/***
*realloc.c - Reallocate a block of memory in the heap
*
* Copyright (c) 1989-1991, 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.
*
*******************************************************************************/
#ifndef _WIN32DOS_
#include <cruntime.h>
#include <assert.h>
#include <heap.h>
#include <malloc.h>
#include <os2dll.h>
#include <stddef.h>
#include <string.h>
/* 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,pblk) ((unsigned)_ADDRESS((pdesc)->pnextdesc) - \
(unsigned)(pblck))
/* expand an allocation block, in place, up to or beyond a specified size
* by coalescing it with subsequent free blocks (if possible)
*/
static int _CALLTYPE4 _heap_expand_block(_PBLKDESC, size_t *, size_t);
/***
*void *realloc(void *pblck, 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(pblck, 0) is equivalent to free(pblck) (except that
* NULL is returned)
*
* (3) if the realloc() fails, the object pointed to by pblck is left
* unchanged
*
* Special Notes For Cruiser Implementaton: For OS/2 2.0, realloc() is
* required to ensure that the re-allocated block does not cross a 64 Kb
* boundary unless the new size is more than 64 Kb or the original block
* already crossed such a boundary.
*
* 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 *pblck - 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 pblck does not point to a valid allocation block in the heap,
* realloc() will behave unpredictably and probably corrupt the heap.
*
*******************************************************************************/
void * _CALLTYPE1 realloc (
REG1 void *pblck,
size_t newsize
)
{
REG2 _PBLKDESC pdesc;
void *pretblck;
size_t oldsize;
size_t currsize;
/* special cases, handling mandated by ANSI
*/
if ( pblck == NULL )
/* just do a malloc of newsize bytes and return a pointer to
* the new block
*/
return( malloc(newsize) );
if ( newsize == 0 ) {
/* free the block and return NULL
*/
free(pblck);
return( NULL );
}
/* make newsize a valid allocation block size (i.e., round up to the
* nearest whole number of dwords)
*/
newsize = _ROUND2(newsize,4);
/* if multi-thread support enabled, lock the heap here
*/
_mlock(_HEAP_LOCK);
/* set pdesc to point to the descriptor for *pblck
*/
pdesc = _BACKPTR(pblck);
if ( _ADDRESS(pdesc) != ((char *)pblck - _HDRSIZE) )
_heap_abort();
/* see if pblck is big enough already, or can be expanded (in place)
* to be big enough.
*/
#ifdef _CRUISER_
/* if the block was expanded in place, ensure that it does not cross
* a 64 Kb boundary unless it already did so or newsize is greater
* than 64 Kb
*/
if ( ((oldsize = currsize = BLKSZ(pdesc, pblck)) >= newsize) ||
((_heap_expand_block(pdesc, &currsize, newsize) == 0) &&
((newsize > _SEGSIZE_) || (_DISTTOBNDRY(pdesc) >= newsize) ||
(_DISTTOBNDRY(pdesc) < oldsize))) ) {
#else /* ndef _CRUISER_ */
#ifdef _WIN32_
if ( ((oldsize = currsize = BLKSZ(pdesc, pblck)) > newsize) ||
(_heap_expand_block(pdesc, &currsize, newsize) == 0) ) {
#else /* ndef _WIN32_ */
#error ERROR - ONLY CRUISER OR WIN32 TARGET SUPPORTED!
#endif /* _WIN32_ */
#endif /* _CRUISER_ */
/* if necessary, mark pdesc as inuse
*/
if ( _IS_FREE(pdesc) ) {
_SET_INUSE(pdesc);
#ifdef _OLDROVER_
_heap_advance_rover();
#endif /* _OLDROVER_ */
}
/* trim pdesc down to be exactly newsize bytes, if necessary
*/
if ( currsize > newsize ) {
_heap_split_block(pdesc, newsize);
_free_lk((char *)pblck + newsize + _HDRSIZE);
}
pretblck = pblck;
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 ( (pretblck = _malloc_lk(newsize)) != NULL ) {
memcpy(pretblck, pblck, oldsize);
_free_lk(pblck);
}
else {
/* restore pblck to its orignal size
*/
_heap_split_block(pdesc, oldsize);
_free_lk((char *)pblck + oldsize + _HDRSIZE);
}
realloc_done:
/* if multi-thread support is enabled, unlock the heap here
*/
_munlock(_HEAP_LOCK);
return(pretblck);
}
/***
*void *_expand(void *pblck, 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 Cruiser Implementaton: For OS/2 2.0, _expand() is
* required to ensure the resized block does not cross a 64 Kb boundary
* unless the requested new size is more than 64 Kb or the block already
* did so. Note that, because of the peculiar semantics of _expand(), it
* may produce block of less than 64 Kb in size which does cross a 64 Kb
* boundary.
*
* Special Notes For Multi-thread: The heap is locked just before pdesc
* is assigned and unlocked immediately prior to the return statement.
*
*Entry:
* void *pblck - 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., pblck)
* Failure: NULL
*
*Uses:
*
*Exceptions:
* If pblck does not point to a valid allocation block in the heap,
* _expand() will behave unpredictably and probably corrupt the heap.
*
*******************************************************************************/
void * _CALLTYPE1 _expand (
REG1 void *pblck,
size_t newsize
)
{
REG2 _PBLKDESC pdesc;
void *pretblck = pblck;
size_t oldsize;
size_t currsize;
unsigned index;
#ifdef _CRUISER_
size_t dist;
#endif /* _CRUISER_ */
/* make newsize a valid allocation block size (i.e., round up to the
* nearest whole number of dwords)
*/
newsize = _ROUND2(newsize,4);
/* if multi-thread support enabled, lock the heap here
*/
_mlock(_HEAP_LOCK);
/* set pdesc to point to the descriptor for *pblck
*/
pdesc = _BACKPTR(pblck);
/* see if pblck is big enough already, or can be expanded (in place)
* to be big enough.
*/
if ( ((oldsize = currsize = BLKSZ(pdesc, pblck)) >= newsize) ||
(_heap_expand_block(pdesc, &currsize, newsize) == 0) ) {
/* pblck is (now) big enough. trim it down, if necessary
*/
if ( currsize > newsize ) {
_heap_split_block(pdesc, newsize);
_free_lk((char *)pblck + newsize + _HDRSIZE);
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
*/
for ( index = 0 ; index < _HEAP_REGIONMAX ; index++ )
if ( (_heap_regions[index]._regbase < pblck) &&
(((char *)(_heap_regions[index]._regbase) +
_heap_regions[index]._currsize) >= (char *)pblck) )
break;
/* make sure a valid region index was obtained (pblck 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 ( index == _HEAP_REGIONMAX ) {
pretblck = 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) ) {
/* pblck is (now) big enough. trim it down to be
* exactly size bytes, if necessary
*/
if ( currsize > newsize ) {
_heap_split_block(pdesc, newsize);
_free_lk((char *)pblck + newsize + _HDRSIZE);
currsize = newsize;
}
}
else
pretblck = NULL;
}
else
pretblck = NULL;
expand_done:
#ifdef _CRUISER_
/* check for crossing of 64 Kb boundaries. the resized allocation
* block must be trimmed down if the following conditions all hold
* true:
* (1) the block was grown
* (2) the requested new size was less than 64 Kb
* (3) the block now crosses a 64 Kb boundary
* (4) the block did not originally cross a 64 Kb
* boundary
*/
if ( (currsize > oldsize) && (newsize <= _SEGSIZE_) &&
(currsize > (dist = _DISTTOBNDRY(pblck))) && (oldsize <= dist) ) {
_heap_split_block(pdesc, dist);
_free_lk((char *)pblck + dist + _HDRSIZE);
pretblck = NULL;
}
#endif /* _CRUISER_ */
/* if multi-thread support is enabled, unlock the heap here
*/
_munlock(_HEAP_LOCK);
return(pretblck);
}
/***
*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 _CALLTYPE4 _heap_expand_block (
REG1 _PBLKDESC pdesc,
REG3 size_t *pcurrsize,
size_t newsize
)
{
REG2 _PBLKDESC pdesc2;
assert(("_heap_expand_block: bad pdesc arg", _CHECK_PDESC(pdesc)));
assert(("_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 )
#ifdef _OLDROVER_
/* temporarily set proverdesc to pdesc
*/
#endif /* _OLDROVER_ */
_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)
}
#ifdef _OLDROVER_
if ( pdesc == _heap_desc.proverdesc )
_heap_advance_rover();
#endif /* _OLDROVER_ */
if ( *pcurrsize >= newsize )
return(0);
else
return(-1);
}
#else /* _WIN32DOS_ */
/*
* TEMPORARY HACK! THE CODE BELOW IS INTENDED TO ALLOW LIMITED USE OF THE
* C RUNTIME ON WIN32/DOS. IT WILL BE DELETED AS SOON AS THEY IMPLEMENT
* VirtualAlloc()!
*/
#include <cruntime.h>
#include <malloc.h>
#include <stdlib.h>
#include <string.h>
void * _CALLTYPE1 realloc (
REG1 void *pblck,
size_t newsize
)
{
void *pnew;
size_t oldsize;
if ( (pnew = malloc(newsize)) != NULL ) {
oldsize = _msize(pblck);
memcpy(pnew, pblck, min(newsize, oldsize));
free(pblck);
}
return pnew;
}
#endif /* _WIN32DOS_ */
