httpfs.go

// httpfs Performs GET requests when reading a file.
// Compile with `go build httpfs.go` and then run with `./httpfs /http`,
// then try doing `cat /http/aduffy.org`
package main

import (
	"flag"
	"io/ioutil"
	"log"
	"net/http"
	"os"

	"bazil.org/fuse"
	"bazil.org/fuse/fs"
	"golang.org/x/net/context"
)

func main() {
	flag.Parse()

	if flag.NArg() != 1 {
		flag.Usage()
		os.Exit(2)
	}
	mountpoint := flag.Arg(0)

	c, err := fuse.Mount(
		mountpoint,
		fuse.FSName("http"),
		fuse.Subtype("httpfs"),
		fuse.LocalVolume(),
		fuse.VolumeName("httpfs"),
	)
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()

	err = fs.Serve(c, FS{})
	if err != nil {
		log.Fatal(err)
	}

	// check if the mount process has an error to report
	<-c.Ready
	if err := c.MountError; err != nil {
		log.Fatal(err)
	}
}

// FS implements the hello world file system.
type FS struct{}

func (FS) Root() (fs.Node, error) {
	return Dir{}, nil
}

// Dir implements both Node and Handle for the root directory.
type Dir struct{}

func (Dir) Attr(ctx context.Context, a *fuse.Attr) error {
	a.Inode = 1
	a.Mode = os.ModeDir | 0555
	return nil
}

func (Dir) Lookup(ctx context.Context, name string) (fs.Node, error) {
	return File{"http://" + name}, nil
}

var dirDirs = []fuse.Dirent{
//	{Inode: 2, Name: "hello", Type: fuse.DT_File},
}

func (Dir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
	return dirDirs, nil
}

// File implements both Node and Handle for the hello file.
type File struct {
	Url string // The URL we are looking up
}

func (f File) Attr(ctx context.Context, a *fuse.Attr) error {
	a.Inode = 2   // Every file is ephemeral anyway
	a.Mode = 0444 // Read only
	bytes, err := getRequest(f.Url)
	if err != nil {
		a.Size = 0
	} else {
		a.Size = uint64(len(bytes))
	}
	return nil
}

func (f File) ReadAll(ctx context.Context) ([]byte, error) {
	if body, err := getRequest(f.Url); err != nil {
		return nil, err
	} else {
		return body, nil
	}
}

func getRequest(url string) ([]byte, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	if body, err := ioutil.ReadAll(resp.Body); err != nil {
		return nil, err
	} else {
		return body, nil
	}
}