initial import

sunrpc/pmap_prot2.c

@@ -0,0 +1,116 @@
+/* @(#)pmap_prot2.c	2.1 88/07/29 4.0 RPCSRC */
+/*
+ * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
+ * unrestricted use provided that this legend is included on all tape
+ * media and as a part of the software program in whole or part.  Users
+ * may copy or modify Sun RPC without charge, but are not authorized
+ * to license or distribute it to anyone else except as part of a product or
+ * program developed by the user.
+ * 
+ * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
+ * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
+ * 
+ * Sun RPC is provided with no support and without any obligation on the
+ * part of Sun Microsystems, Inc. to assist in its use, correction,
+ * modification or enhancement.
+ * 
+ * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
+ * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
+ * OR ANY PART THEREOF.
+ * 
+ * In no event will Sun Microsystems, Inc. be liable for any lost revenue
+ * or profits or other special, indirect and consequential damages, even if
+ * Sun has been advised of the possibility of such damages.
+ * 
+ * Sun Microsystems, Inc.
+ * 2550 Garcia Avenue
+ * Mountain View, California  94043
+ */
+#if !defined(lint) && defined(SCCSIDS)
+static char sccsid[] = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
+#endif
+
+/*
+ * pmap_prot2.c
+ * Protocol for the local binder service, or pmap.
+ *
+ * Copyright (C) 1984, Sun Microsystems, Inc.
+ */
+
+#include <rpc/types.h>
+#include <rpc/xdr.h>
+#include <rpc/pmap_prot.h>
+
+
+/* 
+ * What is going on with linked lists? (!)
+ * First recall the link list declaration from pmap_prot.h:
+ *
+ * struct pmaplist {
+ *	struct pmap pml_map;
+ *	struct pmaplist *pml_map;
+ * };
+ *
+ * Compare that declaration with a corresponding xdr declaration that 
+ * is (a) pointer-less, and (b) recursive:
+ *
+ * typedef union switch (bool_t) {
+ * 
+ *	case TRUE: struct {
+ *		struct pmap;
+ * 		pmaplist_t foo;
+ *	};
+ *
+ *	case FALSE: struct {};
+ * } pmaplist_t;
+ *
+ * Notice that the xdr declaration has no nxt pointer while
+ * the C declaration has no bool_t variable.  The bool_t can be
+ * interpreted as ``more data follows me''; if FALSE then nothing
+ * follows this bool_t; if TRUE then the bool_t is followed by
+ * an actual struct pmap, and then (recursively) by the 
+ * xdr union, pamplist_t.  
+ *
+ * This could be implemented via the xdr_union primitive, though this
+ * would cause a one recursive call per element in the list.  Rather than do
+ * that we can ``unwind'' the recursion
+ * into a while loop and do the union arms in-place.
+ *
+ * The head of the list is what the C programmer wishes to past around
+ * the net, yet is the data that the pointer points to which is interesting;
+ * this sounds like a job for xdr_reference!
+ */
+bool_t
+xdr_pmaplist(xdrs, rp)
+	register XDR *xdrs;
+	register struct pmaplist **rp;
+{
+	/*
+	 * more_elements is pre-computed in case the direction is
+	 * XDR_ENCODE or XDR_FREE.  more_elements is overwritten by
+	 * xdr_bool when the direction is XDR_DECODE.
+	 */
+	bool_t more_elements;
+	register int freeing = (xdrs->x_op == XDR_FREE);
+	register struct pmaplist **next;
+
+	while (TRUE) {
+		more_elements = (bool_t)(*rp != NULL);
+		if (! xdr_bool(xdrs, &more_elements))
+			return (FALSE);
+		if (! more_elements)
+			return (TRUE);  /* we are done */
+		/*
+		 * the unfortunate side effect of non-recursion is that in
+		 * the case of freeing we must remember the next object
+		 * before we free the current object ...
+		 */
+		if (freeing)
+			next = &((*rp)->pml_next); 
+		if (! xdr_reference(xdrs, (caddr_t *)rp,
+		    (u_int)sizeof(struct pmaplist), xdr_pmap))
+			return (FALSE);
+		rp = (freeing) ? next : &((*rp)->pml_next);
+	}
+}