/*
   *  linux/fs/isofs/rock.c
   *
   *  (C) 1992, 1993  Eric Youngdale
   *
   *  Rock Ridge Extensions to iso9660
   */

  #include <linux/slab.h>
  #include <linux/pagemap.h>

  #include "isofs.h"

  #include "rock.h"

  /*
   * These functions are designed to read the system areas of a directory record

   * and extract relevant information.  There are different functions provided
   * depending upon what information we need at the time.  One function fills
   * out an inode structure, a second one extracts a filename, a third one
   * returns a symbolic link name, and a fourth one returns the extent number

   * for the file.
   */

  #define SIG(A,B) ((A) | ((B) << 8))	/* isonum_721() */

  struct rock_state {
  	void *buffer;
  	unsigned char *chr;
  	int len;
  	int cont_size;
  	int cont_extent;
  	int cont_offset;
  	struct inode *inode;
  };

  /*
   * This is a way of ensuring that we have something in the system

   * use fields that is compatible with Rock Ridge.  Return zero on success.

   */
  
  static int check_sp(struct rock_ridge *rr, struct inode *inode)
  {
  	if (rr->u.SP.magic[0] != 0xbe)
  		return -1;
  	if (rr->u.SP.magic[1] != 0xef)
  		return -1;
  	ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  	return 0;
  }

  static void setup_rock_ridge(struct iso_directory_record *de,

  			struct inode *inode, struct rock_state *rs)

  {

  	rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
  	if (rs->len & 1)
  		(rs->len)++;
  	rs->chr = (unsigned char *)de + rs->len;
  	rs->len = *((unsigned char *)de) - rs->len;
  	if (rs->len < 0)
  		rs->len = 0;

  
  	if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {

  		rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
  		rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
  		if (rs->len < 0)
  			rs->len = 0;

  	}

  }

  static void init_rock_state(struct rock_state *rs, struct inode *inode)
  {
  	memset(rs, 0, sizeof(*rs));
  	rs->inode = inode;
  }
  
  /*
   * Returns 0 if the caller should continue scanning, 1 if the scan must end
   * and -ve on error.
   */
  static int rock_continue(struct rock_state *rs)
  {
  	int ret = 1;

  	int blocksize = 1 << rs->inode->i_blkbits;
  	const int min_de_size = offsetof(struct rock_ridge, u);

  
  	kfree(rs->buffer);
  	rs->buffer = NULL;

  
  	if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
  	    (unsigned)rs->cont_size > blocksize ||
  	    (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
  		printk(KERN_NOTICE "rock: corrupted directory entry. "
  			"extent=%d, offset=%d, size=%d
  ",
  			rs->cont_extent, rs->cont_offset, rs->cont_size);
  		ret = -EIO;
  		goto out;
  	}

  	if (rs->cont_extent) {
  		struct buffer_head *bh;
  
  		rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
  		if (!rs->buffer) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		ret = -EIO;
  		bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
  		if (bh) {
  			memcpy(rs->buffer, bh->b_data + rs->cont_offset,
  					rs->cont_size);
  			put_bh(bh);
  			rs->chr = rs->buffer;
  			rs->len = rs->cont_size;
  			rs->cont_extent = 0;
  			rs->cont_size = 0;
  			rs->cont_offset = 0;
  			return 0;
  		}
  		printk("Unable to read rock-ridge attributes
  ");
  	}
  out:
  	kfree(rs->buffer);
  	rs->buffer = NULL;
  	return ret;
  }

  /*

   * We think there's a record of type `sig' at rs->chr.  Parse the signature
   * and make sure that there's really room for a record of that type.
   */
  static int rock_check_overflow(struct rock_state *rs, int sig)
  {
  	int len;
  
  	switch (sig) {
  	case SIG('S', 'P'):
  		len = sizeof(struct SU_SP_s);
  		break;
  	case SIG('C', 'E'):
  		len = sizeof(struct SU_CE_s);
  		break;
  	case SIG('E', 'R'):
  		len = sizeof(struct SU_ER_s);
  		break;
  	case SIG('R', 'R'):
  		len = sizeof(struct RR_RR_s);
  		break;
  	case SIG('P', 'X'):
  		len = sizeof(struct RR_PX_s);
  		break;
  	case SIG('P', 'N'):
  		len = sizeof(struct RR_PN_s);
  		break;
  	case SIG('S', 'L'):
  		len = sizeof(struct RR_SL_s);
  		break;
  	case SIG('N', 'M'):
  		len = sizeof(struct RR_NM_s);
  		break;
  	case SIG('C', 'L'):
  		len = sizeof(struct RR_CL_s);
  		break;
  	case SIG('P', 'L'):
  		len = sizeof(struct RR_PL_s);
  		break;
  	case SIG('T', 'F'):
  		len = sizeof(struct RR_TF_s);
  		break;
  	case SIG('Z', 'F'):
  		len = sizeof(struct RR_ZF_s);
  		break;
  	default:
  		len = 0;
  		break;
  	}
  	len += offsetof(struct rock_ridge, u);
  	if (len > rs->len) {
  		printk(KERN_NOTICE "rock: directory entry would overflow "
  				"storage
  ");
  		printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d
  ",
  				sig, len, rs->len);
  		return -EIO;
  	}
  	return 0;
  }
  
  /*

   * return length of name field; 0: not found, -1: to be ignored
   */

  int get_rock_ridge_filename(struct iso_directory_record *de,
  			    char *retname, struct inode *inode)

  {

  	struct rock_state rs;

  	struct rock_ridge *rr;
  	int sig;
  	int retnamlen = 0;
  	int truncate = 0;

  	int ret = 0;

  	if (!ISOFS_SB(inode->i_sb)->s_rock)
  		return 0;
  	*retname = 0;

  	init_rock_state(&rs, inode);
  	setup_rock_ridge(de, inode, &rs);

  repeat:

  	while (rs.len > 2) { /* There may be one byte for padding somewhere */
  		rr = (struct rock_ridge *)rs.chr;

  		/*
  		 * Ignore rock ridge info if rr->len is out of range, but
  		 * don't return -EIO because that would make the file
  		 * invisible.
  		 */

  		if (rr->len < 3)
  			goto out;	/* Something got screwed up here */

  		sig = isonum_721(rs.chr);

  		if (rock_check_overflow(&rs, sig))
  			goto eio;

  		rs.chr += rr->len;
  		rs.len -= rr->len;

  		/*
  		 * As above, just ignore the rock ridge info if rr->len
  		 * is bogus.
  		 */

  		if (rs.len < 0)

  			goto out;	/* Something got screwed up here */

  
  		switch (sig) {
  		case SIG('R', 'R'):
  			if ((rr->u.RR.flags[0] & RR_NM) == 0)
  				goto out;
  			break;
  		case SIG('S', 'P'):

  			if (check_sp(rr, inode))
  				goto out;

  			break;
  		case SIG('C', 'E'):

  			rs.cont_extent = isonum_733(rr->u.CE.extent);
  			rs.cont_offset = isonum_733(rr->u.CE.offset);
  			rs.cont_size = isonum_733(rr->u.CE.size);

  			break;
  		case SIG('N', 'M'):
  			if (truncate)

  				break;

  			if (rr->len < 5)

  				break;

  			/*
  			 * If the flags are 2 or 4, this indicates '.' or '..'.
  			 * We don't want to do anything with this, because it
  			 * screws up the code that calls us.  We don't really
  			 * care anyways, since we can just use the non-RR
  			 * name.
  			 */
  			if (rr->u.NM.flags & 6)

  				break;

  			if (rr->u.NM.flags & ~1) {
  				printk("Unsupported NM flag settings (%d)
  ",
  					rr->u.NM.flags);

  				break;

  			}
  			if ((strlen(retname) + rr->len - 5) >= 254) {
  				truncate = 1;

  				break;
  			}

  			strncat(retname, rr->u.NM.name, rr->len - 5);
  			retnamlen += rr->len - 5;
  			break;
  		case SIG('R', 'E'):

  			kfree(rs.buffer);

  			return -1;
  		default:
  			break;

  		}

  	}

  	ret = rock_continue(&rs);
  	if (ret == 0)
  		goto repeat;
  	if (ret == 1)
  		return retnamlen; /* If 0, this file did not have a NM field */

  out:

  	kfree(rs.buffer);
  	return ret;

  eio:
  	ret = -EIO;
  	goto out;

  }
  
  static int
  parse_rock_ridge_inode_internal(struct iso_directory_record *de,
  				struct inode *inode, int regard_xa)
  {

  	int symlink_len = 0;

  	int cnt, sig;
  	struct inode *reloc;
  	struct rock_ridge *rr;
  	int rootflag;

  	struct rock_state rs;
  	int ret = 0;

  
  	if (!ISOFS_SB(inode->i_sb)->s_rock)
  		return 0;

  	init_rock_state(&rs, inode);
  	setup_rock_ridge(de, inode, &rs);

  	if (regard_xa) {

  		rs.chr += 14;
  		rs.len -= 14;
  		if (rs.len < 0)
  			rs.len = 0;

  	}

  repeat:

  	while (rs.len > 2) { /* There may be one byte for padding somewhere */
  		rr = (struct rock_ridge *)rs.chr;

  		/*
  		 * Ignore rock ridge info if rr->len is out of range, but
  		 * don't return -EIO because that would make the file
  		 * invisible.
  		 */

  		if (rr->len < 3)
  			goto out;	/* Something got screwed up here */

  		sig = isonum_721(rs.chr);

  		if (rock_check_overflow(&rs, sig))
  			goto eio;

  		rs.chr += rr->len;
  		rs.len -= rr->len;

  		/*
  		 * As above, just ignore the rock ridge info if rr->len
  		 * is bogus.
  		 */

  		if (rs.len < 0)

  			goto out;	/* Something got screwed up here */

  
  		switch (sig) {

  #ifndef CONFIG_ZISOFS		/* No flag for SF or ZF */

  		case SIG('R', 'R'):
  			if ((rr->u.RR.flags[0] &
  			     (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
  				goto out;
  			break;

  #endif

  		case SIG('S', 'P'):

  			if (check_sp(rr, inode))
  				goto out;

  			break;
  		case SIG('C', 'E'):

  			rs.cont_extent = isonum_733(rr->u.CE.extent);
  			rs.cont_offset = isonum_733(rr->u.CE.offset);
  			rs.cont_size = isonum_733(rr->u.CE.size);

  			break;
  		case SIG('E', 'R'):
  			ISOFS_SB(inode->i_sb)->s_rock = 1;
  			printk(KERN_DEBUG "ISO 9660 Extensions: ");
  			{
  				int p;
  				for (p = 0; p < rr->u.ER.len_id; p++)
  					printk("%c", rr->u.ER.data[p]);
  			}
  			printk("
  ");
  			break;
  		case SIG('P', 'X'):
  			inode->i_mode = isonum_733(rr->u.PX.mode);

  			set_nlink(inode, isonum_733(rr->u.PX.n_links));

  			inode->i_uid = isonum_733(rr->u.PX.uid);
  			inode->i_gid = isonum_733(rr->u.PX.gid);
  			break;
  		case SIG('P', 'N'):
  			{
  				int high, low;
  				high = isonum_733(rr->u.PN.dev_high);
  				low = isonum_733(rr->u.PN.dev_low);
  				/*
  				 * The Rock Ridge standard specifies that if
  				 * sizeof(dev_t) <= 4, then the high field is
  				 * unused, and the device number is completely
  				 * stored in the low field.  Some writers may
  				 * ignore this subtlety,
  				 * and as a result we test to see if the entire
  				 * device number is
  				 * stored in the low field, and use that.
  				 */
  				if ((low & ~0xff) && high == 0) {
  					inode->i_rdev =
  					    MKDEV(low >> 8, low & 0xff);
  				} else {
  					inode->i_rdev =
  					    MKDEV(high, low);

  				}

  			}
  			break;
  		case SIG('T', 'F'):
  			/*
  			 * Some RRIP writers incorrectly place ctime in the
  			 * TF_CREATE field. Try to handle this correctly for
  			 * either case.
  			 */
  			/* Rock ridge never appears on a High Sierra disk */
  			cnt = 0;
  			if (rr->u.TF.flags & TF_CREATE) {
  				inode->i_ctime.tv_sec =
  				    iso_date(rr->u.TF.times[cnt++].time,
  					     0);
  				inode->i_ctime.tv_nsec = 0;
  			}
  			if (rr->u.TF.flags & TF_MODIFY) {
  				inode->i_mtime.tv_sec =
  				    iso_date(rr->u.TF.times[cnt++].time,
  					     0);
  				inode->i_mtime.tv_nsec = 0;
  			}
  			if (rr->u.TF.flags & TF_ACCESS) {
  				inode->i_atime.tv_sec =
  				    iso_date(rr->u.TF.times[cnt++].time,
  					     0);
  				inode->i_atime.tv_nsec = 0;
  			}
  			if (rr->u.TF.flags & TF_ATTRIBUTES) {
  				inode->i_ctime.tv_sec =
  				    iso_date(rr->u.TF.times[cnt++].time,
  					     0);
  				inode->i_ctime.tv_nsec = 0;
  			}
  			break;
  		case SIG('S', 'L'):
  			{
  				int slen;
  				struct SL_component *slp;
  				struct SL_component *oldslp;
  				slen = rr->len - 5;
  				slp = &rr->u.SL.link;
  				inode->i_size = symlink_len;
  				while (slen > 1) {
  					rootflag = 0;
  					switch (slp->flags & ~1) {
  					case 0:
  						inode->i_size +=
  						    slp->len;
  						break;
  					case 2:
  						inode->i_size += 1;
  						break;
  					case 4:
  						inode->i_size += 2;
  						break;
  					case 8:
  						rootflag = 1;
  						inode->i_size += 1;
  						break;
  					default:
  						printk("Symlink component flag "
  							"not implemented
  ");

  					}

  					slen -= slp->len + 2;
  					oldslp = slp;
  					slp = (struct SL_component *)
  						(((char *)slp) + slp->len + 2);
  
  					if (slen < 2) {
  						if (((rr->u.SL.
  						      flags & 1) != 0)
  						    &&
  						    ((oldslp->
  						      flags & 1) == 0))

  							inode->i_size +=

  							    1;
  						break;

  					}

  
  					/*
  					 * If this component record isn't
  					 * continued, then append a '/'.
  					 */
  					if (!rootflag
  					    && (oldslp->flags & 1) == 0)
  						inode->i_size += 1;

  				}

  			}
  			symlink_len = inode->i_size;
  			break;
  		case SIG('R', 'E'):
  			printk(KERN_WARNING "Attempt to read inode for "
  					"relocated directory
  ");
  			goto out;
  		case SIG('C', 'L'):
  			ISOFS_I(inode)->i_first_extent =
  			    isonum_733(rr->u.CL.location);
  			reloc =
  			    isofs_iget(inode->i_sb,
  				       ISOFS_I(inode)->i_first_extent,
  				       0);

  			if (IS_ERR(reloc)) {
  				ret = PTR_ERR(reloc);

  				goto out;

  			}

  			inode->i_mode = reloc->i_mode;

  			set_nlink(inode, reloc->i_nlink);

  			inode->i_uid = reloc->i_uid;
  			inode->i_gid = reloc->i_gid;
  			inode->i_rdev = reloc->i_rdev;
  			inode->i_size = reloc->i_size;
  			inode->i_blocks = reloc->i_blocks;
  			inode->i_atime = reloc->i_atime;
  			inode->i_ctime = reloc->i_ctime;
  			inode->i_mtime = reloc->i_mtime;
  			iput(reloc);
  			break;

  #ifdef CONFIG_ZISOFS

  		case SIG('Z', 'F'): {
  			int algo;
  
  			if (ISOFS_SB(inode->i_sb)->s_nocompress)

  				break;

  			algo = isonum_721(rr->u.ZF.algorithm);
  			if (algo == SIG('p', 'z')) {
  				int block_shift =
  					isonum_711(&rr->u.ZF.parms[1]);

  				if (block_shift > 17) {

  					printk(KERN_WARNING "isofs: "
  						"Can't handle ZF block "
  						"size of 2^%d
  ",
  						block_shift);
  				} else {
  					/*
  					 * Note: we don't change
  					 * i_blocks here
  					 */
  					ISOFS_I(inode)->i_file_format =
  						isofs_file_compressed;
  					/*
  					 * Parameters to compression
  					 * algorithm (header size,
  					 * block size)
  					 */
  					ISOFS_I(inode)->i_format_parm[0] =
  						isonum_711(&rr->u.ZF.parms[0]);
  					ISOFS_I(inode)->i_format_parm[1] =
  						isonum_711(&rr->u.ZF.parms[1]);
  					inode->i_size =
  					    isonum_733(rr->u.ZF.
  						       real_size);
  				}
  			} else {
  				printk(KERN_WARNING
  				       "isofs: Unknown ZF compression "
  						"algorithm: %c%c
  ",
  				       rr->u.ZF.algorithm[0],
  				       rr->u.ZF.algorithm[1]);

  			}

  			break;
  		}
  #endif
  		default:
  			break;

  		}
  	}

  	ret = rock_continue(&rs);
  	if (ret == 0)
  		goto repeat;
  	if (ret == 1)
  		ret = 0;

  out:

  	kfree(rs.buffer);
  	return ret;

  eio:
  	ret = -EIO;
  	goto out;

  }
  
  static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
  {
  	int slen;
  	int rootflag;
  	struct SL_component *oldslp;
  	struct SL_component *slp;
  	slen = rr->len - 5;
  	slp = &rr->u.SL.link;
  	while (slen > 1) {
  		rootflag = 0;
  		switch (slp->flags & ~1) {
  		case 0:
  			if (slp->len > plimit - rpnt)
  				return NULL;
  			memcpy(rpnt, slp->text, slp->len);

  			rpnt += slp->len;

  			break;
  		case 2:
  			if (rpnt >= plimit)
  				return NULL;

  			*rpnt++ = '.';

  			break;
  		case 4:
  			if (2 > plimit - rpnt)
  				return NULL;

  			*rpnt++ = '.';
  			*rpnt++ = '.';

  			break;
  		case 8:
  			if (rpnt >= plimit)
  				return NULL;
  			rootflag = 1;

  			*rpnt++ = '/';

  			break;
  		default:
  			printk("Symlink component flag not implemented (%d)
  ",

  			       slp->flags);

  		}
  		slen -= slp->len + 2;
  		oldslp = slp;

  		slp = (struct SL_component *)((char *)slp + slp->len + 2);

  
  		if (slen < 2) {
  			/*
  			 * If there is another SL record, and this component
  			 * record isn't continued, then add a slash.
  			 */
  			if ((!rootflag) && (rr->u.SL.flags & 1) &&
  			    !(oldslp->flags & 1)) {
  				if (rpnt >= plimit)
  					return NULL;

  				*rpnt++ = '/';

  			}
  			break;
  		}
  
  		/*
  		 * If this component record isn't continued, then append a '/'.
  		 */
  		if (!rootflag && !(oldslp->flags & 1)) {
  			if (rpnt >= plimit)
  				return NULL;

  			*rpnt++ = '/';

  		}
  	}
  	return rpnt;
  }

  int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)

  {

  	int result = parse_rock_ridge_inode_internal(de, inode, 0);

  
  	/*
  	 * if rockridge flag was reset and we didn't look for attributes
  	 * behind eventual XA attributes, have a look there
  	 */

  	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
  	    && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
  		result = parse_rock_ridge_inode_internal(de, inode, 14);
  	}
  	return result;

  }

  /*
   * readpage() for symlinks: reads symlink contents into the page and either
   * makes it uptodate and returns 0 or returns error (-EIO)
   */

  static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
  {
  	struct inode *inode = page->mapping->host;

  	struct iso_inode_info *ei = ISOFS_I(inode);

  	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);

  	char *link = kmap(page);
  	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
  	struct buffer_head *bh;
  	char *rpnt = link;
  	unsigned char *pnt;

  	struct iso_directory_record *raw_de;

  	unsigned long block, offset;
  	int sig;

  	struct rock_ridge *rr;

  	struct rock_state rs;
  	int ret;

  	if (!sbi->s_rock)

  		goto error;

  	init_rock_state(&rs, inode);

  	block = ei->i_iget5_block;

  	bh = sb_bread(inode->i_sb, block);
  	if (!bh)
  		goto out_noread;

  	offset = ei->i_iget5_offset;
  	pnt = (unsigned char *)bh->b_data + offset;

  	raw_de = (struct iso_directory_record *)pnt;

  
  	/*
  	 * If we go past the end of the buffer, there is some sort of error.
  	 */
  	if (offset + *pnt > bufsize)
  		goto out_bad_span;

  	/*
  	 * Now test for possible Rock Ridge extensions which will override
  	 * some of these numbers in the inode structure.
  	 */

  	setup_rock_ridge(raw_de, inode, &rs);

  repeat:

  	while (rs.len > 2) { /* There may be one byte for padding somewhere */
  		rr = (struct rock_ridge *)rs.chr;

  		if (rr->len < 3)
  			goto out;	/* Something got screwed up here */

  		sig = isonum_721(rs.chr);

  		if (rock_check_overflow(&rs, sig))
  			goto out;

  		rs.chr += rr->len;
  		rs.len -= rr->len;
  		if (rs.len < 0)

  			goto out;	/* corrupted isofs */
  
  		switch (sig) {
  		case SIG('R', 'R'):
  			if ((rr->u.RR.flags[0] & RR_SL) == 0)
  				goto out;
  			break;
  		case SIG('S', 'P'):

  			if (check_sp(rr, inode))
  				goto out;

  			break;
  		case SIG('S', 'L'):
  			rpnt = get_symlink_chunk(rpnt, rr,
  						 link + (PAGE_SIZE - 1));
  			if (rpnt == NULL)
  				goto out;
  			break;
  		case SIG('C', 'E'):
  			/* This tells is if there is a continuation record */

  			rs.cont_extent = isonum_733(rr->u.CE.extent);
  			rs.cont_offset = isonum_733(rr->u.CE.offset);
  			rs.cont_size = isonum_733(rr->u.CE.size);

  		default:
  			break;
  		}
  	}

  	ret = rock_continue(&rs);
  	if (ret == 0)
  		goto repeat;
  	if (ret < 0)
  		goto fail;

  
  	if (rpnt == link)
  		goto fail;
  	brelse(bh);
  	*rpnt = '\0';

  	SetPageUptodate(page);
  	kunmap(page);
  	unlock_page(page);
  	return 0;
  
  	/* error exit from macro */

  out:

  	kfree(rs.buffer);

  	goto fail;

  out_noread:

  	printk("unable to read i-node block");
  	goto fail;

  out_bad_span:

  	printk("symlink spans iso9660 blocks
  ");

  fail:

  	brelse(bh);

  error:

  	SetPageError(page);
  	kunmap(page);
  	unlock_page(page);
  	return -EIO;
  }

  const struct address_space_operations isofs_symlink_aops = {

  	.readpage = rock_ridge_symlink_readpage

  };