93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
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/***
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*expand.c - Win32 expand heap routine
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*
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* Copyright (c) 1991-1992, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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*
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*Revision History:
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* 01-15-92 JCR Module created.
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* 02-04-92 GJF Replaced windows.h with oscalls.h.
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* 05-06-92 DJM ifndef out of POSIX build.
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* 09-23-92 SRW Change winheap code to call NT directly always
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* 10-15-92 SKS Removed the ill-named HEAP_GROWTH_ALLOWED flag
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* which was causing a bug: _expand was behaving like
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* realloc(), by moving the block when it could not be
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* grown in place. _expand() must NEVER move the block.
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* Also added a safety check to work around a bug in
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* HeapReAlloc, where it returns success even
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* when it fails to grow the block in place.
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* 10-28-92 SRW Change winheap code to call Heap????Ex calls
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* 11-05-92 SKS Change name of variable "CrtHeap" to "_crtheap"
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* 11-07-92 SRW _NTIDW340 replaced by linkopts\betacmp.c
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* 11-16-92 SRW Heap???Ex functions renamed to Heap???
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*
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*******************************************************************************/
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#ifndef _POSIX_
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#include <cruntime.h>
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#include <malloc.h>
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#include <winheap.h>
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#include <oscalls.h>
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/***
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*void *_expand(void *pblck, size_t newsize) - expand/contract a block of memory
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* in the heap
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*
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*Purpose:
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* Resizes a block in the heap to newsize bytes. newsize may be either
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* greater (expansion) or less (contraction) than the original size of
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* the block. The block is NOT moved.
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*
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* NOTES:
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*
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* (1) In this implementation, if the block cannot be grown to the
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* desired size, the resulting block will NOT be grown to the max
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* possible size. (That is, either it works or it doesn't.)
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*
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* (2) Unlike other implementations, you can NOT pass a previously
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* freed block to this routine and expect it to work.
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*
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*Entry:
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* void *pblck - pointer to block in the heap previously allocated
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* by a call to malloc(), realloc() or _expand().
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*
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* size_t newsize - requested size for the resized block
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*
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*Exit:
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* Success: Pointer to the resized memory block (i.e., pblck)
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* Failure: NULL
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*
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*Uses:
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*
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*Exceptions:
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* If pblck does not point to a valid allocation block in the heap,
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* _expand() will behave unpredictably and probably corrupt the heap.
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*
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*******************************************************************************/
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void * _CALLTYPE1 _expand(pblock, n)
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void * pblock;
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size_t n;
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{
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void * p;
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p = HeapReAlloc(_crtheap,
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HEAP_REALLOC_IN_PLACE_ONLY,
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pblock,
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n ? n : 1
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);
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/**
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* Temporary BUG work-around:
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* HeapReAlloc sometimes (often?) returns success
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* even when there has been a failure to grow in place.
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* This conditional will recognize this case and handle it.
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**/
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return ( p == pblock ) && ( _msize(pblock) >= n ) ? pblock : NULL;
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}
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#endif /* !_POSIX_ */
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