/*
   *  linux/fs/fat/file.c
   *
   *  Written 1992,1993 by Werner Almesberger
   *
   *  regular file handling primitives for fat-based filesystems
   */

  #include <linux/capability.h>

  #include <linux/module.h>

  #include <linux/mount.h>

  #include <linux/time.h>

  #include <linux/buffer_head.h>

  #include <linux/writeback.h>

  #include <linux/backing-dev.h>

  #include <linux/blkdev.h>

  #include <linux/fsnotify.h>
  #include <linux/security.h>

  #include "fat.h"

  int fat_generic_ioctl(struct inode *inode, struct file *filp,
  		      unsigned int cmd, unsigned long arg)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  	u32 __user *user_attr = (u32 __user *)arg;
  
  	switch (cmd) {
  	case FAT_IOCTL_GET_ATTRIBUTES:
  	{

  		u32 attr;
  
  		mutex_lock(&inode->i_mutex);
  		attr = fat_make_attrs(inode);
  		mutex_unlock(&inode->i_mutex);

  		return put_user(attr, user_attr);
  	}
  	case FAT_IOCTL_SET_ATTRIBUTES:
  	{
  		u32 attr, oldattr;
  		int err, is_dir = S_ISDIR(inode->i_mode);
  		struct iattr ia;
  
  		err = get_user(attr, user_attr);
  		if (err)
  			return err;

  		mutex_lock(&inode->i_mutex);

  		err = mnt_want_write(filp->f_path.mnt);
  		if (err)
  			goto up_no_drop_write;

  
  		/*
  		 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  		 * prevents the user from turning us into a VFAT
  		 * longname entry.  Also, we obviously can't set
  		 * any of the NTFS attributes in the high 24 bits.
  		 */
  		attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  		/* Merge in ATTR_VOLUME and ATTR_DIR */
  		attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  			(is_dir ? ATTR_DIR : 0);

  		oldattr = fat_make_attrs(inode);

  
  		/* Equivalent to a chmod() */
  		ia.ia_valid = ATTR_MODE | ATTR_CTIME;

  		ia.ia_ctime = current_fs_time(inode->i_sb);

  		if (is_dir)
  			ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
  		else {
  			ia.ia_mode = fat_make_mode(sbi, attr,
  				S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));

  		}
  
  		/* The root directory has no attributes */
  		if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  			err = -EINVAL;
  			goto up;
  		}
  
  		if (sbi->options.sys_immutable) {
  			if ((attr | oldattr) & ATTR_SYS) {
  				if (!capable(CAP_LINUX_IMMUTABLE)) {
  					err = -EPERM;
  					goto up;
  				}
  			}
  		}

  		/*
  		 * The security check is questionable...  We single
  		 * out the RO attribute for checking by the security
  		 * module, just because it maps to a file mode.
  		 */
  		err = security_inode_setattr(filp->f_path.dentry, &ia);
  		if (err)
  			goto up;

  		/* This MUST be done before doing anything irreversible... */

  		err = fat_setattr(filp->f_path.dentry, &ia);

  		if (err)
  			goto up;

  		fsnotify_change(filp->f_path.dentry, ia.ia_valid);

  		if (sbi->options.sys_immutable) {
  			if (attr & ATTR_SYS)
  				inode->i_flags |= S_IMMUTABLE;
  			else
  				inode->i_flags &= S_IMMUTABLE;
  		}

  		fat_save_attrs(inode, attr);

  		mark_inode_dirty(inode);

  up:
  		mnt_drop_write(filp->f_path.mnt);
  up_no_drop_write:

  		mutex_unlock(&inode->i_mutex);

  		return err;
  	}
  	default:
  		return -ENOTTY;	/* Inappropriate ioctl for device */
  	}
  }

  static int fat_file_release(struct inode *inode, struct file *filp)
  {
  	if ((filp->f_mode & FMODE_WRITE) &&
  	     MSDOS_SB(inode->i_sb)->options.flush) {
  		fat_flush_inodes(inode->i_sb, inode, NULL);

  		congestion_wait(WRITE, HZ/10);

  	}
  	return 0;
  }

  const struct file_operations fat_file_operations = {

  	.llseek		= generic_file_llseek,
  	.read		= do_sync_read,
  	.write		= do_sync_write,

  	.aio_read	= generic_file_aio_read,

  	.aio_write	= generic_file_aio_write,

  	.mmap		= generic_file_mmap,

  	.release	= fat_file_release,

  	.ioctl		= fat_generic_ioctl,
  	.fsync		= file_fsync,

  	.splice_read	= generic_file_splice_read,

  };

  static int fat_cont_expand(struct inode *inode, loff_t size)
  {
  	struct address_space *mapping = inode->i_mapping;
  	loff_t start = inode->i_size, count = size - inode->i_size;
  	int err;
  
  	err = generic_cont_expand_simple(inode, size);
  	if (err)
  		goto out;
  
  	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
  	mark_inode_dirty(inode);
  	if (IS_SYNC(inode))
  		err = sync_page_range_nolock(inode, mapping, start, count);
  out:
  	return err;
  }

  /* Free all clusters after the skip'th cluster. */
  static int fat_free(struct inode *inode, int skip)
  {
  	struct super_block *sb = inode->i_sb;
  	int err, wait, free_start, i_start, i_logstart;
  
  	if (MSDOS_I(inode)->i_start == 0)
  		return 0;

  	fat_cache_inval_inode(inode);

  	wait = IS_DIRSYNC(inode);

  	i_start = free_start = MSDOS_I(inode)->i_start;
  	i_logstart = MSDOS_I(inode)->i_logstart;
  
  	/* First, we write the new file size. */
  	if (!skip) {
  		MSDOS_I(inode)->i_start = 0;
  		MSDOS_I(inode)->i_logstart = 0;
  	}
  	MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
  	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
  	if (wait) {
  		err = fat_sync_inode(inode);
  		if (err) {
  			MSDOS_I(inode)->i_start = i_start;
  			MSDOS_I(inode)->i_logstart = i_logstart;
  			return err;
  		}
  	} else
  		mark_inode_dirty(inode);
  
  	/* Write a new EOF, and get the remaining cluster chain for freeing. */

  	if (skip) {
  		struct fat_entry fatent;
  		int ret, fclus, dclus;
  
  		ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
  		if (ret < 0)
  			return ret;
  		else if (ret == FAT_ENT_EOF)
  			return 0;
  
  		fatent_init(&fatent);
  		ret = fat_ent_read(inode, &fatent, dclus);
  		if (ret == FAT_ENT_EOF) {
  			fatent_brelse(&fatent);
  			return 0;
  		} else if (ret == FAT_ENT_FREE) {
  			fat_fs_panic(sb,
  				     "%s: invalid cluster chain (i_pos %lld)",

  				     __func__, MSDOS_I(inode)->i_pos);

  			ret = -EIO;
  		} else if (ret > 0) {
  			err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
  			if (err)
  				ret = err;
  		}
  		fatent_brelse(&fatent);
  		if (ret < 0)
  			return ret;
  
  		free_start = ret;

  	}

  	inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
  
  	/* Freeing the remained cluster chain */
  	return fat_free_clusters(inode, free_start);

  }
  
  void fat_truncate(struct inode *inode)
  {

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

  	const unsigned int cluster_size = sbi->cluster_size;
  	int nr_clusters;
  
  	/*
  	 * This protects against truncating a file bigger than it was then
  	 * trying to write into the hole.
  	 */
  	if (MSDOS_I(inode)->mmu_private > inode->i_size)
  		MSDOS_I(inode)->mmu_private = inode->i_size;
  
  	nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;

  	fat_free(inode, nr_clusters);

  	fat_flush_inodes(inode->i_sb, inode, NULL);

  }

  int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  {
  	struct inode *inode = dentry->d_inode;
  	generic_fillattr(inode, stat);
  	stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(fat_getattr);

  static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
  			     struct inode *inode, umode_t *mode_ptr)

  {

  	mode_t mask, perm;

  	/*
  	 * Note, the basic check is already done by a caller of

  	 * (attr->ia_mode & ~FAT_VALID_MODE)

  	 */
  
  	if (S_ISREG(inode->i_mode))

  		mask = sbi->options.fs_fmask;
  	else
  		mask = sbi->options.fs_dmask;

  	perm = *mode_ptr & ~(S_IFMT | mask);

  	/*
  	 * Of the r and x bits, all (subject to umask) must be present. Of the
  	 * w bits, either all (subject to umask) or none must be present.

  	 *
  	 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.

  	 */

  	if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))

  		return -EPERM;

  	if (fat_mode_can_hold_ro(inode)) {
  		if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
  			return -EPERM;
  	} else {
  		if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
  			return -EPERM;
  	}

  	*mode_ptr &= S_IFMT | perm;

  	return 0;
  }

  static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
  {
  	mode_t allow_utime = sbi->options.allow_utime;
  
  	if (current->fsuid != inode->i_uid) {
  		if (in_group_p(inode->i_gid))
  			allow_utime >>= 3;
  		if (allow_utime & MAY_WRITE)
  			return 1;
  	}
  
  	/* use a default check */
  	return 0;
  }

  #define TIMES_SET_FLAGS	(ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)

  /* valid file mode bits */
  #define FAT_VALID_MODE	(S_IFREG | S_IFDIR | S_IRWXUGO)

  int fat_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
  	struct inode *inode = dentry->d_inode;

  	unsigned int ia_valid;

  	int error;

  	/*
  	 * Expand the file. Since inode_setattr() updates ->i_size
  	 * before calling the ->truncate(), but FAT needs to fill the
  	 * hole before it.
  	 */
  	if (attr->ia_valid & ATTR_SIZE) {
  		if (attr->ia_size > inode->i_size) {
  			error = fat_cont_expand(inode, attr->ia_size);
  			if (error || attr->ia_valid == ATTR_SIZE)
  				goto out;
  			attr->ia_valid &= ~ATTR_SIZE;
  		}
  	}

  	/* Check for setting the inode time. */
  	ia_valid = attr->ia_valid;

  	if (ia_valid & TIMES_SET_FLAGS) {

  		if (fat_allow_set_time(sbi, inode))

  			attr->ia_valid &= ~TIMES_SET_FLAGS;

  	}

  	error = inode_change_ok(inode, attr);

  	attr->ia_valid = ia_valid;

  	if (error) {
  		if (sbi->options.quiet)
  			error = 0;
  		goto out;
  	}

  	if (((attr->ia_valid & ATTR_UID) &&
  	     (attr->ia_uid != sbi->options.fs_uid)) ||
  	    ((attr->ia_valid & ATTR_GID) &&

  	     (attr->ia_gid != sbi->options.fs_gid)) ||
  	    ((attr->ia_valid & ATTR_MODE) &&

  	     (attr->ia_mode & ~FAT_VALID_MODE)))

  		error = -EPERM;
  
  	if (error) {
  		if (sbi->options.quiet)
  			error = 0;
  		goto out;
  	}

  	/*
  	 * We don't return -EPERM here. Yes, strange, but this is too
  	 * old behavior.
  	 */
  	if (attr->ia_valid & ATTR_MODE) {
  		if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
  			attr->ia_valid &= ~ATTR_MODE;
  	}

  	if (attr->ia_valid)
  		error = inode_setattr(inode, attr);

  out:

  	return error;
  }
  EXPORT_SYMBOL_GPL(fat_setattr);

  const struct inode_operations fat_file_inode_operations = {

  	.truncate	= fat_truncate,

  	.setattr	= fat_setattr,

  	.getattr	= fat_getattr,

  };