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My python programs using curses library do not work
with version 2.4.3.Even the 'ncurses.py ' demo program
in the Demo/curses directory does not work correctly.
The problem seems to be in the 'panels' library

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What do you mean by "do not work"? What operating system and
what curses implementation are you using?

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Sorry my original post was incomplete. I am running
slackware 10.2 (linux kernel 2.6).The python library was
tested with ncurses 5.4 and ncurses 5.5( the latest
release). All programs run OK with 2.4.1.As I said ,the 
curses demo that comes with the Python distributions runs OK
with 2.4.1 but 
not with 2.4.3 - I have both on my machine

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I confirm the problem. Every program using curses library
segfaults and there's only one error before it happens:
...
import curses # directory /usr/share/python2.4/curses
import curses # precompiled from
/usr/share/python2.4/curses/__init__.pyc
dlopen("/usr/lib/python2.4/lib-dynload/_curses.so", 2);
import _curses # dynamically loaded from
/usr/lib/python2.4/lib-dynload/_curses.so
import curses.wrapper # precompiled from
/usr/share/python2.4/curses/wrapper.pyc
import curses.panel # precompiled from
/usr/share/python2.4/curses/panel.pyc
dlopen("/usr/lib/python2.4/lib-dynload/_curses_panel.so", 2);
import _curses_panel # dynamically loaded from
/usr/lib/python2.4/lib-dynload/_curses_panel.so
Traceback (most recent call last):
 File "ncurses.py", line 273, in ?
 curses.wrapper(demo_panels)
 File "/usr/share/python2.4/curses/wrapper.py", line 49, in
wrapper
_curses.error: nocbreak() returned ERR
I'm running Linux (PLD) with Python 2.4.3 and ncurses 5.5.
With Python 2.4.2 everything worked fine.

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I can't reproduce any of this on Debian;
Demo/curses/ncurses.py runs fine. Can you please
1. run ldd on _curses.so, and report the output, and
2. edit setup.py, removing the lines that deal with ncursesw,
3. atler_: produce a gdb backtrace on the time of the crash,
4: vnainar: please report what you mean by "does not work".
Does it erase your hard disk? turn off the machine? Paint
things blue instead of red?

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Cannot reproduce on Gentoo. All the files in the Demo/curses
directory run fine.

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$ ldd /usr/lib/python2.4/lib-dynload/_curses.so
 libncursesw.so.5 => /usr/lib/libncursesw.so.5
(0x7004c000)
 libpthread.so.0 => /lib/libpthread.so.0 (0x70080000)
 libc.so.6 => /lib/libc.so.6 (0x700e4000)
 libdl.so.2 => /lib/libdl.so.2 (0x70228000)
 libtinfow.so.5 => /usr/lib/libtinfow.so.5 (0x7023c000)
 /lib/ld-linux.so.2 (0x70000000)
...
Program received signal SIGSEGV, Segmentation fault.
0x7063947c in hide_panel () from /usr/lib/libpanel.so.5
gdb) bt
#0 0x7063947c in hide_panel () from /usr/lib/libpanel.so.5
#1 0x706254b8 in ?? () from
/usr/lib/python2.4/lib-dynload/_curses_panel.so
#2 0x706254b8 in ?? () from
/usr/lib/python2.4/lib-dynload/_curses_panel.so
Previous frame identical to this frame (corrupt stack?)
It seems that only programs using panel library cause
segfaults (all other demos run fine except ncurses.py),
sorry for a mistake in a last post.
loewis: I'm not sure I understand second point. What excatly
should be changed in setup.py?

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The buildbot boxes don't show this problem.
You might need to rebuild a Python with -g and unstripped to
get a useful backtrace.

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More complete backtrace, I hope it will help:
http://pastebin.com/649445 

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atler_: around line 427, you find
 if self.compiler.find_library_file(lib_dirs,
 'ncursesw'):
 readline_libs.append('ncursesw')
 elif self.compiler.find_library_file(lib_dirs,
 'ncurses'):
Replace that with
 if self.compiler.find_library_file(lib_dirs,
 'ncurses'):
(i.e. dropping the ncursesw part), and rebuild.

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loewis: removing lines refering to ncursesw solves the
problem. ncurses.py runs fine as well as other programs.
What is actual problem then? Something with ncursesw or
with python?
Anyway, Thanks for your help.

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That's hard to tell. Somebody would have to debug ncurses to
find out why it crashes. Notice that it crashes only on some
installations, so it is likely rather a problem with your
ncurses installation, than with Python (or even with ncurses
itself).

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Removing 'ncursesw' (there are two references to it in
'setup.py') seems to solve the problem. I noticed one more
oddity. Even before the above recompilation , it ran fine
on an Xterm !

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Ah, ok. vnainar, atler_: What terminal had you been using to
make it crash? What is your locale? Any other conditions
that might be relevant (e.g. dimension of the terminal)?

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Well , it is the linux console (in VGA mode ).
The local is en_US.The size of the console is
100X37.

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I couldn't reproduce the problem on a Linux console
(although my console had a different size); so it remains
unreproducable for me.

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Half day of debugging and it seems that I found an answer...
just by accident ;).
When curses module is linked against ncursesw it seems that
it also should be linked against panelw not plain panel.
After changing this in setup.py, ncurses.py demo finally
runs fine.

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Good spotting! Can everybody please confirm that the
attached patch fixes the problem?

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/me confirms

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I have a similar problem on OS/2. When running any script
that uses curses I get:
[U:\dev\Python-2.4.3\PC\os2emx]python test_curses.py
Traceback (most recent call last):
 File "test_curses.py", line 242, in ?
 curses.wrapper(main)
 File "U:/DEV/PYTHON-2.4.3/Lib/curses/wrapper.py", line 49,
in wrapper
 curses.nocbreak()
_curses.error: nocbreak() returned ERR
If I remove the reference to nocbreak() from wrapper.py, I
get the same error but in endwin(), removing endwin() from
wrapper.py, I get an error in cbreak(), removing cbreak()
then some scripts work.
For example, from the demo folder, all work exceptlife.py &
xmas.py, which both return an error "_curses.error:
nocbreak() returned ERR" on various line numbers.
Seems certain curses functions are working correctly, others
aren't.
The patch in this bug does NOT make any difference here.

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Andrew, could you apply this after the freeze is over?

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Sure. 

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Committed to the trunk in rev. 51134.

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Committed to 2.4 branch in rev.51136.