summaryrefslogtreecommitdiff
path: root/utils/utils.go
blob: 997de150dc13f9f74d6b4498d0dacfa1cca87f5e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
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)
		}
	}
}