CMake/Utilities/Scripts/update-third-party.bash

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########################################################################
# Script for updating third party packages.
#
# This script should be sourced in a project-specific script which sets
# the following variables:
#
# name
# The name of the project.
# ownership
# A git author name/email for the commits.
# subtree
# The location of the thirdparty package within the main source
# tree.
# repo
# The git repository to use as upstream.
# tag
# The tag, branch or commit hash to use for upstream.
# shortlog
# Optional. Set to 'true' to get a shortlog in the commit message.
#
# Additionally, an "extract_source" function must be defined. It will be
# run within the checkout of the project on the requested tag. It should
# should place the desired tree into $extractdir/$name-reduced. This
# directory will be used as the newest commit for the project.
#
# For convenience, the function may use the "git_archive" function which
# does a standard "git archive" extraction using the (optional) "paths"
# variable to only extract a subset of the source tree.
########################################################################
########################################################################
# Utility functions
########################################################################
git_archive () {
git archive --prefix="$name-reduced/" HEAD -- $paths | \
tar -C "$extractdir" -x
}
die () {
echo >&2 "$@"
exit 1
}
warn () {
echo >&2 "warning: $@"
}
readonly regex_date='20[0-9][0-9]-[0-9][0-9]-[0-9][0-9]'
readonly basehash_regex="$name $regex_date ([0-9a-f]*)"
readonly basehash="$( git rev-list --author="$ownership" --grep="$basehash_regex" -n 1 HEAD )"
readonly upstream_old_short="$( git cat-file commit "$basehash" | sed -n '/'"$basehash_regex"'/ {s/.*(//;s/)//;p}' | egrep '^[0-9a-f]+$' )"
########################################################################
# Sanity checking
########################################################################
[ -n "$name" ] || \
die "'name' is empty"
[ -n "$ownership" ] || \
die "'ownership' is empty"
[ -n "$subtree" ] || \
die "'subtree' is empty"
[ -n "$repo" ] || \
die "'repo' is empty"
[ -n "$tag" ] || \
die "'tag' is empty"
[ -n "$basehash" ] || \
warn "'basehash' is empty; performing initial import"
readonly do_shortlog="${shortlog-false}"
readonly workdir="$PWD/work"
readonly upstreamdir="$workdir/upstream"
readonly extractdir="$workdir/extract"
[ -d "$workdir" ] && \
die "error: workdir '$workdir' already exists"
trap "rm -rf '$workdir'" EXIT
# Get upstream
git clone "$repo" "$upstreamdir"
if [ -n "$basehash" ]; then
# Use the existing package's history
git worktree add "$extractdir" "$basehash"
# Clear out the working tree
pushd "$extractdir"
git ls-files | xargs rm -v
popd
else
# Create a repo to hold this package's history
mkdir -p "$extractdir"
git -C "$extractdir" init
fi
# Extract the subset of upstream we care about
pushd "$upstreamdir"
git checkout "$tag"
readonly upstream_hash="$( git rev-parse HEAD )"
readonly upstream_hash_short="$( git rev-parse --short=8 "$upstream_hash" )"
readonly upstream_datetime="$( git rev-list "$upstream_hash" --format='%ci' -n 1 | grep -e "^$regex_date" )"
readonly upstream_date="$( echo "$upstream_datetime" | grep -o -e "$regex_date" )"
if $do_shortlog && [ -n "$basehash" ]; then
readonly commit_shortlog="
Upstream Shortlog
-----------------
$( git shortlog --no-merges --abbrev=8 --format='%h %s' "$upstream_old_short".."$upstream_hash" )"
else
readonly commit_shortlog=""
fi
extract_source || \
die "failed to extract source"
popd
[ -d "$extractdir/$name-reduced" ] || \
die "expected directory to extract does not exist"
readonly commit_summary="$name $upstream_date ($upstream_hash_short)"
# Commit the subset
pushd "$extractdir"
mv -v "$name-reduced/"* .
rmdir "$name-reduced/"
git add -A .
git commit -n --author="$ownership" --date="$upstream_datetime" -F - <<-EOF
$commit_summary
Code extracted from:
$repo
at commit $upstream_hash ($tag).$commit_shortlog
EOF
git branch -f "upstream-$name"
popd
# Merge the subset into this repository
if [ -n "$basehash" ]; then
git merge --log -s recursive "-Xsubtree=$subtree/" --no-commit "upstream-$name"
else
git fetch "$extractdir" "upstream-$name:upstream-$name"
git merge --log -s ours --no-commit "upstream-$name"
git read-tree -u --prefix="$subtree/" "upstream-$name"
fi
git commit --no-edit
git branch -d "upstream-$name"