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windows-nt-4.0/private/sdktools/vctools/crt/crtw32/heap/realloc.c

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/***
*realloc.c - Reallocate a block of memory in the heap
*
* Copyright (c) 1989-1995, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the realloc() and _expand() functions.
*
*Revision History:
* 10-25-89 GJF Module created.
* 11-06-89 GJF Massively revised to handle 'tiling' and to properly
* update proverdesc.
* 11-10-89 GJF Added MTHREAD support.
* 11-17-89 GJF Fixed pblck validation (i.e., conditional call to
* _heap_abort())
* 12-18-89 GJF Changed header file name to heap.h, also added explicit
* _cdecl or _pascal to function defintions
* 12-20-89 GJF Removed references to plastdesc
* 01-04-90 GJF Fixed a couple of subtle and nasty bugs in _expand().
* 03-11-90 GJF Replaced _cdecl with _CALLTYPE1, added #include
* <cruntime.h> and removed #include <register.h>.
* 03-29-90 GJF Made _heap_expand_block() _CALLTYPE4.
* 07-25-90 SBM Replaced <stdio.h> by <stddef.h>, replaced
* <assertm.h> by <assert.h>
* 09-28-90 GJF New-style function declarators.
* 12-28-90 SRW Added cast of void * to char * for Mips C Compiler
* 03-05-91 GJF Changed strategy for rover - old version available
* by #define-ing _OLDROVER_.
* 04-08-91 GJF Temporary hack for Win32/DOS folks - special version
* of realloc that uses just malloc, _msize, memcpy and
* free. Change conditioned on _WIN32DOS_.
* 05-28-91 GJF Removed M_I386 conditionals and put in _WIN32_
* conditionals to build non-tiling heap for Win32.
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
* 08-06-93 SKS Fix bug in realloc() - if block cannot be expanded in
* place, and call to malloc() fails, the code in this
* routine was inadvertently freeing the sucessor block.
* Reported by Phar Lap TNT team after MSVCNT was final.
* 09-27-93 GJF Added checks of block size argument(s) against
* _HEAP_MAXREQ. Removed old _CRUISER_ and _WIN32DOS_
* support. Added some indenting to complicated exprs.
* 12-10-93 GJF Replace 4 (bytes) with _GRANULARITY.
* 03-02-94 GJF If _heap_split_block() returns failure, which it now
* can, return the untrimmed allocation block.
* 11-03-94 CFW Debug heap support.
* 12-01-94 CFW Use malloc with new handler.
* 02-06-95 CFW assert -> _ASSERTE.
* 02-07-95 GJF Merged in Mac version. Temporarily #ifdef-ed out the
* dbgint.h stuff. Removed obsolete _OLDROVER_ code.
* 02-09-95 GJF Restored *_base names.
* 05-01-95 GJF Spliced on winheap version.
* 05-08-95 CFW Changed new handler scheme.
* 05-22-95 GJF Test against _HEAP_MAXREQ before calling API.
* 05-24-95 CFW Official ANSI C++ new handler added.
*
*******************************************************************************/
#ifdef WINHEAP
#include <cruntime.h>
#include <malloc.h>
#include <winheap.h>
#include <windows.h>
#include <internal.h>
#include <dbgint.h>
/***
*void *realloc(void *pblock, size_t newsize) - reallocate a block of memory in
* the heap
*
*Purpose:
* Re-allocates a block in the heap to newsize bytes. newsize may be
* either greater or less than the original size of the block. The
* re-allocation may result in moving the block as well as changing
* the size. If the block is moved, the contents of the original block
* are copied over.
*
* Special ANSI Requirements:
*
* (1) realloc(NULL, newsize) is equivalent to malloc(newsize)
*
* (2) realloc(pblock, 0) is equivalent to free(pblock) (except that
* NULL is returned)
*
* (3) if the realloc() fails, the object pointed to by pblock is left
* unchanged
*
*Entry:
* void *pblock - pointer to block in the heap previously allocated
* by a call to malloc(), realloc() or _expand().
*
* size_t newsize - requested size for the re-allocated block
*
*Exit:
* Success: Pointer to the re-allocated memory block
* Failure: NULL
*
*Uses:
*
*Exceptions:
* If pblock does not point to a valid allocation block in the heap,
* realloc() will behave unpredictably and probably corrupt the heap.
*
*******************************************************************************/
void * __cdecl _realloc_base(
void * pblock,
size_t newsize
)
{
void * retp;
/* if ptr is NULL, call malloc */
if ( pblock == (void *) NULL )
return( _malloc_base( newsize ) );
/* if ptr is !NULL and size is 0, call free and return NULL */
if ( newsize == 0 ) {
_free_base( pblock );
return( (void *)NULL );
}
#ifdef HEAPHOOK
/* call heap hook if installed */
if (_heaphook) {
if ((*_heaphook)(_HEAP_REALLOC, newsize, pblock, (void *)&retp))
return retp;
}
#endif /* HEAPHOOK */
#ifndef _POSIX_
for (;;) {
#endif /* _POSIX_ */
/* validate size */
if ( newsize > _HEAP_MAXREQ )
retp = NULL; /* still call new handler */
else
retp = HeapReAlloc( _crtheap,
0,
pblock,
newsize
);
#ifdef _POSIX_
return retp;
#else /* _POSIX_ */
if ( retp || _newmode == 0)
return retp;
/* call installed new handler */
if (!_callnewh(newsize))
return NULL;
/* new handler was successful -- try to allocate again */
}
#endif /* ndef _POSIX_ */
}
#else /* ndef WINHEAP */
#include <cruntime.h>
#include <heap.h>
#include <malloc.h>
#include <mtdll.h>
#include <stddef.h>
#include <string.h>
#include <dbgint.h>
#if defined(_M_MPPC) || defined(_M_M68K)
#include <macos\memory.h> // Mac OS interface header
#endif
/* useful macro to compute the size of an allocation block given both a
* pointer to the descriptor and a pointer to the user area of the block
* (more efficient variant of _BLKSIZE macro, given the extra information)
*/
#define BLKSZ(pdesc_m,pblock_m) ((unsigned)_ADDRESS((pdesc_m)->pnextdesc) - \
(unsigned)(pblock_m))
/* expand an allocation block, in place, up to or beyond a specified size
* by coalescing it with subsequent free blocks (if possible)
*/
static int __cdecl _heap_expand_block(_PBLKDESC, size_t *, size_t);
#if defined(_M_MPPC) || defined(_M_M68K)
extern Handle hHeapRegions;
extern int _heap_region_table_cur;
#endif
/***
*void *realloc(void *pblock, size_t newsize) - reallocate a block of memory in
* the heap
*
*Purpose:
* Re-allocates a block in the heap to newsize bytes. newsize may be
* either greater or less than the original size of the block. The
* re-allocation may result in moving the block as well as changing
* the size. If the block is moved, the contents of the original block
* are copied over.
*
* Special ANSI Requirements:
*
* (1) realloc(NULL, newsize) is equivalent to malloc(newsize)
*
* (2) realloc(pblock, 0) is equivalent to free(pblock) (except that
* NULL is returned)
*
* (3) if the realloc() fails, the object pointed to by pblock is left
* unchanged
*
* Special Notes For Multi-thread: The heap is locked immediately prior
* to assigning pdesc. This is after special cases (1) and (2), listed
* above, are taken care of. The lock is released immediately prior to
* the final return statement.
*
*Entry:
* void *pblock - pointer to block in the heap previously allocated
* by a call to malloc(), realloc() or _expand().
*
* size_t newsize - requested size for the re-allocated block
*
*Exit:
* Success: Pointer to the re-allocated memory block
* Failure: NULL
*
*Uses:
*
*Exceptions:
* If pblock does not point to a valid allocation block in the heap,
* realloc() will behave unpredictably and probably corrupt the heap.
*
*******************************************************************************/
void * __cdecl _realloc_base (
REG1 void *pblock,
size_t newsize
)
{
REG2 _PBLKDESC pdesc;
_PBLKDESC pdesc2;
void *retp;
size_t oldsize;
size_t currsize;
/* special cases, handling mandated by ANSI
*/
if ( pblock == NULL )
/* just do a malloc of newsize bytes and return a pointer to
* the new block
*/
return( _malloc_base(newsize) );
if ( newsize == 0 ) {
/* free the block and return NULL
*/
_free_base(pblock);
return( NULL );
}
/* make newsize a valid allocation block size (i.e., round up to the
* nearest whole number of dwords)
*/
newsize = _ROUND2(newsize, _GRANULARITY);
#ifdef HEAPHOOK
/* call heap hook if installed */
if (_heaphook) {
if ((*_heaphook)(_HEAP_REALLOC, newsize, pblock, (void *)&retp))
return retp;
}
#endif /* HEAPHOOK */
/* if multi-thread support enabled, lock the heap here
*/
_mlock(_HEAP_LOCK);
/* set pdesc to point to the descriptor for *pblock
*/
pdesc = _BACKPTR(pblock);
if ( _ADDRESS(pdesc) != ((char *)pblock - _HDRSIZE) )
_heap_abort();
/* see if pblock is big enough already, or can be expanded (in place)
* to be big enough.
*/
if ( ((oldsize = currsize = BLKSZ(pdesc, pblock)) > newsize) ||
(_heap_expand_block(pdesc, &currsize, newsize) == 0) ) {
/* if necessary, mark pdesc as inuse
*/
if ( _IS_FREE(pdesc) ) {
_SET_INUSE(pdesc);
}
/* trim pdesc down to be exactly newsize bytes, if necessary
*/
if ( (currsize > newsize) &&
((pdesc2 = _heap_split_block(pdesc, newsize)) != NULL) )
{
_SET_FREE(pdesc2);
}
retp = pblock;
goto realloc_done;
}
/* try malloc-ing a new block of the requested size. if successful,
* copy over the data from the original block and free it.
*/
if ( (retp = _malloc_base(newsize)) != NULL ) {
memcpy(retp, pblock, oldsize);
_free_base_lk(pblock);
}
/* else if unsuccessful, return retp (== NULL) */
realloc_done:
/* if multi-thread support is enabled, unlock the heap here
*/
_munlock(_HEAP_LOCK);
return(retp);
}
/***
*void *_expand(void *pblock, size_t newsize) - expand/contract a block of memory
* in the heap
*
*Purpose:
* Resizes a block in the heap to newsize bytes. newsize may be either
* greater (expansion) or less (contraction) than the original size of
* the block. The block is NOT moved. In the case of expansion, if the
* block cannot be expanded to newsize bytes, it is expanded as much as
* possible.
*
* Special Notes For Multi-thread: The heap is locked just before pdesc
* is assigned and unlocked immediately prior to the return statement.
*
*Entry:
* void *pblock - pointer to block in the heap previously allocated
* by a call to malloc(), realloc() or _expand().
*
* size_t newsize - requested size for the resized block
*
*Exit:
* Success: Pointer to the resized memory block (i.e., pblock)
* Failure: NULL
*
*Uses:
*
*Exceptions:
* If pblock does not point to a valid allocation block in the heap,
* _expand() will behave unpredictably and probably corrupt the heap.
*
*******************************************************************************/
void * __cdecl _expand_base (
REG1 void *pblock,
size_t newsize
)
{
REG2 _PBLKDESC pdesc;
_PBLKDESC pdesc2;
void *retp;
size_t oldsize;
size_t currsize;
int index;
#if defined(_M_MPPC) || defined(_M_M68K)
struct _heap_region_ *pHeapRegions;
#endif
/* make newsize a valid allocation block size (i.e., round up to the
* nearest whole number of dwords)
*/
newsize = _ROUND2(newsize, _GRANULARITY);
#ifdef HEAPHOOK
/* call heap hook if installed */
if (_heaphook) {
if ((*_heaphook)(_HEAP_EXPAND, newsize, pblock, (void *)&retp))
return retp;
}
#endif /* HEAPHOOK */
retp = pblock;
/* validate size */
if ( newsize > _HEAP_MAXREQ )
newsize = _HEAP_MAXREQ;
/* if multi-thread support enabled, lock the heap here
*/
_mlock(_HEAP_LOCK);
/* set pdesc to point to the descriptor for *pblock
*/
pdesc = _BACKPTR(pblock);
/* see if pblock is big enough already, or can be expanded (in place)
* to be big enough.
*/
if ( ((oldsize = currsize = BLKSZ(pdesc, pblock)) >= newsize) ||
(_heap_expand_block(pdesc, &currsize, newsize) == 0) ) {
/* pblock is (now) big enough. trim it down, if necessary
*/
if ( (currsize > newsize) &&
((pdesc2 = _heap_split_block(pdesc, newsize)) != NULL) )
{
_SET_FREE(pdesc2);
currsize = newsize;
}
goto expand_done;
}
/* if the heap block is at the end of a region, attempt to grow the
* region
*/
if ( (pdesc->pnextdesc == &_heap_desc.sentinel) ||
_IS_DUMMY(pdesc->pnextdesc) ) {
/* look up the region index
*/
#if defined(_M_MPPC) || defined(_M_M68K)
pHeapRegions = (struct _heap_region_ *)(*hHeapRegions);
for ( index = 0 ; index < _heap_region_table_cur ; index++ )
if (((pHeapRegions + index)->_regbase < pblock) &&
(((char *)((pHeapRegions + index)->_regbase) +
(pHeapRegions + index)->_currsize) >= (char *)pblock) )
break;
#else
for ( index = 0 ; index < _HEAP_REGIONMAX ; index++ )
if ( (_heap_regions[index]._regbase < pblock) &&
(((char *)(_heap_regions[index]._regbase) +
_heap_regions[index]._currsize) >=
(char *)pblock) )
break;
#endif
/* make sure a valid region index was obtained (pblock could
* lie in a portion of heap memory donated by a user call to
* _heapadd(), which therefore would not appear in the region
* table)
*/
#if defined(_M_MPPC) || defined(_M_M68K)
if ( index == _heap_region_table_cur ) {
#else
if ( index == _HEAP_REGIONMAX ) {
#endif
retp = NULL;
goto expand_done;
}
/* try growing the region. the difference between newsize and
* the current size of the block, rounded up to the nearest
* whole number of pages, is the amount the region needs to
* be grown. if successful, try expanding the block again
*/
if ( (_heap_grow_region(index, _ROUND2(newsize - currsize,
_PAGESIZE_)) == 0) &&
(_heap_expand_block(pdesc, &currsize, newsize) == 0) )
{
/* pblock is (now) big enough. trim it down to be
* exactly size bytes, if necessary
*/
if ( (currsize > newsize) && ((pdesc2 =
_heap_split_block(pdesc, newsize)) != NULL) )
{
_SET_FREE(pdesc2);
currsize = newsize;
}
}
else
retp = NULL;
}
else
retp = NULL;
expand_done:
/* if multi-thread support is enabled, unlock the heap here
*/
_munlock(_HEAP_LOCK);
return(retp);
}
/***
*int _heap_expand_block(pdesc, pcurrsize, newsize) - expand an allocation block
* in place (without trying to 'grow' the heap)
*
*Purpose:
*
*Entry:
* _PBLKDESC pdesc - pointer to the allocation block descriptor
* size_t *pcurrsize - pointer to size of the allocation block (i.e.,
* *pcurrsize == _BLKSIZE(pdesc), on entry)
* size_t newsize - requested minimum size for the expanded allocation
* block (i.e., newsize >= _BLKSIZE(pdesc), on exit)
*
*Exit:
* Success: 0
* Failure: -1
* In either case, *pcurrsize is updated with the new size of the block
*
*Exceptions:
* It is assumed that pdesc points to a valid allocation block descriptor.
* It is also assumed that _BLKSIZE(pdesc) == *pcurrsize on entry. If
* either of these assumptions is violated, _heap_expand_block will almost
* certainly trash the heap.
*
*******************************************************************************/
static int __cdecl _heap_expand_block (
REG1 _PBLKDESC pdesc,
REG3 size_t *pcurrsize,
size_t newsize
)
{
REG2 _PBLKDESC pdesc2;
_ASSERTE(("_heap_expand_block: bad pdesc arg", _CHECK_PDESC(pdesc)));
_ASSERTE(("_heap_expand_block: bad pcurrsize arg", *pcurrsize == _BLKSIZE(pdesc)));
for ( pdesc2 = pdesc->pnextdesc ; _IS_FREE(pdesc2) ;
pdesc2 = pdesc->pnextdesc ) {
/* coalesce with pdesc. check for special case of pdesc2
* being proverdesc.
*/
pdesc->pnextdesc = pdesc2->pnextdesc;
if ( pdesc2 == _heap_desc.proverdesc )
_heap_desc.proverdesc = pdesc;
/* update *pcurrsize, place *pdesc2 on the empty descriptor
* list and see if the coalesced block is now big enough
*/
*pcurrsize += _MEMSIZE(pdesc2);
_PUTEMPTY(pdesc2)
}
if ( *pcurrsize >= newsize )
return(0);
else
return(-1);
}
#endif /* WINHEAP */