github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/kernel/tty.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package kernel
    16  
    17  import "github.com/SagerNet/gvisor/pkg/sync"
    18  
    19  // TTY defines the relationship between a thread group and its controlling
    20  // terminal.
    21  //
    22  // +stateify savable
    23  type TTY struct {
    24  	// Index is the terminal index. It is immutable.
    25  	Index uint32
    26  
    27  	mu sync.Mutex `state:"nosave"`
    28  
    29  	// tg is protected by mu.
    30  	tg *ThreadGroup
    31  }
    32  
    33  // TTY returns the thread group's controlling terminal. If nil, there is no
    34  // controlling terminal.
    35  func (tg *ThreadGroup) TTY() *TTY {
    36  	tg.pidns.owner.mu.RLock()
    37  	defer tg.pidns.owner.mu.RUnlock()
    38  	tg.signalHandlers.mu.Lock()
    39  	defer tg.signalHandlers.mu.Unlock()
    40  	return tg.tty
    41  }