github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fs/proc/cgroup.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 proc
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/SagerNet/gvisor/pkg/context"
    21  	"github.com/SagerNet/gvisor/pkg/sentry/fs"
    22  )
    23  
    24  // LINT.IfChange
    25  
    26  func newCGroupInode(ctx context.Context, msrc *fs.MountSource, cgroupControllers map[string]string) *fs.Inode {
    27  	// From man 7 cgroups: "For each cgroup hierarchy of which the process
    28  	// is a member, there is one entry containing three colon-separated
    29  	// fields: hierarchy-ID:controller-list:cgroup-path"
    30  
    31  	// The hierarchy ids must be positive integers (for cgroup v1), but the
    32  	// exact number does not matter, so long as they are unique. We can
    33  	// just use a counter, but since linux sorts this file in descending
    34  	// order, we must count down to perserve this behavior.
    35  	i := len(cgroupControllers)
    36  	var data string
    37  	for name, dir := range cgroupControllers {
    38  		data += fmt.Sprintf("%d:%s:%s\n", i, name, dir)
    39  		i--
    40  	}
    41  
    42  	return newStaticProcInode(ctx, msrc, []byte(data))
    43  }
    44  
    45  // LINT.ThenChange(../../fsimpl/proc/tasks_files.go)