From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <bbbd182389f4ba4d3afab92be277012a@collyer.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] what a mess the Unix world has become
From: Geoff Collyer <geoff@collyer.net>
In-Reply-To: <3E48ABC5.6050205@null.net>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Date: Tue, 11 Feb 2003 02:25:20 -0800
Topicbox-Message-UUID: 56ad3110-eacb-11e9-9e20-41e7f4b1d025

Checking close() return values after writing on a descriptor is good
hygiene, but as I recall, NFS made error detection harder by not
necessarily reporting write errors (even synchronous ones like ENOSPC)
via either write() or close(); one had to use fsync() just before the
close() to force any write errors to be reported.

 From code I wrote in the late 1980s:

/*
 * nfclose(stream) - flush the stream, fsync its file descriptor and
 * fclose the stream, checking for errors at all stages.  This dance
 * is needed to work around the lack of Unix file system semantics
 * in Sun's NFS.  Returns EOF on error.
 */

#include <stdio.h>

int
nfclose(stream)
register FILE *stream;
{
	register int ret = 0;

	if (fflush(stream) == EOF)
		ret = EOF;
	if (fsync(fileno(stream)) < 0)		/* may get delayed error here */
		ret = EOF;
	if (fclose(stream) == EOF)
		ret = EOF;
	return ret;
}