2018-04-27 17:37:02 +00:00
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// Copyright 2018 Google Inc.
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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 ashmem implements Android ashmem module (Anonymus Shared Memory).
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package ashmem
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import (
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"sync"
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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)
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// Device implements fs.InodeOperations.
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2018-08-01 22:42:07 +00:00
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//
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// +stateify savable
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2018-04-27 17:37:02 +00:00
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type Device struct {
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2018-08-01 22:42:07 +00:00
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fsutil.DeprecatedFileOperations `state:"nosave"`
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fsutil.InodeNoExtendedAttributes `state:"nosave"`
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fsutil.InodeNotDirectory `state:"nosave"`
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fsutil.InodeNotRenameable `state:"nosave"`
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fsutil.InodeNotSocket `state:"nosave"`
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fsutil.InodeNotSymlink `state:"nosave"`
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fsutil.NoFsync `state:"nosave"`
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fsutil.NoMappable `state:"nosave"`
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fsutil.NoopWriteOut `state:"nosave"`
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fsutil.NotDirReaddir `state:"nosave"`
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2018-04-27 17:37:02 +00:00
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mu sync.Mutex `state:"nosave"`
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unstable fs.UnstableAttr
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}
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// NewDevice creates and intializes a Device structure.
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func NewDevice(ctx context.Context, owner fs.FileOwner, fp fs.FilePermissions) *Device {
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return &Device{
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unstable: fs.WithCurrentTime(ctx, fs.UnstableAttr{
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Owner: owner,
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Perms: fp,
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Links: 1,
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}),
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}
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}
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// Release implements fs.InodeOperations.Release.
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func (ad *Device) Release(context.Context) {}
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// GetFile implements fs.InodeOperations.GetFile.
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func (ad *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
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return fs.NewFile(ctx, d, flags, &Area{
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ad: ad,
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tmpfsFile: nil,
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perms: usermem.AnyAccess,
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}), nil
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}
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// UnstableAttr implements fs.InodeOperations.UnstableAttr.
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func (ad *Device) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
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ad.mu.Lock()
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defer ad.mu.Unlock()
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return ad.unstable, nil
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}
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// Check implements fs.InodeOperations.Check.
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func (ad *Device) Check(ctx context.Context, inode *fs.Inode, p fs.PermMask) bool {
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return fs.ContextCanAccessFile(ctx, inode, p)
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}
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// SetPermissions implements fs.InodeOperations.SetPermissions.
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func (ad *Device) SetPermissions(ctx context.Context, inode *fs.Inode, fp fs.FilePermissions) bool {
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ad.mu.Lock()
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defer ad.mu.Unlock()
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ad.unstable.Perms = fp
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ad.unstable.StatusChangeTime = time.NowFromContext(ctx)
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return true
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}
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// SetOwner implements fs.InodeOperations.SetOwner.
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func (ad *Device) SetOwner(ctx context.Context, inode *fs.Inode, owner fs.FileOwner) error {
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ad.mu.Lock()
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defer ad.mu.Unlock()
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if owner.UID.Ok() {
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ad.unstable.Owner.UID = owner.UID
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}
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if owner.GID.Ok() {
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ad.unstable.Owner.GID = owner.GID
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}
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return nil
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}
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// SetTimestamps implements fs.InodeOperations.SetTimestamps.
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func (ad *Device) SetTimestamps(ctx context.Context, inode *fs.Inode, ts fs.TimeSpec) error {
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if ts.ATimeOmit && ts.MTimeOmit {
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return nil
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}
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ad.mu.Lock()
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defer ad.mu.Unlock()
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now := time.NowFromContext(ctx)
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if !ts.ATimeOmit {
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if ts.ATimeSetSystemTime {
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ad.unstable.AccessTime = now
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} else {
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ad.unstable.AccessTime = ts.ATime
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}
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}
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if !ts.MTimeOmit {
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if ts.MTimeSetSystemTime {
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ad.unstable.ModificationTime = now
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} else {
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ad.unstable.ModificationTime = ts.MTime
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}
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}
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ad.unstable.StatusChangeTime = now
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return nil
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}
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// Truncate implements fs.InodeOperations.WriteOut.
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//
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// Ignored by ashmem.
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func (ad *Device) Truncate(ctx context.Context, inode *fs.Inode, size int64) error {
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return nil
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}
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// AddLink implements fs.InodeOperations.AddLink.
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//
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// Ashmem doesn't support links, no-op.
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func (ad *Device) AddLink() {}
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// DropLink implements fs.InodeOperations.DropLink.
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//
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// Ashmem doesn't support links, no-op.
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func (ad *Device) DropLink() {}
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// NotifyStatusChange implements fs.InodeOperations.NotifyStatusChange.
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func (ad *Device) NotifyStatusChange(ctx context.Context) {
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ad.mu.Lock()
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defer ad.mu.Unlock()
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now := time.NowFromContext(ctx)
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ad.unstable.ModificationTime = now
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ad.unstable.StatusChangeTime = now
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}
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// IsVirtual implements fs.InodeOperations.IsVirtual.
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//
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// Ashmem is virtual.
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func (ad *Device) IsVirtual() bool {
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return true
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}
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// StatFS implements fs.InodeOperations.StatFS.
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//
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// Ashmem doesn't support querying for filesystem info.
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func (ad *Device) StatFS(context.Context) (fs.Info, error) {
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return fs.Info{}, syserror.ENOSYS
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}
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