gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/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  	"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  	// CtxMemoryCgroupID is the memory cgroup id which the task belongs to.
    29  	CtxMemoryCgroupID
    30  
    31  	// CtxMemoryFileMap is a Context.Value key for mapping
    32  	// MemoryFileOpts.RestoreID to *MemoryFile. This is used for save/restore.
    33  	CtxMemoryFileMap
    34  )
    35  
    36  // MemoryFileFromContext returns the MemoryFile used by ctx, or nil if no such
    37  // MemoryFile exists.
    38  func MemoryFileFromContext(ctx context.Context) *MemoryFile {
    39  	if v := ctx.Value(CtxMemoryFile); v != nil {
    40  		return v.(*MemoryFile)
    41  	}
    42  	return nil
    43  }
    44  
    45  // MemoryCgroupIDFromContext returns the memory cgroup id of the ctx, or
    46  // zero if the ctx does not belong to any memory cgroup.
    47  func MemoryCgroupIDFromContext(ctx context.Context) uint32 {
    48  	if v := ctx.Value(CtxMemoryCgroupID); v != nil {
    49  		return v.(uint32)
    50  	}
    51  	return 0
    52  }
    53  
    54  // MemoryFileMapFromContext returns the memory file map used by ctx, or nil if
    55  // no such map exists.
    56  func MemoryFileMapFromContext(ctx context.Context) map[string]*MemoryFile {
    57  	if v := ctx.Value(CtxMemoryFileMap); v != nil {
    58  		return v.(map[string]*MemoryFile)
    59  	}
    60  	return nil
    61  }