/*
    实现cp命令：
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

int main(int argc, char *argv[])
{
    int rd_fd, wr_fd;//读文件描述符 和 写文件描述符
    char buf[128]={0};
    int rd_ret = 0;    

    if(argc < 3)
    {
        printf("please input src file and des file!\n");
        return -1;
    }
    //打开源文件
    rd_fd = open(argv[1], O_RDONLY);
    if(rd_fd < 0)
    {
        printf("open src file %s failed!\n", argv[1]);
        return -2;
    }
    printf("open src file %s succ, rd_fd = %d\n", argv[1], rd_fd);

    //打开目标文件
    wr_fd = open(argv[2], O_WRONLY|O_CREAT);
    if(wr_fd < 0)
    {
        printf("open des file %s failed!\n", argv[2]);
        return -3;
    }    
    while(1)
    {    
        rd_ret = read(rd_fd, buf, 128);
        if(rd_ret < 128)//判断数据是否读取完毕
        {
            break;
        }
        write(wr_fd, buf, rd_ret);
        memset(buf, 0, 128);//清理缓存
    }
    write(wr_fd, buf, rd_ret);//做最后一次写入
    
    //关闭文件描述符
    close(wr_fd);
    close(rd_fd)
    return 0;
}