virtcontainers: Initial import

This is a virtcontainers 1.0.8 import into Kata Containers runtime.

virtcontainers is a Go library designed to manage hardware virtualized
pods and containers. It is the core Clear Containers framework and will
become the core Kata Containers framework, as discussed at
https://github.com/kata-containers/runtime/issues/33

Some more more pointers:

virtcontainers README, including some design and architecure notes:
https://github.com/containers/virtcontainers/blob/master/README.md

virtcontainers 1.0 API:
https://github.com/containers/virtcontainers/blob/master/documentation/api/1.0/api.md

Fixes #40

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

virtcontainers/utils.go

@@ -0,0 +1,113 @@
+//
+// Copyright (c) 2017 Intel Corporation
+//
+// 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 virtcontainers
+
+import (
+	"crypto/rand"
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+const cpBinaryName = "cp"
+
+const fileMode0755 = os.FileMode(0755)
+
+func fileCopy(srcPath, dstPath string) error {
+	if srcPath == "" {
+		return fmt.Errorf("Source path cannot be empty")
+	}
+
+	if dstPath == "" {
+		return fmt.Errorf("Destination path cannot be empty")
+	}
+
+	binPath, err := exec.LookPath(cpBinaryName)
+	if err != nil {
+		return err
+	}
+
+	cmd := exec.Command(binPath, srcPath, dstPath)
+
+	return cmd.Run()
+}
+
+func generateRandomBytes(n int) ([]byte, error) {
+	b := make([]byte, n)
+	_, err := rand.Read(b)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return b, nil
+}
+
+func reverseString(s string) string {
+	r := []rune(s)
+
+	length := len(r)
+	for i, j := 0, length-1; i < length/2; i, j = i+1, j-1 {
+		r[i], r[j] = r[j], r[i]
+	}
+
+	return string(r)
+}
+
+func cleanupFds(fds []*os.File, numFds int) {
+
+	maxFds := len(fds)
+
+	if numFds < maxFds {
+		maxFds = numFds
+	}
+
+	for i := 0; i < maxFds; i++ {
+		_ = fds[i].Close()
+	}
+}
+
+// writeToFile opens a file in write only mode and writes bytes to it
+func writeToFile(path string, data []byte) error {
+	f, err := os.OpenFile(path, os.O_WRONLY, fileMode0755)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	if _, err := f.Write(data); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ConstraintsToVCPUs converts CPU quota and period to vCPUs
+func ConstraintsToVCPUs(quota int64, period uint64) uint {
+	if quota != 0 && period != 0 {
+		// Use some math magic to round up to the nearest whole vCPU
+		// (that is, a partial part of a quota request ends up assigning
+		// a whole vCPU, for instance, a request of 1.5 'cpu quotas'
+		// will give 2 vCPUs).
+		// This also has the side effect that we will always allocate
+		// at least 1 vCPU.
+		return uint((uint64(quota) + (period - 1)) / period)
+	}
+
+	return 0
+}