[Tcl-bugs] [ tktoolkit-Bugs-872299 ] Access violation in tkBTreeFindPixelLine

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Bugs item #872299, was opened at 2004-01-07 12:26
Message generated for change (Comment added) made by traum
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=112997&aid=872299&group_id=12997

Category: 18. [text]
Group: develop: 8.5a0
Status: Open
Resolution: None
Priority: 5
Submitted By: Uwe Traum (traum)
Assigned to: Vince Darley (vincentdarley)
Summary: Access violation in tkBTreeFindPixelLine

Initial Comment:
I got an access violation in tkTextBTree.c Line 1013
tkBTreeFindPixelLine
(nodePtr == NULL)

after playing around in the debugger I recognized that

nodePtr->numPixels == 0.

so 'pixelsLef't is not decremented

this code is called quit often until it crashes. But
never nodePtr->numPixels was 0.

The application is quit complex - so I did not know what
tcl-code is actually called at this time.

Here is the call-stack:

TkBTreeFindPixelLine(TkTextBTree_ * 0x0c69ad48, int 0,
int * 0x04252c80) line 1013 + 23 bytes
TkTextMakePixelIndex(TkText * 0x0c69a8c0, int 0,
TkTextIndex * 0x04252cac) line 323 + 20 bytes
TkTextYviewCmd(TkText * 0x0c69a8c0, Tcl_Interp *
0x04877c70, int 4, Tcl_Obj * const * 0x042530e0) line
5211 + 28 bytes
TextWidgetObjCmd(void * 0x0c69a8c0, Tcl_Interp *
0x04877c70, int 4, Tcl_Obj * const * 0x042530e0) line
1309 + 21 bytes
TclEvalObjvInternal(Tcl_Interp * 0x04877c70, int 4,
Tcl_Obj * const * 0x042530e0, const char * 0x0c5a71d0,
int 57, int 0) line 3143 + 25 bytes
Tcl_EvalEx(Tcl_Interp * 0x04877c70, const char *
0x0c5a71d0, int 57, int 262144) line 3639 + 39 bytes
Tcl_EvalObjEx(Tcl_Interp * 0x04877c70, Tcl_Obj *
0x0c2e9c50, int 262144) line 3872 + 21 bytes
Tcl_EvalObjCmd(void * 0x00000000, Tcl_Interp *
0x04877c70, int 4, Tcl_Obj * const * 0x0487b59c) line
681 + 18 bytes
TclEvalObjvInternal(Tcl_Interp * 0x04877c70, int 4,
Tcl_Obj * const * 0x0487b59c, const char * 0x00000000,
int 0, int 0) line 3143 + 25 bytes
TclExecuteByteCode(Tcl_Interp * 0x04877c70, ByteCode *
0x0c514b40) line 1537 + 27 bytes
TclCompEvalObj(Tcl_Interp * 0x04877c70, Tcl_Obj *
0x053c8b50) line 1005 + 13 bytes
Tcl_EvalObjEx(Tcl_Interp * 0x04877c70, Tcl_Obj *
0x053c8b50, int 0) line 3884 + 13 bytes

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>Comment By: Uwe Traum (traum)
Date: 2004-01-07 14:07

Message:
Logged In: YES 
user_id=770325

Here is a short example to reproduce the error:
(Windows or Solaris)

text .t
pack .t
while {1} {
  puts "insert"
  .t insert end "blabla\n"
  .t yview moveto 1
}

--------

after 12 inserts I got an "segmentation fault"


----------------------------------------------------------------------

Comment By: Vince Darley (vincentdarley)
Date: 2004-01-07 13:02

Message:
Logged In: YES 
user_id=32170

Without a reproducible example in Tcl code, there's very
little chance I'll be able to fix this... So, I think you'll
have to either generate such an example, or debug it further
yourself...

There's nothing obvious wrong with the lines of code in
question.


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