[pacman-dev] [PATCH 2/7] libmakepkg: stop printsrcinfo generating empty values

[Dave Reisner]

On Fri, Jun 08, 2018 at 08:42:11PM +0100, Morgan Adamiec wrote:
> On Fri, 8 Jun 2018 at 20:33, Eli Schwartz <eschwartz at archlinux.org> wrote:
> >
> > On 06/08/2018 02:18 PM, morganamilo wrote:
> > > When a split package overriddes an array using += and the array does not
> > > exist globally, makepkg --printsrcinfo will print the field with an
> > > empty vlaue before printing the acual values.
> > >
> > > For exampple: having `depends+=(foo bar)` will generate:
> > >       depends =
> > >       depends = foo
> > >       depends = bar
> > >
> > > Explicity check for empty array values and only print the values that
> > > are not empty.
> > >
> > > Signed-off-by: morganamilo <morganamilo at gmail.com>
> > > ---
> > >  scripts/libmakepkg/srcinfo.sh.in | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/scripts/libmakepkg/srcinfo.sh.in b/scripts/libmakepkg/srcinfo.sh.in
> > > index 509c4860..6a49be37 100644
> > > --- a/scripts/libmakepkg/srcinfo.sh.in
> > > +++ b/scripts/libmakepkg/srcinfo.sh.in
> > > @@ -44,7 +44,11 @@ srcinfo_write_attr() {
> > >       attrvalues=("${attrvalues[@]#[[:space:]]}")
> > >       attrvalues=("${attrvalues[@]%[[:space:]]}")
> > >
> > > -     printf "\t$attrname = %s\n" "${attrvalues[@]}"
> > > +     for val in "${attrvalues[@]}"; do
> > > +             if [[ ! -z ${val// /} ]]; then
> > > +                     printf "\t$attrname = %s\n" "$val"
> > > +             fi
> > > +     done
> >
> > This is odd, I wonder why get_pkgbuild_attribute is returning an
> > array=('' foo bar) in this case? We should probably fix it more directly.
> >
> > --
> > Eli Schwartz
> > Bug Wrangler and Trusted User
> >
> 
> In my investigation it came down to lines like this
> https://git.archlinux.org/pacman.git/tree/scripts/libmakepkg/srcinfo.sh.in#n55
> 
> It seems appending an array to a non array value generates an array
> with the first value being an empty string then the values appended.
> 
> You can reproduce it with:
>     foo=
>     foo+=(bar)
>     echo "${#foo[@]}"
> 
> I did think about fixing it there, but that function is used all over
> and I didn't want to break something.

That's just bad shell code. Using foo= to declare an array is the same
as writing foo=('').

Please don't change this to paper over bad PKGBUILDs. If anything, the
fix here is to leverage bash 4.4 in our lint rules when it's available
and use @a expansion to detect if something is an array or a string,
e.g.

$ licenses='MIT'
$ [[ ${licenses at a} = *a* ]] || echo "licenses must be an array"