Merge pull request #904 from euank/fix-cgroup-parsing-err

cgroups: Fix issue if cgroup path contains :

libcontainer/cgroups/utils.go

@@ -262,6 +262,8 @@ func readProcsFile(dir string) ([]int, error) {
 	return out, nil
 }
 
+// ParseCgroupFile parses the given cgroup file, typically from
+// /proc/<pid>/cgroup, into a map of subgroups to cgroup names.
 func ParseCgroupFile(path string) (map[string]string, error) {
 	f, err := os.Open(path)
 	if err != nil {
@@ -269,7 +271,12 @@ func ParseCgroupFile(path string) (map[string]string, error) {
 	}
 	defer f.Close()
 
-	s := bufio.NewScanner(f)
+	return parseCgroupFromReader(f)
+}
+
+// helper function for ParseCgroupFile to make testing easier
+func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
+	s := bufio.NewScanner(r)
 	cgroups := make(map[string]string)
 
 	for s.Scan() {
@@ -278,7 +285,16 @@ func ParseCgroupFile(path string) (map[string]string, error) {
 		}
 
 		text := s.Text()
-		parts := strings.Split(text, ":")
+		// from cgroups(7):
+		// /proc/[pid]/cgroup
+		// ...
+		// For each cgroup hierarchy ... there is one entry
+		// containing three colon-separated fields of the form:
+		//     hierarchy-ID:subsystem-list:cgroup-path
+		parts := strings.SplitN(text, ":", 3)
+		if len(parts) < 3 {
+			return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
+		}
 
 		for _, subs := range strings.Split(parts[1], ",") {
 			cgroups[subs] = parts[2]

libcontainer/cgroups/utils_test.go

@@ -4,6 +4,8 @@ package cgroups
 
 import (
 	"bytes"
+	"fmt"
+	"reflect"
 	"strings"
 	"testing"
 )
@@ -190,3 +192,56 @@ func BenchmarkGetCgroupMounts(b *testing.B) {
 		}
 	}
 }
+
+func TestParseCgroupString(t *testing.T) {
+	testCases := []struct {
+		input          string
+		expectedError  error
+		expectedOutput map[string]string
+	}{
+		{
+			// Taken from a CoreOS instance running systemd 225 with CPU/Mem
+			// accounting enabled in systemd
+			input: `9:blkio:/
+8:freezer:/
+7:perf_event:/
+6:devices:/system.slice/system-sshd.slice
+5:cpuset:/
+4:cpu,cpuacct:/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service
+3:net_cls,net_prio:/
+2:memory:/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service
+1:name=systemd:/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service`,
+			expectedOutput: map[string]string{
+				"name=systemd": "/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service",
+				"blkio":        "/",
+				"freezer":      "/",
+				"perf_event":   "/",
+				"devices":      "/system.slice/system-sshd.slice",
+				"cpuset":       "/",
+				"cpu":          "/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service",
+				"cpuacct":      "/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service",
+				"net_cls":      "/",
+				"net_prio":     "/",
+				"memory":       "/system.slice/system-sshd.slice/sshd@126-10.240.0.15:22-xxx.yyy.zzz.aaa:33678.service",
+			},
+		},
+		{
+			input:         `malformed input`,
+			expectedError: fmt.Errorf(`invalid cgroup entry: must contain at least two colons: malformed input`),
+		},
+	}
+
+	for ndx, testCase := range testCases {
+		out, err := parseCgroupFromReader(strings.NewReader(testCase.input))
+		if err != nil {
+			if testCase.expectedError == nil || testCase.expectedError.Error() != err.Error() {
+				t.Errorf("%v: expected error %v, got error %v", ndx, testCase.expectedError, err)
+			}
+		} else {
+			if !reflect.DeepEqual(testCase.expectedOutput, out) {
+				t.Errorf("%v: expected output %v, got error %v", ndx, testCase.expectedOutput, out)
+			}
+		}
+	}
+
+}