projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| bb2109e7 | 1 | /* |
| 4f703748 KB |
2 | * Copyright (c) 1988, 1989, 1990, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. | |
| c65fedcf | 4 | * |
| bb2109e7 KB |
5 | * This code is derived from software contributed to Berkeley by |
| 6 | * Adam de Boor. | |
| c65fedcf | 7 | * |
| f15db449 | 8 | * %sccs.include.redist.c% |
| c65fedcf | 9 | */ |
| bb2109e7 | 10 | |
| c65fedcf | 11 | #ifndef lint |
| bfdbffbb | 12 | static char sccsid[] = "@(#)lstRemove.c 8.2 (Berkeley) %G%"; |
| bb2109e7 KB |
13 | #endif /* not lint */ |
| 14 | ||
| 15 | /*- | |
| 16 | * LstRemove.c -- | |
| 17 | * Remove an element from a list | |
| 18 | */ | |
| c65fedcf KB |
19 | |
| 20 | #include "lstInt.h" | |
| 21 | ||
| 22 | /*- | |
| 23 | *----------------------------------------------------------------------- | |
| 24 | * Lst_Remove -- | |
| 25 | * Remove the given node from the given list. | |
| 26 | * | |
| 27 | * Results: | |
| 28 | * SUCCESS or FAILURE. | |
| 29 | * | |
| 30 | * Side Effects: | |
| 31 | * The list's firstPtr will be set to NilListNode if ln is the last | |
| 32 | * node on the list. firsPtr and lastPtr will be altered if ln is | |
| 33 | * either the first or last node, respectively, on the list. | |
| 34 | * | |
| 35 | *----------------------------------------------------------------------- | |
| 36 | */ | |
| 37 | ReturnStatus | |
| 38 | Lst_Remove (l, ln) | |
| 39 | Lst l; | |
| 40 | LstNode ln; | |
| 41 | { | |
| 42 | register List list = (List) l; | |
| 43 | register ListNode lNode = (ListNode) ln; | |
| 44 | ||
| 45 | if (!LstValid (l) || | |
| 46 | !LstNodeValid (ln, l)) { | |
| 47 | return (FAILURE); | |
| 48 | } | |
| 49 | ||
| 50 | /* | |
| 51 | * unlink it from the list | |
| 52 | */ | |
| 53 | if (lNode->nextPtr != NilListNode) { | |
| 54 | lNode->nextPtr->prevPtr = lNode->prevPtr; | |
| 55 | } | |
| 56 | if (lNode->prevPtr != NilListNode) { | |
| 57 | lNode->prevPtr->nextPtr = lNode->nextPtr; | |
| 58 | } | |
| 59 | ||
| 60 | /* | |
| 61 | * if either the firstPtr or lastPtr of the list point to this node, | |
| 62 | * adjust them accordingly | |
| 63 | */ | |
| 64 | if (list->firstPtr == lNode) { | |
| 65 | list->firstPtr = lNode->nextPtr; | |
| 66 | } | |
| 67 | if (list->lastPtr == lNode) { | |
| 68 | list->lastPtr = lNode->prevPtr; | |
| 69 | } | |
| 70 | ||
| 71 | /* | |
| 72 | * Sequential access stuff. If the node we're removing is the current | |
| 73 | * node in the list, reset the current node to the previous one. If the | |
| 74 | * previous one was non-existent (prevPtr == NilListNode), we set the | |
| 75 | * end to be Unknown, since it is. | |
| 76 | */ | |
| 77 | if (list->isOpen && (list->curPtr == lNode)) { | |
| 78 | list->curPtr = list->prevPtr; | |
| 79 | if (list->curPtr == NilListNode) { | |
| 80 | list->atEnd = Unknown; | |
| 81 | } | |
| 82 | } | |
| 83 | ||
| 84 | /* | |
| 85 | * the only way firstPtr can still point to ln is if ln is the last | |
| 86 | * node on the list (the list is circular, so lNode->nextptr == lNode in | |
| 87 | * this case). The list is, therefore, empty and is marked as such | |
| 88 | */ | |
| 89 | if (list->firstPtr == lNode) { | |
| 90 | list->firstPtr = NilListNode; | |
| 91 | } | |
| 92 | ||
| 93 | /* | |
| 94 | * note that the datum is unmolested. The caller must free it as | |
| 95 | * necessary and as expected. | |
| 96 | */ | |
| 97 | if (lNode->useCount == 0) { | |
| 98 | free ((Address)ln); | |
| 99 | } else { | |
| 100 | lNode->flags |= LN_DELETED; | |
| 101 | } | |
| 102 | ||
| 103 | return (SUCCESS); | |
| 104 | } | |
| 105 |