Save crash logs to disk

src/main.rs

@@ -1,7 +1,7 @@
 // hide console in release mode
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
-use std::{path::PathBuf, process};
+use std::{path::PathBuf, process, time::SystemTime};
 
 use anyhow::Result;
 use app::Application;
@@ -24,6 +24,43 @@ struct Args {
     rom: Option<PathBuf>,
 }
 
+fn set_panic_handler() {
+    std::panic::set_hook(Box::new(|info| {
+        let mut message = String::new();
+        if let Some(msg) = info.payload().downcast_ref::<&str>() {
+            message += &format!("{}\n", msg);
+        } else if let Some(msg) = info.payload().downcast_ref::<String>() {
+            message += &format!("{}\n", msg);
+        }
+        if let Some(location) = info.location() {
+            message += &format!(
+                "    in file '{}' at line {}\n",
+                location.file(),
+                location.line()
+            );
+        }
+        let backtrace = std::backtrace::Backtrace::force_capture();
+        message += &format!("stack trace:\n{:#}\n", backtrace);
+
+        eprint!("{}", message);
+
+        let Some(project_dirs) = directories::ProjectDirs::from("com", "virtual-boy", "Lemur")
+        else {
+            return;
+        };
+        let data_dir = project_dirs.data_dir();
+        if std::fs::create_dir_all(data_dir).is_err() {
+            return;
+        }
+        let timestamp = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap()
+            .as_millis();
+        let logfile_name = format!("crash-{}.txt", timestamp);
+        let _ = std::fs::write(data_dir.join(logfile_name), message);
+    }));
+}
+
 #[cfg(windows)]
 fn set_process_priority_to_high() -> Result<()> {
     use windows::Win32::{Foundation, System::Threading};
@@ -34,6 +71,8 @@ fn set_process_priority_to_high() -> Result<()> {
 }
 
 fn main() -> Result<()> {
+    set_panic_handler();
+
     #[cfg(windows)]
     set_process_priority_to_high()?;