdown improvements

Hello Manuel,

I've seen your recent changes to socket_shutdown.
Maybe you could go one step further and support
a common use case (SHUT_WR) directly?

Attached to this email you can find a little
client/server example application:
1) client writes characters, server reads them
2) client shuts down connection for writing
3) server reads eof-object,
   writes response (here: received byte count),
   performs socket shutdown and close
4) client reads response until eof-object,
   prints response and closes socket

The attached ./make-and-test.bash should print:
Response string = '11'
(This is the byte count of "hello world".)

From my exposure to other languages (mozart/oz),
shutdown and close are two separate issues, and
can be implemented independently of each other.
While low-level close() for all practical purposes
implies a shutdown, the partial shutdown() for one 
direction does have its use.

In essence, I guess that the close_socket arg
can be removed from socket_shutdown entirely;
at least it is unclear to me why the call to
shutdown() depends on it.

Maybe you can think of a better way to expose the
three shutdown variants (SHUT_RD, SHUT_WR, SHUT_RDWR)?

Cheers & thanks a lot for bigloo development,

Andreas

============== Diff Summary ============
--- csocket.c
+++ csocket_extra.c
@@ ... @@
 
+#if( !defined( SHUT_RD ) )
+#  define SHUT_RD 0
+#endif
+#if( !defined( SHUT_WR ) )
+#  define SHUT_WR 1
+#endif
 #if( !defined( SHUT_RDWR ) )
 #  define SHUT_RDWR 2
 #endif
   
@@ ... @@
 /*---------------------------------------------------------------------*/
 /*    imports ...                                                      */
 /*---------------------------------------------------------------------*/
 extern obj_t bgl_close_input_port( obj_t );
+extern obj_t bgl_close_output_port( obj_t );
 
@@ ... @@
 
 /*---------------------------------------------------------------------*/
 /*    obj_t                                                            */
-/*    socket_shutdown ...                                              */
+/*    socket_shutdown and friends (.._read, .._write, .._read_write)   */
 /*---------------------------------------------------------------------*/

 BGL_RUNTIME_DEF obj_t
-socket_shutdown( obj_t sock, int close_socket ) {
+socket_shutdown( obj_t sock, int how ) {
    int fd = SOCKET( sock ).fd;
 
    if( fd > 0 ) {
-      if( close_socket ) {
-	 if( shutdown( fd, SHUT_RDWR ) ) {
+        if( shutdown( fd, how ) ) {
 	    char *buffer = alloca( 1024 );
-
-	    /* force closing the socket anyhow */
-	    socket_close( sock );
-	    
 	    BGL_MUTEX_LOCK( socket_mutex );
-	    sprintf( buffer, "cannot shutdown socket, %s %d", strerror( errno ), fd );
+           sprintf( buffer, "cannot shutdown socket (how = %d), %s %d",
+                    how, strerror( errno ), fd );
 	    BGL_MUTEX_UNLOCK( socket_mutex );
 	    socket_error( "socket-shutdown", buffer, sock );
 	 }
       }
-      socket_close( sock );
+    
+    if( ( how == SHUT_RD ) || ( how == SHUT_RDWR ) ) {
+        if( INPUT_PORTP( SOCKET( sock ).input ) ) {
+	    bgl_close_input_port( SOCKET( sock ).input );
+	}
+    }
+
+    if( ( how == SHUT_WR ) || ( how == SHUT_RDWR ) ) {
+        if( OUTPUT_PORTP( SOCKET( sock ).output ) ) {
+	    bgl_close_output_port( SOCKET( sock ).output );
+	}
    }
    
    return BUNSPEC;
 }
+
+BGL_RUNTIME_DEF obj_t
+socket_shutdown_read( obj_t sock ) {
+    return socket_shutdown( sock, SHUT_RD );
+}
+BGL_RUNTIME_DEF obj_t
+socket_shutdown_write( obj_t sock ) {
+    return socket_shutdown( sock , SHUT_WR );
+}
+BGL_RUNTIME_DEF obj_t
+socket_shutdown_read_write( obj_t sock ) {
+    return socket_shutdown( sock, SHUT_RDWR );
+}