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// 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.
//! Unwinding implementation of top of native Win64 SEH,
//! however the unwind handler data (aka LSDA) uses GCC-compatible encoding.
#![allow(bad_style)]
#![allow(private_no_mangle_fns)]
use prelude::v1::*;
use any::Any;
use self::EXCEPTION_DISPOSITION::*;
use sys_common::dwarf::eh;
use core::mem;
use core::ptr;
use libc::{c_void, c_ulonglong, DWORD, LPVOID};
type ULONG_PTR = c_ulonglong;
// Define our exception codes:
// according to http://msdn.microsoft.com/en-us/library/het71c37(v=VS.80).aspx,
// [31:30] = 3 (error), 2 (warning), 1 (info), 0 (success)
// [29] = 1 (user-defined)
// [28] = 0 (reserved)
// we define bits:
// [24:27] = type
// [0:23] = magic
const ETYPE: DWORD = 0b1110_u32 << 28;
const MAGIC: DWORD = 0x525354; // "RST"
const RUST_PANIC: DWORD = ETYPE | (1 << 24) | MAGIC;
const EXCEPTION_NONCONTINUABLE: DWORD = 0x1; // Noncontinuable exception
const EXCEPTION_UNWINDING: DWORD = 0x2; // Unwind is in progress
const EXCEPTION_EXIT_UNWIND: DWORD = 0x4; // Exit unwind is in progress
const EXCEPTION_STACK_INVALID: DWORD = 0x8; // Stack out of limits or unaligned
const EXCEPTION_NESTED_CALL: DWORD = 0x10; // Nested exception handler call
const EXCEPTION_TARGET_UNWIND: DWORD = 0x20; // Target unwind in progress
const EXCEPTION_COLLIDED_UNWIND: DWORD = 0x40; // Collided exception handler call
const EXCEPTION_UNWIND: DWORD = EXCEPTION_UNWINDING |
EXCEPTION_EXIT_UNWIND |
EXCEPTION_TARGET_UNWIND |
EXCEPTION_COLLIDED_UNWIND;
#[repr(C)]
pub struct EXCEPTION_RECORD {
ExceptionCode: DWORD,
ExceptionFlags: DWORD,
ExceptionRecord: *const EXCEPTION_RECORD,
ExceptionAddress: LPVOID,
NumberParameters: DWORD,
ExceptionInformation: [ULONG_PTR; 15],
}
pub enum CONTEXT {}
pub enum UNWIND_HISTORY_TABLE {}
#[repr(C)]
pub struct RUNTIME_FUNCTION {
BeginAddress: DWORD,
EndAddress: DWORD,
UnwindData: DWORD,
}
#[repr(C)]
pub struct DISPATCHER_CONTEXT {
ControlPc: LPVOID,
ImageBase: LPVOID,
FunctionEntry: *const RUNTIME_FUNCTION,
EstablisherFrame: LPVOID,
TargetIp: LPVOID,
ContextRecord: *const CONTEXT,
LanguageHandler: LPVOID,
HandlerData: *const u8,
HistoryTable: *const UNWIND_HISTORY_TABLE,
}
#[repr(C)]
#[derive(Copy, Clone)]
pub enum EXCEPTION_DISPOSITION {
ExceptionContinueExecution,
ExceptionContinueSearch,
ExceptionNestedException,
ExceptionCollidedUnwind
}
// From kernel32.dll
extern "system" {
#[unwind]
fn RaiseException(dwExceptionCode: DWORD,
dwExceptionFlags: DWORD,
nNumberOfArguments: DWORD,
lpArguments: *const ULONG_PTR);
fn RtlUnwindEx(TargetFrame: LPVOID,
TargetIp: LPVOID,
ExceptionRecord: *const EXCEPTION_RECORD,
ReturnValue: LPVOID,
OriginalContext: *const CONTEXT,
HistoryTable: *const UNWIND_HISTORY_TABLE);
}
#[repr(C)]
struct PanicData {
data: Box<Any + Send + 'static>
}
pub unsafe fn panic(data: Box<Any + Send + 'static>) -> ! {
let panic_ctx = Box::new(PanicData { data: data });
let params = [Box::into_raw(panic_ctx) as ULONG_PTR];
RaiseException(RUST_PANIC,
EXCEPTION_NONCONTINUABLE,
params.len() as DWORD,
¶ms as *const ULONG_PTR);
rtabort!("could not unwind stack");
}
pub unsafe fn cleanup(ptr: *mut u8) -> Box<Any + Send + 'static> {
let panic_ctx = Box::from_raw(ptr as *mut PanicData);
return panic_ctx.data;
}
// SEH doesn't support resuming unwinds after calling a landing pad like
// libunwind does. For this reason, MSVC compiler outlines landing pads into
// separate functions that can be called directly from the personality function
// but are nevertheless able to find and modify stack frame of the "parent"
// function.
//
// Since this cannot be done with libdwarf-style landing pads,
// rust_eh_personality instead catches RUST_PANICs, runs the landing pad, then
// reraises the exception.
//
// Note that it makes certain assumptions about the exception:
//
// 1. That RUST_PANIC is non-continuable, so no lower stack frame may choose to
// resume execution.
// 2. That the first parameter of the exception is a pointer to an extra data
// area (PanicData).
// Since these assumptions do not generally hold true for foreign exceptions
// (system faults, C++ exceptions, etc), we make no attempt to invoke our
// landing pads (and, thus, destructors!) for anything other than RUST_PANICs.
// This is considered acceptable, because the behavior of throwing exceptions
// through a C ABI boundary is undefined.
#[lang = "eh_personality_catch"]
#[cfg(not(test))]
unsafe extern fn rust_eh_personality_catch(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: LPVOID,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT
) -> EXCEPTION_DISPOSITION
{
rust_eh_personality(exceptionRecord, establisherFrame,
contextRecord, dispatcherContext)
}
#[lang = "eh_personality"]
#[cfg(not(test))]
unsafe extern fn rust_eh_personality(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: LPVOID,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT
) -> EXCEPTION_DISPOSITION
{
let er = &*exceptionRecord;
let dc = &*dispatcherContext;
if er.ExceptionFlags & EXCEPTION_UNWIND == 0 { // we are in the dispatch phase
if er.ExceptionCode == RUST_PANIC {
if let Some(lpad) = find_landing_pad(dc) {
RtlUnwindEx(establisherFrame,
lpad as LPVOID,
exceptionRecord,
er.ExceptionInformation[0] as LPVOID, // pointer to PanicData
contextRecord,
dc.HistoryTable);
rtabort!("could not unwind");
}
}
}
ExceptionContinueSearch
}
// The `resume` instruction, found at the end of the landing pads, and whose job
// is to resume stack unwinding, is typically lowered by LLVM into a call to
// `_Unwind_Resume` routine. To avoid confusion with the same symbol exported
// from libgcc, we redirect it to `rust_eh_unwind_resume`.
// Since resolution of this symbol is done by the linker, `rust_eh_unwind_resume`
// must be marked `pub` + `#[no_mangle]`. (Can we make it a lang item?)
#[lang = "eh_unwind_resume"]
#[cfg(not(test))]
#[unwind]
unsafe extern fn rust_eh_unwind_resume(panic_ctx: LPVOID) {
let params = [panic_ctx as ULONG_PTR];
RaiseException(RUST_PANIC,
EXCEPTION_NONCONTINUABLE,
params.len() as DWORD,
¶ms as *const ULONG_PTR);
rtabort!("could not resume unwind");
}
unsafe fn find_landing_pad(dc: &DISPATCHER_CONTEXT) -> Option<usize> {
let eh_ctx = eh::EHContext {
ip: dc.ControlPc as usize,
func_start: dc.ImageBase as usize + (*dc.FunctionEntry).BeginAddress as usize,
text_start: dc.ImageBase as usize,
data_start: 0
};
eh::find_landing_pad(dc.HandlerData, &eh_ctx)
}
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