Fix display of panic message

When connected via USB serial, there is often not enough time
for the output to be fully recieved before the USB device resets.

Add a short 500 ms delay before we call `furi_crash`.

This also fixes incorrect `printf` formatting strings with explicit
length (the length is provided as the 'precision' value after the decimal
rather than the 'width' value before the decimal).

CHANGELOG.md

@@ -19,6 +19,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - Fixed passing of crash message `__furi_crash_implementation`
 - Allow no argument calls to `flipperzero_sys::crash!` and `flipperzero_sys::halt!` macros
 - `flipperzero_sys::furi::UnsafeRecord::open` now takes a `&'static CStr`
+- Fixed overread when printing panic message to console
+- Added short delay in panic handler so message can be seen on USB console before `furi_crash`
 
 ### Removed
 

crates/rt/src/panic_handler.rs

@@ -1,7 +1,6 @@
 //! Panic handler for Furi applications.
 //! This will print the panic info to stdout and then trigger a crash.
 
-use core::ffi::c_char;
 use core::panic::PanicInfo;
 
 use flipperzero_sys as sys;
@@ -21,24 +20,21 @@ pub fn panic(panic_info: &PanicInfo<'_>) -> ! {
         sys::__wrap_printf(c"\x1b[0;31mthread: '%s' paniced".as_ptr(), thread_name);
 
         if let Some(s) = panic_info.message().as_str() {
-            sys::__wrap_printf(c" at '%*s'".as_ptr(), s.len(), s.as_ptr() as *const c_char);
+            sys::__wrap_printf(c" at '%.*s'".as_ptr(), s.len(), s.as_ptr());
         }
 
         if let Some(location) = panic_info.location() {
             let file = location.file();
             let line = location.line();
 
-            sys::__wrap_printf(
-                c", %*s:%u".as_ptr(),
-                file.len(),
-                file.as_ptr() as *const c_char,
-                line,
-            );
+            sys::__wrap_printf(c", %.*s:%u".as_ptr(), file.len(), file.as_ptr(), line);
         }
 
         sys::__wrap_printf(c"\x1b[0m\r\n".as_ptr());
         sys::furi_thread_stdout_flush();
-        sys::furi_thread_yield(); // Allow console to flush
+
+        // Ensure there's plenty of time to fully flush the console
+        sys::furi_delay_ms(500);
 
         sys::crash!("Rust panic")
     }