Add error applet support + error applet panic hook

ctru-rs/src/applets/error.rs

@@ -0,0 +1,56 @@
+//! Error applet
+//!
+//! This applet displays error text as a pop-up message on the lower screen.
+#![doc(alias = "Error")]
+
+use crate::services::{apt::Apt, gfx::Gfx};
+
+use ctru_sys::errorConf;
+
+/// Configuration struct to set up the Error applet.
+#[doc(alias = "errorConf")]
+pub struct ErrorApplet {
+    state: Box<errorConf>,
+}
+
+/// The kind of error applet to display.
+#[doc(alias = "errorType")]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[repr(u32)]
+pub enum Kind {
+    /// Error text is centered in the error applet window.
+    Center = ctru_sys::ERROR_TEXT,
+    /// Error text starts at the top of the error applet window.
+    Top = ctru_sys::ERROR_TEXT_WORD_WRAP,
+}
+
+impl ErrorApplet {
+    /// Initialize the error applet with the provided text kind.
+    #[doc(alias = "errorInit")]
+    pub fn new(kind: Kind) -> Self {
+        let mut state = Box::<errorConf>::default();
+
+        unsafe { ctru_sys::errorInit(state.as_mut(), kind as _, 0) };
+
+        Self { state }
+    }
+
+    /// Sets the error text to display.
+    #[doc(alias = "errorText")]
+    pub fn set_text(&mut self, text: &str) {
+        for (idx, code_unit) in text
+            .encode_utf16()
+            .chain(std::iter::once(0))
+            .take(self.state.Text.len() - 1)
+            .enumerate()
+        {
+            self.state.Text[idx] = code_unit;
+        }
+    }
+
+    /// Launches the error applet.
+    #[doc(alias = "errorDisp")]
+    pub fn launch(&mut self, _apt: &Apt, _gfx: &Gfx) {
+        unsafe { ctru_sys::errorDisp(self.state.as_mut()) }
+    }
+}

ctru-rs/src/applets/mod.rs

@@ -8,5 +8,6 @@
 //!
 //! Applets block execution of the thread that launches them as long as the user doesn't close the applet.
 
+pub mod error;
 pub mod mii_selector;
 pub mod swkbd;

ctru-sys/build.rs

@@ -79,6 +79,8 @@ fn main() {
         .blocklist_type("u(8|16|32|64)")
         .blocklist_type("__builtin_va_list")
         .blocklist_type("__va_list")
+        .blocklist_type("errorReturnCode")
+        .blocklist_type("errorScreenFlag")
         .opaque_type("MiiData")
         .derive_default(true)
         .wrap_static_fns(true)

ctru-sys/src/lib.rs

@@ -16,6 +16,24 @@
 pub mod result;
 pub use result::*;
 
+// Fun fact: C compilers are allowed to represent enums as the smallest integer type that can hold all of its variants,
+// meaning that enums are allowed to be the size of a `c_short` or a `c_char` rather than the size of a `c_int`.
+// Libctru's `errorConf` struct contains two enums that depend on this narrowing property for size and alignment purposes,
+// and since `bindgen` generates all enums with `c_int` sizing, we have to blocklist those types and manually define them
+// here with the proper size.
+pub const ERROR_UNKNOWN: errorReturnCode = -1;
+pub const ERROR_NONE: errorReturnCode = 0;
+pub const ERROR_SUCCESS: errorReturnCode = 1;
+pub const ERROR_NOT_SUPPORTED: errorReturnCode = 2;
+pub const ERROR_HOME_BUTTON: errorReturnCode = 10;
+pub const ERROR_SOFTWARE_RESET: errorReturnCode = 11;
+pub const ERROR_POWER_BUTTON: errorReturnCode = 12;
+pub type errorReturnCode = libc::c_schar;
+
+pub const ERROR_NORMAL: errorScreenFlag = 0;
+pub const ERROR_STEREO: errorScreenFlag = 1;
+pub type errorScreenFlag = libc::c_char;
+
 include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 
 /// In lieu of a proper errno function exposed by libc