Date: Mon, 24 Jul 2006 21:13:01 +0400 From: Yar Tikhiy <yar@comp.chem.msu.su> To: freebsd-rc@FreeBSD.org Subject: Order of _nice, _user, and _chdir Message-ID: <20060724171301.GA52664@comp.chem.msu.su>
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Hi all, I saw a complaint in a Russian BSD newsgroup that it was impossible to assign a negative niceness to the $command process via $foo_nice whenever $foo_user was set to a non-root user. So I took a look at the part of rc.subr dealing with the start of $command. As of now, the order of processing foo_chdir, foo_nice, and foo_user is as follows: user ( chdir ; nice ( command ) ) E.g.: su -m $foo_user -c 'sh -c "cd $foo_chdir ; nice -n $foo_nice $command"' Therefore the command's process(es) may not be assigned a negative niceness because nice(1) is run as the unprivileged $foo_user. In addition, a failure to chdir() will be ignored. IMHO a better order would be: nice ( user ( chdir && command ) ) E.g.: nice -n $foo_nice su -m $foo_user -c 'sh -c "cd $foo_chdir && $command"' nice -n $foo_nice sh -c "cd $foo_chdir && $command" # w/o foo_user The respective patch is attached. Any comments? Thanks. -- Yar Index: rc.subr =================================================================== RCS file: /home/ncvs/src/etc/rc.subr,v retrieving revision 1.59 diff -u -p -r1.59 rc.subr --- rc.subr 21 Jun 2006 09:42:55 -0000 1.59 +++ rc.subr 24 Jul 2006 15:30:53 -0000 @@ -666,12 +666,17 @@ chroot ${_user:+-u $_user }${_group:+-g $_chroot $command $rc_flags $command_args" else _doit="\ -${_chdir:+cd $_chdir; }\ -${_nice:+nice -n $_nice }\ +${_chdir:+cd $_chdir && }\ $command $rc_flags $command_args" if [ -n "$_user" ]; then _doit="su -m $_user -c 'sh -c \"$_doit\"'" fi + if [ -n "$_nice" ]; then + if [ -z "$_user" ]; then + _doit="sh -c \"$_doit\"" + fi + _doit="nice -n $_nice $_doit" + fi fi # if the cmd failed and force
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