96 lines
2.9 KiB
Go
96 lines
2.9 KiB
Go
// 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 tty
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import (
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/device"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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)
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// ptsDevice is the pseudo-filesystem device.
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var ptsDevice = device.NewAnonDevice()
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// filesystem is a devpts filesystem.
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//
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// This devpts is always in the new "multi-instance" mode. i.e., it contains a
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// ptmx device tied to this mount.
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type filesystem struct{}
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func init() {
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fs.RegisterFilesystem(&filesystem{})
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}
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// Name matches drivers/devpts/indoe.c:devpts_fs_type.name.
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func (*filesystem) Name() string {
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return "devpts"
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}
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// AllowUserMount allows users to mount(2) this file system.
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func (*filesystem) AllowUserMount() bool {
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// TODO: Users may mount this once the terminals are in a
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// usable state.
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return false
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}
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// Flags returns that there is nothing special about this file system.
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func (*filesystem) Flags() fs.FilesystemFlags {
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return 0
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}
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// MountSource returns a devpts root that can be positioned in the vfs.
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func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
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// device is always ignored.
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// No options are supported.
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if data != "" {
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return nil, syserror.EINVAL
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}
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return newDir(ctx, fs.NewMountSource(&superOperations{}, f, flags)), nil
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}
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// superOperations implements fs.MountSourceOperations, preventing caching.
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type superOperations struct{}
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// Revalidate implements fs.DirentOperations.Revalidate.
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//
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// It always returns true, forcing a Lookup for all entries.
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//
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// Slave entries are dropped from dir when their master is closed, so an
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// existing slave Dirent in the tree is not sufficient to guarantee that it
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// still exists on the filesystem.
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func (superOperations) Revalidate(*fs.Dirent) bool {
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return true
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}
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// Keep implements fs.DirentOperations.Keep.
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//
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// Keep returns false because Revalidate would force a lookup on cached entries
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// anyways.
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func (superOperations) Keep(*fs.Dirent) bool {
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return false
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}
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// ResetInodeMappings implements MountSourceOperations.ResetInodeMappings.
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func (superOperations) ResetInodeMappings() {}
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// SaveInodeMapping implements MountSourceOperations.SaveInodeMapping.
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func (superOperations) SaveInodeMapping(*fs.Inode, string) {}
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// Destroy implements MountSourceOperations.Destroy.
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func (superOperations) Destroy() {}
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