Re: [ROOT] [roottalk] TMatrixF/D::Clear()

From: Fons Rademakers (Fons.Rademakers@cern.ch)
Date: Tue Mar 30 2004 - 04:05:54 MEST 

Hi Matevz,

  this bug has been fixed now in the cvs version.

Cheers, Fons.



On Mon, 2004-03-29 at 13:01, Matevz Tadel wrote:
> Hi,
> 
> The following sequence causes segv with 4.00/03:
> 
> root [0] TMatrixF m(2,2)
> root [1] TBuffer b(TBuffer::kWrite)
> root [2] m.Streamer(b)
> root [3] b.SetReadMode()
> root [4] b.SetBufferOffset(0)
> root [5] TMatrixF n(2,2)      // If default ctor is used it works fine.
> root [6] n.Streamer(b)
> 
>   *** Break *** segmentation violation
> 
> I traced it down to a leftover from the TMatrixF/D::Clear() method, 
> which is also called from the Streamer(). By adding 'fElements = 0;' to 
> Clear(), everything is fine. A patch with the above fix is attached.
> 
> I'm not exactly sure in what ways the Clear() method is used ... perhaps 
> a more elaborate fix is needed.
> 
> Cheers,
> Matevz
> 
> ______________________________________________________________________
> 
> Common subdirectories: root.403.src.orig/matrix/inc/CVS and root.403.src/matrix/inc/CVS
> diff -u root.403.src.orig/matrix/inc/TMatrixD.h root.403.src/matrix/inc/TMatrixD.h
> --- root.403.src.orig/matrix/inc/TMatrixD.h	2004-03-21 11:52:27.000000000 +0100
> +++ root.403.src/matrix/inc/TMatrixD.h	2004-03-26 18:34:47.000000000 +0100
> @@ -77,7 +77,11 @@
>    virtual const Double_t *GetMatrixArray  () const;
>    virtual       Double_t *GetMatrixArray  ();
>  
> -  virtual void Clear(Option_t * /*option*/ ="") { if (fIsOwner) Delete_m(fNelems,fElements); fNelems = 0; }
> +  virtual void Clear(Option_t * /*option*/ ="") {
> +    if (fIsOwner) Delete_m(fNelems,fElements);
> +    fElements = 0;
> +    fNelems = 0;
> +  }
>  
>    void      Use         (Int_t nrows,Int_t ncols,Double_t *data);
>    void      Use         (Int_t row_lwb,Int_t row_upb,
> diff -u root.403.src.orig/matrix/inc/TMatrixF.h root.403.src/matrix/inc/TMatrixF.h
> --- root.403.src.orig/matrix/inc/TMatrixF.h	2004-03-21 11:52:27.000000000 +0100
> +++ root.403.src/matrix/inc/TMatrixF.h	2004-03-26 18:34:42.000000000 +0100
> @@ -78,7 +78,11 @@
>    virtual const Float_t *GetMatrixArray  () const;
>    virtual       Float_t *GetMatrixArray  ();
>  
> -  virtual void Clear(Option_t * /*option*/ ="") { if (fIsOwner) Delete_m(fNelems,fElements); fNelems = 0; }
> +  virtual void Clear(Option_t * /*option*/ ="") {
> +    if (fIsOwner) Delete_m(fNelems,fElements);
> +    fElements = 0;
> +    fNelems = 0;
> +  }
>  
>    void      Use         (Int_t nrows,Int_t ncols,Float_t *data);
>    void      Use         (Int_t row_lwb,Int_t row_upb,
-- 
Org:    CERN, European Laboratory for Particle Physics.
Mail:   1211 Geneve 23, Switzerland
E-Mail: Fons.Rademakers@cern.ch              Phone: +41 22 7679248
WWW:    http://www.rademakers.org/fons/      Fax:   +41 22 7679480

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