script: Add commit message check hook

script/commit-msg.go

@@ -0,0 +1,53 @@
+// Copyright (C) 2016 The Syncthing Authors.
+//
+// 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/.
+
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+)
+
+const (
+	exitSuccess = 0
+	exitError   = 1
+)
+
+var subject = regexp.MustCompile(`^[\w/,\. ]+: \w`)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Printf("Usage: %s <file>\n", filepath.Base(os.Args[0]))
+		os.Exit(exitError)
+	}
+
+	bs, err := ioutil.ReadFile(os.Args[1])
+	if err != nil {
+		fmt.Println("Reading input:", err)
+		os.Exit(exitError)
+	}
+
+	lines := bytes.Split(bs, []byte{'\n'})
+	if !subject.Match(lines[0]) {
+		fmt.Printf(`Commit message subject:
+    %s
+
+doesn't look like "tag: One sentence description". Specifically, it doesn't
+match this pattern:
+
+    %s
+`, lines[0], subject)
+		os.Exit(exitError)
+	}
+
+	os.Exit(exitSuccess)
+}