Initial checkin from CRI-O repo

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/system/proc.go

@@ -0,0 +1,113 @@
+package system
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// State is the status of a process.
+type State rune
+
+const ( // Only values for Linux 3.14 and later are listed here
+	Dead        State = 'X'
+	DiskSleep   State = 'D'
+	Running     State = 'R'
+	Sleeping    State = 'S'
+	Stopped     State = 'T'
+	TracingStop State = 't'
+	Zombie      State = 'Z'
+)
+
+// String forms of the state from proc(5)'s documentation for
+// /proc/[pid]/status' "State" field.
+func (s State) String() string {
+	switch s {
+	case Dead:
+		return "dead"
+	case DiskSleep:
+		return "disk sleep"
+	case Running:
+		return "running"
+	case Sleeping:
+		return "sleeping"
+	case Stopped:
+		return "stopped"
+	case TracingStop:
+		return "tracing stop"
+	case Zombie:
+		return "zombie"
+	default:
+		return fmt.Sprintf("unknown (%c)", s)
+	}
+}
+
+// Stat_t represents the information from /proc/[pid]/stat, as
+// described in proc(5) with names based on the /proc/[pid]/status
+// fields.
+type Stat_t struct {
+	// PID is the process ID.
+	PID uint
+
+	// Name is the command run by the process.
+	Name string
+
+	// State is the state of the process.
+	State State
+
+	// StartTime is the number of clock ticks after system boot (since
+	// Linux 2.6).
+	StartTime uint64
+}
+
+// Stat returns a Stat_t instance for the specified process.
+func Stat(pid int) (stat Stat_t, err error) {
+	bytes, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
+	if err != nil {
+		return stat, err
+	}
+	return parseStat(string(bytes))
+}
+
+// GetProcessStartTime is deprecated.  Use Stat(pid) and
+// Stat_t.StartTime instead.
+func GetProcessStartTime(pid int) (string, error) {
+	stat, err := Stat(pid)
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("%d", stat.StartTime), nil
+}
+
+func parseStat(data string) (stat Stat_t, err error) {
+	// From proc(5), field 2 could contain space and is inside `(` and `)`.
+	// The following is an example:
+	// 89653 (gunicorn: maste) S 89630 89653 89653 0 -1 4194560 29689 28896 0 3 146 32 76 19 20 0 1 0 2971844 52965376 3920 18446744073709551615 1 1 0 0 0 0 0 16781312 137447943 0 0 0 17 1 0 0 0 0 0 0 0 0 0 0 0 0 0
+	i := strings.LastIndex(data, ")")
+	if i <= 2 || i >= len(data)-1 {
+		return stat, fmt.Errorf("invalid stat data: %q", data)
+	}
+
+	parts := strings.SplitN(data[:i], "(", 2)
+	if len(parts) != 2 {
+		return stat, fmt.Errorf("invalid stat data: %q", data)
+	}
+
+	stat.Name = parts[1]
+	_, err = fmt.Sscanf(parts[0], "%d", &stat.PID)
+	if err != nil {
+		return stat, err
+	}
+
+	// parts indexes should be offset by 3 from the field number given
+	// proc(5), because parts is zero-indexed and we've removed fields
+	// one (PID) and two (Name) in the paren-split.
+	parts = strings.Split(data[i+2:], " ")
+	var state int
+	fmt.Sscanf(parts[3-3], "%c", &state)
+	stat.State = State(state)
+	fmt.Sscanf(parts[22-3], "%d", &stat.StartTime)
+	return stat, nil
+}