nixpkgs/pkgs/build-support/setup-hooks/set-source-date-epoch-to-latest.sh
Eelco Dolstra 81e530a749 Set SOURCE_DATE_EPOCH to latest source file
This provides a timestamp that's more useful than 1970-01-01 yet still
deterministic.
2016-01-05 17:21:48 +01:00

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updateSourceDateEpoch() {
local path="$1"
# FIXME: Support Darwin.
if ! [[ $system =~ linux ]]; then
exit 1
return
fi
# Get the last modification time of all regular files, sort them,
# and get the most recent. Maybe we should use
# https://github.com/0-wiz-0/findnewest here.
local -a res=($(find "$path" -type f -print0 | xargs -0 -r stat -c '%Y %n' | sort -n | tail -n1))
local time="${res[0]}"
local newestFile="${res[1]}"
# Update $SOURCE_DATE_EPOCH if the most recent file we found is newer.
if [ "$time" -gt "$SOURCE_DATE_EPOCH" ]; then
echo "setting SOURCE_DATE_EPOCH to timestamp $time of file $newestFile"
export SOURCE_DATE_EPOCH="$time"
# Warn if the new timestamp is too close to the present. This
# may indicate that we were being applied to a file generated
# during the build, or that an unpacker didn't restore
# timestamps properly.
local now="$(date +%s)"
if [ "$time" -gt $((now - 60)) ]; then
echo "warning: file $newestFile may be generated; SOURCE_DATE_EPOCH may be non-deterministic"
fi
fi
}
postUnpackHooks+=(_updateSourceDateEpochFromSourceRoot)
_updateSourceDateEpochFromSourceRoot() {
updateSourceDateEpoch "$sourceRoot"
}