#include <stdio.h>#include <sys/stat.h>#include <fcntl.h>#include <stdlib.h>#include <sys/types.h>#include <unistd.h>#define BUFFER_SIZE 1024#define SRC_FILE "src_file"#define DEST_FILE "dest_file"#define OFFSET 10240#define errlog(errmsg) perror(errmsg);\ printf("--%s--%s--%d--\n",\ __FILE__, __FUNCTION__, __LINE__);\ return -1;int main(int argc, const char *argv[]){ int fds, fdd; unsigned char buf[BUFFER_SIZE]; ssize_t read_led; if((fds = open(SRC_FILE, O_RDONLY)) < 0){ errlog("open error"); } if((fdd = open(DEST_FILE, O_WRONLY|O_CREAT|O_TRUNC, 0664)) < 0){ errlog("open error"); } lseek(fds, -OFFSET, SEEK_END); while((read_led = read(fds, buf, sizeof(buf))) > 0){ write(fdd, buf, read_led); } close(fds); close(fdd); return 0;}各位哥哥姐姐，这是文件复制的代码，我看不懂，能解释一下吗？