/* linkedlist.c
* This file set implements a generic linked list object. It can be used
* wherever a linke list is required.
*
* NOTE: we do not currently provide a constructor and destructor for the
* object itself as we assume it will always be part of another strucuture.
* Having a pointer to it, I think, does not really make sense but costs
* performance. Consequently, there is is llInit() and llDestroy() and they
* do what a constructor and destructur do, except for creating the
* linkedList_t structure itself.
*
* File begun on 2007-07-31 by RGerhards
*
* Copyright 2007 Rainer Gerhards and Adiscon GmbH.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* A copy of the GPL can be found in the file "COPYING" in this distribution.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "rsyslog.h"
#include "linkedlist.h"
/* Initialize an existing linkedList_t structure
* pKey destructor may be zero to take care of non-keyed lists.
*/
rsRetVal llInit(linkedList_t *pThis, rsRetVal (*pEltDestructor)(), rsRetVal (*pKeyDestructor)(void*), int (*pCmpOp)())
{
assert(pThis != NULL);
assert(pEltDestructor != NULL);
pThis->pEltDestruct = pEltDestructor;
pThis->pKeyDestruct = pKeyDestructor;
pThis->cmpOp = pCmpOp;
pThis->pKey = NULL;
pThis->iNumElts = 0;
pThis->pRoot = NULL;
pThis->pLast = NULL;
return RS_RET_OK;
};
/* llDestroyEltData - destroys a list element
* It is a separate function as the
* functionality is needed in multiple code-pathes.
*/
static rsRetVal llDestroyElt(linkedList_t *pList, llElt_t *pElt)
{
DEFiRet;
assert(pList != NULL);
assert(pElt != NULL);
/* we ignore errors during destruction, as we need to try
* free the element in any case.
*/
if(pElt->pData != NULL)
pList->pEltDestruct(pElt->pData);
if(pElt->pKey != NULL)
pList->pKeyDestruct(pElt->pKey);
free(pElt);
pList->iNumElts--; /* one less */
return iRet;
}
/* llDestroy - destroys a COMPLETE linkedList
*/
rsRetVal llDestroy(linkedList_t *pThis)
{
DEFiRet;
llElt_t *pElt;
llElt_t *pEltPrev;
assert(pThis != NULL);
pElt = pThis->pRoot;
while(pElt != NULL) {
pEltPrev = pElt;
pElt = pElt->pNext;
/* we ignore errors during destruction, as we need to try
* finish the linked list in any case.
*/
llDestroyElt(pThis, pEltPrev);
}
return iRet;
}
/* llDestroyRootElt - destroy the root element but otherwise
* keeps this list intact. -- rgerhards, 2007-08-03
*/
rsRetVal llDestroyRootElt(linkedList_t *pThis)
{
DEFiRet;
llElt_t *pPrev;
if(pThis->pRoot == NULL) {
ABORT_FINALIZE(RS_RET_EMPTY_LIST);
}
pPrev = pThis->pRoot;
if(pPrev->pNext == NULL) {
/* it was the only list element */
pThis->pLast = NULL;
pThis->pRoot = NULL;
} else {
/* there are other list elements */
pThis->pRoot = pPrev->pNext;
}
CHKiRet(llDestroyElt(pThis, pPrev));
finalize_it:
return iRet;
}
/* get next user data element of a linked list. The caller must also
* provide a "cookie" to the function. On initial call, it must be
* NULL. Other than that, the caller is not allowed to to modify the
* cookie. In the current implementation, the cookie is an actual
* pointer to the current list element, but this is nothing that the
* caller should rely on.
*/
rsRetVal llGetNextElt(linkedList_t *pThis, linkedListCookie_t *ppElt, void **ppUsr)
{
llElt_t *pElt;
DEFiRet;
assert(pThis != NULL);
assert(ppElt != NULL);
assert(ppUsr != NULL);
pElt = *ppElt;
pElt = (pElt == NULL) ? pThis->pRoot : pElt->pNext;
if(pElt == NULL) {
iRet = RS_RET_END_OF_LINKEDLIST;
} else {
*ppUsr = pElt->pData;
}
*ppElt = pElt;
return iRet;
}
/* return the key of an Elt
* rgerhards, 2007-09-11: note that ppDatea is actually a void**,
* but I need to make it a void* to avoid lots of compiler warnings.
* It will be converted later down in the code.
*/
rsRetVal llGetKey(llElt_t *pThis, void *ppData)
{
assert(pThis != NULL);
assert(ppData != NULL);
*(void**) ppData = pThis->pKey;
return RS_RET_OK;
}
/* construct a new llElt_t
*/
static rsRetVal llEltConstruct(llElt_t **ppThis, void *pKey, void *pData)
{
DEFiRet;
llElt_t *pThis;
assert(ppThis != NULL);
if((pThis = (llElt_t*) calloc(1, sizeof(llElt_t))) == NULL) {
ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
}
pThis->pKey = pKey;
pThis->pData = pData;
finalize_it:
*ppThis = pThis;
return iRet;
}
/* append a user element to the end of the linked list. This includes setting a key. If no
* key is desired, simply pass in a NULL pointer for it.
*/
rsRetVal llAppend(linkedList_t *pThis, void *pKey, void *pData)
{
llElt_t *pElt;
DEFiRet;
CHKiRet(llEltConstruct(&pElt, pKey, pData));
pThis->iNumElts++; /* one more */
if(pThis->pLast == NULL) {
pThis->pRoot = pElt;
} else {
pThis->pLast->pNext = pElt;
}
pThis->pLast = pElt;
finalize_it:
return iRet;
}
/* unlink a requested element. As we have singly-linked lists, the
* caller also needs to pass in the previous element (or NULL, if it is the
* root element).
* rgerhards, 2007-11-21
*/
static rsRetVal llUnlinkElt(linkedList_t *pThis, llElt_t *pElt, llElt_t *pEltPrev)
{
assert(pElt != NULL);
if(pEltPrev == NULL) { /* root element? */
pThis->pRoot = pElt->pNext;
} else { /* regular element */
pEltPrev->pNext = pElt->pNext;
}
if(pElt == pThis->pLast)
pThis->pLast = pEltPrev;
return RS_RET_OK;
}
/* unlinks and immediately deletes an element. Previous element must
* be given (or zero if the root element is to be deleted).
* rgerhards, 2007-11-21
*/
static rsRetVal llUnlinkAndDelteElt(linkedList_t *pThis, llElt_t *pElt, llElt_t *pEltPrev)
{
DEFiRet;
assert(pElt != NULL);
CHKiRet(llUnlinkElt(pThis, pElt, pEltPrev));
CHKiRet(llDestroyElt(pThis, pElt));
finalize_it:
return iRet;
}
/* find a user element based on the provided key - this is the
* internal variant, which also tracks the last element pointer
* before the found element. This is necessary to delete elements.
* NULL means there is no element in front of it, aka the found elt
* is the root elt.
* rgerhards, 2007-11-21
*/
static rsRetVal llFindElt(linkedList_t *pThis, void *pKey, llElt_t **ppElt, llElt_t **ppEltPrev)
{
DEFiRet;
llElt_t *pElt;
llElt_t *pEltPrev = NULL;
int bFound = 0;
assert(pThis != NULL);
assert(pKey != NULL);
assert(ppElt != NULL);
assert(ppEltPrev != NULL);
pElt = pThis->pRoot;
while(pElt != NULL && bFound == 0) {
if(pThis->cmpOp(pKey, pElt->pKey) == 0)
bFound = 1;
else {
pEltPrev = pElt;
pElt = pElt->pNext;
}
}
if(bFound == 1) {
*ppElt = pElt;
*ppEltPrev = pEltPrev;
} else
iRet = RS_RET_NOT_FOUND;
return iRet;
}
/* find a user element based on the provided key
*/
rsRetVal llFind(linkedList_t *pThis, void *pKey, void **ppData)
{
DEFiRet;
llElt_t *pElt;
llElt_t *pEltPrev;
CHKiRet(llFindElt(pThis, pKey, &pElt, &pEltPrev));
/* if we reach this point, we have found the element */
*ppData = pElt->pData;
finalize_it:
return iRet;
}
/* find a delete an element based on user-provided key. The element is
* delete, the caller does not receive anything. If we need to receive
* the element before destruction, we may implement an llFindAndUnlink()
* at that time.
* rgerhards, 2007-11-21
*/
rsRetVal llFindAndDelete(linkedList_t *pThis, void *pKey)
{
DEFiRet;
llElt_t *pElt;
llElt_t *pEltPrev;
CHKiRet(llFindElt(pThis, pKey, &pElt, &pEltPrev));
/* if we reach this point, we have found an element */
CHKiRet(llUnlinkAndDelteElt(pThis, pElt, pEltPrev));
finalize_it:
return iRet;
}
/* provide the count of linked list elements
*/
rsRetVal llGetNumElts(linkedList_t *pThis, int *piCnt)
{
DEFiRet;
assert(pThis != NULL);
assert(piCnt != NULL);
*piCnt = pThis->iNumElts;
return iRet;
}
/* execute a function on all list members. The functions receives a
* user-supplied parameter, which may be either a simple value
* or a pointer to a structure with more data. If the user-supplied
* function does not return RS_RET_OK, this function here terminates.
* rgerhards, 2007-08-02
* rgerhards, 2007-11-21: added functionality to delete a list element.
* If the called user function returns RS_RET_OK_DELETE_LISTENTRY the current element
* is deleted.
*/
rsRetVal llExecFunc(linkedList_t *pThis, rsRetVal (*pFunc)(void*, void*), void* pParam)
{
DEFiRet;
rsRetVal iRetLL;
void *pData;
linkedListCookie_t llCookie = NULL;
linkedListCookie_t llCookiePrev = NULL; /* previous list element (needed for deletion, NULL = at root) */
assert(pThis != NULL);
assert(pFunc != NULL);
while((iRetLL = llGetNextElt(pThis, &llCookie, (void**)&pData)) == RS_RET_OK) {
iRet = pFunc(pData, pParam);
if(iRet == RS_RET_OK_DELETE_LISTENTRY) {
/* delete element */
CHKiRet(llUnlinkAndDelteElt(pThis, llCookie, llCookiePrev));
/* we need to revert back, as we have just deleted the current element.
* So the actual current element is the one before it, which happens to be
* stored in llCookiePrev. -- rgerhards, 2007-11-21
*/
llCookie = llCookiePrev;
} else if (iRet != RS_RET_OK) {
goto finalize_it;
}
llCookiePrev = llCookie;
}
if(iRetLL != RS_RET_END_OF_LINKEDLIST)
iRet = iRetLL;
finalize_it:
return iRet;
}
/*
* vi:set ai:
*/
syntax highlighted by Code2HTML, v. 0.9.1