MantisBT - KWWidgets
View Issue Details
IDProjectCategoryView StatusDate SubmittedLast Update
0007141KWWidgetspublic2008-06-02 16:432008-06-03 09:29
Reporterkentwilliams 
Assigned ToYumin Yuan 
PrioritynormalSeverityminorReproducibilityalways
StatusresolvedResolutionfixed 
PlatformOSOS Version
Summary0007141: vtkKWLoadSaveDialog initially lists '1' as the file type in the 'Files of type:' combo box.
DescriptionvtkKWLoadSaveDialog initially lists '1' as the file type in the 'Files of type:' combo box.
Steps To Reproduce
Additional InformationI tracked this down and provide a patch.

The problem is this: first, a call to vtkKWComboBox::GetValueFromIndex() is made. This calls this->Script to get the value out of the TK widget.

Then a call is made to vtkKWComboBox::SetValue(), which calls vtkKWWidget::IsAlive(), which calls vtkKWWidget::IsAlive(), which calls vtkKWApplication::EvaluateBooleanExpression() which calls vtkKWTkUtilities::EvaluateString() to get the value.

But ... deep breath ... EvaluateString is the same function that vtkKWComboBox::GetValueFromIndex() calls to get the Nth string from the Combo box widget. And EvaluateString returns a static char * value that is overwritten every time it is called.

The solution is to save the string returned from GetValueFromIndex, before calling SetValue.
TagsNo tags attached.
Relationships
Attached Filespatch vtkKWFileBrowserDialog.cxx.patch (1,175) 2008-06-02 16:43
https://public.kitware.com/Bug/file/1512/vtkKWFileBrowserDialog.cxx.patch
Issue History
Date ModifiedUsernameFieldChange
2008-06-02 16:43kentwilliamsNew Issue
2008-06-02 16:43kentwilliamsFile Added: vtkKWFileBrowserDialog.cxx.patch
2008-06-03 08:51Sebastien BarreStatusnew => assigned
2008-06-03 08:51Sebastien BarreAssigned To => Yumin Yuan
2008-06-03 09:24Yumin YuanNote Added: 0012210
2008-06-03 09:28Yumin YuanNote Added: 0012211
2008-06-03 09:29Yumin YuanStatusassigned => resolved
2008-06-03 09:29Yumin YuanResolutionopen => fixed

Notes
(0012210)
Yumin Yuan   
2008-06-03 09:24   
CVS commit
BUG: Try the fix again. (silly me for last reverse). The returned
value (const char*) from vtkKWComboBox::GetValueFromIndex() is only
pointing to a temporary buffer, and it should be copied locally for
later use.

FYI, Patrick Emond reported this problem a couple weeks ago, and I
committed a fix, but later I reversed that fix because the File
Browser was broken due to other changes in vtksys, and I never put
that fix back in after figuring out why the file browser was broken.


On Mon, Jun 2, 2008 at 4:58 PM, kent williams <nkwmailinglists@gmail.com> wrote:
> I logged this in Mantis -- http://www.itk.org/Bug/view.php?id=7141 [^] --
> I provide a patch for this specific problem, but I worry that there
> are other potential issues elsewhere in KWWidgets.

> ...

There are some other methods in KWW classes, just like
vtkKWComboBox::GetValueFromIndex() , the returned value is a pointer
to a temporary buffer, which should be copied *immediately* to your
own storage. If you grep *temporary buffer* in KWW header files, you
will see most (if not all) of these methods.
Apparently, the doc (comments) for vtkKWComboBox::GetValueFromIndex()
did not say that :-(, and I added comments to show this *feature*.
(0012211)
Yumin Yuan   
2008-06-03 09:28   
More comments from Sebastien:


On Tue, Jun 3, 2008 at 8:56 AM, Sebastien BARRE <sebastien.barre@kitware.com> wrote:
> At 6/2/2008 10:58 PM, kent williams wrote:
>
>> What the bug comes down to is this: If you make any of the myriad
>> calls that end up using ad-hoc TCL scripts to pull values out of TK
>> widgets, you have to save the result before any calling any other
>> method that ends up using a TCL script.
>
> Yes, it's a well known issue, and we have tried to document it for every
> method that returns a pointer to that specific buffer (i.e. it mostly
> concerns methods returning char*). If it bites you in a specific class, let
> us know and we will add more documentation.
>