1、使用signal()函数和sigaction()
signal()函数原型
#include <signal.h>
typedef void (*sighandler_t)(int);
sighandler_t signal(int signum, sighandler_t handler);
signal() sets the disposition of the signal signum to handler, which is
either SIG_IGN, SIG_DFL, or the address of a programmer-defined function (a "signal handler")
The signals SIGKILL and SIGSTOP cannot be caught or ignored. ——即信号SIGKILL和信号SIGSTOP不能被捕获或者忽略。sigaction()函数原型
NAME
<pre> sigaction - examine and change a signal action
SYNOPSIS
#include <signal.h>
int sigaction(int signum, const struct sigaction *act,
struct sigaction *oldact);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sigaction(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE
If act is non-NULL, the new action for signal signum is installed from
act. If oldact is non-NULL, the previous action is saved in oldact.
The sigaction structure is defined as something like:
struct sigaction {
void (*sa_handler)(int);
void (*sa_sigaction)(int, siginfo_t *, void *);
sigset_t sa_mask;
int sa_flags;
void (*sa_restorer)(void);
};
On some architectures a union is involved: do not assign to both
sa_handler and sa_sigaction.
The sa_restorer element is obsolete and should not be used. POSIX does
not specify a sa_restorer element.
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
/* Define the signal handle function */
void my_func(int sig_no)
{
switch(sig_no)
{
case SIGINT:
printf("I have get SIGINT\n");
break;
case SIGQUIT:
printf("I have get SIGQUIT\n");
break;
default:
break;
}
}
int main()
{
struct sigaction action;
printf("Waiting for signal SIGINT or SIGQUIT...\n");
/* Initialize the sigaction structure*/
action.sa_handler = my_func;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
/* Send certain signal and go to handle_fun */
sigaction(SIGINT, &action, 0);
sigaction(SIGQUIT, &action, 0);
pause();
alarm(3);
printf("I'm over!\n");
exit(0);
}
2、使用信号集函数组
调用的函数主要包括一下4个功能模块，创建信号集、注册信号处理函数及检测信号。 sigemptyset()：将信号集初始化为空 sigfillset(): 将信号集初始化为包含所有已定义的信号集。 sigaddset()： 将制定信号加入信号集中。 sigdelset(): 将指定信号从信号集中删除。 sigismember(): 查询指定信号是否在信号集中。 sigpending()函数允许进程检测“未处理“的信号，并进一步决定对它们做何处理。 说明： 注册信号处理函数主要用于决定进程如何处理信号，注意：信号集中的信号并不是真正可以处理的信号，只有当信号的状态处于非阻塞状态时才会真正起作用。所以一般使用sigprocmask()函数检测并更改信号屏蔽字（信号屏蔽字是指用来指定当前被阻塞的一组信号，它们不会被进程接收），然后使用sigaction()函数来定义进程接收到特定信号的行为。 信号处理的一般流程：
程序实例：
首先把SIGQUIT、SIGINT两个信号加入信号集，然后将该信号集设为阻塞状态，并进入用户输入状态。用户只需按任意键就可以立即将信号集设为非阻塞状态，再对这两个信号分别进行操作，其中SIGQUIT执行默认操作，而SIGINT执行用户自定义函数的操作。
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/types.h>
/* Define the signal handle function */
void my_func(int sig_no)
{
printf("If you want to quit, please try SIGQUIT\n");
}
int main()
{
sigset_t set, pendset;
struct sigaction action1, action2;
/* step1: Initialize the sigset with Null. */
if(sigemptyset(&set) < 0)
{
perror("sigemptyset");
exit(1);
}
/* Add certain signal to sigset */
if(sigaddset(&set, SIGQUIT) < 0)
{
perror("sigaddset");
exit(1);
}
if(sigaddset(&set, SIGINT) < 0)
{
perror("sigaddset");
exit(1);
}
if(sigismember(&set, SIGINT) < 0)
{
sigemptyset(&action1.sa_mask);
action1.sa_handler = my_func;
action1.sa_flags = 0;
sigaction(SIGINT, &action1, NULL);
}
if(sigismember(&set, SIGQUIT) < 0)
{
sigemptyset(&action2.sa_mask);
action2.sa_handler = my_func;
action2.sa_flags = 0;
sigaction(SIGQUIT, &action2, NULL);
}
/* step2: Set the value of mask word */
if(sigprocmask(SIG_BLOCK, &set, NULL) < 0)
{
perror("sigprocmask");
exit(1);
}
else
{
printf("Signal set was blocked, Press any key!\n");
getchar();
}
/* Delete the signal of set */
if(sigprocmask(SIG_UNBLOCK, &set, NULL) < 0)
{
perror("sigprocmask");
exit(1);
}
else
{
printf("Signal set was unblocked, Press any key!\n");
}
while(1);
exit(0);
}
时间： 2024-10-12 12:35:31