github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/pkg/sentry/kernel/shm/context.go (about)

     1  // Copyright 2023 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 shm
    16  
    17  import (
    18  	"github.com/metacubex/gvisor/pkg/context"
    19  )
    20  
    21  type contextID int
    22  
    23  const (
    24  	// CtxDeviceID is a Context.Value key for kernel.Kernel.sysVShmDevID, which
    25  	// this package cannot refer to due to dependency cycles.
    26  	CtxDeviceID contextID = iota
    27  )
    28  
    29  func deviceIDFromContext(ctx context.Context) (uint32, bool) {
    30  	v := ctx.Value(CtxDeviceID)
    31  	if v == nil {
    32  		return 0, false
    33  	}
    34  	return v.(uint32), true
    35  }