NetBSD/distrib/sets/culldeps

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#!/bin/sh
#
# culldeps
#
# Filter redundant dependencies.
#
# Each line of input and output contains two syspkg names,
# where the first syspkg depends on the second syspkg.
#
# Emit all the dependencies on the standard input to the standard
# output EXCEPT the dependencies which can be derived from other
# dependencies by the transitive rule. For example, omit both A C
# and A D from
#
# A B
# B C
# C D
# A C
# A D
#
# because A C can be derived from A B and B C by transitivity,
# and A D can be derived from A B, B C, C D by transitivity.
#
prog="${0##*/}"
rundir="$(dirname "$0")" # ${0%/*} isn't good enough when there's no "/"
. "${rundir}/sets.subr"
SCRATCH="$(${MKTEMP} -d "/var/tmp/${prog}.XXXXXX")"
NEXTLEFTOVERS="${SCRATCH}/leftovers0"
LASTJOIN="${SCRATCH}/join0"
NEXTJOIN="${SCRATCH}/join1"
TAB=" "
${SORT} -k 1 > "${LASTJOIN}"
LEFTOVERS="${LASTJOIN}"
while [ "$(${WC} -l "${LASTJOIN}" | ${AWK} '{ print $1; }')" -ne 0 ]; do
#
# From dependencies X-requires-Y in ${LEFTOVERS} and Y-requires-Z in
# ${LASTJOIN}, produce dependencies X-requires-Z and write them to
# ${NEXTJOIN}.
#
${SORT} -k 2 < "${LEFTOVERS}" | \
${JOIN} -1 2 -2 1 -o '1.1 2.2' - "${LASTJOIN}" | \
${SORT} -u > "${NEXTJOIN}"
if [ ${DEBUG:-0} -gt 0 ]; then
echo >&2 "${prog}: ### begin filtered results ###"
${JOIN} -t "${TAB}" "${NEXTJOIN}" "${LEFTOVERS}" | ${SORT} 1>&2
echo >&2 "${prog}: ### end filtered results ###"
fi
#
# Filter out of ${LEFTOVERS} all of the dependencies X-requires-Z, which
# were produced in the previous step. Write the new leftovers to
# ${NEXTLEFTOVERS}.
#
${JOIN} -v 2 -t "${TAB}" "${NEXTJOIN}" "${LEFTOVERS}" | \
${SORT} -u > "${NEXTLEFTOVERS}"
#
# Swap output files before repeating.
#
LASTJOIN="${NEXTJOIN}"
if [ "$(basename "${NEXTJOIN}")" = join0 ]; then
NEXTJOIN="${SCRATCH}/join1"
else
NEXTJOIN="${SCRATCH}/join0"
fi
LEFTOVERS="${NEXTLEFTOVERS}"
if [ "$(basename "${NEXTLEFTOVERS}")" = leftovers0 ]; then
NEXTLEFTOVERS="${SCRATCH}/leftovers1"
else
NEXTLEFTOVERS="${SCRATCH}/leftovers0"
fi
done
#
# Output all of the dependencies that were not culled and clean up.
#
cat "${LEFTOVERS}"
rm -r "${SCRATCH}"