fork.c

模拟操作系统底层通过管道的文件传送,定义读写缓冲区,编译后,可看到结果

#include "sys/types.h"
#include "sys/file.h"
#include "unistd.h"

char r_buff[4];
char w_buff[4];

int pipe_fd[2];
pid_t pid1,pid2,pid3,pid4;

int producer(int id);
int consumer(int id);

int main(int argc,char **argv)
{
if(pipe(pipe_fd)<0)
 {printf("pipe create error.\n");
  exit(-1);
 }
else
 {
  printf("pipe is created successfully!\n");
  
  pid1=fork();
  if(pid1==0)
    {printf("pid1=%d in parent process.\n",pid1);producer(1); }
  else
    printf("pid1=%d\n",pid1); 
  
  pid2=fork();
  if(pid2==0)
    producer(2);
  else
    printf("pid2=%d\n",pid2); 
  
  pid3=fork();
  if(pid3==0)
    consumer(1);
  else
    printf("pid3=%d\n",pid3); 
  
  pid4=fork();
  if(pid4==0)
    consumer(2);
  else
    printf("pid4=%d\n",pid4); 
 }

int i,pid,status;
for(i=0;i<4;i++)
  pid=wait(&status);

close(pipe_fd[1]);
close(pipe_fd[0]);
printf("---The program is over!---\n");
exit(0);
}
int producer(int id)
{
printf("producer %d is running!\n",id);
int i;
for(i=1;i<10;i++)
  {
   sleep(3);
   if(id==1)
     sprintf(w_buff,"a%02d",i);
   else
     sprintf(w_buff,"b%02d",i);
   if(write(pipe_fd[1],w_buff,4)==-1)
     printf("write to pipe error.\n");  
  }
write(pipe_fd[1],"end\0",4);
printf("producer %d is over!\n",id);
exit(id);
}
int consumer(int id)
{
while(1)
 {
  sleep(2);
  read(pipe_fd[0],r_buff,4);
  if(strcmp(r_buff,"end")==0)break;
  printf("consumer %d get %s\n",id,r_buff);
 }
printf("consumer %d is over!\n",id);
exit(id);
}