如何生成始终触发信号 SIGFPE(div by zero) 的代码? [英] How to produce codes that always trigger signal SIGFPE(div by zero)?

问题描述

我需要编写一个单元测试，它应该总是触发除以零信号 (SIGFPE)，这样我就可以测试和比较有/没有我的信号捕获模块会发生什么.

I need to code a unit-test that should always trigger a divied by zero signal(SIGFPE), so I can test and compare what would happen with/without my signal catching module.

我的 Linux 信号捕获/恢复模块已经开发完成，并按预期工作.当我为模块编写单元测试时，我遇到了一个小麻烦.

My Linux signal catching/resuming module has been developed, and worked as expecting. When I'm coding the unit-test for the module, I encounter a small trouble.

这些是 UT 代码(通过 GTest):

These are the UT codes(by means of GTest):

int do_div_by_0() {
    int j = 0;
    return 123 / j; /* During release-buidling, this div-op would be optimized out,
                       although it would be not when debug-building! */
};

TEST_F( SignalsHandling_F, divByZeroDying ) {
   ASSERT_EXIT( {
      do_div_by_0();
      
      // never should go here!
      exit( EXIT_SUCCESS );

   }, KilledBySignal( SIGFPE ), "" );
};

如果所有代码都是在调试模式下构建的，那就没有问题.但是在Release模式下除法运算会被优化掉，因此SIGFPE信号永远不会被触发！

If all codes are built in Debug mode, there's no problem. But the division operation would be optimized out in Release mode, as a result the SIGFPE signal would Never be triggered!

为了保持产品代码和测试代码之间的一致性，我必须在发布产品时以发布模式构建它们.

To keep the consistency between product codes and testing codes, I must build them all in release mode when I release my product.

如何编写一段始终触发信号SIGFPE的代码?

How to compose a piece of code that always trigger the signal SIGFPE?

如果更实际"，我不想使用 raise() 函数方法存在，因为我想实际触发 SIGFPE 信号.

I don't want to use raise() function if a more "actual" method exists, because I want to actually trigger out SIGFPE signal.

谢谢！请原谅我糟糕的英语！

Thanks! Pls forgive my poor English!

推荐答案

我认为 ChrisDodd 的答案是最准确的.IE.忽略 do_div_by_0 的返回值，以便编译器优化除法运算.

I think that ChrisDodd's answer is the most precise one. I.e. the return value of do_div_by_0 is ignored, so that the compiler optimizes out the division operation.

调用do_div_by_0时需要用到返回值，如下:

We need to use the return value when we call do_div_by_0, like follows:

TEST_F( SignalsHandling_F, divByZeroDying ) {
   ASSERT_EXIT( {
      std::cerr << do_div_by_0();
      
      // never should go here!
      exit( EXIT_SUCCESS );

   }, KilledBySignal( SIGFPE ), "" );
};

有效！

谢谢大家！！！

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