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locks.go
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locks.go
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// Copyright 2018-2021 CERN
//
// 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.
//
// In applying this license, CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
package node
import (
"context"
"encoding/json"
"io/fs"
"os"
"path/filepath"
provider "github.com/cs3org/go-cs3apis/cs3/storage/provider/v1beta1"
types "github.com/cs3org/go-cs3apis/cs3/types/v1beta1"
"github.com/cs3org/reva/v2/pkg/appctx"
ctxpkg "github.com/cs3org/reva/v2/pkg/ctx"
"github.com/cs3org/reva/v2/pkg/errtypes"
"github.com/cs3org/reva/v2/pkg/storage/utils/filelocks"
"github.com/cs3org/reva/v2/pkg/utils"
"github.com/pkg/errors"
)
// SetLock sets a lock on the node
func (n *Node) SetLock(ctx context.Context, lock *provider.Lock) error {
lockFilePath := n.LockFilePath()
// check existing lock
if l, _ := n.ReadLock(ctx); l != nil {
lockID, _ := ctxpkg.ContextGetLockID(ctx)
if l.LockId != lockID {
return errtypes.Locked(l.LockId)
}
err := os.Remove(lockFilePath)
if err != nil {
return err
}
}
// ensure parent path exists
if err := os.MkdirAll(filepath.Dir(lockFilePath), 0700); err != nil {
return errors.Wrap(err, "Decomposedfs: error creating parent folder for lock")
}
fileLock, err := filelocks.AcquireWriteLock(n.InternalPath())
if err != nil {
return err
}
defer func() {
rerr := filelocks.ReleaseLock(fileLock)
// if err is non nil we do not overwrite that
if err == nil {
err = rerr
}
}()
// O_EXCL to make open fail when the file already exists
f, err := os.OpenFile(lockFilePath, os.O_EXCL|os.O_CREATE|os.O_WRONLY, 0600)
if err != nil {
return errors.Wrap(err, "Decomposedfs: could not create lock file")
}
defer f.Close()
if err := json.NewEncoder(f).Encode(lock); err != nil {
return errors.Wrap(err, "Decomposedfs: could not write lock file")
}
return err
}
// ReadLock reads the lock id for a node
func (n Node) ReadLock(ctx context.Context) (*provider.Lock, error) {
// ensure parent path exists
if err := os.MkdirAll(filepath.Dir(n.InternalPath()), 0700); err != nil {
return nil, errors.Wrap(err, "Decomposedfs: error creating parent folder for lock")
}
fileLock, err := filelocks.AcquireReadLock(n.InternalPath())
if err != nil {
return nil, err
}
defer func() {
rerr := filelocks.ReleaseLock(fileLock)
// if err is non nil we do not overwrite that
if err == nil {
err = rerr
}
}()
f, err := os.Open(n.LockFilePath())
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
return nil, errtypes.NotFound("no lock found")
}
return nil, errors.Wrap(err, "Decomposedfs: could not open lock file")
}
defer f.Close()
lock := &provider.Lock{}
if err := json.NewDecoder(f).Decode(lock); err != nil {
appctx.GetLogger(ctx).Error().Err(err).Msg("Decomposedfs: could not decode lock file, ignoring")
return nil, errors.Wrap(err, "Decomposedfs: could not read lock file")
}
return lock, err
}
// RefreshLock refreshes the node's lock
func (n *Node) RefreshLock(ctx context.Context, lock *provider.Lock) error {
// ensure parent path exists
if err := os.MkdirAll(filepath.Dir(n.InternalPath()), 0700); err != nil {
return errors.Wrap(err, "Decomposedfs: error creating parent folder for lock")
}
fileLock, err := filelocks.AcquireWriteLock(n.InternalPath())
if err != nil {
return err
}
defer func() {
rerr := filelocks.ReleaseLock(fileLock)
// if err is non nil we do not overwrite that
if err == nil {
err = rerr
}
}()
f, err := os.OpenFile(n.LockFilePath(), os.O_RDWR, os.ModeExclusive)
switch {
case errors.Is(err, fs.ErrNotExist):
return errtypes.PreconditionFailed("lock does not exist")
case err != nil:
return errors.Wrap(err, "Decomposedfs: could not open lock file")
}
defer f.Close()
oldLock := &provider.Lock{}
if err := json.NewDecoder(f).Decode(oldLock); err != nil {
return errors.Wrap(err, "Decomposedfs: could not read lock")
}
// check lock
if oldLock.LockId != lock.LockId {
return errtypes.PreconditionFailed("mismatching lock")
}
u := ctxpkg.ContextMustGetUser(ctx)
if !utils.UserEqual(oldLock.User, u.Id) {
return errtypes.PermissionDenied("cannot refresh lock of another holder")
}
if !utils.UserEqual(oldLock.User, lock.GetUser()) {
return errtypes.PermissionDenied("cannot change holder when refreshing a lock")
}
if err := json.NewEncoder(f).Encode(lock); err != nil {
return errors.Wrap(err, "Decomposedfs: could not write lock file")
}
return err
}
// Unlock unlocks the node
func (n *Node) Unlock(ctx context.Context, lock *provider.Lock) error {
// ensure parent path exists
if err := os.MkdirAll(filepath.Dir(n.InternalPath()), 0700); err != nil {
return errors.Wrap(err, "Decomposedfs: error creating parent folder for lock")
}
fileLock, err := filelocks.AcquireWriteLock(n.InternalPath())
if err != nil {
return err
}
defer func() {
rerr := filelocks.ReleaseLock(fileLock)
// if err is non nil we do not overwrite that
if err == nil {
err = rerr
}
}()
f, err := os.OpenFile(n.LockFilePath(), os.O_RDONLY, os.ModeExclusive)
switch {
case errors.Is(err, fs.ErrNotExist):
return errtypes.PreconditionFailed("lock does not exist")
case err != nil:
return errors.Wrap(err, "Decomposedfs: could not open lock file")
}
defer f.Close()
oldLock := &provider.Lock{}
if err := json.NewDecoder(f).Decode(oldLock); err != nil {
return errors.Wrap(err, "Decomposedfs: could not read lock")
}
// check lock
if lock == nil || (oldLock.LockId != lock.LockId) {
return errtypes.Locked(oldLock.LockId)
}
u := ctxpkg.ContextMustGetUser(ctx)
if !utils.UserEqual(oldLock.User, u.Id) {
return errtypes.PermissionDenied("mismatching holder")
}
if err = os.Remove(f.Name()); err != nil {
return errors.Wrap(err, "Decomposedfs: could not remove lock file")
}
return err
}
// CheckLock compares the context lock with the node lock
func (n *Node) CheckLock(ctx context.Context) error {
lockID, _ := ctxpkg.ContextGetLockID(ctx)
lock, _ := n.ReadLock(ctx)
if lock != nil {
switch lockID {
case "":
return errtypes.Locked(lock.LockId) // no lockid in request
case lock.LockId:
return nil // ok
default:
return errtypes.PreconditionFailed("mismatching lock")
}
}
if lockID != "" {
return errtypes.PreconditionFailed("not locked")
}
return nil // ok
}
func readLocksIntoOpaque(ctx context.Context, n *Node, ri *provider.ResourceInfo) error {
// ensure parent path exists
if err := os.MkdirAll(filepath.Dir(n.InternalPath()), 0700); err != nil {
return errors.Wrap(err, "Decomposedfs: error creating parent folder for lock")
}
fileLock, err := filelocks.AcquireReadLock(n.InternalPath())
if err != nil {
return err
}
defer func() {
rerr := filelocks.ReleaseLock(fileLock)
// if err is non nil we do not overwrite that
if err == nil {
err = rerr
}
}()
f, err := os.Open(n.LockFilePath())
if err != nil {
appctx.GetLogger(ctx).Error().Err(err).Msg("Decomposedfs: could not open lock file")
return err
}
defer f.Close()
lock := &provider.Lock{}
if err := json.NewDecoder(f).Decode(lock); err != nil {
appctx.GetLogger(ctx).Error().Err(err).Msg("Decomposedfs: could not read lock file")
}
// reencode to ensure valid json
var b []byte
if b, err = json.Marshal(lock); err != nil {
appctx.GetLogger(ctx).Error().Err(err).Msg("Decomposedfs: could not marshal locks")
}
if ri.Opaque == nil {
ri.Opaque = &types.Opaque{
Map: map[string]*types.OpaqueEntry{},
}
}
ri.Opaque.Map["lock"] = &types.OpaqueEntry{
Decoder: "json",
Value: b,
}
return err
}
func (n *Node) hasLocks(ctx context.Context) bool {
_, err := os.Stat(n.LockFilePath()) // FIXME better error checking
return err == nil
}