semaphore.c

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#include <unistd.h>
#include <sys/types.h>
#include <sys/sem.h>
#include <stdio.h>
#include "stdlib.h"

int semaphore_wait(int id, int idx)
{
  struct sembuf sem_op;   

		sem_op.sem_num = idx;   
		sem_op.sem_op = -1;   
		sem_op.sem_flg = SEM_UNDO ;//| IPC_NOWAIT;   
		return semop(id, &sem_op, 1) ;	

}
 int semaphore_signal(int id, int idx)
{
   struct   sembuf   sem_op;   
   sem_op.sem_num = idx;   
   sem_op.sem_op = 1;   
   sem_op.sem_flg = SEM_UNDO;   
   if(semop(id, &sem_op, 1) < 0)
		return -1;
	return 0;
}

int semaphore_create(key_t sem_key,int n)
{
	unsigned long sem_id;
	int ret;
	sem_id = semget(sem_key, n, IPC_CREAT | 0600);  
	return sem_id;

}

void semaphore_set_val(int id,int idx,int val)
{
	 int ret;
	 ret = semctl(id, idx, SETVAL, val);   // 设置互斥信号量初值
	if(ret < 0)
	{
		return -1;
	}
}
void semaphore_destroy(int  id)
{
	semctl(id,0,IPC_RMID,0);
}
void semaphore_state(int id)
{
	printf("SERVER:semaphore:0x%x\n",semctl(id, 0, GETVAL, 0 ));	
}