Add back Console::drop

ctru-rs/Cargo.toml

@@ -12,6 +12,7 @@ name = "ctru"
 
 [dependencies]
 ctru-sys = { path = "../ctru-sys", version = "0.4" }
+const-zero = "0.1.0"
 linker-fix-3ds = { git = "https://github.com/Meziu/rust-linker-fix-3ds.git" }
 pthread-3ds = { git = "https://github.com/Meziu/pthread-3ds.git" }
 libc = { git = "https://github.com/Meziu/libc.git" }

ctru-rs/src/console.rs

@@ -50,3 +50,31 @@ impl Default for Console {
         Console::init(Screen::Top)
     }
 }
+
+impl Drop for Console {
+    fn drop(&mut self) {
+        static mut EMPTY_CONSOLE: PrintConsole = unsafe { const_zero::const_zero!(PrintConsole) };
+
+        unsafe {
+            // Safety: We are about to deallocate the PrintConsole data pointed
+            // to by libctru. Without this drop code libctru would have a
+            // dangling pointer that it writes to on every print. To prevent
+            // this we replace the console with an empty one if it was selected.
+            // This is the same state that libctru starts up in, before
+            // initializing a console. Writes to the console will not show up on
+            // the screen, but it won't crash either.
+
+            // Get the current console by replacing it with an empty one.
+            let current_console = ctru_sys::consoleSelect(&mut EMPTY_CONSOLE);
+
+            if std::ptr::eq(current_console, &*self.context) {
+                // Console dropped while selected. We just replaced it with the
+                // empty console so nothing more to do.
+            } else {
+                // Console dropped while a different console was selected. Put back
+                // the console that was selected.
+                ctru_sys::consoleSelect(current_console);
+            }
+        }
+    }
+}