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Shailend ChandandgVisor bot
b943164ed6
A tty inode was kept alive by a single ownership chain: the stdio file description's reference on the import-time dentry. Everything else that used the inode referred to it uncounted: a file description opened via /dev/tty pins only the devtmpfs dentry, and the controlling-terminal association (ThreadGroup.tty) is a bare pointer. PiperOrigin-RevId: 962479941
62 lines
1.9 KiB
Go
62 lines
1.9 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 ttydev implements a vfs.Device for /dev/tty.
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package ttydev
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/errors/linuxerr"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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)
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const (
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// See drivers/tty/tty_io.c:tty_init().
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ttyDevMinor = 0
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consoleDevMinor = 1
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)
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// ttyDevice implements vfs.Device for /dev/tty.
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//
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// +stateify savable
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type ttyDevice struct{}
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// Open implements vfs.Device.Open.
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func (ttyDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
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t := kernel.TaskFromContext(ctx)
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if t == nil {
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return nil, linuxerr.ENXIO
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}
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tty := t.ThreadGroup().GetTTY()
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if tty == nil {
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return nil, linuxerr.ENXIO
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}
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defer tty.DecRef(ctx) // Ref taken over by OpenTTY.
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// Opening /dev/tty does not set the controlling terminal. See Linux
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// tty_open().
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opts.Flags |= linux.O_NOCTTY
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return tty.OpenTTY(ctx, mnt, vfsd, opts)
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}
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// Register registers all devices implemented by this package in vfsObj.
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func Register(vfsObj *vfs.VirtualFilesystem) error {
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return vfsObj.RegisterDevice(vfs.CharDevice, linux.TTYAUX_MAJOR, ttyDevMinor, ttyDevice{}, &vfs.RegisterDeviceOptions{
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GroupName: "tty",
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Pathname: "tty",
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FilePerms: 0666,
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})
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}
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