scripts: update_ngtcp2.sh for semi-automatic embedded libngtcp2 updates

scripts/update_ngtcp2.sh

+#!/bin/bash
+
+set -ueo pipefail
+
+ROOT_PATH="$(dirname "$(realpath "$0")")/../src/contrib/libngtcp2/ngtcp2"
+NGTCP2_GIT="https://github.com/ngtcp2/ngtcp2"
+
+if [ $# != 1 ]; then
+	printf 'expected single arg - git tag name to which to upgrade\n'
+	exit 1
+fi
+
+clonedir="$(mktemp -d)"
+trap 'rm -rf "$clonedir"; printf "error encountered - aborting\n"' ERR
+
+cur_version=v"$(sed -En 's/^.*NGTCP2_VERSION[^"]*"([0-9.]+)"/\1/p' "${ROOT_PATH}/version.h")"
+
+git clone --branch="$1" "$NGTCP2_GIT" "${clonedir}/ngtcp2" 2>/dev/null
+
+cd "${clonedir}/ngtcp2"
+git diff --name-only --diff-filter=A "$cur_version" "$1"  | xargs -r realpath >../added
+git diff --name-only --diff-filter=D "$cur_version" "$1"  | xargs -r realpath >../deleted
+git diff --name-only --diff-filter=ad "$cur_version" "$1" | xargs -r realpath >../changed
+
+# generate new version.h
+autoreconf -if >/dev/null 2>&1
+./configure --enable-lib-only --with-gnutls >/dev/null 2>&1
+cp ./lib/includes/ngtcp2/version.h "${ROOT_PATH}"
+
+cd "$ROOT_PATH"
+
+# delete files deleted in new version
+while IFS=$'\n' read -r line; do
+	find . -type f -name "$(basename "$line")" | xargs -r rm
+done <"${clonedir}/deleted"
+
+# update changed files
+find . -type f | while IFS=$'\n' read -r line; do
+	base="$(basename "$line")"
+	match="$(grep -m1 "$base" "${clonedir}/changed" || true)"
+	if [ -n "$match" ]; then
+		cp "$match" "$line"
+	fi
+done
+
+# ngtcp2_crypto.h is the only non-unique filename, so we deal with it separately
+# ugly - I'm aware ;p
+cp "${clonedir}/ngtcp2/lib/ngtcp2_crypto.h" ./lib/ngtcp2_crypto.h
+cp "${clonedir}/ngtcp2/crypto/includes/ngtcp2/ngtcp2_crypto.h" ./ngtcp2_crypto.h
+
+newfiles="$(wc -l "${clonedir}/added" | cut -d' ' -f1)"
+if [ "$newfiles" -gt 0 ]; then
+	printf "%s new file(s) were added between %s and %s; add these manually if desired:\n" \
+		"$newfiles" "$cur_version" "$1"
+	cut -d'/' -f'5-' "${clonedir}/added" | xargs -r printf "\t%s\n"
+fi
+
+rm -rf "$clonedir"