Merge pull request #65 from FenrirWolf/fix-panics

Update to new panic ABI

3 files changed, 126 insertions, 226 deletions

diff --git a/ctr-std/src/lib.rs b/ctr-std/src/lib.rs
index 146e23c..d5d4f49 100644
--- a/ctr-std/src/lib.rs
+++ b/ctr-std/src/lib.rs
@@ -289,6 +289,7 @@
 #![feature(on_unimplemented)]
 #![feature(oom)]
 #![feature(optin_builtin_traits)]
+#![feature(panic_internals)]
 #![feature(panic_unwind)]
 #![feature(peek)]
 #![feature(placement_in_syntax)]
@@ -305,6 +306,7 @@
 #![feature(slice_internals)]
 #![feature(slice_patterns)]
 #![feature(staged_api)]
+#![feature(std_internals)]
 #![feature(stdsimd)]
 #![feature(stmt_expr_attributes)]
 #![feature(str_char)]
diff --git a/ctr-std/src/panicking.rs b/ctr-std/src/panicking.rs
index cbc375f..ad0a337 100644
--- a/ctr-std/src/panicking.rs
+++ b/ctr-std/src/panicking.rs
@@ -17,18 +17,19 @@
 //! * Executing a panic up to doing the actual implementation
 //! * Shims around "try"
 
-#![allow(unused_imports)]
+use core::panic::BoxMeUp;
 
 use io::prelude::*;
 
 use any::Any;
 use cell::RefCell;
+use core::panic::{PanicInfo, Location};
 use fmt;
 use intrinsics;
 use mem;
 use ptr;
 use raw;
-use sys::stdio::Stderr;
+use sys::stdio::{Stderr, stderr_prints_nothing};
 use sys_common::rwlock::RWLock;
 use sys_common::thread_info;
 use sys_common::util;
@@ -57,7 +58,7 @@ extern {
                                 data_ptr: *mut usize,
                                 vtable_ptr: *mut usize) -> u32;
     #[unwind(allowed)]
-    fn __rust_start_panic(data: usize, vtable: usize) -> u32;
+    fn __rust_start_panic(payload: usize) -> u32;
 }
 
 #[derive(Copy, Clone)]
@@ -160,182 +161,6 @@ pub fn take_hook() -> Box<Fn(&PanicInfo) + 'static + Sync + Send> {
     }
 }
 
-/// A struct providing information about a panic.
-///
-/// `PanicInfo` structure is passed to a panic hook set by the [`set_hook`]
-/// function.
-///
-/// [`set_hook`]: ../../std/panic/fn.set_hook.html
-///
-/// # Examples
-///
-/// ```should_panic
-/// use std::panic;
-///
-/// panic::set_hook(Box::new(|panic_info| {
-///     println!("panic occurred: {:?}", panic_info.payload().downcast_ref::<&str>().unwrap());
-/// }));
-///
-/// panic!("Normal panic");
-/// ```
-#[stable(feature = "panic_hooks", since = "1.10.0")]
-#[derive(Debug)]
-pub struct PanicInfo<'a> {
-    payload: &'a (Any + Send),
-    location: Location<'a>,
-}
-
-impl<'a> PanicInfo<'a> {
-    /// Returns the payload associated with the panic.
-    ///
-    /// This will commonly, but not always, be a `&'static str` or [`String`].
-    ///
-    /// [`String`]: ../../std/string/struct.String.html
-    ///
-    /// # Examples
-    ///
-    /// ```should_panic
-    /// use std::panic;
-    ///
-    /// panic::set_hook(Box::new(|panic_info| {
-    ///     println!("panic occurred: {:?}", panic_info.payload().downcast_ref::<&str>().unwrap());
-    /// }));
-    ///
-    /// panic!("Normal panic");
-    /// ```
-    #[stable(feature = "panic_hooks", since = "1.10.0")]
-    pub fn payload(&self) -> &(Any + Send) {
-        self.payload
-    }
-
-    /// Returns information about the location from which the panic originated,
-    /// if available.
-    ///
-    /// This method will currently always return [`Some`], but this may change
-    /// in future versions.
-    ///
-    /// [`Some`]: ../../std/option/enum.Option.html#variant.Some
-    ///
-    /// # Examples
-    ///
-    /// ```should_panic
-    /// use std::panic;
-    ///
-    /// panic::set_hook(Box::new(|panic_info| {
-    ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred in file '{}' at line {}", location.file(),
-    ///             location.line());
-    ///     } else {
-    ///         println!("panic occurred but can't get location information...");
-    ///     }
-    /// }));
-    ///
-    /// panic!("Normal panic");
-    /// ```
-    #[stable(feature = "panic_hooks", since = "1.10.0")]
-    pub fn location(&self) -> Option<&Location> {
-        Some(&self.location)
-    }
-}
-
-/// A struct containing information about the location of a panic.
-///
-/// This structure is created by the [`location`] method of [`PanicInfo`].
-///
-/// [`location`]: ../../std/panic/struct.PanicInfo.html#method.location
-/// [`PanicInfo`]: ../../std/panic/struct.PanicInfo.html
-///
-/// # Examples
-///
-/// ```should_panic
-/// use std::panic;
-///
-/// panic::set_hook(Box::new(|panic_info| {
-///     if let Some(location) = panic_info.location() {
-///         println!("panic occurred in file '{}' at line {}", location.file(), location.line());
-///     } else {
-///         println!("panic occurred but can't get location information...");
-///     }
-/// }));
-///
-/// panic!("Normal panic");
-/// ```
-#[derive(Debug)]
-#[stable(feature = "panic_hooks", since = "1.10.0")]
-pub struct Location<'a> {
-    file: &'a str,
-    line: u32,
-    col: u32,
-}
-
-impl<'a> Location<'a> {
-    /// Returns the name of the source file from which the panic originated.
-    ///
-    /// # Examples
-    ///
-    /// ```should_panic
-    /// use std::panic;
-    ///
-    /// panic::set_hook(Box::new(|panic_info| {
-    ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred in file '{}'", location.file());
-    ///     } else {
-    ///         println!("panic occurred but can't get location information...");
-    ///     }
-    /// }));
-    ///
-    /// panic!("Normal panic");
-    /// ```
-    #[stable(feature = "panic_hooks", since = "1.10.0")]
-    pub fn file(&self) -> &str {
-        self.file
-    }
-
-    /// Returns the line number from which the panic originated.
-    ///
-    /// # Examples
-    ///
-    /// ```should_panic
-    /// use std::panic;
-    ///
-    /// panic::set_hook(Box::new(|panic_info| {
-    ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred at line {}", location.line());
-    ///     } else {
-    ///         println!("panic occurred but can't get location information...");
-    ///     }
-    /// }));
-    ///
-    /// panic!("Normal panic");
-    /// ```
-    #[stable(feature = "panic_hooks", since = "1.10.0")]
-    pub fn line(&self) -> u32 {
-        self.line
-    }
-
-    /// Returns the column from which the panic originated.
-    ///
-    /// # Examples
-    ///
-    /// ```should_panic
-    /// use std::panic;
-    ///
-    /// panic::set_hook(Box::new(|panic_info| {
-    ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred at column {}", location.column());
-    ///     } else {
-    ///         println!("panic occurred but can't get location information...");
-    ///     }
-    /// }));
-    ///
-    /// panic!("Normal panic");
-    /// ```
-    #[stable(feature = "panic_col", since = "1.25")]
-    pub fn column(&self) -> u32 {
-        self.col
-    }
-}
-
 fn default_hook(info: &PanicInfo) {
     #[cfg(feature = "backtrace")]
     use sys_common::backtrace;
@@ -353,18 +178,16 @@ fn default_hook(info: &PanicInfo) {
         }
     };
 
-    let file = info.location.file;
-    let line = info.location.line;
-    let col = info.location.col;
+    let location = info.location().unwrap();  // The current implementation always returns Some
 
-    let msg = match info.payload.downcast_ref::<&'static str>() {
+    let msg = match info.payload().downcast_ref::<&'static str>() {
         Some(s) => *s,
-        None => match info.payload.downcast_ref::<String>() {
+        None => match info.payload().downcast_ref::<String>() {
             Some(s) => &s[..],
             None => "Box<Any>",
         }
     };
-
+    let mut err = Stderr::new().ok();
     let thread = thread_info::current_thread();
     let name = thread.as_ref().and_then(|t| t.name()).unwrap_or("<unnamed>");
 
@@ -372,8 +195,8 @@ fn default_hook(info: &PanicInfo) {
     use libctru::{errorInit, errorText, errorDisp, errorConf, ERROR_TEXT_WORD_WRAP,
                   CFG_LANGUAGE_EN, consoleDebugInit, debugDevice_SVC};
 
-    let error_text = format!("thread '{}' panicked at '{}', {}:{}:{}",
-                             name, msg, file, line, col);
+    let error_text = format!("thread '{}' panicked at '{}', {}", name, msg, location);
+
     unsafe {
         // Prepare error message for display
         let mut error_conf: errorConf = mem::uninitialized();
@@ -393,7 +216,6 @@ fn default_hook(info: &PanicInfo) {
         consoleDebugInit(debugDevice_SVC);
     }
 
-    let mut err = Stderr::new().ok();
     let write = |err: &mut ::io::Write| {
         let _ = write!(err, "{}", error_text);
 
@@ -413,20 +235,19 @@ fn default_hook(info: &PanicInfo) {
 
     let prev = LOCAL_STDERR.with(|s| s.borrow_mut().take());
     match (prev, err.as_mut()) {
-        (Some(mut stderr), _) => {
-            write(&mut *stderr);
-            let mut s = Some(stderr);
-            LOCAL_STDERR.with(|slot| {
-                *slot.borrow_mut() = s.take();
-            });
-        }
-        (None, Some(ref mut err)) => { write(err) }
-        _ => {}
+       (Some(mut stderr), _) => {
+           write(&mut *stderr);
+           let mut s = Some(stderr);
+           LOCAL_STDERR.with(|slot| {
+               *slot.borrow_mut() = s.take();
+           });
+       }
+       (None, Some(ref mut err)) => { write(err) }
+       _ => {}
     }
-    // TODO: If we ever implement backtrace functionality, determine the best way to
-    // incorporate it with the error applet
 }
 
+
 #[cfg(not(test))]
 #[doc(hidden)]
 #[unstable(feature = "update_panic_count", issue = "0")]
@@ -544,9 +365,38 @@ pub fn begin_panic_fmt(msg: &fmt::Arguments,
     // panic + OOM properly anyway (see comment in begin_panic
     // below).
 
-    let mut s = String::new();
-    let _ = s.write_fmt(*msg);
-    begin_panic(s, file_line_col)
+    rust_panic_with_hook(&mut PanicPayload::new(msg), Some(msg), file_line_col);
+
+    struct PanicPayload<'a> {
+        inner: &'a fmt::Arguments<'a>,
+        string: Option<String>,
+    }
+
+    impl<'a> PanicPayload<'a> {
+        fn new(inner: &'a fmt::Arguments<'a>) -> PanicPayload<'a> {
+            PanicPayload { inner, string: None }
+        }
+
+        fn fill(&mut self) -> &mut String {
+            let inner = self.inner;
+            self.string.get_or_insert_with(|| {
+                let mut s = String::new();
+                drop(s.write_fmt(*inner));
+                s
+            })
+        }
+    }
+
+    unsafe impl<'a> BoxMeUp for PanicPayload<'a> {
+        fn box_me_up(&mut self) -> *mut (Any + Send) {
+            let contents = mem::replace(self.fill(), String::new());
+            Box::into_raw(Box::new(contents))
+        }
+
+        fn get(&mut self) -> &(Any + Send) {
+            self.fill()
+        }
+    }
 }
 
 /// This is the entry point of panicking for panic!() and assert!().
@@ -562,18 +412,43 @@ pub fn begin_panic<M: Any + Send>(msg: M, file_line_col: &(&'static str, u32, u3
     // be performed in the parent of this thread instead of the thread that's
     // panicking.
 
-    rust_panic_with_hook(Box::new(msg), file_line_col)
+    rust_panic_with_hook(&mut PanicPayload::new(msg), None, file_line_col);
+
+    struct PanicPayload<A> {
+        inner: Option<A>,
+    }
+
+    impl<A: Send + 'static> PanicPayload<A> {
+        fn new(inner: A) -> PanicPayload<A> {
+            PanicPayload { inner: Some(inner) }
+        }
+    }
+
+    unsafe impl<A: Send + 'static> BoxMeUp for PanicPayload<A> {
+        fn box_me_up(&mut self) -> *mut (Any + Send) {
+            let data = match self.inner.take() {
+                Some(a) => Box::new(a) as Box<Any + Send>,
+                None => Box::new(()),
+            };
+            Box::into_raw(data)
+        }
+
+        fn get(&mut self) -> &(Any + Send) {
+            match self.inner {
+                Some(ref a) => a,
+                None => &(),
+            }
+        }
+    }
 }
 
-/// Executes the primary logic for a panic, including checking for recursive
-/// panics and panic hooks.
+/// Central point for dispatching panics.
 ///
-/// This is the entry point or panics from libcore, formatted panics, and
-/// `Box<Any>` panics. Here we'll verify that we're not panicking recursively,
-/// run panic hooks, and then delegate to the actual implementation of panics.
-#[inline(never)]
-#[cold]
-fn rust_panic_with_hook(msg: Box<Any + Send>,
+/// Executes the primary logic for a panic, including checking for recursive
+/// panics, panic hooks, and finally dispatching to the panic runtime to either
+/// abort or unwind.
+fn rust_panic_with_hook(payload: &mut BoxMeUp,
+                        message: Option<&fmt::Arguments>,
                         file_line_col: &(&'static str, u32, u32)) -> ! {
     let (file, line, col) = *file_line_col;
 
@@ -591,18 +466,24 @@ fn rust_panic_with_hook(msg: Box<Any + Send>,
     }
 
     unsafe {
-        let info = PanicInfo {
-            payload: &*msg,
-            location: Location {
-                file,
-                line,
-                col,
-            },
-        };
+        let mut info = PanicInfo::internal_constructor(
+            message,
+            Location::internal_constructor(file, line, col),
+        );
         HOOK_LOCK.read();
         match HOOK {
-            Hook::Default => default_hook(&info),
-            Hook::Custom(ptr) => (*ptr)(&info),
+            // Some platforms know that printing to stderr won't ever actually
+            // print anything, and if that's the case we can skip the default
+            // hook.
+            Hook::Default if stderr_prints_nothing() => {}
+            Hook::Default => {
+                info.set_payload(payload.get());
+                default_hook(&info);
+            }
+            Hook::Custom(ptr) => {
+                info.set_payload(payload.get());
+                (*ptr)(&info);
+            }
         }
         HOOK_LOCK.read_unlock();
     }
@@ -617,22 +498,35 @@ fn rust_panic_with_hook(msg: Box<Any + Send>,
         unsafe { intrinsics::abort() }
     }
 
-    rust_panic(msg)
+    rust_panic(payload)
 }
 
 /// Shim around rust_panic. Called by resume_unwind.
 pub fn update_count_then_panic(msg: Box<Any + Send>) -> ! {
     update_panic_count(1);
-    rust_panic(msg)
+
+    struct RewrapBox(Box<Any + Send>);
+
+    unsafe impl BoxMeUp for RewrapBox {
+        fn box_me_up(&mut self) -> *mut (Any + Send) {
+            Box::into_raw(mem::replace(&mut self.0, Box::new(())))
+        }
+
+        fn get(&mut self) -> &(Any + Send) {
+            &*self.0
+        }
+    }
+
+    rust_panic(&mut RewrapBox(msg))
 }
 
 /// A private no-mangle function on which to slap yer breakpoints.
 #[no_mangle]
 #[allow(private_no_mangle_fns)] // yes we get it, but we like breakpoints
-pub fn rust_panic(msg: Box<Any + Send>) -> ! {
+pub fn rust_panic(mut msg: &mut BoxMeUp) -> ! {
     let code = unsafe {
-        let obj = mem::transmute::<_, raw::TraitObject>(msg);
-        __rust_start_panic(obj.data as usize, obj.vtable as usize)
+        let obj = &mut msg as *mut &mut BoxMeUp;
+        __rust_start_panic(obj as usize)
     };
     rtabort!("failed to initiate panic, error {}", code)
 }
diff --git a/ctr-std/src/sys/unix/stdio.rs b/ctr-std/src/sys/unix/stdio.rs
index e9b3d4a..87ba2ae 100644
--- a/ctr-std/src/sys/unix/stdio.rs
+++ b/ctr-std/src/sys/unix/stdio.rs
@@ -75,3 +75,7 @@ pub fn is_ebadf(err: &io::Error) -> bool {
 }
 
 pub const STDIN_BUF_SIZE: usize = ::sys_common::io::DEFAULT_BUF_SIZE;
+
+pub fn stderr_prints_nothing() -> bool {
+    false
+}