cmd/httpdfs: implement [libhttp.Server] with [memfs.MemFS]

The httpdfs accept single directory to be served under HTTP server,
with the following options,

  -address <IP:PORT>
	Run the HTTP server on specific IP address and port.
    	Default to ` + defAddress + `.

  -exclude <regex>
	Exclude the files matched by regex from being served.
	Default to empty, none of files is excluded.

  -help
	Print this usage.

  -include <regex>
	Serve only list of files matched with regex.
	Default to include CSS, HTML, JavaScript, ICO, JPG, PNG, and
	SVG files only.

  -version
	Print the program version.

2 files changed, 148 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 9c0cad59..cc0c8329 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,7 @@
 /_bin/epoch
 /_bin/gofmtcomment
 /_bin/hexo
+/_bin/httpdfs
 /_bin/ini
 /_bin/sendemail
 /_bin/smtpcli
diff --git a/cmd/httpdfs/main.go b/cmd/httpdfs/main.go
new file mode 100644
index 00000000..62f0c32b
--- /dev/null
+++ b/cmd/httpdfs/main.go
@@ -0,0 +1,147 @@
+// Copyright 2023, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Program httpdfs implement [libhttp.Server] with [memfs.MemFS].
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+
+	"github.com/shuLhan/share"
+	libhttp "github.com/shuLhan/share/lib/http"
+	"github.com/shuLhan/share/lib/memfs"
+)
+
+const (
+	defAddress = `127.0.0.1:28194`
+	defInclude = `.*\.(css|html|ico|js|jpg|png|svg)$`
+)
+
+func main() {
+	var (
+		flagAddress string
+		flagExclude string
+		flagInclude string
+
+		flagHelp    bool
+		flagVersion bool
+	)
+
+	flag.StringVar(&flagAddress, `address`, defAddress, `Listen address`)
+	flag.StringVar(&flagExclude, `exclude`, ``, `Regex to exclude files in base directory`)
+	flag.BoolVar(&flagHelp, `help`, false, `Print the command usage`)
+	flag.StringVar(&flagInclude, `include`, defInclude, `Regex to include files in base directory`)
+	flag.BoolVar(&flagVersion, `version`, false, `Print the program version`)
+
+	flag.Parse()
+
+	var cmdName = os.Args[0]
+
+	if flagHelp {
+		usage(cmdName)
+		os.Exit(0)
+	}
+	if flagVersion {
+		fmt.Println(share.Version)
+		os.Exit(0)
+	}
+
+	var (
+		dirBase = flag.Arg(0)
+		err     error
+	)
+	if len(dirBase) == 0 {
+		dirBase, err = os.Getwd()
+		if err != nil {
+			log.Fatalf(`%s: %s`, cmdName, err)
+		}
+	}
+
+	var (
+		mfsOpts = memfs.Options{
+			Root:        dirBase,
+			Includes:    []string{flagInclude},
+			MaxFileSize: -1,
+			TryDirect:   true,
+		}
+		mfs *memfs.MemFS
+	)
+	if len(flagExclude) != 0 {
+		mfsOpts.Excludes = []string{flagExclude}
+	}
+
+	mfs, err = memfs.New(&mfsOpts)
+	if err != nil {
+		log.Fatalf(`%s: %s`, cmdName, err)
+	}
+
+	var (
+		serverOpts = libhttp.ServerOptions{
+			Memfs:           mfs,
+			Address:         flagAddress,
+			EnableIndexHtml: true,
+		}
+		httpd *libhttp.Server
+	)
+
+	httpd, err = libhttp.NewServer(&serverOpts)
+	if err != nil {
+		log.Fatalf(`%s: %s`, cmdName, err)
+	}
+
+	var signalq = make(chan os.Signal, 1)
+	signal.Notify(signalq, os.Interrupt, os.Kill)
+
+	go func() {
+		log.Printf(`%s: serving %q at http://%s`, cmdName, dirBase, flagAddress)
+		var errStart = httpd.Start()
+		if errStart != nil {
+			log.Printf(`%s: %s`, cmdName, errStart)
+		}
+	}()
+
+	<-signalq
+
+	err = httpd.Stop(0)
+	if err != nil {
+		log.Printf(`%s: %s`, cmdName, err)
+	}
+}
+
+func usage(cmdName string) {
+	fmt.Println(`= ` + cmdName + ` - a simple HTTP server
+
+	` + cmdName + ` [options] <dir>
+
+== Options
+
+	-address <IP:PORT>
+		Run the HTTP server on specific IP address and port.
+		Default to ` + defAddress + `.
+
+	-exclude <regex>
+		Exclude the files matched by regex from being served.
+		Default to empty, none of files is excluded.
+
+	-help
+		Print this usage.
+
+	-include <regex>
+		Serve only list of files matched with regex.
+		Default to include CSS, HTML, JavaScript, ICO, JPG, PNG, and
+		SVG files only.
+
+	-version
+		Print the program version.
+
+== Parameter
+
+	<dir>
+		Directory to be served under HTTP.
+		If not set default to current directory.`)
+}