[pacman-dev] [PATCH] makepkg: avoid using comm for diff'ing package lists

[Dan McGee]

On Tue, Nov 22, 2011 at 12:33 AM, Allan McRae <allan at archlinux.org> wrote:
> On 22/11/11 15:02, Dave Reisner wrote:
>>
>> Whereas comm will check inputs to see if they're sorted (and warn when
>> they aren't), grep doesn't even care about ordering. In this particular
>> instance -- neither do we. We're only interested that the two lists are
>> equivalent.
>>
>> Fixes FS#26580.
>>
>> Signed-off-by: Dave Reisner<dreisner at archlinux.org>
>> ---
>
> I had not seen this when I sent my patch.   Would comm not be more efficient
> than grep for doing this?
I don't think your patch actually fixes the underlying problem, which
is that the sorts need to come back too and be consistent with
whatever we tell comm it should expect. No matter what, makepkg
shouldn't really assume anything regarding the ordering of pacman
output- The LC_COLLATE=C should be added to both the comm calls and
re-add a `| LC_COLLATE=C sort` call to -Qq output.

grep avoids this completely; ordering doesn't matter at all. Perhaps
it is a bit less efficient, but this is 1) an operation that runs
once, and 2) the grep call is sticking to POSIX-conforming flags.

>>  scripts/makepkg.sh.in |   16 +++++++++-------
>>  1 files changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/scripts/makepkg.sh.in b/scripts/makepkg.sh.in
>> index 26a2789..0fa05dc 100644
>> --- a/scripts/makepkg.sh.in
>> +++ b/scripts/makepkg.sh.in
>> @@ -506,15 +506,17 @@ remove_deps() {
>>
>>        # check for packages removed during dependency install (e.g. due to
>> conflicts)
>>        # removing all installed packages is risky in this case
>> -       if [[ -n  $(comm -23<(printf "%s\n" "${original_pkglist[@]}") \
>> -                       <(printf "%s\n" "${current_pkglist[@]}")) ]]; then
>> -         warning "$(gettext "Failed to remove installed dependencies.")"
>> -         return 0
>> +       if [[ -n $(grep -xvFf<(printf '%s\n' "${current_packagelist[@]}")
>> \
>> +                       <(printf '%s\n' "${original_packagelist[@]}") )
>> ]]; then
>> +               warning "$(gettext "Failed to remove installed
>> dependencies.")"
>> +               return 0
>>        fi
>>
>> -       local deplist=($(comm -13<(printf "%s\n" "${original_pkglist[@]}")
>> \
>> -                       <(printf "%s\n" "${current_pkglist[@]}")))
>> -       (( ${#deplist[@]} == 0 ))&&  return
>> +       local deplist
>> +       if ! deplist=($(grep -xvFf<(printf "%s\n"
>> "${original_pkglist[@]}") \
>> +                       <(printf "%s\n" "${current_pkglist[@]}"))); then
>> +               return
>> +       fi
>>
>>        msg "Removing installed dependencies..."
>>        # exit cleanly on failure to remove deps as package has been built
>> successfully
>
>
>