feat: add device wipe and partition devname

Device wipe mostly copied from v1 library with some fixes.

Partition devname was in Talos PR, but it should be better here.

Signed-off-by: Andrey Smirnov <[email protected]>

block/device.go

@@ -31,6 +31,11 @@ func (d *Device) Close() error {
 	return nil
 }
 
+// File returns the underlying file.
+func (d *Device) File() *os.File {
+	return d.f
+}
+
 // DefaultBlockSize is the default block size in bytes.
 const DefaultBlockSize = 512
 
@@ -56,3 +61,18 @@ type DeviceProperties struct {
 	// Rotational is true if the device is a rotational disk.
 	Rotational bool
 }
+
+// Options for NewFromPath.
+type Options struct {
+	Flag int
+}
+
+// Option is a function that modifies Options.
+type Option func(*Options)
+
+// OpenForWrite opens the device for writing.
+func OpenForWrite() Option {
+	return func(o *Options) {
+		o.Flag |= os.O_RDWR
+	}
+}

block/device_linux.go

@@ -19,8 +19,14 @@ import (
 )
 
 // NewFromPath returns a new Device from the specified path.
-func NewFromPath(path string) (*Device, error) {
-	f, err := os.OpenFile(path, os.O_RDONLY|unix.O_CLOEXEC|unix.O_NONBLOCK, 0)
+func NewFromPath(path string, opts ...Option) (*Device, error) {
+	var options Options
+
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	f, err := os.OpenFile(path, options.Flag|unix.O_CLOEXEC|unix.O_NONBLOCK, 0)
 	if err != nil {
 		return nil, err
 	}

block/wipe_linux.go

@@ -0,0 +1,108 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package block
+
+import (
+	"io"
+	"os"
+	"runtime"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// FastWipeRange fast wipe block.
+	FastWipeRange = 1024 * 1024
+)
+
+// Wipe the device contents.
+//
+// In order of availability this tries to perform the following:
+//   - secure discard (secure erase)
+//   - discard with zeros
+//   - zero out via ioctl
+//   - zero out from userland
+func (d *Device) Wipe() (string, error) {
+	size, err := d.GetSize()
+	if err != nil {
+		return "", err
+	}
+
+	return d.WipeRange(0, size)
+}
+
+// FastWipe the device contents.
+//
+// This method is much faster than Wipe(), but it doesn't guarantee
+// that device will be zeroed out completely.
+func (d *Device) FastWipe() error {
+	size, err := d.GetSize()
+	if err != nil {
+		return err
+	}
+
+	// BLKDISCARD is implemented via TRIM on SSDs, it might or might not zero out device contents.
+	r := [2]uint64{0, size}
+
+	// ignoring the error here as DISCARD might be not supported by the device
+	unix.Syscall(unix.SYS_IOCTL, d.f.Fd(), unix.BLKDISCARD, uintptr(unsafe.Pointer(&r[0]))) //nolint: errcheck
+
+	// zero out the first N bytes of the device to clear any partition table
+	wipeLength := min(size, uint64(FastWipeRange))
+
+	_, err = d.WipeRange(0, wipeLength)
+	if err != nil {
+		return err
+	}
+
+	// wipe the last FastWipeRange bytes of the device as well
+	if size >= FastWipeRange*2 {
+		_, err = d.WipeRange(size-FastWipeRange, FastWipeRange)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// WipeRange the device [start, start+length).
+func (d *Device) WipeRange(start, length uint64) (string, error) {
+	r := [2]uint64{start, length}
+
+	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, d.f.Fd(), unix.BLKSECDISCARD, uintptr(unsafe.Pointer(&r[0]))); errno == 0 {
+		runtime.KeepAlive(d)
+
+		return "blksecdiscard", nil
+	}
+
+	var zeroes int
+
+	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, d.f.Fd(), unix.BLKDISCARDZEROES, uintptr(unsafe.Pointer(&zeroes))); errno == 0 && zeroes != 0 {
+		if _, _, errno = unix.Syscall(unix.SYS_IOCTL, d.f.Fd(), unix.BLKDISCARD, uintptr(unsafe.Pointer(&r[0]))); errno == 0 {
+			runtime.KeepAlive(d)
+
+			return "blkdiscardzeros", nil
+		}
+	}
+
+	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, d.f.Fd(), unix.BLKZEROOUT, uintptr(unsafe.Pointer(&r[0]))); errno == 0 {
+		runtime.KeepAlive(d)
+
+		return "blkzeroout", nil
+	}
+
+	zero, err := os.Open("/dev/zero")
+	if err != nil {
+		return "", err
+	}
+
+	defer zero.Close() //nolint: errcheck
+
+	_, err = io.CopyN(d.f, zero, int64(r[1]))
+
+	return "writezeroes", err
+}

block/wipe_linux_test.go

@@ -0,0 +1,101 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package block_test
+
+import (
+	"crypto/rand"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/freddierice/go-losetup/v2"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/siderolabs/go-blockdevice/v2/block"
+)
+
+func TestDeviceWipe(t *testing.T) {
+	if os.Geteuid() != 0 {
+		t.Skip("skipping test; must be root")
+	}
+
+	tmpDir := t.TempDir()
+
+	rawImage := filepath.Join(tmpDir, "image.raw")
+
+	f, err := os.Create(rawImage)
+	require.NoError(t, err)
+
+	require.NoError(t, f.Truncate(int64(2*GiB)))
+
+	t.Cleanup(func() {
+		require.NoError(t, f.Close())
+	})
+
+	var loDev losetup.Device
+
+	loDev, err = losetup.Attach(rawImage, 0, false)
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		assert.NoError(t, loDev.Detach())
+	})
+
+	devPath := loDev.Path()
+
+	devWhole, err := block.NewFromPath(devPath, block.OpenForWrite())
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		assert.NoError(t, devWhole.Close())
+	})
+
+	magic := make([]byte, 1024)
+
+	_, err = io.ReadFull(rand.Reader, magic)
+	require.NoError(t, err)
+
+	_, err = f.WriteAt(magic, 0)
+	require.NoError(t, err)
+
+	_, err = f.WriteAt(magic, 10*MiB)
+	require.NoError(t, err)
+
+	method, err := devWhole.Wipe()
+	require.NoError(t, err)
+
+	t.Logf("wipe method: %s", method)
+
+	assertZeroed(t, f, 0, 1024)
+	assertZeroed(t, f, 10*MiB, 1024)
+
+	_, err = f.WriteAt(magic, 0)
+	require.NoError(t, err)
+
+	_, err = f.WriteAt(magic, 2*GiB-1024)
+	require.NoError(t, err)
+
+	require.NoError(t, devWhole.FastWipe())
+
+	assertZeroed(t, f, 0, 1024)
+	assertZeroed(t, f, 2*GiB-1024, 1024)
+}
+
+func assertZeroed(t *testing.T, f *os.File, offset, length int64) { //nolint:unparam
+	t.Helper()
+
+	buf := make([]byte, length)
+
+	_, err := f.ReadAt(buf, offset)
+	require.NoError(t, err)
+
+	for i, b := range buf {
+		if b != 0 {
+			t.Fatalf("expected zero at offset %d, got %d", offset+int64(i), b)
+		}
+	}
+}

partitioning/gpt/gpt.go

@@ -90,14 +90,14 @@ func (wrapper *deviceWrapper) GetSize() uint64 {
 }
 
 // DeviceFromBlockDevice creates a new Device from a block.Device.
-func DeviceFromBlockDevice(dev *block.Device, f *os.File) (Device, error) {
+func DeviceFromBlockDevice(dev *block.Device) (Device, error) {
 	size, err := dev.GetSize()
 	if err != nil {
 		return nil, err
 	}
 
 	return &deviceWrapper{
-		File:   f,
+		File:   dev.File(),
 		Device: dev,
 		size:   size,
 	}, nil

partitioning/gpt/gpt_test.go

@@ -249,7 +249,7 @@ func TestGPT(t *testing.T) {
 
 			blkdev := block.NewFromFile(disk)
 
-			gptdev, err := gpt.DeviceFromBlockDevice(blkdev, disk)
+			gptdev, err := gpt.DeviceFromBlockDevice(blkdev)
 			require.NoError(t, err)
 
 			table, err := gpt.New(gptdev, test.opts...)

partitioning/partioning_test.go

@@ -0,0 +1,43 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package partitioning_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/siderolabs/go-blockdevice/v2/partitioning"
+)
+
+func TestDevName(t *testing.T) {
+	t.Parallel()
+
+	for _, test := range []struct { //nolint:govet
+		devname   string
+		partition uint
+
+		expected string
+	}{
+		{
+			devname:   "/dev/sda",
+			partition: 1,
+
+			expected: "/dev/sda1",
+		},
+		{
+			devname:   "/dev/nvme0n1",
+			partition: 2,
+
+			expected: "/dev/nvme0n1p2",
+		},
+	} {
+		t.Run(test.devname, func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, test.expected, partitioning.DevName(test.devname, test.partition))
+		})
+	}
+}

partitioning/partitioning.go

@@ -0,0 +1,19 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// Package partitioning implements common partitioning functions.
+package partitioning
+
+import "strconv"
+
+// DevName returns the devname for the partition on a disk.
+func DevName(device string, part uint) string {
+	result := device
+
+	if len(result) > 0 && result[len(result)-1] >= '0' && result[len(result)-1] <= '9' {
+		result += "p"
+	}
+
+	return result + strconv.FormatUint(uint64(part), 10)
+}