07d0bddb4f
It's possible for another invocation to increase the array size in between the ReadUnlock and WriteLock calls, causing the 'i' index to refer to a taken entry.
104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/**
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* OpenAL cross platform audio library
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* Copyright (C) 1999-2007 by authors.
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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 Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 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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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* Or go to http://www.gnu.org/copyleft/lgpl.html
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*/
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#include "config.h"
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#include <stdlib.h>
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#include "alMain.h"
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#include "alThunk.h"
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static ATOMIC(ALenum) *ThunkArray;
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static ALuint ThunkArraySize;
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static RWLock ThunkLock;
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void ThunkInit(void)
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{
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RWLockInit(&ThunkLock);
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ThunkArraySize = 1;
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ThunkArray = al_calloc(16, ThunkArraySize * sizeof(*ThunkArray));
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}
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void ThunkExit(void)
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{
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al_free(ThunkArray);
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ThunkArray = NULL;
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ThunkArraySize = 0;
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}
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ALenum NewThunkEntry(ALuint *index)
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{
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void *NewList;
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ALuint i;
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ReadLock(&ThunkLock);
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for(i = 0;i < ThunkArraySize;i++)
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{
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if(ATOMIC_EXCHANGE(ALenum, &ThunkArray[i], AL_TRUE) == AL_FALSE)
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{
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ReadUnlock(&ThunkLock);
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*index = i+1;
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return AL_NO_ERROR;
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}
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}
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ReadUnlock(&ThunkLock);
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WriteLock(&ThunkLock);
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/* Double-check that there's still no free entries, in case another
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* invocation just came through and increased the size of the array.
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*/
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for(;i < ThunkArraySize;i++)
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{
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if(ATOMIC_EXCHANGE(ALenum, &ThunkArray[i], AL_TRUE) == AL_FALSE)
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{
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WriteUnlock(&ThunkLock);
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*index = i+1;
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return AL_NO_ERROR;
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}
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}
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NewList = al_calloc(16, ThunkArraySize*2 * sizeof(*ThunkArray));
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if(!NewList)
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{
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WriteUnlock(&ThunkLock);
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ERR("Realloc failed to increase to %u entries!\n", ThunkArraySize*2);
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return AL_OUT_OF_MEMORY;
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}
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memcpy(NewList, ThunkArray, ThunkArraySize*sizeof(*ThunkArray));
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al_free(ThunkArray);
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ThunkArray = NewList;
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ThunkArraySize *= 2;
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ATOMIC_STORE(&ThunkArray[i], AL_TRUE);
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WriteUnlock(&ThunkLock);
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*index = i+1;
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return AL_NO_ERROR;
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}
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void FreeThunkEntry(ALuint index)
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{
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ReadLock(&ThunkLock);
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if(index > 0 && index <= ThunkArraySize)
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ATOMIC_STORE(&ThunkArray[index-1], AL_FALSE);
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ReadUnlock(&ThunkLock);
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}
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