_libvirt, $opt_args, and noglob

_libvirt, $opt_args, and noglob

[Daniel Shahaf]

The question mark in «noglob virsh -c foo://bar?» is interpreted by the
_call_program subshell as a pattern, causing _libvirt to fail to find
completions:

(setup)
% zstyle :completion:\*:warnings format 'No matches: %D'    
% functions -T $_comps[libvirt]

% noglob virsh -c qemu:///system? start --domain <TAB>
⋮
+_libvirt:142> values=+_libvirt:142> _call_program domains 'virsh -c qemu\:///system? list --inactive --name'
+_libvirt:142> values=( ) 
No matches: cmdopt

Now create a filename that matches that globbing pattern and try the
command again:

% noglob mkdir -p ./qemu:/system?
% noglob virsh -c qemu:///system? start --domain <TAB>
<works>

I believe the reason it works is that the globbing pattern «qemu:///system?»
gets expanded into the filename «qemu:/system?», which happens to work
just fine as an argument to «virsh -c».

(The backslash in front of the colon here is an independent problem, see 39158.)

In the special case of _libvirt, simply adding noglob to the
_call_program arguments would probably fix this.  This might not work
for arbitrary other callsites, though.  I think the general fix would be
to backslash-escape the characters that "need escaping only when noglob
is not present".  (Neither (q) nor (b) do this since both of them escape
backslashes.)

Cheers,

Daniel

Re: _libvirt, $opt_args, and noglob

[Daniel Shahaf]

Daniel Shahaf wrote on Sun, Sep 04, 2016 at 18:26:22 +0000:
> In the special case of _libvirt, simply adding noglob to the
> _call_program arguments would probably fix this.

Done, but the last line touches the sudo invocation from Oliver's
gain-privileges patch.  Oliver: shall I wait with committing this until
you've committed gain-privileges?

[[[
diff --git a/Completion/Unix/Command/_libvirt b/Completion/Unix/Command/_libvirt
index 658e197..2a0a34c 100644
--- a/Completion/Unix/Command/_libvirt
+++ b/Completion/Unix/Command/_libvirt
@@ -140,51 +140,51 @@ case $state in
     local -a values
     case $words[CURRENT-1] in
       --domain)
-        values=( $(_call_program domains "virsh $conn_opt list ${dom_opts[$cmd]:-"--all"} --name") )
+        values=( $(_call_program domains "noglob virsh $conn_opt list ${dom_opts[$cmd]:-"--all"} --name") )
         [[ -n $values ]] && _wanted domains expl domain compadd ${=values} && return 0
         return 1
       ;;
       --interface)
-        values=( ${${${${(f):-"$(_call_program interfaces "virsh $conn_opt iface-list ${iface_opts[$cmd]:-"--all"}")"}/ Name*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program interfaces "noglob virsh $conn_opt iface-list ${iface_opts[$cmd]:-"--all"}")"}/ Name*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted interfaces expl interface compadd ${=values} && return 0
         return 1
       ;;
       --network)
-        values=( $(_call_program networks "virsh $conn_opt net-list ${net_opts[$cmd]:-"--all"} --name") )
+        values=( $(_call_program networks "noglob virsh $conn_opt net-list ${net_opts[$cmd]:-"--all"} --name") )
         [[ -n $values ]] && _wanted networks expl network compadd ${=values} && return 0
         return 1
       ;;
       --device)
-        values; values=( $(_call_program nodedevs "virsh $conn_opt nodedev-list") )
+        values; values=( $(_call_program nodedevs "noglob virsh $conn_opt nodedev-list") )
         [[ -n $values ]] && _wanted devices expl device compadd ${=values} && return 0
         return 1
       ;;
       --nwfilter)
-        values=( ${${${${(f):-"$(_call_program nwfilters "virsh $conn_opt nwfilter-list")"}/ UUID*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program nwfilters "noglob virsh $conn_opt nwfilter-list")"}/ UUID*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted nwfilters expl nwfilter compadd ${=values} && return 0
         return 1
       ;;
       --pool)
-        values=( ${${${${(f):-"$(_call_program pools "virsh $conn_opt pool-list ${pool_opts[$cmd]:-"--all"}")"}/ Name*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program pools "noglob virsh $conn_opt pool-list ${pool_opts[$cmd]:-"--all"}")"}/ Name*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted pools expl pool compadd ${=values} && return 0
         return 1
       ;;
       --secret)
-        values=( ${${${${(f):-"$(_call_program secrets "virsh $conn_opt secret-list")"}/ UUID*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program secrets "noglob virsh $conn_opt secret-list")"}/ UUID*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted secrets expl secret compadd ${=values} && return 0
         return 1
       ;;
       --snapshotname)
         local dom ; (( ${(k)words[(I)--domain]} > 0 )) && dom=${words[1+${(k)words[(I)--domain]}]}
         [[ -z $dom ]] && return 1
-        values=( ${${${${(f):-"$(_call_program snapshots "virsh $conn_opt snapshot-list --domain ${(q)dom} 2>/dev/null")"}/ Name*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program snapshots "noglob virsh $conn_opt snapshot-list --domain ${(q)dom} 2>/dev/null")"}/ Name*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted snapshots expl snapshot compadd ${=values} && return 0
         return 1
       ;;
       --vol)
         local pool ; (( ${(k)words[(I)--pool]} > 0 )) && pool=${words[1+${(k)words[(I)--pool]}]}
         [[ -z $pool ]] && return 1
-        values=( ${${${${(f):-"$(_call_program volumes "virsh $conn_opt vol-list --pool ${(q)pool} 2>/dev/null")"}/ Name*/}:#---*}/  */} )
+        values=( ${${${${(f):-"$(_call_program volumes "noglob virsh $conn_opt vol-list --pool ${(q)pool} 2>/dev/null")"}/ Name*/}:#---*}/  */} )
         [[ -n $values ]] && _wanted volumes expl volume compadd ${=values} && return 0
         return 1
       ;;
@@ -199,7 +199,7 @@ case $state in
     # Allow passing domain without --domain with few of the most used commands
     if [[ $cmd == (destroy|reboot|reset|start|shutdown) ]]; then
       if [[ $words[CURRENT-1] == $cmd ]]; then
-        values=( $(_call_program domains "virsh $conn_opt list ${dom_opts[$cmd]:-"--all"} --name") )
+        values=( $(_call_program domains "noglob virsh $conn_opt list ${dom_opts[$cmd]:-"--all"} --name") )
         [[ -n $values ]] && _wanted domains expl domain compadd ${=values} && return 0
       fi
     fi
@@ -224,7 +224,7 @@ case $state in
       local srv ; (( ${(k)words[(I)--server]} > 0 )) && srv=${words[1+${(k)words[(I)--server]}]}
       [[ -z $srv ]] && return 1
       [[ -n ${srv//[[:alnum:]]} ]] && return 1
-      _wanted clients expl client compadd ${=${${(f):-"$(sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
+      _wanted clients expl client compadd ${=${${(f):-"$(noglob sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
     fi
     [[ -z $_cache_virt_admin_cmd_opts[$cmd] ]] && \
       _cache_virt_admin_cmd_opts[$cmd]=${(M)${${${${=${(f)"$(_call_program virt-admin virt-admin help $cmd 2>&1)"}}/\[}/\]}/\;}:#-[-0-9A-Za-z]*}
]]]

> This might not work for arbitrary other callsites, though.  I think
> the general fix would be to backslash-escape the characters that "need
> escaping only when noglob is not present".  (Neither (q) nor (b) do
> this since both of them escape backslashes.)

Leaving this for Future Work.

Cheers,

Daniel

Re: _libvirt, $opt_args, and noglob

[Marko Myllynen]

Hi,

On 2016-09-07 02:46, Daniel Shahaf wrote:
> Daniel Shahaf wrote on Sun, Sep 04, 2016 at 18:26:22 +0000:
>> In the special case of _libvirt, simply adding noglob to the
>> _call_program arguments would probably fix this.
> 
> Done, but the last line touches the sudo invocation from Oliver's
> gain-privileges patch.  Oliver: shall I wait with committing this until
> you've committed gain-privileges?
> 
> @@ -224,7 +224,7 @@ case $state in
>        local srv ; (( ${(k)words[(I)--server]} > 0 )) && srv=${words[1+${(k)words[(I)--server]}]}
>        [[ -z $srv ]] && return 1
>        [[ -n ${srv//[[:alnum:]]} ]] && return 1
> -      _wanted clients expl client compadd ${=${${(f):-"$(sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
> +      _wanted clients expl client compadd ${=${${(f):-"$(noglob sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
>      fi
>      [[ -z $_cache_virt_admin_cmd_opts[$cmd] ]] && \
>        _cache_virt_admin_cmd_opts[$cmd]=${(M)${${${${=${(f)"$(_call_program virt-admin virt-admin help $cmd 2>&1)"}}/\[}/\]}/\;}:#-[-0-9A-Za-z]*}
> ]]]

Do we need any of (Q)'s there any more after your addition of:

  uri=${uri//(#m)\\([\\:])/${MATCH[2]}} # opt_args elements are colon-escaped

Based on a quick test looks like they could be dropped (or
perhaps even changed to (q))?

Thanks,

-- 
Marko Myllynen

Re: _libvirt, $opt_args, and noglob

[Daniel Shahaf]

See the penultimate paragraph for a question about whether ${(q)} should
quote leading '=' signs to guard against the EQUALS option.

Marko Myllynen wrote on Wed, Sep 07, 2016 at 12:53:13 +0300:
> Hi,
> 
> On 2016-09-07 02:46, Daniel Shahaf wrote:
> > Daniel Shahaf wrote on Sun, Sep 04, 2016 at 18:26:22 +0000:
> >> In the special case of _libvirt, simply adding noglob to the
> >> _call_program arguments would probably fix this.
> > 
> > Done, but the last line touches the sudo invocation from Oliver's
> > gain-privileges patch.  Oliver: shall I wait with committing this until
> > you've committed gain-privileges?
> > 
> > @@ -224,7 +224,7 @@ case $state in
> >        local srv ; (( ${(k)words[(I)--server]} > 0 )) && srv=${words[1+${(k)words[(I)--server]}]}
> >        [[ -z $srv ]] && return 1
> >        [[ -n ${srv//[[:alnum:]]} ]] && return 1
> > -      _wanted clients expl client compadd ${=${${(f):-"$(sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
> > +      _wanted clients expl client compadd ${=${${(f):-"$(noglob sudo virt-admin ${(Q)conn_opt} srv-clients-list --server $srv 2>/dev/null)"}/ [a-z]*}//[^0-9]} && return 0
> >      fi
> >      [[ -z $_cache_virt_admin_cmd_opts[$cmd] ]] && \
> >        _cache_virt_admin_cmd_opts[$cmd]=${(M)${${${${=${(f)"$(_call_program virt-admin virt-admin help $cmd 2>&1)"}}/\[}/\]}/\;}:#-[-0-9A-Za-z]*}
> > ]]]
> 
> Do we need any of (Q)'s there any more after your addition of:
> 
>   uri=${uri//(#m)\\([\\:])/${MATCH[2]}} # opt_args elements are colon-escaped
> 
> Based on a quick test looks like they could be dropped (or
> perhaps even changed to (q))?

_call_program expects its argument to be (q)'d.  (The interface is like
'eval', not like execve(2).)

The values of $opt_args are *already* (q)'d.  If the command line is
«virsh -c foo\\bar» then the value of $pot_args[-c] includes two
backslashes, not one as virsh(1)'s argv[2] would see.¹

Therefore, I think the correct way to pass values derived from $opt_args
— this includes $conn_opt — to _call_program is to use neither (q) nor (Q).

That is the general answer.  For the specific case of $conn_opt, the URI
format validator ensures it has nothing that needs quoting, apart from
'?' and '=', and the patch in the grandparent message removes the need
for '?' to be quoted.  However, there's no easy to to quote '=' when
it's the first character of a word, and _call_program does honour the
EQUALS option:
.
    % _f() { compadd - $(_call_program x 'echo =true') }
    % f <TAB>
    <becomes>
    % f /bin/true

Again, this is harmless as far as _libvirt is concerned, but it might
not be so in other callsites.  I think the right general solution to
this would be to write ${(q)${(Q)conn_opts}} in the _call_program
invocation, and teach the (q) flag to escape leading equals signs.

Anyway, back to Marko's question: I assume even if the EQUALS option did
affect the command executed, that wouldn't cause any harm, so I think
the primary reason to get _libvirt's quoting right is in case somebody
ever uses _libvirt as a basis for some other completion function.
That's part of why I committed the (b) patch, too.

Cheers,

Daniel

¹ This assumes that the word being completed, $CURRENT, is not the
argument to -c, in which cae $opt_args[-c] could have an opening quote
but no matching closing quote.