Re: [hpoj-devel] hpoj cmdline problem

[<pa...@rc...>]

Hi, Carl.

Carl Baltser Pedersen wrote:
> Using the hpo to scan, hpo scan bw, it always ended in a segmentation fault
> which annoyed me.
"hpo scan" is mainly test code and isn't terribly useful for scanning.

> Using gdb, I traced the problem to PMLClose() in  pml.c.
> 
> After the PMLUnregisterTrap(), the traps pointer might be NULL because the
> trap might have been free'd.
> 
> Adding a test after PMLProcess((), no more segmentation faults appears.
> 
> void PMLClose(void)
> {
>   static trap_t *curtrap;
> 
>     /* Unregister all traps */
>   while(traps != NULL)
>   {
>     PMLUnregisterTrap(traps->oid);
>     PMLProcess();
> 
>     if( traps == NULL )    <--- Added
>       break;                    <--- Added.
>     curtrap = traps;
>     traps = traps->next;
>     free(curtrap);
>   }
> 
>   free(rcv_buf);
>   MlcCon_close(connection);
>   delete_MlcCon(connection);
> }

From a quick look of the code I'm not sure this is really the problem.
"traps" is essentially the head pointer in a linked list, and the while
loop stops as soon as it reaches the end of the list.  I couldn't find
any other place where items in the list were freed, but perhaps I missed
something.  But if it works for you, then great.  Am I correct in assuming
that this problem only shows up for you when running "hpo scan"?  In that
case I don't think I will worry about it, because I am in the process of
replacing ojlib with PTAL, once I finish adding PML support to PTAL.

> Now is the problem to figure out how to use the scanned data.
> The 590 is not supported by the current SANE interface(ptal-connect) as far
> as I can figure out.
For now that's true, but I plan to fix that eventually.  Lately I've been
concentrating on lower-level I/O issues, which I think will need to be
resolved before scanning will work reliably on this class of OfficeJets
anyway.

> Haven't tried the printing yet as one of the std. HP deskjet drivers
> usually works.
For now that may be your best bet, but keep an eye out for updates of this
project.

David