/*
   * dir.c
   *
   * PURPOSE
   *  Directory handling routines for the OSTA-UDF(tm) filesystem.
   *

   * COPYRIGHT
   *	This file is distributed under the terms of the GNU General Public
   *	License (GPL). Copies of the GPL can be obtained from:
   *		ftp://prep.ai.mit.edu/pub/gnu/GPL
   *	Each contributing author retains all rights to their own work.
   *
   *  (C) 1998-2004 Ben Fennema
   *
   * HISTORY
   *
   *  10/05/98 dgb  Split directory operations into its own file
   *                Implemented directory reads via do_udf_readdir
   *  10/06/98      Made directory operations work!
   *  11/17/98      Rewrote directory to support ICBTAG_FLAG_AD_LONG
   *  11/25/98 blf  Rewrote directory handling (readdir+lookup) to support reading
   *                across blocks.
   *  12/12/98      Split out the lookup code to namei.c. bulk of directory
   *                code now in directory.c:udf_fileident_read.
   */
  
  #include "udfdecl.h"
  
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/mm.h>
  #include <linux/slab.h>

  
  #include "udf_i.h"
  #include "udf_sb.h"

  
  static int udf_readdir(struct file *file, struct dir_context *ctx)

  {

  	struct inode *dir = file_inode(file);
  	struct udf_inode_info *iinfo = UDF_I(dir);

  	struct udf_fileident_bh fibh = { .sbh = NULL, .ebh = NULL};

  	struct fileIdentDesc *fi = NULL;

  	struct fileIdentDesc cfi;
  	int block, iblock;

  	loff_t nf_pos;

  	int flen;

  	unsigned char *fname = NULL;
  	unsigned char *nameptr;

  	uint16_t liu;
  	uint8_t lfi;

  	loff_t size = udf_ext0_offset(dir) + dir->i_size;

  	struct buffer_head *tmp, *bha[16];

  	struct kernel_lb_addr eloc;

  	uint32_t elen;

  	sector_t offset;

  	int i, num, ret = 0;

  	struct extent_position epos = { NULL, 0, {0, 0} };

  	struct super_block *sb = dir->i_sb;

  	if (ctx->pos == 0) {
  		if (!dir_emit_dot(file, ctx))
  			return 0;
  		ctx->pos = 1;
  	}
  	nf_pos = (ctx->pos - 1) << 2;

  	if (nf_pos >= size)

  		goto out;
  
  	fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
  	if (!fname) {
  		ret = -ENOMEM;
  		goto out;
  	}

  
  	if (nf_pos == 0)

  		nf_pos = udf_ext0_offset(dir);

  	fibh.soffset = fibh.eoffset = nf_pos & (sb->s_blocksize - 1);

  	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {

  		if (inode_bmap(dir, nf_pos >> sb->s_blocksize_bits,

  		    &epos, &eloc, &elen, &offset)
  		    != (EXT_RECORDED_ALLOCATED >> 30)) {
  			ret = -ENOENT;
  			goto out;
  		}

  		block = udf_get_lb_pblock(sb, &eloc, offset);
  		if ((++offset << sb->s_blocksize_bits) < elen) {

  			if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)

  				epos.offset -= sizeof(struct short_ad);

  			else if (iinfo->i_alloc_type ==

  					ICBTAG_FLAG_AD_LONG)

  				epos.offset -= sizeof(struct long_ad);

  		} else {

  			offset = 0;

  		}

  		if (!(fibh.sbh = fibh.ebh = udf_tread(sb, block))) {

  			ret = -EIO;
  			goto out;

  		}

  		if (!(offset & ((16 >> (sb->s_blocksize_bits - 9)) - 1))) {
  			i = 16 >> (sb->s_blocksize_bits - 9);
  			if (i + offset > (elen >> sb->s_blocksize_bits))
  				i = (elen >> sb->s_blocksize_bits) - offset;

  			for (num = 0; i > 0; i--) {

  				block = udf_get_lb_pblock(sb, &eloc, offset + i);
  				tmp = udf_tgetblk(sb, block);

  				if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))

  					bha[num++] = tmp;
  				else
  					brelse(tmp);
  			}

  			if (num) {

  				ll_rw_block(READA, num, bha);

  				for (i = 0; i < num; i++)

  					brelse(bha[i]);
  			}
  		}

  	}

  	while (nf_pos < size) {

  		struct kernel_lb_addr tloc;
  
  		ctx->pos = (nf_pos >> 2) + 1;

  		fi = udf_fileident_read(dir, &nf_pos, &fibh, &cfi, &epos, &eloc,
  					&elen, &offset);

  		if (!fi)
  			goto out;

  
  		liu = le16_to_cpu(cfi.lengthOfImpUse);
  		lfi = cfi.lengthFileIdent;

  		if (fibh.sbh == fibh.ebh) {

  			nameptr = fi->fileIdent + liu;

  		} else {

  			int poffset;	/* Unpaded ending offset */

  			poffset = fibh.soffset + sizeof(struct fileIdentDesc) + liu + lfi;

  			if (poffset >= lfi) {
  				nameptr = (char *)(fibh.ebh->b_data + poffset - lfi);
  			} else {

  				nameptr = fname;

  				memcpy(nameptr, fi->fileIdent + liu,
  				       lfi - poffset);
  				memcpy(nameptr + lfi - poffset,
  				       fibh.ebh->b_data, poffset);

  			}
  		}

  		if ((cfi.fileCharacteristics & FID_FILE_CHAR_DELETED) != 0) {

  			if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))

  				continue;
  		}

  
  		if ((cfi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) != 0) {

  			if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))

  				continue;
  		}

  		if (cfi.fileCharacteristics & FID_FILE_CHAR_PARENT) {

  			if (!dir_emit_dotdot(file, ctx))
  				goto out;
  			continue;

  		}

  		flen = udf_get_filename(sb, nameptr, lfi, fname, UDF_NAME_LEN);

  		if (flen < 0)

  			continue;
  
  		tloc = lelb_to_cpu(cfi.icb.extLocation);

  		iblock = udf_get_lb_pblock(sb, &tloc, 0);

  		if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))

  			goto out;

  	} /* end while */

  	ctx->pos = (nf_pos >> 2) + 1;

  out:

  	if (fibh.sbh != fibh.ebh)

  		brelse(fibh.ebh);
  	brelse(fibh.sbh);
  	brelse(epos.bh);

  	kfree(fname);

  	return ret;

  }

  /* readdir and lookup functions */
  const struct file_operations udf_dir_operations = {

  	.llseek			= generic_file_llseek,

  	.read			= generic_read_dir,

  	.iterate		= udf_readdir,

  	.unlocked_ioctl		= udf_ioctl,

  	.fsync			= generic_file_fsync,

  };