Merge pull request #93 from Mashimiao/runtime-test-cgroup-path-validation

runtimetest: add validation of cgroups

Author: Zhou Hao

cgroups/cgroups.go

@@ -0,0 +1,104 @@
+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.Fields(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" {
+			// Check that the mount is properly formated.
+			if numPostFields < 3 {
+				return nil, fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
+			}
+
+			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)
+}