文章目录sigaction 函数原型sigaction 函数功能sigqueue 函数原型sigqueue 函数功能一些经验示例signalsigaction 和 sigqueue CP交互sigactionsigqueuesigaction 函数原型int sigaction(int signum, const struct sigaction *act,struct sigaction *oldact);sigaction 函数功能•函数功能给信号设置新的注册函数act同时保留原有的信号处理函数在oldact–执行某些信号时屏蔽某些信号直接给sa_mask赋值即可–处理带参数的信号–一次注册长期有效struct sigaction { void (*sa_handler)(int); void (*sa_sigaction)(int, siginfo_t *, void *); sigset_t sa_mask; int sa_flags; void (*sa_restorer)(void); };sigqueue 函数原型int sigqueue (pid_t pid, int sig, const union sigval value);sigqueue 函数功能–用法与kill类似 –与kill不同之处kill可以将 pid 设置为指定负值向整个进程发送信号 –可以给指定进程传递一个int型数据 –sigaction 和 sigqueue 是一对 CP一些经验•一旦给信号安装了handler它就一直有效•信号的handler存在并发访问、可重入问题•在信号的handler运行期间会阻塞掉当前本身该信号•在handler运行期间当前信号的多次提交可能被丢弃只保留一次•除了本身信号是被阻塞的可以通过设置阻塞设定的一些信号•signal是标准C定义的函数而sigaction是POSIX接口函数•Signal是对sigaction的封装•不同的架构、操作系统对信号的value、default action 可能不一样•特殊的两个信号SIGKILL和SIGSTOP–不能被忽略–不能安装signal handler、不能被捕捉–不能被阻塞示例signal#include signal.h #include unistd.h #include stdio.h void handler (int signo) { int i,j; switch (signo) { case SIGHUP: printf (get a SIGHUP signal: %d\n, signo); break; case SIGINT: printf (get a SIGINT signal: %d\n, signo); break; case SIGQUIT: printf (get a SIGQUIT signal: %d\n, signo); break; case SIGUSR1: printf (get a SIGUSR1 signal: %d\n, signo); break; default: printf (unknow signal\n); } for (i 0; i 10000; i) { for (j 0; j 1000; j) ; } printf (handler exit with signo: %d\n, signo); } int main (void) { signal (SIGHUP, handler); signal (SIGINT, handler); signal (SIGQUIT, handler); signal (SIGUSR1, handler); while (1); return 0; } //test 1: // run: kill -HUP 22380 // run: kill -HUP 22380 // run: kill -HUP 22380 // run: kill -HUP 22380 // run: kill -HUP 22380 //test 2: // run: kill -HUP 22380 // run: kill -INT 22380 // run: kill -QUIT 22380 // run: kill -USR1 22380 // run: kill -HUP 22380sigaction 和 sigqueue CP交互sigaction#include unistd.h #include signal.h #include stdio.h void signal_handler (int signum) { printf (signal_handler\n); switch (signum) { case SIGHUP: printf (get signal: SIGHUP\n); sleep (20); break; case SIGINT: printf (get signal: SIGINT\n); break; case SIGQUIT: printf (get signal: SIGQUIT\n); break; case SIGUSR1: printf (get signal: SIGUSR1\n); break; default: printf (undefined signal\n); } } void signal_sigaction (int signum, siginfo_t *parm, void *parm2) { printf (signal_sigaction\n); switch (signum) { case SIGHUP: printf (get signal: SIGHUP\n); break; case SIGINT: printf (get signal: SIGINT\n); break; case SIGQUIT: printf (get signal: SIGQUIT\n); break; case SIGUSR1: printf (get signal: SIGUSR1\n); } printf (received data: %d\n, parm-si_value); printf (sending signal process pid : %d\n, parm-si_pid); } int main (void) { struct sigaction act, old_act; act.sa_sigaction signal_sigaction; act.sa_handler signal_handler; sigemptyset (act.sa_mask); sigaddset (act.sa_mask, SIGUSR1); act.sa_flags 0; //sa_flags must be set,or it will cause core dump //set 0 may cause signal losing //act.sa_flags SA_RESETHAND | SA_NODEFER; //SA_RESETHAND: restore signal action to DEF //SA_SIGINFO: use sa_sigaction as signal handler //SA_NODEFER: umask sa_mask sigaction (SIGHUP, act, old_act); // sigaction (SIGINT, act, old_act); // sigaction (SIGQUIT, act, old_act); // sigaction (SIGUSR1, act, old_act); while (1); return 0; }sigqueue#include stdio.h #include stdlib.h #include unistd.h #include signal.h int main (int argc, char *argv[]) { union sigval val; val.sival_int 10; pid_t pid atoi (argv[1]); if (sigqueue (pid, SIGHUP, val) -1) { perror (sigqueue); exit (EXIT_FAILURE); } printf (current pid:%d\n, getpid()); return 0; }