pmap_prot2.c 3.7 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116
  1. /* @(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC */
  2. /*
  3. * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
  4. * unrestricted use provided that this legend is included on all tape
  5. * media and as a part of the software program in whole or part. Users
  6. * may copy or modify Sun RPC without charge, but are not authorized
  7. * to license or distribute it to anyone else except as part of a product or
  8. * program developed by the user.
  9. *
  10. * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  11. * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  12. * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  13. *
  14. * Sun RPC is provided with no support and without any obligation on the
  15. * part of Sun Microsystems, Inc. to assist in its use, correction,
  16. * modification or enhancement.
  17. *
  18. * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  19. * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  20. * OR ANY PART THEREOF.
  21. *
  22. * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  23. * or profits or other special, indirect and consequential damages, even if
  24. * Sun has been advised of the possibility of such damages.
  25. *
  26. * Sun Microsystems, Inc.
  27. * 2550 Garcia Avenue
  28. * Mountain View, California 94043
  29. */
  30. #define __FORCE_GLIBC__
  31. #include <features.h>
  32. /*
  33. * pmap_prot2.c
  34. * Protocol for the local binder service, or pmap.
  35. *
  36. * Copyright (C) 1984, Sun Microsystems, Inc.
  37. */
  38. #include <rpc/types.h>
  39. #include <rpc/xdr.h>
  40. #include <rpc/pmap_prot.h>
  41. /*
  42. * What is going on with linked lists? (!)
  43. * First recall the link list declaration from pmap_prot.h:
  44. *
  45. * struct pmaplist {
  46. * struct pmap pml_map;
  47. * struct pmaplist *pml_map;
  48. * };
  49. *
  50. * Compare that declaration with a corresponding xdr declaration that
  51. * is (a) pointer-less, and (b) recursive:
  52. *
  53. * typedef union switch (bool_t) {
  54. *
  55. * case TRUE: struct {
  56. * struct pmap;
  57. * pmaplist_t foo;
  58. * };
  59. *
  60. * case FALSE: struct {};
  61. * } pmaplist_t;
  62. *
  63. * Notice that the xdr declaration has no nxt pointer while
  64. * the C declaration has no bool_t variable. The bool_t can be
  65. * interpreted as ``more data follows me''; if FALSE then nothing
  66. * follows this bool_t; if TRUE then the bool_t is followed by
  67. * an actual struct pmap, and then (recursively) by the
  68. * xdr union, pamplist_t.
  69. *
  70. * This could be implemented via the xdr_union primitive, though this
  71. * would cause a one recursive call per element in the list. Rather than do
  72. * that we can ``unwind'' the recursion
  73. * into a while loop and do the union arms in-place.
  74. *
  75. * The head of the list is what the C programmer wishes to past around
  76. * the net, yet is the data that the pointer points to which is interesting;
  77. * this sounds like a job for xdr_reference!
  78. */
  79. bool_t xdr_pmaplist(xdrs, rp)
  80. register XDR *xdrs;
  81. register struct pmaplist **rp;
  82. {
  83. /*
  84. * more_elements is pre-computed in case the direction is
  85. * XDR_ENCODE or XDR_FREE. more_elements is overwritten by
  86. * xdr_bool when the direction is XDR_DECODE.
  87. */
  88. bool_t more_elements;
  89. register int freeing = (xdrs->x_op == XDR_FREE);
  90. register struct pmaplist **next;
  91. #warning expect "next" might be unitialized
  92. while (TRUE) {
  93. more_elements = (bool_t) (*rp != NULL);
  94. if (!xdr_bool(xdrs, &more_elements))
  95. return (FALSE);
  96. if (!more_elements)
  97. return (TRUE); /* we are done */
  98. /*
  99. * the unfortunate side effect of non-recursion is that in
  100. * the case of freeing we must remember the next object
  101. * before we free the current object ...
  102. */
  103. if (freeing)
  104. next = &((*rp)->pml_next);
  105. if (!xdr_reference(xdrs, (caddr_t *) rp,
  106. (u_int) sizeof(struct pmaplist), (xdrproc_t) xdr_pmap))
  107. return (FALSE);
  108. rp = (freeing) ? next : &((*rp)->pml_next);
  109. }
  110. }