ghup/update-index-state.sh

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#!/usr/bin/env bash
set -eu
status_message() {
printf "\\033[0;32m%s\\033[0m\\n" "$1"
}
error_message() {
printf "\\033[0;31m%s\\033[0m\\n" "$1"
}
SCRIPTPATH="$( cd "$(dirname "$0")" ; pwd -P )"
CACHE_LOCATION="${HOME}/.cabal/packages/hackage.haskell.org/01-index.cache"
if [ ! -f "${CACHE_LOCATION}" ] ; then
error_message "${CACHE_LOCATION} does not exist, did you run 'cabal update'?"
exit 1
fi
if [ ! -f "${SCRIPTPATH}/cabal.project" ] ; then
error_message "Could not find ${SCRIPTPATH}/cabal.project, skipping index state update."
exit 3
fi
cabal v2-update
arch=$(getconf LONG_BIT)
case "${arch}" in
32)
byte_size=4
magic_word="CABA1002"
;;
64)
byte_size=8
magic_word="00000000CABA1002"
;;
*)
error_message "Unknown architecture (long bit): ${arch}"
exit 2
;;
esac
# This is the logic to parse the binary format of 01-index.cache.
# The first word is a magic 'caba1002', the second one is the timestamp in unix epoch.
# Better than copying the cabal-install source code.
if [ "$(xxd -u -p -l${byte_size} -s 0 "${CACHE_LOCATION}")" != "${magic_word}" ] ; then
error_message "Magic word does not match!"
exit 4
fi
cache_timestamp=$(echo "ibase=16;obase=A;$(xxd -u -p -l${byte_size} -s ${byte_size} "${CACHE_LOCATION}")" | bc)
# If we got junk from the binary file, this should fail.
cache_date=$(date --utc --date "@${cache_timestamp}" "+%FT%TZ")
status_message "Updating index state in ${SCRIPTPATH}/cabal.project"
if grep -q "^index-state: .*" "${SCRIPTPATH}/cabal.project" ; then
awk '/index-state:/ {gsub(/.*/, "index-state: '${cache_date}'")}; { print }' "${SCRIPTPATH}/cabal.project" > "${SCRIPTPATH}/cabal.project.tmp"
mv "${SCRIPTPATH}/cabal.project.tmp" "${SCRIPTPATH}/cabal.project"
else
printf "index-state: %s\n" "${cache_date}" >> "${SCRIPTPATH}/cabal.project"
fi