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// Copyright 2018 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 kernel
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sync"
)
// TTY defines the relationship between a thread group and its controlling
// terminal.
//
// +stateify savable
type TTY struct {
// Index is the terminal index. It is immutable.
Index uint32
mu sync.Mutex `state:"nosave"`
// tg is protected by mu.
tg *ThreadGroup
}
// TTY returns the thread group's controlling terminal. If nil, there is no
// controlling terminal.
func (tg *ThreadGroup) TTY() *TTY {
tg.pidns.owner.mu.RLock()
defer tg.pidns.owner.mu.RUnlock()
tg.signalHandlers.mu.Lock()
defer tg.signalHandlers.mu.Unlock()
return tg.tty
}
// SignalForegroundProcessGroup sends the signal to the foreground process
// group of the TTY.
func (tty *TTY) SignalForegroundProcessGroup(info *linux.SignalInfo) {
tty.mu.Lock()
defer tty.mu.Unlock()
tg := tty.tg
if tg == nil {
// This TTY is not a controlling thread group. This can happen
// if it was opened with O_NOCTTY, or if it failed the checks
// on session and leaders in SetControllingTTY(). There is
// nothing to signal.
return
}
tg.pidns.owner.mu.Lock()
tg.signalHandlers.mu.Lock()
fg := tg.processGroup.session.foreground
tg.signalHandlers.mu.Unlock()
tg.pidns.owner.mu.Unlock()
if fg == nil {
// Nothing to signal.
return
}
// SendSignal will take TaskSet.mu and signalHandlers.mu, so we cannot
// hold them here.
if err := fg.SendSignal(info); err != nil {
log.Warningf("failed to signal foreground process group (pgid=%d): %v", fg.id, err)
}
}
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