github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fsimpl/cgroupfs/job.go (about)

     1  // Copyright 2021 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 cgroupfs
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  
    21  	"github.com/SagerNet/gvisor/pkg/context"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/fsimpl/kernfs"
    23  	"github.com/SagerNet/gvisor/pkg/sentry/kernel/auth"
    24  	"github.com/SagerNet/gvisor/pkg/usermem"
    25  )
    26  
    27  // +stateify savable
    28  type jobController struct {
    29  	controllerCommon
    30  	id int64
    31  }
    32  
    33  var _ controller = (*jobController)(nil)
    34  
    35  func newJobController(fs *filesystem) *jobController {
    36  	c := &jobController{}
    37  	c.controllerCommon.init(controllerJob, fs)
    38  	return c
    39  }
    40  
    41  func (c *jobController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
    42  	contents["job.id"] = c.fs.newControllerWritableFile(ctx, creds, &jobIDData{c: c})
    43  }
    44  
    45  // +stateify savable
    46  type jobIDData struct {
    47  	c *jobController
    48  }
    49  
    50  // Generate implements vfs.DynamicBytesSource.Generate.
    51  func (d *jobIDData) Generate(ctx context.Context, buf *bytes.Buffer) error {
    52  	fmt.Fprintf(buf, "%d\n", d.c.id)
    53  	return nil
    54  }
    55  
    56  // Write implements vfs.WritableDynamicBytesSource.Write.
    57  func (d *jobIDData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
    58  	val, n, err := parseInt64FromString(ctx, src, offset)
    59  	if err != nil {
    60  		return n, err
    61  	}
    62  	d.c.id = val
    63  	return n, nil
    64  }