如何知道程序是否通过信号结束执行？

Question

我正在编写一个程序监视器作为操作系统课程的作业(非常基本,就像它的介绍).

监视器必须做的事情之一是显示它正在监视的程序的终止代码,如果它以"自然原因"或负责终止它的信号代码结束.

现在我只是等待孩子结束执行然后捕获终止代码.这是相关的代码段:

pid_t id = -1;
switch (id = fork()) {
    // Error when forking:
    case -1:
        error(-1, "Something went wrong when forking.");
        exit(-1);
    // Code for the child process:
    case 0:
        // Just launch the program we're asked to:
        execvp(argv[2], &argv[2]);
        // If reached here it wasn't possible to launch the process:
        error(1, "Process could not be launched.");
        exit(1);
    // Code for the parent process:
    default:
        // Just wait for the child to finish its execution:
        wait(&return_value);
}

error(2) 是一个记录器功能,只是为了在出现错误时简化代码.

取决于我必须如何显示不同的陈述过程:

Process ended: X

要么

Process terminated with signal X.

其中X将是终止代码或接收到的信号.我们怎么知道儿童过程是否因信号而结束？

Answer 1

来自wait(2):

   WIFSIGNALED(status)
          returns true if the child process was terminated by a signal.
   WTERMSIG(status)
          returns  the  number  of the signal that caused the child process to terminate.

所以你需要检查WIFSIGNALED(return_value)一下是否属实,请检查WTERMSIG(return_value).