Meta: Add commit linting commit-hook

script/lint-commit.sh

@@ -0,0 +1,64 @@
+#!/bin/sh
+
+# Lint commit message
+# Depends: git
+
+# ------------------------------------------
+
+error() {
+	b="$(tput bold)"
+	red="$(tput setf 4)"
+	n="$(tput sgr0)"
+
+	echo "${b}${red}Error:${n} $1" >&2
+	exit 1
+}
+
+if [ ! -d ".git" ]; then
+	error "please run this script from the project root"
+fi
+
+# The file containing the commit message is passed as the first argument
+file="$1"
+message="$(cat "$file")"
+
+newline="$(printf '\x0D')"
+if grep -Uq "$newline" "$file"; then
+	error "commit message contains CRLF line breaks (only unix-style LF linebreaks are allowed)"
+fi
+
+lineNumber=0
+echo "$message" | while read -r line; do
+	lineNumber=$((lineNumber + 1))
+	lineLength=${#line}
+
+	# Ignore comment lines
+	if echo "$line" | awk '$0 !~ /^#.*/ { exit 1 }'; then continue; fi
+	# Ignore overlong 'fixup!' commit descriptions
+	if echo "$line" | awk '$0 !~ /^fixup! .*/ { exit 1 }'; then continue; fi
+
+	if [ "$lineNumber" -eq 2 ] && [ "$lineLength" -ne 0 ]; then
+		error "empty line between commit title and body is missing"
+	fi
+
+	categoryPattern="^\S.*?\S: .+"
+	if [ $lineNumber -eq 1 ] && (echo "$line" | grep -Evq "$categoryPattern"); then
+		error "missing category in commit title (if this is a fix up of a previous commit, it should be squashed)"
+	fi
+
+	titleCasePattern="^\S.*?: [A-Z0-9]"
+	if [ $lineNumber -eq 1 ] && (echo "$line" | grep -Evq "$titleCasePattern"); then
+		error "first word of commit after the subsystem is not capitalized"
+	fi
+
+	if [ $lineNumber -eq 1 ] && (echo "$line" | awk '$0 !~ /\.$/ { exit 1 }' ); then
+		error "commit title ends in a period"
+	fi
+
+	urlPattern="([a-z]+:\/\/)?(([a-zA-Z0-9_]|-)+\.)+[a-z]{2,}(:\d+)?([a-zA-Z_0-9@:%\+.~\?&\/=]|-)+"
+	if [ "$lineLength" -gt 72 ] && (echo "$line" | grep -Evq "$urlPattern"); then
+		error "commit message lines are too long (maximum allowed is 72 characters)"
+	fi
+done
+
+exit 0

script/pre-commit.sh

@@ -40,33 +40,37 @@ fi
 # Get the path from the project root to the script
 subDir="$(dirname -- "$0")"
 
-hooks="
-lint-ci.sh
-"
+create() {
+	file="$1"
+	if ! test -f "$file"; then
+		touch "$file"
+		chmod +x "$file"
+		echo "#!/bin/sh" > "$file"
+	fi
+}
 
 install() {
-	echo "Installing pre-commit hooks"
+	echo "Installing commit hooks"
 
 	preCommit=".git/hooks/pre-commit"
-	if ! test -f "$preCommit"; then
-		touch "$preCommit"
-		chmod +x "$preCommit"
-		echo "#!/bin/sh" > "$preCommit"
-	fi
-
-	for hook in $hooks; do
-		sed -Ei "/$hook/d" "$preCommit"
-		sed -Ei "\$ a $subDir/$hook" "$preCommit"
-	done
+	create "$preCommit"
+	sed -Ei "/lint-ci.sh/d" "$preCommit"
+	sed -Ei "\$ a $subDir/lint-ci.sh" "$preCommit"
+
+	commitMsg=".git/hooks/commit-msg"
+	create "$commitMsg"
+	sed -Ei "/lint-commit.sh/d" "$commitMsg"
+	sed -Ei "\$ a $subDir/lint-commit.sh" "$commitMsg"
 }
 
 remove() {
-	echo "Removing pre-commit hooks"
+	echo "Removing commit hooks"
 
 	preCommit=".git/hooks/pre-commit"
-	for hook in $hooks; do
-		sed -Ei "/$hook/d" "$preCommit"
-	done
+	sed -Ei "/lint-ci.sh/d" "$preCommit"
+
+	commitMsg=".git/hooks/commit-msg"
+	sed -Ei "/lint-commit.sh/d" "$commitMsg"
 }
 
 # Command handling