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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package tmpfs is a filesystem implementation backed by memory.
package tmpfs
import (
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/pipe"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
"gvisor.googlesource.com/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.googlesource.com/gvisor/pkg/sentry/usage"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
var fsInfo = fs.Info{
Type: linux.TMPFS_MAGIC,
// TODO: allow configuring a tmpfs size and enforce it.
TotalBlocks: 0,
FreeBlocks: 0,
}
// rename implements fs.InodeOperations.Rename for tmpfs nodes.
func rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
op, ok := oldParent.InodeOperations.(*Dir)
if !ok {
return ramfs.ErrCrossDevice
}
np, ok := newParent.InodeOperations.(*Dir)
if !ok {
return ramfs.ErrCrossDevice
}
return ramfs.Rename(ctx, &op.Dir, oldName, &np.Dir, newName)
}
// Dir is a directory.
//
// +stateify savable
type Dir struct {
ramfs.Dir
// platform is used to allocate storage for tmpfs Files.
platform platform.Platform
}
// NewDir returns a new directory.
func NewDir(ctx context.Context, contents map[string]*fs.Inode, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource, platform platform.Platform) *fs.Inode {
d := &Dir{platform: platform}
d.InitDir(ctx, contents, owner, perms)
// Manually set the CreateOps.
d.CreateOps = d.newCreateOps()
return fs.NewInode(d, msrc, fs.StableAttr{
DeviceID: tmpfsDevice.DeviceID(),
InodeID: tmpfsDevice.NextIno(),
BlockSize: usermem.PageSize,
Type: fs.Directory,
})
}
// afterLoad is invoked by stateify.
func (d *Dir) afterLoad() {
// Per NewDir, manually set the CreateOps.
d.Dir.CreateOps = d.newCreateOps()
}
// newCreateOps builds the custom CreateOps for this Dir.
func (d *Dir) newCreateOps() *ramfs.CreateOps {
return &ramfs.CreateOps{
NewDir: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
return NewDir(ctx, nil, fs.FileOwnerFromContext(ctx), perms, dir.MountSource, d.platform), nil
},
NewFile: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
uattr := fs.WithCurrentTime(ctx, fs.UnstableAttr{
Owner: fs.FileOwnerFromContext(ctx),
Perms: perms,
// Always start unlinked.
Links: 0,
})
iops := NewInMemoryFile(ctx, usage.Tmpfs, uattr, d.platform)
return fs.NewInode(iops, dir.MountSource, fs.StableAttr{
DeviceID: tmpfsDevice.DeviceID(),
InodeID: tmpfsDevice.NextIno(),
BlockSize: usermem.PageSize,
Type: fs.RegularFile,
}), nil
},
NewSymlink: func(ctx context.Context, dir *fs.Inode, target string) (*fs.Inode, error) {
return NewSymlink(ctx, target, fs.FileOwnerFromContext(ctx), dir.MountSource), nil
},
NewBoundEndpoint: func(ctx context.Context, dir *fs.Inode, socket transport.BoundEndpoint, perms fs.FilePermissions) (*fs.Inode, error) {
return NewSocket(ctx, socket, fs.FileOwnerFromContext(ctx), perms, dir.MountSource), nil
},
NewFifo: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
return NewFifo(ctx, fs.FileOwnerFromContext(ctx), perms, dir.MountSource), nil
},
}
}
// Rename implements fs.InodeOperations.Rename.
func (d *Dir) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
return rename(ctx, oldParent, oldName, newParent, newName)
}
// StatFS implments fs.InodeOperations.StatFS.
func (*Dir) StatFS(context.Context) (fs.Info, error) {
return fsInfo, nil
}
// Symlink is a symlink.
//
// +stateify savable
type Symlink struct {
ramfs.Symlink
}
// NewSymlink returns a new symlink with the provided permissions.
func NewSymlink(ctx context.Context, target string, owner fs.FileOwner, msrc *fs.MountSource) *fs.Inode {
s := &Symlink{}
s.InitSymlink(ctx, owner, target)
return fs.NewInode(s, msrc, fs.StableAttr{
DeviceID: tmpfsDevice.DeviceID(),
InodeID: tmpfsDevice.NextIno(),
BlockSize: usermem.PageSize,
Type: fs.Symlink,
})
}
// Rename implements fs.InodeOperations.Rename.
func (s *Symlink) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
return rename(ctx, oldParent, oldName, newParent, newName)
}
// StatFS returns the tmpfs info.
func (s *Symlink) StatFS(context.Context) (fs.Info, error) {
return fsInfo, nil
}
// Socket is a socket.
//
// +stateify savable
type Socket struct {
ramfs.Socket
}
// NewSocket returns a new socket with the provided permissions.
func NewSocket(ctx context.Context, socket transport.BoundEndpoint, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource) *fs.Inode {
s := &Socket{}
s.InitSocket(ctx, socket, owner, perms)
return fs.NewInode(s, msrc, fs.StableAttr{
DeviceID: tmpfsDevice.DeviceID(),
InodeID: tmpfsDevice.NextIno(),
BlockSize: usermem.PageSize,
Type: fs.Socket,
})
}
// Rename implements fs.InodeOperations.Rename.
func (s *Socket) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
return rename(ctx, oldParent, oldName, newParent, newName)
}
// StatFS returns the tmpfs info.
func (s *Socket) StatFS(context.Context) (fs.Info, error) {
return fsInfo, nil
}
// Fifo is a tmpfs named pipe.
//
// +stateify savable
type Fifo struct {
ramfs.Entry
}
// NewFifo creates a new named pipe.
func NewFifo(ctx context.Context, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource) *fs.Inode {
f := &Fifo{}
f.InitEntry(ctx, owner, perms)
iops := pipe.NewInodeOperations(f, pipe.NewPipe(ctx, true /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize))
return fs.NewInode(iops, msrc, fs.StableAttr{
DeviceID: tmpfsDevice.DeviceID(),
InodeID: tmpfsDevice.NextIno(),
BlockSize: usermem.PageSize,
Type: fs.Pipe,
})
}
// Rename implements fs.InodeOperations.Rename.
func (f *Fifo) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
return rename(ctx, oldParent, oldName, newParent, newName)
}
// StatFS returns the tmpfs info.
func (*Fifo) StatFS(context.Context) (fs.Info, error) {
return fsInfo, nil
}
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