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Last active February 9, 2022 13:54
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Git submodule rewrite
#!/usr/bin/env bash
# This script builds on the excellent work by Lucas Jenß, described in his blog
# post "Integrating a submodule into the parent repository", but automates the
# entire process and cleans up a few other corner cases.
# https://x3ro.de/2013/09/01/Integrating-a-submodule-into-the-parent-repository.html
function usage(){
echo "Usage: $0 <submodule-name> [<submodule-branch>]"
echo "Merge a single branch of <submodule-name> into a repo, retaining file history."
echo "If provided then <submodule-branch> will be merged, otherwise master."
echo ""
echo "options:"
echo " -h, --help Print this message"
echo " -f, --force Skip the warning message (use with caution)"
echo " -v, --verbose Display verbose output"
}
function abort {
echo "$(tput setaf 1)$1$(tput sgr0)"
exit 1
}
function request_confirmation {
read -p "$(tput setaf 4)$1 (y/n) $(tput sgr0)"
[ "$REPLY" == "y" ] || abort "Aborted!"
}
function warn() {
cat << EOF
This script will convert your "${sub}" git submodule into
a simple subdirectory in the parent repository while retaining all
contents, file history and its own submodules.
The script will:
* delete the ${sub} submodule configuration from .gitmodules and
.git/config and commit it.
* rewrite the entire history of the ${sub} submodule so that all
paths are prefixed by ${path}.
This ensures that git log will correctly follow the original file
history.
* merge the submodule's tags into its parent repository and commit
each tag merge individually.
(only those tags are considered which are reachable from
the tip of ${sub}/${branch})
* merge the submodule into its parent repository and commit it.
* reinstate any of the submodule's own submodules as part of the parent
repository
NOTE: This script might completely garble your repository, so PLEASE apply
this only to a fresh clone of the repository where it does not matter if
the repo is destroyed. It would be wise to keep a backup clone of your
repository, so that you can reconstitute it if need be. You have been
warned. Use at your own risk.
EOF
request_confirmation "Do you want to proceed?"
}
function git_version_lte() {
OP_VERSION=$(printf "%03d%03d%03d%03d" $(echo "$1" | tr '.' '\n' | head -n 4))
GIT_VERSION=$(git version)
GIT_VERSION=$(printf "%03d%03d%03d%03d" $(echo "${GIT_VERSION#git version }" | sed -E "s/([0-9.]*).*/\1/" | tr '.' '\n' | head -n 4))
echo -e "${GIT_VERSION}\n${OP_VERSION}" | sort | head -n1
[ ${GIT_VERSION} -le ${OP_VERSION} ]
}
# Convert a url to an absolute url
#
# Parameters:
# $1: The url to check
# $2: The base url to use if $1 is a relative path
#
# Returns an absolute url
function absolute_url {
local url=$1
local base=$2
if [[ $url =~ \.\. ]]; then
echo "$base/$(basename $url)"
else
echo $url
fi
}
function main() {
if [ "${skip_warn}" != "true" ]; then
warn
fi
if [ "${verbose}" == "true" ]; then
set -x
fi
# Remove submodule and commit
git config -f .gitmodules --remove-section "submodule.${sub}"
if git config -f .git/config --get "submodule.${sub}.url"; then
git config -f .git/config --remove-section "submodule.${sub}"
fi
rm -rf "${path}"
git add -A .
git commit -m "Remove submodule ${sub}"
rm -rf ".git/modules/${sub}"
# Rewrite submodule history
local tmpdir="$(mktemp -d -t submodule-rewrite-XXXXXX)"
git clone -b "${branch}" "${url}" "${tmpdir}"
# Be sure to get all tags as well as we will mege them later on
git fetch --tags -f
pushd "${tmpdir}"
local tab="$(printf '\t')"
local filter="git ls-files -s | sed \"s:${tab}:${tab}${path}/:\" | GIT_INDEX_FILE=\${GIT_INDEX_FILE}.new git update-index --index-info && mv \${GIT_INDEX_FILE}.new \${GIT_INDEX_FILE} || true"
git filter-branch --index-filter "${filter}" HEAD
popd
# Merge in rewritten submodule history
git remote add "${sub}" "${tmpdir}"
git fetch --tags "${sub}" -f
if git_version_lte 2.8.4
then
# Previous to git 2.9.0 the parameter would yield an error
ALLOW_UNRELATED_HISTORIES=""
else
# From git 2.9.0 this parameter is required
ALLOW_UNRELATED_HISTORIES="--allow-unrelated-histories"
fi
# First merge all tags
# We only consider tags reachable from the specified submodule's
# branch. All other tags will be ignored.
for submodule_tag in $(git tag --list --merged "${sub}/${branch}")
do
git merge -s ours -m "Merge submodule tag ${submodule_tag} for ${sub}/${branch}" ${ALLOW_UNRELATED_HISTORIES} "${submodule_tag}"
done
# Now merge actual files
git merge -s ours --no-commit ${ALLOW_UNRELATED_HISTORIES} "${sub}/${branch}"
rm -rf tmpdir
# Add submodule content
git clone -b "${branch}" "${url}" "${path}"
# Transfer its own submodules to the parent
add_submod_cmds=""
if [ -f ${path}/.gitmodules ]; then
sub_names=$(git config -f ${path}/.gitmodules --get-regex path | sed 's/.* \(.*\)$/\1/g' || true)
for sub_name in ${sub_names}; do
sub_branch=$(git config -f ${path}/.gitmodules --get "submodule.${sub_name}.branch") || true
[ -n "${sub_branch}" ] && sub_branch="-b ${sub_branch}"
sub_path=$(git config -f ${path}/.gitmodules --get "submodule.${sub_name}.path")
sub_url=$(git config -f ${path}/.gitmodules --get "submodule.${sub_name}.url")
# remove the sub-submodule (which should be empty) and cache the command to reinstate it
rmdir ${path}/${sub_path}
add_submod_cmds="$add_submod_cmds git submodule add ${sub_branch} --name ${sub_name} -- ${sub_url} ${path}/${sub_path} ; "
done
fi
rm -rf "${path}/.git" "${path}/.gitmodules"
git add "${path}"
if [ -n "${add_submod_cmds}" ]; then
bash -c "${add_submod_cmds}"
fi
git commit -m "Merge submodule contents for ${sub}/${branch}"
git config -f .git/config --remove-section "remote.${sub}"
set +x
echo "$(tput setaf 2)Submodule merge complete. Push changes after review.$(tput sgr0)"
}
set -euo pipefail
declare verbose=false
declare skip_warn=false
while [ $# -gt 0 ]; do
case "$1" in
(-h|--help)
usage
exit 0
;;
(-v|--verbose)
verbose=true
;;
(-f|--force)
skip_warn=true
;;
(*)
break
;;
esac
shift
done
declare sub="${1:-}"
declare branch="${2:-master}"
if [ -z "${sub}" ]; then
>&2 echo "Error: No submodule specified"
usage
exit 1
fi
shift
if [ -n "${1:-}" ]; then
shift
fi
if [ -n "${1:-}" ]; then
>&2 echo "Error: Unknown option: ${1:-}"
usage
exit 1
fi
if ! [ -d ".git" ]; then
>&2 echo "Error: No git repository found. Must be run from the root of a git repository"
usage
exit 1
fi
declare path="$(git config -f .gitmodules --get "submodule.${sub}.path")"
declare superproject_dir="$(dirname $(git config --get remote.origin.url))"
declare url=$(absolute_url $(git config -f .gitmodules --get "submodule.${sub}.url") $superproject_dir)
if [ -z "${path}" ]; then
>&2 echo "Error: Submodule not found: ${sub}"
usage
exit 1
fi
if [ -z "${superproject_dir}" ]; then
>&2 echo "Error: Could not determine the remote origin for this superproject: ${superproject_dir}"
usage
exit 1
fi
if ! [ -d "${path}" ]; then
>&2 echo "Error: Submodule path not found: ${path}"
usage
exit 1
fi
main
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