带有getchar()的SIGINT

Question

我对C很陌生，我正在尝试编写一个迷你程序，当我遇到一个SIGINT时，它应该停止子进程(作为运行exec的叉子)或跳回循环的开始(打印出currentdir/>并等待输入)。目前，为了处理SIGINT，我必须在^C之后点击enter，但理想情况下，我不应该这样做。任何对此问题的帮助都将不胜感激！

volatile sig_atomic_t interrupted = 0; //interrupted is originally set to false.

void sig_handler(int sig)
{
    interrupted = 1;
    //printf("\n");
}

int main_helper()
{
    struct sigaction sa;

    memset(&sa, 0, sizeof(struct sigaction));
    sa.sa_handler = sig_handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;

    if (sigaction(SIGINT, &sa, NULL) == -1)
    {
        fprintf(stderr, "Error: Cannot register signal handler. %s.\n", strerror(errno));
        exit(1);
    }
    
    /* code to get current directory and print it in the format [dir/]> */

    while (is_exit == 0) //because no booleans
    {
        /*
            getting user input.
        */
        input_str = malloc(sizeof(char)); //starting out w a str of length 1.

        if (input_str == NULL)
        { //if the malloc fails for some reason.
            fprintf(stderr, "Error: malloc() failed. %s.\n", strerror(errno));
            exit(1);
        }

        int c; //the character that we're at
        int i = 0;
        //read chars until null term or eof found
        while ((c = getchar()) != '\n')
        {
            if (c == EOF)
            {
                fprintf(stderr, "Error: Failed to read from stdin. %s.\n", strerror(errno));
                exit(1);
            }
            input_str[i++] = c;
            input_str = realloc(input_str, i + 1); //adding space for another

            if (input_str == NULL)
            { //if it can't realloc for some reason.
                fprintf(stderr, "Error: realloc() failed. %s.\n", strerror(errno));
                exit(1);
            }
        }
        input_str[i] = '\0'; //adding null terminator at the end.
        
        /*
            dealing with the input using exec or built-in functions
        */

        free(input_str); //free the input that we just realloced stuff for

        interrupted = 0;

    }
    return EXIT_SUCCESS;
}

现在，我不完全确定为什么会发生这种情况，但是如果我正确地理解了其他一些StackOverflow线程，getchar()函数可能会阻塞SIGINT，直到按enter之后。有人知道怎么解决这个问题吗？使用setjmp/longjmp会有帮助吗？如果他们能解决这些问题，我将如何实现？

Answer 1

我不确定SIGINT，但您可以使用fread编写一个非阻塞的getchar。

unsigned char buffer;
while (fread(&buffer, sizeof(buffer), 1, stdin) == 0) {
    // Check signal in here
    
    // If no character was read, check if it was due to EOF or an error
    if (feof(stdin)) {
        // We reached the end of the file
    }

    if (ferror(stdin)) {
        // An error occurred when we tried to read from stdin
    }
}