path: root/swarm/fuse/fuse_file.go

// 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 (
    "errors"
    "io"
    "os"
    "sync"

    "bazil.org/fuse"
    "bazil.org/fuse/fs"
    "github.com/dexon-foundation/dexon/swarm/log"
    "github.com/dexon-foundation/dexon/swarm/storage"
    "golang.org/x/net/context"
)

const (
    MaxAppendFileSize = 10485760 // 10Mb
)

var (
    errInvalidOffset           = errors.New("Invalid offset during write")
    errFileSizeMaxLimixReached = errors.New("File size exceeded max limit")
)

var (
    _ fs.Node         = (*SwarmFile)(nil)
    _ fs.HandleReader = (*SwarmFile)(nil)
    _ fs.HandleWriter = (*SwarmFile)(nil)
)

type SwarmFile struct {
    inode    uint64
    name     string
    path     string
    addr     storage.Address
    fileSize int64
    reader   storage.LazySectionReader

    mountInfo *MountInfo
    lock      *sync.RWMutex
}

func NewSwarmFile(path, fname string, minfo *MountInfo) *SwarmFile {
    newFile := &SwarmFile{
        inode:    NewInode(),
        name:     fname,
        path:     path,
        addr:     nil,
        fileSize: -1, // -1 means , file already exists in swarm and you need to just get the size from swarm
        reader:   nil,

        mountInfo: minfo,
        lock:      &sync.RWMutex{},
    }
    return newFile
}

func (sf *SwarmFile) Attr(ctx context.Context, a *fuse.Attr) error {
    log.Debug("swarmfs Attr", "path", sf.path)
    sf.lock.Lock()
    defer sf.lock.Unlock()
    a.Inode = sf.inode
    //TODO: need to get permission as argument
    a.Mode = 0700
    a.Uid = uint32(os.Getuid())
    a.Gid = uint32(os.Getegid())

    if sf.fileSize == -1 {
        reader, _ := sf.mountInfo.swarmApi.Retrieve(ctx, sf.addr)
        quitC := make(chan bool)
        size, err := reader.Size(ctx, quitC)
        if err != nil {
            log.Error("Couldnt get size of file %s : %v", sf.path, err)
            return err
        }
        sf.fileSize = size
        log.Trace("swarmfs Attr", "size", size)
        close(quitC)
    }
    a.Size = uint64(sf.fileSize)
    return nil
}

func (sf *SwarmFile) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
    log.Debug("swarmfs Read", "path", sf.path, "req.String", req.String())
    sf.lock.RLock()
    defer sf.lock.RUnlock()
    if sf.reader == nil {
        sf.reader, _ = sf.mountInfo.swarmApi.Retrieve(ctx, sf.addr)
    }
    buf := make([]byte, req.Size)
    n, err := sf.reader.ReadAt(buf, req.Offset)
    if err == io.ErrUnexpectedEOF || err == io.EOF {
        err = nil
    }
    resp.Data = buf[:n]
    sf.reader = nil

    return err
}

func (sf *SwarmFile) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse) error {
    log.Debug("swarmfs Write", "path", sf.path, "req.String", req.String())
    if sf.fileSize == 0 && req.Offset == 0 {
        // A new file is created
        err := addFileToSwarm(sf, req.Data, len(req.Data))
        if err != nil {
            return err
        }
        resp.Size = len(req.Data)
    } else if req.Offset <= sf.fileSize {
        totalSize := sf.fileSize + int64(len(req.Data))
        if totalSize > MaxAppendFileSize {
            log.Warn("swarmfs Append file size reached (%v) : (%v)", sf.fileSize, len(req.Data))
            return errFileSizeMaxLimixReached
        }

        err := appendToExistingFileInSwarm(sf, req.Data, req.Offset, int64(len(req.Data)))
        if err != nil {
            return err
        }
        resp.Size = len(req.Data)
    } else {
        log.Warn("swarmfs Invalid write request size(%v) : off(%v)", sf.fileSize, req.Offset)
        return errInvalidOffset
    }
    return nil
}