/*
   * misc.c
   *
   * PURPOSE
   *	Miscellaneous 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 Dave Boynton
   *  (C) 1998-2004 Ben Fennema
   *  (C) 1999-2000 Stelias Computing Inc
   *
   * HISTORY
   *
   *  04/19/99 blf  partial support for reading/writing specific EA's
   */
  
  #include "udfdecl.h"
  
  #include <linux/fs.h>
  #include <linux/string.h>

  #include <linux/crc-itu-t.h>

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

  struct buffer_head *udf_tgetblk(struct super_block *sb, udf_pblk_t block)

  {
  	if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
  		return sb_getblk(sb, udf_fixed_to_variable(block));
  	else
  		return sb_getblk(sb, block);
  }

  struct buffer_head *udf_tread(struct super_block *sb, udf_pblk_t block)

  {
  	if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
  		return sb_bread(sb, udf_fixed_to_variable(block));
  	else
  		return sb_bread(sb, block);
  }

  struct genericFormat *udf_add_extendedattr(struct inode *inode, uint32_t size,
  					   uint32_t type, uint8_t loc)

  {
  	uint8_t *ea = NULL, *ad = NULL;
  	int offset;
  	uint16_t crclen;

  	struct udf_inode_info *iinfo = UDF_I(inode);

  	ea = iinfo->i_data;

  	if (iinfo->i_lenEAttr) {

  		ad = iinfo->i_data + iinfo->i_lenEAttr;

  	} else {

  		ad = ea;
  		size += sizeof(struct extendedAttrHeaderDesc);
  	}
  
  	offset = inode->i_sb->s_blocksize - udf_file_entry_alloc_offset(inode) -

  		iinfo->i_lenAlloc;

  
  	/* TODO - Check for FreeEASpace */

  	if (loc & 0x01 && offset >= size) {

  		struct extendedAttrHeaderDesc *eahd;
  		eahd = (struct extendedAttrHeaderDesc *)ea;

  		if (iinfo->i_lenAlloc)
  			memmove(&ad[size], ad, iinfo->i_lenAlloc);

  		if (iinfo->i_lenEAttr) {

  			/* check checksum/crc */

  			if (eahd->descTag.tagIdent !=
  					cpu_to_le16(TAG_IDENT_EAHD) ||

  			    le32_to_cpu(eahd->descTag.tagLocation) !=

  					iinfo->i_location.logicalBlockNum)

  				return NULL;

  		} else {

  			struct udf_sb_info *sbi = UDF_SB(inode->i_sb);

  			size -= sizeof(struct extendedAttrHeaderDesc);

  			iinfo->i_lenEAttr +=

  				sizeof(struct extendedAttrHeaderDesc);

  			eahd->descTag.tagIdent = cpu_to_le16(TAG_IDENT_EAHD);

  			if (sbi->s_udfrev >= 0x0200)

  				eahd->descTag.descVersion = cpu_to_le16(3);
  			else
  				eahd->descTag.descVersion = cpu_to_le16(2);

  			eahd->descTag.tagSerialNum =
  					cpu_to_le16(sbi->s_serial_number);
  			eahd->descTag.tagLocation = cpu_to_le32(

  					iinfo->i_location.logicalBlockNum);

  			eahd->impAttrLocation = cpu_to_le32(0xFFFFFFFF);
  			eahd->appAttrLocation = cpu_to_le32(0xFFFFFFFF);
  		}

  		offset = iinfo->i_lenEAttr;

  		if (type < 2048) {

  			if (le32_to_cpu(eahd->appAttrLocation) <

  					iinfo->i_lenEAttr) {

  				uint32_t aal =
  					le32_to_cpu(eahd->appAttrLocation);

  				memmove(&ea[offset - aal + size],
  					&ea[aal], offset - aal);

  				offset -= aal;

  				eahd->appAttrLocation =
  						cpu_to_le32(aal + size);

  			}

  			if (le32_to_cpu(eahd->impAttrLocation) <

  					iinfo->i_lenEAttr) {

  				uint32_t ial =
  					le32_to_cpu(eahd->impAttrLocation);

  				memmove(&ea[offset - ial + size],
  					&ea[ial], offset - ial);

  				offset -= ial;

  				eahd->impAttrLocation =
  						cpu_to_le32(ial + size);

  			}

  		} else if (type < 65536) {

  			if (le32_to_cpu(eahd->appAttrLocation) <

  					iinfo->i_lenEAttr) {

  				uint32_t aal =
  					le32_to_cpu(eahd->appAttrLocation);

  				memmove(&ea[offset - aal + size],
  					&ea[aal], offset - aal);

  				offset -= aal;

  				eahd->appAttrLocation =
  						cpu_to_le32(aal + size);

  			}
  		}
  		/* rewrite CRC + checksum of eahd */

  		crclen = sizeof(struct extendedAttrHeaderDesc) - sizeof(struct tag);

  		eahd->descTag.descCRCLength = cpu_to_le16(crclen);

  		eahd->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)eahd +

  						sizeof(struct tag), crclen));

  		eahd->descTag.tagChecksum = udf_tag_checksum(&eahd->descTag);

  		iinfo->i_lenEAttr += size;

  		return (struct genericFormat *)&ea[offset];
  	}

  	return NULL;
  }

  struct genericFormat *udf_get_extendedattr(struct inode *inode, uint32_t type,
  					   uint8_t subtype)

  {
  	struct genericFormat *gaf;
  	uint8_t *ea = NULL;
  	uint32_t offset;

  	struct udf_inode_info *iinfo = UDF_I(inode);

  	ea = iinfo->i_data;

  	if (iinfo->i_lenEAttr) {

  		struct extendedAttrHeaderDesc *eahd;
  		eahd = (struct extendedAttrHeaderDesc *)ea;
  
  		/* check checksum/crc */

  		if (eahd->descTag.tagIdent !=
  				cpu_to_le16(TAG_IDENT_EAHD) ||

  		    le32_to_cpu(eahd->descTag.tagLocation) !=

  				iinfo->i_location.logicalBlockNum)

  			return NULL;

  		if (type < 2048)
  			offset = sizeof(struct extendedAttrHeaderDesc);
  		else if (type < 65536)
  			offset = le32_to_cpu(eahd->impAttrLocation);
  		else
  			offset = le32_to_cpu(eahd->appAttrLocation);

  		while (offset < iinfo->i_lenEAttr) {

  			gaf = (struct genericFormat *)&ea[offset];

  			if (le32_to_cpu(gaf->attrType) == type &&
  					gaf->attrSubtype == subtype)

  				return gaf;
  			else
  				offset += le32_to_cpu(gaf->attrLength);
  		}
  	}

  	return NULL;
  }
  
  /*
   * udf_read_tagged
   *
   * PURPOSE
   *	Read the first block of a tagged descriptor.
   *
   * HISTORY
   *	July 1, 1997 - Andrew E. Mileski
   *	Written, tested, and released.
   */

  struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block,

  				    uint32_t location, uint16_t *ident)

  {

  	struct tag *tag_p;

  	struct buffer_head *bh = NULL;

  	u8 checksum;

  
  	/* Read the block */
  	if (block == 0xFFFFFFFF)
  		return NULL;

  	bh = udf_tread(sb, block);

  	if (!bh) {

  		udf_err(sb, "read failed, block=%u, location=%u
  ",

  			block, location);

  		return NULL;
  	}

  	tag_p = (struct tag *)(bh->b_data);

  
  	*ident = le16_to_cpu(tag_p->tagIdent);

  	if (location != le32_to_cpu(tag_p->tagLocation)) {

  		udf_debug("location mismatch block %u, tag %u != %u
  ",

  			  block, le32_to_cpu(tag_p->tagLocation), location);

  		goto error_out;
  	}

  	/* Verify the tag checksum */

  	checksum = udf_tag_checksum(tag_p);
  	if (checksum != tag_p->tagChecksum) {

  		udf_err(sb, "tag checksum failed, block %u: 0x%02x != 0x%02x
  ",
  			block, checksum, tag_p->tagChecksum);

  		goto error_out;
  	}
  
  	/* Verify the tag version */

  	if (tag_p->descVersion != cpu_to_le16(0x0002U) &&
  	    tag_p->descVersion != cpu_to_le16(0x0003U)) {

  		udf_err(sb, "tag version 0x%04x != 0x0002 || 0x0003, block %u
  ",
  			le16_to_cpu(tag_p->descVersion), block);

  		goto error_out;
  	}
  
  	/* Verify the descriptor CRC */

  	if (le16_to_cpu(tag_p->descCRCLength) + sizeof(struct tag) > sb->s_blocksize ||

  	    le16_to_cpu(tag_p->descCRC) == crc_itu_t(0,

  					bh->b_data + sizeof(struct tag),

  					le16_to_cpu(tag_p->descCRCLength)))

  		return bh;

  	udf_debug("Crc failure block %u: crc = %u, crclen = %u
  ", block,

  		  le16_to_cpu(tag_p->descCRC),
  		  le16_to_cpu(tag_p->descCRCLength));

  error_out:

  	brelse(bh);
  	return NULL;
  }

  struct buffer_head *udf_read_ptagged(struct super_block *sb,
  				     struct kernel_lb_addr *loc,

  				     uint32_t offset, uint16_t *ident)

  {
  	return udf_read_tagged(sb, udf_get_lb_pblock(sb, loc, offset),

  			       loc->logicalBlockNum + offset, ident);

  }

  void udf_update_tag(char *data, int length)
  {

  	struct tag *tptr = (struct tag *)data;
  	length -= sizeof(struct tag);

  	tptr->descCRCLength = cpu_to_le16(length);

  	tptr->descCRC = cpu_to_le16(crc_itu_t(0, data + sizeof(struct tag), length));

  	tptr->tagChecksum = udf_tag_checksum(tptr);

  }
  
  void udf_new_tag(char *data, uint16_t ident, uint16_t version, uint16_t snum,

  		 uint32_t loc, int length)

  {

  	struct tag *tptr = (struct tag *)data;

  	tptr->tagIdent = cpu_to_le16(ident);
  	tptr->descVersion = cpu_to_le16(version);
  	tptr->tagSerialNum = cpu_to_le16(snum);
  	tptr->tagLocation = cpu_to_le32(loc);
  	udf_update_tag(data, length);
  }

  u8 udf_tag_checksum(const struct tag *t)

  {
  	u8 *data = (u8 *)t;
  	u8 checksum = 0;
  	int i;

  	for (i = 0; i < sizeof(struct tag); ++i)

  		if (i != 4) /* position of checksum */
  			checksum += data[i];
  	return checksum;
  }