Beware of Memory Leak from abusing undocumented With...EndWith syntax on DllStructs

[AutoXenon]

If a function returns a struct member while inside a With statement, the struct gets a new instance that do not get cleaned up.

 

HotKeySet('{esc}',quit)
GUICreate("")
GUISetState()
Local $text
While 1
    $text = state()
    Sleep(10) ; don't remove this, or your RAM will blow up instantly
WEnd

Func state()
     Local Static $struct = DllStructCreate('wchar string[1024]')
     With $struct
          Return .string
     EndWith
EndFunc

Func quit()
     exit
EndFunc

 

 

Tested on 3.3.16.0

Edited November 5, 2022 by AutoXenon

[pixelsearch]

Hi AutoXenon

Could it be because the expression you used in your script isn't an object type expression ?

Your script :

With $struct
    ...

ConsoleWrite(VarGetType($struct) & @crlf)
DLLStruct

AutoIt help file, topic With...EndWith

Parameters
expression    Must be an object type expression

Help file example :

With $oExcel.activesheet
    ...

ConsoleWrite(VarGetType($oExcel.activesheet) & @crlf)
Object

 

[AutoXenon]

Yes, hence my thread title. It's not meant to be used on DllStructs, so I'm aware of the perils of treading on undocumented grounds. This topic is meant to point out specific instances of where such unintended usage might go wrong.

[jchd]

This is a defect in autoit3.exe and you should open a ticket about it.

autoit3.exe correctly barks when With is used on, e.g. a string while it doesn't for DllStruct.

Local $m[]
Local $b[3]
Local $a = [ _
    DllStructCreate('wchar string[1024]'), _
 _  ;   $m, _
 _  ;   $b, _
 _  ;   123, _
 _  ;   "abc", _
 _  ;   Binary(123), _
 _  ;   Ptr(123456), _
 _  ;   True, _
 _  ;   Null _
    ObjCreate("shell.application") _
]
For $v In $a
    ConsoleWrite(VarGetType($v) & @TAB)
    With $v
        ConsoleWrite("passed" & @LF)
    EndWith
Next

Uncomment the various datatypes to check by yourself.

[jchd]

Created ticket #3925

[SkysLastChance]

Sleep(10) ; don't remove this, or your RAM will blow up instantly

Is this true?