[Tcl-bugs] [ tcl-Bugs-1276628 ] TCL_CHANNEL_TYPE_4 inconsistent

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Bugs item #1276628, was opened at 2005-08-30 06:46
Message generated for change (Comment added) made by andreas_kupries
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Category: 27. Channel Types
Group: development: 8.5a4
Status: Open
Resolution: None
Priority: 9
Submitted By: Don Porter (dgp)
Assigned to: Andreas Kupries (andreas_kupries)
Summary: TCL_CHANNEL_TYPE_4 inconsistent

Initial Comment:

Releases Tcl 8.4.10 and 8.4.11 included
TCL_CHANNEL_TYPE_4 in the public
header file, defining it to be a 
Tcl_ChannelType struct that includes
and ends with a Tcl_DriverThreadActionProc
field.  (TIP 218)

The HEAD (8.5a4) has added another
field, Tcl_DriverTruncateProc (TIP 208),
but has not created the
TCL_CHANNEL_TYPE_5 to distinguish
channels using that field from those
that do not, and could be used in
an 8.4.11 interp.

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>Comment By: Andreas Kupries (andreas_kupries)
Date: 2006-03-27 09:19

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Looked over the relevant TIPs, i.e. #206/208, and #218.
While both of them talk about going to version 4 for driver
the context makes clear that the version number is
incremented from whatever is maximum at the time the TIP
goes final. #218 says in effect: Right now we known version
0 to 3, and we extend to 4. And from this I conclude that if
version 4 is the actual maximum at time the TIP
implementation is committed it should go to version 5.

I will now change the HEAD to provide version 5, to make the
internal drivers v5 (if they use thread states), etc.


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Comment By: Don Porter (dgp)
Date: 2006-03-09 20:54

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The time to resolve this
report is before 8.5a4
is released.  If valid,
the issue needs fixing,
if invalid, it ought to
be closed.

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Comment By: Andreas Kupries (andreas_kupries)
Date: 2005-10-05 11:04

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Hm.

In the current situation a TYPE_4 channel defining a
truncateProc is perfectly usable in both 8.5. and 8.4. As
8.4 has no Tcl_TruncateChannel API  it will simply never
acess this element. It is no matter that the structure is
actually larger than 8.4 believes it is.

If we go TYPE_5 for the truncateProc the channel would be
unusable in 8.4, because 8.4 is not able to recognize
TYPE_5. Actually it will think that the channel is TYPE_1
and dereference the version number to get the blockmode
proc, crashing the core.





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Comment By: Andreas Kupries (andreas_kupries)
Date: 2005-08-30 11:11

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I dimly remember some discussion about this on tcl-core. It
might have been about a related thing tough. I will have to
dig this out.


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