Initial checkin from CRI-O repo

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

utils/utils.go

@@ -0,0 +1,140 @@
+package utils
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+
+	systemdDbus "github.com/coreos/go-systemd/dbus"
+	"github.com/godbus/dbus"
+)
+
+// ExecCmd executes a command with args and returns its output as a string along
+// with an error, if any
+func ExecCmd(name string, args ...string) (string, error) {
+	cmd := exec.Command(name, args...)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	err := cmd.Run()
+	if err != nil {
+		return "", fmt.Errorf("`%v %v` failed: %v %v (%v)", name, strings.Join(args, " "), stderr.String(), stdout.String(), err)
+	}
+
+	return stdout.String(), nil
+}
+
+// ExecCmdWithStdStreams execute a command with the specified standard streams.
+func ExecCmdWithStdStreams(stdin io.Reader, stdout, stderr io.Writer, name string, args ...string) error {
+	cmd := exec.Command(name, args...)
+	cmd.Stdin = stdin
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("`%v %v` failed: %v", name, strings.Join(args, " "), err)
+	}
+
+	return nil
+}
+
+// StatusToExitCode converts wait status code to an exit code
+func StatusToExitCode(status int) int {
+	return ((status) & 0xff00) >> 8
+}
+
+// RunUnderSystemdScope adds the specified pid to a systemd scope
+func RunUnderSystemdScope(pid int, slice string, unitName string) error {
+	var properties []systemdDbus.Property
+	conn, err := systemdDbus.New()
+	if err != nil {
+		return err
+	}
+	properties = append(properties, systemdDbus.PropSlice(slice))
+	properties = append(properties, newProp("PIDs", []uint32{uint32(pid)}))
+	properties = append(properties, newProp("Delegate", true))
+	properties = append(properties, newProp("DefaultDependencies", false))
+	ch := make(chan string)
+	_, err = conn.StartTransientUnit(unitName, "replace", properties, ch)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	// Block until job is started
+	<-ch
+
+	return nil
+}
+
+func newProp(name string, units interface{}) systemdDbus.Property {
+	return systemdDbus.Property{
+		Name:  name,
+		Value: dbus.MakeVariant(units),
+	}
+}
+
+// DetachError is special error which returned in case of container detach.
+type DetachError struct{}
+
+func (DetachError) Error() string {
+	return "detached from container"
+}
+
+// CopyDetachable is similar to io.Copy but support a detach key sequence to break out.
+func CopyDetachable(dst io.Writer, src io.Reader, keys []byte) (written int64, err error) {
+	if len(keys) == 0 {
+		// Default keys : ctrl-p ctrl-q
+		keys = []byte{16, 17}
+	}
+
+	buf := make([]byte, 32*1024)
+	for {
+		nr, er := src.Read(buf)
+		if nr > 0 {
+			preservBuf := []byte{}
+			for i, key := range keys {
+				preservBuf = append(preservBuf, buf[0:nr]...)
+				if nr != 1 || buf[0] != key {
+					break
+				}
+				if i == len(keys)-1 {
+					// src.Close()
+					return 0, DetachError{}
+				}
+				nr, er = src.Read(buf)
+			}
+			var nw int
+			var ew error
+			if len(preservBuf) > 0 {
+				nw, ew = dst.Write(preservBuf)
+				nr = len(preservBuf)
+			} else {
+				nw, ew = dst.Write(buf[0:nr])
+			}
+			if nw > 0 {
+				written += int64(nw)
+			}
+			if ew != nil {
+				err = ew
+				break
+			}
+			if nr != nw {
+				err = io.ErrShortWrite
+				break
+			}
+		}
+		if er != nil {
+			if er != io.EOF {
+				err = er
+			}
+			break
+		}
+	}
+	return written, err
+}