多进程实现拷贝

#include <myhead.h>
//定义结构体
typedef struct INFO
{
    const char *src_file;
    const char *dest_file;
    int mv;
    int size;

}info_t;

//获取源文件的大小并且创建目标文件
int size_creat(const char *src_file,const char *dest_file)
{
    //获取源文件的大小（字节）
    int src_fd = open(src_file,O_RDONLY);

    if(-1 == src_fd)
    {
        perror("open error");
        return -1;
    }

    int size = lseek(src_fd,0,SEEK_END);

    close(src_fd);

    //创建目标文件

    int dest_fd = open(dest_file,O_WRONLY | O_CREAT | O_TRUNC,0666);

    if(-1 == dest_fd)
    {
        perror("open error");
        return -1;
    }

    close(dest_fd);

    return size;
}

//复制源文件内容到目标文件内容中
void *cp(void *arg)
{
    //强制类型转换
    info_t info = *(info_t *)arg;

    int src_fd = 0;

    int dest_fd = 0;

    //打开源文件
    if(-1 == (src_fd = open(info.src_file,O_RDONLY)))
    {
        perror("open error");
        pthread_exit(NULL);
    }
    //打开目标文件
    if(-1 == (dest_fd = open(info.dest_file,O_WRONLY)))
    {
        perror("open error");
        pthread_exit(NULL);
    }

    //定位光标
    lseek(src_fd,info.mv,SEEK_SET);

    lseek(dest_fd,info.mv,SEEK_SET);

    int ret = 0;
    int num = 0;
    char buf[64] = {0};

    while (1)
    {
        ret = read(src_fd,buf,sizeof(buf));

        if(0 == ret)
        {
            break;
        }

        num += ret;

        if(num > info.size)
        {
            write(dest_fd,buf,info.size - (num - ret));
            break;
        }

        write(dest_fd,buf,ret);
       
    }
    //关闭文件
    close(src_fd);

    close(dest_fd);

}

int main(int argc, char const *argv[])
{
    if(3 != argc)
    {
        printf("Usage : %s src_file dest_file\n",argv[0]);
        return -1;
    }

    int size = 0;

    size = size_creat(argv[1],argv[2]);

    //线程1复制文件内容的前一半
    //线程2复制文件内容的后一半
    info_t arg[2] = {

        {argv[1],argv[2],0,size/2},

        {argv[1],argv[2],size/2,size - size/2}

    };

    pthread_t thread1 = 0;

    pthread_t thread2 = 0;

    int ret = 0;

    //创建线程1
    if(0 != (ret = pthread_create(&thread1,NULL,cp,&arg[0])))
    {
        printf("pthread_create error : errno = [%d] errstr = [%s]\n",ret,strerror(ret));
        exit(EXIT_FAILURE);
    }
    //创建线程2
    if(0 != (ret = pthread_create(&thread2,NULL,cp,&arg[1])))
    {
        printf("pthread_create error : errno = [%d] errstr = [%s]\n",ret,strerror(ret));
        exit(EXIT_FAILURE);
    }

    pthread_join(thread1,NULL);
    pthread_join(thread2,NULL);
    return 0;
}

 

使用多线程完成两个文件的拷贝，第一个线程拷贝前一半，第二个线程拷贝后一半，主线程关闭