Commit b7c22b8f authored by Michał Kępień's avatar Michał Kępień
Browse files

Merge branch '98-add-util-git-replay-merge.sh' into 'master'

Put git-replay-merge in source tree

Closes #98

See merge request !83
parents 8282fd8b f7fe1e30
Pipeline #422 passed with stages
in 12 minutes and 16 seconds
#!/bin/bash
#
# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.
set -e
SELF="$(basename $0)"
SELF="${SELF/-/ }"
STATE_FILE=".git/REPLAY_MERGE"
die() {
for MESSAGE in "$@"; do
echo -e "${MESSAGE}" >&2
done
exit 1
}
die_with_usage() {
die "Usage:" \
"" \
" ${SELF} <merge_commit_id> <target_remote> <target_branch>" \
" ${SELF} --continue" \
" ${SELF} --abort"
}
die_with_continue_instructions() {
die "" \
"Replay interrupted. Conflicts need to be fixed manually." \
"When done, run \"${SELF} --continue\"." \
"Use \"${SELF} --abort\" to abort the replay."
}
die_if_wrong_dir() {
if [[ ! -d ".git" ]]; then
die "You need to run this command from the toplevel of the working tree."
fi
}
die_if_not_in_progress() {
die_if_wrong_dir
if [[ ! -f "${STATE_FILE}" ]]; then
die "No replay-merge in progress?"
fi
}
die_if_in_progress() {
die_if_wrong_dir
if [[ -f "${STATE_FILE}" ]]; then
die "Another replay-merge in progress. Use --continue or --abort."
fi
}
die_if_local_behind_target() {
TARGET_REF_HEAD="$(git rev-list --max-count=1 "${TARGET_REF}")"
if [[ "$(git merge-base "${TARGET_REF}" "${TARGET_BRANCH}")" != "${TARGET_REF_HEAD}" ]]; then
die "Local branch ${TARGET_BRANCH} is behind ${TARGET_REF}, cannot merge into it." \
"Update or remove the local branch, then run \"${SELF} --continue\"." \
"Use \"${SELF} --abort\" to abort the replay."
fi
}
branch_exists() {
ESCAPED_BRANCH_NAME=${1//\//\\\/}
BRANCH_REGEX="/^(remotes\/)?${ESCAPED_BRANCH_NAME}$/"
if [[ -n "$(git branch -a | awk "\$NF ~ ${BRANCH_REGEX} {print \$NF}")" ]]; then
return 0
else
return 1
fi
}
go() {
# Process parameters.
SOURCE_COMMIT="$1"
TARGET_REMOTE="$2"
TARGET_BRANCH="$3"
TARGET_REF="${TARGET_REMOTE}/${TARGET_BRANCH}"
# Establish the range of commits comprising the source branch.
REPLAY_COMMIT_RANGE="$(
git show --format="%P" "${SOURCE_COMMIT}" 2>&1 |
sed -n "1s/\([0-9a-f]\{40\}\) \([0-9a-f]\{40\}\)/\1..\2/p;"
)"
if [[ -z "${REPLAY_COMMIT_RANGE}" ]]; then
die "${SOURCE_COMMIT} is not a valid merge commit ID."
fi
# Extract the name of the source branch.
SOURCE_BRANCH="$(
git log --max-count=1 --format="%B" "${SOURCE_COMMIT}" |
sed -n "s/^Merge branch '\([^'][^']*\).*/\1/p;" |
head -n 1
)"
if [[ -z "${SOURCE_BRANCH}" ]]; then
die "Unable to extract source branch name from ${SOURCE_COMMIT}."
fi
# Ensure the target ref is valid.
if ! branch_exists "${TARGET_REF}"; then
die "${TARGET_REF} is not a valid replay target."
fi
# Abort if a local branch with the name about to be used for replaying
# the merge already exists.
REPLAY_BRANCH="${SOURCE_BRANCH}-${TARGET_BRANCH}"
if branch_exists "${REPLAY_BRANCH}"; then
die "Local branch with name ${REPLAY_BRANCH} already exists." \
"Cannot use it for replaying a merge."
fi
# Get the name of the currently checked out branch so that it can be
# checked out again once the replay is finished.
CHECKED_OUT_BRANCH="$(git branch | awk "\$1 == \"*\" {print \$2}")"
# Store state in case it needs to be restored later.
cat <<-EOF > "${STATE_FILE}"
CHECKED_OUT_BRANCH="${CHECKED_OUT_BRANCH}"
SOURCE_COMMIT="${SOURCE_COMMIT}"
SOURCE_BRANCH="${SOURCE_BRANCH}"
REPLAY_BRANCH="${REPLAY_BRANCH}"
TARGET_REMOTE="${TARGET_REMOTE}"
TARGET_BRANCH="${TARGET_BRANCH}"
TARGET_REF="${TARGET_REF}"
EOF
# Announce the plan.
echo "Attempting to replay ${REPLAY_COMMIT_RANGE} on top of ${TARGET_REF} in ${REPLAY_BRANCH}..."
# Switch to the replay branch.
git checkout -t -b "${REPLAY_BRANCH}" "${TARGET_REF}" >/dev/null
# Try replaying the branch. If there is any conflict, the command will
# fail, which means we need to bail and let the user fix the current
# cherry-pick manually, expecting "git replay-merge --continue" to be
# used afterwards. If there is no conflict, just proceed with what
# --continue would do.
if ! git cherry-pick -x "${REPLAY_COMMIT_RANGE}"; then
die_with_continue_instructions
fi
resume
}
resume() {
# If cherry-picking has not yet been completed, resume it. If it
# fails, bail. If if succeeds, we can proceed with merging.
if [[ -f ".git/sequencer/todo" ]]; then
if ! git cherry-pick --continue; then
die_with_continue_instructions
fi
fi
# Announce the plan.
echo "Attempting to merge ${REPLAY_BRANCH} into ${TARGET_BRANCH}..."
# Check if a local branch with the same name as the target branch
# exists. If it does not, switch to a new local branch with the same
# name as the target branch. Otherwise, ensure the local branch is not
# behind the target branch at the target remote, then switch to it.
if ! branch_exists "${TARGET_BRANCH}"; then
git checkout -t -b "${TARGET_BRANCH}" "${TARGET_REF}" >/dev/null
else
die_if_local_behind_target
git checkout "${TARGET_BRANCH}" &>/dev/null
fi
# Use the original commit message with a modified subject line.
COMMIT_MSG="$(
git log --max-count=1 --format="%B" "${SOURCE_COMMIT}" |
sed "1s/.*/Merge branch '${REPLAY_BRANCH}' into '${TARGET_BRANCH}'/;"
)"
# Merge the replay branch into the local target branch.
git merge --no-ff -m "${COMMIT_MSG}" "${REPLAY_BRANCH}"
cat <<-EOF
Replayed ${SOURCE_BRANCH} onto ${TARGET_BRANCH}.
To push the replay, use:
git push ${TARGET_REMOTE} ${TARGET_BRANCH}:${TARGET_BRANCH}
EOF
cleanup
}
cleanup() {
# Restore working copy state from before the replay was started,
# ignoring any potential errors to prevent "set -e" from interfering.
{
git merge --abort
git cherry-pick --abort
git checkout "${CHECKED_OUT_BRANCH}"
git branch -D "${REPLAY_BRANCH}"
} &>/dev/null || true
rm -f "${STATE_FILE}"
}
case "$1" in
"--abort")
die_if_not_in_progress
source "${STATE_FILE}"
cleanup
;;
"--continue")
die_if_not_in_progress
source "${STATE_FILE}"
resume
;;
*)
if [[ $# -ne 3 ]]; then
die_with_usage
fi
die_if_in_progress
go "$@"
;;
esac
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