usr/src/cmd/fm/fmd/common/fmd_list.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 /*
  30  * Embedded Linked Lists
  31  *
  32  * Simple doubly-linked list implementation.  This implementation assumes that
  33  * each list element contains an embedded fmd_list_t (previous and next
  34  * pointers), which is typically the first member of the element struct.
  35  * An additional fmd_list_t is used to store the head (l_next) and tail
  36  * (l_prev) pointers.  The current head and tail list elements have their
  37  * previous and next pointers set to NULL, respectively.
  38  *
  39  * NOTE: The embeddable list code in this file intentionally provides no
  40  * locking of any kind.  The implementation of any list in fmd must provide
  41  * an appropriate locking strategy to protect the list or to protect access
  42  * to the embedded fmd_list_t inside of each list element to avoid corruption.
  43  * Refer to comments in the source files that use fmd_list_t for lock details.
  44  */
  45
  46 #include <fmd_subr.h>
  47 #include <fmd_list.h>
  48
  49 void
  50 fmd_list_append(fmd_list_t *lp, void *new)
  51 {
  52         fmd_list_t *p = lp->l_prev;     /* p = tail list element */
  53         fmd_list_t *q = new;            /* q = new list element */
  54
  55         lp->l_prev = q;
  56         q->l_prev = p;
  57         q->l_next = NULL;
  58
  59         if (p != NULL) {
  60                 ASSERT(p->l_next == NULL);
  61                 p->l_next = q;
  62         } else {
  63                 ASSERT(lp->l_next == NULL);
  64                 lp->l_next = q;
  65         }
  66 }
  67
  68 void
  69 fmd_list_prepend(fmd_list_t *lp, void *new)
  70 {
  71         fmd_list_t *p = new;            /* p = new list element */
  72         fmd_list_t *q = lp->l_next;     /* q = head list element */
  73
  74         lp->l_next = p;
  75         p->l_prev = NULL;
  76         p->l_next = q;
  77
  78         if (q != NULL) {
  79                 ASSERT(q->l_prev == NULL);
  80                 q->l_prev = p;
  81         } else {
  82                 ASSERT(lp->l_prev == NULL);
  83                 lp->l_prev = p;
  84         }
  85 }
  86
  87 void
  88 fmd_list_insert_before(fmd_list_t *lp, void *before_me, void *new)
  89 {
  90         fmd_list_t *p = before_me;
  91         fmd_list_t *q = new;
  92
  93         if (p == NULL || p->l_prev == NULL) {
  94                 fmd_list_prepend(lp, new);
  95                 return;
  96         }
  97
  98         q->l_prev = p->l_prev;
  99         q->l_next = p;
 100         p->l_prev = q;
 101         q->l_prev->l_next = q;
 102 }
 103
 104 void
 105 fmd_list_insert_after(fmd_list_t *lp, void *after_me, void *new)
 106 {
 107         fmd_list_t *p = after_me;
 108         fmd_list_t *q = new;
 109
 110         if (p == NULL || p->l_next == NULL) {
 111                 fmd_list_append(lp, new);
 112                 return;
 113         }
 114
 115         q->l_next = p->l_next;
 116         q->l_prev = p;
 117         p->l_next = q;
 118         q->l_next->l_prev = q;
 119 }
 120
 121 void
 122 fmd_list_delete(fmd_list_t *lp, void *existing)
 123 {
 124         fmd_list_t *p = existing;
 125
 126         if (p->l_prev != NULL)
 127                 p->l_prev->l_next = p->l_next;
 128         else
 129                 lp->l_next = p->l_next;
 130
 131         if (p->l_next != NULL)
 132                 p->l_next->l_prev = p->l_prev;
 133         else
 134                 lp->l_prev = p->l_prev;
 135 }