swarm/api: FUSE read-write support (#13872)

- Moved fuse related code in a new package, swarm/fuse
- Added write support
  - Create new files
  - Delete existing files
  - Append to files (with limitations)
- More test coverage

swarm/fuse/swarmfs.go

@@ -0,0 +1,64 @@
+// 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/>.
+
+package fuse
+
+import (
+	"github.com/ethereum/go-ethereum/swarm/api"
+	"sync"
+	"time"
+)
+
+const (
+	Swarmfs_Version = "0.1"
+	mountTimeout    = time.Second * 5
+	unmountTimeout  = time.Second * 10
+	maxFuseMounts   = 5
+)
+
+var (
+	swarmfs     *SwarmFS // Swarm file system singleton
+	swarmfsLock sync.Once
+
+	inode     uint64 = 1 // global inode
+	inodeLock sync.RWMutex
+)
+
+type SwarmFS struct {
+	swarmApi     *api.Api
+	activeMounts map[string]*MountInfo
+	swarmFsLock  *sync.RWMutex
+}
+
+func NewSwarmFS(api *api.Api) *SwarmFS {
+	swarmfsLock.Do(func() {
+		swarmfs = &SwarmFS{
+			swarmApi:     api,
+			swarmFsLock:  &sync.RWMutex{},
+			activeMounts: map[string]*MountInfo{},
+		}
+	})
+	return swarmfs
+
+}
+
+// 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
+}