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package cgroups
import (
"bufio"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
rspec "github.com/opencontainers/runtime-spec/specs-go"
)
var (
// AbsCgroupPath is absolute path for container's cgroup mount
AbsCgroupPath = "/cgrouptest"
// RelCgroupPath is relative path for container's cgroup mount
RelCgroupPath = "testdir/cgrouptest/container"
)
// Cgroup represents interfaces for cgroup validation
type Cgroup interface {
GetBlockIOData(pid int, cgPath string) (*rspec.LinuxBlockIO, error)
GetCPUData(pid int, cgPath string) (*rspec.LinuxCPU, error)
GetDevicesData(pid int, cgPath string) ([]rspec.LinuxDeviceCgroup, error)
GetHugepageLimitData(pid int, cgPath string) ([]rspec.LinuxHugepageLimit, error)
GetMemoryData(pid int, cgPath string) (*rspec.LinuxMemory, error)
GetNetworkData(pid int, cgPath string) (*rspec.LinuxNetwork, error)
GetPidsData(pid int, cgPath string) (*rspec.LinuxPids, error)
}
// FindCgroup gets cgroup root mountpoint
func FindCgroup() (Cgroup, error) {
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return nil, err
}
defer f.Close()
cgroupv2 := false
scanner := bufio.NewScanner(f)
for scanner.Scan() {
text := scanner.Text()
fields := strings.Split(text, " ")
// Safe as mountinfo encodes mountpoints with spaces as \040.
index := strings.Index(text, " - ")
postSeparatorFields := strings.Split(text[index+3:], " ")
numPostFields := len(postSeparatorFields)
// This is an error as we can't detect if the mount is for "cgroup"
if numPostFields == 0 {
return nil, fmt.Errorf("Found no fields post '-' in %q", text)
}
if postSeparatorFields[0] == "cgroup" {
// No need to parse the rest of the postSeparatorFields
cg := &CgroupV1{
MountPath: filepath.Dir(fields[4]),
}
return cg, nil
} else if postSeparatorFields[0] == "cgroup2" {
cgroupv2 = true
continue
//TODO cgroupv2 unimplemented
}
}
if err := scanner.Err(); err != nil {
return nil, err
}
if cgroupv2 {
return nil, fmt.Errorf("cgroupv2 is not supported yet")
}
return nil, fmt.Errorf("cgroup is not found")
}
// GetSubsystemPath gets path of subsystem
func GetSubsystemPath(pid int, subsystem string) (string, error) {
contents, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/cgroup", pid))
if err != nil {
return "", err
}
parts := strings.Split(strings.TrimSpace(string(contents)), "\n")
for _, part := range parts {
elem := strings.SplitN(part, ":", 3)
if len(elem) < 3 {
continue
}
subelems := strings.Split(elem[1], ",")
for _, subelem := range subelems {
if subelem == subsystem {
return elem[2], nil
}
}
}
return "", fmt.Errorf("subsystem %s not found", subsystem)
}
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