prodos: test struct marshal/unmarshal roundtrips

This commit is contained in:
Zellyn Hunter 2017-03-14 21:27:02 -04:00
parent 4b4612c31f
commit 570bf171ac
2 changed files with 217 additions and 85 deletions

View File

@ -2,9 +2,6 @@
// Package prodos contains routines for working with the on-disk
// structures of Apple ProDOS.
//
// TODO(zellyn): remove errors from FromBlock(), and move validation
// into separate Validate() functions.
package prodos
import (
@ -108,21 +105,25 @@ func (dt DateTime) toBytes() []byte {
}
// fromBytes turns a slice of four bytes back into a DateTime.
func (dt *DateTime) fromBytes(b []byte) error {
func (dt *DateTime) fromBytes(b []byte) {
if len(b) != 4 {
return fmt.Errorf("DateTime expects 4 bytes; got %d", len(b))
}
if b[2] >= 0x20 {
return fmt.Errorf("DateTime expects hour<0x20; got 0x%02x", b[2])
}
if b[3] >= 0x40 {
return fmt.Errorf("DateTime expects minute<0x40; got 0x%02x", b[3])
panic(fmt.Sprintf("DateTime expects 4 bytes; got %d", len(b)))
}
dt.YMD[0] = b[0]
dt.YMD[1] = b[1]
dt.HM[0] = b[2]
dt.HM[1] = b[3]
return nil
}
// Validate checks a DateTime for problems, returning a slice of errors
func (dt DateTime) Validate(fieldDescription string) (errors []error) {
if dt.HM[0] >= 24 {
errors = append(errors, fmt.Errorf("%s expects hour<24; got %d", fieldDescription, dt.HM[0]))
}
if dt.HM[1] >= 60 {
errors = append(errors, fmt.Errorf("%s expects minute<60; got %x", fieldDescription, dt.HM[1]))
}
return errors
}
// VolumeDirectoryKeyBlock is the struct used to hold the ProDOS Volume Directory Key
@ -132,6 +133,7 @@ type VolumeDirectoryKeyBlock struct {
Next uint16 // Pointer to next block in the Volume Directory
Header VolumeDirectoryHeader
Descriptors [12]FileDescriptor
Extra byte // Trailing byte (so we don't lose it)
}
// ToBlock marshals the VolumeDirectoryKeyBlock to a Block of bytes.
@ -143,25 +145,34 @@ func (vdkb VolumeDirectoryKeyBlock) ToBlock() Block {
for i, desc := range vdkb.Descriptors {
copyBytes(block[0x2b+i*0x27:0x2b+(i+1)*0x27], desc.toBytes())
}
block[511] = vdkb.Extra
return block
}
// FromBlock unmarshals a Block of bytes into a VolumeDirectoryKeyBlock.
func (vdkb *VolumeDirectoryKeyBlock) FromBlock(block Block) error {
func (vdkb *VolumeDirectoryKeyBlock) FromBlock(block Block) {
vdkb.Prev = binary.LittleEndian.Uint16(block[0x0:0x2])
if vdkb.Prev != 0 {
return fmt.Errorf("Volume Directory Key Block should have a `Previous` block of 0, got $%04x", vdkb.Prev)
}
vdkb.Next = binary.LittleEndian.Uint16(block[0x2:0x4])
if err := vdkb.Header.fromBytes(block[0x04:0x2b]); err != nil {
return err
}
vdkb.Header.fromBytes(block[0x04:0x2b])
for i := range vdkb.Descriptors {
if err := vdkb.Descriptors[i].fromBytes(block[0x2b+i*0x27 : 0x2b+(i+1)*0x27]); err != nil {
return fmt.Errorf("cannot deserialize file descriptor %d of Volume Directory Key Block: %v", err)
}
vdkb.Descriptors[i].fromBytes(block[0x2b+i*0x27 : 0x2b+(i+1)*0x27])
}
return nil
vdkb.Extra = block[511]
}
// Validate validates a VolumeDirectoryKeyBlock for valid values.
func (vdkb VolumeDirectoryKeyBlock) Validate() (errors []error) {
if vdkb.Prev != 0 {
errors = append(errors, fmt.Errorf("Volume Directory Key Block should have a `Previous` block of 0, got $%04x", vdkb.Prev))
}
errors = append(errors, vdkb.Header.Validate()...)
for _, desc := range vdkb.Descriptors {
errors = append(errors, desc.Validate()...)
}
if vdkb.Extra != 0 {
errors = append(errors, fmt.Errorf("Expected last byte of Volume Directory Key Block == 0x0; got 0x%02x", vdkb.Extra))
}
return errors
}
// VolumeDirectoryBlock is a normal (non-key) segment in the Volume Directory Header.
@ -169,6 +180,7 @@ type VolumeDirectoryBlock struct {
Prev uint16 // Pointer to previous block in the Volume Directory.
Next uint16 // Pointer to next block in the Volume Directory.
Descriptors [13]FileDescriptor
Extra byte // Trailing byte (so we don't lose it)
}
// ToBlock marshals a VolumeDirectoryBlock to a Block of bytes.
@ -179,19 +191,29 @@ func (vdb VolumeDirectoryBlock) ToBlock() Block {
for i, desc := range vdb.Descriptors {
copyBytes(block[0x04+i*0x27:0x04+(i+1)*0x27], desc.toBytes())
}
block[511] = vdb.Extra
return block
}
// FromBlock unmarshals a Block of bytes into a VolumeDirectoryBlock.
func (vdb *VolumeDirectoryBlock) FromBlock(block Block) error {
func (vdb *VolumeDirectoryBlock) FromBlock(block Block) {
vdb.Prev = binary.LittleEndian.Uint16(block[0x0:0x2])
vdb.Next = binary.LittleEndian.Uint16(block[0x2:0x4])
for i := range vdb.Descriptors {
if err := vdb.Descriptors[i].fromBytes(block[0x4+i*0x27 : 0x4+(i+1)*0x27]); err != nil {
return fmt.Errorf("cannot deserialize file descriptor %d of Volume Directory Block: %v", err)
}
vdb.Descriptors[i].fromBytes(block[0x4+i*0x27 : 0x4+(i+1)*0x27])
}
return nil
vdb.Extra = block[511]
}
// Validate validates a VolumeDirectoryBlock for valid values.
func (vdb VolumeDirectoryBlock) Validate() (errors []error) {
for _, desc := range vdb.Descriptors {
errors = append(errors, desc.Validate()...)
}
if vdb.Extra != 0 {
errors = append(errors, fmt.Errorf("Expected last byte of Volume Directory Block == 0x0; got 0x%02x", vdb.Extra))
}
return errors
}
type VolumeDirectoryHeader struct {
@ -221,32 +243,35 @@ func (vdh VolumeDirectoryHeader) toBytes() []byte {
buf[0x1e] = byte(vdh.Access)
buf[0x1f] = vdh.EntryLength
buf[0x20] = vdh.EntriesPerBlock
binary.LittleEndian.PutUint16(buf[0x20:0x22], vdh.FileCount)
binary.LittleEndian.PutUint16(buf[0x22:0x24], vdh.BitMapPointer)
binary.LittleEndian.PutUint16(buf[0x24:0x26], vdh.TotalBlocks)
binary.LittleEndian.PutUint16(buf[0x21:0x23], vdh.FileCount)
binary.LittleEndian.PutUint16(buf[0x23:0x25], vdh.BitMapPointer)
binary.LittleEndian.PutUint16(buf[0x25:0x27], vdh.TotalBlocks)
return buf
}
// fromBytes unmarshals a slice of bytes into a VolumeDirectoryHeader.
func (vdh *VolumeDirectoryHeader) fromBytes(buf []byte) error {
func (vdh *VolumeDirectoryHeader) fromBytes(buf []byte) {
if len(buf) != 0x27 {
return fmt.Errorf("VolumeDirectoryHeader should be 0x27 bytes long; got 0x%02x", len(buf))
panic(fmt.Sprintf("VolumeDirectoryHeader should be 0x27 bytes long; got 0x%02x", len(buf)))
}
vdh.TypeAndNameLength = buf[0]
copyBytes(vdh.VolumeName[:], buf[1:0x10])
copyBytes(vdh.Unused1[:], buf[0x10:0x18])
if err := vdh.Creation.fromBytes(buf[0x18:0x1c]); err != nil {
return fmt.Errorf("unable to deserialize Volume Directory Header Creation date/time: %v", err)
}
vdh.Creation.fromBytes(buf[0x18:0x1c])
vdh.Version = buf[0x1c]
vdh.MinVersion = buf[0x1d]
vdh.Access = Access(buf[0x1e])
vdh.EntryLength = buf[0x1f]
vdh.EntriesPerBlock = buf[0x20]
vdh.FileCount = binary.LittleEndian.Uint16(buf[0x20:0x22])
vdh.BitMapPointer = binary.LittleEndian.Uint16(buf[0x22:0x24])
vdh.TotalBlocks = binary.LittleEndian.Uint16(buf[0x24:0x26])
return nil
vdh.FileCount = binary.LittleEndian.Uint16(buf[0x21:0x23])
vdh.BitMapPointer = binary.LittleEndian.Uint16(buf[0x23:0x25])
vdh.TotalBlocks = binary.LittleEndian.Uint16(buf[0x25:0x27])
}
// Validate validates a VolumeDirectoryHeader for valid values.
func (vdh VolumeDirectoryHeader) Validate() (errors []error) {
errors = append(errors, vdh.Creation.Validate("creation date/time of VolumeDirectoryHeader")...)
return errors
}
type Access byte
@ -282,8 +307,8 @@ type FileDescriptor struct {
HeaderPointer uint16 // Block number of the key block for the directory which describes this file.
}
// Filename returns the string filename of a file descriptor.
func (fd FileDescriptor) Filename() string {
// Name returns the string filename of a file descriptor.
func (fd FileDescriptor) Name() string {
return string(fd.FileName[0 : fd.TypeAndNameLength&0xf])
}
@ -307,30 +332,30 @@ func (fd FileDescriptor) toBytes() []byte {
}
// fromBytes unmarshals a slice of bytes into a FileDescriptor.
func (fd *FileDescriptor) fromBytes(buf []byte) error {
func (fd *FileDescriptor) fromBytes(buf []byte) {
if len(buf) != 0x27 {
return fmt.Errorf("FileDescriptor should be 0x27 bytes long; got 0x%02x", len(buf))
panic(fmt.Sprintf("FileDescriptor should be 0x27 bytes long; got 0x%02x", len(buf)))
}
fd.TypeAndNameLength = buf[0]
copyBytes(fd.FileName[:], buf[1:0x10])
fd.FileType = buf[0x10]
fd.KeyPointer = binary.LittleEndian.Uint16(buf[0x11:0x13])
fd.BlocksUsed = binary.LittleEndian.Uint16(buf[0x13:0x15])
copyBytes(fd.Eof[:], buf[0x15:0x18])
if err := fd.Creation.fromBytes(buf[0x18:0x1c]); err != nil {
return fmt.Errorf("unable to unmarshal Creation date/time of FileDescriptor %q: %v", fd.Filename(), err)
}
fd.Creation.fromBytes(buf[0x18:0x1c])
fd.Version = buf[0x1c]
fd.MinVersion = buf[0x1d]
fd.Access = Access(buf[0x1e])
fd.AuxType = binary.LittleEndian.Uint16(buf[0x1f:0x21])
if err := fd.LastMod.fromBytes(buf[0x21:0x25]); err != nil {
return fmt.Errorf("unable to unmarshal last modification date/time of FileDescriptor %q: %v", fd.Filename(), err)
}
fd.LastMod.fromBytes(buf[0x21:0x25])
fd.HeaderPointer = binary.LittleEndian.Uint16(buf[0x25:0x27])
}
return nil
// Validate validates a FileDescriptor for valid values.
func (fd FileDescriptor) Validate() (errors []error) {
errors = append(errors, fd.Creation.Validate(fmt.Sprintf("creation date/time of FileDescriptor %q", fd.Name()))...)
errors = append(errors, fd.LastMod.Validate(fmt.Sprintf("last modification date/time of FileDescriptor %q", fd.Name()))...)
return errors
}
// An index block contains 256 16-bit block numbers, pointing to other
@ -355,6 +380,7 @@ type SubdirectoryKeyBlock struct {
Next uint16 // Pointer to next block in the Volume Directory
Header SubdirectoryHeader
Descriptors [12]FileDescriptor
Extra byte // Trailing byte (so we don't lose it)
}
// ToBlock marshals the SubdirectoryKeyBlock to a Block of bytes.
@ -366,25 +392,34 @@ func (skb SubdirectoryKeyBlock) ToBlock() Block {
for i, desc := range skb.Descriptors {
copyBytes(block[0x2b+i*0x27:0x2b+(i+1)*0x27], desc.toBytes())
}
block[511] = skb.Extra
return block
}
// FromBlock unmarshals a Block of bytes into a SubdirectoryKeyBlock.
func (skb *SubdirectoryKeyBlock) FromBlock(block Block) error {
func (skb *SubdirectoryKeyBlock) FromBlock(block Block) {
skb.Prev = binary.LittleEndian.Uint16(block[0x0:0x2])
if skb.Prev != 0 {
return fmt.Errorf("Subdirectory Key Block should have a `Previous` block of 0, got $%04x", skb.Prev)
}
skb.Next = binary.LittleEndian.Uint16(block[0x2:0x4])
if err := skb.Header.fromBytes(block[0x04:0x2b]); err != nil {
return err
}
skb.Header.fromBytes(block[0x04:0x2b])
for i := range skb.Descriptors {
if err := skb.Descriptors[i].fromBytes(block[0x2b+i*0x27 : 0x2b+(i+1)*0x27]); err != nil {
return fmt.Errorf("cannot deserialize file descriptor %d of Subdirectory Key Block: %v", err)
}
skb.Descriptors[i].fromBytes(block[0x2b+i*0x27 : 0x2b+(i+1)*0x27])
}
return nil
skb.Extra = block[511]
}
// Validate validates a SubdirectoryKeyBlock for valid values.
func (skb SubdirectoryKeyBlock) Validate() (errors []error) {
if skb.Prev != 0 {
errors = append(errors, fmt.Errorf("Subdirectory Key Block should have a `Previous` block of 0, got $%04x", skb.Prev))
}
errors = append(errors, skb.Header.Validate()...)
for _, desc := range skb.Descriptors {
errors = append(errors, desc.Validate()...)
}
if skb.Extra != 0 {
errors = append(errors, fmt.Errorf("Expected last byte of Subdirectory Key Block == 0x0; got 0x%02x", skb.Extra))
}
return errors
}
// SubdirectoryBlock is a normal (non-key) segment in a Subdirectory.
@ -392,6 +427,7 @@ type SubdirectoryBlock struct {
Prev uint16 // Pointer to previous block in the Volume Directory.
Next uint16 // Pointer to next block in the Volume Directory.
Descriptors [13]FileDescriptor
Extra byte // Trailing byte (so we don't lose it)
}
// ToBlock marshals a SubdirectoryBlock to a Block of bytes.
@ -402,19 +438,29 @@ func (sb SubdirectoryBlock) ToBlock() Block {
for i, desc := range sb.Descriptors {
copyBytes(block[0x04+i*0x27:0x04+(i+1)*0x27], desc.toBytes())
}
block[511] = sb.Extra
return block
}
// FromBlock unmarshals a Block of bytes into a SubdirectoryBlock.
func (sb *SubdirectoryBlock) FromBlock(block Block) error {
func (sb *SubdirectoryBlock) FromBlock(block Block) {
sb.Prev = binary.LittleEndian.Uint16(block[0x0:0x2])
sb.Next = binary.LittleEndian.Uint16(block[0x2:0x4])
for i := range sb.Descriptors {
if err := sb.Descriptors[i].fromBytes(block[0x4+i*0x27 : 0x4+(i+1)*0x27]); err != nil {
return fmt.Errorf("cannot deserialize file descriptor %d of Volume Directory Block: %v", err)
}
sb.Descriptors[i].fromBytes(block[0x4+i*0x27 : 0x4+(i+1)*0x27])
}
return nil
sb.Extra = block[511]
}
// Validate validates a SubdirectoryBlock for valid values.
func (sb SubdirectoryBlock) Validate() (errors []error) {
for _, desc := range sb.Descriptors {
errors = append(errors, desc.Validate()...)
}
if sb.Extra != 0 {
errors = append(errors, fmt.Errorf("Expected last byte of Subdirectory Block == 0x0; got 0x%02x", sb.Extra))
}
return errors
}
type SubdirectoryHeader struct {
@ -447,38 +493,46 @@ func (sh SubdirectoryHeader) toBytes() []byte {
buf[0x1e] = byte(sh.Access)
buf[0x1f] = sh.EntryLength
buf[0x20] = sh.EntriesPerBlock
binary.LittleEndian.PutUint16(buf[0x20:0x22], sh.FileCount)
binary.LittleEndian.PutUint16(buf[0x22:0x24], sh.ParentPointer)
buf[0x24] = sh.ParentEntry
buf[0x25] = sh.ParentEntryLength
binary.LittleEndian.PutUint16(buf[0x21:0x23], sh.FileCount)
binary.LittleEndian.PutUint16(buf[0x23:0x25], sh.ParentPointer)
buf[0x25] = sh.ParentEntry
buf[0x26] = sh.ParentEntryLength
return buf
}
// fromBytes unmarshals a slice of bytes into a SubdirectoryHeader.
func (sh *SubdirectoryHeader) fromBytes(buf []byte) error {
func (sh *SubdirectoryHeader) fromBytes(buf []byte) {
if len(buf) != 0x27 {
return fmt.Errorf("VolumeDirectoryHeader should be 0x27 bytes long; got 0x%02x", len(buf))
panic(fmt.Sprintf("VolumeDirectoryHeader should be 0x27 bytes long; got 0x%02x", len(buf)))
}
sh.TypeAndNameLength = buf[0]
copyBytes(sh.SubdirectoryName[:], buf[1:0x10])
if buf[0x10] != 0x75 {
return fmt.Errorf("the byte after subdirectory name should be 0x75; got 0x%02x", buf[0x10])
}
sh.SeventyFive = buf[0x10]
copyBytes(sh.Unused1[:], buf[0x11:0x18])
if err := sh.Creation.fromBytes(buf[0x18:0x1c]); err != nil {
return fmt.Errorf("unable to deserialize Subdirectory Header Creation date/time: %v", err)
}
sh.Creation.fromBytes(buf[0x18:0x1c])
sh.Version = buf[0x1c]
sh.MinVersion = buf[0x1d]
sh.Access = Access(buf[0x1e])
sh.EntryLength = buf[0x1f]
sh.EntriesPerBlock = buf[0x20]
sh.FileCount = binary.LittleEndian.Uint16(buf[0x20:0x22])
sh.ParentPointer = binary.LittleEndian.Uint16(buf[0x22:0x24])
sh.ParentEntry = buf[0x24]
sh.ParentEntryLength = buf[0x25]
return nil
sh.FileCount = binary.LittleEndian.Uint16(buf[0x21:0x23])
sh.ParentPointer = binary.LittleEndian.Uint16(buf[0x23:0x25])
sh.ParentEntry = buf[0x25]
sh.ParentEntryLength = buf[0x26]
}
// Validate validates a SubdirectoryHeader for valid values.
func (sh SubdirectoryHeader) Validate() (errors []error) {
if sh.SeventyFive != 0x75 {
errors = append(errors, fmt.Errorf("Byte after subdirectory name %q should be 0x75; got 0x%02x", sh.Name(), sh.SeventyFive))
}
errors = append(errors, sh.Creation.Validate(fmt.Sprintf("subdirectory %q header creation date/time", sh.Name()))...)
return errors
}
// Name returns the string filename of a subdirectory header.
func (sh SubdirectoryHeader) Name() string {
return string(sh.SubdirectoryName[0 : sh.TypeAndNameLength&0xf])
}
// copyBytes is just like the builtin copy, but just for byte slices,

View File

@ -1 +1,79 @@
package prodos
import (
"crypto/rand"
"strings"
"testing"
"github.com/kr/pretty"
)
func randomBlock() Block {
var b1 Block
rand.Read(b1[:])
return b1
}
// TestVolumeDirectoryKeyBlockMarshalRoundtrip checks a simple roundtrip of VDKB data.
func TestVolumeDirectoryKeyBlockMarshalRoundtrip(t *testing.T) {
b1 := randomBlock()
vdkb := &VolumeDirectoryKeyBlock{}
vdkb.FromBlock(b1)
b2 := vdkb.ToBlock()
if b1 != b2 {
t.Fatalf("Blocks differ: %s", strings.Join(pretty.Diff(b1[:], b2[:]), "; "))
}
vdkb2 := &VolumeDirectoryKeyBlock{}
vdkb2.FromBlock(b2)
if *vdkb != *vdkb2 {
t.Errorf("Structs differ: %v != %v", vdkb, vdkb2)
}
}
// TestVolumeDirectoryBlockMarshalRoundtrip checks a simple roundtrip of VDB data.
func TestVolumeDirectoryBlockMarshalRoundtrip(t *testing.T) {
b1 := randomBlock()
vdb := &VolumeDirectoryBlock{}
vdb.FromBlock(b1)
b2 := vdb.ToBlock()
if b1 != b2 {
t.Fatalf("Blocks differ: %s", strings.Join(pretty.Diff(b1[:], b2[:]), "; "))
}
vdb2 := &VolumeDirectoryBlock{}
vdb2.FromBlock(b2)
if *vdb != *vdb2 {
t.Errorf("Structs differ: %v != %v", vdb, vdb2)
}
}
// TestSubdirectoryKeyBlockMarshalRoundtrip checks a simple roundtrip of SKB data.
func TestSubdirectoryKeyBlockMarshalRoundtrip(t *testing.T) {
b1 := randomBlock()
skb := &SubdirectoryKeyBlock{}
skb.FromBlock(b1)
b2 := skb.ToBlock()
if b1 != b2 {
t.Fatalf("Blocks differ: %s", strings.Join(pretty.Diff(b1[:], b2[:]), "; "))
}
skb2 := &SubdirectoryKeyBlock{}
skb2.FromBlock(b2)
if *skb != *skb2 {
t.Errorf("Structs differ: %v != %v", skb, skb2)
}
}
// TestSubdirectoryBlockMarshalRoundtrip checks a simple roundtrip of SB data.
func TestSubdirectoryBlockMarshalRoundtrip(t *testing.T) {
b1 := randomBlock()
sb := &SubdirectoryBlock{}
sb.FromBlock(b1)
b2 := sb.ToBlock()
if b1 != b2 {
t.Fatalf("Blocks differ: %s", strings.Join(pretty.Diff(b1[:], b2[:]), "; "))
}
sb2 := &SubdirectoryBlock{}
sb2.FromBlock(b2)
if *sb != *sb2 {
t.Errorf("Structs differ: %v != %v", sb, sb2)
}
}