cvs2git

#!/bin/mksh
# -*- mode: sh -*-
#-
# Copyright © 2014, 2015, 2017, 2020
#	mirabilos <m@mirbsd.org>
#
# Provided that these terms and disclaimer and all copyright notices
# are retained or reproduced in an accompanying document, permission
# is granted to deal in this work without restriction, including un‐
# limited rights to use, publicly perform, distribute, sell, modify,
# merge, give away, or sublicence.
#
# This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
# the utmost extent permitted by applicable law, neither express nor
# implied; without malicious intent or gross negligence. In no event
# may a licensor, author or contributor be held liable for indirect,
# direct, other damage, loss, or other issues arising in any way out
# of dealing in the work, even if advised of the possibility of such
# damage or existence of a defect, except proven that it results out
# of said person’s immediate fault when using the work as intended.
#-
# Depends: cvs (>= 2:1.12.13+real-18), cvs2svn (>= 2.4.0-4)

# needs mksh R50 2014/06/10
set -o pipefail

mydir=$(dirname "$(realpath "$0")")
cfg=${1%%.cfg}.cfg
for tool in cvs cvs2git git; do
	var=$(whence -p $tool) && [[ -n $var && -x $var ]] && continue
	print -ru2 "E: tool $tool missing"
	exit 1
done

cd "$mydir"
if [[ -z $cfg || $cfg = */* || ! -s $cfg ]]; then
	print -ru2 "E: configuration file '$cfg' not found"
	exit 1
fi
set -A pprm_branches
set -A pprm_tags
set -A torm_branches
set -A torm_tags
set -A extra_grafts
set -A remote
unset domain source prepend cvs2git_username
do_precollect() { :; }
do_extrafetch() { :; }	# make this set do_grafts=1 if used
. "$mydir/$cfg"
for var in source remote; do
	eval '[[ -n $'$var' ]]' && continue
	print -ru2 "E: config file '$cfg' var $var not set"
	exit 1
done
if [[ ! -d $source/. ]]; then
	print -ru2 "E: config file '$cfg' source '$source' does not exist"
	exit 1
fi
[[ -n $cvs2git_username ]] || if [[ -n $domain ]]; then
	cvs2git_username=root
else
	cvs2git_username=cvs2git
fi

# not in /tmp due to sheer size of tmp files
if ! T=$(mktemp -d /var/tmp/cvs2git.XXXXXXXXXX); then
	print -u2 "E: mkdtemp failed"
	exit 255
fi
print -ru2 "I: Entering working area '$T'"
cd "$T"

function cleanup_and_die {
	cd /
	#print -ru2 \
	rm -rf "$T"
	exit ${1:-1}
}

trap cleanup_and_die 1 2 3 5 13 15

function die {
	print -ru2 "E: $*"
	cleanup_and_die
}

(do_precollect) || die do_precollect failed

cat >cvswrapper <<-EOF
	#!/bin/mksh
	cvs "\$@" 2>${T@Q}/cvswrapped; rv=\$?
	grep -E -v \
	    -e 'Danger: Granting read access to incompatible repository!' \
	    -e 'CVSROOT/config: found keyword .(tag|umask|DisableXProg). in repository' \
	    <${T@Q}/cvswrapped >&2
	exit \$rv
EOF
chmod +x cvswrapper || die "chmod failed with errorlevel $?"
print -u2 "I: $SECONDS seconds elapsed for setup"

cvs2git --blobfile=blobfile --dumpfile=dumpfile \
    --encoding=utf-8 --fallback-encoding=cp1252 \
    --username="$cvs2git_username" --keywords-off --keep-cvsignore \
    --use-cvs --cvs="$T"/cvswrapper \
    --force-keyword-mode=kept ${domain:+--cvs-domain="$domain"} \
    "$source" || die "cvs2git failed with errorlevel $?"
print -u2 "I: $SECONDS seconds elapsed for cvs2git"

git='git -c advice.graftFileDeprecated=false'
$git init --bare dst || die "git init failed with errorlevel $?"
cd dst
$git fast-import --export-marks=../cvs2git-tmp/git-marks.dat <../blobfile || \
    die "git fast-import of blobfile failed with errorlevel $?"
print -u2 "I: $SECONDS seconds elapsed for blob import"
$git fast-import --import-marks=../cvs2git-tmp/git-marks.dat <../dumpfile || \
    die "git fast-import of dumpfile failed with errorlevel $?"
print -u2 "I: $SECONDS seconds elapsed for dump import"

for rem in "${remote[@]}"; do
	[[ $rem = /* && ! -d $rem/. ]] || continue
	mkdir -p "$rem" || \
	    die "remote '$rem' not found and could not be created (with errorlevel $?) either"
	$git init --bare "$rem" || die "git init '$rem' failed with errorlevel $?"
done
for var in "${torm_branches[@]}"; do
	$git branch -D "$var" || die "git branch failed with errorlevel $?"
done
for var in "${torm_tags[@]}"; do
	$git tag -d "$var" || die "git tag failed with errorlevel $?"
done
print -u2 "I: $SECONDS seconds elapsed for janitorial work"

do_grafts=0
if [[ -n $prepend ]]; then
	# Urahn means ancestor… it’s hard to find terms to use that
	# do not already have meaning in (D)VCS context…
	$git remote add urahn "$prepend" || \
	    die "git remote failed with errorlevel $?"
	# mixin tags
	$git ls-remote --tags urahn | while read -r hash ref; do
		if $git show-ref --verify --quiet "$ref"; then
			# tag already exists
			$git show-ref --verify "$ref" |&
			read -pr exhash exref
			print -ru2 "I: pull existing tag '$ref' ($hash vs $exhash)"
			if [[ $hash = "$exhash" ]]; then
				# they are the same, though, uniquify
				continue
			fi
			# rename older tag, at most once
			new=$ref@$hash
			if $git show-ref --verify --quiet "$new"; then
				# renamed tag also already exists
				$git show-ref --verify "$new" |&
				read -pr exhash exref
				[[ $hash = "$exhash" ]] && continue
				die "new ref '$new' already exists"
			fi
		else
			# fetch the existing tag
			print -ru2 "I: pull new tag '$ref' ($hash)"
			new=$ref
		fi
		$git fetch -n urahn "$ref:$new" || \
		    die "git fetch failed with errorlevel $?"
	done || die "git ls-remote failed with errorlevel $?"
	# mixin branches
	$git ls-remote --heads urahn | while read -r hash ref; do
		if ! $git show-ref --verify --quiet "$ref"; then
			# branch does not yet exist, simply pull it
			print -ru2 "I: pull new branch '$ref' ($hash)"
			$git fetch -n urahn "$ref:$ref" || \
			    die "git fetch failed with errorlevel $?"
			continue
		fi
		print -ru2 "I: pull existing branch '$ref'"
		# fetch objects belonging to the branch (old)
		$git fetch -n urahn "$ref" || \
		    die "git fetch failed with errorlevel $?"
		# find out the root commit of the branch (new)
		exhash=$($git rev-list "$ref" | tail -n 1) || \
		    die "git rev-list | tail failed with errorlevel $?"
		# create a graft point
		print -r -- "$exhash" "$hash" >>info/grafts
		print -ru2 "N: graft $exhash $hash"
	done || die "git ls-remote failed with errorlevel $?"
	# remove branches/tags that are not necessary to merge
	for var in "${pprm_branches[@]}"; do
		$git branch -D "$var" || die "git branch failed with errorlevel $?"
	done
	for var in "${pprm_tags[@]}"; do
		$git tag -d "$var" || die "git tag failed with errorlevel $?"
	done
	do_grafts=1
fi
do_extrafetch
if (( do_grafts )); then
	for var in "${extra_grafts[@]}"; do
		print -r -- $var >>info/grafts
		print -ru2 "N: extra graft" $var
	done
	if [[ -n $cvs2git_graft_debugging ]]; then
		print -ru2 "!! Spawning a shell for graft debugging"
		print -ru2 "N: Type 'exit' to continue conversion!"
		mksh -l 0<>/dev/tty >&0 2>&0
	fi
	# drop extra remotes before doing this, for speed
	for var in $($git remote); do
		$git remote remove "$var" || \
		    die "git remote failed with errorlevel $?"
	done
	# make graft permanent
	if [[ -s info/grafts ]]; then
		FILTER_BRANCH_SQUELCH_WARNING=1 \
		$git filter-branch --tag-name-filter cat -- --all || \
		    die "git filter-branch failed with errorlevel $?"
		rm -f info/grafts
	fi
	# nuke junk
	$git for-each-ref --format="%(refname)" refs/original/ | \
	    while IFS= read -r ref; do
		$git update-ref -d "$ref" || \
		    die "git update-ref failed with errorlevel $?"
	done || die "git for-each-ref failed with errorlevel $?"
	print -u2 "I: $SECONDS seconds elapsed for history prepending"
fi

$git reflog expire --expire=all --all || die "git reflog failed with errorlevel $?"
$git gc --aggressive --prune=now || die "git gc failed with errorlevel $?"
print -u2 "I: $SECONDS seconds elapsed for garbage collection"
for rem in "${remote[@]}"; do
	print -ru2 "D: pushing to $rem"
	$git remote add target "$rem" || die "git remote failed with errorlevel $?"
	$git push --mirror target || die "git push failed with errorlevel $?"
	$git remote remove target || die "git remote failed with errorlevel $?"
done
print -u2 "I: $SECONDS seconds elapsed after pushing"
for rem in "${remote[@]}"; do
	[[ $rem = /* ]] || continue
	print -ru2 "D: gc’ing $rem"
	cd "$rem" && $git gc
done
print -u2 "I: $SECONDS seconds elapsed after gc’ing"

cd /
rm -rf "$T"
exit 0