feat: add warning in DOOM for missing wad

kernel/src/Api/BuildNo.hpp

@@ -12,4 +12,4 @@
 
 #pragma once
 
-#define MONTAUK_BUILD_NUMBER 6
+#define MONTAUK_BUILD_NUMBER 7

programs/src/doom/Makefile

@@ -9,9 +9,11 @@ MAKEFLAGS += -rR
 TOOLCHAIN_PREFIX := $(shell cd ../../.. && pwd)/toolchain/local/bin/x86_64-elf-
 ifneq ($(wildcard $(TOOLCHAIN_PREFIX)gcc),)
     CC  := $(TOOLCHAIN_PREFIX)gcc
+    CXX := $(TOOLCHAIN_PREFIX)g++
     LD  := $(TOOLCHAIN_PREFIX)gcc
 else
     CC  := gcc
+    CXX := g++
     LD  := gcc
 endif
 
@@ -21,6 +23,7 @@ DOOM_SRC   := ../../../doomgeneric/doomgeneric
 LIBC_INC   := ../../include/libc
 PROG_INC   := ../../include
 LIBDIR     := ../../lib
+LOADER_LIB := ../../lib/libloader
 LINK_LD    := ../../link.ld
 BINDIR     := ../../bin
 OBJDIR     := obj
@@ -58,6 +61,32 @@ CFLAGS := \
     -I $(DOOM_SRC) \
     -isystem $(shell $(CC) -print-file-name=include)
 
+CXXFLAGS := \
+    -std=gnu++20 \
+    -g -O2 -pipe \
+    -Wall \
+    -Wno-unused-parameter \
+    -nostdinc \
+    -ffreestanding \
+    -fno-stack-protector \
+    -fno-stack-check \
+    -fno-PIC \
+    -fno-rtti \
+    -fno-exceptions \
+    -ffunction-sections \
+    -fdata-sections \
+    -m64 \
+    -march=x86-64 \
+    -msse \
+    -msse2 \
+    -mno-red-zone \
+    -mcmodel=small \
+    -isystem $(LIBC_INC) \
+    -I . \
+    -I $(PROG_INC) \
+    -isystem ../../../kernel/freestnd-c-hdrs/x86_64/include \
+    -isystem ../../../kernel/freestnd-cxx-hdrs/x86_64/include
+
 # ---- Linker flags ----
 
 LDFLAGS := \
@@ -157,12 +186,14 @@ DOOM_SRCS := \
 
 # Local source files
 LOCAL_SRCS     := doomgeneric_montauk.c i_sound_montauk.c
+LOCAL_CXX_SRCS := doom_wad_check.cpp
 
 # ---- Object files ----
 
 DOOM_OBJS     := $(addprefix $(OBJDIR)/,$(DOOM_SRCS:.c=.o))
 LOCAL_OBJS    := $(addprefix $(OBJDIR)/,$(LOCAL_SRCS:.c=.o))
-ALL_OBJS   := $(DOOM_OBJS) $(LOCAL_OBJS)
+LOCAL_CXX_OBJS := $(addprefix $(OBJDIR)/,$(LOCAL_CXX_SRCS:.cpp=.o))
+ALL_OBJS      := $(DOOM_OBJS) $(LOCAL_OBJS) $(LOCAL_CXX_OBJS)
 
 # ---- Target ----
 
@@ -174,7 +205,7 @@ all: $(TARGET)
 
 $(TARGET): $(ALL_OBJS) $(LINK_LD) Makefile
 	mkdir -p $(BINDIR)/apps/doom
-	$(LD) $(CFLAGS) $(LDFLAGS) $(ALL_OBJS) $(LIBDIR)/libc/liblibc.a -o $@
+	$(LD) $(CFLAGS) $(LDFLAGS) $(ALL_OBJS) $(LOADER_LIB)/liblibloader.a $(LIBDIR)/libc/liblibc.a -o $@
 
 # DOOM source files (from doomgeneric directory)
 $(OBJDIR)/%.o: $(DOOM_SRC)/%.c Makefile
@@ -186,6 +217,11 @@ $(OBJDIR)/%.o: %.c Makefile
 	mkdir -p $(OBJDIR)
 	$(CC) $(CFLAGS) -MMD -MP -c $< -o $@
 
+# Local C++ source files
+$(OBJDIR)/%.o: %.cpp Makefile
+	mkdir -p $(OBJDIR)
+	$(CXX) $(CXXFLAGS) -MMD -MP -c $< -o $@
+
 clean:
 	rm -rf $(OBJDIR) $(TARGET)
 

programs/src/doom/doom_wad_check.cpp

@@ -0,0 +1,22 @@
+/*
+    * doom_wad_check.cpp
+    * Warns the user and exits cleanly if no DOOM WAD is present
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#include <gui/dialogs.hpp>
+#include <montauk/syscall.h>
+#include <stdio.h>
+
+extern "C" [[noreturn]] void doom_warn_missing_wad(const char* path) {
+    char message[400];
+    snprintf(message, sizeof(message),
+        "No DOOM WAD file was found at %s.\n\n"
+        "MontaukOS cannot ship proprietary DOOM WADs (doom1.wad, doom.wad, "
+        "freedoom1.wad, etc.) on its ISO images due to copyright restrictions.\n\n"
+        "Copy a legally obtained WAD file to that path and relaunch DOOM.",
+        path);
+
+    gui::dialogs::message_box("DOOM", message, gui::dialogs::MESSAGE_BOX_OK);
+    montauk::exit(1);
+}

programs/src/doom/doomgeneric_montauk.c

@@ -246,8 +246,22 @@ void DG_SetWindowTitle(const char* title) {
 
 /* ---- Entry point ---- */
 
+/* Shows a warning dialog explaining that MontaukOS cannot ship proprietary
+ * DOOM WADs and does not return (implemented in doom_wad_check.cpp, which
+ * links against the shared dialog library). */
+extern void doom_warn_missing_wad(const char* path);
+
 void _start(void) {
-    char *argv[] = { "doom", "-iwad", "0:/apps/doom/doom1.wad", 0 };
+    static const char* wadPath = "0:/apps/doom/doom1.wad";
+
+    FILE* wad = fopen(wadPath, "rb");
+    if (!wad) {
+        doom_warn_missing_wad(wadPath);
+        /* unreachable: doom_warn_missing_wad() exits the process */
+    }
+    fclose(wad);
+
+    char *argv[] = { "doom", "-iwad", (char*)wadPath, 0 };
     doomgeneric_Create(3, argv);
     for (;;) {
         doomgeneric_Tick();