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190 lines
5.3 KiB
C
190 lines
5.3 KiB
C
/* Copyright (c) 2003 Juan Lang
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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*
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* This implementation uses a linked list, because I don't have a decent
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* hash table implementation handy. This is somewhat inefficient, but it's
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* rather more efficient than not having a name cache at all.
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*/
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#include "config.h"
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#include "wine/port.h"
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#include "nbnamecache.h"
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typedef struct _NBNameCacheNode
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{
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DWORD expireTime;
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NBNameCacheEntry *entry;
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struct _NBNameCacheNode *next;
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} NBNameCacheNode;
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struct NBNameCache
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{
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HANDLE heap;
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CRITICAL_SECTION cs;
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DWORD entryExpireTimeMS;
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NBNameCacheNode *head;
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};
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/* Unlinks the node pointed to by *prev, and frees any associated memory.
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* If that node's next pointed to another node, *prev now points to it.
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* Assumes the caller owns cache's lock.
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*/
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static void NBNameCacheUnlinkNode(struct NBNameCache *cache,
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NBNameCacheNode **prev)
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{
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if (cache && prev && *prev)
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{
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NBNameCacheNode *next = (*prev)->next;
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HeapFree(cache->heap, 0, (*prev)->entry);
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HeapFree(cache->heap, 0, *prev);
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*prev = next;
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}
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}
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/* Walks the list beginning with cache->head looking for the node with name
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* name. If the node is found, returns a pointer to the next pointer of the
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* node _prior_ to the found node (or head if head points to it). Thus, if the
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* node's all you want, dereference the return value twice. If you want to
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* modify the list, modify the referent of the return value.
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* While it's at it, deletes nodes whose time has expired (except the node
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* you're looking for, of course).
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* Returns NULL if the node isn't found.
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* Assumes the caller owns cache's lock.
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*/
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static NBNameCacheNode **NBNameCacheWalk(struct NBNameCache *cache,
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const char name[NCBNAMSZ])
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{
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NBNameCacheNode **ret = NULL;
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if (cache && cache->head)
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{
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NBNameCacheNode **ptr;
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ptr = &cache->head;
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while (ptr && *ptr && (*ptr)->entry)
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{
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if (!memcmp((*ptr)->entry->name, name, NCBNAMSZ - 1))
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ret = ptr;
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else
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{
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if (GetTickCount() > (*ptr)->expireTime)
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NBNameCacheUnlinkNode(cache, ptr);
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}
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if (*ptr)
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ptr = &(*ptr)->next;
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}
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}
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return ret;
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}
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struct NBNameCache *NBNameCacheCreate(HANDLE heap, DWORD entryExpireTimeMS)
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{
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struct NBNameCache *cache;
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if (!heap)
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heap = GetProcessHeap();
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cache = HeapAlloc(heap, 0, sizeof(struct NBNameCache));
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if (cache)
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{
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cache->heap = heap;
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InitializeCriticalSection(&cache->cs);
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cache->cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NBNameCache.cs");
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cache->entryExpireTimeMS = entryExpireTimeMS;
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cache->head = NULL;
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}
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return cache;
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}
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BOOL NBNameCacheAddEntry(struct NBNameCache *cache, NBNameCacheEntry *entry)
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{
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BOOL ret;
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if (cache && entry)
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{
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NBNameCacheNode **node;
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EnterCriticalSection(&cache->cs);
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node = NBNameCacheWalk(cache, (char*)entry->name);
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if (node)
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{
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(*node)->expireTime = GetTickCount() +
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cache->entryExpireTimeMS;
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HeapFree(cache->heap, 0, (*node)->entry);
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(*node)->entry = entry;
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ret = TRUE;
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}
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else
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{
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NBNameCacheNode *newNode = HeapAlloc(cache->heap, 0, sizeof(NBNameCacheNode));
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if (newNode)
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{
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newNode->expireTime = GetTickCount() +
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cache->entryExpireTimeMS;
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newNode->entry = entry;
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newNode->next = cache->head;
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cache->head = newNode;
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ret = TRUE;
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}
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else
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ret = FALSE;
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}
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LeaveCriticalSection(&cache->cs);
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}
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else
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ret = FALSE;
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return ret;
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}
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const NBNameCacheEntry *NBNameCacheFindEntry(struct NBNameCache *cache,
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const UCHAR name[NCBNAMSZ])
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{
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const NBNameCacheEntry *ret;
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UCHAR printName[NCBNAMSZ];
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memcpy(printName, name, NCBNAMSZ - 1);
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printName[NCBNAMSZ - 1] = '\0';
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if (cache)
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{
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NBNameCacheNode **node;
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EnterCriticalSection(&cache->cs);
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node = NBNameCacheWalk(cache, (const char *)name);
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if (node)
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ret = (*node)->entry;
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else
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ret = NULL;
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LeaveCriticalSection(&cache->cs);
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}
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else
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ret = NULL;
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return ret;
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}
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void NBNameCacheDestroy(struct NBNameCache *cache)
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{
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if (cache)
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{
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cache->cs.DebugInfo->Spare[0] = 0;
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DeleteCriticalSection(&cache->cs);
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while (cache->head)
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NBNameCacheUnlinkNode(cache, &cache->head);
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HeapFree(cache->heap, 0, cache);
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}
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}
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