Add stubbed-out delete, supermon symbol encoding

cmd/delete.go

@@ -0,0 +1,68 @@
+// Copyright © 2016 Zellyn Hunter <[email protected]>
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+	"github.com/zellyn/diskii/lib/disk"
+	_ "github.com/zellyn/diskii/lib/dos3"
+	_ "github.com/zellyn/diskii/lib/supermon"
+)
+
+// deleteCmd represents the delete command, used to delete a file.
+var deleteCmd = &cobra.Command{
+	Use:   "delete",
+	Short: "delete a file",
+	Long: `Delete a file.
+
+delete disk-image.dsk HELLO
+`,
+	Run: func(cmd *cobra.Command, args []string) {
+		if err := runDelete(args); err != nil {
+			fmt.Fprintln(os.Stderr, err.Error())
+			os.Exit(-1)
+		}
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(deleteCmd)
+}
+
+// runDelete performs the actual delete logic.
+func runDelete(args []string) error {
+	if len(args) != 2 {
+		return fmt.Errorf("delete expects a disk image filename, and a filename")
+	}
+	sd, err := disk.Open(args[0])
+	if err != nil {
+		return err
+	}
+	op, err := disk.OperatorFor(sd)
+	if err != nil {
+		return err
+	}
+	deleted, err := op.Delete(args[1])
+	if err != nil {
+		return err
+	}
+	if !deleted {
+		// TODO(zellyn): implement -f flag to not warn on nonexistence.
+		return fmt.Errorf("file %q not found", args[1])
+	}
+	f, err := os.Create(args[0])
+	if err != nil {
+		return err
+	}
+	_, err = sd.Write(f)
+	if err != nil {
+		return err
+	}
+	if err = f.Close(); err != nil {
+		return err
+	}
+	return nil
+}

lib/disk/disk.go

@@ -6,6 +6,7 @@ package disk
 
 import (
 	"fmt"
+	"io"
 	"path"
 	"strings"
 )
@@ -49,6 +50,8 @@ type SectorDisk interface {
 	Sectors() byte
 	// Tracks returns the number of tracks on the SectorDisk
 	Tracks() byte
+	// Write writes the disk contents to the given file.
+	Write(io.Writer) (int, error)
 }
 
 type LogicalSectorDisk interface {
@@ -62,6 +65,8 @@ type LogicalSectorDisk interface {
 	Sectors() byte
 	// Tracks returns the number of tracks on the SectorDisk
 	Tracks() byte
+	// Write writes the disk contents to the given file.
+	Write(io.Writer) (int, error)
 }
 
 // MappedDisk wraps a SectorDisk as a LogicalSectorDisk, handling the
@@ -125,6 +130,11 @@ func (md MappedDisk) Tracks() byte {
 	return md.sectorDisk.Tracks()
 }
 
+// Write writes the disk contents to the given file.
+func (md MappedDisk) Write(w io.Writer) (n int, err error) {
+	return md.sectorDisk.Write(w)
+}
+
 // Open opens a disk image by filename.
 func Open(filename string) (SectorDisk, error) {
 	ext := strings.ToLower(path.Ext(filename))

lib/disk/dsk.go

@@ -6,6 +6,7 @@ package disk
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 )
 
@@ -84,3 +85,8 @@ func (d DSK) Sectors() byte {
 func (d DSK) Tracks() byte {
 	return d.tracks
 }
+
+// Write writes the disk contents to the given file.
+func (d DSK) Write(w io.Writer) (n int, err error) {
+	return w.Write(d.data)
+}

lib/disk/ops.go

@@ -83,6 +83,9 @@ type Operator interface {
 	Catalog(subdir string) ([]Descriptor, error)
 	// GetFile retrieves a file by name.
 	GetFile(filename string) (FileInfo, error)
+	// Delete deletes a file by name. It returns true if the file was
+	// deleted, false if it didn't exist.
+	Delete(filename string) (bool, error)
 }
 
 // FileInfo represents a file descriptor plus the content.

lib/dos3/dos3.go

@@ -651,6 +651,12 @@ func (o operator) GetFile(filename string) (disk.FileInfo, error) {
 	return disk.FileInfo{}, fmt.Errorf("%s does not yet implement `GetFile` for filetype %s", operatorName, errType)
 }
 
+// Delete deletes a file by name. It returns true if the file was
+// deleted, false if it didn't exist.
+func (o operator) Delete(filename string) (bool, error) {
+	return false, fmt.Errorf("%s does not implement Delete yet", operatorName)
+}
+
 // operatorFactory is the factory that returns dos3 operators given
 // disk images.
 func operatorFactory(sd disk.SectorDisk) (disk.Operator, error) {

lib/supermon/supermon.go

@@ -4,9 +4,8 @@
 // structures of NakedOS/Super-Mon disks.
 package supermon
 
-// TODO(zellyn): remove panics.
-
 import (
+	"encoding/binary"
 	"fmt"
 	"strconv"
 	"strings"
@@ -152,6 +151,44 @@ func decodeSymbol(five []byte, extra byte) string {
 	return result
 }
 
+// encodeSymbol encodes a symbol name into the five+1 bytes used in a
+// Super-Mon encoded symbol table entry. The returned byte array will
+// always be six bytes long. If it can't be encoded, it returns an
+// error.
+func encodeSymbol(name string) (six []byte, err error) {
+	if len(name) > 9 {
+		return nil, fmt.Errorf("invalid Super-Mon symbol %q: too long", name)
+	}
+	if len(name) < 3 {
+		return nil, fmt.Errorf("invalid Super-Mon symbol %q: too short", name)
+	}
+	nm := []byte(strings.ToUpper(name))
+	value := uint64(0)
+	bits := 0
+	for i := len(nm) - 1; i >= 0; i-- {
+		ch := nm[i]
+		switch {
+		case 'A' <= ch && ch <= 'Z':
+			value = value<<5 + uint64(ch-'@')
+			bits += 5
+		case '0' <= ch && ch <= '4':
+			value = value<<6 + 0x1b + uint64(ch-'0')
+			bits += 6
+		case '5' <= ch && ch <= '9':
+			value = value<<6 + 0x3b + uint64(ch-'5')
+			bits += 6
+		}
+		if bits > 48 {
+			return nil, fmt.Errorf("invalid Super-Mon symbol %q: too long", name)
+		}
+	}
+	eight := make([]byte, 8)
+	six = make([]byte, 6)
+	binary.LittleEndian.PutUint64(eight, value)
+	copy(six, eight)
+	return six, nil
+}
+
 // SymbolTable represents an entire Super-Mon symbol table. It'll
 // always be 819 entries long, because it includes blanks.
 type SymbolTable []Symbol
@@ -192,7 +229,7 @@ func (sm SectorMap) ReadSymbolTable(sd disk.SectorDisk) (SymbolTable, error) {
 			if (linkAddr-0xD000)%5 != 0 {
 				return nil, fmt.Errorf("Expected symbol table link address to 0xD000+5x; got 0x%04X", linkAddr)
 			}
-			link = (int(linkAddr) - 0xD000) % 5
+			link = (int(linkAddr) - 0xD000) / 5
 		}
 		extra := symtbl1[i+4]
 		copy(five, symtbl2[i:i+5])
@@ -205,11 +242,27 @@ func (sm SectorMap) ReadSymbolTable(sd disk.SectorDisk) (SymbolTable, error) {
 		table = append(table, symbol)
 	}
 
-	// TODO(zellyn): check link addresses.
+	for i, sym := range table {
+		if sym.Address != 0 && sym.Link != -1 {
+			if sym.Link == i {
+				return nil, fmt.Errorf("Symbol %q (0x%04X) links to itself", sym.Name, sym.Address)
+			}
+			linkSym := table[sym.Link]
+			if addrHash(sym.Address) != addrHash(linkSym.Address) {
+				return nil, fmt.Errorf("Symbol %q (0x%04X) with hash 0x%02X links to symbol %q (0x%04X) with hash 0x%02X",
+					sym.Name, sym.Address, addrHash(sym.Address), linkSym.Name, linkSym.Address, addrHash(linkSym.Address))
+			}
+		}
+	}
 
 	return table, nil
 }
 
+// addrHash computes the SuperMon hash for an address.
+func addrHash(addr uint16) byte {
+	return (byte(addr) ^ byte(addr>>8)) & 0x7f
+}
+
 // SymbolsByAddress returns a map of addresses to slices of symbols.
 func (st SymbolTable) SymbolsByAddress() map[uint16][]Symbol {
 	result := map[uint16][]Symbol{}
@@ -319,12 +372,21 @@ func (o operator) GetFile(filename string) (disk.FileInfo, error) {
 		Length:  len(data),
 		Locked:  false,
 		Type:    disk.FiletypeBinary,
-		// TODO(zellyn): Set StartAddress if we know it.
 	}
-	return disk.FileInfo{
+	fi := disk.FileInfo{
 		Descriptor: desc,
 		Data:       data,
-	}, nil
+	}
+	if file == 1 {
+		fi.StartAddress = 0x1800
+	}
+	return fi, nil
+}
+
+// Delete deletes a file by name. It returns true if the file was
+// deleted, false if it didn't exist.
+func (o operator) Delete(filename string) (bool, error) {
+	return false, fmt.Errorf("%s does not implement Delete yet", operatorName)
 }
 
 // operatorFactory is the factory that returns supermon operators

lib/supermon/supermon_test.go

@@ -3,6 +3,7 @@
 package supermon
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/zellyn/diskii/lib/disk"
@@ -137,3 +138,43 @@ No more; and by a sleep, to say we end
 		t.Errorf("Incorrect result for GetFile(\"TOBE\"): want %q; got %q", want, got)
 	}
 }
+
+// TestEncodeDecode tests encoding and decoding of Super-Mon symbol
+// table entries.
+func TestEncodeDecode(t *testing.T) {
+	testdata := []struct {
+		sym   string
+		valid bool
+	}{
+		{"ABC", true},
+		{"abc", true},
+		{"ABCDEFGHI", true},
+		{"abcdefghi", true},
+		{"ABCDEF123", true},
+		{"abcdef123", true},
+
+		{"AB", false},
+		{"ab", false},
+		{"ABCDE1234", false},
+		{"abcde1234", false},
+	}
+
+	for _, tt := range testdata {
+		if !tt.valid {
+			if _, err := encodeSymbol(tt.sym); err == nil {
+				t.Errorf("Expected symbol %q to be invalid, but wansn't", tt.sym)
+			}
+			continue
+		}
+
+		bytes, err := encodeSymbol(tt.sym)
+		if err != nil {
+			t.Errorf("Unexpected error encoding symbol %q", tt.sym)
+			continue
+		}
+		sym := decodeSymbol(bytes[:5], bytes[5])
+		if sym != strings.ToUpper(tt.sym) {
+			t.Errorf("Symbol %q encodes to %q", tt.sym, sym)
+		}
+	}
+}