Add containerd shim v2 support. (#13)

* Update vendors

Signed-off-by: Lantao Liu <lantaol@google.com>

* Add containerd shim v2 support.

Signed-off-by: Lantao Liu <lantaol@google.com>

* Add test and doc for containerd-shim-runsc-v1.

Signed-off-by: Lantao Liu <lantaol@google.com>

* Address comments.

1 files changed, 81 insertions, 0 deletions

diff --git a/vendor/github.com/containerd/cgroups/v1.go b/vendor/github.com/containerd/cgroups/v1.go
new file mode 100644
index 000000000..a076d4692
--- /dev/null
+++ b/vendor/github.com/containerd/cgroups/v1.go
@@ -0,0 +1,81 @@
+/*
+   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 (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// V1 returns all the groups in the default cgroups mountpoint in a single hierarchy
+func V1() ([]Subsystem, error) {
+	root, err := v1MountPoint()
+	if err != nil {
+		return nil, err
+	}
+	subsystems, err := defaults(root)
+	if err != nil {
+		return nil, err
+	}
+	var enabled []Subsystem
+	for _, s := range pathers(subsystems) {
+		// check and remove the default groups that do not exist
+		if _, err := os.Lstat(s.Path("/")); err == nil {
+			enabled = append(enabled, s)
+		}
+	}
+	return enabled, nil
+}
+
+// v1MountPoint returns the mount point where the cgroup
+// mountpoints are mounted in a single hiearchy
+func v1MountPoint() (string, error) {
+	f, err := os.Open("/proc/self/mountinfo")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if err := scanner.Err(); err != nil {
+			return "", err
+		}
+		var (
+			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 "", fmt.Errorf("Found no fields post '-' in %q", text)
+		}
+		if postSeparatorFields[0] == "cgroup" {
+			// check that the mount is properly formated.
+			if numPostFields < 3 {
+				return "", fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
+			}
+			return filepath.Dir(fields[4]), nil
+		}
+	}
+	return "", ErrMountPointNotExist
+}