fail gracefully when ROM loading fails

src/NDS.cpp

@@ -352,14 +352,18 @@ void Stop()
     SPU::Stop();
 }
 
-void LoadROM(const char* path, bool direct)
+bool LoadROM(const char* path, bool direct)
 {
-    Reset();
-
     if (NDSCart::LoadROM(path, direct))
+    {
         Running = true;
+        return true;
+    }
     else
+    {
         printf("Failed to load ROM %s\n", path);
+        return false;
+    }
 }
 
 void LoadBIOS()

src/NDS.h

@@ -106,7 +106,7 @@ void DeInit();
 void Reset();
 void Stop();
 
-void LoadROM(const char* path, bool direct);
+bool LoadROM(const char* path, bool direct);
 void LoadBIOS();
 void SetupDirectBoot();
 

src/NDSCart.cpp

@@ -817,15 +817,14 @@ bool LoadROM(const char* path, bool direct)
     // TODO: streaming mode? for really big ROMs or systems with limited RAM
     // for now we're lazy
 
-    if (CartROM) delete[] CartROM;
-
     FILE* f = fopen(path, "rb");
     if (!f)
     {
-        printf("Failed to open ROM file %s\n", path);
         return false;
     }
 
+    NDS::Reset();
+
     fseek(f, 0, SEEK_END);
     u32 len = (u32)ftell(f);
 
@@ -845,6 +844,11 @@ bool LoadROM(const char* path, bool direct)
     fclose(f);
     //CartROM = f;
 
+    // generate a ROM ID
+    // note: most games don't check the actual value
+    // it just has to stay the same throughout gameplay
+    CartID = 0x00001FC2;
+
     if (direct)
     {
         NDS::SetupDirectBoot();
@@ -853,11 +857,6 @@ bool LoadROM(const char* path, bool direct)
 
     CartInserted = true;
 
-    // generate a ROM ID
-    // note: most games don't check the actual value
-    // it just has to stay the same throughout gameplay
-    CartID = 0x00001FC2;
-
     u32 arm9base = *(u32*)&CartROM[0x20];
     if (arm9base < 0x8000)
     {

src/libui_sdl/main.cpp

@@ -400,6 +400,27 @@ void Stop(bool internal)
     uiAreaQueueRedrawAll(MainDrawArea);
 }
 
+void TryLoadROM(char* file, int prevstatus)
+{
+    char oldpath[1024];
+    strncpy(oldpath, ROMPath, 1024);
+
+    strncpy(ROMPath, file, 1023);
+    ROMPath[1023] = '\0';
+
+    if (NDS::LoadROM(ROMPath, Config::DirectBoot))
+        Run();
+    else
+    {
+        uiMsgBoxError(MainWindow,
+                      "Failed to load the ROM",
+                      "Make sure the file can be accessed and isn't opened in another application.");
+
+        strncpy(ROMPath, oldpath, 1024);
+        EmuRunning = prevstatus;
+    }
+}
+
 
 int OnCloseWindow(uiWindow* window, void* blarg)
 {
@@ -410,6 +431,7 @@ int OnCloseWindow(uiWindow* window, void* blarg)
 void OnDropFile(uiWindow* window, char* file, void* blarg)
 {
     char* ext = &file[strlen(file)-3];
+    int prevstatus = EmuRunning;
 
     if (!strcasecmp(ext, "nds") || !strcasecmp(ext, "srl"))
     {
@@ -419,11 +441,7 @@ void OnDropFile(uiWindow* window, char* file, void* blarg)
             while (EmuStatus != 2);
         }
 
-        strncpy(ROMPath, file, 1023);
+        TryLoadROM(file, prevstatus);
-        ROMPath[1023] = '\0';
-
-        NDS::LoadROM(ROMPath, Config::DirectBoot);
-        Run();
     }
 }
 
@@ -456,14 +474,8 @@ void OnOpenFile(uiMenuItem* item, uiWindow* window, void* blarg)
         return;
     }
 
-    strncpy(ROMPath, file, 1023);
+    TryLoadROM(file, prevstatus);
-    ROMPath[1023] = '\0';
     uiFreeText(file);
-    // TODO: change libui to store strings in stack-allocated buffers?
-    // so we don't have to free it after use
-
-    NDS::LoadROM(ROMPath, Config::DirectBoot);
-    Run();
 }
 
 void OnRun(uiMenuItem* item, uiWindow* window, void* blarg)
@@ -685,8 +697,8 @@ int main(int argc, char** argv)
             strncpy(ROMPath, file, 1023);
             ROMPath[1023] = '\0';
 
-            NDS::LoadROM(ROMPath, Config::DirectBoot);
+            if (NDS::LoadROM(ROMPath, Config::DirectBoot))
-            Run();
+                Run();
         }
     }