Revert "Update runc to 1.0.0"

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs2/freezer.go

@@ -3,20 +3,27 @@
 package fs2
 
 import (
-	"bufio"
 	stdErrors "errors"
-	"fmt"
 	"os"
 	"strings"
-	"time"
 
-	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 )
 
 func setFreezer(dirPath string, state configs.FreezerState) error {
+	if err := supportsFreezer(dirPath); err != nil {
+		// We can ignore this request as long as the user didn't ask us to
+		// freeze the container (since without the freezer cgroup, that's a
+		// no-op).
+		if state == configs.Undefined || state == configs.Thawed {
+			return nil
+		}
+		return errors.Wrap(err, "freezer not supported")
+	}
+
 	var stateStr string
 	switch state {
 	case configs.Undefined:
@@ -29,23 +36,11 @@ func setFreezer(dirPath string, state configs.FreezerState) error {
 		return errors.Errorf("invalid freezer state %q requested", state)
 	}
 
-	fd, err := cgroups.OpenFile(dirPath, "cgroup.freeze", unix.O_RDWR)
-	if err != nil {
-		// We can ignore this request as long as the user didn't ask us to
-		// freeze the container (since without the freezer cgroup, that's a
-		// no-op).
-		if state != configs.Frozen {
-			return nil
-		}
-		return errors.Wrap(err, "freezer not supported")
-	}
-	defer fd.Close()
-
-	if _, err := fd.WriteString(stateStr); err != nil {
+	if err := fscommon.WriteFile(dirPath, "cgroup.freeze", stateStr); err != nil {
 		return err
 	}
 	// Confirm that the cgroup did actually change states.
-	if actualState, err := readFreezer(dirPath, fd); err != nil {
+	if actualState, err := getFreezer(dirPath); err != nil {
 		return err
 	} else if actualState != state {
 		return errors.Errorf(`expected "cgroup.freeze" to be in state %q but was in %q`, state, actualState)
@@ -53,8 +48,13 @@ func setFreezer(dirPath string, state configs.FreezerState) error {
 	return nil
 }
 
+func supportsFreezer(dirPath string) error {
+	_, err := fscommon.ReadFile(dirPath, "cgroup.freeze")
+	return err
+}
+
 func getFreezer(dirPath string) (configs.FreezerState, error) {
-	fd, err := cgroups.OpenFile(dirPath, "cgroup.freeze", unix.O_RDONLY)
+	state, err := fscommon.ReadFile(dirPath, "cgroup.freeze")
 	if err != nil {
 		// If the kernel is too old, then we just treat the freezer as being in
 		// an "undefined" state.
@@ -63,67 +63,12 @@ func getFreezer(dirPath string) (configs.FreezerState, error) {
 		}
 		return configs.Undefined, err
 	}
-	defer fd.Close()
-
-	return readFreezer(dirPath, fd)
-}
-
-func readFreezer(dirPath string, fd *os.File) (configs.FreezerState, error) {
-	if _, err := fd.Seek(0, 0); err != nil {
-		return configs.Undefined, err
-	}
-	state := make([]byte, 2)
-	if _, err := fd.Read(state); err != nil {
-		return configs.Undefined, err
-	}
-	switch string(state) {
-	case "0\n":
+	switch strings.TrimSpace(state) {
+	case "0":
 		return configs.Thawed, nil
-	case "1\n":
-		return waitFrozen(dirPath)
+	case "1":
+		return configs.Frozen, nil
 	default:
 		return configs.Undefined, errors.Errorf(`unknown "cgroup.freeze" state: %q`, state)
 	}
 }
-
-// waitFrozen polls cgroup.events until it sees "frozen 1" in it.
-func waitFrozen(dirPath string) (configs.FreezerState, error) {
-	fd, err := cgroups.OpenFile(dirPath, "cgroup.events", unix.O_RDONLY)
-	if err != nil {
-		return configs.Undefined, err
-	}
-	defer fd.Close()
-
-	// XXX: Simple wait/read/retry is used here. An implementation
-	// based on poll(2) or inotify(7) is possible, but it makes the code
-	// much more complicated. Maybe address this later.
-	const (
-		// Perform maxIter with waitTime in between iterations.
-		waitTime = 10 * time.Millisecond
-		maxIter  = 1000
-	)
-	scanner := bufio.NewScanner(fd)
-	for i := 0; scanner.Scan(); {
-		if i == maxIter {
-			return configs.Undefined, fmt.Errorf("timeout of %s reached waiting for the cgroup to freeze", waitTime*maxIter)
-		}
-		line := scanner.Text()
-		val := strings.TrimPrefix(line, "frozen ")
-		if val != line { // got prefix
-			if val[0] == '1' {
-				return configs.Frozen, nil
-			}
-
-			i++
-			// wait, then re-read
-			time.Sleep(waitTime)
-			_, err := fd.Seek(0, 0)
-			if err != nil {
-				return configs.Undefined, err
-			}
-		}
-	}
-	// Should only reach here either on read error,
-	// or if the file does not contain "frozen " line.
-	return configs.Undefined, scanner.Err()
-}