list files in a directory

scandir.go

// list files in a directory
// code adapted from github.com/replicon/fast-archiver

package main

import (
	"fmt"
	"log"
	"os"
	"io"
	"sync"
	"path/filepath"
	"time"
	"flag"
)

type MyScanner struct {
	Recursive bool

	dirChan chan string
	fileChan chan string
	syncWorker sync.WaitGroup
}

func (m *MyScanner) Run(path string) {
	t0 := time.Now()

	m.dirChan = make(chan string)
	m.fileChan = make(chan string)

	m.syncWorker.Add(1)

	go func(){ m.dirChan <- path }()

	go m.scanDir()

	go func(){
		m.syncWorker.Wait()
		close(m.dirChan)
		close(m.fileChan)
	}()


	total := 0
	for filename := range m.fileChan {
		fmt.Println(filename)
		total++
	}

	t1 := time.Now()
	fmt.Printf("%d files scanned in %v\n", total, t1.Sub(t0))
}

func (m *MyScanner) scanDir() {
	for path := range m.dirChan {
		dir, err := os.Open(path)
		if err != nil {
			log.Println("directory read error:", err)
			m.syncWorker.Done()
			continue
		}

		for fileName := range m.readdirnames(dir) {
			filePath := filepath.Join(path, fileName)

			fileInfo, err := os.Lstat(filePath)
			if err != nil {
				log.Println("unable to lstat file", err.Error())
				continue
			} else if (fileInfo.Mode() & os.ModeSymlink) != 0 {
				log.Println("skipping symbolic link", filePath)
				continue
			}

			if fileInfo.IsDir() && m.Recursive {
				m.syncWorker.Add(1)
				go func(filePath string) {
					m.dirChan <- filePath
				}(filePath)
			} else {
				m.fileChan <- filePath
			}
		}

		dir.Close()
		m.syncWorker.Done()
	}
}

func (m *MyScanner) readdirnames(dir *os.File) chan string {
	retval := make(chan string, 256)
	go func(dir *os.File) {
		for {
			names, err := dir.Readdirnames(256)
			if err == io.EOF {
				break
			} else if err != nil {
				log.Println("error reading directory:", err.Error())
			}
			for _, name := range names {
				retval <- name
			}
		}
		close(retval)
	}(dir)
	return retval
}

var baseDir = flag.String("p", "", "/path/to/the/directory")

func main() {
	flag.Parse()

	if *baseDir == "" {
		flag.PrintDefaults()
		os.Exit(1)
	}

	(&MyScanner{Recursive: true}).Run(*baseDir)
}