/***
*malloc.c - Get a block of memory from the heap
*
* Copyright (c) 1989-1995, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the malloc() function. Also defines the internal utility
* functions _flat_malloc(), _heap_split_block(), _heap_advance_rover()
* and, for multi-thread, _malloc_lk().
*
*Revision History:
* 06-29-89 GJF Module created (no rest for the wicked).
* 07-07-89 GJF Several bug fixes
* 07-21-89 GJF Added code to maintain proverdesc such that proverdesc
* either points to the descriptor for the first free
* block in the heap or, if there are no free blocks, is
* the same as plastdesc.
* 11-07-89 GJF Substantially revised to cope with 'tiling'.
* 11-09-89 GJF Embarrassing bug (didn't bother to assign pdesc)
* 11-10-89 GJF Added MTHREAD support.
* 11-17-89 GJF Oops, must call _free_lk() instead of free()!
* 12-18-89 GJF Changed name of header file to heap.h, also added
* explicit _cdecl to function definitions.
* 12-19-89 GJF Got rid of plastdesc from _heap_split_block() and
* _heap_advance_rover().
* 03-11-90 GJF Replaced _cdecl with _CALLTYPE1, added #include
* <cruntime.h> and removed #include <register.h>.
* 07-25-90 SBM Replaced <stdio.h> by <stddef.h>, replaced
* <assertm.h> by <assert.h>
* 09-28-90 GJF New-style function declarators.
* 02-26-91 SRW Optimize heap rover for _WIN32_.
* 03-07-91 FAR Fix bug in heap rover
* 03-11-91 FAR REALLY Fix bug in heap rover
* 03-14-91 GJF Changed strategy for rover - old version available
* by #define-ing _OLDROVER_.
* 04-05-91 GJF Temporary hack for Win32/DOS folks - special version
* of malloc that just calls HeapAlloc. Change conditioned
* on _WIN32DOS_.
* 05-28-91 GJF Removed M_I386 conditionals and put in _CRUISER_
* conditionals so the 'tiling' version is built only for
* Cruiser.
* 03-03-93 SKS Add new handler support (_pnhHeap and related code)
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
* 09-22-93 GJF Turned on range check. Also, removed old Cruiser
* support.
* 12-09-93 GJF Replace 4 (bytes) with _GRANULARITY.
* 02-16-94 SKS Move set_new_handler support to new() in new.cxx
* 03-01-94 SKS Declare _pnhHeap, pointer to the new handler, here
* 03-02-94 GJF Changed logic of, and interface to, _heap_split_block
* so that it may fail for lack of a free descriptor.
* Also, changed malloc() so that the too-large block is
* returned to the caller when _heap_split_block fails.
* 03-03-94 SKS Reimplement new() handling within malloc - new scheme
* allows the new() handler to be called optionally on
* malloc failures. _set_new_mode(1) enables the option.
* 03-04-94 SKS Rename _nhMode to _newmode, move it to its own module.
* 03-02-94 GJF Changed logic of, and interface to, _heap_split_block
* so that it may fail for lack of a free descriptor.
* Also, changed malloc() so that the too-large block is
* returned to the caller when _heap_split_block fails.
* 04-01-94 GJF Made definition of _pnhHeap and declaration of
* _newmode conditional on DLL_FOR_WIN32S.
* 11-03-94 CFW Debug heap support.
* 12-01-94 CFW Simplify debug interface.
* 02-06-95 CFW assert -> _ASSERTE.
* 02-07-95 GJF Deleted _OLDROVER_ code (obsolete). Also made some
* temporary, conditional changes so this file can be
* used in the MAC builds.
* 02-09-95 GJF Restored *_base names.
* 05-01-95 GJF Spliced on winheap version.
* 05-24-95 CFW Official ANSI C++ new handler added.
* 06-23-95 CFW ANSI new handler removed, fix block size check.
*
*******************************************************************************/
#include <cruntime.h>
#include <malloc.h>
#include <internal.h>
#include <mtdll.h>
#include <dbgint.h>
#ifdef WINHEAP
#include <windows.h>
#include <winheap.h>
#else
#include <heap.h>
#endif
#ifndef _POSIX_
#ifndef DLL_FOR_WIN32S
extern int _newmode; /* malloc new() handler mode */
#endif /* DLL_FOR_WIN32S */
#endif /* _POSIX_ */
/***
*void *malloc(size_t size) - Get a block of memory from the heap
*
*Purpose:
* Allocate of block of memory of at least size bytes from the heap and
* return a pointer to it.
*
* Calls the new appropriate new handler (if installed).
*
*Entry:
* size_t size - size of block requested
*
*Exit:
* Success: Pointer to memory block
* Failure: NULL (or some error value)
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/
void * __cdecl _malloc_base(
size_t size
)
#ifndef _POSIX_
{
return _nh_malloc_base( size, _newmode ) ;
}
/***
*void *_nh_malloc_base(size_t size) - Get a block of memory from the heap
*
*Purpose:
* Allocate of block of memory of at least size bytes from the heap and
* return a pointer to it.
*
* Calls the appropriate new handler (if installed).
*
* There are two distinct new handler schemes supported. The 'new' ANSI
* C++ scheme overrides the 'old' scheme when it is activated. A value of
* _NOPTH for the 'new' handler indicates that it is inactivated and the
* 'old' handler is then called.
*
*Entry:
* size_t size - size of block requested
*
*Exit:
* Success: Pointer to memory block
* Failure: NULL (or some error value)
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/
void * __cdecl _nh_malloc_base(
size_t size,
int nhFlag
)
{
void * retp;
/* validate size */
if ( size > _HEAP_MAXREQ )
return NULL;
#ifdef WINHEAP
/* size == 0 bumped up to 1 */
size = (size ? size : 1);
#else
/* round requested size */
size = _ROUND2(size, _GRANULARITY);
#endif /* WINHEAP */
for (;;) {
/* allocate memory block */
retp = _heap_alloc_base( size );
/*
* if successful allocation, return pointer to memory
* if new handling turned off altogether, return NULL
*/
if (retp || nhFlag == 0)
return retp;
/* call installed new handler */
if (!_callnewh(size))
return NULL;
/* new handler was successful -- try to allocate again */
}
}
/***
*void *_heap_alloc_base(size_t size) - does actual allocation
*
*Purpose:
* Same as malloc() except the new handler is not called.
*
*Entry:
* See malloc
*
*Exit:
* See malloc
*
*Exceptions:
*
*******************************************************************************/
void * __cdecl _heap_alloc_base (
size_t size
)
#endif /* _POSIX_ */
{
#ifndef WINHEAP
_PBLKDESC pdesc;
_PBLKDESC pdesc2;
#endif
#ifdef HEAPHOOK
/* call heap hook if installed */
if (_heaphook) {
void * retp;
if ((*_heaphook)(_HEAP_MALLOC, size, NULL, (void *)&retp))
return retp;
}
#endif /* HEAPHOOK */
#ifdef WINHEAP
return HeapAlloc( _crtheap, 0, size );
}
#else /* WINHEAP */
/* try to find a big enough free block
*/
if ( (pdesc = _heap_search(size)) == NULL )
{
if ( _heap_grow(size) != -1 )
{
/* try finding a big enough free block again. the
* success of the call to _heap_grow should guarantee
* it, but...
*/
if ( (pdesc = _heap_search(size)) == NULL )
{
/* something unexpected, and very bad, has
* happened. abort!
*/
_heap_abort();
}
}
else
return NULL;
}
/* carve the block into two pieces (if necessary). the first piece
* shall be of the exact requested size, marked inuse and returned to
* the caller. the leftover piece is to be marked free.
*/
if ( _BLKSIZE(pdesc) != size ) {
/* split up the block and free the leftover piece back to
* the heap
*/
if ( (pdesc2 = _heap_split_block(pdesc, size)) != NULL )
_SET_FREE(pdesc2);
}
/* mark pdesc inuse
*/
_SET_INUSE(pdesc);
/* check proverdesc and reset, if necessary
*/
_heap_desc.proverdesc = pdesc->pnextdesc;
return( (void *)((char *)_ADDRESS(pdesc) + _HDRSIZE) );
}
/***
*_PBLKDESC _heap_split_block(pdesc, newsize) - split a heap allocation block
* into two allocation blocks
*
*Purpose:
* Split the allocation block described by pdesc into two blocks, the
* first one being of newsize bytes.
*
* Notes: It is caller's responsibilty to set the status (i.e., free
* or inuse) of the two new blocks, and to check and reset proverdesc
* if necessary. See Exceptions (below) for additional requirements.
*
*Entry:
* _PBLKDESC pdesc - pointer to the allocation block descriptor
* size_t newsize - size for the first of the two sub-blocks (i.e.,
* (i.e., newsize == _BLKSIZE(pdesc), on exit)
*
*Exit:
* If successful, return a pointer to the descriptor for the leftover
* block.
* Otherwise, return NULL.
*
*Exceptions:
* It is assumed pdesc points to a valid allocation block descriptor and
* newsize is a valid heap block size as is (i.e., WITHOUT rounding). If
* either of these of assumption is violated, _heap_split_block() will
* likely corrupt the heap. Note also that _heap_split_block will simply
* return to the caller if newsize >= _BLKSIZE(pdesc), on entry.
*
*******************************************************************************/
_PBLKDESC __cdecl _heap_split_block (
REG1 _PBLKDESC pdesc,
size_t newsize
)
{
REG2 _PBLKDESC pdesc2;
_ASSERTE(("_heap_split_block: bad pdesc arg", _CHECK_PDESC(pdesc)));
_ASSERTE(("_heap_split_block: bad newsize arg", _ROUND2(newsize,_GRANULARITY) == newsize));
/* carve the block into two pieces (if possible). the first piece
* is to be exactly newsize bytes.
*/
if ( (_BLKSIZE(pdesc) > newsize) && ((pdesc2 = __getempty())
!= NULL) )
{
/* set it up to manage the second piece and link it in to
* the list
*/
pdesc2->pblock = (void *)((char *)_ADDRESS(pdesc) + newsize +
_HDRSIZE);
*(void **)(pdesc2->pblock) = pdesc2;
pdesc2->pnextdesc = pdesc->pnextdesc;
pdesc->pnextdesc = pdesc2;
return pdesc2;
}
return NULL;
}
#endif /* WINHEAP */