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From: Vincent Lefevre <vincent@vinc17.net>
To: zsh-users@zsh.org
Subject: Re: No fsync on history file? I lost my history
Date: Sun, 23 Sep 2018 21:40:19 +0200	[thread overview]
Message-ID: <20180923194018.GA18586@zira.vinc17.org> (raw)
In-Reply-To: <1537717517.130522.1517748104.07A63DB4@webmail.messagingengine.com>

On 2018-09-23 15:45:17 +0000, Daniel Shahaf wrote:
> > > > +++ b/Src/hist.c
> > > > @@ -2933,6 +2933,9 @@ savehistfile(char *fn, int err, int writeflags)
> > > >  		lasthist.text = ztrdup(start);
> > > >  	    }
> > > >  	}
> > > > +	fflush(out); /* need to flush before fsync */
> > > 
> > > Isn't the fflush() on line 2927 sufficient?  (Even if it isn't, I would have
> > > expected a ret>=0 guard around this call.)
> > 
> > It should call write(2) to write out the buffered data. Then the kernel
> > can fsync the data to disk. A guard has been added.
> 
> Yes, I understand that fflush(3) must be called in order to flush data
> from libc's buffers into kernel buffers, which fsync(2) will later flush
> to disk.  My question was whether the fflush() call being added was
> redundant because of the existing call on line 2927.  It would be odd
> to have two fflush() calls in a row without fwrite() between them; and
> to have only one of them update lasthist.

But the first one is in a "if", thus might have not been called. Or
there is an inconsistency in the conditions, which should be fixed.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

  reply	other threads:[~2018-09-23 19:40 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-23  8:52 lilydjwg
2018-09-23 13:35 ` Daniel Shahaf
2018-09-23 14:22   ` lilydjwg
2018-09-23 14:46     ` Daniel Shahaf
2018-09-23 15:25       ` lilydjwg
2018-09-23 15:45         ` Daniel Shahaf
2018-09-23 19:40           ` Vincent Lefevre [this message]
2018-09-24  3:03             ` lilydjwg
2018-09-23 18:02         ` Mikael Magnusson
2018-09-24  3:04           ` lilydjwg

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