216 lines
5.4 KiB
C++
216 lines
5.4 KiB
C++
//+-------------------------------------------------------------------------
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//
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// Copyright (C) 1992, Microsoft Corporation.
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//
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// File: SysMem.CXX
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//
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// Contents: System Memory Management routines
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//
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// Functions: MemAlloc, MemFree, MemAllocLinked
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//
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// History: 10-Feb-92 AlexT Created
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// 07-May-92 MikeSe Converted to using Win32 Heap functions.
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// 14-Jul-92 randyd Added MemSwitchRoot, see memmgmt.doc.
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// 5-Oct-93 isaache Slight reorganization, conversion to 'new'
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// 13-Jul-94 doncl stole from ole32, put in ADs proj, deleted
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// MemSwitchRoot, switched to naked
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// Win32 CRITICAL_SECTION usage
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//
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// Notes: For additional information, see win4adm\standrds\memmgmt.doc.
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//
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// This memory management package is multithread capable - the
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// only place it makes a difference is in MemAllocLinked and
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// MemSwitchRoot, where we use a critical section t
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// protect adding link blocks to the list. We rely on the fact
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// that LocalAlloc is multi-thread safe.
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//
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//--------------------------------------------------------------------------
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#include "dswarn.h"
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#include <ADs.hxx>
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#if 0
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#include <excpt.h>
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#include <except.hxx>
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#include <dllsem.hxx>
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#endif
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CRITICAL_SECTION g_csMem;
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// Memory block prefix (for signature and link)
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typedef struct _smheader
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{
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unsigned long ulSignature;
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struct _smheader *psmNext;
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} SMHEADER, *PSMHEADER;
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// Memory block signatures (for strict checks)
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const ULONG ROOT_BLOCK = 0x726f6f74; // 'root'
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const ULONG LINKED_BLOCK = 0x6c696e6b; // 'link'
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static BOOL
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VerifySignature(PSMHEADER psm, ULONG ulSig )
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{
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BOOL fReturn;
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__try
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{
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fReturn = (ulSig == psm->ulSignature );
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}
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__except ( EXCEPTION_EXECUTE_HANDLER )
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{
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fReturn = FALSE;
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}
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return fReturn;
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}
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// This module acts as the declarer of debug support symbols for COMMNOT
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DECLARE_INFOLEVEL(Cn);
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//+-------------------------------------------------------------------------
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//
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// Function: MemAlloc
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//
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// Synopsis: allocates memory block
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//
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// Arguments: [ulSize] -- size of block in bytes
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// [ppv] -- output pointer
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//
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// Returns: status code
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//
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// Algorithm: call new, adding space for header
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//
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// History: 10-Feb-92 AlexT Created
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//
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//--------------------------------------------------------------------------
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HRESULT
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MemAlloc ( unsigned long ulSize, void ** ppv )
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{
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PSMHEADER psm;
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*ppv = NULL;
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psm = (PSMHEADER) LocalAlloc(LMEM_FIXED, ulSize + sizeof(SMHEADER));
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if ( psm != NULL )
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{
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psm->ulSignature = ROOT_BLOCK;
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psm->psmNext = NULL;
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*ppv = psm + 1;
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return S_OK;
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}
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return E_OUTOFMEMORY;
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}
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//+-------------------------------------------------------------------------
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//
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// Function: MemFree
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//
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// Synopsis: release system memory block
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//
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// Arguments: [pvBlockToFree] -- memory block to release
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//
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// Algorithm: Walk list of linked blocks, deleting each one
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//
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// History: 10-Feb-92 AlexT Created
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//
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//--------------------------------------------------------------------------
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HRESULT
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MemFree( void *pvBlockToFree )
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{
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PSMHEADER psm = ((PSMHEADER) pvBlockToFree) - 1;
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if( pvBlockToFree == NULL || psm == NULL )
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return S_OK;
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if( !VerifySignature( psm, ROOT_BLOCK ) )
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{
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Win4Assert( !"MemFree -- not a root block!\n" );
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return MEM_E_INVALID_ROOT;
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}
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do {
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PSMHEADER psmNext = psm->psmNext;
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psm->ulSignature = 0;
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LocalFree(psm);
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psm = psmNext;
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if( psm && !VerifySignature( psm, LINKED_BLOCK ) )
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{
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Win4Assert( !"MemFree -- invalid linked block!\n" );
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return MEM_E_INVALID_LINK;
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}
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} while( psm != NULL );
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return S_OK;
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}
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//+-------------------------------------------------------------------------
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//
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// Function: MemAllocLinked
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//
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// Synopsis: allocates linked memory block
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//
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//
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// Arguments: [pvRootBlock] -- root memory block
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// [ulSize] -- size of new memory block
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// [ppv] -- output pointer
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//
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// Returns: status code
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//
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//
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// History: 10-Feb-92 AlexT Created
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//
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// Notes: pvRootBlock can specify either a root block, or another
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// linked block.
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//
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//--------------------------------------------------------------------------
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HRESULT
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MemAllocLinked ( void *pvRootBlock, unsigned long ulSize, void ** ppv )
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{
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PSMHEADER psm = NULL;
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PSMHEADER psmRoot = ((PSMHEADER) pvRootBlock) - 1;
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*ppv = NULL;
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if ( pvRootBlock == NULL || psmRoot == NULL )
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{
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Win4Assert( !"MemAllocLinked - null root block\n" );
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return MEM_E_INVALID_ROOT;
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}
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if ( !VerifySignature(psmRoot, ROOT_BLOCK)
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&& !VerifySignature(psmRoot,LINKED_BLOCK) )
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{
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Win4Assert( !"MemAllocLinked - invalid root block\n" );
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return MEM_E_INVALID_ROOT;
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}
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psm = (PSMHEADER) LocalAlloc(LMEM_FIXED, ulSize + sizeof(SMHEADER));
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if ( psm == NULL )
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return E_OUTOFMEMORY;
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psm->ulSignature = LINKED_BLOCK;
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EnterCriticalSection(&g_csMem);
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psm->psmNext = psmRoot->psmNext;
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psmRoot->psmNext = psm;
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LeaveCriticalSection(&g_csMem);
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// move psm past header
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*ppv = psm+1;
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return S_OK;
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}
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