Re: address@hidden: open-network-stream in batch mode causes SIGPOLL under GNU/Linux]

[Andreas Schwab]

"Richard M. Stallman" <address@hidden> writes:

> 3. Execute the following command.
>
>> % emacs -batch -q -no-site-file -l ./foo.el
>
>    Then Emacs exits before the command finishes, and the following
>    error message appears.
>
>> SI/O possible
>
>    The first "S" is the beginning of error message by Emacs, so
>    this is "I/O possible".

The problem is that interrupt_input is always set, but the SIGIO handler
is only installed in !noninteractive mode.  Now make-network-process has
code to call request_sigio after it has finished if interrupt_input is
non-zero, but nobody is handling the SIGIO.

> 4. When you repeat the same command in the same shell process,
>    SIGPOLL will not occur, which seems to be the expected behavior.
>
>> % emacs -batch -q -no-site-file -l ./foo.el
>> Symbol's value as variable is void: foo

I think the reason the SIGIO isn't reported here is that the async
interrupt is still connected to the process group of the previous emacs
instance, which is now defunct, thus there is noone who can receive the
SIGIO.

Probably the best fix is to make (un)request_sigio a no-op in
noninteractive mode.

Andreas.

-- 
Andreas Schwab, SuSE Labs, address@hidden
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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