GNU bug report logs - #33287
[PATCH] sync: add missing brackets in sync_arg()

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From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: 33287 <at> debbugs.gnu.org, eggert <at> cs.ucla.edu, kdudka <at> redhat.com
Subject: bug#33287: [PATCH] sync: add missing brackets in sync_arg()
Date: Wed, 7 Nov 2018 00:33:45 +0100

[Message part 1 (text/plain, inline)]

On 11/6/18 7:35 PM, Paul Eggert wrote:
> Thanks, I installed that and am closing the bug report.

That was a real bug, i.e., not only a resource leak, wasn't it?

If the calling user has -r+w permissions on the file, then sync previously
exited with 1 without actually syncing:

  $ install -m 0200 /dev/null /tmp/file

  $ ls -log /tmp/file
  --w------- 1 0 Nov  7 00:06 /tmp/file

  $ strace -v /usr/bin/sync /tmp/file 2>&1 | tail -n6
  openat(AT_FDCWD, "/tmp/file", O_RDONLY|O_NONBLOCK) = -1 EACCES (Permission denied)
  openat(AT_FDCWD, "/tmp/file", O_WRONLY|O_NONBLOCK) = 3
  close(1)                                = 0
  close(2)                                = 0
  exit_group(1)                           = ?
  +++ exited with 1 +++

With the patch, fsync is called, and sync terminated with success:

  $ strace -v src/sync /tmp/file 2>&1 | tail
  openat(AT_FDCWD, "/tmp/file", O_RDONLY|O_NONBLOCK) = -1 EACCES (Permission denied)
  openat(AT_FDCWD, "/tmp/file", O_WRONLY|O_NONBLOCK) = 3
  fcntl(3, F_GETFL)                       = 0x8801 (flags O_WRONLY|O_NONBLOCK|O_LARGEFILE)
  fcntl(3, F_SETFL, O_WRONLY|O_LARGEFILE) = 0
  fsync(3)                                = 0
  close(3)                                = 0
  close(1)                                = 0
  close(2)                                = 0
  exit_group(0)                           = ?
  +++ exited with 0 +++

Should we add a NEWS entry and a test - see attached?

Thanks & have a nice day,
Berny

[0001-sync-add-NEWS-and-test-for-the-fix-in-the-previous-c.patch (text/x-patch, attachment)]

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