Hi Przemek,
I think there is such an unsafe usage of hb_itemGetCPtr()
in philes.c / FREAD().
That one sprang to my mind, but maybe there are more.
Brgds,
Viktor
On 2008.01.11., at 18:01, Przemyslaw Czerpak wrote:
2008-01-11 18:01 UTC+0100 Przemyslaw Czerpak (druzus/at/priv.onet.pl)
* harbour/include/hbapiitm.h
* harbour/source/vm/itemapi.c
+ added new functions:
BOOL hb_itemParamStore( USHORT uiParam, PHB_ITEM pItem )
BOOL hb_itemParamStoreForward( USHORT uiParam, PHB_ITEM
pItem )
They copy/move pItem body to parameter passed by reference and
return TRUE when operation was done successfully (uiParam was
passed
by reference)
+ added new functions for string manipulation:
char * hb_itemLockReadCPtr( PHB_ITEM pItem, ULONG * pulLen );
char * hb_itemLockWriteCPtr( PHB_ITEM pItem, ULONG * pulLen );
void hb_itemUnLockCPtr( char * pszString );
It's recommended to use them instead of hb_itemGetCPtr().
Pointer to string buffer returned by hb_itemLockReadCPtr() will
be always valid even if source item will be cleared, destroyed or
overwritten until hb_itemUnLockCPtr() is called. Each locked
string
has to be unlocked to avoid memory leaks. After unlocking the
string
pointer cannot be longer used.
hb_itemLockWriteCPtr() works like hb_itemLockReadCPtr() but
string
pointer returned by this function is writable so user can change
the body of string item. It's the _ONLY_ one way when it's
possible.
Modifying string items using pointers returned by hb_parc() or
hb_itemGetCPtr() or extracted directly from HB_ITEM body is
_FORBIDDEN_
and can cause unpredictable results (GPF when constant/readonly
memory
pages are changed, changing many different items which share
the same
memory buffer, etc.).
This is code illustrates how to use hb_itemLockReadCPtr()/
hb_itemUnLockCPtr() and it's also good example why
hb_itemGetCPtr()
is very danger function and cannot be used in such case - if you
replace hb_itemLockReadCPtr() with hb_itemGetCPtr() and remove
hb_itemUnLockCPtr() then you will have buggy code.
HB_FUNC( MYFUNC )
{
PHB_ITEM pObject = hb_param( 1, HB_IT_OBJECT )
if( pObject )
{
char * pszName1, * pszName2;
PHB_ITEM pResult;
pResult = hb_objSendMsg( pObject, "POP", 0 );
pszName1 = hb_itemLockReadCPtr( pResult, NULL );
pResult = hb_objSendMsg( pObject, "POP", 0 );
pszName2 = hb_itemLockReadCPtr( pResult, NULL );
if( pszName1 && pszName2 )
hb_retc_buffer( hb_xstrcpy( NULL,
"[", pszName1, "]-[", pszName2, "]",
NULL ) );
hb_itemUnLockCPtr( pszName1 );
hb_itemUnLockCPtr( pszName2 );
}
}
This code shows how to use hb_itemLockWriteCPtr():
proc main()
local cVal, cVal2
cVal := cVal2 := "ABC"
STRPUT( @cVal2, 2, 42 )
? cVal, cVal2
return
#pragma begindump
#include "hbapiitm.h"
HB_FUNC( STRPUT )
{
PHB_ITEM pString = hb_param( 1, HB_IT_STRING );
ULONG ulAt = hb_parnl( 2 );
if( pString && ulAt && ISNUM( 3 ) )
{
ULONG ulLen;
char * pszValue;
pszValue = hb_itemLockWriteCPtr( pString, &ulLen );
if( pszValue )
{
if( ulAt <= ulLen )
pszValue[ ulAt - 1 ] = ( char ) hb_parni( 3 );
hb_itemUnLockCPtr( pszValue );
}
}
}
#pragma enddump
* harbour/include/hbcompdf.h
* harbour/include/hbexprop.h
* harbour/include/hbexprb.c
* harbour/source/compiler/hbmain.c
* harbour/source/compiler/cmdcheck.c
* harbour/source/compiler/hbusage.c
* removed HB_I18N_SUPPORT macro and enabled I18N code in default
build
best regards
Przemek
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