flexfax: Re: fix for "Can not open document"

[Hong Kong Observatory <d1swdev@asiaonline.net>]

Hi Matthias,

Please tell how to test your patch then ? Also how to fix the duplicated
document conversion problem (this would waste lots of CPU resource if 
huge document was sent to different destinations) ?

> 
> Hong Kong Observatory wrote:
>     
>     Hi Matthias,
>     
>     I just download Hylafax V4.0pl1 into my IBM PowerPC running AIX 4.2 with
>     gcc 2.7.2 and ghostscript 4.02.
>     
>     I compiled and installed the package without any problem (without your
>     patch). But I cannot reproduce the 'Cannot open document file' problem.
>     
>     I issued the command : sendfax -n -d 1111 -d 2222 doc.ps
>     and made the line 1111 busy. I found that the server did the  conversion
>     ps2fax twice (once for each FAX). Therefore there is no "cannot open
>     document file" problem. But I think this is another problem because
>     the conversion is done once for each destination, this will waste a lot
>     of CPU resource ! Do you think that I have made any mistake in my
>     installation ?
> 
> No. The racing between faxq(1M) and faxsend(1M) (or call it a bug)
> will not show up on each system nor in each situation. With the
> unpatched code of v4.0pl1 it's just a gamble which part wins.
>     
>     Also from the 'syslog' file, I found an error from faxgetty every time
>     before each dispatch :
>     Faxgetty [12345]: ANSWER: Can not lock modem device.
>     but the document was dispatched without errors. Does this imply any
>     potential porblem ?
> 
> No. The faxsend(1M) plays with the modem to send the fax, the modem
> answers with something like "OK" and both (faxsend(1M) and faxgetty(1M))
> can "see" (with poll(2) or select(3C)) that the modem says something
> in response to the AT-cmd (sent down by faxsend(1M)), but because
> the faxsend(1M) has the lock for the device, faxgetty(1M) goes out
> of the way stumbling about it with "Can not lock modem device"
> and waits for the lock to be cleared. That's all.
> 
> 	matthias
> 

K.S.Wat SSA(D)12
Computer Division,
Hong Kong Observatory.