谁在按 ctrl+c、tty 驱动程序或 shell 时将 SIGINT 发送到前台进程

Question

当我在登录 shell 执行命令时按 ctrl+c 时，前台进程被终止。
谁发出信号？

TTY 驱动程序是否直接向前台进程组发送 SIGINT？
或者 TTY 驱动程序是否将 SIGINT 发送到 shell 并且 shell 将信号重定向到前台进程组？

Answer 1

tty 驱动程序（特别是线路规程）会将信号直接发送到前台进程组。这是代码 from Linux，您可以在其中看到它只是获取前景组并向其发出信号：

/**
 *  [...]
 *      Called when a signal is being sent due to terminal input.
 *  [...]
 */

static void __isig(int sig, struct tty_struct *tty)
{
        struct pid *tty_pgrp = tty_get_pgrp(tty);
        if (tty_pgrp) {
                kill_pgrp(tty_pgrp, sig, 1);
                put_pid(tty_pgrp);
        }
}

这是从同一文件中的输入处理函数调用的，其中 n_tty_receive_signal_char 距离调用 __isig:

仅几步之遥

/**
 *  [...]
 *  Process an individual character of input received from the driver.
 *  This is serialized with respect to itself by the rules for the
 *  driver above.
 *  [...]
 */

static int
n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
{
    struct n_tty_data *ldata = tty->disc_data;

    /* [...] */

    if (L_ISIG(tty)) {
        if (c == INTR_CHAR(tty)) {
            n_tty_receive_signal_char(tty, SIGINT, c);
            return 0;
        } else if (c == QUIT_CHAR(tty)) {
            n_tty_receive_signal_char(tty, SIGQUIT, c);
            return 0;
        } else if (c == SUSP_CHAR(tty)) {
            n_tty_receive_signal_char(tty, SIGTSTP, c);
            return 0;
        }
    }

谁在按 ctrl+c、tty 驱动程序或 shell 时将 SIGINT 发送到前台进程

who send SIGINT to foreground process when press ctrl+c, tty driver or shell

linux

bash

signals

linux-kernel

sigint