#include<errno.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/stat.h>
#include<sys/sysmacros.h>
#include<unistd.h>
/*
*    As for the fifo we can creat it use both
*    mkfifo(const char *pathname,mode_t mode);
*   and
*   mknod(); to realize it
*/



void usage(void)
{
    fprintf(stderr,"usage: mknod <path> [b|c|u|p]\n ","<major> <minor>\n");
    exit(1);
}

int main(int argc,const char **argv)
{
    int major=0,minor=0;
    const char *path;
    int mode=0666;
    char *end;
    int args;
    
    if(argc<3)
        usage();
    
    path=argv[1];
    if(!strcmp(argv[2],"b"))
    {
        mode|=S_IFBLK;
        args=5;
    }
    else if(!strcmp(argv[2],"p"))
    {
        mode|=S_IFIFO;                /*************if this file is a named pipe********/
        args=3;
    }
    else
    {
        fprintf(stderr,"unknown node type %s\n",argv[2]);
        return 1;
    }
    if(args==5)
    {
        major=strtol(argv[3],&end,0);
        if(*end)
        {
            fprintf(stderr,"bad major number %s\n",argv[3]);
            return 1;
        }
        
        minor=strtol(argv[4],&end,0);
        if(*end)
        {
            fprintf(stderr,"bad minor number %s\n",argv[4]);
            return 1;
        }
    }
    
    if(mknod(path,mode,makedev(major,minor)))
    {
        fprintf(stderr,"mknod failed: %s \n",strerror(errno));
        return 1;
    }
    
    return 0;
}
/*程序2.命名管道的测试通过上面的程序我们已经建立了一个tes 的有名管道*/
#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
int main(void)
{
    int fd;
    char buf[100];
    fd=open("/home/program/mknod/tes",O_RDWR);
    if(fd<0)
    {
        perror("Open");
        exit(1);
    }
    if(write(fd,"Hello world!\n",13)!=13)
    {
        perror("write");
        exit(1);
    }

    if(read(fd,buf,13)!=13)
    {
        perror("read");
        exit(1);
    }
    printf("%s",buf);
    return 0;
}