github.com/MerlinKodo/gvisor@v0.0.0-20231110090155-957f62ecf90e/pkg/sentry/uniqueid/context.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 uniqueid defines context.Context keys for obtaining system-wide
    16  // unique identifiers.
    17  package uniqueid
    18  
    19  import (
    20  	"github.com/MerlinKodo/gvisor/pkg/context"
    21  )
    22  
    23  // contextID is the kernel package's type for context.Context.Value keys.
    24  type contextID int
    25  
    26  const (
    27  	// CtxGlobalUniqueID is a Context.Value key for a system-wide
    28  	// unique identifier.
    29  	CtxGlobalUniqueID contextID = iota
    30  
    31  	// CtxGlobalUniqueIDProvider is a Context.Value key for a
    32  	// system-wide unique identifier generator.
    33  	CtxGlobalUniqueIDProvider
    34  
    35  	// CtxInotifyCookie is a Context.Value key for a unique inotify
    36  	// event cookie.
    37  	CtxInotifyCookie
    38  )
    39  
    40  // Provider generates a sequence of unique identifiers useful for,
    41  // among other things, lock ordering.
    42  type Provider interface {
    43  	// UniqueID returns a new unique identifier.
    44  	UniqueID() uint64
    45  }
    46  
    47  // GlobalFromContext returns a system-wide unique identifier from ctx.
    48  func GlobalFromContext(ctx context.Context) uint64 {
    49  	return ctx.Value(CtxGlobalUniqueID).(uint64)
    50  }
    51  
    52  // GlobalProviderFromContext returns a system-wide unique identifier from ctx.
    53  func GlobalProviderFromContext(ctx context.Context) Provider {
    54  	return ctx.Value(CtxGlobalUniqueIDProvider).(Provider)
    55  }
    56  
    57  // InotifyCookie generates a unique inotify event cookie from ctx.
    58  func InotifyCookie(ctx context.Context) uint32 {
    59  	return ctx.Value(CtxInotifyCookie).(uint32)
    60  }