/*
   *  linux/fs/open.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   */
  
  #include <linux/string.h>
  #include <linux/mm.h>

  #include <linux/file.h>

  #include <linux/quotaops.h>

  #include <linux/fsnotify.h>

  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/tty.h>
  #include <linux/namei.h>
  #include <linux/backing-dev.h>

  #include <linux/capability.h>

  #include <linux/security.h>
  #include <linux/mount.h>
  #include <linux/vfs.h>

  #include <linux/fcntl.h>

  #include <asm/uaccess.h>
  #include <linux/fs.h>

  #include <linux/personality.h>

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

  #include <linux/rcupdate.h>

  #include <linux/audit.h>

  #include <linux/falloc.h>

  int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)

  {
  	int retval = -ENODEV;

  	if (dentry) {

  		retval = -ENOSYS;

  		if (dentry->d_sb->s_op->statfs) {

  			memset(buf, 0, sizeof(*buf));

  			retval = security_sb_statfs(dentry);

  			if (retval)
  				return retval;

  			retval = dentry->d_sb->s_op->statfs(dentry, buf);

  			if (retval == 0 && buf->f_frsize == 0)
  				buf->f_frsize = buf->f_bsize;
  		}
  	}
  	return retval;
  }
  
  EXPORT_SYMBOL(vfs_statfs);

  static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)

  {
  	struct kstatfs st;
  	int retval;

  	retval = vfs_statfs(dentry, &st);

  	if (retval)
  		return retval;
  
  	if (sizeof(*buf) == sizeof(st))
  		memcpy(buf, &st, sizeof(st));
  	else {
  		if (sizeof buf->f_blocks == 4) {
  			if ((st.f_blocks | st.f_bfree | st.f_bavail) &
  			    0xffffffff00000000ULL)
  				return -EOVERFLOW;
  			/*
  			 * f_files and f_ffree may be -1; it's okay to stuff
  			 * that into 32 bits
  			 */
  			if (st.f_files != -1 &&
  			    (st.f_files & 0xffffffff00000000ULL))
  				return -EOVERFLOW;
  			if (st.f_ffree != -1 &&
  			    (st.f_ffree & 0xffffffff00000000ULL))
  				return -EOVERFLOW;
  		}
  
  		buf->f_type = st.f_type;
  		buf->f_bsize = st.f_bsize;
  		buf->f_blocks = st.f_blocks;
  		buf->f_bfree = st.f_bfree;
  		buf->f_bavail = st.f_bavail;
  		buf->f_files = st.f_files;
  		buf->f_ffree = st.f_ffree;
  		buf->f_fsid = st.f_fsid;
  		buf->f_namelen = st.f_namelen;
  		buf->f_frsize = st.f_frsize;
  		memset(buf->f_spare, 0, sizeof(buf->f_spare));
  	}
  	return 0;
  }

  static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)

  {
  	struct kstatfs st;
  	int retval;

  	retval = vfs_statfs(dentry, &st);

  	if (retval)
  		return retval;
  
  	if (sizeof(*buf) == sizeof(st))
  		memcpy(buf, &st, sizeof(st));
  	else {
  		buf->f_type = st.f_type;
  		buf->f_bsize = st.f_bsize;
  		buf->f_blocks = st.f_blocks;
  		buf->f_bfree = st.f_bfree;
  		buf->f_bavail = st.f_bavail;
  		buf->f_files = st.f_files;
  		buf->f_ffree = st.f_ffree;
  		buf->f_fsid = st.f_fsid;
  		buf->f_namelen = st.f_namelen;
  		buf->f_frsize = st.f_frsize;
  		memset(buf->f_spare, 0, sizeof(buf->f_spare));
  	}
  	return 0;
  }
  
  asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
  {
  	struct nameidata nd;
  	int error;
  
  	error = user_path_walk(path, &nd);
  	if (!error) {
  		struct statfs tmp;

  		error = vfs_statfs_native(nd.dentry, &tmp);

  		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
  			error = -EFAULT;
  		path_release(&nd);
  	}
  	return error;
  }
  
  
  asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
  {
  	struct nameidata nd;
  	long error;
  
  	if (sz != sizeof(*buf))
  		return -EINVAL;
  	error = user_path_walk(path, &nd);
  	if (!error) {
  		struct statfs64 tmp;

  		error = vfs_statfs64(nd.dentry, &tmp);

  		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
  			error = -EFAULT;
  		path_release(&nd);
  	}
  	return error;
  }
  
  
  asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
  {
  	struct file * file;
  	struct statfs tmp;
  	int error;
  
  	error = -EBADF;
  	file = fget(fd);
  	if (!file)
  		goto out;

  	error = vfs_statfs_native(file->f_path.dentry, &tmp);

  	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
  		error = -EFAULT;
  	fput(file);
  out:
  	return error;
  }
  
  asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
  {
  	struct file * file;
  	struct statfs64 tmp;
  	int error;
  
  	if (sz != sizeof(*buf))
  		return -EINVAL;
  
  	error = -EBADF;
  	file = fget(fd);
  	if (!file)
  		goto out;

  	error = vfs_statfs64(file->f_path.dentry, &tmp);

  	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
  		error = -EFAULT;
  	fput(file);
  out:
  	return error;
  }

  int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
  	struct file *filp)

  {
  	int err;
  	struct iattr newattrs;
  
  	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  	if (length < 0)
  		return -EINVAL;
  
  	newattrs.ia_size = length;

  	newattrs.ia_valid = ATTR_SIZE | time_attrs;

  	if (filp) {
  		newattrs.ia_file = filp;
  		newattrs.ia_valid |= ATTR_FILE;
  	}

  	/* Remove suid/sgid on truncate too */
  	newattrs.ia_valid |= should_remove_suid(dentry);

  	mutex_lock(&dentry->d_inode->i_mutex);

  	err = notify_change(dentry, &newattrs);

  	mutex_unlock(&dentry->d_inode->i_mutex);

  	return err;
  }

  static long do_sys_truncate(const char __user * path, loff_t length)

  {
  	struct nameidata nd;
  	struct inode * inode;
  	int error;
  
  	error = -EINVAL;
  	if (length < 0)	/* sorry, but loff_t says... */
  		goto out;
  
  	error = user_path_walk(path, &nd);
  	if (error)
  		goto out;
  	inode = nd.dentry->d_inode;
  
  	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
  	error = -EISDIR;
  	if (S_ISDIR(inode->i_mode))
  		goto dput_and_out;
  
  	error = -EINVAL;
  	if (!S_ISREG(inode->i_mode))
  		goto dput_and_out;

  	error = vfs_permission(&nd, MAY_WRITE);

  	if (error)
  		goto dput_and_out;
  
  	error = -EROFS;
  	if (IS_RDONLY(inode))
  		goto dput_and_out;
  
  	error = -EPERM;
  	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  		goto dput_and_out;
  
  	/*
  	 * Make sure that there are no leases.
  	 */
  	error = break_lease(inode, FMODE_WRITE);
  	if (error)
  		goto dput_and_out;
  
  	error = get_write_access(inode);
  	if (error)
  		goto dput_and_out;
  
  	error = locks_verify_truncate(inode, NULL, length);
  	if (!error) {
  		DQUOT_INIT(inode);

  		error = do_truncate(nd.dentry, length, 0, NULL);

  	}
  	put_write_access(inode);
  
  dput_and_out:
  	path_release(&nd);
  out:
  	return error;
  }
  
  asmlinkage long sys_truncate(const char __user * path, unsigned long length)
  {
  	/* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
  	return do_sys_truncate(path, (long)length);
  }

  static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)

  {
  	struct inode * inode;
  	struct dentry *dentry;
  	struct file * file;
  	int error;
  
  	error = -EINVAL;
  	if (length < 0)
  		goto out;
  	error = -EBADF;
  	file = fget(fd);
  	if (!file)
  		goto out;
  
  	/* explicitly opened as large or we are on 64-bit box */
  	if (file->f_flags & O_LARGEFILE)
  		small = 0;

  	dentry = file->f_path.dentry;

  	inode = dentry->d_inode;
  	error = -EINVAL;
  	if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
  		goto out_putf;
  
  	error = -EINVAL;
  	/* Cannot ftruncate over 2^31 bytes without large file support */
  	if (small && length > MAX_NON_LFS)
  		goto out_putf;
  
  	error = -EPERM;
  	if (IS_APPEND(inode))
  		goto out_putf;
  
  	error = locks_verify_truncate(inode, file, length);
  	if (!error)

  		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);

  out_putf:
  	fput(file);
  out:
  	return error;
  }
  
  asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
  {

  	long ret = do_sys_ftruncate(fd, length, 1);

  	/* avoid REGPARM breakage on x86: */

  	prevent_tail_call(ret);
  	return ret;

  }
  
  /* LFS versions of truncate are only needed on 32 bit machines */
  #if BITS_PER_LONG == 32
  asmlinkage long sys_truncate64(const char __user * path, loff_t length)
  {
  	return do_sys_truncate(path, length);
  }
  
  asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
  {

  	long ret = do_sys_ftruncate(fd, length, 0);

  	/* avoid REGPARM breakage on x86: */

  	prevent_tail_call(ret);
  	return ret;

  }
  #endif

  asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
  {
  	struct file *file;
  	struct inode *inode;
  	long ret = -EINVAL;
  
  	if (offset < 0 || len <= 0)
  		goto out;
  
  	/* Return error if mode is not supported */
  	ret = -EOPNOTSUPP;
  	if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
  		goto out;
  
  	ret = -EBADF;
  	file = fget(fd);
  	if (!file)
  		goto out;
  	if (!(file->f_mode & FMODE_WRITE))
  		goto out_fput;
  	/*
  	 * Revalidate the write permissions, in case security policy has
  	 * changed since the files were opened.
  	 */
  	ret = security_file_permission(file, MAY_WRITE);
  	if (ret)
  		goto out_fput;
  
  	inode = file->f_path.dentry->d_inode;
  
  	ret = -ESPIPE;
  	if (S_ISFIFO(inode->i_mode))
  		goto out_fput;
  
  	ret = -ENODEV;
  	/*
  	 * Let individual file system decide if it supports preallocation
  	 * for directories or not.
  	 */
  	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
  		goto out_fput;
  
  	ret = -EFBIG;
  	/* Check for wrap through zero too */
  	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
  		goto out_fput;
  
  	if (inode->i_op && inode->i_op->fallocate)
  		ret = inode->i_op->fallocate(inode, mode, offset, len);
  	else
  		ret = -ENOSYS;
  
  out_fput:
  	fput(file);
  out:
  	return ret;
  }

  /*
   * access() needs to use the real uid/gid, not the effective uid/gid.
   * We do this by temporarily clearing all FS-related capabilities and
   * switching the fsuid/fsgid around to the real ones.
   */

  asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)

  {
  	struct nameidata nd;
  	int old_fsuid, old_fsgid;
  	kernel_cap_t old_cap;
  	int res;
  
  	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
  		return -EINVAL;
  
  	old_fsuid = current->fsuid;
  	old_fsgid = current->fsgid;
  	old_cap = current->cap_effective;
  
  	current->fsuid = current->uid;
  	current->fsgid = current->gid;
  
  	/*
  	 * Clear the capabilities if we switch to a non-root user
  	 *
  	 * FIXME: There is a race here against sys_capset.  The
  	 * capabilities can change yet we will restore the old
  	 * value below.  We should hold task_capabilities_lock,
  	 * but we cannot because user_path_walk can sleep.
  	 */
  	if (current->uid)
  		cap_clear(current->cap_effective);
  	else
  		current->cap_effective = current->cap_permitted;

  	res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);

  	if (res)
  		goto out;
  
  	res = vfs_permission(&nd, mode);
  	/* SuS v2 requires we report a read only fs too */
  	if(res || !(mode & S_IWOTH) ||
  	   special_file(nd.dentry->d_inode->i_mode))
  		goto out_path_release;
  
  	if(IS_RDONLY(nd.dentry->d_inode))
  		res = -EROFS;

  out_path_release:
  	path_release(&nd);
  out:

  	current->fsuid = old_fsuid;
  	current->fsgid = old_fsgid;
  	current->cap_effective = old_cap;
  
  	return res;
  }

  asmlinkage long sys_access(const char __user *filename, int mode)
  {
  	return sys_faccessat(AT_FDCWD, filename, mode);
  }

  asmlinkage long sys_chdir(const char __user * filename)
  {
  	struct nameidata nd;
  	int error;

  	error = __user_walk(filename,
  			    LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);

  	if (error)
  		goto out;

  	error = vfs_permission(&nd, MAY_EXEC);

  	if (error)
  		goto dput_and_out;
  
  	set_fs_pwd(current->fs, nd.mnt, nd.dentry);
  
  dput_and_out:
  	path_release(&nd);
  out:
  	return error;
  }
  
  asmlinkage long sys_fchdir(unsigned int fd)
  {
  	struct file *file;
  	struct dentry *dentry;
  	struct inode *inode;
  	struct vfsmount *mnt;
  	int error;
  
  	error = -EBADF;
  	file = fget(fd);
  	if (!file)
  		goto out;

  	dentry = file->f_path.dentry;
  	mnt = file->f_path.mnt;

  	inode = dentry->d_inode;
  
  	error = -ENOTDIR;
  	if (!S_ISDIR(inode->i_mode))
  		goto out_putf;

  	error = file_permission(file, MAY_EXEC);

  	if (!error)
  		set_fs_pwd(current->fs, mnt, dentry);
  out_putf:
  	fput(file);
  out:
  	return error;
  }
  
  asmlinkage long sys_chroot(const char __user * filename)
  {
  	struct nameidata nd;
  	int error;
  
  	error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
  	if (error)
  		goto out;

  	error = vfs_permission(&nd, MAY_EXEC);

  	if (error)
  		goto dput_and_out;
  
  	error = -EPERM;
  	if (!capable(CAP_SYS_CHROOT))
  		goto dput_and_out;
  
  	set_fs_root(current->fs, nd.mnt, nd.dentry);
  	set_fs_altroot();
  	error = 0;
  dput_and_out:
  	path_release(&nd);
  out:
  	return error;
  }
  
  asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
  {
  	struct inode * inode;
  	struct dentry * dentry;
  	struct file * file;
  	int err = -EBADF;
  	struct iattr newattrs;
  
  	file = fget(fd);
  	if (!file)
  		goto out;

  	dentry = file->f_path.dentry;

  	inode = dentry->d_inode;

  	audit_inode(NULL, inode);

  	err = -EROFS;
  	if (IS_RDONLY(inode))
  		goto out_putf;
  	err = -EPERM;
  	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  		goto out_putf;

  	mutex_lock(&inode->i_mutex);

  	if (mode == (mode_t) -1)
  		mode = inode->i_mode;
  	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
  	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
  	err = notify_change(dentry, &newattrs);

  	mutex_unlock(&inode->i_mutex);

  
  out_putf:
  	fput(file);
  out:
  	return err;
  }

  asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
  			     mode_t mode)

  {
  	struct nameidata nd;
  	struct inode * inode;
  	int error;
  	struct iattr newattrs;

  	error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);

  	if (error)
  		goto out;
  	inode = nd.dentry->d_inode;
  
  	error = -EROFS;
  	if (IS_RDONLY(inode))
  		goto dput_and_out;
  
  	error = -EPERM;
  	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  		goto dput_and_out;

  	mutex_lock(&inode->i_mutex);

  	if (mode == (mode_t) -1)
  		mode = inode->i_mode;
  	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
  	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
  	error = notify_change(nd.dentry, &newattrs);

  	mutex_unlock(&inode->i_mutex);

  
  dput_and_out:
  	path_release(&nd);
  out:
  	return error;
  }

  asmlinkage long sys_chmod(const char __user *filename, mode_t mode)
  {
  	return sys_fchmodat(AT_FDCWD, filename, mode);
  }

  static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
  {
  	struct inode * inode;
  	int error;
  	struct iattr newattrs;
  
  	error = -ENOENT;
  	if (!(inode = dentry->d_inode)) {
  		printk(KERN_ERR "chown_common: NULL inode
  ");
  		goto out;
  	}
  	error = -EROFS;
  	if (IS_RDONLY(inode))
  		goto out;
  	error = -EPERM;
  	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
  		goto out;
  	newattrs.ia_valid =  ATTR_CTIME;
  	if (user != (uid_t) -1) {
  		newattrs.ia_valid |= ATTR_UID;
  		newattrs.ia_uid = user;
  	}
  	if (group != (gid_t) -1) {
  		newattrs.ia_valid |= ATTR_GID;
  		newattrs.ia_gid = group;
  	}
  	if (!S_ISDIR(inode->i_mode))
  		newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID;

  	mutex_lock(&inode->i_mutex);

  	error = notify_change(dentry, &newattrs);

  	mutex_unlock(&inode->i_mutex);

  out:
  	return error;
  }
  
  asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
  {
  	struct nameidata nd;
  	int error;
  
  	error = user_path_walk(filename, &nd);

  	if (error)
  		goto out;
  	error = chown_common(nd.dentry, user, group);
  	path_release(&nd);
  out:

  	return error;
  }

  asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
  			     gid_t group, int flag)
  {
  	struct nameidata nd;
  	int error = -EINVAL;
  	int follow;
  
  	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
  		goto out;
  
  	follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
  	error = __user_walk_fd(dfd, filename, follow, &nd);

  	if (error)
  		goto out;
  	error = chown_common(nd.dentry, user, group);
  	path_release(&nd);

  out:
  	return error;
  }

  asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
  {
  	struct nameidata nd;
  	int error;
  
  	error = user_path_walk_link(filename, &nd);

  	if (error)
  		goto out;
  	error = chown_common(nd.dentry, user, group);
  	path_release(&nd);
  out:

  	return error;
  }
  
  
  asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
  {
  	struct file * file;
  	int error = -EBADF;

  	struct dentry * dentry;

  
  	file = fget(fd);

  	if (!file)
  		goto out;

  	dentry = file->f_path.dentry;

  	audit_inode(NULL, dentry->d_inode);
  	error = chown_common(dentry, user, group);
  	fput(file);
  out:

  	return error;
  }

  static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,

  					int flags, struct file *f,
  					int (*open)(struct inode *, struct file *))

  {

  	struct inode *inode;
  	int error;

  	f->f_flags = flags;

  	f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
  				FMODE_PREAD | FMODE_PWRITE;

  	inode = dentry->d_inode;
  	if (f->f_mode & FMODE_WRITE) {
  		error = get_write_access(inode);
  		if (error)
  			goto cleanup_file;
  	}
  
  	f->f_mapping = inode->i_mapping;

  	f->f_path.dentry = dentry;
  	f->f_path.mnt = mnt;

  	f->f_pos = 0;
  	f->f_op = fops_get(inode->i_fop);
  	file_move(f, &inode->i_sb->s_files);

  	if (!open && f->f_op)
  		open = f->f_op->open;
  	if (open) {
  		error = open(inode, f);

  		if (error)
  			goto cleanup_all;
  	}

  	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
  
  	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
  
  	/* NB: we're sure to have correct a_ops only after f_op->open */
  	if (f->f_flags & O_DIRECT) {

  		if (!f->f_mapping->a_ops ||
  		    ((!f->f_mapping->a_ops->direct_IO) &&
  		    (!f->f_mapping->a_ops->get_xip_page))) {

  			fput(f);
  			f = ERR_PTR(-EINVAL);
  		}
  	}
  
  	return f;
  
  cleanup_all:
  	fops_put(f->f_op);
  	if (f->f_mode & FMODE_WRITE)
  		put_write_access(inode);
  	file_kill(f);

  	f->f_path.dentry = NULL;
  	f->f_path.mnt = NULL;

  cleanup_file:
  	put_filp(f);

  	dput(dentry);
  	mntput(mnt);
  	return ERR_PTR(error);
  }

  /*
   * Note that while the flag value (low two bits) for sys_open means:
   *	00 - read-only
   *	01 - write-only
   *	10 - read-write
   *	11 - special
   * it is changed into
   *	00 - no permissions needed
   *	01 - read-permission
   *	10 - write-permission
   *	11 - read-write
   * for the internal routines (ie open_namei()/follow_link() etc). 00 is
   * used by symlinks.
   */

  static struct file *do_filp_open(int dfd, const char *filename, int flags,
  				 int mode)

  {
  	int namei_flags, error;
  	struct nameidata nd;

  
  	namei_flags = flags;
  	if ((namei_flags+1) & O_ACCMODE)
  		namei_flags++;

  	error = open_namei(dfd, filename, namei_flags, mode, &nd);

  	if (!error)

  		return nameidata_to_filp(&nd, flags);

  	return ERR_PTR(error);
  }

  
  struct file *filp_open(const char *filename, int flags, int mode)
  {
  	return do_filp_open(AT_FDCWD, filename, flags, mode);
  }

  EXPORT_SYMBOL(filp_open);

  /**
   * lookup_instantiate_filp - instantiates the open intent filp
   * @nd: pointer to nameidata
   * @dentry: pointer to dentry
   * @open: open callback
   *
   * Helper for filesystems that want to use lookup open intents and pass back
   * a fully instantiated struct file to the caller.
   * This function is meant to be called from within a filesystem's
   * lookup method.

   * Beware of calling it for non-regular files! Those ->open methods might block
   * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
   * leading to a deadlock, as nobody can open that fifo anymore, because
   * another process to open fifo will block on locked parent when doing lookup).

   * Note that in case of error, nd->intent.open.file is destroyed, but the
   * path information remains valid.
   * If the open callback is set to NULL, then the standard f_op->open()
   * filesystem callback is substituted.
   */
  struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
  		int (*open)(struct inode *, struct file *))
  {
  	if (IS_ERR(nd->intent.open.file))
  		goto out;
  	if (IS_ERR(dentry))
  		goto out_err;
  	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
  					     nd->intent.open.flags - 1,
  					     nd->intent.open.file,
  					     open);
  out:
  	return nd->intent.open.file;
  out_err:
  	release_open_intent(nd);
  	nd->intent.open.file = (struct file *)dentry;
  	goto out;
  }
  EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
  
  /**
   * nameidata_to_filp - convert a nameidata to an open filp.
   * @nd: pointer to nameidata
   * @flags: open flags
   *
   * Note that this function destroys the original nameidata
   */
  struct file *nameidata_to_filp(struct nameidata *nd, int flags)
  {
  	struct file *filp;
  
  	/* Pick up the filp from the open intent */
  	filp = nd->intent.open.file;
  	/* Has the filesystem initialised the file for us? */

  	if (filp->f_path.dentry == NULL)

  		filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
  	else
  		path_release(nd);
  	return filp;
  }

  /*
   * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
   * error.
   */

  struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
  {
  	int error;
  	struct file *f;
  
  	error = -ENFILE;
  	f = get_empty_filp();

  	if (f == NULL) {
  		dput(dentry);
  		mntput(mnt);

  		return ERR_PTR(error);

  	}

  	return __dentry_open(dentry, mnt, flags, f, NULL);

  }

  EXPORT_SYMBOL(dentry_open);
  
  /*
   * Find an empty file descriptor entry, and mark it busy.
   */

  int get_unused_fd_flags(int flags)

  {
  	struct files_struct * files = current->files;
  	int fd, error;

  	struct fdtable *fdt;

  
    	error = -EMFILE;
  	spin_lock(&files->file_lock);
  
  repeat:

  	fdt = files_fdtable(files);

  	fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,

  				files->next_fd);

  
  	/*
  	 * N.B. For clone tasks sharing a files structure, this test
  	 * will limit the total number of files that can be opened.
  	 */
  	if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
  		goto out;
  
  	/* Do we need to expand the fd array or fd set?  */
  	error = expand_files(files, fd);
  	if (error < 0)
  		goto out;
  
  	if (error) {
  		/*
  	 	 * If we needed to expand the fs array we
  		 * might have blocked - try again.
  		 */
  		error = -EMFILE;
  		goto repeat;
  	}

  	FD_SET(fd, fdt->open_fds);

  	if (flags & O_CLOEXEC)
  		FD_SET(fd, fdt->close_on_exec);
  	else
  		FD_CLR(fd, fdt->close_on_exec);

  	files->next_fd = fd + 1;

  #if 1
  	/* Sanity check */

  	if (fdt->fd[fd] != NULL) {

  		printk(KERN_WARNING "get_unused_fd: slot %d not NULL!
  ", fd);

  		fdt->fd[fd] = NULL;

  	}
  #endif
  	error = fd;
  
  out:
  	spin_unlock(&files->file_lock);
  	return error;
  }

  int get_unused_fd(void)
  {
  	return get_unused_fd_flags(0);
  }

  EXPORT_SYMBOL(get_unused_fd);

  static void __put_unused_fd(struct files_struct *files, unsigned int fd)

  {

  	struct fdtable *fdt = files_fdtable(files);
  	__FD_CLR(fd, fdt->open_fds);

  	if (fd < files->next_fd)
  		files->next_fd = fd;

  }
  
  void fastcall put_unused_fd(unsigned int fd)
  {
  	struct files_struct *files = current->files;
  	spin_lock(&files->file_lock);
  	__put_unused_fd(files, fd);
  	spin_unlock(&files->file_lock);
  }
  
  EXPORT_SYMBOL(put_unused_fd);
  
  /*

   * Install a file pointer in the fd array.

   *
   * The VFS is full of places where we drop the files lock between
   * setting the open_fds bitmap and installing the file in the file
   * array.  At any such point, we are vulnerable to a dup2() race
   * installing a file in the array before us.  We need to detect this and
   * fput() the struct file we are about to overwrite in this case.
   *
   * It should never happen - if we allow dup2() do it, _really_ bad things
   * will follow.
   */
  
  void fastcall fd_install(unsigned int fd, struct file * file)
  {
  	struct files_struct *files = current->files;

  	struct fdtable *fdt;

  	spin_lock(&files->file_lock);

  	fdt = files_fdtable(files);

  	BUG_ON(fdt->fd[fd] != NULL);
  	rcu_assign_pointer(fdt->fd[fd], file);

  	spin_unlock(&files->file_lock);
  }
  
  EXPORT_SYMBOL(fd_install);

  long do_sys_open(int dfd, const char __user *filename, int flags, int mode)

  {

  	char *tmp = getname(filename);
  	int fd = PTR_ERR(tmp);

  	if (!IS_ERR(tmp)) {

  		fd = get_unused_fd_flags(flags);

  		if (fd >= 0) {

  			struct file *f = do_filp_open(dfd, tmp, flags, mode);

  			if (IS_ERR(f)) {
  				put_unused_fd(fd);
  				fd = PTR_ERR(f);
  			} else {

  				fsnotify_open(f->f_path.dentry);

  				fd_install(fd, f);
  			}

  		}

  		putname(tmp);
  	}
  	return fd;

  }

  
  asmlinkage long sys_open(const char __user *filename, int flags, int mode)
  {

  	long ret;

  	if (force_o_largefile())
  		flags |= O_LARGEFILE;

  	ret = do_sys_open(AT_FDCWD, filename, flags, mode);
  	/* avoid REGPARM breakage on x86: */
  	prevent_tail_call(ret);
  	return ret;

  }

  EXPORT_SYMBOL_GPL(sys_open);

  asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
  			   int mode)
  {

  	long ret;

  	if (force_o_largefile())
  		flags |= O_LARGEFILE;

  	ret = do_sys_open(dfd, filename, flags, mode);
  	/* avoid REGPARM breakage on x86: */
  	prevent_tail_call(ret);
  	return ret;

  }

  #ifndef __alpha__
  
  /*
   * For backward compatibility?  Maybe this should be moved
   * into arch/i386 instead?
   */
  asmlinkage long sys_creat(const char __user * pathname, int mode)
  {
  	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
  }
  
  #endif
  
  /*
   * "id" is the POSIX thread ID. We use the
   * files pointer for this..
   */
  int filp_close(struct file *filp, fl_owner_t id)
  {

  	int retval = 0;

  
  	if (!file_count(filp)) {
  		printk(KERN_ERR "VFS: Close: file count is 0
  ");

  		return 0;

  	}

  	if (filp->f_op && filp->f_op->flush)

  		retval = filp->f_op->flush(filp, id);

  
  	dnotify_flush(filp, id);
  	locks_remove_posix(filp, id);
  	fput(filp);
  	return retval;
  }
  
  EXPORT_SYMBOL(filp_close);
  
  /*
   * Careful here! We test whether the file pointer is NULL before
   * releasing the fd. This ensures that one clone task can't release
   * an fd while another clone is opening it.
   */
  asmlinkage long sys_close(unsigned int fd)
  {
  	struct file * filp;
  	struct files_struct *files = current->files;

  	struct fdtable *fdt;

  	int retval;

  
  	spin_lock(&files->file_lock);

  	fdt = files_fdtable(files);
  	if (fd >= fdt->max_fds)

  		goto out_unlock;

  	filp = fdt->fd[fd];

  	if (!filp)
  		goto out_unlock;

  	rcu_assign_pointer(fdt->fd[fd], NULL);

  	FD_CLR(fd, fdt->close_on_exec);

  	__put_unused_fd(files, fd);
  	spin_unlock(&files->file_lock);

  	retval = filp_close(filp, files);
  
  	/* can't restart close syscall because file table entry was cleared */
  	if (unlikely(retval == -ERESTARTSYS ||
  		     retval == -ERESTARTNOINTR ||
  		     retval == -ERESTARTNOHAND ||
  		     retval == -ERESTART_RESTARTBLOCK))
  		retval = -EINTR;
  
  	return retval;

  
  out_unlock:
  	spin_unlock(&files->file_lock);
  	return -EBADF;
  }
  
  EXPORT_SYMBOL(sys_close);
  
  /*
   * This routine simulates a hangup on the tty, to arrange that users
   * are given clean terminals at login time.
   */
  asmlinkage long sys_vhangup(void)
  {
  	if (capable(CAP_SYS_TTY_CONFIG)) {

  		/* XXX: this needs locking */

  		tty_vhangup(current->signal->tty);
  		return 0;
  	}
  	return -EPERM;
  }
  
  /*
   * Called when an inode is about to be open.
   * We use this to disallow opening large files on 32bit systems if
   * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
   * on this flag in sys_open.
   */
  int generic_file_open(struct inode * inode, struct file * filp)
  {
  	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
  		return -EFBIG;
  	return 0;
  }
  
  EXPORT_SYMBOL(generic_file_open);
  
  /*
   * This is used by subsystems that don't want seekable
   * file descriptors
   */
  int nonseekable_open(struct inode *inode, struct file *filp)
  {
  	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
  	return 0;
  }
  
  EXPORT_SYMBOL(nonseekable_open);