refactor: rewrite GPT library

This replaces the serde package. The serialization/deserialization process was rigid and
made doing precision work on GPT impossible. This PR allows for serialization/deserialization
of specific fields of the GPT header and partitions.

Signed-off-by: Andrew Rynhard <[email protected]>

blockdevice/blkpg/blkpg_darwin.go

@@ -7,26 +7,24 @@ package blkpg
 import (
 	"fmt"
 	"os"
-
-	"github.com/talos-systems/go-blockdevice/blockdevice/table"
 )
 
 // InformKernelOfAdd invokes the BLKPG_ADD_PARTITION ioctl.
-func InformKernelOfAdd(f *os.File, partition table.Partition) error {
+func InformKernelOfAdd(f *os.File, first, length uint64, n int32) error {
 	return fmt.Errorf("not implemented")
 }
 
 // InformKernelOfResize invokes the BLKPG_RESIZE_PARTITION ioctl.
-func InformKernelOfResize(f *os.File, partition table.Partition) error {
+func InformKernelOfResize(f *os.File, first, length uint64, n int32) error {
 	return fmt.Errorf("not implemented")
 }
 
 // InformKernelOfDelete invokes the BLKPG_DEL_PARTITION ioctl.
-func InformKernelOfDelete(f *os.File, partition table.Partition) error {
+func InformKernelOfDelete(f *os.File, first, length uint64, n int32) error {
 	return fmt.Errorf("not implemented")
 }
 
-// GetKernelPartitions returns kernel state of partitions.
-func GetKernelPartitions(f *os.File, devPath string) ([]KernelPartition, error) {
+// GetKernelPartitions returns kernel partition table state.
+func GetKernelPartitions(f *os.File) ([]KernelPartition, error) {
 	return nil, fmt.Errorf("not implemented")
 }

blockdevice/blkpg/blkpg_linux.go

@@ -19,52 +19,51 @@ import (
 	"golang.org/x/sys/unix"
 
 	"github.com/talos-systems/go-blockdevice/blockdevice/lba"
-	"github.com/talos-systems/go-blockdevice/blockdevice/table"
 	"github.com/talos-systems/go-blockdevice/blockdevice/util"
 )
 
 // InformKernelOfAdd invokes the BLKPG_ADD_PARTITION ioctl.
-func InformKernelOfAdd(f *os.File, partition table.Partition) error {
-	return inform(f, partition, unix.BLKPG_ADD_PARTITION)
+func InformKernelOfAdd(f *os.File, first, length uint64, n int32) error {
+	return inform(f, first, length, n, unix.BLKPG_ADD_PARTITION)
 }
 
 // InformKernelOfResize invokes the BLKPG_RESIZE_PARTITION ioctl.
-func InformKernelOfResize(f *os.File, partition table.Partition) error {
-	return inform(f, partition, unix.BLKPG_RESIZE_PARTITION)
+func InformKernelOfResize(f *os.File, first, length uint64, n int32) error {
+	return inform(f, first, length, n, unix.BLKPG_RESIZE_PARTITION)
 }
 
 // InformKernelOfDelete invokes the BLKPG_DEL_PARTITION ioctl.
-func InformKernelOfDelete(f *os.File, partition table.Partition) error {
-	return inform(f, partition, unix.BLKPG_DEL_PARTITION)
+func InformKernelOfDelete(f *os.File, first, length uint64, n int32) error {
+	return inform(f, first, length, n, unix.BLKPG_DEL_PARTITION)
 }
 
-func inform(f *os.File, partition table.Partition, op int32) (err error) {
+func inform(f *os.File, first, length uint64, n, op int32) (err error) {
 	var (
-		start  int64
-		length int64
+		start int64
+		end   int64
 	)
 
 	switch op {
 	case unix.BLKPG_DEL_PARTITION:
 		start = 0
-		length = 0
+		end = 0
 	default:
-		var l *lba.LogicalBlockAddresser
+		var l *lba.LBA
 
-		if l, err = lba.New(f); err != nil {
+		if l, err = lba.NewLBA(f); err != nil {
 			return err
 		}
 
-		blocksize := int64(l.LogicalBlockSize)
+		blocksize := l.LogicalBlockSize
 
-		start = partition.Start() * blocksize
-		length = partition.Length() * blocksize
+		start = int64(first) * blocksize
+		end = int64(length) * blocksize
 	}
 
 	data := &unix.BlkpgPartition{
 		Start:  start,
-		Length: length,
-		Pno:    partition.No(),
+		Length: end,
+		Pno:    n,
 	}
 
 	arg := &unix.BlkpgIoctlArg{
@@ -82,7 +81,8 @@ func inform(f *os.File, partition table.Partition, op int32) (err error) {
 		)
 
 		if errno != 0 {
-			switch errno { //nolint: exhaustive
+			//nolint: exhaustive
+			switch errno {
 			case unix.EBUSY:
 				return retry.ExpectedError(errno)
 			default:
@@ -105,12 +105,12 @@ func inform(f *os.File, partition table.Partition, op int32) (err error) {
 }
 
 // GetKernelPartitions returns kernel partition table state.
-func GetKernelPartitions(f *os.File, devPath string) ([]KernelPartition, error) {
+func GetKernelPartitions(f *os.File) ([]KernelPartition, error) {
 	result := []KernelPartition{}
 
 	for i := 1; i <= 256; i++ {
-		partName := util.PartName(devPath, i)
-		partPath := filepath.Join("/sys/block", filepath.Base(devPath), partName)
+		partName := util.PartName(f.Name(), i)
+		partPath := filepath.Join("/sys/block", filepath.Base(f.Name()), partName)
 
 		_, err := os.Stat(partPath)
 		if err != nil {

blockdevice/blockdevice_darwin.go

@@ -8,12 +8,12 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/talos-systems/go-blockdevice/blockdevice/table"
+	"github.com/talos-systems/go-blockdevice/blockdevice/partition/gpt"
 )
 
 // BlockDevice represents a block device.
 type BlockDevice struct {
-	table table.PartitionTable
+	table *gpt.GPT
 
 	f *os.File
 }
@@ -30,7 +30,7 @@ func (bd *BlockDevice) Close() error {
 }
 
 // PartitionTable returns the block device partition table.
-func (bd *BlockDevice) PartitionTable() (table.PartitionTable, error) {
+func (bd *BlockDevice) PartitionTable() (*gpt.GPT, error) {
 	return nil, fmt.Errorf("not implemented")
 }
 

blockdevice/blockdevice_linux.go

@@ -16,8 +16,7 @@ import (
 	"github.com/talos-systems/go-retry/retry"
 	"golang.org/x/sys/unix"
 
-	"github.com/talos-systems/go-blockdevice/blockdevice/table"
-	"github.com/talos-systems/go-blockdevice/blockdevice/table/gpt"
+	"github.com/talos-systems/go-blockdevice/blockdevice/partition/gpt"
 )
 
 // Linux headers constants.
@@ -37,7 +36,7 @@ const (
 
 // BlockDevice represents a block device.
 type BlockDevice struct {
-	table table.PartitionTable
+	g *gpt.GPT
 
 	f *os.File
 }
@@ -67,21 +66,16 @@ func Open(devname string, setters ...Option) (bd *BlockDevice, err error) {
 	if opts.CreateGPT {
 		var g *gpt.GPT
 
-		if g, err = gpt.NewGPT(devname, f); err != nil {
-			return nil, err
-		}
-
-		var pt table.PartitionTable
-
-		if pt, err = g.New(); err != nil {
+		g, err = gpt.New(f)
+		if err != nil {
 			return nil, err
 		}
 
-		if err = pt.Write(); err != nil {
+		if err = g.Write(); err != nil {
 			return nil, err
 		}
 
-		bd.table = pt
+		bd.g = g
 	} else {
 		buf := make([]byte, 1)
 		// PMBR protective entry starts at 446. The partition type is at offset
@@ -94,10 +88,10 @@ func Open(devname string, setters ...Option) (bd *BlockDevice, err error) {
 		// For GPT, the partition type should be 0xee (EFI GPT).
 		if bytes.Equal(buf, []byte{0xee}) {
 			var g *gpt.GPT
-			if g, err = gpt.NewGPT(devname, f); err != nil {
+			if g, err = gpt.Open(f); err != nil {
 				return nil, err
 			}
-			bd.table = g
+			bd.g = g
 		}
 	}
 
@@ -110,12 +104,12 @@ func (bd *BlockDevice) Close() error {
 }
 
 // PartitionTable returns the block device partition table.
-func (bd *BlockDevice) PartitionTable() (table.PartitionTable, error) {
-	if bd.table == nil {
+func (bd *BlockDevice) PartitionTable() (*gpt.GPT, error) {
+	if bd.g == nil {
 		return nil, ErrMissingPartitionTable
 	}
 
-	return bd.table, bd.table.Read()
+	return bd.g, bd.g.Read()
 }
 
 // RereadPartitionTable invokes the BLKRRPART ioctl to have the kernel read the
@@ -145,7 +139,8 @@ func (bd *BlockDevice) RereadPartitionTable() error {
 		if _, _, ret = unix.Syscall(unix.SYS_IOCTL, bd.f.Fd(), unix.BLKRRPART, 0); ret == 0 {
 			return nil
 		}
-		switch ret { //nolint: exhaustive
+		//nolint: exhaustive
+		switch ret {
 		case syscall.EBUSY:
 			return retry.ExpectedError(err)
 		default:
@@ -256,17 +251,11 @@ func (bd *BlockDevice) WipeRange(start, length uint64) (string, error) {
 // Reset will reset a block device given a device name.
 // Simply deletes partition table on device.
 func (bd *BlockDevice) Reset() (err error) {
-	var pt table.PartitionTable
-
-	if pt, err = bd.PartitionTable(); err != nil {
-		return err
-	}
-
-	for _, p := range pt.Partitions() {
-		if err = pt.Delete(p); err != nil {
+	for _, p := range bd.g.Partitions().Items() {
+		if err = bd.g.Delete(p); err != nil {
 			return fmt.Errorf("failed to delete partition: %w", err)
 		}
 	}
 
-	return pt.Write()
+	return bd.g.Write()
 }

blockdevice/lba/lba.go

@@ -0,0 +1,59 @@
+// 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 lba
+
+import (
+	"fmt"
+	"os"
+)
+
+// Buffer is an in-memory buffer for writing to byte slices in units of LBA.
+type Buffer struct {
+	lba *LBA
+	b   []byte
+}
+
+// NewBuffer intializes and returns a `Buffer`.
+func NewBuffer(lba *LBA, b []byte) *Buffer {
+	return &Buffer{lba: lba, b: b}
+}
+
+// Read reads from a `Buffer`.
+func (buf *Buffer) Read(off, length int64) (b []byte, err error) {
+	b = make([]byte, length)
+
+	n := copy(b, buf.b[off:off+length])
+
+	if n != len(buf.b[off:off+length]) {
+		return nil, fmt.Errorf("expected to write %d bytes, read %d", len(b), n)
+	}
+
+	return b, nil
+}
+
+// Write writes to a `Buffer`.
+func (buf *Buffer) Write(b []byte, off int64) (err error) {
+	n := copy(buf.b[off:off+int64(len(b))], b)
+
+	if n != len(b) {
+		return fmt.Errorf("expected to write %d bytes, read %d", len(b), n)
+	}
+
+	return nil
+}
+
+// Bytes returns the buffer bytes.
+func (buf *Buffer) Bytes() []byte {
+	return buf.b
+}
+
+// LBA represents logical block addressing.
+type LBA struct {
+	PhysicalBlockSize int64
+	LogicalBlockSize  int64
+	TotalSectors      int64
+
+	f *os.File
+}

blockdevice/lba/lba_darwin.go

@@ -2,42 +2,24 @@
 // 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 lba provides a library for working with Logical Block Addresses.
 package lba
 
 import (
 	"fmt"
 	"os"
 )
 
-// Range represents a range of Logical Block Addresses.
-type Range struct {
-	Start uint64
-	End   uint64
-}
-
-// LogicalBlockAddresser represents Logical Block Addressing.
-type LogicalBlockAddresser struct {
-	PhysicalBlockSize uint64
-	LogicalBlockSize  uint64
-}
-
-// New initializes and returns a LogicalBlockAddresser.
-func New(f *os.File) (lba *LogicalBlockAddresser, err error) {
+// NewLBA initializes and returns an `LBA`.
+func NewLBA(f *os.File) (lba *LBA, err error) {
 	return nil, fmt.Errorf("not implemented")
 }
 
-// Make returns a slice from a source slice in the the specified range inclusively.
-func (lba *LogicalBlockAddresser) Make(size uint64) []byte {
-	return nil
-}
-
-// Copy copies from src to dst in the specified range.
-func (lba *LogicalBlockAddresser) Copy(dst, src []byte, rng Range) (int, error) {
-	return 0, fmt.Errorf("not implemented")
+// ReadAt reads from a file in units of LBA.
+func (l *LBA) ReadAt(lba, off, length int64) (b []byte, err error) {
+	return nil, fmt.Errorf("not implemented")
 }
 
-// From returns a slice from a source slice in the the specified range inclusively.
-func (lba *LogicalBlockAddresser) From(src []byte, rng Range) ([]byte, error) {
-	return nil, fmt.Errorf("not implemented")
+// WriteAt writes to a file in units of LBA.
+func (l *LBA) WriteAt(lba, off int64, b []byte) (err error) {
+	return fmt.Errorf("not implemented")
 }