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

     1  // Copyright 2019 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 pgalloc
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/context"
    19  )
    20  
    21  // contextID is this package's type for context.Context.Value keys.
    22  type contextID int
    23  
    24  const (
    25  	// CtxMemoryFile is a Context.Value key for a MemoryFile.
    26  	CtxMemoryFile contextID = iota
    27  
    28  	// CtxMemoryFileProvider is a Context.Value key for a MemoryFileProvider.
    29  	CtxMemoryFileProvider
    30  )
    31  
    32  // MemoryFileFromContext returns the MemoryFile used by ctx, or nil if no such
    33  // MemoryFile exists.
    34  func MemoryFileFromContext(ctx context.Context) *MemoryFile {
    35  	if v := ctx.Value(CtxMemoryFile); v != nil {
    36  		return v.(*MemoryFile)
    37  	}
    38  	return nil
    39  }
    40  
    41  // MemoryFileProviderFromContext returns the MemoryFileProvider used by ctx, or nil if no such
    42  // MemoryFileProvider exists.
    43  func MemoryFileProviderFromContext(ctx context.Context) MemoryFileProvider {
    44  	if v := ctx.Value(CtxMemoryFileProvider); v != nil {
    45  		return v.(MemoryFileProvider)
    46  	}
    47  	return nil
    48  }