c - C 中 while 循环中的 Fork 炸弹，在退出程序后发生

Question

`#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv){
    int pid = 0;
    int forever;
    static char s; //Uses simply s in the while loop, press s once for each process to
//terminate each process
    //char *s; This can't work because it always points to the start of a char array.
//I don't know why. int * doesn't do that.
    pid = fork();
    if(pid>0)// a child cannot see it's own process ID so pid would be 0 if it was the
child
        printf("This is the parent.\n");
    else if(pid == 0) printf("This is the child.\n");
    while(s != 's'){//One quote is a character, two quotes is a char array
        forever = fork();
        if(forever>0)
            printf("Parent process\n");
        else printf("Child process\n");
        s = getchar();//I tried making this *s but it causes a segmentation fault
    }
    return 0;
}`

这导致了一个问题。当我从终端执行程序时，我可以通过为每个进程输入一次“s”来退出程序，然后终端恢复正常。或者看起来是这样。当我在终端按下“向上”箭头时，我进入无限循环并得到 fork 炸弹。我该如何避免这种情况？

Answer 1

更改s至

int s = 0;

因为getchar返回 int 并且你确实需要它。使其静态也没有意义(这里也没有坏处，只是糟糕/不寻常的风格)。请注意，您现在需要初始化，这与静态时不同。

然后检查getchar错误/EOF 的返回值，<0并就此终止。这应该可以修复 fork 炸弹，因为它很可能是由 getchar 引起的开始立即返回错误。添加打印以查看发生了什么，特别是打印错误消息或 EOF 状态。

您还应该检查 fork以防万一，也返回错误值。