diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/num/f32.rs | 27 | ||||
| -rw-r--r-- | src/libstd/num/f64.rs | 9 | ||||
| -rw-r--r-- | src/libstd/rand/os.rs | 1 | ||||
| -rw-r--r-- | src/libstd/rt/unwind.rs | 615 | ||||
| -rw-r--r-- | src/libstd/rt/unwind/gcc.rs | 342 | ||||
| -rw-r--r-- | src/libstd/rt/unwind/mod.rs | 319 | ||||
| -rw-r--r-- | src/libstd/rt/unwind/seh.rs | 30 |
7 files changed, 715 insertions, 628 deletions
diff --git a/src/libstd/num/f32.rs b/src/libstd/num/f32.rs index 1ee3aab2727..e31d97b3240 100644 --- a/src/libstd/num/f32.rs +++ b/src/libstd/num/f32.rs @@ -32,7 +32,6 @@ pub use core::f32::consts; mod cmath { use libc::{c_float, c_int}; - #[link_name = "m"] extern { pub fn acosf(n: c_float) -> c_float; pub fn asinf(n: c_float) -> c_float; @@ -44,13 +43,10 @@ mod cmath { pub fn erfcf(n: c_float) -> c_float; pub fn expm1f(n: c_float) -> c_float; pub fn fdimf(a: c_float, b: c_float) -> c_float; - pub fn frexpf(n: c_float, value: &mut c_int) -> c_float; pub fn fmaxf(a: c_float, b: c_float) -> c_float; pub fn fminf(a: c_float, b: c_float) -> c_float; pub fn fmodf(a: c_float, b: c_float) -> c_float; pub fn nextafterf(x: c_float, y: c_float) -> c_float; - pub fn hypotf(x: c_float, y: c_float) -> c_float; - pub fn ldexpf(x: c_float, n: c_int) -> c_float; pub fn logbf(n: c_float) -> c_float; pub fn log1pf(n: c_float) -> c_float; pub fn ilogbf(n: c_float) -> c_int; @@ -60,12 +56,27 @@ mod cmath { pub fn tanhf(n: c_float) -> c_float; pub fn tgammaf(n: c_float) -> c_float; - #[cfg(unix)] + #[cfg_attr(all(windows, target_env = "msvc"), link_name = "__lgammaf_r")] pub fn lgammaf_r(n: c_float, sign: &mut c_int) -> c_float; + #[cfg_attr(all(windows, target_env = "msvc"), link_name = "_hypotf")] + pub fn hypotf(x: c_float, y: c_float) -> c_float; - #[cfg(windows)] - #[link_name="__lgammaf_r"] - pub fn lgammaf_r(n: c_float, sign: &mut c_int) -> c_float; + #[cfg(any(unix, all(windows, not(target_env = "msvc"))))] + pub fn frexpf(n: c_float, value: &mut c_int) -> c_float; + #[cfg(any(unix, all(windows, not(target_env = "msvc"))))] + pub fn ldexpf(x: c_float, n: c_int) -> c_float; + } + + #[cfg(all(windows, target_env = "msvc"))] + pub unsafe fn ldexpf(x: c_float, n: c_int) -> c_float { + f64::ldexp(x as f64, n as isize) as c_float + } + + #[cfg(all(windows, target_env = "msvc"))] + pub unsafe fn frexpf(x: c_float, value: &mut c_int) -> c_float { + let (a, b) = f64::frexp(x as f64); + *value = b as c_int; + a as c_float } } diff --git a/src/libstd/num/f64.rs b/src/libstd/num/f64.rs index 398afcb553c..e87855ffd4e 100644 --- a/src/libstd/num/f64.rs +++ b/src/libstd/num/f64.rs @@ -48,7 +48,6 @@ mod cmath { pub fn fmod(a: c_double, b: c_double) -> c_double; pub fn nextafter(x: c_double, y: c_double) -> c_double; pub fn frexp(n: c_double, value: &mut c_int) -> c_double; - pub fn hypot(x: c_double, y: c_double) -> c_double; pub fn ldexp(x: c_double, n: c_int) -> c_double; pub fn logb(n: c_double) -> c_double; pub fn log1p(n: c_double) -> c_double; @@ -69,11 +68,11 @@ mod cmath { pub fn y1(n: c_double) -> c_double; pub fn yn(i: c_int, n: c_double) -> c_double; - #[cfg(unix)] - pub fn lgamma_r(n: c_double, sign: &mut c_int) -> c_double; - #[cfg(windows)] - #[link_name="__lgamma_r"] + #[cfg_attr(all(windows, target_env = "msvc"), link_name = "__lgamma_r")] pub fn lgamma_r(n: c_double, sign: &mut c_int) -> c_double; + + #[cfg_attr(all(windows, target_env = "msvc"), link_name = "_hypot")] + pub fn hypot(x: c_double, y: c_double) -> c_double; } } diff --git a/src/libstd/rand/os.rs b/src/libstd/rand/os.rs index 3c36f0f1d49..885adf19ca1 100644 --- a/src/libstd/rand/os.rs +++ b/src/libstd/rand/os.rs @@ -279,6 +279,7 @@ mod imp { const CRYPT_VERIFYCONTEXT: DWORD = 0xF0000000; #[allow(non_snake_case)] + #[link(name = "advapi32")] extern "system" { fn CryptAcquireContextA(phProv: *mut HCRYPTPROV, pszContainer: LPCSTR, diff --git a/src/libstd/rt/unwind.rs b/src/libstd/rt/unwind.rs deleted file mode 100644 index b24099505ed..00000000000 --- a/src/libstd/rt/unwind.rs +++ /dev/null @@ -1,615 +0,0 @@ -// Copyright 2013 The Rust Project Developers. See the COPYRIGHT -// file at the top-level directory of this distribution and at -// http://rust-lang.org/COPYRIGHT. -// -// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or -// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license -// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. - -//! Implementation of Rust stack unwinding -//! -//! For background on exception handling and stack unwinding please see -//! "Exception Handling in LLVM" (llvm.org/docs/ExceptionHandling.html) and -//! documents linked from it. -//! These are also good reads: -//! http://theofilos.cs.columbia.edu/blog/2013/09/22/base_abi/ -//! http://monoinfinito.wordpress.com/series/exception-handling-in-c/ -//! http://www.airs.com/blog/index.php?s=exception+frames -//! -//! ## A brief summary -//! -//! Exception handling happens in two phases: a search phase and a cleanup phase. -//! -//! In both phases the unwinder walks stack frames from top to bottom using -//! information from the stack frame unwind sections of the current process's -//! modules ("module" here refers to an OS module, i.e. an executable or a -//! dynamic library). -//! -//! For each stack frame, it invokes the associated "personality routine", whose -//! address is also stored in the unwind info section. -//! -//! In the search phase, the job of a personality routine is to examine exception -//! object being thrown, and to decide whether it should be caught at that stack -//! frame. Once the handler frame has been identified, cleanup phase begins. -//! -//! In the cleanup phase, personality routines invoke cleanup code associated -//! with their stack frames (i.e. destructors). Once stack has been unwound down -//! to the handler frame level, unwinding stops and the last personality routine -//! transfers control to its catch block. -//! -//! ## Frame unwind info registration -//! -//! Each module has its own frame unwind info section (usually ".eh_frame"), and -//! unwinder needs to know about all of them in order for unwinding to be able to -//! cross module boundaries. -//! -//! On some platforms, like Linux, this is achieved by dynamically enumerating -//! currently loaded modules via the dl_iterate_phdr() API and finding all -//! .eh_frame sections. -//! -//! Others, like Windows, require modules to actively register their unwind info -//! sections by calling __register_frame_info() API at startup. In the latter -//! case it is essential that there is only one copy of the unwinder runtime in -//! the process. This is usually achieved by linking to the dynamic version of -//! the unwind runtime. -//! -//! Currently Rust uses unwind runtime provided by libgcc. - -use prelude::v1::*; - -use any::Any; -use boxed; -use cell::Cell; -use cmp; -use panicking; -use fmt; -use intrinsics; -use libc::c_void; -use mem; -use sync::atomic::{self, Ordering}; -use sys_common::mutex::{Mutex, MUTEX_INIT}; - -use rt::libunwind as uw; - -struct Exception { - uwe: uw::_Unwind_Exception, - cause: Option<Box<Any + Send + 'static>>, -} - -pub type Callback = fn(msg: &(Any + Send), file: &'static str, line: u32); - -// Variables used for invoking callbacks when a thread starts to unwind. -// -// For more information, see below. -const MAX_CALLBACKS: usize = 16; -static CALLBACKS: [atomic::AtomicUsize; MAX_CALLBACKS] = - [atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, - atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT]; -static CALLBACK_CNT: atomic::AtomicUsize = atomic::ATOMIC_USIZE_INIT; - -thread_local! { static PANICKING: Cell<bool> = Cell::new(false) } - -/// Invoke a closure, capturing the cause of panic if one occurs. -/// -/// This function will return `Ok(())` if the closure did not panic, and will -/// return `Err(cause)` if the closure panics. The `cause` returned is the -/// object with which panic was originally invoked. -/// -/// This function also is unsafe for a variety of reasons: -/// -/// * This is not safe to call in a nested fashion. The unwinding -/// interface for Rust is designed to have at most one try/catch block per -/// thread, not multiple. No runtime checking is currently performed to uphold -/// this invariant, so this function is not safe. A nested try/catch block -/// may result in corruption of the outer try/catch block's state, especially -/// if this is used within a thread itself. -/// -/// * It is not sound to trigger unwinding while already unwinding. Rust threads -/// have runtime checks in place to ensure this invariant, but it is not -/// guaranteed that a rust thread is in place when invoking this function. -/// Unwinding twice can lead to resource leaks where some destructors are not -/// run. -pub unsafe fn try<F: FnOnce()>(f: F) -> Result<(), Box<Any + Send>> { - let mut f = Some(f); - - let prev = PANICKING.with(|s| s.get()); - PANICKING.with(|s| s.set(false)); - let ep = rust_try(try_fn::<F>, &mut f as *mut _ as *mut c_void); - PANICKING.with(|s| s.set(prev)); - return if ep.is_null() { - Ok(()) - } else { - let my_ep = ep as *mut Exception; - rtdebug!("caught {}", (*my_ep).uwe.exception_class); - let cause = (*my_ep).cause.take(); - uw::_Unwind_DeleteException(ep); - Err(cause.unwrap()) - }; - - extern fn try_fn<F: FnOnce()>(opt_closure: *mut c_void) { - let opt_closure = opt_closure as *mut Option<F>; - unsafe { (*opt_closure).take().unwrap()(); } - } - - #[link(name = "rustrt_native", kind = "static")] - #[cfg(not(test))] - extern {} - - extern { - // Rust's try-catch - // When f(...) returns normally, the return value is null. - // When f(...) throws, the return value is a pointer to the caught - // exception object. - fn rust_try(f: extern fn(*mut c_void), - data: *mut c_void) -> *mut uw::_Unwind_Exception; - } -} - -/// Determines whether the current thread is unwinding because of panic. -pub fn panicking() -> bool { - PANICKING.with(|s| s.get()) -} - -// An uninlined, unmangled function upon which to slap yer breakpoints -#[inline(never)] -#[no_mangle] -#[allow(private_no_mangle_fns)] -fn rust_panic(cause: Box<Any + Send + 'static>) -> ! { - rtdebug!("begin_unwind()"); - - unsafe { - let exception: Box<_> = box Exception { - uwe: uw::_Unwind_Exception { - exception_class: rust_exception_class(), - exception_cleanup: exception_cleanup, - private: [0; uw::unwinder_private_data_size], - }, - cause: Some(cause), - }; - let exception_param = boxed::into_raw(exception) as *mut uw::_Unwind_Exception; - let error = uw::_Unwind_RaiseException(exception_param); - rtabort!("Could not unwind stack, error = {}", error as isize) - } - - extern fn exception_cleanup(_unwind_code: uw::_Unwind_Reason_Code, - exception: *mut uw::_Unwind_Exception) { - rtdebug!("exception_cleanup()"); - unsafe { - let _: Box<Exception> = Box::from_raw(exception as *mut Exception); - } - } -} - -// Rust's exception class identifier. This is used by personality routines to -// determine whether the exception was thrown by their own runtime. -fn rust_exception_class() -> uw::_Unwind_Exception_Class { - // M O Z \0 R U S T -- vendor, language - 0x4d4f5a_00_52555354 -} - -// We could implement our personality routine in pure Rust, however exception -// info decoding is tedious. More importantly, personality routines have to -// handle various platform quirks, which are not fun to maintain. For this -// reason, we attempt to reuse personality routine of the C language: -// __gcc_personality_v0. -// -// Since C does not support exception catching, __gcc_personality_v0 simply -// always returns _URC_CONTINUE_UNWIND in search phase, and always returns -// _URC_INSTALL_CONTEXT (i.e. "invoke cleanup code") in cleanup phase. -// -// This is pretty close to Rust's exception handling approach, except that Rust -// does have a single "catch-all" handler at the bottom of each thread's stack. -// So we have two versions of the personality routine: -// - rust_eh_personality, used by all cleanup landing pads, which never catches, -// so the behavior of __gcc_personality_v0 is perfectly adequate there, and -// - rust_eh_personality_catch, used only by rust_try(), which always catches. -// -// Note, however, that for implementation simplicity, rust_eh_personality_catch -// lacks code to install a landing pad, so in order to obtain exception object -// pointer (which it needs to return upstream), rust_try() employs another trick: -// it calls into the nested rust_try_inner(), whose landing pad does not resume -// unwinds. Instead, it extracts the exception pointer and performs a "normal" -// return. -// -// See also: rt/rust_try.ll - -#[cfg(all(not(target_arch = "arm"), - not(all(windows, target_arch = "x86_64")), - not(test)))] -#[doc(hidden)] -pub mod eabi { - use rt::libunwind as uw; - use libc::c_int; - - extern "C" { - fn __gcc_personality_v0(version: c_int, - actions: uw::_Unwind_Action, - exception_class: uw::_Unwind_Exception_Class, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code; - } - - #[lang = "eh_personality"] - #[no_mangle] // referenced from rust_try.ll - #[allow(private_no_mangle_fns)] - extern fn rust_eh_personality( - version: c_int, - actions: uw::_Unwind_Action, - exception_class: uw::_Unwind_Exception_Class, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - unsafe { - __gcc_personality_v0(version, actions, exception_class, ue_header, - context) - } - } - - #[no_mangle] // referenced from rust_try.ll - pub extern "C" fn rust_eh_personality_catch( - _version: c_int, - actions: uw::_Unwind_Action, - _exception_class: uw::_Unwind_Exception_Class, - _ue_header: *mut uw::_Unwind_Exception, - _context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - - if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase - uw::_URC_HANDLER_FOUND // catch! - } - else { // cleanup phase - uw::_URC_INSTALL_CONTEXT - } - } -} - -// iOS on armv7 is using SjLj exceptions and therefore requires to use -// a specialized personality routine: __gcc_personality_sj0 - -#[cfg(all(target_os = "ios", target_arch = "arm", not(test)))] -#[doc(hidden)] -pub mod eabi { - use rt::libunwind as uw; - use libc::c_int; - - extern "C" { - fn __gcc_personality_sj0(version: c_int, - actions: uw::_Unwind_Action, - exception_class: uw::_Unwind_Exception_Class, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code; - } - - #[lang = "eh_personality"] - #[no_mangle] // referenced from rust_try.ll - pub extern "C" fn rust_eh_personality( - version: c_int, - actions: uw::_Unwind_Action, - exception_class: uw::_Unwind_Exception_Class, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - unsafe { - __gcc_personality_sj0(version, actions, exception_class, ue_header, - context) - } - } - - #[no_mangle] // referenced from rust_try.ll - pub extern "C" fn rust_eh_personality_catch( - _version: c_int, - actions: uw::_Unwind_Action, - _exception_class: uw::_Unwind_Exception_Class, - _ue_header: *mut uw::_Unwind_Exception, - _context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase - uw::_URC_HANDLER_FOUND // catch! - } - else { // cleanup phase - unsafe { - __gcc_personality_sj0(_version, actions, _exception_class, _ue_header, - _context) - } - } - } -} - - -// ARM EHABI uses a slightly different personality routine signature, -// but otherwise works the same. -#[cfg(all(target_arch = "arm", not(target_os = "ios"), not(test)))] -#[doc(hidden)] -pub mod eabi { - use rt::libunwind as uw; - use libc::c_int; - - extern "C" { - fn __gcc_personality_v0(state: uw::_Unwind_State, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code; - } - - #[lang = "eh_personality"] - #[no_mangle] // referenced from rust_try.ll - #[allow(private_no_mangle_fns)] - extern "C" fn rust_eh_personality( - state: uw::_Unwind_State, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - unsafe { - __gcc_personality_v0(state, ue_header, context) - } - } - - #[no_mangle] // referenced from rust_try.ll - pub extern "C" fn rust_eh_personality_catch( - state: uw::_Unwind_State, - _ue_header: *mut uw::_Unwind_Exception, - _context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - if (state as c_int & uw::_US_ACTION_MASK as c_int) - == uw::_US_VIRTUAL_UNWIND_FRAME as c_int { // search phase - uw::_URC_HANDLER_FOUND // catch! - } - else { // cleanup phase - uw::_URC_INSTALL_CONTEXT - } - } -} - -// Win64 SEH (see http://msdn.microsoft.com/en-us/library/1eyas8tf.aspx) -// -// This looks a bit convoluted because rather than implementing a native SEH handler, -// GCC reuses the same personality routine as for the other architectures by wrapping it -// with an "API translator" layer (_GCC_specific_handler). - -#[cfg(all(windows, target_arch = "x86_64", not(test)))] -#[doc(hidden)] -#[allow(non_camel_case_types, non_snake_case)] -pub mod eabi { - pub use self::EXCEPTION_DISPOSITION::*; - use rt::libunwind as uw; - use libc::{c_void, c_int}; - - #[repr(C)] - pub struct EXCEPTION_RECORD; - #[repr(C)] - pub struct CONTEXT; - #[repr(C)] - pub struct DISPATCHER_CONTEXT; - - #[repr(C)] - #[derive(Copy, Clone)] - pub enum EXCEPTION_DISPOSITION { - ExceptionContinueExecution, - ExceptionContinueSearch, - ExceptionNestedException, - ExceptionCollidedUnwind - } - - type _Unwind_Personality_Fn = - extern "C" fn( - version: c_int, - actions: uw::_Unwind_Action, - exception_class: uw::_Unwind_Exception_Class, - ue_header: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code; - - extern "C" { - fn __gcc_personality_seh0( - exceptionRecord: *mut EXCEPTION_RECORD, - establisherFrame: *mut c_void, - contextRecord: *mut CONTEXT, - dispatcherContext: *mut DISPATCHER_CONTEXT - ) -> EXCEPTION_DISPOSITION; - - fn _GCC_specific_handler( - exceptionRecord: *mut EXCEPTION_RECORD, - establisherFrame: *mut c_void, - contextRecord: *mut CONTEXT, - dispatcherContext: *mut DISPATCHER_CONTEXT, - personality: _Unwind_Personality_Fn - ) -> EXCEPTION_DISPOSITION; - } - - #[lang = "eh_personality"] - #[no_mangle] // referenced from rust_try.ll - #[allow(private_no_mangle_fns)] - extern "C" fn rust_eh_personality( - exceptionRecord: *mut EXCEPTION_RECORD, - establisherFrame: *mut c_void, - contextRecord: *mut CONTEXT, - dispatcherContext: *mut DISPATCHER_CONTEXT - ) -> EXCEPTION_DISPOSITION - { - unsafe { - __gcc_personality_seh0(exceptionRecord, establisherFrame, - contextRecord, dispatcherContext) - } - } - - #[no_mangle] // referenced from rust_try.ll - pub extern "C" fn rust_eh_personality_catch( - exceptionRecord: *mut EXCEPTION_RECORD, - establisherFrame: *mut c_void, - contextRecord: *mut CONTEXT, - dispatcherContext: *mut DISPATCHER_CONTEXT - ) -> EXCEPTION_DISPOSITION - { - extern "C" fn inner( - _version: c_int, - actions: uw::_Unwind_Action, - _exception_class: uw::_Unwind_Exception_Class, - _ue_header: *mut uw::_Unwind_Exception, - _context: *mut uw::_Unwind_Context - ) -> uw::_Unwind_Reason_Code - { - if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase - uw::_URC_HANDLER_FOUND // catch! - } - else { // cleanup phase - uw::_URC_INSTALL_CONTEXT - } - } - - unsafe { - _GCC_specific_handler(exceptionRecord, establisherFrame, - contextRecord, dispatcherContext, - inner) - } - } -} - -#[cfg(not(test))] -/// Entry point of panic from the libcore crate. -#[lang = "panic_fmt"] -pub extern fn rust_begin_unwind(msg: fmt::Arguments, - file: &'static str, line: u32) -> ! { - begin_unwind_fmt(msg, &(file, line)) -} - -/// The entry point for unwinding with a formatted message. -/// -/// This is designed to reduce the amount of code required at the call -/// site as much as possible (so that `panic!()` has as low an impact -/// on (e.g.) the inlining of other functions as possible), by moving -/// the actual formatting into this shared place. -#[inline(never)] #[cold] -pub fn begin_unwind_fmt(msg: fmt::Arguments, file_line: &(&'static str, u32)) -> ! { - use fmt::Write; - - // We do two allocations here, unfortunately. But (a) they're - // required with the current scheme, and (b) we don't handle - // panic + OOM properly anyway (see comment in begin_unwind - // below). - - let mut s = String::new(); - let _ = s.write_fmt(msg); - begin_unwind_inner(Box::new(s), file_line) -} - -/// This is the entry point of unwinding for panic!() and assert!(). -#[inline(never)] #[cold] // avoid code bloat at the call sites as much as possible -pub fn begin_unwind<M: Any + Send>(msg: M, file_line: &(&'static str, u32)) -> ! { - // Note that this should be the only allocation performed in this code path. - // Currently this means that panic!() on OOM will invoke this code path, - // but then again we're not really ready for panic on OOM anyway. If - // we do start doing this, then we should propagate this allocation to - // be performed in the parent of this thread instead of the thread that's - // panicking. - - // see below for why we do the `Any` coercion here. - begin_unwind_inner(Box::new(msg), file_line) -} - -/// The core of the unwinding. -/// -/// This is non-generic to avoid instantiation bloat in other crates -/// (which makes compilation of small crates noticeably slower). (Note: -/// we need the `Any` object anyway, we're not just creating it to -/// avoid being generic.) -/// -/// Doing this split took the LLVM IR line counts of `fn main() { panic!() -/// }` from ~1900/3700 (-O/no opts) to 180/590. -#[inline(never)] #[cold] // this is the slow path, please never inline this -fn begin_unwind_inner(msg: Box<Any + Send>, - file_line: &(&'static str, u32)) -> ! { - // Make sure the default failure handler is registered before we look at the - // callbacks. We also use a raw sys-based mutex here instead of a - // `std::sync` one as accessing TLS can cause weird recursive problems (and - // we don't need poison checking). - unsafe { - static LOCK: Mutex = MUTEX_INIT; - static mut INIT: bool = false; - LOCK.lock(); - if !INIT { - register(panicking::on_panic); - INIT = true; - } - LOCK.unlock(); - } - - // First, invoke call the user-defined callbacks triggered on thread panic. - // - // By the time that we see a callback has been registered (by reading - // MAX_CALLBACKS), the actual callback itself may have not been stored yet, - // so we just chalk it up to a race condition and move on to the next - // callback. Additionally, CALLBACK_CNT may briefly be higher than - // MAX_CALLBACKS, so we're sure to clamp it as necessary. - let callbacks = { - let amt = CALLBACK_CNT.load(Ordering::SeqCst); - &CALLBACKS[..cmp::min(amt, MAX_CALLBACKS)] - }; - for cb in callbacks { - match cb.load(Ordering::SeqCst) { - 0 => {} - n => { - let f: Callback = unsafe { mem::transmute(n) }; - let (file, line) = *file_line; - f(&*msg, file, line); - } - } - }; - - // Now that we've run all the necessary unwind callbacks, we actually - // perform the unwinding. - if panicking() { - // If a thread panics while it's already unwinding then we - // have limited options. Currently our preference is to - // just abort. In the future we may consider resuming - // unwinding or otherwise exiting the thread cleanly. - rterrln!("thread panicked while panicking. aborting."); - unsafe { intrinsics::abort() } - } - PANICKING.with(|s| s.set(true)); - rust_panic(msg); -} - -/// Register a callback to be invoked when a thread unwinds. -/// -/// This is an unsafe and experimental API which allows for an arbitrary -/// callback to be invoked when a thread panics. This callback is invoked on both -/// the initial unwinding and a double unwinding if one occurs. Additionally, -/// the local `Thread` will be in place for the duration of the callback, and -/// the callback must ensure that it remains in place once the callback returns. -/// -/// Only a limited number of callbacks can be registered, and this function -/// returns whether the callback was successfully registered or not. It is not -/// currently possible to unregister a callback once it has been registered. -pub unsafe fn register(f: Callback) -> bool { - match CALLBACK_CNT.fetch_add(1, Ordering::SeqCst) { - // The invocation code has knowledge of this window where the count has - // been incremented, but the callback has not been stored. We're - // guaranteed that the slot we're storing into is 0. - n if n < MAX_CALLBACKS => { - let prev = CALLBACKS[n].swap(mem::transmute(f), Ordering::SeqCst); - rtassert!(prev == 0); - true - } - // If we accidentally bumped the count too high, pull it back. - _ => { - CALLBACK_CNT.store(MAX_CALLBACKS, Ordering::SeqCst); - false - } - } -} diff --git a/src/libstd/rt/unwind/gcc.rs b/src/libstd/rt/unwind/gcc.rs new file mode 100644 index 00000000000..39b32a3f08e --- /dev/null +++ b/src/libstd/rt/unwind/gcc.rs @@ -0,0 +1,342 @@ +// Copyright 2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use prelude::v1::*; + +use any::Any; +use boxed; +use libc::c_void; +use rt::libunwind as uw; + +struct Exception { + uwe: uw::_Unwind_Exception, + cause: Option<Box<Any + Send + 'static>>, +} + +pub unsafe fn panic(data: Box<Any + Send + 'static>) -> ! { + let exception: Box<_> = box Exception { + uwe: uw::_Unwind_Exception { + exception_class: rust_exception_class(), + exception_cleanup: exception_cleanup, + private: [0; uw::unwinder_private_data_size], + }, + cause: Some(data), + }; + let exception_param = boxed::into_raw(exception) as *mut uw::_Unwind_Exception; + let error = uw::_Unwind_RaiseException(exception_param); + rtabort!("Could not unwind stack, error = {}", error as isize); + + extern fn exception_cleanup(_unwind_code: uw::_Unwind_Reason_Code, + exception: *mut uw::_Unwind_Exception) { + rtdebug!("exception_cleanup()"); + unsafe { + let _: Box<Exception> = Box::from_raw(exception as *mut Exception); + } + } +} + +pub unsafe fn cleanup(ptr: *mut c_void) -> Box<Any + Send + 'static> { + let my_ep = ptr as *mut Exception; + rtdebug!("caught {}", (*my_ep).uwe.exception_class); + let cause = (*my_ep).cause.take(); + uw::_Unwind_DeleteException(ptr as *mut _); + cause.unwrap() +} + +// Rust's exception class identifier. This is used by personality routines to +// determine whether the exception was thrown by their own runtime. +fn rust_exception_class() -> uw::_Unwind_Exception_Class { + // M O Z \0 R U S T -- vendor, language + 0x4d4f5a_00_52555354 +} + +// We could implement our personality routine in pure Rust, however exception +// info decoding is tedious. More importantly, personality routines have to +// handle various platform quirks, which are not fun to maintain. For this +// reason, we attempt to reuse personality routine of the C language: +// __gcc_personality_v0. +// +// Since C does not support exception catching, __gcc_personality_v0 simply +// always returns _URC_CONTINUE_UNWIND in search phase, and always returns +// _URC_INSTALL_CONTEXT (i.e. "invoke cleanup code") in cleanup phase. +// +// This is pretty close to Rust's exception handling approach, except that Rust +// does have a single "catch-all" handler at the bottom of each thread's stack. +// So we have two versions of the personality routine: +// - rust_eh_personality, used by all cleanup landing pads, which never catches, +// so the behavior of __gcc_personality_v0 is perfectly adequate there, and +// - rust_eh_personality_catch, used only by rust_try(), which always catches. +// +// Note, however, that for implementation simplicity, rust_eh_personality_catch +// lacks code to install a landing pad, so in order to obtain exception object +// pointer (which it needs to return upstream), rust_try() employs another trick: +// it calls into the nested rust_try_inner(), whose landing pad does not resume +// unwinds. Instead, it extracts the exception pointer and performs a "normal" +// return. +// +// See also: rt/rust_try.ll + +#[cfg(all(not(target_arch = "arm"), + not(all(windows, target_arch = "x86_64")), + not(test)))] +pub mod eabi { + use rt::libunwind as uw; + use libc::c_int; + + extern "C" { + fn __gcc_personality_v0(version: c_int, + actions: uw::_Unwind_Action, + exception_class: uw::_Unwind_Exception_Class, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context) + -> uw::_Unwind_Reason_Code; + } + + #[lang="eh_personality"] + #[no_mangle] // referenced from rust_try.ll + #[allow(private_no_mangle_fns)] + extern fn rust_eh_personality( + version: c_int, + actions: uw::_Unwind_Action, + exception_class: uw::_Unwind_Exception_Class, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + unsafe { + __gcc_personality_v0(version, actions, exception_class, ue_header, + context) + } + } + + #[no_mangle] // referenced from rust_try.ll + pub extern "C" fn rust_eh_personality_catch( + _version: c_int, + actions: uw::_Unwind_Action, + _exception_class: uw::_Unwind_Exception_Class, + _ue_header: *mut uw::_Unwind_Exception, + _context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + + if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase + uw::_URC_HANDLER_FOUND // catch! + } + else { // cleanup phase + uw::_URC_INSTALL_CONTEXT + } + } +} + +// iOS on armv7 is using SjLj exceptions and therefore requires to use +// a specialized personality routine: __gcc_personality_sj0 + +#[cfg(all(target_os = "ios", target_arch = "arm", not(test)))] +pub mod eabi { + use rt::libunwind as uw; + use libc::c_int; + + extern "C" { + fn __gcc_personality_sj0(version: c_int, + actions: uw::_Unwind_Action, + exception_class: uw::_Unwind_Exception_Class, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context) + -> uw::_Unwind_Reason_Code; + } + + #[lang="eh_personality"] + #[no_mangle] // referenced from rust_try.ll + pub extern "C" fn rust_eh_personality( + version: c_int, + actions: uw::_Unwind_Action, + exception_class: uw::_Unwind_Exception_Class, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + unsafe { + __gcc_personality_sj0(version, actions, exception_class, ue_header, + context) + } + } + + #[no_mangle] // referenced from rust_try.ll + pub extern "C" fn rust_eh_personality_catch( + _version: c_int, + actions: uw::_Unwind_Action, + _exception_class: uw::_Unwind_Exception_Class, + _ue_header: *mut uw::_Unwind_Exception, + _context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase + uw::_URC_HANDLER_FOUND // catch! + } + else { // cleanup phase + unsafe { + __gcc_personality_sj0(_version, actions, _exception_class, _ue_header, + _context) + } + } + } +} + + +// ARM EHABI uses a slightly different personality routine signature, +// but otherwise works the same. +#[cfg(all(target_arch = "arm", not(target_os = "ios"), not(test)))] +pub mod eabi { + use rt::libunwind as uw; + use libc::c_int; + + extern "C" { + fn __gcc_personality_v0(state: uw::_Unwind_State, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context) + -> uw::_Unwind_Reason_Code; + } + + #[lang="eh_personality"] + #[no_mangle] // referenced from rust_try.ll + #[allow(private_no_mangle_fns)] + extern "C" fn rust_eh_personality( + state: uw::_Unwind_State, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + unsafe { + __gcc_personality_v0(state, ue_header, context) + } + } + + #[no_mangle] // referenced from rust_try.ll + pub extern "C" fn rust_eh_personality_catch( + state: uw::_Unwind_State, + _ue_header: *mut uw::_Unwind_Exception, + _context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + if (state as c_int & uw::_US_ACTION_MASK as c_int) + == uw::_US_VIRTUAL_UNWIND_FRAME as c_int { // search phase + uw::_URC_HANDLER_FOUND // catch! + } + else { // cleanup phase + uw::_URC_INSTALL_CONTEXT + } + } +} + +// Win64 SEH (see http://msdn.microsoft.com/en-us/library/1eyas8tf.aspx) +// +// This looks a bit convoluted because rather than implementing a native SEH +// handler, GCC reuses the same personality routine as for the other +// architectures by wrapping it with an "API translator" layer +// (_GCC_specific_handler). + +#[cfg(all(windows, target_arch = "x86_64", not(test)))] +#[doc(hidden)] +#[allow(non_camel_case_types, non_snake_case)] +pub mod eabi { + pub use self::EXCEPTION_DISPOSITION::*; + use rt::libunwind as uw; + use libc::{c_void, c_int}; + + #[repr(C)] + pub struct EXCEPTION_RECORD; + #[repr(C)] + pub struct CONTEXT; + #[repr(C)] + pub struct DISPATCHER_CONTEXT; + + #[repr(C)] + #[derive(Copy, Clone)] + pub enum EXCEPTION_DISPOSITION { + ExceptionContinueExecution, + ExceptionContinueSearch, + ExceptionNestedException, + ExceptionCollidedUnwind + } + + type _Unwind_Personality_Fn = + extern "C" fn( + version: c_int, + actions: uw::_Unwind_Action, + exception_class: uw::_Unwind_Exception_Class, + ue_header: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code; + + extern "C" { + fn __gcc_personality_seh0( + exceptionRecord: *mut EXCEPTION_RECORD, + establisherFrame: *mut c_void, + contextRecord: *mut CONTEXT, + dispatcherContext: *mut DISPATCHER_CONTEXT + ) -> EXCEPTION_DISPOSITION; + + fn _GCC_specific_handler( + exceptionRecord: *mut EXCEPTION_RECORD, + establisherFrame: *mut c_void, + contextRecord: *mut CONTEXT, + dispatcherContext: *mut DISPATCHER_CONTEXT, + personality: _Unwind_Personality_Fn + ) -> EXCEPTION_DISPOSITION; + } + + #[lang="eh_personality"] + #[no_mangle] // referenced from rust_try.ll + #[allow(private_no_mangle_fns)] + extern "C" fn rust_eh_personality( + exceptionRecord: *mut EXCEPTION_RECORD, + establisherFrame: *mut c_void, + contextRecord: *mut CONTEXT, + dispatcherContext: *mut DISPATCHER_CONTEXT + ) -> EXCEPTION_DISPOSITION + { + unsafe { + __gcc_personality_seh0(exceptionRecord, establisherFrame, + contextRecord, dispatcherContext) + } + } + + #[no_mangle] // referenced from rust_try.ll + pub extern "C" fn rust_eh_personality_catch( + exceptionRecord: *mut EXCEPTION_RECORD, + establisherFrame: *mut c_void, + contextRecord: *mut CONTEXT, + dispatcherContext: *mut DISPATCHER_CONTEXT + ) -> EXCEPTION_DISPOSITION + { + extern "C" fn inner( + _version: c_int, + actions: uw::_Unwind_Action, + _exception_class: uw::_Unwind_Exception_Class, + _ue_header: *mut uw::_Unwind_Exception, + _context: *mut uw::_Unwind_Context + ) -> uw::_Unwind_Reason_Code + { + if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase + uw::_URC_HANDLER_FOUND // catch! + } + else { // cleanup phase + uw::_URC_INSTALL_CONTEXT + } + } + + unsafe { + _GCC_specific_handler(exceptionRecord, establisherFrame, + contextRecord, dispatcherContext, + inner) + } + } +} + diff --git a/src/libstd/rt/unwind/mod.rs b/src/libstd/rt/unwind/mod.rs new file mode 100644 index 00000000000..576035ffe9a --- /dev/null +++ b/src/libstd/rt/unwind/mod.rs @@ -0,0 +1,319 @@ +// Copyright 2013 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Implementation of Rust stack unwinding +//! +//! For background on exception handling and stack unwinding please see +//! "Exception Handling in LLVM" (llvm.org/docs/ExceptionHandling.html) and +//! documents linked from it. +//! These are also good reads: +//! http://theofilos.cs.columbia.edu/blog/2013/09/22/base_abi/ +//! http://monoinfinito.wordpress.com/series/exception-handling-in-c/ +//! http://www.airs.com/blog/index.php?s=exception+frames +//! +//! ## A brief summary +//! +//! Exception handling happens in two phases: a search phase and a cleanup phase. +//! +//! In both phases the unwinder walks stack frames from top to bottom using +//! information from the stack frame unwind sections of the current process's +//! modules ("module" here refers to an OS module, i.e. an executable or a +//! dynamic library). +//! +//! For each stack frame, it invokes the associated "personality routine", whose +//! address is also stored in the unwind info section. +//! +//! In the search phase, the job of a personality routine is to examine exception +//! object being thrown, and to decide whether it should be caught at that stack +//! frame. Once the handler frame has been identified, cleanup phase begins. +//! +//! In the cleanup phase, personality routines invoke cleanup code associated +//! with their stack frames (i.e. destructors). Once stack has been unwound down +//! to the handler frame level, unwinding stops and the last personality routine +//! transfers control to its catch block. +//! +//! ## Frame unwind info registration +//! +//! Each module has its own frame unwind info section (usually ".eh_frame"), and +//! unwinder needs to know about all of them in order for unwinding to be able to +//! cross module boundaries. +//! +//! On some platforms, like Linux, this is achieved by dynamically enumerating +//! currently loaded modules via the dl_iterate_phdr() API and finding all +//! .eh_frame sections. +//! +//! Others, like Windows, require modules to actively register their unwind info +//! sections by calling __register_frame_info() API at startup. In the latter +//! case it is essential that there is only one copy of the unwinder runtime in +//! the process. This is usually achieved by linking to the dynamic version of +//! the unwind runtime. +//! +//! Currently Rust uses unwind runtime provided by libgcc. + +#![allow(dead_code)] +#![allow(unused_imports)] + +use prelude::v1::*; + +use any::Any; +use boxed; +use cell::Cell; +use cmp; +use panicking; +use fmt; +use intrinsics; +use libc::c_void; +use mem; +use sync::atomic::{self, Ordering}; +use sys_common::mutex::{Mutex, MUTEX_INIT}; + +// The actual unwinding implementation is cfg'd here, and we've got two current +// implementations. One goes through SEH on Windows and the other goes through +// libgcc via the libunwind-like API. +#[cfg(target_env = "msvc")] #[path = "seh.rs"] #[doc(hidden)] +pub mod imp; +#[cfg(not(target_env = "msvc"))] #[path = "gcc.rs"] #[doc(hidden)] +pub mod imp; + +pub type Callback = fn(msg: &(Any + Send), file: &'static str, line: u32); + +// Variables used for invoking callbacks when a thread starts to unwind. +// +// For more information, see below. +const MAX_CALLBACKS: usize = 16; +static CALLBACKS: [atomic::AtomicUsize; MAX_CALLBACKS] = + [atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT, + atomic::ATOMIC_USIZE_INIT, atomic::ATOMIC_USIZE_INIT]; +static CALLBACK_CNT: atomic::AtomicUsize = atomic::ATOMIC_USIZE_INIT; + +thread_local! { static PANICKING: Cell<bool> = Cell::new(false) } + +#[link(name = "rustrt_native", kind = "static")] +#[cfg(not(test))] +extern {} + +/// Invoke a closure, capturing the cause of panic if one occurs. +/// +/// This function will return `Ok(())` if the closure did not panic, and will +/// return `Err(cause)` if the closure panics. The `cause` returned is the +/// object with which panic was originally invoked. +/// +/// This function also is unsafe for a variety of reasons: +/// +/// * This is not safe to call in a nested fashion. The unwinding +/// interface for Rust is designed to have at most one try/catch block per +/// thread, not multiple. No runtime checking is currently performed to uphold +/// this invariant, so this function is not safe. A nested try/catch block +/// may result in corruption of the outer try/catch block's state, especially +/// if this is used within a thread itself. +/// +/// * It is not sound to trigger unwinding while already unwinding. Rust threads +/// have runtime checks in place to ensure this invariant, but it is not +/// guaranteed that a rust thread is in place when invoking this function. +/// Unwinding twice can lead to resource leaks where some destructors are not +/// run. +pub unsafe fn try<F: FnOnce()>(f: F) -> Result<(), Box<Any + Send>> { + let mut f = Some(f); + return inner_try(try_fn::<F>, &mut f as *mut _ as *mut c_void); + + // If an inner function were not used here, then this generic function `try` + // uses the native symbol `rust_try`, for which the code is statically + // linked into the standard library. This means that the DLL for the + // standard library must have `rust_try` as an exposed symbol that + // downstream crates can link against (because monomorphizations of `try` in + // downstream crates will have a reference to the `rust_try` symbol). + // + // On MSVC this requires the symbol `rust_try` to be tagged with + // `dllexport`, but it's easier to not have conditional `src/rt/rust_try.ll` + // files and instead just have this non-generic shim the compiler can take + // care of exposing correctly. + unsafe fn inner_try(f: extern fn(*mut c_void), data: *mut c_void) + -> Result<(), Box<Any + Send>> { + let prev = PANICKING.with(|s| s.get()); + PANICKING.with(|s| s.set(false)); + let ep = rust_try(f, data); + PANICKING.with(|s| s.set(prev)); + if ep.is_null() { + Ok(()) + } else { + Err(imp::cleanup(ep)) + } + } + + extern fn try_fn<F: FnOnce()>(opt_closure: *mut c_void) { + let opt_closure = opt_closure as *mut Option<F>; + unsafe { (*opt_closure).take().unwrap()(); } + } + + extern { + // Rust's try-catch + // When f(...) returns normally, the return value is null. + // When f(...) throws, the return value is a pointer to the caught + // exception object. + fn rust_try(f: extern fn(*mut c_void), + data: *mut c_void) -> *mut c_void; + } +} + +/// Determines whether the current thread is unwinding because of panic. +pub fn panicking() -> bool { + PANICKING.with(|s| s.get()) +} + +// An uninlined, unmangled function upon which to slap yer breakpoints +#[inline(never)] +#[no_mangle] +#[allow(private_no_mangle_fns)] +fn rust_panic(cause: Box<Any + Send + 'static>) -> ! { + rtdebug!("begin_unwind()"); + unsafe { + imp::panic(cause) + } +} + +#[cfg(not(test))] +/// Entry point of panic from the libcore crate. +#[lang = "panic_fmt"] +pub extern fn rust_begin_unwind(msg: fmt::Arguments, + file: &'static str, line: u32) -> ! { + begin_unwind_fmt(msg, &(file, line)) +} + +/// The entry point for unwinding with a formatted message. +/// +/// This is designed to reduce the amount of code required at the call +/// site as much as possible (so that `panic!()` has as low an impact +/// on (e.g.) the inlining of other functions as possible), by moving +/// the actual formatting into this shared place. +#[inline(never)] #[cold] +pub fn begin_unwind_fmt(msg: fmt::Arguments, file_line: &(&'static str, u32)) -> ! { + use fmt::Write; + + // We do two allocations here, unfortunately. But (a) they're + // required with the current scheme, and (b) we don't handle + // panic + OOM properly anyway (see comment in begin_unwind + // below). + + let mut s = String::new(); + let _ = s.write_fmt(msg); + begin_unwind_inner(Box::new(s), file_line) +} + +/// This is the entry point of unwinding for panic!() and assert!(). +#[inline(never)] #[cold] // avoid code bloat at the call sites as much as possible +pub fn begin_unwind<M: Any + Send>(msg: M, file_line: &(&'static str, u32)) -> ! { + // Note that this should be the only allocation performed in this code path. + // Currently this means that panic!() on OOM will invoke this code path, + // but then again we're not really ready for panic on OOM anyway. If + // we do start doing this, then we should propagate this allocation to + // be performed in the parent of this thread instead of the thread that's + // panicking. + + // see below for why we do the `Any` coercion here. + begin_unwind_inner(Box::new(msg), file_line) +} + +/// The core of the unwinding. +/// +/// This is non-generic to avoid instantiation bloat in other crates +/// (which makes compilation of small crates noticeably slower). (Note: +/// we need the `Any` object anyway, we're not just creating it to +/// avoid being generic.) +/// +/// Doing this split took the LLVM IR line counts of `fn main() { panic!() +/// }` from ~1900/3700 (-O/no opts) to 180/590. +#[inline(never)] #[cold] // this is the slow path, please never inline this +fn begin_unwind_inner(msg: Box<Any + Send>, + file_line: &(&'static str, u32)) -> ! { + // Make sure the default failure handler is registered before we look at the + // callbacks. We also use a raw sys-based mutex here instead of a + // `std::sync` one as accessing TLS can cause weird recursive problems (and + // we don't need poison checking). + unsafe { + static LOCK: Mutex = MUTEX_INIT; + static mut INIT: bool = false; + LOCK.lock(); + if !INIT { + register(panicking::on_panic); + INIT = true; + } + LOCK.unlock(); + } + + // First, invoke call the user-defined callbacks triggered on thread panic. + // + // By the time that we see a callback has been registered (by reading + // MAX_CALLBACKS), the actual callback itself may have not been stored yet, + // so we just chalk it up to a race condition and move on to the next + // callback. Additionally, CALLBACK_CNT may briefly be higher than + // MAX_CALLBACKS, so we're sure to clamp it as necessary. + let callbacks = { + let amt = CALLBACK_CNT.load(Ordering::SeqCst); + &CALLBACKS[..cmp::min(amt, MAX_CALLBACKS)] + }; + for cb in callbacks { + match cb.load(Ordering::SeqCst) { + 0 => {} + n => { + let f: Callback = unsafe { mem::transmute(n) }; + let (file, line) = *file_line; + f(&*msg, file, line); + } + } + }; + + // Now that we've run all the necessary unwind callbacks, we actually + // perform the unwinding. + if panicking() { + // If a thread panics while it's already unwinding then we + // have limited options. Currently our preference is to + // just abort. In the future we may consider resuming + // unwinding or otherwise exiting the thread cleanly. + rterrln!("thread panicked while panicking. aborting."); + unsafe { intrinsics::abort() } + } + PANICKING.with(|s| s.set(true)); + rust_panic(msg); +} + +/// Register a callback to be invoked when a thread unwinds. +/// +/// This is an unsafe and experimental API which allows for an arbitrary +/// callback to be invoked when a thread panics. This callback is invoked on both +/// the initial unwinding and a double unwinding if one occurs. Additionally, +/// the local `Thread` will be in place for the duration of the callback, and +/// the callback must ensure that it remains in place once the callback returns. +/// +/// Only a limited number of callbacks can be registered, and this function +/// returns whether the callback was successfully registered or not. It is not +/// currently possible to unregister a callback once it has been registered. +pub unsafe fn register(f: Callback) -> bool { + match CALLBACK_CNT.fetch_add(1, Ordering::SeqCst) { + // The invocation code has knowledge of this window where the count has + // been incremented, but the callback has not been stored. We're + // guaranteed that the slot we're storing into is 0. + n if n < MAX_CALLBACKS => { + let prev = CALLBACKS[n].swap(mem::transmute(f), Ordering::SeqCst); + rtassert!(prev == 0); + true + } + // If we accidentally bumped the count too high, pull it back. + _ => { + CALLBACK_CNT.store(MAX_CALLBACKS, Ordering::SeqCst); + false + } + } +} diff --git a/src/libstd/rt/unwind/seh.rs b/src/libstd/rt/unwind/seh.rs new file mode 100644 index 00000000000..a72c1debe14 --- /dev/null +++ b/src/libstd/rt/unwind/seh.rs @@ -0,0 +1,30 @@ +// Copyright 2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use prelude::v1::*; + +use any::Any; +use intrinsics; +use libc::c_void; + +pub unsafe fn panic(_data: Box<Any + Send + 'static>) -> ! { + intrinsics::abort(); +} + +pub unsafe fn cleanup(_ptr: *mut c_void) -> Box<Any + Send + 'static> { + intrinsics::abort(); +} + +#[lang = "eh_personality"] +#[no_mangle] +pub extern fn rust_eh_personality() {} + +#[no_mangle] +pub extern fn rust_eh_personality_catch() {} |