Re: Why getch blocked when I did type something?

[Thomas Dickey]

On Wed, 17 Dec 2008, John Daker wrote:

> Can gdb tell more info ?

it might, depending on what libraries you're using.

none of them have been compiled with debug-information.

> such as where did it hang?
> what is the address "0x420cdb44" stand for?

"read()" is in the C runtime library, for which you have no debug 
information.  So gdb just tells you the address.

> On Wed, Dec 17, 2008 at 7:48 AM, Thomas Dickey <address@hidden> wrote:
> > On Tue, Dec 16, 2008 at 02:42:33PM +0800, John Daker wrote:
> > > Hi,all
> > > I recently had a problem that my program hang while I type something.
> > > First I thought it is blocked in read() from the tty, but it happens
> > > after I use select and set O_NONBLOCK .
> >
> > ncurses might be using select() to do timeouts - but assuming your
> > application's running all in the same thread, that shouldn't be
> > a conflict.
> >
> > > And finally I realize that it is blocked in read() from getch() after
> > > I gdb attach the process:
> > ...
> > > (gdb) bt
> > > #0  0x420cdb44 in read () from /lib/i686/libc.so.6
> > > #1  0x4006cb44 in __JCR_LIST__ () from /lib/i686/libpthread.so.0
> >
> > I do see you're using pthread though.
> >
> > > #2  0x4002db88 in kgetch () from /usr/lib/libncurses.so.5
> > > #3  0x4002d335 in _nc_wgetch () from /usr/lib/libncurses.so.5
> > > #4  0x4002d8b8 in wgetch () from /usr/lib/libncurses.so.5
> > > #5  0x0804ba67 in main (argc=3, argv=0xbffffa54) at sitas.c:754
> > > #6  0x420158d4 in __libc_start_main () from /lib/i686/libc.so.6
> > > (gdb) q
> > >
> > > I do type something but the program hang there, does anybody know why?
> > > Or maybe a bug of ncurses?
> >
> > without a sample program, it's hard to guess.
> >
> > kgetch is trying to fill in the rest of the characters for a match
> > against the function keys, etc.
> >
> > --
> > Thomas E. Dickey <address@hidden>
> > http://invisible-island.net
> > ftp://invisible-island.net
> >
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.4.9 (GNU/Linux)
> >
> > iEYEARECAAYFAklIPl8ACgkQcCNT4PfkjtscQgCgu67QLCwNHaRvVGGePt8LMcyx
> > 9asAnjpDkS6NBb47LuLVCPlcF/FOS3Ff
> > =OTyV
> > -----END PGP SIGNATURE-----

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net