Re: newterm() returning NULL on serial console

[Thomas Dickey]

On Tue, Nov 07, 2006 at 03:54:52AM -0500, Katarina Machalkova wrote:
> Hi there!
> 
> I have the following code snippet:
> 
> char * mytty = ttyname( 0 );
>     if ( mytty ) {
>       FILE * fdi = fopen( mytty, "r" );
>       if (!fdi) {
>          UIERR << "fdi: (" << errno << ") " << strerror(errno) << endl;
>       }
>       FILE * fdo = fopen( mytty, "w" );
>       if (!fdo) {
>          UIERR << "fdo: (" << errno << ") " << strerror(errno) << endl;
>       }
>       if ( fdi && fdo ) {
>         theTerm = newterm( 0, fdo, fdi );
>         if ( theTerm == NULL )
>           throw NCursesError( "newterm() failed" );
> ....    
>  
> The problem is, that once 'console=ttyS0' parameter is passed to the kernel 
> at 
> boot (this is SUSE Linux Enterprise Server 10), newterm() function in this 
> code keeps returning NULL pointer. 
> 
> What happens here is that:
> * ttyname() correctly returns '/dev/console' string
> * fopen() call succesfully opens /dev/console for reading and for writing 
> (i.e. returns non-NULL pointers)
> * yet newterm() returns NULL once serial console is used, no matter what TERM 
> environment variable is used. Without serial console, all works fine
> 
> Any clue what might be going wrong in newterm() function ? Or what else 
> should 
> I check and who might be the possible culprit ? 

I can only guess too.  newterm can return a null for three different cases
(reading the code):

        a) setupterm fails (usually because it cannot obtain the terminfo)

        b) the apparent screensize is very large (so it cannot allocate memory)

        c) possibly some problem setting terminal modes.

> Unfortunately, the machine on which the error can be reproduced is somewhere 
> at the customer's site and I have neither physical nor network access to 
> it  :-( and I cannot easily debug it
> Yet I would be grateful for any ideas or suggestions ...
> Thanks

I'd suggest making a static executable built against the tracing version
of ncurses (so you don't have to redeliver libraries to get the test),
get the customer to run that, e.g., with NCURSES_TRACING=0xffff,
and looking to see whether I can see the failure in the "trace" file.

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

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