| Subject: | Curses unusable if GetTerminalSize does not determine screen geometry |
The call to GetTerminalSize can return all zero values for screen
geometry (columns and rows) of a terminal, particularly upon
installation of a Linux distribution with limited termcaps and/or while
using a serial port console. The three calls to GetTerminalSize in
UI.pm should detect this case and prompt the user to type the correct
terminal size. Another option would be to use some reasonable default
values (80x25) then use a Curses window to allow the values to be entered.
As a workaround, I've replaced the calls to GetTerminalSize with
safe_GetTerminalSize() as a subroutine with (in my case) hard-coded
values returned if the values returned by GetTerminalSize are zero.
This is obviously not ideal, but it does solve the issue for me. I
don't know what is the "standard" way (if there is one) to prompt the
user for such details within Curses, since there is no interface as such
yet, thus we can't display widgets, and STDIN seems already intercepted
by the first time this is called.
The basic logic for fixing this problem is simple:
sub safe_GetTerminalSize()
{
my ($cols,$lines) = GetTerminalSize;
if ($cols == 0)
{
#prompt user for $cols
}
if ($lines == 0)
{
#prompt user for $lines
}
return ($cols,$lines);
}
Then just: s/GetTerminalSize/safe_GetTerminalSize/g
(there are only three instances)
Currently, without this patch, if GetTerminalSize returns zero, Curses
will simply "die" with a loop of error messages about the display size
being too small. I actually think this should be a "Critical" bug,
since Curses becomes totally useless, but submitting as "Normal". I
know it is not a very common case that GetTerminalSize will return zero,
but still I think the return should be validated before use and
gracefully prompt the user.
Thank you!