/*
   *   fs/cifs/readdir.c
   *
   *   Directory search handling

   *

   *   Copyright (C) International Business Machines  Corp., 2004, 2008

   *   Copyright (C) Red Hat, Inc., 2011

   *   Author(s): Steve French (sfrench@us.ibm.com)
   *
   *   This library is free software; you can redistribute it and/or modify
   *   it under the terms of the GNU Lesser General Public License as published
   *   by the Free Software Foundation; either version 2.1 of the License, or
   *   (at your option) any later version.
   *
   *   This library is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
   *   the GNU Lesser General Public License for more details.
   *
   *   You should have received a copy of the GNU Lesser General Public License
   *   along with this library; if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  #include <linux/fs.h>

  #include <linux/pagemap.h>

  #include <linux/slab.h>

  #include <linux/stat.h>

  #include "cifspdu.h"
  #include "cifsglob.h"
  #include "cifsproto.h"
  #include "cifs_unicode.h"
  #include "cifs_debug.h"
  #include "cifs_fs_sb.h"
  #include "cifsfs.h"

  #include "smb2proto.h"

  /*
   * To be safe - for UCS to UTF-8 with strings loaded with the rare long
   * characters alloc more to account for such multibyte target UTF-8
   * characters.
   */
  #define UNICODE_NAME_MAX ((4 * NAME_MAX) + 2)

  #ifdef CONFIG_CIFS_DEBUG2
  static void dump_cifs_file_struct(struct file *file, char *label)

  {

  	struct cifsFileInfo *cf;

  	if (file) {

  		cf = file->private_data;

  		if (cf == NULL) {

  			cifs_dbg(FYI, "empty cifs private file data
  ");

  			return;
  		}

  		if (cf->invalidHandle)

  			cifs_dbg(FYI, "Invalid handle
  ");

  		if (cf->srch_inf.endOfSearch)

  			cifs_dbg(FYI, "end of search
  ");

  		if (cf->srch_inf.emptyDir)

  			cifs_dbg(FYI, "empty dir
  ");

  	}

  }

  #else
  static inline void dump_cifs_file_struct(struct file *file, char *label)
  {
  }

  #endif /* DEBUG2 */

  /*

   * Attempt to preload the dcache with the results from the FIND_FIRST/NEXT
   *

   * Find the dentry that matches "name". If there isn't one, create one. If it's

   * a negative dentry or the uniqueid or filetype(mode) changed,
   * then drop it and recreate it.

   */

  static void
  cifs_prime_dcache(struct dentry *parent, struct qstr *name,

  		    struct cifs_fattr *fattr)
  {
  	struct dentry *dentry, *alias;
  	struct inode *inode;

  	struct super_block *sb = parent->d_sb;

  	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);

  	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

  	cifs_dbg(FYI, "%s: for %s
  ", __func__, name->name);

  	dentry = d_hash_and_lookup(parent, name);

  	if (!dentry) {
  		/*
  		 * If we know that the inode will need to be revalidated
  		 * immediately, then don't create a new dentry for it.
  		 * We'll end up doing an on the wire call either way and
  		 * this spares us an invalidation.
  		 */
  		if (fattr->cf_flags & CIFS_FATTR_NEED_REVAL)
  			return;
  retry:
  		dentry = d_alloc_parallel(parent, name, &wq);
  	}

  	if (IS_ERR(dentry))

  		return;

  	if (!d_in_lookup(dentry)) {

  		inode = d_inode(dentry);

  		if (inode) {

  			if (d_mountpoint(dentry)) {
  				dput(dentry);
  				return;
  			}

  			/*
  			 * If we're generating inode numbers, then we don't
  			 * want to clobber the existing one with the one that
  			 * the readdir code created.
  			 */
  			if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM))
  				fattr->cf_uniqueid = CIFS_I(inode)->uniqueid;

  			/* update inode in place
  			 * if both i_ino and i_mode didn't change */
  			if (CIFS_I(inode)->uniqueid == fattr->cf_uniqueid &&
  			    (inode->i_mode & S_IFMT) ==
  			    (fattr->cf_mode & S_IFMT)) {

  				cifs_fattr_to_inode(inode, fattr);

  				dput(dentry);
  				return;

  			}

  		}

  		d_invalidate(dentry);

  		dput(dentry);

  		goto retry;
  	} else {
  		inode = cifs_iget(sb, fattr);
  		if (!inode)
  			inode = ERR_PTR(-ENOMEM);
  		alias = d_splice_alias(inode, dentry);
  		d_lookup_done(dentry);
  		if (alias && !IS_ERR(alias))
  			dput(alias);

  	}

  	dput(dentry);

  }

  static bool reparse_file_needs_reval(const struct cifs_fattr *fattr)
  {
  	if (!(fattr->cf_cifsattrs & ATTR_REPARSE))
  		return false;
  	/*
  	 * The DFS tags should be only intepreted by server side as per
  	 * MS-FSCC 2.1.2.1, but let's include them anyway.
  	 *
  	 * Besides, if cf_cifstag is unset (0), then we still need it to be
  	 * revalidated to know exactly what reparse point it is.
  	 */
  	switch (fattr->cf_cifstag) {
  	case IO_REPARSE_TAG_DFS:
  	case IO_REPARSE_TAG_DFSR:
  	case IO_REPARSE_TAG_SYMLINK:
  	case IO_REPARSE_TAG_NFS:
  	case 0:
  		return true;
  	}
  	return false;
  }

  static void
  cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)

  {

  	fattr->cf_uid = cifs_sb->mnt_uid;
  	fattr->cf_gid = cifs_sb->mnt_gid;

  	/*
  	 * The IO_REPARSE_TAG_LX_ tags originally were used by WSL but they
  	 * are preferred by the Linux client in some cases since, unlike
  	 * the NFS reparse tag (or EAs), they don't require an extra query
  	 * to determine which type of special file they represent.
  	 * TODO: go through all documented  reparse tags to see if we can
  	 * reasonably map some of them to directories vs. files vs. symlinks
  	 */

  	if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
  		fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
  		fattr->cf_dtype = DT_DIR;

  	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_SYMLINK) {
  		fattr->cf_mode |= S_IFLNK | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_LNK;
  	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_FIFO) {
  		fattr->cf_mode |= S_IFIFO | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_FIFO;
  	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_AF_UNIX) {
  		fattr->cf_mode |= S_IFSOCK | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_SOCK;
  	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_CHR) {
  		fattr->cf_mode |= S_IFCHR | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_CHR;
  	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_BLK) {
  		fattr->cf_mode |= S_IFBLK | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_BLK;
  	} else { /* TODO: should we mark some other reparse points (like DFSR) as directories? */

  		fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
  		fattr->cf_dtype = DT_REG;

  	}

  	/*
  	 * We need to revalidate it further to make a decision about whether it
  	 * is a symbolic link, DFS referral or a reparse point with a direct
  	 * access like junctions, deduplicated files, NFS symlinks.
  	 */

  	if (reparse_file_needs_reval(fattr))

  		fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;

  	/* non-unix readdir doesn't provide nlink */
  	fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;

  	if (fattr->cf_cifsattrs & ATTR_READONLY)
  		fattr->cf_mode &= ~S_IWUGO;

  	/*
  	 * We of course don't get ACL info in FIND_FIRST/NEXT results, so
  	 * mark it for revalidation so that "ls -l" will look right. It might
  	 * be super-slow, but if we don't do this then the ownership of files
  	 * may look wrong since the inodes may not have timed out by the time
  	 * "ls" does a stat() call on them.
  	 */

  	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) ||
  	    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MODE_FROM_SID))

  		fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;

  	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL &&
  	    fattr->cf_cifsattrs & ATTR_SYSTEM) {
  		if (fattr->cf_eof == 0)  {
  			fattr->cf_mode &= ~S_IFMT;
  			fattr->cf_mode |= S_IFIFO;
  			fattr->cf_dtype = DT_FIFO;

  		} else {

  			/*

  			 * trying to get the type and mode via SFU can be slow,
  			 * so just call those regular files for now, and mark
  			 * for reval

  			 */

  			fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;

  		}
  	}

  }

  /* Fill a cifs_fattr struct with info from SMB_FIND_FILE_POSIX_INFO. */
  static void
  cifs_posix_to_fattr(struct cifs_fattr *fattr, struct smb2_posix_info *info,
  		    struct cifs_sb_info *cifs_sb)
  {
  	struct smb2_posix_info_parsed parsed;
  
  	posix_info_parse(info, NULL, &parsed);
  
  	memset(fattr, 0, sizeof(*fattr));
  	fattr->cf_uniqueid = le64_to_cpu(info->Inode);
  	fattr->cf_bytes = le64_to_cpu(info->AllocationSize);
  	fattr->cf_eof = le64_to_cpu(info->EndOfFile);
  
  	fattr->cf_atime = cifs_NTtimeToUnix(info->LastAccessTime);
  	fattr->cf_mtime = cifs_NTtimeToUnix(info->LastWriteTime);
  	fattr->cf_ctime = cifs_NTtimeToUnix(info->CreationTime);
  
  	fattr->cf_nlink = le32_to_cpu(info->HardLinks);
  	fattr->cf_cifsattrs = le32_to_cpu(info->DosAttributes);
  
  	/*
  	 * Since we set the inode type below we need to mask off
  	 * to avoid strange results if bits set above.
  	 * XXX: why not make server&client use the type bits?
  	 */
  	fattr->cf_mode = le32_to_cpu(info->Mode) & ~S_IFMT;

  	cifs_dbg(FYI, "posix fattr: dev %d, reparse %d, mode %o
  ",

  		 le32_to_cpu(info->DeviceId),
  		 le32_to_cpu(info->ReparseTag),
  		 le32_to_cpu(info->Mode));
  
  	if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
  		fattr->cf_mode |= S_IFDIR;
  		fattr->cf_dtype = DT_DIR;
  	} else {
  		/*
  		 * mark anything that is not a dir as regular
  		 * file. special files should have the REPARSE
  		 * attribute and will be marked as needing revaluation
  		 */
  		fattr->cf_mode |= S_IFREG;
  		fattr->cf_dtype = DT_REG;
  	}
  
  	if (reparse_file_needs_reval(fattr))
  		fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;

  	sid_to_id(cifs_sb, &parsed.owner, fattr, SIDOWNER);
  	sid_to_id(cifs_sb, &parsed.group, fattr, SIDGROUP);

  }

  static void __dir_info_to_fattr(struct cifs_fattr *fattr, const void *info)
  {
  	const FILE_DIRECTORY_INFO *fi = info;
  
  	memset(fattr, 0, sizeof(*fattr));
  	fattr->cf_cifsattrs = le32_to_cpu(fi->ExtFileAttributes);
  	fattr->cf_eof = le64_to_cpu(fi->EndOfFile);
  	fattr->cf_bytes = le64_to_cpu(fi->AllocationSize);
  	fattr->cf_createtime = le64_to_cpu(fi->CreationTime);
  	fattr->cf_atime = cifs_NTtimeToUnix(fi->LastAccessTime);
  	fattr->cf_ctime = cifs_NTtimeToUnix(fi->ChangeTime);
  	fattr->cf_mtime = cifs_NTtimeToUnix(fi->LastWriteTime);
  }

  void

  cifs_dir_info_to_fattr(struct cifs_fattr *fattr, FILE_DIRECTORY_INFO *info,
  		       struct cifs_sb_info *cifs_sb)
  {

  	__dir_info_to_fattr(fattr, info);
  	cifs_fill_common_info(fattr, cifs_sb);
  }

  static void cifs_fulldir_info_to_fattr(struct cifs_fattr *fattr,
  				       SEARCH_ID_FULL_DIR_INFO *info,
  				       struct cifs_sb_info *cifs_sb)
  {
  	__dir_info_to_fattr(fattr, info);
  
  	/* See MS-FSCC 2.4.18 FileIdFullDirectoryInformation */
  	if (fattr->cf_cifsattrs & ATTR_REPARSE)
  		fattr->cf_cifstag = le32_to_cpu(info->EaSize);

  	cifs_fill_common_info(fattr, cifs_sb);
  }

  static void

  cifs_std_info_to_fattr(struct cifs_fattr *fattr, FIND_FILE_STANDARD_INFO *info,
  		       struct cifs_sb_info *cifs_sb)
  {

  	int offset = cifs_sb_master_tcon(cifs_sb)->ses->server->timeAdj;

  	memset(fattr, 0, sizeof(*fattr));
  	fattr->cf_atime = cnvrtDosUnixTm(info->LastAccessDate,
  					    info->LastAccessTime, offset);
  	fattr->cf_ctime = cnvrtDosUnixTm(info->LastWriteDate,
  					    info->LastWriteTime, offset);
  	fattr->cf_mtime = cnvrtDosUnixTm(info->LastWriteDate,
  					    info->LastWriteTime, offset);
  
  	fattr->cf_cifsattrs = le16_to_cpu(info->Attributes);
  	fattr->cf_bytes = le32_to_cpu(info->AllocationSize);
  	fattr->cf_eof = le32_to_cpu(info->DataSize);
  
  	cifs_fill_common_info(fattr, cifs_sb);

  }

  /* BB eventually need to add the following helper function to
        resolve NT_STATUS_STOPPED_ON_SYMLINK return code when
        we try to do FindFirst on (NTFS) directory symlinks */
  /*
  int get_symlink_reparse_path(char *full_path, struct cifs_sb_info *cifs_sb,

  			     unsigned int xid)

  {
  	__u16 fid;
  	int len;
  	int oplock = 0;
  	int rc;

  	struct cifs_tcon *ptcon = cifs_sb_tcon(cifs_sb);

  	char *tmpbuffer;
  
  	rc = CIFSSMBOpen(xid, ptcon, full_path, FILE_OPEN, GENERIC_READ,
  			OPEN_REPARSE_POINT, &fid, &oplock, NULL,
  			cifs_sb->local_nls,

  			cifs_remap(cifs_sb);

  	if (!rc) {
  		tmpbuffer = kmalloc(maxpath);
  		rc = CIFSSMBQueryReparseLinkInfo(xid, ptcon, full_path,
  				tmpbuffer,
  				maxpath -1,
  				fid,
  				cifs_sb->local_nls);
  		if (CIFSSMBClose(xid, ptcon, fid)) {

  			cifs_dbg(FYI, "Error closing temporary reparsepoint open
  ");

  		}
  	}
  }
   */

  static int

  initiate_cifs_search(const unsigned int xid, struct file *file,
  		     char *full_path)

  {

  	__u16 search_flags;

  	int rc = 0;

  	struct cifsFileInfo *cifsFile;

  	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);

  	struct tcon_link *tlink = NULL;

  	struct cifs_tcon *tcon;

  	struct TCP_Server_Info *server;

  	if (file->private_data == NULL) {

  		tlink = cifs_sb_tlink(cifs_sb);
  		if (IS_ERR(tlink))
  			return PTR_ERR(tlink);
  
  		cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
  		if (cifsFile == NULL) {
  			rc = -ENOMEM;
  			goto error_exit;
  		}

  		spin_lock_init(&cifsFile->file_info_lock);

  		file->private_data = cifsFile;
  		cifsFile->tlink = cifs_get_tlink(tlink);

  		tcon = tlink_tcon(tlink);

  	} else {
  		cifsFile = file->private_data;

  		tcon = tlink_tcon(cifsFile->tlink);

  	}

  	server = tcon->ses->server;
  
  	if (!server->ops->query_dir_first) {
  		rc = -ENOSYS;
  		goto error_exit;
  	}

  	cifsFile->invalidHandle = true;
  	cifsFile->srch_inf.endOfSearch = false;

  	cifs_dbg(FYI, "Full path: %s start at: %lld
  ", full_path, file->f_pos);

  ffirst_retry:

  	/* test for Unix extensions */

  	/* but now check for them on the share/mount not on the SMB session */

  	/* if (cap_unix(tcon->ses) { */
  	if (tcon->unix_ext)

  		cifsFile->srch_inf.info_level = SMB_FIND_FILE_UNIX;

  	else if (tcon->posix_extensions)
  		cifsFile->srch_inf.info_level = SMB_FIND_FILE_POSIX_INFO;

  	else if ((tcon->ses->capabilities &
  		  tcon->ses->server->vals->cap_nt_find) == 0) {

  		cifsFile->srch_inf.info_level = SMB_FIND_FILE_INFO_STANDARD;

  	} else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
  		cifsFile->srch_inf.info_level = SMB_FIND_FILE_ID_FULL_DIR_INFO;
  	} else /* not srvinos - BB fixme add check for backlevel? */ {
  		cifsFile->srch_inf.info_level = SMB_FIND_FILE_DIRECTORY_INFO;
  	}

  	search_flags = CIFS_SEARCH_CLOSE_AT_END | CIFS_SEARCH_RETURN_RESUME;
  	if (backup_cred(cifs_sb))
  		search_flags |= CIFS_SEARCH_BACKUP_SEARCH;

  	rc = server->ops->query_dir_first(xid, tcon, full_path, cifs_sb,
  					  &cifsFile->fid, search_flags,
  					  &cifsFile->srch_inf);

  	if (rc == 0)

  		cifsFile->invalidHandle = false;

  	/* BB add following call to handle readdir on new NTFS symlink errors

  	else if STATUS_STOPPED_ON_SYMLINK
  		call get_symlink_reparse_path and retry with new path */
  	else if ((rc == -EOPNOTSUPP) &&

  		(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
  		cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
  		goto ffirst_retry;
  	}

  error_exit:

  	cifs_put_tlink(tlink);

  	return rc;
  }
  
  /* return length of unicode string in bytes */

  static int cifs_unicode_bytelen(const char *str)

  {
  	int len;

  	const __le16 *ustr = (const __le16 *)str;

  	for (len = 0; len <= PATH_MAX; len++) {

  		if (ustr[len] == 0)

  			return len << 1;
  	}

  	cifs_dbg(FYI, "Unicode string longer than PATH_MAX found
  ");

  	return len << 1;
  }

  static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)

  {

  	char *new_entry;

  	FILE_DIRECTORY_INFO *pDirInfo = (FILE_DIRECTORY_INFO *)old_entry;

  	if (level == SMB_FIND_FILE_INFO_STANDARD) {

  		FIND_FILE_STANDARD_INFO *pfData;

  		pfData = (FIND_FILE_STANDARD_INFO *)pDirInfo;
  
  		new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) +
  				pfData->FileNameLength;

  	} else {
  		u32 next_offset = le32_to_cpu(pDirInfo->NextEntryOffset);
  
  		if (old_entry + next_offset < old_entry) {

  			cifs_dbg(VFS, "Invalid offset %u
  ", next_offset);

  			return NULL;
  		}
  		new_entry = old_entry + next_offset;
  	}

  	cifs_dbg(FYI, "new entry %p old entry %p
  ", new_entry, old_entry);

  	/* validate that new_entry is not past end of SMB */

  	if (new_entry >= end_of_smb) {

  		cifs_dbg(VFS, "search entry %p began after end of SMB %p old entry %p
  ",
  			 new_entry, end_of_smb, old_entry);

  		return NULL;

  	} else if (((level == SMB_FIND_FILE_INFO_STANDARD) &&

  		    (new_entry + sizeof(FIND_FILE_STANDARD_INFO) > end_of_smb))
  		  || ((level != SMB_FIND_FILE_INFO_STANDARD) &&

  		   (new_entry + sizeof(FILE_DIRECTORY_INFO) > end_of_smb)))  {

  		cifs_dbg(VFS, "search entry %p extends after end of SMB %p
  ",
  			 new_entry, end_of_smb);

  		return NULL;

  	} else

  		return new_entry;
  
  }

  struct cifs_dirent {
  	const char	*name;
  	size_t		namelen;
  	u32		resume_key;
  	u64		ino;
  };

  static void cifs_fill_dirent_posix(struct cifs_dirent *de,
  				   const struct smb2_posix_info *info)
  {
  	struct smb2_posix_info_parsed parsed;
  
  	/* payload should have already been checked at this point */
  	if (posix_info_parse(info, NULL, &parsed) < 0) {

  		cifs_dbg(VFS, "Invalid POSIX info payload
  ");

  		return;
  	}
  
  	de->name = parsed.name;
  	de->namelen = parsed.name_len;
  	de->resume_key = info->Ignored;
  	de->ino = le64_to_cpu(info->Inode);
  }

  static void cifs_fill_dirent_unix(struct cifs_dirent *de,
  		const FILE_UNIX_INFO *info, bool is_unicode)
  {
  	de->name = &info->FileName[0];
  	if (is_unicode)
  		de->namelen = cifs_unicode_bytelen(de->name);
  	else
  		de->namelen = strnlen(de->name, PATH_MAX);
  	de->resume_key = info->ResumeKey;
  	de->ino = le64_to_cpu(info->basic.UniqueId);
  }
  
  static void cifs_fill_dirent_dir(struct cifs_dirent *de,
  		const FILE_DIRECTORY_INFO *info)
  {
  	de->name = &info->FileName[0];
  	de->namelen = le32_to_cpu(info->FileNameLength);
  	de->resume_key = info->FileIndex;
  }
  
  static void cifs_fill_dirent_full(struct cifs_dirent *de,
  		const FILE_FULL_DIRECTORY_INFO *info)
  {
  	de->name = &info->FileName[0];
  	de->namelen = le32_to_cpu(info->FileNameLength);
  	de->resume_key = info->FileIndex;
  }
  
  static void cifs_fill_dirent_search(struct cifs_dirent *de,
  		const SEARCH_ID_FULL_DIR_INFO *info)
  {
  	de->name = &info->FileName[0];
  	de->namelen = le32_to_cpu(info->FileNameLength);
  	de->resume_key = info->FileIndex;
  	de->ino = le64_to_cpu(info->UniqueId);
  }
  
  static void cifs_fill_dirent_both(struct cifs_dirent *de,
  		const FILE_BOTH_DIRECTORY_INFO *info)
  {
  	de->name = &info->FileName[0];
  	de->namelen = le32_to_cpu(info->FileNameLength);
  	de->resume_key = info->FileIndex;
  }
  
  static void cifs_fill_dirent_std(struct cifs_dirent *de,
  		const FIND_FILE_STANDARD_INFO *info)
  {
  	de->name = &info->FileName[0];
  	/* one byte length, no endianess conversion */
  	de->namelen = info->FileNameLength;
  	de->resume_key = info->ResumeKey;
  }
  
  static int cifs_fill_dirent(struct cifs_dirent *de, const void *info,
  		u16 level, bool is_unicode)
  {
  	memset(de, 0, sizeof(*de));
  
  	switch (level) {

  	case SMB_FIND_FILE_POSIX_INFO:
  		cifs_fill_dirent_posix(de, info);
  		break;

  	case SMB_FIND_FILE_UNIX:
  		cifs_fill_dirent_unix(de, info, is_unicode);
  		break;
  	case SMB_FIND_FILE_DIRECTORY_INFO:
  		cifs_fill_dirent_dir(de, info);
  		break;
  	case SMB_FIND_FILE_FULL_DIRECTORY_INFO:
  		cifs_fill_dirent_full(de, info);
  		break;
  	case SMB_FIND_FILE_ID_FULL_DIR_INFO:
  		cifs_fill_dirent_search(de, info);
  		break;
  	case SMB_FIND_FILE_BOTH_DIRECTORY_INFO:
  		cifs_fill_dirent_both(de, info);
  		break;
  	case SMB_FIND_FILE_INFO_STANDARD:
  		cifs_fill_dirent_std(de, info);
  		break;
  	default:

  		cifs_dbg(FYI, "Unknown findfirst level %d
  ", level);

  		return -EINVAL;
  	}
  
  	return 0;
  }

  #define UNICODE_DOT cpu_to_le16(0x2e)
  
  /* return 0 if no match and 1 for . (current directory) and 2 for .. (parent) */

  static int cifs_entry_is_dot(struct cifs_dirent *de, bool is_unicode)

  {
  	int rc = 0;

  	if (!de->name)
  		return 0;

  	if (is_unicode) {
  		__le16 *ufilename = (__le16 *)de->name;
  		if (de->namelen == 2) {
  			/* check for . */
  			if (ufilename[0] == UNICODE_DOT)
  				rc = 1;
  		} else if (de->namelen == 4) {
  			/* check for .. */
  			if (ufilename[0] == UNICODE_DOT &&
  			    ufilename[1] == UNICODE_DOT)
  				rc = 2;
  		}
  	} else /* ASCII */ {
  		if (de->namelen == 1) {
  			if (de->name[0] == '.')
  				rc = 1;
  		} else if (de->namelen == 2) {
  			if (de->name[0] == '.' && de->name[1] == '.')
  				rc = 2;

  		}
  	}
  
  	return rc;
  }

  /* Check if directory that we are searching has changed so we can decide
     whether we can use the cached search results from the previous search */

  static int is_dir_changed(struct file *file)

  {

  	struct inode *inode = file_inode(file);

  	struct cifsInodeInfo *cifsInfo = CIFS_I(inode);

  	if (cifsInfo->time == 0)

  		return 1; /* directory was changed, perhaps due to unlink */
  	else
  		return 0;
  
  }

  static int cifs_save_resume_key(const char *current_entry,

  	struct cifsFileInfo *file_info)

  {

  	struct cifs_dirent de;
  	int rc;

  	rc = cifs_fill_dirent(&de, current_entry, file_info->srch_inf.info_level,
  			      file_info->srch_inf.unicode);
  	if (!rc) {
  		file_info->srch_inf.presume_name = de.name;
  		file_info->srch_inf.resume_name_len = de.namelen;
  		file_info->srch_inf.resume_key = de.resume_key;

  	}

  	return rc;
  }

  /*
   * Find the corresponding entry in the search. Note that the SMB server returns
   * search entries for . and .. which complicates logic here if we choose to
   * parse for them and we do not assume that they are located in the findfirst
   * return buffer. We start counting in the buffer with entry 2 and increment for
   * every entry (do not increment for . or .. entry).
   */
  static int

  find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos,

  		struct file *file, char *full_path,
  		char **current_entry, int *num_to_ret)

  {

  	__u16 search_flags;

  	int rc = 0;
  	int pos_in_buf = 0;
  	loff_t first_entry_in_buffer;

  	loff_t index_to_find = pos;

  	struct cifsFileInfo *cfile = file->private_data;

  	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);

  	struct TCP_Server_Info *server = tcon->ses->server;

  	/* check if index in the buffer */

  	if (!server->ops->query_dir_first || !server->ops->query_dir_next)
  		return -ENOSYS;
  
  	if ((cfile == NULL) || (current_entry == NULL) || (num_to_ret == NULL))

  		return -ENOENT;

  	*current_entry = NULL;
  	first_entry_in_buffer = cfile->srch_inf.index_of_last_entry -
  					cfile->srch_inf.entries_in_buffer;

  	/*
  	 * If first entry in buf is zero then is first buffer
  	 * in search response data which means it is likely . and ..
  	 * will be in this buffer, although some servers do not return
  	 * . and .. for the root of a drive and for those we need
  	 * to start two entries earlier.
  	 */

  	dump_cifs_file_struct(file, "In fce ");

  	if (((index_to_find < cfile->srch_inf.index_of_last_entry) &&
  	     is_dir_changed(file)) || (index_to_find < first_entry_in_buffer)) {

  		/* close and restart search */

  		cifs_dbg(FYI, "search backing up - close and restart search
  ");

  		spin_lock(&cfile->file_info_lock);

  		if (server->ops->dir_needs_close(cfile)) {

  			cfile->invalidHandle = true;

  			spin_unlock(&cfile->file_info_lock);

  			if (server->ops->close_dir)
  				server->ops->close_dir(xid, tcon, &cfile->fid);

  		} else

  			spin_unlock(&cfile->file_info_lock);

  		if (cfile->srch_inf.ntwrk_buf_start) {

  			cifs_dbg(FYI, "freeing SMB ff cache buf on search rewind
  ");

  			if (cfile->srch_inf.smallBuf)
  				cifs_small_buf_release(cfile->srch_inf.

  						ntwrk_buf_start);
  			else

  				cifs_buf_release(cfile->srch_inf.

  						ntwrk_buf_start);

  			cfile->srch_inf.ntwrk_buf_start = NULL;

  		}

  		rc = initiate_cifs_search(xid, file, full_path);

  		if (rc) {

  			cifs_dbg(FYI, "error %d reinitiating a search on rewind
  ",

  				 rc);

  			return rc;
  		}

  		/* FindFirst/Next set last_entry to NULL on malformed reply */

  		if (cfile->srch_inf.last_entry)
  			cifs_save_resume_key(cfile->srch_inf.last_entry, cfile);

  	}

  	search_flags = CIFS_SEARCH_CLOSE_AT_END | CIFS_SEARCH_RETURN_RESUME;
  	if (backup_cred(cifs_sb))
  		search_flags |= CIFS_SEARCH_BACKUP_SEARCH;

  	while ((index_to_find >= cfile->srch_inf.index_of_last_entry) &&
  	       (rc == 0) && !cfile->srch_inf.endOfSearch) {

  		cifs_dbg(FYI, "calling findnext2
  ");

  		rc = server->ops->query_dir_next(xid, tcon, &cfile->fid,
  						 search_flags,
  						 &cfile->srch_inf);

  		/* FindFirst/Next set last_entry to NULL on malformed reply */

  		if (cfile->srch_inf.last_entry)
  			cifs_save_resume_key(cfile->srch_inf.last_entry, cfile);

  		if (rc)

  			return -ENOENT;
  	}

  	if (index_to_find < cfile->srch_inf.index_of_last_entry) {

  		/* we found the buffer that contains the entry */
  		/* scan and find it */
  		int i;

  		char *cur_ent;

  		char *end_of_smb;
  
  		if (cfile->srch_inf.ntwrk_buf_start == NULL) {
  			cifs_dbg(VFS, "ntwrk_buf_start is NULL during readdir
  ");
  			return -EIO;
  		}
  
  		end_of_smb = cfile->srch_inf.ntwrk_buf_start +

  			server->ops->calc_smb_size(

  					cfile->srch_inf.ntwrk_buf_start,
  					server);

  
  		cur_ent = cfile->srch_inf.srch_entries_start;
  		first_entry_in_buffer = cfile->srch_inf.index_of_last_entry
  					- cfile->srch_inf.entries_in_buffer;

  		pos_in_buf = index_to_find - first_entry_in_buffer;

  		cifs_dbg(FYI, "found entry - pos_in_buf %d
  ", pos_in_buf);

  		for (i = 0; (i < (pos_in_buf)) && (cur_ent != NULL); i++) {

  			/* go entry by entry figuring out which is first */

  			cur_ent = nxt_dir_entry(cur_ent, end_of_smb,
  						cfile->srch_inf.info_level);

  		}

  		if ((cur_ent == NULL) && (i < pos_in_buf)) {

  			/* BB fixme - check if we should flag this error */

  			cifs_dbg(VFS, "reached end of buf searching for pos in buf %d index to find %lld rc %d
  ",
  				 pos_in_buf, index_to_find, rc);

  		}
  		rc = 0;

  		*current_entry = cur_ent;

  	} else {

  		cifs_dbg(FYI, "index not in buffer - could not findnext into it
  ");

  		return 0;
  	}

  	if (pos_in_buf >= cfile->srch_inf.entries_in_buffer) {

  		cifs_dbg(FYI, "can not return entries pos_in_buf beyond last
  ");

  		*num_to_ret = 0;
  	} else

  		*num_to_ret = cfile->srch_inf.entries_in_buffer - pos_in_buf;

  
  	return rc;
  }

  static int cifs_filldir(char *find_entry, struct file *file,
  		struct dir_context *ctx,
  		char *scratch_buf, unsigned int max_len)

  {

  	struct cifsFileInfo *file_info = file->private_data;

  	struct super_block *sb = file_inode(file)->i_sb;

  	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);

  	struct cifs_dirent de = { NULL, };

  	struct cifs_fattr fattr;

  	struct qstr name;

  	int rc = 0;

  	ino_t ino;

  	rc = cifs_fill_dirent(&de, find_entry, file_info->srch_inf.info_level,
  			      file_info->srch_inf.unicode);
  	if (rc)
  		return rc;

  	if (de.namelen > max_len) {

  		cifs_dbg(VFS, "bad search response length %zd past smb end
  ",
  			 de.namelen);

  		return -EINVAL;
  	}

  	/* skip . and .. since we added them first */

  	if (cifs_entry_is_dot(&de, file_info->srch_inf.unicode))

  		return 0;

  	if (file_info->srch_inf.unicode) {
  		struct nls_table *nlt = cifs_sb->local_nls;

  		int map_type;

  		map_type = cifs_remap(cifs_sb);

  		name.name = scratch_buf;
  		name.len =

  			cifs_from_utf16((char *)name.name, (__le16 *)de.name,
  					UNICODE_NAME_MAX,
  					min_t(size_t, de.namelen,

  					      (size_t)max_len), nlt, map_type);

  		name.len -= nls_nullsize(nlt);
  	} else {
  		name.name = de.name;
  		name.len = de.namelen;
  	}

  	switch (file_info->srch_inf.info_level) {

  	case SMB_FIND_FILE_POSIX_INFO:
  		cifs_posix_to_fattr(&fattr,
  				    (struct smb2_posix_info *)find_entry,
  				    cifs_sb);
  		break;

  	case SMB_FIND_FILE_UNIX:

  		cifs_unix_basic_to_fattr(&fattr,

  					 &((FILE_UNIX_INFO *)find_entry)->basic,
  					 cifs_sb);
  		break;
  	case SMB_FIND_FILE_INFO_STANDARD:
  		cifs_std_info_to_fattr(&fattr,
  				       (FIND_FILE_STANDARD_INFO *)find_entry,
  				       cifs_sb);
  		break;

  	case SMB_FIND_FILE_ID_FULL_DIR_INFO:
  		cifs_fulldir_info_to_fattr(&fattr,
  					   (SEARCH_ID_FULL_DIR_INFO *)find_entry,
  					   cifs_sb);
  		break;

  	default:
  		cifs_dir_info_to_fattr(&fattr,
  				       (FILE_DIRECTORY_INFO *)find_entry,
  				       cifs_sb);
  		break;
  	}

  	if (de.ino && (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
  		fattr.cf_uniqueid = de.ino;

  	} else {

  		fattr.cf_uniqueid = iunique(sb, ROOT_I);

  		cifs_autodisable_serverino(cifs_sb);
  	}

  	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) &&

  	    couldbe_mf_symlink(&fattr))

  		/*
  		 * trying to get the type and mode can be slow,
  		 * so just call those regular files for now, and mark
  		 * for reval
  		 */
  		fattr.cf_flags |= CIFS_FATTR_NEED_REVAL;

  	cifs_prime_dcache(file_dentry(file), &name, &fattr);

  	ino = cifs_uniqueid_to_ino_t(fattr.cf_uniqueid);

  	return !dir_emit(ctx, name.name, name.len, ino, fattr.cf_dtype);

  }

  int cifs_readdir(struct file *file, struct dir_context *ctx)

  {
  	int rc = 0;

  	unsigned int xid;
  	int i;

  	struct cifs_tcon *tcon;

  	struct cifsFileInfo *cifsFile = NULL;

  	char *current_entry;

  	int num_to_fill = 0;

  	char *tmp_buf = NULL;

  	char *end_of_smb;

  	unsigned int max_len;

  	char *full_path = NULL;

  	xid = get_xid();

  	full_path = build_path_from_dentry(file_dentry(file));
  	if (full_path == NULL) {
  		rc = -ENOMEM;
  		goto rddir2_exit;
  	}

  	/*
  	 * Ensure FindFirst doesn't fail before doing filldir() for '.' and
  	 * '..'. Otherwise we won't be able to notify VFS in case of failure.
  	 */
  	if (file->private_data == NULL) {

  		rc = initiate_cifs_search(xid, file, full_path);

  		cifs_dbg(FYI, "initiate cifs search rc %d
  ", rc);

  		if (rc)
  			goto rddir2_exit;
  	}

  	if (!dir_emit_dots(file, ctx))
  		goto rddir2_exit;

  	/* 1) If search is active,
  		is in current search buffer?
  		if it before then restart search
  		if after then keep searching till find it */

  	cifsFile = file->private_data;
  	if (cifsFile->srch_inf.endOfSearch) {
  		if (cifsFile->srch_inf.emptyDir) {
  			cifs_dbg(FYI, "End of search, empty dir
  ");
  			rc = 0;

  			goto rddir2_exit;
  		}

  	} /* else {
  		cifsFile->invalidHandle = true;
  		tcon->ses->server->close(xid, tcon, &cifsFile->fid);
  	} */
  
  	tcon = tlink_tcon(cifsFile->tlink);

  	rc = find_cifs_entry(xid, tcon, ctx->pos, file, full_path,
  			     &current_entry, &num_to_fill);

  	if (rc) {
  		cifs_dbg(FYI, "fce error %d
  ", rc);
  		goto rddir2_exit;
  	} else if (current_entry != NULL) {
  		cifs_dbg(FYI, "entry %lld found
  ", ctx->pos);
  	} else {

  		cifs_dbg(FYI, "Could not find entry
  ");

  		goto rddir2_exit;
  	}
  	cifs_dbg(FYI, "loop through %d times filling dir for net buf %p
  ",
  		 num_to_fill, cifsFile->srch_inf.ntwrk_buf_start);
  	max_len = tcon->ses->server->ops->calc_smb_size(

  			cifsFile->srch_inf.ntwrk_buf_start,
  			tcon->ses->server);

  	end_of_smb = cifsFile->srch_inf.ntwrk_buf_start + max_len;
  
  	tmp_buf = kmalloc(UNICODE_NAME_MAX, GFP_KERNEL);
  	if (tmp_buf == NULL) {
  		rc = -ENOMEM;
  		goto rddir2_exit;
  	}
  
  	for (i = 0; i < num_to_fill; i++) {
  		if (current_entry == NULL) {
  			/* evaluate whether this case is an error */
  			cifs_dbg(VFS, "past SMB end,  num to fill %d i %d
  ",
  				 num_to_fill, i);

  			break;
  		}

  		/*
  		 * if buggy server returns . and .. late do we want to
  		 * check for that here?
  		 */

  		*tmp_buf = 0;

  		rc = cifs_filldir(current_entry, file, ctx,
  				  tmp_buf, max_len);
  		if (rc) {
  			if (rc > 0)

  				rc = 0;

  			break;

  		}

  
  		ctx->pos++;
  		if (ctx->pos ==
  			cifsFile->srch_inf.index_of_last_entry) {
  			cifs_dbg(FYI, "last entry in buf at pos %lld %s
  ",
  				 ctx->pos, tmp_buf);
  			cifs_save_resume_key(current_entry, cifsFile);
  			break;
  		} else
  			current_entry =
  				nxt_dir_entry(current_entry, end_of_smb,
  					cifsFile->srch_inf.info_level);
  	}
  	kfree(tmp_buf);

  
  rddir2_exit:

  	kfree(full_path);

  	free_xid(xid);

  	return rc;
  }