move ParseCgroupFileUnified from v3/cgroup1 to v3

The function isn't really for cgroup1.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

cgroup1/paths_test.go

@@ -21,6 +21,8 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"github.com/containerd/cgroups/v3"
 )
 
 func TestStaticPath(t *testing.T) {
@@ -89,34 +91,6 @@ func TestRootPath(t *testing.T) {
 	}
 }
 
-func TestEmptySubsystem(t *testing.T) {
-	const data = `10:devices:/user.slice
-	9:net_cls,net_prio:/
-	8:blkio:/
-	7:freezer:/
-	6:perf_event:/
-	5:cpuset:/
-	4:memory:/
-	3:pids:/user.slice/user-1000.slice/user@1000.service
-	2:cpu,cpuacct:/
-	1:name=systemd:/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service
-	0::/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service`
-	r := strings.NewReader(data)
-	paths, unified, err := parseCgroupFromReaderUnified(r)
-	if err != nil {
-		t.Fatal(err)
-	}
-	for subsystem, path := range paths {
-		if subsystem == "" {
-			t.Fatalf("empty subsystem for %q", path)
-		}
-	}
-	unifiedExpected := "/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service"
-	if unified != unifiedExpected {
-		t.Fatalf("expected %q, got %q", unifiedExpected, unified)
-	}
-}
-
 func TestSystemd240(t *testing.T) {
 	if isUnified {
 		t.Skipf("requires the system to be running in legacy mode")
@@ -131,7 +105,7 @@ func TestSystemd240(t *testing.T) {
 	1:name=systemd:/system.slice/docker.service
 	0::/system.slice/docker.service`
 	r := strings.NewReader(data)
-	paths, unified, err := parseCgroupFromReaderUnified(r)
+	paths, unified, err := cgroups.ParseCgroupFromReaderUnified(r)
 	if err != nil {
 		t.Fatal(err)
 	}

cgroup1/utils.go

@@ -19,7 +19,6 @@ package cgroup1
 import (
 	"bufio"
 	"fmt"
-	"io"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -180,49 +179,18 @@ func parseKV(raw string) (string, uint64, error) {
 // etc.
 //
 // The resulting map does not have an element for cgroup v2 unified hierarchy.
-// Use ParseCgroupFileUnified to get the unified path.
+// Use [cgroups.ParseCgroupFileUnified] to get the unified path.
 func ParseCgroupFile(path string) (map[string]string, error) {
 	x, _, err := ParseCgroupFileUnified(path)
 	return x, err
 }
 
 // ParseCgroupFileUnified returns legacy subsystem paths as the first value,
 // and returns the unified path as the second value.
+//
+// Deprecated: use [cgroups.ParseCgroupFileUnified] instead .
 func ParseCgroupFileUnified(path string) (map[string]string, string, error) {
-	f, err := os.Open(path)
-	if err != nil {
-		return nil, "", err
-	}
-	defer f.Close()
-	return parseCgroupFromReaderUnified(f)
-}
-
-func parseCgroupFromReaderUnified(r io.Reader) (map[string]string, string, error) {
-	var (
-		cgroups = make(map[string]string)
-		unified = ""
-		s       = bufio.NewScanner(r)
-	)
-	for s.Scan() {
-		var (
-			text  = s.Text()
-			parts = strings.SplitN(text, ":", 3)
-		)
-		if len(parts) < 3 {
-			return nil, unified, fmt.Errorf("invalid cgroup entry: %q", text)
-		}
-		for _, subs := range strings.Split(parts[1], ",") {
-			if subs == "" {
-				unified = parts[2]
-			} else {
-				cgroups[subs] = parts[2]
-			}
-		}
-	}
-	if err := s.Err(); err != nil {
-		return nil, unified, err
-	}
-	return cgroups, unified, nil
+	return cgroups.ParseCgroupFileUnified(path)
 }
 
 func getCgroupDestination(subsystem string) (string, error) {

utils.go

@@ -19,8 +19,10 @@ package cgroups
 import (
 	"bufio"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 
 	"golang.org/x/sys/unix"
@@ -105,3 +107,44 @@ func RunningInUserNS() bool {
 	})
 	return inUserNS
 }
+
+// ParseCgroupFileUnified returns legacy subsystem paths as the first value,
+// and returns the unified path as the second value.
+func ParseCgroupFileUnified(path string) (map[string]string, string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, "", err
+	}
+	defer f.Close()
+	return ParseCgroupFromReaderUnified(f)
+}
+
+// ParseCgroupFromReaderUnified returns legacy subsystem paths as the first value,
+// and returns the unified path as the second value.
+func ParseCgroupFromReaderUnified(r io.Reader) (map[string]string, string, error) {
+	var (
+		cgroups = make(map[string]string)
+		unified = ""
+		s       = bufio.NewScanner(r)
+	)
+	for s.Scan() {
+		var (
+			text  = s.Text()
+			parts = strings.SplitN(text, ":", 3)
+		)
+		if len(parts) < 3 {
+			return nil, unified, fmt.Errorf("invalid cgroup entry: %q", text)
+		}
+		for _, subs := range strings.Split(parts[1], ",") {
+			if subs == "" {
+				unified = parts[2]
+			} else {
+				cgroups[subs] = parts[2]
+			}
+		}
+	}
+	if err := s.Err(); err != nil {
+		return nil, unified, err
+	}
+	return cgroups, unified, nil
+}

utils_test.go

@@ -0,0 +1,50 @@
+/*
+   Copyright The containerd 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 cgroups
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseCgroupFromReaderUnified(t *testing.T) {
+	const data = `10:devices:/user.slice
+	9:net_cls,net_prio:/
+	8:blkio:/
+	7:freezer:/
+	6:perf_event:/
+	5:cpuset:/
+	4:memory:/
+	3:pids:/user.slice/user-1000.slice/user@1000.service
+	2:cpu,cpuacct:/
+	1:name=systemd:/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service
+	0::/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service`
+	r := strings.NewReader(data)
+	paths, unified, err := ParseCgroupFromReaderUnified(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for subsystem, path := range paths {
+		if subsystem == "" {
+			t.Fatalf("empty subsystem for %q", path)
+		}
+	}
+	unifiedExpected := "/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service"
+	if unified != unifiedExpected {
+		t.Fatalf("expected %q, got %q", unifiedExpected, unified)
+	}
+}