Add stwatchfile

cmd/stwatchfile/main.go

@@ -0,0 +1,98 @@
+// Copyright (C) 2015 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/.
+
+package main
+
+import (
+	"bytes"
+	"crypto/md5"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"time"
+)
+
+func getmd5(filePath string) ([]byte, error) {
+	var result []byte
+	file, err := os.Open(filePath)
+	if err != nil {
+		return result, err
+	}
+	defer file.Close()
+
+	hash := md5.New()
+	if _, err := io.Copy(hash, file); err != nil {
+		return result, err
+	}
+
+	return hash.Sum(result), nil
+}
+
+func main() {
+	period := flag.Duration("period", 200*time.Millisecond, "Sleep period between checks")
+	flag.Parse()
+
+	file := flag.Arg(0)
+
+	if file == "" {
+		fmt.Println("Expects a path as an argument")
+		return
+	}
+
+	exists := true
+	size := int64(0)
+	mtime := time.Time{}
+	hash := []byte{}
+
+	for {
+		time.Sleep(*period)
+
+		newExists := true
+		fi, err := os.Stat(file)
+		if err != nil && os.IsNotExist(err) {
+			newExists = false
+		} else if err != nil {
+			fmt.Println("stat:", err)
+			return
+		}
+
+		if newExists != exists {
+			exists = newExists
+			if !newExists {
+				fmt.Println(file, "does not exist")
+			} else {
+				fmt.Println(file, "appeared")
+			}
+		}
+
+		if !exists {
+			size = 0
+			mtime = time.Time{}
+			hash = []byte{}
+			continue
+		}
+
+		if fi.IsDir() {
+			fmt.Println(file, "is directory")
+			return
+		}
+		newSize := fi.Size()
+		newMtime := fi.ModTime()
+
+		newHash, err := getmd5(file)
+		if err != nil {
+			fmt.Println("getmd5:", err)
+		}
+
+		if newSize != size || newMtime != mtime || !bytes.Equal(newHash, hash) {
+			fmt.Println(file, "Size:", newSize, "Mtime:", newMtime, "Hash:", fmt.Sprintf("%x", newHash))
+			hash = newHash
+			size = newSize
+			mtime = newMtime
+		}
+	}
+}