c – 为什么在调试时会产生程序退出代码改变？

我有一个C程序,我用来测试另一个程序不会崩溃.父代码(我们称之为’parentProg’)看起来像这样：

int run(const char * command)
{
  ...

  int retCode = system(command);
  printf("Code is %d\n",retCode);
  if(retCode == 134) //128 + SIGABORT
  {
    // Record error conditions
    ...
  }
}

命令变量包含正在测试的程序(我们称之为’childProg’).使用以前的Linux发行版,此代码按预期工作.如果a.out崩溃或命中一个断言,它将返回134并且错误处理代码将运行.但是,在我升级到更新的Linux发行版后,情况就不再如此了.相反,当使用GDB或nemiver作为衍生程序运行时,我看到返回代码为6.奇怪的是,如果我单独运行子程序或使用DDD,它将恢复到134.

对于以下测试,我将childProg修改为仅以下代码：

#include <assert.h>

int main(int argc, char * argv[])
{
  assert(0);
  return 0;
}

childProg本身

[user@localhost multi]$./childProg 
childProg: temp.cpp:5: int main(int, char **): Assertion `0' failed.
Abort
[user@localhost multi]$echo $?
134

parentProg产生childProg

[user@localhost multi]$./parentProg 1 o
Running 1 times
childProg: temp.cpp:5: int main(int, char **): Assertion `0' failed.
Code is 6
Done 0
[user@localhost multi]$

使用GDB

(gdb) run
Starting program: parentProg 1 o
Running 1 times
Detaching after fork from child process 3311.
childProg: temp.cpp:5: int main(int, char **): Assertion `0' failed.
Code is 6
Done 0
[Inferior 1 (process 3295) exited normally]
(gdb) 

有了DDD

(gdb) run 1 o
Starting program: parentProg 1 o
Running 1 times
Detaching after fork from child process 3336.
childProg: temp.cpp:5: int main(int, char **): Assertion `0' failed.
Code is 134
Done 0
[Inferior 1 (process 3319) exited normally]
(gdb) 

这按预期工作

[me@localhost multi]$/bin/sh -c ./childProg
childProg: temp.cpp:5: int main(int, char **): Assertion `0' failed.
Abort
[me@localhost multi]$echo $?
134

这可能会发生什么？除了检查退出代码之外,还有更好的方法来检查崩溃/段错误/断言吗？

解决方法:

< sys / wait.h>头文件包含用于分析返回码的宏.

要检查退出的原因,您可以执行以下操作：

#include <stdio.h>
#include <sys/wait.h>

...

void run(const char *command)
{
    int retcode = system(command);

    if (WIFEXITED(retcode))
    {
        int status = WEXITSTATUS(retcode);
        if (status)
        {
            printf("Exited normally with FAILURE status of %d!\n", status);
        }
        else
        {
            printf("Exited normally with SUCCESS(0) status!\n");
        }
    }
    else if (WIFSIGNALED(retcode))
    {
        int signal = WTERMSIG(retcode);
        printf("Abnormal termination - program crashed or was aborted with signal %d\n", signal);
    }

}

有关这些宏的说明,请参阅“man waitpid”.

标签：c-2,c-3,linux,assert,exit-code
来源： https://codeday.me/bug/20190612/1228647.html