k3s/vendor/github.com/hanwen/go-fuse/v2/fs/loopback.go
Kohei Tokunaga 8b857eef9c
Ship Stargz Snapshotter (#2936)
* Ship Stargz Snapshotter

Signed-off-by: ktock <ktokunaga.mail@gmail.com>

* Bump github.com/containerd/stargz-snapshotter to v0.8.0

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
2021-09-01 16:27:42 -07:00

418 lines
11 KiB
Go

// Copyright 2019 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fs
import (
"context"
"os"
"path/filepath"
"syscall"
"github.com/hanwen/go-fuse/v2/fuse"
)
// LoopbackRoot holds the parameters for creating a new loopback
// filesystem. Loopback filesystem delegate their operations to an
// underlying POSIX file system.
type LoopbackRoot struct {
// The path to the root of the underlying file system.
Path string
// The device on which the Path resides. This must be set if
// the underlying filesystem crosses file systems.
Dev uint64
// NewNode returns a new InodeEmbedder to be used to respond
// to a LOOKUP/CREATE/MKDIR/MKNOD opcode. If not set, use a
// LoopbackNode.
NewNode func(rootData *LoopbackRoot, parent *Inode, name string, st *syscall.Stat_t) InodeEmbedder
}
func (r *LoopbackRoot) newNode(parent *Inode, name string, st *syscall.Stat_t) InodeEmbedder {
if r.NewNode != nil {
return r.NewNode(r, parent, name, st)
}
return &LoopbackNode{
RootData: r,
}
}
func (r *LoopbackRoot) idFromStat(st *syscall.Stat_t) StableAttr {
// We compose an inode number by the underlying inode, and
// mixing in the device number. In traditional filesystems,
// the inode numbers are small. The device numbers are also
// small (typically 16 bit). Finally, we mask out the root
// device number of the root, so a loopback FS that does not
// encompass multiple mounts will reflect the inode numbers of
// the underlying filesystem
swapped := (uint64(st.Dev) << 32) | (uint64(st.Dev) >> 32)
swappedRootDev := (r.Dev << 32) | (r.Dev >> 32)
return StableAttr{
Mode: uint32(st.Mode),
Gen: 1,
// This should work well for traditional backing FSes,
// not so much for other go-fuse FS-es
Ino: (swapped ^ swappedRootDev) ^ st.Ino,
}
}
// LoopbackNode is a filesystem node in a loopback file system. It is
// public so it can be used as a basis for other loopback based
// filesystems. See NewLoopbackFile or LoopbackRoot for more
// information.
type LoopbackNode struct {
Inode
// RootData points back to the root of the loopback filesystem.
RootData *LoopbackRoot
}
var _ = (NodeStatfser)((*LoopbackNode)(nil))
var _ = (NodeStatfser)((*LoopbackNode)(nil))
var _ = (NodeGetattrer)((*LoopbackNode)(nil))
var _ = (NodeGetxattrer)((*LoopbackNode)(nil))
var _ = (NodeSetxattrer)((*LoopbackNode)(nil))
var _ = (NodeRemovexattrer)((*LoopbackNode)(nil))
var _ = (NodeListxattrer)((*LoopbackNode)(nil))
var _ = (NodeReadlinker)((*LoopbackNode)(nil))
var _ = (NodeOpener)((*LoopbackNode)(nil))
var _ = (NodeCopyFileRanger)((*LoopbackNode)(nil))
var _ = (NodeLookuper)((*LoopbackNode)(nil))
var _ = (NodeOpendirer)((*LoopbackNode)(nil))
var _ = (NodeReaddirer)((*LoopbackNode)(nil))
var _ = (NodeMkdirer)((*LoopbackNode)(nil))
var _ = (NodeMknoder)((*LoopbackNode)(nil))
var _ = (NodeLinker)((*LoopbackNode)(nil))
var _ = (NodeSymlinker)((*LoopbackNode)(nil))
var _ = (NodeUnlinker)((*LoopbackNode)(nil))
var _ = (NodeRmdirer)((*LoopbackNode)(nil))
var _ = (NodeRenamer)((*LoopbackNode)(nil))
func (n *LoopbackNode) Statfs(ctx context.Context, out *fuse.StatfsOut) syscall.Errno {
s := syscall.Statfs_t{}
err := syscall.Statfs(n.path(), &s)
if err != nil {
return ToErrno(err)
}
out.FromStatfsT(&s)
return OK
}
// path returns the full path to the file in the underlying file
// system.
func (n *LoopbackNode) path() string {
path := n.Path(n.Root())
return filepath.Join(n.RootData.Path, path)
}
func (n *LoopbackNode) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*Inode, syscall.Errno) {
p := filepath.Join(n.path(), name)
st := syscall.Stat_t{}
err := syscall.Lstat(p, &st)
if err != nil {
return nil, ToErrno(err)
}
out.Attr.FromStat(&st)
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
return ch, 0
}
// preserveOwner sets uid and gid of `path` according to the caller information
// in `ctx`.
func (n *LoopbackNode) preserveOwner(ctx context.Context, path string) error {
if os.Getuid() != 0 {
return nil
}
caller, ok := fuse.FromContext(ctx)
if !ok {
return nil
}
return syscall.Lchown(path, int(caller.Uid), int(caller.Gid))
}
func (n *LoopbackNode) Mknod(ctx context.Context, name string, mode, rdev uint32, out *fuse.EntryOut) (*Inode, syscall.Errno) {
p := filepath.Join(n.path(), name)
err := syscall.Mknod(p, mode, int(rdev))
if err != nil {
return nil, ToErrno(err)
}
n.preserveOwner(ctx, p)
st := syscall.Stat_t{}
if err := syscall.Lstat(p, &st); err != nil {
syscall.Rmdir(p)
return nil, ToErrno(err)
}
out.Attr.FromStat(&st)
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
return ch, 0
}
func (n *LoopbackNode) Mkdir(ctx context.Context, name string, mode uint32, out *fuse.EntryOut) (*Inode, syscall.Errno) {
p := filepath.Join(n.path(), name)
err := os.Mkdir(p, os.FileMode(mode))
if err != nil {
return nil, ToErrno(err)
}
n.preserveOwner(ctx, p)
st := syscall.Stat_t{}
if err := syscall.Lstat(p, &st); err != nil {
syscall.Rmdir(p)
return nil, ToErrno(err)
}
out.Attr.FromStat(&st)
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
return ch, 0
}
func (n *LoopbackNode) Rmdir(ctx context.Context, name string) syscall.Errno {
p := filepath.Join(n.path(), name)
err := syscall.Rmdir(p)
return ToErrno(err)
}
func (n *LoopbackNode) Unlink(ctx context.Context, name string) syscall.Errno {
p := filepath.Join(n.path(), name)
err := syscall.Unlink(p)
return ToErrno(err)
}
func (n *LoopbackNode) Rename(ctx context.Context, name string, newParent InodeEmbedder, newName string, flags uint32) syscall.Errno {
if flags&RENAME_EXCHANGE != 0 {
return n.renameExchange(name, newParent, newName)
}
p1 := filepath.Join(n.path(), name)
p2 := filepath.Join(n.RootData.Path, newParent.EmbeddedInode().Path(nil), newName)
err := syscall.Rename(p1, p2)
return ToErrno(err)
}
var _ = (NodeCreater)((*LoopbackNode)(nil))
func (n *LoopbackNode) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (inode *Inode, fh FileHandle, fuseFlags uint32, errno syscall.Errno) {
p := filepath.Join(n.path(), name)
flags = flags &^ syscall.O_APPEND
fd, err := syscall.Open(p, int(flags)|os.O_CREATE, mode)
if err != nil {
return nil, nil, 0, ToErrno(err)
}
n.preserveOwner(ctx, p)
st := syscall.Stat_t{}
if err := syscall.Fstat(fd, &st); err != nil {
syscall.Close(fd)
return nil, nil, 0, ToErrno(err)
}
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
lf := NewLoopbackFile(fd)
out.FromStat(&st)
return ch, lf, 0, 0
}
func (n *LoopbackNode) Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (*Inode, syscall.Errno) {
p := filepath.Join(n.path(), name)
err := syscall.Symlink(target, p)
if err != nil {
return nil, ToErrno(err)
}
n.preserveOwner(ctx, p)
st := syscall.Stat_t{}
if err := syscall.Lstat(p, &st); err != nil {
syscall.Unlink(p)
return nil, ToErrno(err)
}
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
out.Attr.FromStat(&st)
return ch, 0
}
func (n *LoopbackNode) Link(ctx context.Context, target InodeEmbedder, name string, out *fuse.EntryOut) (*Inode, syscall.Errno) {
p := filepath.Join(n.path(), name)
err := syscall.Link(filepath.Join(n.RootData.Path, target.EmbeddedInode().Path(nil)), p)
if err != nil {
return nil, ToErrno(err)
}
st := syscall.Stat_t{}
if err := syscall.Lstat(p, &st); err != nil {
syscall.Unlink(p)
return nil, ToErrno(err)
}
node := n.RootData.newNode(n.EmbeddedInode(), name, &st)
ch := n.NewInode(ctx, node, n.RootData.idFromStat(&st))
out.Attr.FromStat(&st)
return ch, 0
}
func (n *LoopbackNode) Readlink(ctx context.Context) ([]byte, syscall.Errno) {
p := n.path()
for l := 256; ; l *= 2 {
buf := make([]byte, l)
sz, err := syscall.Readlink(p, buf)
if err != nil {
return nil, ToErrno(err)
}
if sz < len(buf) {
return buf[:sz], 0
}
}
}
func (n *LoopbackNode) Open(ctx context.Context, flags uint32) (fh FileHandle, fuseFlags uint32, errno syscall.Errno) {
flags = flags &^ syscall.O_APPEND
p := n.path()
f, err := syscall.Open(p, int(flags), 0)
if err != nil {
return nil, 0, ToErrno(err)
}
lf := NewLoopbackFile(f)
return lf, 0, 0
}
func (n *LoopbackNode) Opendir(ctx context.Context) syscall.Errno {
fd, err := syscall.Open(n.path(), syscall.O_DIRECTORY, 0755)
if err != nil {
return ToErrno(err)
}
syscall.Close(fd)
return OK
}
func (n *LoopbackNode) Readdir(ctx context.Context) (DirStream, syscall.Errno) {
return NewLoopbackDirStream(n.path())
}
func (n *LoopbackNode) Getattr(ctx context.Context, f FileHandle, out *fuse.AttrOut) syscall.Errno {
if f != nil {
return f.(FileGetattrer).Getattr(ctx, out)
}
p := n.path()
var err error
st := syscall.Stat_t{}
if &n.Inode == n.Root() {
err = syscall.Stat(p, &st)
} else {
err = syscall.Lstat(p, &st)
}
if err != nil {
return ToErrno(err)
}
out.FromStat(&st)
return OK
}
var _ = (NodeSetattrer)((*LoopbackNode)(nil))
func (n *LoopbackNode) Setattr(ctx context.Context, f FileHandle, in *fuse.SetAttrIn, out *fuse.AttrOut) syscall.Errno {
p := n.path()
fsa, ok := f.(FileSetattrer)
if ok && fsa != nil {
fsa.Setattr(ctx, in, out)
} else {
if m, ok := in.GetMode(); ok {
if err := syscall.Chmod(p, m); err != nil {
return ToErrno(err)
}
}
uid, uok := in.GetUID()
gid, gok := in.GetGID()
if uok || gok {
suid := -1
sgid := -1
if uok {
suid = int(uid)
}
if gok {
sgid = int(gid)
}
if err := syscall.Chown(p, suid, sgid); err != nil {
return ToErrno(err)
}
}
mtime, mok := in.GetMTime()
atime, aok := in.GetATime()
if mok || aok {
ap := &atime
mp := &mtime
if !aok {
ap = nil
}
if !mok {
mp = nil
}
var ts [2]syscall.Timespec
ts[0] = fuse.UtimeToTimespec(ap)
ts[1] = fuse.UtimeToTimespec(mp)
if err := syscall.UtimesNano(p, ts[:]); err != nil {
return ToErrno(err)
}
}
if sz, ok := in.GetSize(); ok {
if err := syscall.Truncate(p, int64(sz)); err != nil {
return ToErrno(err)
}
}
}
fga, ok := f.(FileGetattrer)
if ok && fga != nil {
fga.Getattr(ctx, out)
} else {
st := syscall.Stat_t{}
err := syscall.Lstat(p, &st)
if err != nil {
return ToErrno(err)
}
out.FromStat(&st)
}
return OK
}
// NewLoopbackRoot returns a root node for a loopback file system whose
// root is at the given root. This node implements all NodeXxxxer
// operations available.
func NewLoopbackRoot(rootPath string) (InodeEmbedder, error) {
var st syscall.Stat_t
err := syscall.Stat(rootPath, &st)
if err != nil {
return nil, err
}
root := &LoopbackRoot{
Path: rootPath,
Dev: uint64(st.Dev),
}
return root.newNode(nil, "", &st), nil
}