res/ci/commit-lint.sh: add commit lint script

Author: classabbyamp

res/ci/commit-lint.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+die() {
+	printf '%s\n' "$*" >&2
+	exit 1
+}
+
+command -v git >/dev/null 2>&1 ||
+die "neither chroot-git nor git could be found!"
+
+tip="$(git rev-list -1 --parents HEAD)"
+case "$tip" in
+	# This is a merge commit, pick last parent
+	*" "*" "*) tip="${tip##* }" ;;
+	# This is a non-merge commit, pick itself
+	*)         tip="${tip%% *}" ;;
+esac
+
+base="$(git merge-base origin/HEAD "$tip")"
+
+[ $(git rev-list --count "$tip" "^$base") -lt 20 ] || {
+	echo "::error title=Branch out of date::Your branch is too out of date. Please rebase on upstream and force-push."
+	exit 1
+}
+
+status=0
+
+for cmt in $(git rev-list --abbrev-commit $base..$tip)
+do
+    git cat-file commit "$cmt" |
+    awk -vC="$cmt" '
+    # skip header
+    /^$/ && !msg { msg = 1; next }
+    !msg { next }
+    # 3: long-line-is-banned-except-footnote-like-this-for-url
+    (NF > 2) && (length > 80) { print "::error title=Commit Lint::" C ": long line: " $0; exit 1 }
+    !subject {
+        if (length > 50) { print "::warning title=Commit Lint::" C ": subject is a bit long" }
+        if (!($0 ~ ":")) { print "::error title=Commit Lint::" C ": subject does not follow CONTRIBUTING.md guidelines"; exit 1 }
+        subject = 1; next
+    }
+    /^$/ { body = 1; next }
+    !body { print "::error title=Commit Lint::" C ": second line must be blank"; exit 1 }
+    ' || status=1
+done
+exit $status