playback files no longer created cartridge loader directly

the information used to create the loader is storied in
the playback type rather than a created loader itself

this is more flexible and gives us better control of when
the loader is disposed of

checking of cartridge hash must now be performed explicitely
when the cartridge loader is created from the playback information

debugger/debugger.go

@@ -836,7 +836,10 @@ func (dbg *Debugger) StartInPlayMode(filename string) error {
 			return fmt.Errorf("debugger: cannot make a new recording using a playback file")
 		}
 
-		dbg.startPlayback(filename)
+		err = dbg.startPlayback(filename)
+		if err != nil {
+			return fmt.Errorf("debugger: %w", err)
+		}
 	}
 
 	if dbg.opts.Macro != "" {
@@ -1289,12 +1292,26 @@ func (dbg *Debugger) endRecording() {
 }
 
 func (dbg *Debugger) startPlayback(filename string) error {
-	plb, err := recorder.NewPlayback(filename, dbg.opts.PlaybackCheckROM)
+	plb, err := recorder.NewPlayback(filename)
 	if err != nil {
 		return err
 	}
 
-	err = dbg.attachCartridge(plb.CartLoad)
+	// new cartridge loader using the information found in the playback file
+	cartload, err := cartridgeloader.NewLoaderFromFilename(plb.Cartridge, "AUTO")
+	if err != nil {
+		return fmt.Errorf("debugger: %w", err)
+	}
+	defer cartload.Close()
+
+	// check hash of cartridge before continuing
+	if dbg.opts.PlaybackCheckROM && cartload.HashSHA1 != plb.Hash {
+		return fmt.Errorf("playback: unexpected hash")
+	}
+
+	// cartload is should be passed to attachCartridge() almost immediately. the
+	// closure of cartload will then be handled for us
+	err = dbg.attachCartridge(cartload)
 	if err != nil {
 		return err
 	}

recorder/fileformat.go

@@ -22,8 +22,6 @@ import (
 	"io"
 	"os"
 	"strings"
-
-	"github.com/jetsetilly/gopher2600/cartridgeloader"
 )
 
 const (
@@ -104,22 +102,13 @@ func (rec *Recorder) writeHeader() error {
 	return nil
 }
 
-func (plb *Playback) readHeader(lines []string, checkROM bool) error {
+func (plb *Playback) readHeader(lines []string) error {
 	if lines[lineMagicString] != magicString {
 		return fmt.Errorf("playback: not a valid transcript (%s)", plb.transcript)
 	}
 
-	var err error
-
-	plb.CartLoad, err = cartridgeloader.NewLoaderFromFilename(lines[lineCartName], "AUTO")
-	if err != nil {
-		return fmt.Errorf("playback: %w", err)
-	}
-
-	if checkROM && plb.CartLoad.HashSHA1 != lines[lineCartHash] {
-		return fmt.Errorf("playback: unexpected hash")
-	}
-
+	plb.Cartridge = lines[lineCartName]
+	plb.Hash = lines[lineCartHash]
 	plb.TVSpec = lines[lineTVSpec]
 
 	return nil

recorder/playback.go

@@ -23,7 +23,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/jetsetilly/gopher2600/cartridgeloader"
 	"github.com/jetsetilly/gopher2600/digest"
 	"github.com/jetsetilly/gopher2600/hardware"
 	"github.com/jetsetilly/gopher2600/hardware/riot/ports"
@@ -44,8 +43,9 @@ type playbackEntry struct {
 type Playback struct {
 	transcript string
 
-	CartLoad cartridgeloader.Loader
-	TVSpec   string
+	Cartridge string
+	Hash      string
+	TVSpec    string
 
 	sequence []playbackEntry
 	seqCt    int
@@ -79,7 +79,7 @@ func (plb Playback) EndFrame() (bool, error) {
 // AttachToVCSInput() function) for it it to be useful.
 //
 // The integrityCheck flag should be true in most instances.
-func NewPlayback(transcript string, checkROM bool) (*Playback, error) {
+func NewPlayback(transcript string) (*Playback, error) {
 	var err error
 
 	plb := &Playback{
@@ -104,7 +104,7 @@ func NewPlayback(transcript string, checkROM bool) (*Playback, error) {
 	lines := strings.Split(string(buffer), "\n")
 
 	// read header and perform validation checks
-	err = plb.readHeader(lines, checkROM)
+	err = plb.readHeader(lines)
 	if err != nil {
 		return nil, err
 	}

regression/playback.go

@@ -24,6 +24,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/jetsetilly/gopher2600/cartridgeloader"
 	"github.com/jetsetilly/gopher2600/database"
 	"github.com/jetsetilly/gopher2600/debugger/govern"
 	"github.com/jetsetilly/gopher2600/digest"
@@ -105,7 +106,7 @@ func (reg PlaybackRegression) String() string {
 func (reg *PlaybackRegression) regress(newRegression bool, output io.Writer, msg string) (_ bool, _ string, rerr error) {
 	output.Write([]byte(msg))
 
-	plb, err := recorder.NewPlayback(reg.Script, true)
+	plb, err := recorder.NewPlayback(reg.Script)
 	if err != nil {
 		return false, "", fmt.Errorf("playback: %w", err)
 	}
@@ -137,10 +138,22 @@ func (reg *PlaybackRegression) regress(newRegression bool, output io.Writer, msg
 		return false, "", fmt.Errorf("playback: %w", err)
 	}
 
+	// new cartridge loader using the information found in the playback file
+	cartload, err := cartridgeloader.NewLoaderFromFilename(plb.Cartridge, "AUTO")
+	if err != nil {
+		return false, "", fmt.Errorf("playback: %w", err)
+	}
+	defer cartload.Close()
+
+	// check hash of cartridge before continuing
+	if cartload.HashSHA1 != plb.Hash {
+		return false, "", fmt.Errorf("playback: unexpected hash")
+	}
+
 	// not using setup.AttachCartridge. if the playback was recorded with setup
 	// changes the events will have been copied into the playback script and
 	// will be applied that way
-	err = vcs.AttachCartridge(plb.CartLoad, true)
+	err = vcs.AttachCartridge(cartload, true)
 	if err != nil {
 		return false, "", fmt.Errorf("playback: %w", err)
 	}
@@ -191,7 +204,7 @@ func (reg *PlaybackRegression) regress(newRegression bool, output io.Writer, msg
 	// regressionScripts directory
 	if newRegression {
 		// create a unique filename
-		newScript, err := uniqueFilename("playback", plb.CartLoad.Name)
+		newScript, err := uniqueFilename("playback", cartload.Name)
 		if err != nil {
 			return false, "", fmt.Errorf("playback: %w", err)
 		}