C: Linux C 编程 - 信号量

信号量

semget

函数原型

int semget(key_t key, int nsems, int semflg);

 

信号量操控

semctl

函数原型

int semctl(int semid, int semnum, int cmd, ...);

 

信号量操作

semop

函数原型

int semop(int semid, struct sembuf *sops, unsigned nsops);

 

semtimedop

函数原型

int semtimedop(int semid, struct sembuf *sops, unsigned nsops, struct timespec *timeout);

 

 

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

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>

int semid;

void do_exit()
{  
  if (semctl(semid, -1, IPC_RMID) == -1)
  {
    printf("semctl error\n");
    return;
  }
  printf("exit.\n");
  exit(0);
}

void on_signal_int(int sig)
{
  printf("signal: num=SIGINT(%d)\n", sig);
  do_exit();
}

void on_signal_term(int sig)
{
  printf("signal: num=SIGTERM(%d)\n", sig);
  do_exit();
}

void on_signal_kill(int sig)
{
  printf("signal: num=SIGKILL(%d)\n", sig);
  do_exit();
}

int main(int argc, char** argv)
{
  // SIGINT signal
  signal(SIGINT, on_signal_int);
  signal(SIGTERM, on_signal_term);
  
  // The signals SIGKILL and SIGSTOP cannot be caught or ignored.
  // signal(SIGKILL, on_signal_kill);  

  semid = semget((key_t) 6, 1, 0666 | IPC_CREAT | IPC_EXCL);
  if (semid == -1)
  {
    printf("%s is running...\n", argv[0]);
    return 0;
  }

  while (1)
  {
    
  }

  on_signal_int(SIGINT);
  return 0;
}