ELF file loaded with undefined symbols generates a notification

debugger/debugger.go

@@ -1131,6 +1131,11 @@ func (dbg *Debugger) Notify(notice notifications.Notice) error {
 		if err != nil {
 			return err
 		}
+	case notifications.NotifyElfUndefinedSymbols:
+		err := dbg.gui.SetFeature(gui.ReqNotification, notifications.NotifyElfUndefinedSymbols)
+		if err != nil {
+			return err
+		}
 	case notifications.NotifyMovieCartStarted:
 		return dbg.vcs.TV.Reset(true)
 	default:

gui/sdlimgui/modal.go

@@ -15,12 +15,17 @@
 
 package sdlimgui
 
+import (
+	"github.com/inkyblackness/imgui-go/v4"
+)
+
 type modal int
 
 const (
 	modalNone modal = iota
 	modalPlusROMFirstInstallation
 	modalUnsupportedDWARF
+	modalElfUndefinedSymbols
 )
 
 func (img *SdlImgui) modalDraw() {
@@ -29,9 +34,47 @@ func (img *SdlImgui) modalDraw() {
 		img.modalDrawPlusROMFirstInstallation()
 	case modalUnsupportedDWARF:
 		img.modalDrawUnsupportedDWARF()
+	case modalElfUndefinedSymbols:
+		img.modalElfUndefinedSymbols()
 	}
 }
 
 func (img *SdlImgui) modalActive() bool {
 	return img.modal != modalNone
 }
+
+func (img *SdlImgui) modalElfUndefinedSymbols() {
+	const popupTitle = "Undefined Symbols in ELF file"
+
+	imgui.OpenPopup(popupTitle)
+	flgs := imgui.WindowFlagsAlwaysAutoResize
+	flgs |= imgui.WindowFlagsNoMove
+	flgs |= imgui.WindowFlagsNoSavedSettings
+	if imgui.BeginPopupModalV(popupTitle, nil, flgs) {
+		imgui.Text("The ELF ROM contains an undefined symbol. Rather than aborting")
+		imgui.Text("the loading process the symbol has been linked to the undefined")
+		imgui.Text("symbol handler")
+		imgui.Spacing()
+		imgui.Spacing()
+		imgui.Text("The ROM will progress as expected until the symbol is accessed")
+		imgui.Spacing()
+		imgui.Spacing()
+		imgui.Text("If the symbol is accessed during execution a memory fault will")
+		imgui.Text("be generated")
+
+		imgui.Spacing()
+		imgui.Separator()
+		imgui.Spacing()
+
+		sz := imgui.ContentRegionAvail()
+		sz.Y = img.fonts.guiSize
+		sz.Y += imgui.CurrentStyle().CellPadding().Y * 2
+		sz.Y += imgui.CurrentStyle().FramePadding().Y * 2
+		if imgui.ButtonV("Continue with undefined function handler", sz) {
+			imgui.CloseCurrentPopup()
+			img.modal = modalNone
+		}
+
+		imgui.EndPopup()
+	}
+}

gui/sdlimgui/requests.go

@@ -83,6 +83,8 @@ func (img *SdlImgui) serviceSetFeature(request featureRequest) {
 				img.modal = modalPlusROMFirstInstallation
 			case notifications.NotifyUnsupportedDWARF:
 				img.modal = modalUnsupportedDWARF
+			case notifications.NotifyElfUndefinedSymbols:
+				img.modal = modalElfUndefinedSymbols
 			default:
 				img.playScr.overlay.set(request.args[0].(notifications.Notice))
 			}

hardware/memory/cartridge/elf/elf.go

@@ -29,6 +29,7 @@ import (
 	"github.com/jetsetilly/gopher2600/hardware/memory/cartridge/mapper"
 	"github.com/jetsetilly/gopher2600/hardware/memory/cpubus"
 	"github.com/jetsetilly/gopher2600/hardware/memory/memorymap"
+	"github.com/jetsetilly/gopher2600/notifications"
 )
 
 // Elf implements the mapper.CartMapper interface.
@@ -155,6 +156,11 @@ func NewElf(env *environment.Environment, loader cartridgeloader.Loader, inACE b
 		return nil, fmt.Errorf("ELF: %w", err)
 	}
 
+	// notify emulator that some symbols in the ELF have
+	if cart.mem.unresolvedSymbols {
+		cart.env.Notifications.Notify(notifications.NotifyElfUndefinedSymbols)
+	}
+
 	return cart, nil
 }
 

hardware/memory/cartridge/elf/memory.go

@@ -118,6 +118,10 @@ type elfMemory struct {
 
 	symbols []elf.Symbol
 
+	// this field will be true if some symbols could not be completely resolved
+	// during loading
+	unresolvedSymbols bool
+
 	// strongARM support. like the elf sections, the strongARM program is placed
 	// in flash memory
 	strongArmProgram   []byte
@@ -530,6 +534,9 @@ func (mem *elfMemory) decode(ef *elf.File) error {
 							},
 							support: true,
 						})
+
+						// flag presence of unresolved symbols
+						mem.unresolvedSymbols = true
 					} else {
 						n := ef.Sections[sym.Section].Name
 						if idx, ok := mem.sectionsByName[n]; !ok {

notifications/notifications.go

@@ -38,6 +38,9 @@ const (
 	NotifyPlusROMNewInstall Notice = "NotifyPlusROMNewInstall"
 	NotifyPlusROMNetwork    Notice = "NotifyPlusROMNetwork"
 
+	// notifications sent by ELF cartridges
+	NotifyElfUndefinedSymbols Notice = "NotifyElfUndefinedSymbols"
+
 	// moviecart has started
 	NotifyMovieCartStarted Notice = "NotifyMoveCartStarted"