golang 生成目录的check list文件并校验目录

目的是将当前可执行程序平级的某个目录生成check list文件，表明是文件还是目录，如果是文件生成md5值。还可以根据check list文件来判断目录里面的内容是否完整，如果是目录就判断目录是否存在，如果是文件就比对md5值是否一样。

生成check list 文件：

checkfilelist.exe -name app -mode write

校验目录是否完整：

checkfilelist.exe -name app -mode check

代码如下：

package main

import (
	"bufio"
	"crypto/md5"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"os"
	"os/exec"
	"path"
	"path/filepath"
)

const CHECKLISTNAME = "checklist.json"

type DirCheck struct {
	Name  string `json:"name"`
	Items []Item
}

type Item struct {
	Type int    `json:"type"`
	Path string `json:"path"`
	Md5  string `json:"md5"`
}

func main() {
	var dirname string
	var mode string
	flag.StringVar(&dirname, "name", "", "directory name")
	flag.StringVar(&mode, "mode", "", "write or check")
	flag.Parse()

	currentfile, _ := exec.LookPath(os.Args[0])
	currentpath, _ := filepath.Abs(currentfile)
	currentdir := path.Join(currentpath, "..")
	fmt.Println("src dir:", currentdir, "name:", dirname)
	if mode == "write" {
		Write(currentdir, dirname)
		fmt.Println("write success")
	} else if mode == "check" {
		err := Check(currentdir, CHECKLISTNAME)
		if err != nil {
			panic(err)
		} else {
			fmt.Println("check success")
		}
	} else {
		panic("mode error")
	}
}

func Write(currentdir string, dirname string) {
	srcdir := path.Join(currentdir, dirname)
	fmt.Println("src dir:", srcdir)
	dc := DirCheck{}
	dc.Name = filepath.Base(srcdir)
	filepath.WalkDir(srcdir, func(pathstr string, d fs.DirEntry, err error) error {
		abspath := pathstr[len(srcdir):]
		if len(abspath) == 0 {
			return nil
		}

		filetype := 0
		md5str := ""
		if d.IsDir() {
			filetype = 1
		} else {
			filetype = 2
			md5str, err = MD5File(pathstr)
			if err != nil {
				fmt.Println("md5 error, path:", pathstr)
				panic(err)
			}
		}

		dc.Items = append(dc.Items, Item{
			Type: filetype,
			Path: abspath,
			Md5:  md5str,
		})
		fmt.Println(abspath)
		return nil
	})

	b, err := json.MarshalIndent(dc, "", "  ")
	if err != nil {
		panic(err)
	}

	if err := os.WriteFile(CHECKLISTNAME, b, os.ModePerm); err != nil {
		panic(err)
	}
}

func Check(currentdir string, name string) error {
	checklistpath := path.Join(currentdir, name)
	b, err := os.ReadFile(checklistpath)
	if err != nil {
		return err
	}

	var dc DirCheck
	if err := json.Unmarshal(b, &dc); err != nil {
		return err
	}

	for _, item := range dc.Items {
		pathstr := path.Join(currentdir, dc.Name, item.Path)
		if item.Type == 1 {
			if !FileExists(pathstr) {
				return fmt.Errorf("directory not found, dir:%s", pathstr)
			}
		} else if item.Type == 2 {
			md5str, err := MD5File(pathstr)
			if err != nil {
				return err
			}
			if md5str != item.Md5 {
				return fmt.Errorf("md5 not match, path:%s", pathstr)
			}
		}
	}
	return nil
}

func MD5File(file string) (string, error) {
	f, err := os.Open(file)
	if err != nil {
		return "", err
	}
	defer f.Close()

	r := bufio.NewReader(f)
	h := md5.New()
	_, err = io.Copy(h, r)
	if err != nil {
		return "", err
	}

	return fmt.Sprintf("%X", h.Sum(nil)), nil
}

func FileExists(path string) bool {
	_, err := os.Stat(path)
	if err != nil {
		if os.IsExist(err) {
			return true
		}
		return false
	}
	return true
}