RE: [Devel] potential of memory leaking in kern

[Turner David]

Hello,

> -----Original Message-----
> From: address@hidden [mailto:address@hidden
> Behalf Of Masatake YAMATO
> Sent: Wednesday, November 12, 2003 1:09 PM
> To: address@hidden
> Subject: [Devel] potential of memory leaking in kern
> 
> 
> Hi,
> 
> In tt_face_load_kern, the results of FT_NEW_ARRAY and FT_FRAME_ENTER
> are checkd in single if-condition. If FT_NEW_ARRAY is successful but
> FT_FRAME_ENTER is failed, the buffer allocated by FT_NEW_ARRAY will
> be never freed.
> 

That's not true, it will be freed when the face will be closed, i.e.
most likely when FT_Done_Face will be called. This technique is used
very widely in the engine, it consists of:

  - using object destructors as the _only_ location where object fields
    are released

  - initializing / loading functions shall report errors as soon as
    possible, but shouldn't perform object field cleanup

  - however, some cleanup may be needed for temporary data allocated
    within an operation that isn't stored directly as an object field
    (e.g. temporary buffers)

Your patch fixes the following issue though:

  - in case of a font file with a broken kerning table, the engine
    _may_ allocate more memory than strictly needed in a FT_Face object

Thanks for your report,

- David Turner
- The FreeType Project  (www.freetype.org)


> Masatake YAMATO
> 
> 2003-11-12  Masatake YAMATO  <address@hidden>
> 
>       * src/sfnt/ttload.c (tt_face_load_kern): 
>       Before jumping to Exit, free face->kern_pairs if 
>       FT_FRAME_ENTER is failed.
> 
> Index: src/sfnt/ttload.c
> ===================================================================
> RCS file: /cvsroot/freetype2/src/sfnt/ttload.c,v
> retrieving revision 1.102
> diff -u -r1.102 ttload.c
> --- ttload.c  2003/06/30 13:08:58     1.102
> +++ ttload.c  2003/11/12 12:04:43
> @@ -1674,9 +1674,13 @@
>          FT_FRAME_EXIT();
>  
>          /* allocate array of kerning pairs */
> -        if ( FT_NEW_ARRAY( face->kern_pairs, num_pairs ) ||
> -             FT_FRAME_ENTER( 6L * num_pairs )            )
> -          goto Exit;
> +        if ( FT_NEW_ARRAY( face->kern_pairs, num_pairs ) )
> +       goto Exit;
> +     if ( FT_FRAME_ENTER( 6L * num_pairs )            )
> +       {
> +         FT_FREE( face->kern_pairs );
> +         goto Exit;
> +       }
>  
>          pair  = face->kern_pairs;
>          limit = pair + num_pairs;
> 
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> 

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