[LTP] [PATCH v1] tst_net.sh: Add more tst_require_cmds check

[Petr Vorel]

> On Tue, Jan 17, 2023 at 09:33:14AM +0100, Petr Vorel wrote:
> > Hi Wei,

> > > More strict check for ns_xxx etc will help avoid following issue:
> > > https://github.com/linux-test-project/ltp/issues/991

> > > Signed-off-by: Wei Gao <wegao@suse.com>
> > > Suggested-by: Petr Vorel <pvorel@suse.cz>
> > > ---
> > >  testcases/lib/tst_net.sh | 2 ++
> > >  1 file changed, 2 insertions(+)

> > > diff --git a/testcases/lib/tst_net.sh b/testcases/lib/tst_net.sh
> > > index ceb45c98d..ec915ad74 100644
> > > --- a/testcases/lib/tst_net.sh
> > > +++ b/testcases/lib/tst_net.sh
> > > @@ -205,6 +205,7 @@ tst_rhost_run()
> > >  	sh_cmd="$pre_cmd $cmd $post_cmd"

> > >  	if [ -n "${TST_USE_NETNS:-}" ]; then
> > > +		tst_require_cmds ip ns_create ns_exec ns_ifmove
> > Why this? none of these commands is used here.
> This line is the key to avoid wrong configuration(such as add ip inteface etc..) continue even ns_xxx not exist,
> you can check following code, line 222 will execute ns_xxx with error but not exit test immediately, so if we add 
> require_cmds here then we can avoid it. (line 222 $rcmd will contain command ns_xxx)

>  218                 tst_res_ TINFO "tst_rhost_run: cmd: $cmd"
>  219                 tst_res_ TINFO "$use: $rcmd \"$sh_cmd\" $out 2>&1"
>  220         fi
>  221
>  222         output=$($rcmd "$sh_cmd" $out 2>&1 || echo 'RTERR')
>  223
>  224         echo "$output" | grep -q 'RTERR$' && ret=1
>  225         if [ $ret -eq 1 ]; then

Long time ago the first run code for netns was init_ltp_netspace.
I added IPv6 check quite recently. (I originally submitted it as run after, but
in the end it is run before it.)
I need to have a deeper look how tst_net_detect_ipv6 rhost works, calling
tst_rhost_run before init_ltp_netspace should not work (interfaces aren't
configured yet).

But even if "ip ns_create ns_exec ns_ifmove" are needed to be checked to fix
tst_rhost_run (not yet convinced), why to check them each time tst_rhost_run is
called? It should be checked before first tst_rhost_run call to avoid useless
repeating.

Kind regards,
Petr

> > >  		use="NETNS"
> > >  		rcmd="$LTP_NETNS sh -c"
> > >  	else
> > > @@ -1006,6 +1007,7 @@ IPV6_RHOST="${IPV6_RHOST:-fd00:1:1:1::1/64}"
> > >  # tst_net_iface_prefix -h
> > >  # tst_net_vars -h
> > >  if [ -z "$_tst_net_parse_variables" ]; then
> > > +	tst_require_cmds tst_net_ip_prefix
> > This is correct.

> > Kind regards,
> > Petr