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From: Jeff Sickel <jas@corpus-callosum.com>
In-Reply-To: <0BE4B21D-EDA9-4DF5-8515-7BA27841B3E3@corpus-callosum.com>
Date: Mon, 25 Feb 2013 23:53:09 -0600
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Message-Id: <62A315BD-CDC8-424D-9F5E-EE615F285E39@corpus-callosum.com>
References: <0BE4B21D-EDA9-4DF5-8515-7BA27841B3E3@corpus-callosum.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] APE select() and awkward Python subprocess PIPEfitting
Topicbox-Message-UUID: 1f1f01d0-ead8-11e9-9d60-3106f5b1d025

Actually, that printf was for my debugging:

diff /sys/src/ape/lib/ap/plan9/_buf.c _buf.c
294a295
> /*
298c299
< 				errno =3D EBADF;		/* how X =
tells a client is gone */
---
> 				errno =3D EBADF;		// how X =
tells a client is gone
300a302
> */


On Feb 25, 2013, at 8:29 PM, Jeff Sickel <jas@corpus-callosum.com> =
wrote:

> I've been tracking down little errors in the APE select() function =
that cropped up when trying to use Python's subprocess module.  After a =
few too many hours of investigation, I've come to the conclusion that =
the code that causes error is intentional code to handle a specific case =
for X (I'll assume X11 until corrected):
>=20
> ; diff /sys/src/ape/lib/ap/plan9/_buf.c _buf.c
> 292a293
>> printf("no buffered %d\n", i);
> 294a296
>> /*
> 298c300
> < 				errno =3D EBADF;		/* how X =
tells a client is gone */
> ---
>> 				errno =3D EBADF;		// how X =
tells a client is gone
> 300a303
>> */
>=20
>=20
>=20
> By removing the above, Python code that uses subprocess.Popen(cmd, =
stdout=3DPIPE, stderr=3DPIPE) will now work correctly, without having to =
resort to os.popen3(cmd) attempts to get around the select.error: (4, =
'Bad file number') that would crop up without the change.
>=20
> My question is: does anyone still use the X11 code based on APE?  Is =
this section safe to remove in sources?  Or do you have additional =
recommendations to work around the select() error?
>=20
> If not, I'll prep a patch.  Thanks.
>=20
> -jas
>=20
>=20