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