chore: use go-blockdevice for zeroing partitions

Use the `go-blockdevice` library to zero partitions.

Also added a test that writes `ones` to the partition and verifies its
zeroes after zeroing it.

Signed-off-by: Noel Georgi <git@frezbo.dev>

internal/pkg/partition/format.go

@@ -7,9 +7,7 @@ package partition
 
 import (
 	"fmt"
-	"io"
 	"log"
-	"os"
 
 	"github.com/siderolabs/go-blockdevice/blockdevice"
 
@@ -39,7 +37,7 @@ func NewFormatOptions(label string) *FormatOptions {
 // Format zeroes the device and formats it using filesystem type provided.
 func Format(devname string, t *FormatOptions) error {
 	if t.FileSystemType == FilesystemTypeNone {
-		return zeroPartition(devname, int64(t.Size))
+		return zeroPartition(devname)
 	}
 
 	opts := []makefs.Option{makefs.WithForce(t.Force), makefs.WithLabel(t.Label)}
@@ -56,29 +54,17 @@ func Format(devname string, t *FormatOptions) error {
 }
 
 // zeroPartition fills the partition with zeroes.
-func zeroPartition(devname string, size int64) (err error) {
+func zeroPartition(devname string) (err error) {
 	log.Printf("zeroing out %q", devname)
 
-	zeroes, err := os.Open("/dev/zero")
-	if err != nil {
-		return err
-	}
-
-	defer zeroes.Close() //nolint:errcheck
-
-	part, err := os.OpenFile(devname, os.O_WRONLY, 0)
+	part, err := blockdevice.Open(devname, blockdevice.WithExclusiveLock(true))
 	if err != nil {
 		return err
 	}
 
 	defer part.Close() //nolint:errcheck
 
-	// wipe at least minimal header size
-	if size == 0 {
-		size = blockdevice.FastWipeRange
-	}
-
-	_, err = io.CopyN(part, zeroes, size)
+	_, err = part.Wipe()
 
 	return err
 }

internal/pkg/partition/format_test.go

@@ -0,0 +1,157 @@
+// 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 partition provides common utils for system partition format.
+package partition_test
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"testing"
+
+	"github.com/siderolabs/go-blockdevice/blockdevice"
+	"github.com/siderolabs/go-blockdevice/blockdevice/loopback"
+	"github.com/siderolabs/go-blockdevice/blockdevice/partition/gpt"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/siderolabs/talos/internal/pkg/partition"
+)
+
+type manifestSuite struct {
+	suite.Suite
+
+	disk           *os.File
+	loopbackDevice *os.File
+}
+
+const (
+	diskSize = 10 * 1024 * 1024 // 10 MiB
+)
+
+func TestManifestSuite(t *testing.T) {
+	suite.Run(t, new(manifestSuite))
+}
+
+func (suite *manifestSuite) SetupTest() {
+	suite.skipIfNotRoot()
+
+	var err error
+
+	suite.disk, err = os.CreateTemp("", "talos")
+	suite.Require().NoError(err)
+
+	suite.Require().NoError(suite.disk.Truncate(diskSize))
+
+	suite.loopbackDevice, err = loopback.NextLoopDevice()
+	suite.Require().NoError(err)
+
+	suite.T().Logf("Using %s", suite.loopbackDevice.Name())
+
+	suite.Require().NoError(loopback.Loop(suite.loopbackDevice, suite.disk))
+
+	suite.Require().NoError(loopback.LoopSetReadWrite(suite.loopbackDevice))
+}
+
+func (suite *manifestSuite) TearDownTest() {
+	if suite.loopbackDevice != nil {
+		suite.Assert().NoError(loopback.Unloop(suite.loopbackDevice))
+	}
+
+	if suite.disk != nil {
+		suite.Assert().NoError(os.Remove(suite.disk.Name()))
+		suite.Assert().NoError(suite.disk.Close())
+	}
+}
+
+func (suite *manifestSuite) skipIfNotRoot() {
+	if os.Getuid() != 0 {
+		suite.T().Skip("can't run the test as non-root")
+	}
+}
+
+func (suite *manifestSuite) skipUnderBuildkit() {
+	hostname, _ := os.Hostname() //nolint:errcheck
+
+	if hostname == "buildkitsandbox" {
+		suite.T().Skip("test not supported under buildkit as partition devices are not propagated from /dev")
+	}
+}
+
+func (suite *manifestSuite) TestZeroPartition() {
+	suite.skipUnderBuildkit()
+
+	bd, err := blockdevice.Open(suite.loopbackDevice.Name(), blockdevice.WithExclusiveLock(true))
+	suite.Require().NoError(err)
+
+	defer bd.Close() //nolint:errcheck
+
+	pt, err := gpt.New(bd.Device(), gpt.WithMarkMBRBootable(false))
+	suite.Require().NoError(err)
+
+	// Create a partition table with a single partition.
+	_, err = pt.Add(0, gpt.WithMaximumSize(true), gpt.WithPartitionName("zerofill"))
+	suite.Require().NoError(err)
+
+	suite.Require().NoError(pt.Write())
+	suite.Require().NoError(bd.Close())
+
+	bd, err = blockdevice.Open(suite.loopbackDevice.Name(), blockdevice.WithExclusiveLock(true))
+	suite.Require().NoError(err)
+
+	defer bd.Close() //nolint:errcheck
+
+	fills := bytes.NewBuffer(bytes.Repeat([]byte{1}, 10))
+
+	parts, err := bd.GetPartition("zerofill")
+	suite.Require().NoError(err)
+
+	part, err := parts.Path()
+	suite.Require().NoError(err)
+
+	// open the partition as read write
+	dst, err := os.OpenFile(part, os.O_WRONLY, 0o644)
+	suite.Require().NoError(err)
+
+	defer dst.Close() //nolint:errcheck
+
+	// Write some data to the partition.
+	_, err = io.Copy(dst, fills)
+	suite.Require().NoError(err)
+
+	data, err := os.Open(part)
+	suite.Require().NoError(err)
+
+	defer data.Close() //nolint:errcheck
+
+	read := make([]byte, fills.Len())
+
+	_, err = data.Read(read)
+	suite.Require().NoError(err)
+	suite.Require().NoError(data.Close())
+
+	suite.Assert().True(bytes.Equal(fills.Bytes(), read))
+
+	suite.Require().NoError(bd.Close())
+
+	err = partition.Format(part, &partition.FormatOptions{
+		FileSystemType: partition.FilesystemTypeNone,
+	})
+	suite.Require().NoError(err)
+
+	// reading 10 times more than what we wrote should still return 0 since the partition is wiped
+	zerofills := bytes.NewBuffer(bytes.Repeat([]byte{0}, 100))
+
+	data, err = os.Open(part)
+	suite.Require().NoError(err)
+
+	defer data.Close() //nolint:errcheck
+
+	read = make([]byte, zerofills.Len())
+
+	_, err = data.Read(read)
+	suite.Require().NoError(err)
+
+	suite.Assert().True(bytes.Equal(zerofills.Bytes(), read))
+}