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path: root/swarm/fuse/swarmfs_unix.go
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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// +build linux darwin freebsd

package fuse

import (
    "bazil.org/fuse"
    "bazil.org/fuse/fs"
    "errors"
    "fmt"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/swarm/api"
    "os"
    "path/filepath"
    "strings"
    "sync"
    "time"
)

var (
    errEmptyMountPoint = errors.New("need non-empty mount point")
    errMaxMountCount   = errors.New("max FUSE mount count reached")
    errMountTimeout    = errors.New("mount timeout")
    errAlreadyMounted  = errors.New("mount point is already serving")
)

func isFUSEUnsupportedError(err error) bool {
    if perr, ok := err.(*os.PathError); ok {
        return perr.Op == "open" && perr.Path == "/dev/fuse"
    }
    return err == fuse.ErrOSXFUSENotFound
}

// information about every active mount
type MountInfo struct {
    MountPoint     string
    StartManifest  string
    LatestManifest string
    rootDir        *SwarmDir
    fuseConnection *fuse.Conn
    swarmApi       *api.Api
    lock           *sync.RWMutex
}

// Inode numbers need to be unique, they are used for caching inside fuse
func newInode() uint64 {
    inodeLock.Lock()
    defer inodeLock.Unlock()
    inode += 1
    return inode
}

func NewMountInfo(mhash, mpoint string, sapi *api.Api) *MountInfo {
    newMountInfo := &MountInfo{
        MountPoint:     mpoint,
        StartManifest:  mhash,
        LatestManifest: mhash,
        rootDir:        nil,
        fuseConnection: nil,
        swarmApi:       sapi,
        lock:           &sync.RWMutex{},
    }
    return newMountInfo
}

func (self *SwarmFS) Mount(mhash, mountpoint string) (*MountInfo, error) {

    if mountpoint == "" {
        return nil, errEmptyMountPoint
    }
    cleanedMountPoint, err := filepath.Abs(filepath.Clean(mountpoint))
    if err != nil {
        return nil, err
    }

    self.swarmFsLock.Lock()
    defer self.swarmFsLock.Unlock()

    noOfActiveMounts := len(self.activeMounts)
    if noOfActiveMounts >= maxFuseMounts {
        return nil, errMaxMountCount
    }

    if _, ok := self.activeMounts[cleanedMountPoint]; ok {
        return nil, errAlreadyMounted
    }

    log.Info(fmt.Sprintf("Attempting to mount %s ", cleanedMountPoint))
    key, manifestEntryMap, err := self.swarmApi.BuildDirectoryTree(mhash, true)
    if err != nil {
        return nil, err
    }

    mi := NewMountInfo(mhash, cleanedMountPoint, self.swarmApi)

    dirTree := map[string]*SwarmDir{}
    rootDir := NewSwarmDir("/", mi)
    dirTree["/"] = rootDir
    mi.rootDir = rootDir

    for suffix, entry := range manifestEntryMap {

        key = common.Hex2Bytes(entry.Hash)
        fullpath := "/" + suffix
        basepath := filepath.Dir(fullpath)

        parentDir := rootDir
        dirUntilNow := ""
        paths := strings.Split(basepath, "/")
        for i := range paths {
            if paths[i] != "" {
                thisDir := paths[i]
                dirUntilNow = dirUntilNow + "/" + thisDir

                if _, ok := dirTree[dirUntilNow]; !ok {
                    dirTree[dirUntilNow] = NewSwarmDir(dirUntilNow, mi)
                    parentDir.directories = append(parentDir.directories, dirTree[dirUntilNow])
                    parentDir = dirTree[dirUntilNow]

                } else {
                    parentDir = dirTree[dirUntilNow]
                }

            }
        }
        thisFile := NewSwarmFile(basepath, filepath.Base(fullpath), mi)
        thisFile.key = key

        parentDir.files = append(parentDir.files, thisFile)
    }

    fconn, err := fuse.Mount(cleanedMountPoint, fuse.FSName("swarmfs"), fuse.VolumeName(mhash))
    if isFUSEUnsupportedError(err) {
        log.Warn("Fuse not installed", "mountpoint", cleanedMountPoint, "err", err)
        return nil, err
    } else if err != nil {
        fuse.Unmount(cleanedMountPoint)
        log.Warn("Error mounting swarm manifest", "mountpoint", cleanedMountPoint, "err", err)
        return nil, err
    }
    mi.fuseConnection = fconn

    serverr := make(chan error, 1)
    go func() {
        log.Info(fmt.Sprintf("Serving %s at %s", mhash, cleanedMountPoint))
        filesys := &SwarmRoot{root: rootDir}
        if err := fs.Serve(fconn, filesys); err != nil {
            log.Warn(fmt.Sprintf("Could not Serve SwarmFileSystem error: %v", err))
            serverr <- err
        }

    }()

    // Check if the mount process has an error to report.
    select {
    case <-time.After(mountTimeout):
        fuse.Unmount(cleanedMountPoint)
        return nil, errMountTimeout

    case err := <-serverr:
        fuse.Unmount(cleanedMountPoint)
        log.Warn("Error serving swarm FUSE FS", "mountpoint", cleanedMountPoint, "err", err)
        return nil, err

    case <-fconn.Ready:
        log.Info("Now serving swarm FUSE FS", "manifest", mhash, "mountpoint", cleanedMountPoint)
    }

    self.activeMounts[cleanedMountPoint] = mi
    return mi, nil
}

func (self *SwarmFS) Unmount(mountpoint string) (*MountInfo, error) {

    self.swarmFsLock.Lock()
    defer self.swarmFsLock.Unlock()

    cleanedMountPoint, err := filepath.Abs(filepath.Clean(mountpoint))
    if err != nil {
        return nil, err
    }

    mountInfo := self.activeMounts[cleanedMountPoint]

    if mountInfo == nil || mountInfo.MountPoint != cleanedMountPoint {
        return nil, fmt.Errorf("%s is not mounted", cleanedMountPoint)
    }
    err = fuse.Unmount(cleanedMountPoint)
    if err != nil {
        err1 := externalUnMount(cleanedMountPoint)
        if err1 != nil {
            errStr := fmt.Sprintf("UnMount error: %v", err)
            log.Warn(errStr)
            return nil, err1
        }
    }

    mountInfo.fuseConnection.Close()
    delete(self.activeMounts, cleanedMountPoint)

    succString := fmt.Sprintf("UnMounting %v succeeded", cleanedMountPoint)
    log.Info(succString)

    return mountInfo, nil
}

func (self *SwarmFS) Listmounts() []*MountInfo {
    self.swarmFsLock.RLock()
    defer self.swarmFsLock.RUnlock()

    rows := make([]*MountInfo, 0, len(self.activeMounts))
    for _, mi := range self.activeMounts {
        rows = append(rows, mi)
    }
    return rows
}

func (self *SwarmFS) Stop() bool {
    for mp := range self.activeMounts {
        mountInfo := self.activeMounts[mp]
        self.Unmount(mountInfo.MountPoint)
    }
    return true
}