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Diffstat (limited to 'libc/inet/rpc/pmap_prot2.c')
| -rw-r--r-- | libc/inet/rpc/pmap_prot2.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/libc/inet/rpc/pmap_prot2.c b/libc/inet/rpc/pmap_prot2.c new file mode 100644 index 000000000..e2a8214d4 --- /dev/null +++ b/libc/inet/rpc/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); + } +} |