/*
 * directory.c
 *
 * PURPOSE
 *	Directory related functions
 *
 * 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.
 */

#include "udfdecl.h"
#include "udf_i.h"

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/bio.h>

struct fileIdentDesc *udf_fileident_read(struct inode *dir, loff_t *nf_pos,
					 struct udf_fileident_bh *fibh,
					 struct fileIdentDesc *cfi,
					 struct extent_position *epos,
					 struct kernel_lb_addr *eloc, uint32_t *elen,
					 sector_t *offset)
{
	struct fileIdentDesc *fi;
	int i, num;
	udf_pblk_t block;
	struct buffer_head *tmp, *bha[16];
	struct udf_inode_info *iinfo = UDF_I(dir);

	fibh->soffset = fibh->eoffset;

	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
		fi = udf_get_fileident(iinfo->i_data -
				       (iinfo->i_efe ?
					sizeof(struct extendedFileEntry) :
					sizeof(struct fileEntry)),
				       dir->i_sb->s_blocksize,
				       &(fibh->eoffset));
		if (!fi)
			return NULL;

		*nf_pos += fibh->eoffset - fibh->soffset;

		memcpy((uint8_t *)cfi, (uint8_t *)fi,
		       sizeof(struct fileIdentDesc));

		return fi;
	}

	if (fibh->eoffset == dir->i_sb->s_blocksize) {
		uint32_t lextoffset = epos->offset;
		unsigned char blocksize_bits = dir->i_sb->s_blocksize_bits;

		if (udf_next_aext(dir, epos, eloc, elen, 1) !=
		    (EXT_RECORDED_ALLOCATED >> 30))
			return NULL;

		block = udf_get_lb_pblock(dir->i_sb, eloc, *offset);

		(*offset)++;

		if ((*offset << blocksize_bits) >= *elen)
			*offset = 0;
		else
			epos->offset = lextoffset;

		brelse(fibh->sbh);
		fibh->sbh = fibh->ebh = udf_tread(dir->i_sb, block);
		if (!fibh->sbh)
			return NULL;
		fibh->soffset = fibh->eoffset = 0;

		if (!(*offset & ((16 >> (blocksize_bits - 9)) - 1))) {
			i = 16 >> (blocksize_bits - 9);
			if (i + *offset > (*elen >> blocksize_bits))
				i = (*elen >> blocksize_bits)-*offset;
			for (num = 0; i > 0; i--) {
				block = udf_get_lb_pblock(dir->i_sb, eloc,
							  *offset + i);
				tmp = udf_tgetblk(dir->i_sb, block);
				if (tmp && !buffer_uptodate(tmp) &&
						!buffer_locked(tmp))
					bha[num++] = tmp;
				else
					brelse(tmp);
			}
			if (num) {
				bh_readahead_batch(num, bha, REQ_RAHEAD);
				for (i = 0; i < num; i++)
					brelse(bha[i]);
			}
		}
	} else if (fibh->sbh != fibh->ebh) {
		brelse(fibh->sbh);
		fibh->sbh = fibh->ebh;
	}

	fi = udf_get_fileident(fibh->sbh->b_data, dir->i_sb->s_blocksize,
			       &(fibh->eoffset));

	if (!fi)
		return NULL;

	*nf_pos += fibh->eoffset - fibh->soffset;

	if (fibh->eoffset <= dir->i_sb->s_blocksize) {
		memcpy((uint8_t *)cfi, (uint8_t *)fi,
		       sizeof(struct fileIdentDesc));
	} else if (fibh->eoffset > dir->i_sb->s_blocksize) {
		uint32_t lextoffset = epos->offset;

		if (udf_next_aext(dir, epos, eloc, elen, 1) !=
		    (EXT_RECORDED_ALLOCATED >> 30))
			return NULL;

		block = udf_get_lb_pblock(dir->i_sb, eloc, *offset);

		(*offset)++;

		if ((*offset << dir->i_sb->s_blocksize_bits) >= *elen)
			*offset = 0;
		else
			epos->offset = lextoffset;

		fibh->soffset -= dir->i_sb->s_blocksize;
		fibh->eoffset -= dir->i_sb->s_blocksize;

		fibh->ebh = udf_tread(dir->i_sb, block);
		if (!fibh->ebh)
			return NULL;

		if (sizeof(struct fileIdentDesc) > -fibh->soffset) {
			int fi_len;

			memcpy((uint8_t *)cfi, (uint8_t *)fi, -fibh->soffset);
			memcpy((uint8_t *)cfi - fibh->soffset,
			       fibh->ebh->b_data,
			       sizeof(struct fileIdentDesc) + fibh->soffset);

			fi_len = udf_dir_entry_len(cfi);
			*nf_pos += fi_len - (fibh->eoffset - fibh->soffset);
			fibh->eoffset = fibh->soffset + fi_len;
		} else {
			memcpy((uint8_t *)cfi, (uint8_t *)fi,
			       sizeof(struct fileIdentDesc));
		}
	}
	/* Got last entry outside of dir size - fs is corrupted! */
	if (*nf_pos > dir->i_size)
		return NULL;
	return fi;
}

struct fileIdentDesc *udf_get_fileident(void *buffer, int bufsize, int *offset)
{
	struct fileIdentDesc *fi;
	int lengthThisIdent;
	uint8_t *ptr;
	int padlen;

	if ((!buffer) || (!offset)) {
		udf_debug("invalidparms, buffer=%p, offset=%p\n",
			  buffer, offset);
		return NULL;
	}

	ptr = buffer;

	if ((*offset > 0) && (*offset < bufsize))
		ptr += *offset;
	fi = (struct fileIdentDesc *)ptr;
	if (fi->descTag.tagIdent != cpu_to_le16(TAG_IDENT_FID)) {
		udf_debug("0x%x != TAG_IDENT_FID\n",
			  le16_to_cpu(fi->descTag.tagIdent));
		udf_debug("offset: %d sizeof: %lu bufsize: %d\n",
			  *offset, (unsigned long)sizeof(struct fileIdentDesc),
			  bufsize);
		return NULL;
	}
	if ((*offset + sizeof(struct fileIdentDesc)) > bufsize)
		lengthThisIdent = sizeof(struct fileIdentDesc);
	else
		lengthThisIdent = sizeof(struct fileIdentDesc) +
			fi->lengthFileIdent + le16_to_cpu(fi->lengthOfImpUse);

	/* we need to figure padding, too! */
	padlen = lengthThisIdent % UDF_NAME_PAD;
	if (padlen)
		lengthThisIdent += (UDF_NAME_PAD - padlen);
	*offset = *offset + lengthThisIdent;

	return fi;
}

struct short_ad *udf_get_fileshortad(uint8_t *ptr, int maxoffset, uint32_t *offset,
			      int inc)
{
	struct short_ad *sa;

	if ((!ptr) || (!offset)) {
		pr_err("%s: invalidparms\n", __func__);
		return NULL;
	}

	if ((*offset + sizeof(struct short_ad)) > maxoffset)
		return NULL;
	else {
		sa = (struct short_ad *)ptr;
		if (sa->extLength == 0)
			return NULL;
	}

	if (inc)
		*offset += sizeof(struct short_ad);
	return sa;
}

struct long_ad *udf_get_filelongad(uint8_t *ptr, int maxoffset, uint32_t *offset, int inc)
{
	struct long_ad *la;

	if ((!ptr) || (!offset)) {
		pr_err("%s: invalidparms\n", __func__);
		return NULL;
	}

	if ((*offset + sizeof(struct long_ad)) > maxoffset)
		return NULL;
	else {
		la = (struct long_ad *)ptr;
		if (la->extLength == 0)
			return NULL;
	}

	if (inc)
		*offset += sizeof(struct long_ad);
	return la;
}
