home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Tricks of the Windows Gam…ming Gurus (2nd Edition)
/
Disc2.iso
/
vc98
/
crt
/
src
/
heapwalk.c
< prev
next >
Wrap
C/C++ Source or Header
|
1998-06-17
|
8KB
|
294 lines
/***
*heapwalk.c - walk the heap
*
* Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the _heapwalk() function
*
*******************************************************************************/
#ifdef WINHEAP
#include <cruntime.h>
#include <windows.h>
#include <errno.h>
#include <malloc.h>
#include <mtdll.h>
#include <stddef.h>
#include <stdlib.h>
#include <winheap.h>
/***
*int _heapwalk() - Walk the heap
*
*Purpose:
* Walk the heap returning information on one entry at a time.
*
*Entry:
* struct _heapinfo {
* int * _pentry; heap entry pointer
* size_t size; size of heap entry
* int _useflag; free/inuse flag
* } *entry;
*
*Exit:
* Returns one of the following values:
*
* _HEAPOK - completed okay
* _HEAPEMPTY - heap not initialized
* _HEAPBADPTR - _pentry pointer is bogus
* _HEAPBADBEGIN - can't find initial header info
* _HEAPBADNODE - malformed node somewhere
* _HEAPEND - end of heap successfully reached
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _heapwalk (
struct _heapinfo *_entry
)
{
PROCESS_HEAP_ENTRY Entry;
DWORD errval;
int errflag;
int retval = _HEAPOK;
Entry.wFlags = 0;
Entry.iRegionIndex = 0;
if ( (Entry.lpData = _entry->_pentry) == NULL ) {
if ( !HeapWalk( _crtheap, &Entry ) ) {
if ( GetLastError() == ERROR_CALL_NOT_IMPLEMENTED ) {
_doserrno = ERROR_CALL_NOT_IMPLEMENTED;
errno = ENOSYS;
return _HEAPEND;
}
return _HEAPBADBEGIN;
}
}
else {
if ( _entry->_useflag == _USEDENTRY ) {
if ( !HeapValidate( _crtheap, 0, _entry->_pentry ) )
return _HEAPBADNODE;
Entry.wFlags = PROCESS_HEAP_ENTRY_BUSY;
}
nextBlock:
/*
* Guard the HeapWalk call in case we were passed a bad pointer
* to an allegedly free block.
*/
__try {
errflag = 0;
if ( !HeapWalk( _crtheap, &Entry ) )
errflag = 1;
}
__except( EXCEPTION_EXECUTE_HANDLER ) {
errflag = 2;
}
/*
* Check errflag to see how HeapWalk fared...
*/
if ( errflag == 1 ) {
/*
* HeapWalk returned an error.
*/
if ( (errval = GetLastError()) == ERROR_NO_MORE_ITEMS ) {
return _HEAPEND;
}
else if ( errval == ERROR_CALL_NOT_IMPLEMENTED ) {
_doserrno = errval;
errno = ENOSYS;
return _HEAPEND;
}
return _HEAPBADNODE;
}
else if ( errflag == 2 ) {
/*
* Exception occurred during the HeapWalk!
*/
return _HEAPBADNODE;
}
}
if ( Entry.wFlags & (PROCESS_HEAP_REGION |
PROCESS_HEAP_UNCOMMITTED_RANGE) )
{
goto nextBlock;
}
_entry->_pentry = Entry.lpData;
_entry->_size = Entry.cbData;
if ( Entry.wFlags & PROCESS_HEAP_ENTRY_BUSY ) {
_entry->_useflag = _USEDENTRY;
}
else {
_entry->_useflag = _FREEENTRY;
}
return( retval );
}
#else /* WINHEAP */
#include <cruntime.h>
#include <heap.h>
#include <malloc.h>
#include <mtdll.h>
#include <stddef.h>
/***
*int _heapwalk() - Walk the heap
*
*Purpose:
* Walk the heap returning information on one entry at a time.
*
*Entry:
* struct _heapinfo {
* int * _pentry; heap entry pointer
* size_t size; size of heap entry
* int _useflag; free/inuse flag
* } *entry;
*
*Exit:
* Returns one of the following values:
*
* _HEAPOK - completed okay
* _HEAPEMPTY - heap not initialized
* _HEAPBADPTR - _pentry pointer is bogus
* _HEAPBADBEGIN - can't find initial header info
* _HEAPBADNODE - malformed node somewhere
* _HEAPEND - end of heap successfully reached
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _heapwalk (
struct _heapinfo *_entry
)
{
REG1 _PBLKDESC pdesc;
_PBLKDESC polddesc;
int retval = _HEAPOK;
/*
* Lock the heap
*/
_mlock(_HEAP_LOCK);
/*
* Quick header check
*/
if ( (_heap_desc.pfirstdesc == NULL) ||
(_heap_desc.proverdesc == NULL) ||
(_heap_desc.sentinel.pnextdesc != NULL) ) {
retval = _HEAPBADBEGIN;
goto done;
}
/*
* Check for an empty heap
*/
if ( _heap_desc.pfirstdesc == &_heap_desc.sentinel ) {
retval = _HEAPEMPTY;
goto done;
}
/*
* If _pentry is NULL, return info about the first entry.
* Else, get info about the next entry in the heap.
*/
if ( _entry->_pentry == NULL ) {
pdesc = _heap_desc.pfirstdesc;
}
else {
/*
* Find the entry we gave to the user last time around
*/
if ( _heap_findaddr( (void *)((char *)(_entry->_pentry) -
_HDRSIZE), &polddesc) != _HEAPFIND_EXACT ) {
retval = _HEAPBADPTR;
goto done;
}
pdesc = polddesc->pnextdesc;
} /* else */
/*
* pdesc = entry to return info about
*/
/*
* Skip over dummy entries
*/
while ( _IS_DUMMY(pdesc) )
pdesc = pdesc->pnextdesc;
/*
* See if we're at the end of the heap
*/
if ( pdesc == &_heap_desc.sentinel ) {
retval = _HEAPEND;
goto done;
}
/*
* Check back pointer (note that pdesc cannot point to a dummy
* descriptor since we have skipped over them)
*/
if (!_CHECK_PDESC(pdesc)) {
retval = _HEAPBADPTR;
goto done;
}
/*
* Return info on the next block
*/
_entry->_pentry = ( (void *)((char *)_ADDRESS(pdesc) + _HDRSIZE) );
_entry->_size = _BLKSIZE(pdesc);
_entry->_useflag = ( _IS_INUSE(pdesc) ? _USEDENTRY : _FREEENTRY );
/*
* Common return
*/
done:
/*
* Release the heap lock
*/
_munlock(_HEAP_LOCK);
return(retval);
}
#endif /* WINHEAP */