svn commit: r243228 - head/etc

[Bruce Evans]

On Tue, 20 Nov 2012, John Hay wrote:

> On Sun, Nov 18, 2012 at 02:21:05PM +0000, Chris Rees wrote:
>> Log:
>>   cp -R misses out dotfiles; use pax instead to copy file hierarchies
>>
>>   PR:		conf/99721 (based on)
>>   Submitted by:	Florian Zavatzki <f_zavatzki at blue-network.org>
>>   Approved by:	hrs
>>   MFC after:	1 month
>>
>> Modified:
>>   head/etc/rc.initdiskless
>>
>> Modified: head/etc/rc.initdiskless
>> ==============================================================================
>> --- head/etc/rc.initdiskless	Sun Nov 18 14:05:28 2012	(r243227)
>> +++ head/etc/rc.initdiskless	Sun Nov 18 14:21:05 2012	(r243228)
>> @@ -354,7 +354,7 @@ for i in ${templates} ; do
>>  	subdir=${j##*/}
>>  	if [ -d $j -a ! -f $j.cpio.gz  ]; then
>>  	    create_md $subdir
>> -	    cp -Rp $j/ /$subdir
>> +	    (cd $j && pax -rw . /$subdir)
>>  	fi
>>      done
>>      for j in /conf/$i/*.cpio.gz ; do
>
> Have you tested this on a diskless and readonly system? It looks like pax
> need to write something in /tmp and it might not be writeable yet. I got
> an error, after the first of /bin/pax not found and having to add that to
> the list of files needed.

It uses mkstemp(3), normally in /tmp but it honors $TMPDIR.  It seems to
always create 1 temporary file (even for copying a single regular file),
and sometimes 2 temporary files.  Both of the temporary files seem to be
to hold metadata for file times and hashes, in case it is too large for
memory.  cp -Rp probably needs to do the same (except it is imperfect to
unnecessarily assume that /tmp is writable), to fix its link and timestamp
handling.

BTW, I think it is a large bug that ed and vi create temporary files even
before you change anything.  Even view(1) (vi -R) wants to scribble on
/var/tmp/vi.recover.  At least it doesn't refuse to start if this is not
writeable.  ed(1) is considerably more broken.  It
- hard codes /tmp and doesn't use _PATH_TMP or honor $TMPDIR
- always scribbles in /tmp
- refuses to start if /tmp is not writeable.
This makes ed(1) wlays broken in single user shells until '/' is mounted
rw, although ed is the only editor that is sure to be there and the
reason for using a single user shell is often that there is a problem
with mounting '/' rw.

Bruce