/*
   *  linux/fs/msdos/namei.c
   *
   *  Written 1992,1993 by Werner Almesberger
   *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
   *  Rewritten for constant inumbers 1999 by Al Viro
   */
  
  #include <linux/module.h>
  #include <linux/time.h>
  #include <linux/buffer_head.h>

  #include "fat.h"

  /* Characters that are undesirable in an MS-DOS file name */
  static unsigned char bad_chars[] = "*?<>|\"";

  static unsigned char bad_if_strict[] = "+=,; ";

  
  /***** Formats an MS-DOS file name. Rejects invalid names. */
  static int msdos_format_name(const unsigned char *name, int len,
  			     unsigned char *res, struct fat_mount_options *opts)
  	/*
  	 * name is the proposed name, len is its length, res is
  	 * the resulting name, opts->name_check is either (r)elaxed,
  	 * (n)ormal or (s)trict, opts->dotsOK allows dots at the
  	 * beginning of name (for hidden files)
  	 */
  {
  	unsigned char *walk;

  	unsigned char c;
  	int space;
  
  	if (name[0] == '.') {	/* dotfile because . and .. already done */
  		if (opts->dotsOK) {
  			/* Get rid of dot - test for it elsewhere */
  			name++;
  			len--;

  		} else

  			return -EINVAL;
  	}
  	/*

  	 * disallow names that _really_ start with a dot

  	 */

  	space = 1;

  	c = 0;
  	for (walk = res; len && walk - res < 8; walk++) {
  		c = *name++;
  		len--;
  		if (opts->name_check != 'r' && strchr(bad_chars, c))
  			return -EINVAL;

  		if (opts->name_check == 's' && strchr(bad_if_strict, c))

  			return -EINVAL;
  		if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
  			return -EINVAL;
  		if (c < ' ' || c == ':' || c == '\\')
  			return -EINVAL;
  	/*
  	 * 0xE5 is legal as a first character, but we must substitute
  	 * 0x05 because 0xE5 marks deleted files.  Yes, DOS really
  	 * does this.
  	 * It seems that Microsoft hacked DOS to support non-US
  	 * characters after the 0xE5 character was already in use to
  	 * mark deleted files.
  	 */
  		if ((res == walk) && (c == 0xE5))
  			c = 0x05;
  		if (c == '.')
  			break;
  		space = (c == ' ');
  		*walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c;
  	}
  	if (space)
  		return -EINVAL;
  	if (opts->name_check == 's' && len && c != '.') {
  		c = *name++;
  		len--;
  		if (c != '.')
  			return -EINVAL;
  	}
  	while (c != '.' && len--)
  		c = *name++;
  	if (c == '.') {
  		while (walk - res < 8)
  			*walk++ = ' ';
  		while (len > 0 && walk - res < MSDOS_NAME) {
  			c = *name++;
  			len--;
  			if (opts->name_check != 'r' && strchr(bad_chars, c))
  				return -EINVAL;
  			if (opts->name_check == 's' &&

  			    strchr(bad_if_strict, c))

  				return -EINVAL;
  			if (c < ' ' || c == ':' || c == '\\')
  				return -EINVAL;
  			if (c == '.') {
  				if (opts->name_check == 's')
  					return -EINVAL;
  				break;
  			}
  			if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
  				return -EINVAL;
  			space = c == ' ';
  			if (!opts->nocase && c >= 'a' && c <= 'z')
  				*walk++ = c - 32;
  			else
  				*walk++ = c;
  		}
  		if (space)
  			return -EINVAL;
  		if (opts->name_check == 's' && len)
  			return -EINVAL;
  	}
  	while (walk - res < MSDOS_NAME)
  		*walk++ = ' ';

  	return 0;
  }
  
  /***** Locates a directory entry.  Uses unformatted name. */
  static int msdos_find(struct inode *dir, const unsigned char *name, int len,
  		      struct fat_slot_info *sinfo)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
  	unsigned char msdos_name[MSDOS_NAME];
  	int err;
  
  	err = msdos_format_name(name, len, msdos_name, &sbi->options);
  	if (err)
  		return -ENOENT;
  
  	err = fat_scan(dir, msdos_name, sinfo);
  	if (!err && sbi->options.dotsOK) {
  		if (name[0] == '.') {
  			if (!(sinfo->de->attr & ATTR_HIDDEN))
  				err = -ENOENT;
  		} else {
  			if (sinfo->de->attr & ATTR_HIDDEN)
  				err = -ENOENT;
  		}
  		if (err)
  			brelse(sinfo->bh);
  	}
  	return err;
  }
  
  /*
   * Compute the hash for the msdos name corresponding to the dentry.
   * Note: if the name is invalid, we leave the hash code unchanged so
   * that the existing dentry can be used. The msdos fs routines will
   * return ENOENT or EINVAL as appropriate.
   */

  static int msdos_hash(const struct dentry *dentry, const struct inode *inode,
  	       struct qstr *qstr)

  {
  	struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
  	unsigned char msdos_name[MSDOS_NAME];
  	int error;
  
  	error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
  	if (!error)
  		qstr->hash = full_name_hash(msdos_name, MSDOS_NAME);
  	return 0;
  }
  
  /*
   * Compare two msdos names. If either of the names are invalid,
   * we fall back to doing the standard name comparison.
   */

  static int msdos_cmp(const struct dentry *parent, const struct inode *pinode,
  		const struct dentry *dentry, const struct inode *inode,
  		unsigned int len, const char *str, const struct qstr *name)

  {

  	struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options;

  	unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
  	int error;

  	error = msdos_format_name(name->name, name->len, a_msdos_name, options);

  	if (error)
  		goto old_compare;

  	error = msdos_format_name(str, len, b_msdos_name, options);

  	if (error)
  		goto old_compare;
  	error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
  out:
  	return error;
  
  old_compare:
  	error = 1;

  	if (name->len == len)
  		error = memcmp(name->name, str, len);

  	goto out;
  }

  static const struct dentry_operations msdos_dentry_operations = {

  	.d_hash		= msdos_hash,
  	.d_compare	= msdos_cmp,
  };
  
  /*
   * AV. Wrappers for FAT sb operations. Is it wise?
   */
  
  /***** Get inode using directory and name */
  static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry,
  				   struct nameidata *nd)
  {
  	struct super_block *sb = dir->i_sb;
  	struct fat_slot_info sinfo;

  	struct inode *inode;
  	int err;

  	lock_super(sb);

  	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);

  	switch (err) {
  	case -ENOENT:
  		inode = NULL;
  		break;
  	case 0:
  		inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
  		brelse(sinfo.bh);
  		break;
  	default:
  		inode = ERR_PTR(err);

  	}

  	unlock_super(sb);

  	return d_splice_alias(inode, dentry);

  }
  
  /***** Creates a directory entry (name is already formatted). */
  static int msdos_add_entry(struct inode *dir, const unsigned char *name,
  			   int is_dir, int is_hid, int cluster,
  			   struct timespec *ts, struct fat_slot_info *sinfo)
  {

  	struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);

  	struct msdos_dir_entry de;
  	__le16 time, date;
  	int err;
  
  	memcpy(de.name, name, MSDOS_NAME);
  	de.attr = is_dir ? ATTR_DIR : ATTR_ARCH;
  	if (is_hid)
  		de.attr |= ATTR_HIDDEN;
  	de.lcase = 0;

  	fat_time_unix2fat(sbi, ts, &time, &date, NULL);

  	de.cdate = de.adate = 0;
  	de.ctime = 0;
  	de.ctime_cs = 0;
  	de.time = time;
  	de.date = date;
  	de.start = cpu_to_le16(cluster);
  	de.starthi = cpu_to_le16(cluster >> 16);
  	de.size = 0;
  
  	err = fat_add_entries(dir, &de, 1, sinfo);
  	if (err)
  		return err;
  
  	dir->i_ctime = dir->i_mtime = *ts;
  	if (IS_DIRSYNC(dir))
  		(void)fat_sync_inode(dir);
  	else
  		mark_inode_dirty(dir);
  
  	return 0;
  }
  
  /***** Create a file */

  static int msdos_create(struct inode *dir, struct dentry *dentry, umode_t mode,

  			struct nameidata *nd)
  {
  	struct super_block *sb = dir->i_sb;

  	struct inode *inode = NULL;

  	struct fat_slot_info sinfo;
  	struct timespec ts;
  	unsigned char msdos_name[MSDOS_NAME];
  	int err, is_hid;

  	lock_super(sb);

  
  	err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
  				msdos_name, &MSDOS_SB(sb)->options);
  	if (err)
  		goto out;
  	is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
  	/* Have to do it due to foo vs. .foo conflicts */
  	if (!fat_scan(dir, msdos_name, &sinfo)) {
  		brelse(sinfo.bh);
  		err = -EINVAL;
  		goto out;
  	}
  
  	ts = CURRENT_TIME_SEC;
  	err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo);
  	if (err)
  		goto out;
  	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
  	brelse(sinfo.bh);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		goto out;
  	}
  	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
  	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
  
  	d_instantiate(dentry, inode);
  out:

  	unlock_super(sb);

  	if (!err)
  		err = fat_flush_inodes(sb, dir, inode);

  	return err;
  }
  
  /***** Remove a directory */
  static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
  {

  	struct super_block *sb = dir->i_sb;

  	struct inode *inode = dentry->d_inode;
  	struct fat_slot_info sinfo;
  	int err;

  	lock_super(sb);

  	/*
  	 * Check whether the directory is not in use, then check
  	 * whether it is empty.
  	 */
  	err = fat_dir_empty(inode);
  	if (err)
  		goto out;
  	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
  	if (err)
  		goto out;
  
  	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
  	if (err)
  		goto out;

  	drop_nlink(dir);

  	clear_nlink(inode);

  	inode->i_ctime = CURRENT_TIME_SEC;
  	fat_detach(inode);
  out:

  	unlock_super(sb);

  	if (!err)

  		err = fat_flush_inodes(sb, dir, inode);

  
  	return err;
  }
  
  /***** Make a directory */

  static int msdos_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)

  {
  	struct super_block *sb = dir->i_sb;
  	struct fat_slot_info sinfo;
  	struct inode *inode;
  	unsigned char msdos_name[MSDOS_NAME];
  	struct timespec ts;
  	int err, is_hid, cluster;

  	lock_super(sb);

  
  	err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
  				msdos_name, &MSDOS_SB(sb)->options);
  	if (err)
  		goto out;
  	is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
  	/* foo vs .foo situation */
  	if (!fat_scan(dir, msdos_name, &sinfo)) {
  		brelse(sinfo.bh);
  		err = -EINVAL;
  		goto out;
  	}
  
  	ts = CURRENT_TIME_SEC;
  	cluster = fat_alloc_new_dir(dir, &ts);
  	if (cluster < 0) {
  		err = cluster;
  		goto out;
  	}
  	err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo);
  	if (err)
  		goto out_free;

  	inc_nlink(dir);

  
  	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
  	brelse(sinfo.bh);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		/* the directory was completed, just return a error */
  		goto out;
  	}

  	set_nlink(inode, 2);

  	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
  	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
  
  	d_instantiate(dentry, inode);

  	unlock_super(sb);

  	fat_flush_inodes(sb, dir, inode);

  	return 0;
  
  out_free:
  	fat_free_clusters(dir, cluster);
  out:

  	unlock_super(sb);

  	return err;
  }
  
  /***** Unlink a file */
  static int msdos_unlink(struct inode *dir, struct dentry *dentry)
  {
  	struct inode *inode = dentry->d_inode;

  	struct super_block *sb= inode->i_sb;

  	struct fat_slot_info sinfo;
  	int err;

  	lock_super(sb);

  	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
  	if (err)
  		goto out;
  
  	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
  	if (err)
  		goto out;

  	clear_nlink(inode);

  	inode->i_ctime = CURRENT_TIME_SEC;
  	fat_detach(inode);
  out:

  	unlock_super(sb);

  	if (!err)

  		err = fat_flush_inodes(sb, dir, inode);

  
  	return err;
  }
  
  static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
  			   struct dentry *old_dentry,
  			   struct inode *new_dir, unsigned char *new_name,
  			   struct dentry *new_dentry, int is_hid)
  {
  	struct buffer_head *dotdot_bh;
  	struct msdos_dir_entry *dotdot_de;

  	struct inode *old_inode, *new_inode;
  	struct fat_slot_info old_sinfo, sinfo;
  	struct timespec ts;

  	loff_t dotdot_i_pos, new_i_pos;

  	int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
  
  	old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
  	old_inode = old_dentry->d_inode;
  	new_inode = new_dentry->d_inode;
  
  	err = fat_scan(old_dir, old_name, &old_sinfo);
  	if (err) {
  		err = -EIO;
  		goto out;
  	}
  
  	is_dir = S_ISDIR(old_inode->i_mode);
  	update_dotdot = (is_dir && old_dir != new_dir);
  	if (update_dotdot) {
  		if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
  					 &dotdot_i_pos) < 0) {
  			err = -EIO;
  			goto out;
  		}
  	}
  
  	old_attrs = MSDOS_I(old_inode)->i_attrs;
  	err = fat_scan(new_dir, new_name, &sinfo);
  	if (!err) {
  		if (!new_inode) {
  			/* "foo" -> ".foo" case. just change the ATTR_HIDDEN */
  			if (sinfo.de != old_sinfo.de) {
  				err = -EINVAL;
  				goto out;
  			}
  			if (is_hid)
  				MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
  			else
  				MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
  			if (IS_DIRSYNC(old_dir)) {
  				err = fat_sync_inode(old_inode);
  				if (err) {
  					MSDOS_I(old_inode)->i_attrs = old_attrs;
  					goto out;
  				}
  			} else
  				mark_inode_dirty(old_inode);
  
  			old_dir->i_version++;
  			old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
  			if (IS_DIRSYNC(old_dir))
  				(void)fat_sync_inode(old_dir);
  			else
  				mark_inode_dirty(old_dir);
  			goto out;
  		}
  	}
  
  	ts = CURRENT_TIME_SEC;
  	if (new_inode) {
  		if (err)
  			goto out;

  		if (is_dir) {
  			err = fat_dir_empty(new_inode);
  			if (err)
  				goto out;
  		}

  		new_i_pos = MSDOS_I(new_inode)->i_pos;

  		fat_detach(new_inode);
  	} else {
  		err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0,
  				      &ts, &sinfo);
  		if (err)
  			goto out;

  		new_i_pos = sinfo.i_pos;

  	}
  	new_dir->i_version++;
  
  	fat_detach(old_inode);

  	fat_attach(old_inode, new_i_pos);

  	if (is_hid)
  		MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
  	else
  		MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
  	if (IS_DIRSYNC(new_dir)) {
  		err = fat_sync_inode(old_inode);
  		if (err)
  			goto error_inode;
  	} else
  		mark_inode_dirty(old_inode);
  
  	if (update_dotdot) {
  		int start = MSDOS_I(new_dir)->i_logstart;
  		dotdot_de->start = cpu_to_le16(start);
  		dotdot_de->starthi = cpu_to_le16(start >> 16);

  		mark_buffer_dirty_inode(dotdot_bh, old_inode);

  		if (IS_DIRSYNC(new_dir)) {
  			err = sync_dirty_buffer(dotdot_bh);
  			if (err)
  				goto error_dotdot;
  		}

  		drop_nlink(old_dir);

  		if (!new_inode)

  			inc_nlink(new_dir);

  	}
  
  	err = fat_remove_entries(old_dir, &old_sinfo);	/* and releases bh */
  	old_sinfo.bh = NULL;
  	if (err)
  		goto error_dotdot;
  	old_dir->i_version++;
  	old_dir->i_ctime = old_dir->i_mtime = ts;
  	if (IS_DIRSYNC(old_dir))
  		(void)fat_sync_inode(old_dir);
  	else
  		mark_inode_dirty(old_dir);
  
  	if (new_inode) {

  		drop_nlink(new_inode);

  		if (is_dir)

  			drop_nlink(new_inode);

  		new_inode->i_ctime = ts;
  	}
  out:
  	brelse(sinfo.bh);
  	brelse(dotdot_bh);
  	brelse(old_sinfo.bh);
  	return err;
  
  error_dotdot:
  	/* data cluster is shared, serious corruption */
  	corrupt = 1;
  
  	if (update_dotdot) {
  		int start = MSDOS_I(old_dir)->i_logstart;
  		dotdot_de->start = cpu_to_le16(start);
  		dotdot_de->starthi = cpu_to_le16(start >> 16);

  		mark_buffer_dirty_inode(dotdot_bh, old_inode);

  		corrupt |= sync_dirty_buffer(dotdot_bh);
  	}
  error_inode:
  	fat_detach(old_inode);
  	fat_attach(old_inode, old_sinfo.i_pos);
  	MSDOS_I(old_inode)->i_attrs = old_attrs;
  	if (new_inode) {

  		fat_attach(new_inode, new_i_pos);

  		if (corrupt)
  			corrupt |= fat_sync_inode(new_inode);
  	} else {
  		/*
  		 * If new entry was not sharing the data cluster, it
  		 * shouldn't be serious corruption.
  		 */
  		int err2 = fat_remove_entries(new_dir, &sinfo);
  		if (corrupt)
  			corrupt |= err2;
  		sinfo.bh = NULL;
  	}
  	if (corrupt < 0) {

  		fat_fs_error(new_dir->i_sb,

  			     "%s: Filesystem corrupted (i_pos %lld)",

  			     __func__, sinfo.i_pos);

  	}
  	goto out;
  }
  
  /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */
  static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry,
  			struct inode *new_dir, struct dentry *new_dentry)
  {

  	struct super_block *sb = old_dir->i_sb;

  	unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];
  	int err, is_hid;

  	lock_super(sb);

  
  	err = msdos_format_name(old_dentry->d_name.name,
  				old_dentry->d_name.len, old_msdos_name,
  				&MSDOS_SB(old_dir->i_sb)->options);
  	if (err)
  		goto out;
  	err = msdos_format_name(new_dentry->d_name.name,
  				new_dentry->d_name.len, new_msdos_name,
  				&MSDOS_SB(new_dir->i_sb)->options);
  	if (err)
  		goto out;
  
  	is_hid =
  	     (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.');
  
  	err = do_msdos_rename(old_dir, old_msdos_name, old_dentry,
  			      new_dir, new_msdos_name, new_dentry, is_hid);
  out:

  	unlock_super(sb);

  	if (!err)

  		err = fat_flush_inodes(sb, old_dir, new_dir);

  	return err;
  }

  static const struct inode_operations msdos_dir_inode_operations = {

  	.create		= msdos_create,
  	.lookup		= msdos_lookup,
  	.unlink		= msdos_unlink,
  	.mkdir		= msdos_mkdir,
  	.rmdir		= msdos_rmdir,
  	.rename		= msdos_rename,

  	.setattr	= fat_setattr,

  	.getattr	= fat_getattr,

  };

  static void setup(struct super_block *sb)

  {

  	MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations;

  	sb->s_d_op = &msdos_dentry_operations;

  	sb->s_flags |= MS_NOATIME;

  }
  
  static int msdos_fill_super(struct super_block *sb, void *data, int silent)
  {

  	return fat_fill_super(sb, data, silent, 0, setup);

  }

  static struct dentry *msdos_mount(struct file_system_type *fs_type,

  			int flags, const char *dev_name,

  			void *data)

  {

  	return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super);

  }
  
  static struct file_system_type msdos_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "msdos",

  	.mount		= msdos_mount,

  	.kill_sb	= kill_block_super,
  	.fs_flags	= FS_REQUIRES_DEV,
  };
  
  static int __init init_msdos_fs(void)
  {
  	return register_filesystem(&msdos_fs_type);
  }
  
  static void __exit exit_msdos_fs(void)
  {
  	unregister_filesystem(&msdos_fs_type);
  }
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Werner Almesberger");
  MODULE_DESCRIPTION("MS-DOS filesystem support");
  
  module_init(init_msdos_fs)
  module_exit(exit_msdos_fs)