1 files changed, 186 insertions, 0 deletions
diff --git a/vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/paths.go b/vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/paths.go
new file mode 100644
index 000000000..1092331b2
--- /dev/null
+++ b/vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/paths.go
@@ -0,0 +1,186 @@
+package fs
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/utils"
+)
+
+// The absolute path to the root of the cgroup hierarchies.
+var (
+	cgroupRootLock sync.Mutex
+	cgroupRoot     string
+)
+
+const defaultCgroupRoot = "/sys/fs/cgroup"
+
+func initPaths(cg *configs.Cgroup) (map[string]string, error) {
+	root, err := rootPath()
+	if err != nil {
+		return nil, err
+	}
+
+	inner, err := innerPath(cg)
+	if err != nil {
+		return nil, err
+	}
+
+	paths := make(map[string]string)
+	for _, sys := range subsystems {
+		name := sys.Name()
+		path, err := subsysPath(root, inner, name)
+		if err != nil {
+			// The non-presence of the devices subsystem
+			// is considered fatal for security reasons.
+			if cgroups.IsNotFound(err) && (cg.SkipDevices || name != "devices") {
+				continue
+			}
+
+			return nil, err
+		}
+		paths[name] = path
+	}
+
+	return paths, nil
+}
+
+func tryDefaultCgroupRoot() string {
+	var st, pst unix.Stat_t
+
+	// (1) it should be a directory...
+	err := unix.Lstat(defaultCgroupRoot, &st)
+	if err != nil || st.Mode&unix.S_IFDIR == 0 {
+		return ""
+	}
+
+	// (2) ... and a mount point ...
+	err = unix.Lstat(filepath.Dir(defaultCgroupRoot), &pst)
+	if err != nil {
+		return ""
+	}
+
+	if st.Dev == pst.Dev {
+		// parent dir has the same dev -- not a mount point
+		return ""
+	}
+
+	// (3) ... of 'tmpfs' fs type.
+	var fst unix.Statfs_t
+	err = unix.Statfs(defaultCgroupRoot, &fst)
+	if err != nil || fst.Type != unix.TMPFS_MAGIC {
+		return ""
+	}
+
+	// (4) it should have at least 1 entry ...
+	dir, err := os.Open(defaultCgroupRoot)
+	if err != nil {
+		return ""
+	}
+	names, err := dir.Readdirnames(1)
+	if err != nil {
+		return ""
+	}
+	if len(names) < 1 {
+		return ""
+	}
+	// ... which is a cgroup mount point.
+	err = unix.Statfs(filepath.Join(defaultCgroupRoot, names[0]), &fst)
+	if err != nil || fst.Type != unix.CGROUP_SUPER_MAGIC {
+		return ""
+	}
+
+	return defaultCgroupRoot
+}
+
+// rootPath finds and returns path to the root of the cgroup hierarchies.
+func rootPath() (string, error) {
+	cgroupRootLock.Lock()
+	defer cgroupRootLock.Unlock()
+
+	if cgroupRoot != "" {
+		return cgroupRoot, nil
+	}
+
+	// fast path
+	cgroupRoot = tryDefaultCgroupRoot()
+	if cgroupRoot != "" {
+		return cgroupRoot, nil
+	}
+
+	// slow path: parse mountinfo
+	mi, err := cgroups.GetCgroupMounts(false)
+	if err != nil {
+		return "", err
+	}
+	if len(mi) < 1 {
+		return "", errors.New("no cgroup mount found in mountinfo")
+	}
+
+	// Get the first cgroup mount (e.g. "/sys/fs/cgroup/memory"),
+	// use its parent directory.
+	root := filepath.Dir(mi[0].Mountpoint)
+
+	if _, err := os.Stat(root); err != nil {
+		return "", err
+	}
+
+	cgroupRoot = root
+	return cgroupRoot, nil
+}
+
+func innerPath(c *configs.Cgroup) (string, error) {
+	if (c.Name != "" || c.Parent != "") && c.Path != "" {
+		return "", errors.New("cgroup: either Path or Name and Parent should be used")
+	}
+
+	// XXX: Do not remove CleanPath. Path safety is important! -- cyphar
+	innerPath := utils.CleanPath(c.Path)
+	if innerPath == "" {
+		cgParent := utils.CleanPath(c.Parent)
+		cgName := utils.CleanPath(c.Name)
+		innerPath = filepath.Join(cgParent, cgName)
+	}
+
+	return innerPath, nil
+}
+
+func subsysPath(root, inner, subsystem string) (string, error) {
+	// If the cgroup name/path is absolute do not look relative to the cgroup of the init process.
+	if filepath.IsAbs(inner) {
+		mnt, err := cgroups.FindCgroupMountpoint(root, subsystem)
+		// If we didn't mount the subsystem, there is no point we make the path.
+		if err != nil {
+			return "", err
+		}
+
+		// Sometimes subsystems can be mounted together as 'cpu,cpuacct'.
+		return filepath.Join(root, filepath.Base(mnt), inner), nil
+	}
+
+	// Use GetOwnCgroupPath instead of GetInitCgroupPath, because the creating
+	// process could in container and shared pid namespace with host, and
+	// /proc/1/cgroup could point to whole other world of cgroups.
+	parentPath, err := cgroups.GetOwnCgroupPath(subsystem)
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(parentPath, inner), nil
+}
+
+func apply(path string, pid int) error {
+	if path == "" {
+		return nil
+	}
+	if err := os.MkdirAll(path, 0o755); err != nil {
+		return err
+	}
+	return cgroups.WriteCgroupProc(path, pid)
+}