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diff --git a/mDNSResponder/mDNSShared/GenLinkedList.c b/mDNSResponder/mDNSShared/GenLinkedList.c
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+/* -*- Mode: C; tab-width: 4 -*-
+ *
+ * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+
+ File: GenLinkedList.c
+
+ Contains: implementation of generic linked lists.
+
+ Version: 1.0
+ Tabs: 4 spaces
+ */
+
+#include "GenLinkedList.h"
+
+
+// Return the link pointer contained within element e at offset o.
+#define GETLINK( e, o) ( *(void**)((char*) (e) + (o)) )
+
+// Assign the link pointer l to element e at offset o.
+#define ASSIGNLINK( e, l, o) ( *((void**)((char*) (e) + (o))) = (l))
+
+
+// GenLinkedList /////////////////////////////////////////////////////////////
+
+void InitLinkedList( GenLinkedList *pList, size_t linkOffset)
+/* Initialize the block of memory pointed to by pList as a linked list. */
+{
+ pList->Head = NULL;
+ pList->Tail = NULL;
+ pList->LinkOffset = linkOffset;
+}
+
+
+void AddToTail( GenLinkedList *pList, void *elem)
+/* Add a linked list element to the tail of the list. */
+{
+ if ( pList->Tail) {
+ ASSIGNLINK( pList->Tail, elem, pList->LinkOffset);
+ } else
+ pList->Head = elem;
+ ASSIGNLINK( elem, NULL, pList->LinkOffset);
+
+ pList->Tail = elem;
+}
+
+
+void AddToHead( GenLinkedList *pList, void *elem)
+/* Add a linked list element to the head of the list. */
+{
+ ASSIGNLINK( elem, pList->Head, pList->LinkOffset);
+ if ( pList->Tail == NULL)
+ pList->Tail = elem;
+
+ pList->Head = elem;
+}
+
+
+int RemoveFromList( GenLinkedList *pList, void *elem)
+/* Remove a linked list element from the list. Return 0 if it was not found. */
+/* If the element is removed, its link will be set to NULL. */
+{
+ void *iElem, *lastElem;
+
+ for ( iElem = pList->Head, lastElem = NULL; iElem; iElem = GETLINK( iElem, pList->LinkOffset)) {
+ if ( iElem == elem) {
+ if ( lastElem) { // somewhere past the head
+ ASSIGNLINK( lastElem, GETLINK( elem, pList->LinkOffset), pList->LinkOffset);
+ } else { // at the head
+ pList->Head = GETLINK( elem, pList->LinkOffset);
+ }
+ if ( pList->Tail == elem)
+ pList->Tail = lastElem ? lastElem : NULL;
+ ASSIGNLINK( elem, NULL, pList->LinkOffset); // maybe catch a stale reference bug.
+ return 1;
+ }
+ lastElem = iElem;
+ }
+
+ return 0;
+}
+
+
+int ReplaceElem( GenLinkedList *pList, void *elemInList, void *newElem)
+/* Replace an element in the list with a new element, in the same position. */
+{
+ void *iElem, *lastElem;
+
+ if ( elemInList == NULL || newElem == NULL)
+ return 0;
+
+ for ( iElem = pList->Head, lastElem = NULL; iElem; iElem = GETLINK( iElem, pList->LinkOffset))
+ {
+ if ( iElem == elemInList)
+ {
+ ASSIGNLINK( newElem, GETLINK( elemInList, pList->LinkOffset), pList->LinkOffset);
+ if ( lastElem) // somewhere past the head
+ {
+ ASSIGNLINK( lastElem, newElem, pList->LinkOffset);
+ }
+ else // at the head
+ {
+ pList->Head = newElem;
+ }
+ if ( pList->Tail == elemInList)
+ pList->Tail = newElem;
+ return 1;
+ }
+ lastElem = iElem;
+ }
+
+ return 0;
+}
+
+
+// GenDoubleLinkedList /////////////////////////////////////////////////////////
+
+void InitDoubleLinkedList( GenDoubleLinkedList *pList, size_t fwdLinkOffset,
+ size_t backLinkOffset)
+/* Initialize the block of memory pointed to by pList as a double linked list. */
+{
+ pList->Head = NULL;
+ pList->Tail = NULL;
+ pList->FwdLinkOffset = fwdLinkOffset;
+ pList->BackLinkOffset = backLinkOffset;
+}
+
+
+void DLLAddToHead( GenDoubleLinkedList *pList, void *elem)
+/* Add a linked list element to the head of the list. */
+{
+ void *pNext;
+
+ pNext = pList->Head;
+
+ // fix up the forward links
+ ASSIGNLINK( elem, pList->Head, pList->FwdLinkOffset);
+ pList->Head = elem;
+
+ // fix up the backward links
+ if ( pNext) {
+ ASSIGNLINK( pNext, elem, pList->BackLinkOffset);
+ } else
+ pList->Tail = elem;
+ ASSIGNLINK( elem, NULL, pList->BackLinkOffset);
+}
+
+
+void DLLRemoveFromList( GenDoubleLinkedList *pList, void *elem)
+/* Remove a linked list element from the list. */
+/* When the element is removed, its link will be set to NULL. */
+{
+ void *pNext, *pPrev;
+
+ pNext = GETLINK( elem, pList->FwdLinkOffset);
+ pPrev = GETLINK( elem, pList->BackLinkOffset);
+
+ // fix up the forward links
+ if ( pPrev)
+ ASSIGNLINK( pPrev, pNext, pList->FwdLinkOffset);
+ else
+ pList->Head = pNext;
+
+ // fix up the backward links
+ if ( pNext)
+ ASSIGNLINK( pNext, pPrev, pList->BackLinkOffset);
+ else
+ pList->Tail = pPrev;
+
+ ASSIGNLINK( elem, NULL, pList->FwdLinkOffset);
+ ASSIGNLINK( elem, NULL, pList->BackLinkOffset);
+}
+
+
+// GenLinkedOffsetList /////////////////////////////////////////////////////
+
+// Extract the Next offset from element
+#define GETOFFSET( e, o) ( *(size_t*)((char*) (e) + (o)) )
+
+static void AssignOffsetLink( void *elem, void *link, size_t linkOffset);
+
+
+static void AssignOffsetLink( void *elem, void *link, size_t linkOffset)
+// Assign link to elem as an offset from elem. Assign 0 to elem if link is NULL.
+{
+ GETOFFSET( elem, linkOffset) = link ? (size_t) link - (size_t) elem : 0;
+}
+
+
+void *GetHeadPtr( GenLinkedOffsetList *pList)
+/* Return a pointer to the head element of a list, or NULL if none. */
+{
+ return pList->Head ? ( (char*) (pList) + pList->Head) : NULL;
+}
+
+
+void *GetTailPtr( GenLinkedOffsetList *pList)
+/* Return a pointer to the tail element of a list, or NULL if none. */
+{
+ return pList->Tail ? ( (char*) (pList) + pList->Tail) : NULL;
+}
+
+
+void *GetOffsetLink( GenLinkedOffsetList *pList, void *elem)
+/* Return the link pointer contained within element e for pList, or NULL if it is 0. */
+{
+ size_t nextOffset;
+
+ nextOffset = GETOFFSET( elem, pList->LinkOffset);
+
+ return nextOffset ? (char*) elem + nextOffset : NULL;
+}
+
+
+void InitLinkedOffsetList( GenLinkedOffsetList *pList, size_t linkOffset)
+/* Initialize the block of memory pointed to by pList as a linked list. */
+{
+ pList->Head = 0;
+ pList->Tail = 0;
+ pList->LinkOffset = linkOffset;
+}
+
+
+void OffsetAddToTail( GenLinkedOffsetList *pList, void *elem)
+/* Add a linked list element to the tail of the list. */
+{
+ if ( pList->Tail) {
+ AssignOffsetLink( GetTailPtr( pList), elem, pList->LinkOffset);
+ } else
+ pList->Head = (size_t) elem - (size_t) pList;
+ AssignOffsetLink( elem, NULL, pList->LinkOffset);
+
+ pList->Tail = (size_t) elem - (size_t) pList;
+}
+
+
+void OffsetAddToHead( GenLinkedOffsetList *pList, void *elem)
+/* Add a linked list element to the head of the list. */
+{
+ AssignOffsetLink( elem, GetHeadPtr( pList), pList->LinkOffset);
+ if ( pList->Tail == 0)
+ pList->Tail = (size_t) elem - (size_t) pList;
+
+ pList->Head = (size_t) elem - (size_t) pList;
+}
+
+
+int OffsetRemoveFromList( GenLinkedOffsetList *pList, void *elem)
+/* Remove a linked list element from the list. Return 0 if it was not found. */
+/* If the element is removed, its link will be set to NULL. */
+{
+ void *iElem, *lastElem;
+
+ for ( iElem = GetHeadPtr( pList), lastElem = NULL; iElem;
+ iElem = GetOffsetLink( pList, iElem))
+ {
+ if ( iElem == elem) {
+ if ( lastElem) { // somewhere past the head
+ AssignOffsetLink( lastElem, GetOffsetLink( pList, elem), pList->LinkOffset);
+ } else { // at the head
+ iElem = GetOffsetLink( pList, elem);
+ pList->Head = iElem ? (size_t) iElem - (size_t) pList : 0;
+ }
+ if ( GetTailPtr( pList) == elem)
+ pList->Tail = lastElem ? (size_t) lastElem - (size_t) pList : 0;
+ AssignOffsetLink( elem, NULL, pList->LinkOffset); // maybe catch a stale reference bug.
+ return 1;
+ }
+ lastElem = iElem;
+ }
+
+ return 0;
+}
+
+
+int OffsetReplaceElem( GenLinkedOffsetList *pList, void *elemInList, void *newElem)
+/* Replace an element in the list with a new element, in the same position. */
+{
+ void *iElem, *lastElem;
+
+ if ( elemInList == NULL || newElem == NULL)
+ return 0;
+
+ for ( iElem = GetHeadPtr( pList), lastElem = NULL; iElem;
+ iElem = GetOffsetLink( pList, iElem))
+ {
+ if ( iElem == elemInList)
+ {
+ AssignOffsetLink( newElem, GetOffsetLink( pList, elemInList), pList->LinkOffset);
+ if ( lastElem) // somewhere past the head
+ {
+ AssignOffsetLink( lastElem, newElem, pList->LinkOffset);
+ }
+ else // at the head
+ {
+ pList->Head = (size_t) newElem - (size_t) pList;
+ }
+ if ( GetTailPtr( pList) == elemInList)
+ pList->Tail = (size_t) newElem - (size_t) pList;
+ return 1;
+ }
+ lastElem = iElem;
+ }
+
+ return 0;
+}
+
+
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