feat(rust): add more details into panic handler

core/embed/rust/src/lib.rs

@@ -19,9 +19,37 @@ mod trezorhal;
 #[macro_use]
 pub mod ui;
 
+#[cfg(feature = "debug")]
+#[panic_handler]
+/// More detailed panic handling. The difference against
+/// default `panic` below is that this "debug" version
+/// takes around 10 kB more space in the flash region.
+fn panic_debug(panic_info: &core::panic::PanicInfo) -> ! {
+    use cstr_core::CStr;
+
+    // SAFETY: Safe because we are passing in \0-terminated literals.
+    let empty = unsafe { CStr::from_bytes_with_nul_unchecked(b"\0") };
+    let msg = unsafe { CStr::from_bytes_with_nul_unchecked(b"rs\0") };
+
+    // Filling at least the file and line information, if available.
+    // TODO: find out how to display message from panic_info.message()
+    if let Some(location) = panic_info.location() {
+        let file = location.file();
+        let line = location.line();
+        let mut file_str = heapless::String::<100>::from(file);
+        file_str.push('\0').unwrap();
+        let file_cstr = unsafe { CStr::from_bytes_with_nul_unchecked(file_str.as_bytes()) };
+        trezorhal::common::fatal_error(empty, msg, file_cstr, line as _, empty);
+    } else {
+        trezorhal::common::fatal_error(empty, msg, empty, 0, empty);
+    }
+}
+
+#[cfg(not(feature = "debug"))]
 #[cfg(not(test))]
 #[cfg(any(not(feature = "test"), feature = "clippy"))]
 #[panic_handler]
+/// Default panic handling. Not showing any details - thus saving flash space.
 fn panic(_info: &core::panic::PanicInfo) -> ! {
     use cstr_core::CStr;
 
@@ -35,7 +63,5 @@ fn panic(_info: &core::panic::PanicInfo) -> ! {
     let empty = unsafe { CStr::from_bytes_with_nul_unchecked(b"\0") };
     let msg = unsafe { CStr::from_bytes_with_nul_unchecked(b"rs\0") };
 
-    // TODO: Ideally we would take the file and line info out of
-    // `PanicInfo::location()`.
     trezorhal::common::fatal_error(empty, msg, empty, 0, empty);
 }