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// Copyright 2020 The gVisor Authors.
//
// 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 vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
)
func copyInPath(t *kernel.Task, addr hostarch.Addr) (fspath.Path, error) {
pathname, err := t.CopyInString(addr, linux.PATH_MAX)
if err != nil {
return fspath.Path{}, err
}
return fspath.Parse(pathname), nil
}
type taskPathOperation struct {
pop vfs.PathOperation
haveStartRef bool
}
func getTaskPathOperation(t *kernel.Task, dirfd int32, path fspath.Path, shouldAllowEmptyPath shouldAllowEmptyPath, shouldFollowFinalSymlink shouldFollowFinalSymlink) (taskPathOperation, error) {
root := t.FSContext().RootDirectoryVFS2()
start := root
haveStartRef := false
if !path.Absolute {
if !path.HasComponents() && !bool(shouldAllowEmptyPath) {
root.DecRef(t)
return taskPathOperation{}, syserror.ENOENT
}
if dirfd == linux.AT_FDCWD {
start = t.FSContext().WorkingDirectoryVFS2()
haveStartRef = true
} else {
dirfile := t.GetFileVFS2(dirfd)
if dirfile == nil {
root.DecRef(t)
return taskPathOperation{}, linuxerr.EBADF
}
start = dirfile.VirtualDentry()
start.IncRef()
haveStartRef = true
dirfile.DecRef(t)
}
}
return taskPathOperation{
pop: vfs.PathOperation{
Root: root,
Start: start,
Path: path,
FollowFinalSymlink: bool(shouldFollowFinalSymlink),
},
haveStartRef: haveStartRef,
}, nil
}
func (tpop *taskPathOperation) Release(t *kernel.Task) {
tpop.pop.Root.DecRef(t)
if tpop.haveStartRef {
tpop.pop.Start.DecRef(t)
tpop.haveStartRef = false
}
}
type shouldAllowEmptyPath bool
const (
disallowEmptyPath shouldAllowEmptyPath = false
allowEmptyPath shouldAllowEmptyPath = true
)
type shouldFollowFinalSymlink bool
const (
nofollowFinalSymlink shouldFollowFinalSymlink = false
followFinalSymlink shouldFollowFinalSymlink = true
)
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