From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
To: Daniel Shahaf <d.s@daniel.shahaf.name>
Cc: "zsh-workers@zsh.org" <zsh-workers@zsh.org>,
Martin Tournoij <martin@arp242.net>
Subject: Re: Any way to allow clobbering empty files when noclobber is set?
Date: Fri, 5 Jun 2020 06:38:46 +0200 [thread overview]
Message-ID: <CAN=4vMoC8aNBz=ZAW-BdA9W6MaBXN3SNBPpZZQobVRwjUg2wGQ@mail.gmail.com> (raw)
In-Reply-To: <20200605020748.635b9bb3@tarpaulin.shahaf.local2>
On Fri, Jun 5, 2020 at 4:07 AM Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
>
> Roman Perepelitsa wrote on Thu, 04 Jun 2020 07:41 +0200:
>
> > Or how to implement clobber-if-empty without ever clobbering non-empty
> > files?
>
> By using a non-clobbering open(), then calling fstat() on the open fd.
> If it's zero length, just carry on. If it's not zero length, close()
> it and report an error.
Consider the following program:
write() print -rn -- $1
rm -f foo
write hello >foo &
write bye >foo &
wait
With regular no_clobber it has the following guarantees:
1. `write` is executed exactly once
2. once `wait` completes, `foo` contains either "hello" or "bye"
Is there a way to provide these guarantees with clobber_empty? (2) is
especially important. Seeing "byelo" or "hellobye" in `foo` would be
quite confusing. It would look like clobbering.
Roman.
next prev parent reply other threads:[~2020-06-05 4:39 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200603020919eucas1p13e26ebcbb335784d14bfb97b137f385a@eucas1p1.samsung.com>
2020-06-03 2:08 ` Martin Tournoij
2020-06-03 12:04 ` Peter Stephenson
2020-06-04 1:48 ` Daniel Shahaf
2020-06-04 2:43 ` Bart Schaefer
2020-06-04 4:06 ` Daniel Shahaf
2020-06-04 5:00 ` Bart Schaefer
2020-06-05 3:10 ` Daniel Shahaf
2020-06-05 3:18 ` Daniel Shahaf
2020-06-06 1:07 ` Bart Schaefer
2020-06-06 4:48 ` Daniel Shahaf
2020-06-06 7:04 ` Bart Schaefer
2020-06-04 6:31 ` Martin Tournoij
2020-06-05 2:22 ` Daniel Shahaf
2020-06-04 2:13 ` Vin Shelton
2020-06-04 2:35 ` Bart Schaefer
2020-06-04 2:36 ` Daniel Shahaf
2020-06-04 11:57 ` Vin Shelton
2020-06-04 5:06 ` Bart Schaefer
2020-06-04 5:41 ` Roman Perepelitsa
2020-06-05 2:07 ` Daniel Shahaf
2020-06-05 4:38 ` Roman Perepelitsa [this message]
2020-06-06 1:41 ` Bart Schaefer
2020-06-06 4:55 ` Daniel Shahaf
2020-06-06 6:25 ` Roman Perepelitsa
2020-06-06 7:08 ` Bart Schaefer
2020-06-06 8:03 ` Daniel Shahaf
[not found] ` <1941572212.466119.1591360860372@mail2.virginmedia.com>
[not found] ` <e7f7dfe2-eb4a-457b-85fb-091935a74c0e@www.fastmail.com>
2020-06-06 11:57 ` Peter Stephenson
2020-06-06 12:48 ` Roman Perepelitsa
2020-06-06 15:24 ` Bart Schaefer
2020-06-06 16:24 ` Peter Stephenson
2020-06-07 11:55 ` Daniel Shahaf
2020-06-07 17:00 ` Peter Stephenson
2020-06-08 3:27 ` Daniel Shahaf
2020-06-08 9:30 ` Peter Stephenson
2020-06-07 17:20 ` Bart Schaefer
2020-06-06 15:09 ` Bart Schaefer
2020-06-04 6:47 ` Martin Tournoij
2020-06-04 9:42 ` Peter Stephenson
2020-06-04 12:20 ` Roman Perepelitsa
2020-06-04 12:26 ` Peter Stephenson
2020-06-04 12:15 ` Peter Stephenson
2020-06-04 20:35 ` Bart Schaefer
2020-06-05 1:59 ` Daniel Shahaf
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