进程同步

实现一个简单的进程同步程序

#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <semaphore.h>
int *pbuff=0;
sem_t *s1,*s2;

int main()
{
  //printf("Hello World!
");
  int pid=0;
  int tc,tf;
  pbuff=(int *)mmap(0,sizeof(int),PROT_READ|PROT_WRITE,
		  MAP_SHARED|MAP_ANON,-1,0);
  s1=(sem_t *)mmap(0,sizeof(sem_t),PROT_READ|PROT_WRITE,
		  MAP_SHARED|MAP_ANON,-1,0);
  s2=(sem_t *)mmap(0,sizeof(sem_t),PROT_READ|PROT_WRITE,
		  MAP_SHARED|MAP_ANON,-1,0);
  *pbuff=0;
  sem_init(s1,1,1);
  sem_init(s2,1,0);
  pid=fork();
  if(pid==0)
  {
  l: tc=*pbuff;
	 tc++;
	 sem_wait(s1);
	 *pbuff=tc;
	 sem_post(s2);
	 if(tc>=10)
		 return 0;
	 else goto l;
  }
  else if(pid>0)
  {
   L: sem_wait(s2);
	  tf=*pbuff;
	  sem_post(s1);
	  if(tf>0)
	      printf("%d
",tf);
      if(tf==10)
		  return 0;
	  else goto L;
  }
  return 0;
}