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// Copyright 2022 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package control
import (
"fmt"
"strings"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/kernel"
)
// Cgroups contains the state for cgroupfs related control commands.
type Cgroups struct {
Kernel *kernel.Kernel
}
func (c *Cgroups) findCgroup(ctx context.Context, file CgroupControlFile) (kernel.Cgroup, error) {
ctl, err := file.controller()
if err != nil {
return kernel.Cgroup{}, err
}
return c.Kernel.CgroupRegistry().FindCgroup(ctx, ctl, file.Path)
}
// CgroupControlFile identifies a specific control file within a
// specific cgroup, for the hierarchy with a given controller.
type CgroupControlFile struct {
Controller string `json:"controller"`
Path string `json:"path"`
Name string `json:"name"`
}
func (f *CgroupControlFile) controller() (kernel.CgroupControllerType, error) {
return kernel.ParseCgroupController(f.Controller)
}
// CgroupsResult represents the result of a cgroup operation.
type CgroupsResult struct {
Data string `json:"value"`
IsError bool `json:"is_error"`
}
// AsError interprets the result as an error.
func (r *CgroupsResult) AsError() error {
if r.IsError {
return fmt.Errorf(r.Data)
}
return nil
}
// Unpack splits CgroupsResult into a (value, error) tuple.
func (r *CgroupsResult) Unpack() (string, error) {
if r.IsError {
return "", fmt.Errorf(r.Data)
}
return r.Data, nil
}
func newValue(val string) CgroupsResult {
return CgroupsResult{
Data: strings.TrimSpace(val),
}
}
func newError(err error) CgroupsResult {
return CgroupsResult{
Data: err.Error(),
IsError: true,
}
}
// CgroupsResults represents the list of results for a batch command.
type CgroupsResults struct {
Results []CgroupsResult `json:"results"`
}
func (o *CgroupsResults) appendValue(val string) {
o.Results = append(o.Results, newValue(val))
}
func (o *CgroupsResults) appendError(err error) {
o.Results = append(o.Results, newError(err))
}
// CgroupsReadArg represents the arguments for a single read command.
type CgroupsReadArg struct {
File CgroupControlFile `json:"file"`
}
// CgroupsReadArgs represents the list of arguments for a batched read command.
type CgroupsReadArgs struct {
Args []CgroupsReadArg `json:"args"`
}
// ReadControlFiles is an RPC stub for batch-reading cgroupfs control files.
func (c *Cgroups) ReadControlFiles(args *CgroupsReadArgs, out *CgroupsResults) error {
ctx := c.Kernel.SupervisorContext()
for _, arg := range args.Args {
cg, err := c.findCgroup(ctx, arg.File)
if err != nil {
out.appendError(err)
continue
}
val, err := cg.ReadControl(ctx, arg.File.Name)
if err != nil {
out.appendError(err)
} else {
out.appendValue(val)
}
}
return nil
}
// CgroupsWriteArg represents the arguments for a single write command.
type CgroupsWriteArg struct {
File CgroupControlFile `json:"file"`
Value string `json:"value"`
}
// CgroupsWriteArgs represents the lust of arguments for a batched write command.
type CgroupsWriteArgs struct {
Args []CgroupsWriteArg `json:"args"`
}
// WriteControlFiles is an RPC stub for batch-writing cgroupfs control files.
func (c *Cgroups) WriteControlFiles(args *CgroupsWriteArgs, out *CgroupsResults) error {
ctx := c.Kernel.SupervisorContext()
for _, arg := range args.Args {
cg, err := c.findCgroup(ctx, arg.File)
if err != nil {
out.appendError(err)
continue
}
err = cg.WriteControl(ctx, arg.File.Name, arg.Value)
if err != nil {
out.appendError(err)
} else {
out.appendValue("")
}
}
return nil
}
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