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From: Bart Schaefer <schaefer@brasslantern.com>
To: "zsh-workers@zsh.org" <zsh-workers@zsh.org>
Cc: Martin Tournoij <martin@arp242.net>
Subject: Re: Any way to allow clobbering empty files when noclobber is set?
Date: Thu, 4 Jun 2020 13:35:22 -0700	[thread overview]
Message-ID: <CAH+w=7Yk6gbTKjzQ-N91X_hR_24wnBbxE+7TqrtoTc6cyocqmQ@mail.gmail.com> (raw)
In-Reply-To: <99742213.429535.1591272937010@mail2.virginmedia.com>

On Thu, Jun 4, 2020 at 5:16 AM Peter Stephenson
<p.w.stephenson@ntlworld.com> wrote:
>
> One thing I missed is that we already open the file and run fstat to
> check if it's regular.  We can simply check if it's empty at the
> same point

Exactly where my earlier question came from.

> +           if (isset(CLOBBEREMPTY) && buf.st_size == 0)
> +           {
> +               close(fd);
> +               return open(ufname, O_WRONLY | O_CREAT | O_TRUNC | O_NOCTTY,
> +                           0666);
> +           }

Considering the concurrent-openers situation that Roman mentioned, I'm
debating whether there is any benefit to doing:

  int newfd = open(ufname, O_WRONLY | O_CREAT | O_TRUNC | O_NOCTTY, 0666);
  close(fd);
  return newfd;

I have a vague sense that keeping the descriptor open until the new
file is created might prevent some races, but I can't recite an
example.

  reply	other threads:[~2020-06-04 20:36 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
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 [this message]
2020-06-05  1:59         ` Daniel Shahaf

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