libunwind/test/forceunwind.pass.cpp

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// REQUIRES: linux

// TODO: Figure out why this fails with Memory Sanitizer.
// XFAIL: msan

// Basic test for _Unwind_ForcedUnwind.
// See libcxxabi/test/forced_unwind* tests too.

#undef NDEBUG
#include <assert.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <unwind.h>

// Using __attribute__((section("main_func"))) is Linux specific, but then
// this entire test is marked as requiring Linux, so we should be good.
//
// We don't use dladdr() because on musl it's a no-op when statically linked.
extern char __start_main_func;
extern char __stop_main_func;

void foo();
_Unwind_Exception ex;

_Unwind_Reason_Code stop(int version, _Unwind_Action actions,
                         _Unwind_Exception_Class exceptionClass,
                         _Unwind_Exception *exceptionObject,
                         struct _Unwind_Context *context,
                         void *stop_parameter) {
  assert(version == 1);
  assert((actions & _UA_FORCE_UNWIND) != 0);
  (void)exceptionClass;
  assert(exceptionObject == &ex);
  assert(stop_parameter == &foo);

  // Unwind until the main is reached, above frames depend on the platform and
  // architecture.
  uintptr_t ip = _Unwind_GetIP(context);
  if (ip >= (uintptr_t)&__start_main_func &&
      ip < (uintptr_t)&__stop_main_func) {
    _Exit(0);
  }

  return _URC_NO_REASON;
}

__attribute__((noinline)) void foo() {

  // Arm EHABI defines struct _Unwind_Control_Block as exception
  // object. Ensure struct _Unwind_Exception* work there too,
  // because _Unwind_Exception in this case is just an alias.
  struct _Unwind_Exception *e = &ex;
#if defined(_LIBUNWIND_ARM_EHABI)
  // Create a mock exception object.
  memset(e, '\0', sizeof(*e));
  memcpy(&e->exception_class, "CLNGUNW", sizeof(e->exception_class));
#endif
  _Unwind_ForcedUnwind(e, stop, (void *)&foo);
}

__attribute__((section("main_func"))) int main() {
  foo();
  return -2;
}