/*
 *  linux/lib/update.c
 *
 *  (C) 2021  Huan
 */

#include <errno.h>
#include <a.out.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <asm/segment.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <new.h>

#define	DIRBUF		8192		/* buffer size for fs-indep. dirs */
	/* must in general be larger than the filesystem buffer size */

int sys_getdents(unsigned int fd, struct linux_dirent *d, unsigned int count)
{
    struct linux_dirent tmp;
    struct file  * file;
	  struct m_inode * inode;
    struct buffer_head * block;
    struct dir_entry * ptr;
    char * buf;
	  int inum;                                                    /*the "inum"st inode.*/
    int dnum;                                                    /*the "dnum"st element of array "d".*/
    int ld_size;
    int i;
    int result;
    ld_size = sizeof(struct linux_dirent);                        /*the size of struct "linux_dirent".(24)*/
    file = current->filp[fd];                                     /*get the current file pointer we need.*/
    if (fd >= NR_OPEN) return -EINVAL;                            /*shu zu yue jie*/
	  if (count == 0) return -1;                                    /*the size of dirp is too small(0)*/
    if (!file) return ENOTDIR;                                    /*can't open file.*/
    inode = file->f_inode;                                        /*get the inode of this file.*/ 
    block = bread(inode->i_dev,inode->i_zone[0]);                 /*get the block that storing inodes.*/
    tmp.d_reclen = sizeof(tmp);                                   /*the size of struct "linux_dirent".(24)*/
    tmp.d_off = 0;                                                /*useless*/
    buf = &tmp;                                                   /*get the address of tmp.*/
    dnum = 0;                                                     /*the "pian yi liang" of array "d".*/         
                                  
    for (inum = 0;(inum*sizeof(struct dir_entry))<inode->i_size;inum++) {
        if (dnum >= (count-ld_size)) return 0;                    /*shu zu "d" yue jie*/
        ptr = (struct dir_entry *) (block->b_data + (inum*sizeof(struct dir_entry)));
        /*get the address of the next inode.*/
        if (!ptr -> inode) continue;                              /*ignore current inode if it is empty.*/
        tmp.d_ino = ptr -> inode;                                 /*copy the inode into tmp.*/
		    for (i = 0; i < 14; i++) tmp.d_name[i] = ptr -> name[i];  /*copy current file name into tmp.*/
        for (i = 0; i < tmp.d_reclen; i++){
            put_fs_byte(*(buf+i),((char*)d)+i+dnum*tmp.d_reclen); /*copy tmp to array "d"(from kernal to user).*/
        }
        dnum++;                                                   /*fill the next element of array "d".*/  
    }
    result = dnum*tmp.d_reclen;                                    /*lenth of the array "d"*/
    return result;
}

int sys_pipe2(int* fd, int flags){
	if(flags == 0){
	struct m_inode * inode;
	struct file * f[2];
	int fp[2];
	int i,j;

	j=0;
	for(i=0;j<2 && i<NR_FILE;i++)
		if (!file_table[i].f_count)
			(f[j++]=i+file_table)->f_count++;
	if (j==1)
		f[0]->f_count=0;
	if (j<2)
		return -1;
	j=0;
	for(i=0;j<2 && i<NR_OPEN;i++)
		if (!current->filp[i]) {
			current->filp[ fp[j]=i ] = f[j];
			j++;
		}
	if (j==1)
		current->filp[fp[0]]=NULL;
	if (j<2) {
		f[0]->f_count=f[1]->f_count=0;
		return -1;
	}
	if (!(inode=get_pipe_inode())) {
		current->filp[fp[0]] =
			current->filp[fp[1]] = NULL;
		f[0]->f_count = f[1]->f_count = 0;
		return -1;
	}
	f[0]->f_inode = f[1]->f_inode = inode;
	f[0]->f_pos = f[1]->f_pos = 0;
	f[0]->f_mode = 1;		/* read */
	f[1]->f_mode = 2;		/* write */
	put_fs_long(fp[0],0+fd);
	put_fs_long(fp[1],1+fd);
	return 0;
	} 
}


int sys_sleep(unsigned int seconds){
  sys_signal(SIGALRM,SIG_IGN,NULL);
  sys_alarm(seconds);
  pause();
	return 0;
}