switch to go vendoring

vendor/github.com/KimMachineGun/automemlimit/memlimit/cgroups.go

@@ -0,0 +1,63 @@
+//go:build linux
+// +build linux
+
+package memlimit
+
+import (
+	"github.com/containerd/cgroups"
+	v2 "github.com/containerd/cgroups/v2"
+)
+
+const (
+	cgroupMountPoint = "/sys/fs/cgroup"
+)
+
+// FromCgroup returns the memory limit based on the cgroups version on this system.
+func FromCgroup() (uint64, error) {
+	switch cgroups.Mode() {
+	case cgroups.Legacy:
+		return FromCgroupV1()
+	case cgroups.Hybrid, cgroups.Unified:
+		return FromCgroupV2()
+	}
+	return 0, ErrNoCgroup
+}
+
+// FromCgroupV1 returns the memory limit from the cgroup v1.
+func FromCgroupV1() (uint64, error) {
+	cg, err := cgroups.Load(cgroups.SingleSubsystem(cgroups.V1, cgroups.Memory), cgroups.RootPath)
+	if err != nil {
+		return 0, err
+	}
+
+	metrics, err := cg.Stat(cgroups.IgnoreNotExist)
+	if err != nil {
+		return 0, err
+	} else if metrics.Memory == nil {
+		return 0, ErrNoLimit
+	}
+
+	return metrics.Memory.HierarchicalMemoryLimit, nil
+}
+
+// FromCgroupV2 returns the memory limit from the cgroup v2.
+func FromCgroupV2() (uint64, error) {
+	path, err := v2.NestedGroupPath("")
+	if err != nil {
+		return 0, err
+	}
+
+	m, err := v2.LoadManager(cgroupMountPoint, path)
+	if err != nil {
+		return 0, err
+	}
+
+	stats, err := m.Stat()
+	if err != nil {
+		return 0, err
+	} else if stats.Memory == nil {
+		return 0, ErrNoLimit
+	}
+
+	return stats.Memory.UsageLimit, nil
+}