mirror of
https://github.com/netbirdio/gvisor.git
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Fabricio Voznika
67565078bb
LockFD is the generic implementation that can be embedded in FileDescriptionImpl implementations. Unique lock ID is maintained in vfs.FileDescription and is created on demand. Updates #1480 PiperOrigin-RevId: 315604825
78 lines
2.4 KiB
Go
78 lines
2.4 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package memdev
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import (
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"io"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/usermem"
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)
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const nullDevMinor = 3
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// nullDevice implements vfs.Device for /dev/null.
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type nullDevice struct{}
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// Open implements vfs.Device.Open.
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func (nullDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
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fd := &nullFD{}
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if err := fd.vfsfd.Init(fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{
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UseDentryMetadata: true,
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}); err != nil {
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return nil, err
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}
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return &fd.vfsfd, nil
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}
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// nullFD implements vfs.FileDescriptionImpl for /dev/null.
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type nullFD struct {
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vfsfd vfs.FileDescription
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vfs.FileDescriptionDefaultImpl
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vfs.DentryMetadataFileDescriptionImpl
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vfs.NoLockFD
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}
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// Release implements vfs.FileDescriptionImpl.Release.
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func (fd *nullFD) Release() {
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// noop
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}
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// PRead implements vfs.FileDescriptionImpl.PRead.
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func (fd *nullFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
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return 0, io.EOF
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}
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// Read implements vfs.FileDescriptionImpl.Read.
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func (fd *nullFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
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return 0, io.EOF
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}
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// PWrite implements vfs.FileDescriptionImpl.PWrite.
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func (fd *nullFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
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return src.NumBytes(), nil
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}
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// Write implements vfs.FileDescriptionImpl.Write.
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func (fd *nullFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
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return src.NumBytes(), nil
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}
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// Seek implements vfs.FileDescriptionImpl.Seek.
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func (fd *nullFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
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return 0, nil
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}
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