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package utils
import (
"bytes"
"crypto/rand"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"strconv"
"strings"
"sync"
"github.com/containers/common/pkg/cgroups"
"github.com/containers/storage/pkg/archive"
"github.com/godbus/dbus/v5"
"github.com/sirupsen/logrus"
)
// 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, env []string, name string, args ...string) error {
cmd := exec.Command(name, args...)
cmd.Stdin = stdin
cmd.Stdout = stdout
cmd.Stderr = stderr
cmd.Env = env
err := cmd.Run()
if err != nil {
return fmt.Errorf("`%v %v` failed: %v", name, strings.Join(args, " "), err)
}
return nil
}
// UntarToFileSystem untars an os.file of a tarball to a destination in the filesystem
func UntarToFileSystem(dest string, tarball *os.File, options *archive.TarOptions) error {
logrus.Debugf("untarring %s", tarball.Name())
return archive.Untar(tarball, dest, options)
}
// Creates a new tar file and wrties bytes from io.ReadCloser
func CreateTarFromSrc(source string, dest string) error {
file, err := os.Create(dest)
if err != nil {
return fmt.Errorf("could not create tarball file '%s': %w", dest, err)
}
defer file.Close()
return TarToFilesystem(source, file)
}
// TarToFilesystem creates a tarball from source and writes to an os.file
// provided
func TarToFilesystem(source string, tarball *os.File) error {
tb, err := Tar(source)
if err != nil {
return err
}
_, err = io.Copy(tarball, tb)
if err != nil {
return err
}
logrus.Debugf("wrote tarball file %s", tarball.Name())
return nil
}
// Tar creates a tarball from source and returns a readcloser of it
func Tar(source string) (io.ReadCloser, error) {
logrus.Debugf("creating tarball of %s", source)
return archive.Tar(source, archive.Uncompressed)
}
// RemoveScientificNotationFromFloat returns a float without any
// scientific notation if the number has any.
// golang does not handle conversion of float64s that have scientific
// notation in them and otherwise stinks. please replace this if you have
// a better implementation.
func RemoveScientificNotationFromFloat(x float64) (float64, error) {
bigNum := strconv.FormatFloat(x, 'g', -1, 64)
breakPoint := strings.IndexAny(bigNum, "Ee")
if breakPoint > 0 {
bigNum = bigNum[:breakPoint]
}
result, err := strconv.ParseFloat(bigNum, 64)
if err != nil {
return x, fmt.Errorf("unable to remove scientific number from calculations: %w", err)
}
return result, nil
}
var (
runsOnSystemdOnce sync.Once
runsOnSystemd bool
)
// RunsOnSystemd returns whether the system is using systemd
func RunsOnSystemd() bool {
runsOnSystemdOnce.Do(func() {
initCommand, err := ioutil.ReadFile("/proc/1/comm")
// On errors, default to systemd
runsOnSystemd = err != nil || strings.TrimRight(string(initCommand), "\n") == "systemd"
})
return runsOnSystemd
}
func moveProcessPIDFileToScope(pidPath, slice, scope string) error {
data, err := ioutil.ReadFile(pidPath)
if err != nil {
// do not raise an error if the file doesn't exist
if os.IsNotExist(err) {
return nil
}
return fmt.Errorf("cannot read pid file %s: %w", pidPath, err)
}
pid, err := strconv.ParseUint(string(data), 10, 0)
if err != nil {
return fmt.Errorf("cannot parse pid file %s: %w", pidPath, err)
}
return moveProcessToScope(int(pid), slice, scope)
}
func moveProcessToScope(pid int, slice, scope string) error {
err := RunUnderSystemdScope(pid, slice, scope)
// If the PID is not valid anymore, do not return an error.
if dbusErr, ok := err.(dbus.Error); ok {
if dbusErr.Name == "org.freedesktop.DBus.Error.UnixProcessIdUnknown" {
return nil
}
}
return err
}
// MoveRootlessNetnsSlirpProcessToUserSlice moves the slirp4netns process for the rootless netns
// into a different scope so that systemd does not kill it with a container.
func MoveRootlessNetnsSlirpProcessToUserSlice(pid int) error {
randBytes := make([]byte, 4)
_, err := rand.Read(randBytes)
if err != nil {
return err
}
return moveProcessToScope(pid, "user.slice", fmt.Sprintf("rootless-netns-%x.scope", randBytes))
}
// MovePauseProcessToScope moves the pause process used for rootless mode to keep the namespaces alive to
// a separate scope.
func MovePauseProcessToScope(pausePidPath string) {
var err error
for i := 0; i < 10; i++ {
randBytes := make([]byte, 4)
_, err = rand.Read(randBytes)
if err != nil {
logrus.Errorf("failed to read random bytes: %v", err)
continue
}
err = moveProcessPIDFileToScope(pausePidPath, "user.slice", fmt.Sprintf("podman-pause-%x.scope", randBytes))
if err == nil {
return
}
}
if err != nil {
unified, err2 := cgroups.IsCgroup2UnifiedMode()
if err2 != nil {
logrus.Warnf("Failed to detect if running with cgroup unified: %v", err)
}
if RunsOnSystemd() && unified {
logrus.Warnf("Failed to add pause process to systemd sandbox cgroup: %v", err)
} else {
logrus.Debugf("Failed to add pause process to systemd sandbox cgroup: %v", err)
}
}
}
// MaybeMoveToSubCgroup moves the current process in a sub cgroup when
// it is running in the root cgroup on a system that uses cgroupv2.
func MaybeMoveToSubCgroup() error {
unifiedMode, err := cgroups.IsCgroup2UnifiedMode()
if err != nil {
return err
}
if !unifiedMode {
return nil
}
cgroup, err := GetOwnCgroup()
if err != nil {
return err
}
if cgroup == "/" {
return MoveUnderCgroupSubtree("init")
}
return nil
}
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