fs/cifs/cifs_unicode.c - kernel/quantenna - Git at Google

 /*
  *   fs/cifs/cifs_unicode.c
  *
  *   Copyright (c) International Business Machines  Corp., 2000,2009
  *   Modified by Steve French (sfrench@us.ibm.com)
  *
  *   This program is free software;  you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation; either version 2 of the License, or
  *   (at your option) any later version.
  *
  *   This program 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 General Public License for more details.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program;  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/slab.h>
 #include "cifs_fs_sb.h"
 #include "cifs_unicode.h"
 #include "cifs_uniupr.h"
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifs_debug.h"

 int cifs_remap(struct cifs_sb_info *cifs_sb)
 {
 	int map_type;

 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
 		map_type = SFM_MAP_UNI_RSVD;
 	else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
 		map_type = SFU_MAP_UNI_RSVD;
 	else
 		map_type = NO_MAP_UNI_RSVD;

 	return map_type;
 }

 /* Convert character using the SFU - "Services for Unix" remapping range */
 static bool
 convert_sfu_char(const __u16 src_char, char *target)
 {
 	/*
 	 * BB: Cannot handle remapping UNI_SLASH until all the calls to
 	 *     build_path_from_dentry are modified, as they use slash as
 	 *     separator.
 	 */
 	switch (src_char) {
 	case UNI_COLON:
 		*target = ':';
 		break;
 	case UNI_ASTERISK:
 		*target = '*';
 		break;
 	case UNI_QUESTION:
 		*target = '?';
 		break;
 	case UNI_PIPE:
 		*target = '|';
 		break;
 	case UNI_GRTRTHAN:
 		*target = '>';
 		break;
 	case UNI_LESSTHAN:
 		*target = '<';
 		break;
 	default:
 		return false;
 	}
 	return true;
 }

 /* Convert character using the SFM - "Services for Mac" remapping range */
 static bool
 convert_sfm_char(const __u16 src_char, char *target)
 {
 	switch (src_char) {
 	case SFM_COLON:
 		*target = ':';
 		break;
 	case SFM_ASTERISK:
 		*target = '*';
 		break;
 	case SFM_QUESTION:
 		*target = '?';
 		break;
 	case SFM_PIPE:
 		*target = '|';
 		break;
 	case SFM_GRTRTHAN:
 		*target = '>';
 		break;
 	case SFM_LESSTHAN:
 		*target = '<';
 		break;
 	case SFM_SLASH:
 		*target = '\\';
 		break;
 	case SFM_SPACE:
 		*target = ' ';
 		break;
 	case SFM_PERIOD:
 		*target = '.';
 		break;
 	default:
 		return false;
 	}
 	return true;
 }


 /*
  * cifs_mapchar - convert a host-endian char to proper char in codepage
  * @target - where converted character should be copied
  * @src_char - 2 byte host-endian source character
  * @cp - codepage to which character should be converted
  * @map_type - How should the 7 NTFS/SMB reserved characters be mapped to UCS2?
  *
  * This function handles the conversion of a single character. It is the
  * responsibility of the caller to ensure that the target buffer is large
  * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
  */
 static int
 cifs_mapchar(char *target, const __u16 *from, const struct nls_table *cp,
 	     int maptype)
 {
 	int len = 1;
 	__u16 src_char;

 	src_char = *from;

 	if ((maptype == SFM_MAP_UNI_RSVD) && convert_sfm_char(src_char, target))
 		return len;
 	else if ((maptype == SFU_MAP_UNI_RSVD) &&
 		  convert_sfu_char(src_char, target))
 		return len;

 	/* if character not one of seven in special remap set */
 	len = cp->uni2char(src_char, target, NLS_MAX_CHARSET_SIZE);
 	if (len <= 0)
 		goto surrogate_pair;

 	return len;

 surrogate_pair:
 	/* convert SURROGATE_PAIR and IVS */
 	if (strcmp(cp->charset, "utf8"))
 		goto unknown;
 	len = utf16s_to_utf8s(from, 3, UTF16_LITTLE_ENDIAN, target, 6);
 	if (len <= 0)
 		goto unknown;
 	return len;

 unknown:
 	*target = '?';
 	len = 1;
 	return len;
 }

 /*
  * cifs_from_utf16 - convert utf16le string to local charset
  * @to - destination buffer
  * @from - source buffer
  * @tolen - destination buffer size (in bytes)
  * @fromlen - source buffer size (in bytes)
  * @codepage - codepage to which characters should be converted
  * @mapchar - should characters be remapped according to the mapchars option?
  *
  * Convert a little-endian utf16le string (as sent by the server) to a string
  * in the provided codepage. The tolen and fromlen parameters are to ensure
  * that the code doesn't walk off of the end of the buffer (which is always
  * a danger if the alignment of the source buffer is off). The destination
  * string is always properly null terminated and fits in the destination
  * buffer. Returns the length of the destination string in bytes (including
  * null terminator).
  *
  * Note that some windows versions actually send multiword UTF-16 characters
  * instead of straight UTF16-2. The linux nls routines however aren't able to
  * deal with those characters properly. In the event that we get some of
  * those characters, they won't be translated properly.
  */
 int
 cifs_from_utf16(char *to, const __le16 *from, int tolen, int fromlen,
 		const struct nls_table *codepage, int map_type)
 {
 	int i, charlen, safelen;
 	int outlen = 0;
 	int nullsize = nls_nullsize(codepage);
 	int fromwords = fromlen / 2;
 	char tmp[NLS_MAX_CHARSET_SIZE];
 	__u16 ftmp[3];		/* ftmp[3] = 3array x 2bytes = 6bytes UTF-16 */

 	/*
 	 * because the chars can be of varying widths, we need to take care
 	 * not to overflow the destination buffer when we get close to the
 	 * end of it. Until we get to this offset, we don't need to check
 	 * for overflow however.
 	 */
 	safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);

 	for (i = 0; i < fromwords; i++) {
 		ftmp[0] = get_unaligned_le16(&from[i]);
 		if (ftmp[0] == 0)
 			break;
 		if (i + 1 < fromwords)
 			ftmp[1] = get_unaligned_le16(&from[i + 1]);
 		else
 			ftmp[1] = 0;
 		if (i + 2 < fromwords)
 			ftmp[2] = get_unaligned_le16(&from[i + 2]);
 		else
 			ftmp[2] = 0;

 		/*
 		 * check to see if converting this character might make the
 		 * conversion bleed into the null terminator
 		 */
 		if (outlen >= safelen) {
 			charlen = cifs_mapchar(tmp, ftmp, codepage, map_type);
 			if ((outlen + charlen) > (tolen - nullsize))
 				break;
 		}

 		/* put converted char into 'to' buffer */
 		charlen = cifs_mapchar(&to[outlen], ftmp, codepage, map_type);
 		outlen += charlen;

 		/* charlen (=bytes of UTF-8 for 1 character)
 		 * 4bytes UTF-8(surrogate pair) is charlen=4
 		 *   (4bytes UTF-16 code)
 		 * 7-8bytes UTF-8(IVS) is charlen=3+4 or 4+4
 		 *   (2 UTF-8 pairs divided to 2 UTF-16 pairs) */
 		if (charlen == 4)
 			i++;
 		else if (charlen >= 5)
 			/* 5-6bytes UTF-8 */
 			i += 2;
 	}

 	/* properly null-terminate string */
 	for (i = 0; i < nullsize; i++)
 		to[outlen++] = 0;

 	return outlen;
 }

 /*
  * NAME:	cifs_strtoUTF16()
  *
  * FUNCTION:	Convert character string to unicode string
  *
  */
 int
 cifs_strtoUTF16(__le16 *to, const char *from, int len,
 	      const struct nls_table *codepage)
 {
 	int charlen;
 	int i;
 	wchar_t wchar_to; /* needed to quiet sparse */

 	/* special case for utf8 to handle no plane0 chars */
 	if (!strcmp(codepage->charset, "utf8")) {
 		/*
 		 * convert utf8 -> utf16, we assume we have enough space
 		 * as caller should have assumed conversion does not overflow
 		 * in destination len is length in wchar_t units (16bits)
 		 */
 		i  = utf8s_to_utf16s(from, len, UTF16_LITTLE_ENDIAN,
 				       (wchar_t *) to, len);

 		/* if success terminate and exit */
 		if (i >= 0)
 			goto success;
 		/*
 		 * if fails fall back to UCS encoding as this
 		 * function should not return negative values
 		 * currently can fail only if source contains
 		 * invalid encoded characters
 		 */
 	}

 	for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
 		charlen = codepage->char2uni(from, len, &wchar_to);
 		if (charlen < 1) {
 			cifs_dbg(VFS, "strtoUTF16: char2uni of 0x%x returned %d\n",
 				 *from, charlen);
 			/* A question mark */
 			wchar_to = 0x003f;
 			charlen = 1;
 		}
 		put_unaligned_le16(wchar_to, &to[i]);
 	}

 success:
 	put_unaligned_le16(0, &to[i]);
 	return i;
 }

 /*
  * cifs_utf16_bytes - how long will a string be after conversion?
  * @utf16 - pointer to input string
  * @maxbytes - don't go past this many bytes of input string
  * @codepage - destination codepage
  *
  * Walk a utf16le string and return the number of bytes that the string will
  * be after being converted to the given charset, not including any null
  * termination required. Don't walk past maxbytes in the source buffer.
  */
 int
 cifs_utf16_bytes(const __le16 *from, int maxbytes,
 		const struct nls_table *codepage)
 {
 	int i;
 	int charlen, outlen = 0;
 	int maxwords = maxbytes / 2;
 	char tmp[NLS_MAX_CHARSET_SIZE];
 	__u16 ftmp[3];

 	for (i = 0; i < maxwords; i++) {
 		ftmp[0] = get_unaligned_le16(&from[i]);
 		if (ftmp[0] == 0)
 			break;
 		if (i + 1 < maxwords)
 			ftmp[1] = get_unaligned_le16(&from[i + 1]);
 		else
 			ftmp[1] = 0;
 		if (i + 2 < maxwords)
 			ftmp[2] = get_unaligned_le16(&from[i + 2]);
 		else
 			ftmp[2] = 0;

 		charlen = cifs_mapchar(tmp, ftmp, codepage, NO_MAP_UNI_RSVD);
 		outlen += charlen;
 	}

 	return outlen;
 }

 /*
  * cifs_strndup_from_utf16 - copy a string from wire format to the local
  * codepage
  * @src - source string
  * @maxlen - don't walk past this many bytes in the source string
  * @is_unicode - is this a unicode string?
  * @codepage - destination codepage
  *
  * Take a string given by the server, convert it to the local codepage and
  * put it in a new buffer. Returns a pointer to the new string or NULL on
  * error.
  */
 char *
 cifs_strndup_from_utf16(const char *src, const int maxlen,
 			const bool is_unicode, const struct nls_table *codepage)
 {
 	int len;
 	char *dst;

 	if (is_unicode) {
 		len = cifs_utf16_bytes((__le16 *) src, maxlen, codepage);
 		len += nls_nullsize(codepage);
 		dst = kmalloc(len, GFP_KERNEL);
 		if (!dst)
 			return NULL;
 		cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage,
 			       NO_MAP_UNI_RSVD);
 	} else {
 		len = strnlen(src, maxlen);
 		len++;
 		dst = kmalloc(len, GFP_KERNEL);
 		if (!dst)
 			return NULL;
 		strlcpy(dst, src, len);
 	}

 	return dst;
 }

 static __le16 convert_to_sfu_char(char src_char)
 {
 	__le16 dest_char;

 	switch (src_char) {
 	case ':':
 		dest_char = cpu_to_le16(UNI_COLON);
 		break;
 	case '*':
 		dest_char = cpu_to_le16(UNI_ASTERISK);
 		break;
 	case '?':
 		dest_char = cpu_to_le16(UNI_QUESTION);
 		break;
 	case '<':
 		dest_char = cpu_to_le16(UNI_LESSTHAN);
 		break;
 	case '>':
 		dest_char = cpu_to_le16(UNI_GRTRTHAN);
 		break;
 	case '|':
 		dest_char = cpu_to_le16(UNI_PIPE);
 		break;
 	default:
 		dest_char = 0;
 	}

 	return dest_char;
 }

 static __le16 convert_to_sfm_char(char src_char, bool end_of_string)
 {
 	__le16 dest_char;

 	switch (src_char) {
 	case ':':
 		dest_char = cpu_to_le16(SFM_COLON);
 		break;
 	case '*':
 		dest_char = cpu_to_le16(SFM_ASTERISK);
 		break;
 	case '?':
 		dest_char = cpu_to_le16(SFM_QUESTION);
 		break;
 	case '<':
 		dest_char = cpu_to_le16(SFM_LESSTHAN);
 		break;
 	case '>':
 		dest_char = cpu_to_le16(SFM_GRTRTHAN);
 		break;
 	case '|':
 		dest_char = cpu_to_le16(SFM_PIPE);
 		break;
 	case '.':
 		if (end_of_string)
 			dest_char = cpu_to_le16(SFM_PERIOD);
 		else
 			dest_char = 0;
 		break;
 	case ' ':
 		if (end_of_string)
 			dest_char = cpu_to_le16(SFM_SPACE);
 		else
 			dest_char = 0;
 		break;
 	default:
 		dest_char = 0;
 	}

 	return dest_char;
 }

 /*
  * Convert 16 bit Unicode pathname to wire format from string in current code
  * page. Conversion may involve remapping up the six characters that are
  * only legal in POSIX-like OS (if they are present in the string). Path
  * names are little endian 16 bit Unicode on the wire
  */
 int
 cifsConvertToUTF16(__le16 *target, const char *source, int srclen,
 		 const struct nls_table *cp, int map_chars)
 {
 	int i, charlen;
 	int j = 0;
 	char src_char;
 	__le16 dst_char;
 	wchar_t tmp;
 	wchar_t *wchar_to;	/* UTF-16 */
 	int ret;
 	unicode_t u;

 	if (map_chars == NO_MAP_UNI_RSVD)
 		return cifs_strtoUTF16(target, source, PATH_MAX, cp);

 	wchar_to = kzalloc(6, GFP_KERNEL);

 	for (i = 0; i < srclen; j++) {
 		src_char = source[i];
 		charlen = 1;

 		/* check if end of string */
 		if (src_char == 0)
 			goto ctoUTF16_out;

 		/* see if we must remap this char */
 		if (map_chars == SFU_MAP_UNI_RSVD)
 			dst_char = convert_to_sfu_char(src_char);
 		else if (map_chars == SFM_MAP_UNI_RSVD) {
 			bool end_of_string;

 			if (i == srclen - 1)
 				end_of_string = true;
 			else
 				end_of_string = false;

 			dst_char = convert_to_sfm_char(src_char, end_of_string);
 		} else
 			dst_char = 0;
 		/*
 		 * FIXME: We can not handle remapping backslash (UNI_SLASH)
 		 * until all the calls to build_path_from_dentry are modified,
 		 * as they use backslash as separator.
 		 */
 		if (dst_char == 0) {
 			charlen = cp->char2uni(source + i, srclen - i, &tmp);
 			dst_char = cpu_to_le16(tmp);

 			/*
 			 * if no match, use question mark, which at least in
 			 * some cases serves as wild card
 			 */
 			if (charlen > 0)
 				goto ctoUTF16;

 			/* convert SURROGATE_PAIR */
 			if (strcmp(cp->charset, "utf8") || !wchar_to)
 				goto unknown;
 			if (*(source + i) & 0x80) {
 				charlen = utf8_to_utf32(source + i, 6, &u);
 				if (charlen < 0)
 					goto unknown;
 			} else
 				goto unknown;
 			ret  = utf8s_to_utf16s(source + i, charlen,
 					       UTF16_LITTLE_ENDIAN,
 					       wchar_to, 6);
 			if (ret < 0)
 				goto unknown;

 			i += charlen;
 			dst_char = cpu_to_le16(*wchar_to);
 			if (charlen <= 3)
 				/* 1-3bytes UTF-8 to 2bytes UTF-16 */
 				put_unaligned(dst_char, &target[j]);
 			else if (charlen == 4) {
 				/* 4bytes UTF-8(surrogate pair) to 4bytes UTF-16
 				 * 7-8bytes UTF-8(IVS) divided to 2 UTF-16
 				 *   (charlen=3+4 or 4+4) */
 				put_unaligned(dst_char, &target[j]);
 				dst_char = cpu_to_le16(*(wchar_to + 1));
 				j++;
 				put_unaligned(dst_char, &target[j]);
 			} else if (charlen >= 5) {
 				/* 5-6bytes UTF-8 to 6bytes UTF-16 */
 				put_unaligned(dst_char, &target[j]);
 				dst_char = cpu_to_le16(*(wchar_to + 1));
 				j++;
 				put_unaligned(dst_char, &target[j]);
 				dst_char = cpu_to_le16(*(wchar_to + 2));
 				j++;
 				put_unaligned(dst_char, &target[j]);
 			}
 			continue;

 unknown:
 			dst_char = cpu_to_le16(0x003f);
 			charlen = 1;
 		}

 ctoUTF16:
 		/*
 		 * character may take more than one byte in the source string,
 		 * but will take exactly two bytes in the target string
 		 */
 		i += charlen;
 		put_unaligned(dst_char, &target[j]);
 	}

 ctoUTF16_out:
 	put_unaligned(0, &target[j]); /* Null terminate target unicode string */
 	kfree(wchar_to);
 	return j;
 }

 #ifdef CONFIG_CIFS_SMB2
 /*
  * cifs_local_to_utf16_bytes - how long will a string be after conversion?
  * @from - pointer to input string
  * @maxbytes - don't go past this many bytes of input string
  * @codepage - source codepage
  *
  * Walk a string and return the number of bytes that the string will
  * be after being converted to the given charset, not including any null
  * termination required. Don't walk past maxbytes in the source buffer.
  */

 static int
 cifs_local_to_utf16_bytes(const char *from, int len,
 			  const struct nls_table *codepage)
 {
 	int charlen;
 	int i;
 	wchar_t wchar_to;

 	for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
 		charlen = codepage->char2uni(from, len, &wchar_to);
 		/* Failed conversion defaults to a question mark */
 		if (charlen < 1)
 			charlen = 1;
 	}
 	return 2 * i; /* UTF16 characters are two bytes */
 }

 /*
  * cifs_strndup_to_utf16 - copy a string to wire format from the local codepage
  * @src - source string
  * @maxlen - don't walk past this many bytes in the source string
  * @utf16_len - the length of the allocated string in bytes (including null)
  * @cp - source codepage
  * @remap - map special chars
  *
  * Take a string convert it from the local codepage to UTF16 and
  * put it in a new buffer. Returns a pointer to the new string or NULL on
  * error.
  */
 __le16 *
 cifs_strndup_to_utf16(const char *src, const int maxlen, int *utf16_len,
 		      const struct nls_table *cp, int remap)
 {
 	int len;
 	__le16 *dst;

 	len = cifs_local_to_utf16_bytes(src, maxlen, cp);
 	len += 2; /* NULL */
 	dst = kmalloc(len, GFP_KERNEL);
 	if (!dst) {
 		*utf16_len = 0;
 		return NULL;
 	}
 	cifsConvertToUTF16(dst, src, strlen(src), cp, remap);
 	*utf16_len = len;
 	return dst;
 }
 #endif /* CONFIG_CIFS_SMB2 */
	/*
	* fs/cifs/cifs_unicode.c
	*
	* Copyright (c) International Business Machines Corp., 2000,2009
	* Modified by Steve French (sfrench@us.ibm.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program 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 General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; 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/slab.h>
	#include "cifs_fs_sb.h"
	#include "cifs_unicode.h"
	#include "cifs_uniupr.h"
	#include "cifspdu.h"
	#include "cifsglob.h"
	#include "cifs_debug.h"

	int cifs_remap(struct cifs_sb_info *cifs_sb)
	{
	int map_type;

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
	map_type = SFM_MAP_UNI_RSVD;
	else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
	map_type = SFU_MAP_UNI_RSVD;
	else
	map_type = NO_MAP_UNI_RSVD;

	return map_type;
	}

	/* Convert character using the SFU - "Services for Unix" remapping range */
	static bool
	convert_sfu_char(const __u16 src_char, char *target)
	{
	/*
	* BB: Cannot handle remapping UNI_SLASH until all the calls to
	* build_path_from_dentry are modified, as they use slash as
	* separator.
	*/
	switch (src_char) {
	case UNI_COLON:
	*target = ':';
	break;
	case UNI_ASTERISK:
	target = '';
	break;
	case UNI_QUESTION:
	*target = '?';
	break;
	case UNI_PIPE:
	*target = '\|';
	break;
	case UNI_GRTRTHAN:
	*target = '>';
	break;
	case UNI_LESSTHAN:
	*target = '<';
	break;
	default:
	return false;
	}
	return true;
	}

	/* Convert character using the SFM - "Services for Mac" remapping range */
	static bool
	convert_sfm_char(const __u16 src_char, char *target)
	{
	switch (src_char) {
	case SFM_COLON:
	*target = ':';
	break;
	case SFM_ASTERISK:
	target = '';
	break;
	case SFM_QUESTION:
	*target = '?';
	break;
	case SFM_PIPE:
	*target = '\|';
	break;
	case SFM_GRTRTHAN:
	*target = '>';
	break;
	case SFM_LESSTHAN:
	*target = '<';
	break;
	case SFM_SLASH:
	*target = '\\';
	break;
	case SFM_SPACE:
	*target = ' ';
	break;
	case SFM_PERIOD:
	*target = '.';
	break;
	default:
	return false;
	}
	return true;
	}


	/*
	* cifs_mapchar - convert a host-endian char to proper char in codepage
	* @target - where converted character should be copied
	* @src_char - 2 byte host-endian source character
	* @cp - codepage to which character should be converted
	* @map_type - How should the 7 NTFS/SMB reserved characters be mapped to UCS2?
	*
	* This function handles the conversion of a single character. It is the
	* responsibility of the caller to ensure that the target buffer is large
	* enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
	*/
	static int
	cifs_mapchar(char target, const __u16 from, const struct nls_table *cp,
	int maptype)
	{
	int len = 1;
	__u16 src_char;

	src_char = *from;

	if ((maptype == SFM_MAP_UNI_RSVD) && convert_sfm_char(src_char, target))
	return len;
	else if ((maptype == SFU_MAP_UNI_RSVD) &&
	convert_sfu_char(src_char, target))
	return len;

	/* if character not one of seven in special remap set */
	len = cp->uni2char(src_char, target, NLS_MAX_CHARSET_SIZE);
	if (len <= 0)
	goto surrogate_pair;

	return len;

	surrogate_pair:
	/* convert SURROGATE_PAIR and IVS */
	if (strcmp(cp->charset, "utf8"))
	goto unknown;
	len = utf16s_to_utf8s(from, 3, UTF16_LITTLE_ENDIAN, target, 6);
	if (len <= 0)
	goto unknown;
	return len;

	unknown:
	*target = '?';
	len = 1;
	return len;
	}

	/*
	* cifs_from_utf16 - convert utf16le string to local charset
	* @to - destination buffer
	* @from - source buffer
	* @tolen - destination buffer size (in bytes)
	* @fromlen - source buffer size (in bytes)
	* @codepage - codepage to which characters should be converted
	* @mapchar - should characters be remapped according to the mapchars option?
	*
	* Convert a little-endian utf16le string (as sent by the server) to a string
	* in the provided codepage. The tolen and fromlen parameters are to ensure
	* that the code doesn't walk off of the end of the buffer (which is always
	* a danger if the alignment of the source buffer is off). The destination
	* string is always properly null terminated and fits in the destination
	* buffer. Returns the length of the destination string in bytes (including
	* null terminator).
	*
	* Note that some windows versions actually send multiword UTF-16 characters
	* instead of straight UTF16-2. The linux nls routines however aren't able to
	* deal with those characters properly. In the event that we get some of
	* those characters, they won't be translated properly.
	*/
	int
	cifs_from_utf16(char to, const __le16 from, int tolen, int fromlen,
	const struct nls_table *codepage, int map_type)
	{
	int i, charlen, safelen;
	int outlen = 0;
	int nullsize = nls_nullsize(codepage);
	int fromwords = fromlen / 2;
	char tmp[NLS_MAX_CHARSET_SIZE];
	__u16 ftmp[3]; /* ftmp[3] = 3array x 2bytes = 6bytes UTF-16 */

	/*
	* because the chars can be of varying widths, we need to take care
	* not to overflow the destination buffer when we get close to the
	* end of it. Until we get to this offset, we don't need to check
	* for overflow however.
	*/
	safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);

	for (i = 0; i < fromwords; i++) {
	ftmp[0] = get_unaligned_le16(&from[i]);
	if (ftmp[0] == 0)
	break;
	if (i + 1 < fromwords)
	ftmp[1] = get_unaligned_le16(&from[i + 1]);
	else
	ftmp[1] = 0;
	if (i + 2 < fromwords)
	ftmp[2] = get_unaligned_le16(&from[i + 2]);
	else
	ftmp[2] = 0;

	/*
	* check to see if converting this character might make the
	* conversion bleed into the null terminator
	*/
	if (outlen >= safelen) {
	charlen = cifs_mapchar(tmp, ftmp, codepage, map_type);
	if ((outlen + charlen) > (tolen - nullsize))
	break;
	}

	/* put converted char into 'to' buffer */
	charlen = cifs_mapchar(&to[outlen], ftmp, codepage, map_type);
	outlen += charlen;

	/* charlen (=bytes of UTF-8 for 1 character)
	* 4bytes UTF-8(surrogate pair) is charlen=4
	* (4bytes UTF-16 code)
	* 7-8bytes UTF-8(IVS) is charlen=3+4 or 4+4
	* (2 UTF-8 pairs divided to 2 UTF-16 pairs) */
	if (charlen == 4)
	i++;
	else if (charlen >= 5)
	/* 5-6bytes UTF-8 */
	i += 2;
	}

	/* properly null-terminate string */
	for (i = 0; i < nullsize; i++)
	to[outlen++] = 0;

	return outlen;
	}

	/*
	* NAME: cifs_strtoUTF16()
	*
	* FUNCTION: Convert character string to unicode string
	*
	*/
	int
	cifs_strtoUTF16(__le16 to, const char from, int len,
	const struct nls_table *codepage)
	{
	int charlen;
	int i;
	wchar_t wchar_to; /* needed to quiet sparse */

	/* special case for utf8 to handle no plane0 chars */
	if (!strcmp(codepage->charset, "utf8")) {
	/*
	* convert utf8 -> utf16, we assume we have enough space
	* as caller should have assumed conversion does not overflow
	* in destination len is length in wchar_t units (16bits)
	*/
	i = utf8s_to_utf16s(from, len, UTF16_LITTLE_ENDIAN,
	(wchar_t *) to, len);

	/* if success terminate and exit */
	if (i >= 0)
	goto success;
	/*
	* if fails fall back to UCS encoding as this
	* function should not return negative values
	* currently can fail only if source contains
	* invalid encoded characters
	*/
	}

	for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
	charlen = codepage->char2uni(from, len, &wchar_to);
	if (charlen < 1) {
	cifs_dbg(VFS, "strtoUTF16: char2uni of 0x%x returned %d\n",
	*from, charlen);
	/* A question mark */
	wchar_to = 0x003f;
	charlen = 1;
	}
	put_unaligned_le16(wchar_to, &to[i]);
	}

	success:
	put_unaligned_le16(0, &to[i]);
	return i;
	}

	/*
	* cifs_utf16_bytes - how long will a string be after conversion?
	* @utf16 - pointer to input string
	* @maxbytes - don't go past this many bytes of input string
	* @codepage - destination codepage
	*
	* Walk a utf16le string and return the number of bytes that the string will
	* be after being converted to the given charset, not including any null
	* termination required. Don't walk past maxbytes in the source buffer.
	*/
	int
	cifs_utf16_bytes(const __le16 *from, int maxbytes,
	const struct nls_table *codepage)
	{
	int i;
	int charlen, outlen = 0;
	int maxwords = maxbytes / 2;
	char tmp[NLS_MAX_CHARSET_SIZE];
	__u16 ftmp[3];

	for (i = 0; i < maxwords; i++) {
	ftmp[0] = get_unaligned_le16(&from[i]);
	if (ftmp[0] == 0)
	break;
	if (i + 1 < maxwords)
	ftmp[1] = get_unaligned_le16(&from[i + 1]);
	else
	ftmp[1] = 0;
	if (i + 2 < maxwords)
	ftmp[2] = get_unaligned_le16(&from[i + 2]);
	else
	ftmp[2] = 0;

	charlen = cifs_mapchar(tmp, ftmp, codepage, NO_MAP_UNI_RSVD);
	outlen += charlen;
	}

	return outlen;
	}

	/*
	* cifs_strndup_from_utf16 - copy a string from wire format to the local
	* codepage
	* @src - source string
	* @maxlen - don't walk past this many bytes in the source string
	* @is_unicode - is this a unicode string?
	* @codepage - destination codepage
	*
	* Take a string given by the server, convert it to the local codepage and
	* put it in a new buffer. Returns a pointer to the new string or NULL on
	* error.
	*/
	char *
	cifs_strndup_from_utf16(const char *src, const int maxlen,
	const bool is_unicode, const struct nls_table *codepage)
	{
	int len;
	char *dst;

	if (is_unicode) {
	len = cifs_utf16_bytes((__le16 *) src, maxlen, codepage);
	len += nls_nullsize(codepage);
	dst = kmalloc(len, GFP_KERNEL);
	if (!dst)
	return NULL;
	cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage,
	NO_MAP_UNI_RSVD);
	} else {
	len = strnlen(src, maxlen);
	len++;
	dst = kmalloc(len, GFP_KERNEL);
	if (!dst)
	return NULL;
	strlcpy(dst, src, len);
	}

	return dst;
	}

	static __le16 convert_to_sfu_char(char src_char)
	{
	__le16 dest_char;

	switch (src_char) {
	case ':':
	dest_char = cpu_to_le16(UNI_COLON);
	break;
	case '*':
	dest_char = cpu_to_le16(UNI_ASTERISK);
	break;
	case '?':
	dest_char = cpu_to_le16(UNI_QUESTION);
	break;
	case '<':
	dest_char = cpu_to_le16(UNI_LESSTHAN);
	break;
	case '>':
	dest_char = cpu_to_le16(UNI_GRTRTHAN);
	break;
	case '\|':
	dest_char = cpu_to_le16(UNI_PIPE);
	break;
	default:
	dest_char = 0;
	}

	return dest_char;
	}

	static __le16 convert_to_sfm_char(char src_char, bool end_of_string)
	{
	__le16 dest_char;

	switch (src_char) {
	case ':':
	dest_char = cpu_to_le16(SFM_COLON);
	break;
	case '*':
	dest_char = cpu_to_le16(SFM_ASTERISK);
	break;
	case '?':
	dest_char = cpu_to_le16(SFM_QUESTION);
	break;
	case '<':
	dest_char = cpu_to_le16(SFM_LESSTHAN);
	break;
	case '>':
	dest_char = cpu_to_le16(SFM_GRTRTHAN);
	break;
	case '\|':
	dest_char = cpu_to_le16(SFM_PIPE);
	break;
	case '.':
	if (end_of_string)
	dest_char = cpu_to_le16(SFM_PERIOD);
	else
	dest_char = 0;
	break;
	case ' ':
	if (end_of_string)
	dest_char = cpu_to_le16(SFM_SPACE);
	else
	dest_char = 0;
	break;
	default:
	dest_char = 0;
	}

	return dest_char;
	}

	/*
	* Convert 16 bit Unicode pathname to wire format from string in current code
	* page. Conversion may involve remapping up the six characters that are
	* only legal in POSIX-like OS (if they are present in the string). Path
	* names are little endian 16 bit Unicode on the wire
	*/
	int
	cifsConvertToUTF16(__le16 target, const char source, int srclen,
	const struct nls_table *cp, int map_chars)
	{
	int i, charlen;
	int j = 0;
	char src_char;
	__le16 dst_char;
	wchar_t tmp;
	wchar_t wchar_to; / UTF-16 */
	int ret;
	unicode_t u;

	if (map_chars == NO_MAP_UNI_RSVD)
	return cifs_strtoUTF16(target, source, PATH_MAX, cp);

	wchar_to = kzalloc(6, GFP_KERNEL);

	for (i = 0; i < srclen; j++) {
	src_char = source[i];
	charlen = 1;

	/* check if end of string */
	if (src_char == 0)
	goto ctoUTF16_out;

	/* see if we must remap this char */
	if (map_chars == SFU_MAP_UNI_RSVD)
	dst_char = convert_to_sfu_char(src_char);
	else if (map_chars == SFM_MAP_UNI_RSVD) {
	bool end_of_string;

	if (i == srclen - 1)
	end_of_string = true;
	else
	end_of_string = false;

	dst_char = convert_to_sfm_char(src_char, end_of_string);
	} else
	dst_char = 0;
	/*
	* FIXME: We can not handle remapping backslash (UNI_SLASH)
	* until all the calls to build_path_from_dentry are modified,
	* as they use backslash as separator.
	*/
	if (dst_char == 0) {
	charlen = cp->char2uni(source + i, srclen - i, &tmp);
	dst_char = cpu_to_le16(tmp);

	/*
	* if no match, use question mark, which at least in
	* some cases serves as wild card
	*/
	if (charlen > 0)
	goto ctoUTF16;

	/* convert SURROGATE_PAIR */
	if (strcmp(cp->charset, "utf8") \|\| !wchar_to)
	goto unknown;
	if (*(source + i) & 0x80) {
	charlen = utf8_to_utf32(source + i, 6, &u);
	if (charlen < 0)
	goto unknown;
	} else
	goto unknown;
	ret = utf8s_to_utf16s(source + i, charlen,
	UTF16_LITTLE_ENDIAN,
	wchar_to, 6);
	if (ret < 0)
	goto unknown;

	i += charlen;
	dst_char = cpu_to_le16(*wchar_to);
	if (charlen <= 3)
	/* 1-3bytes UTF-8 to 2bytes UTF-16 */
	put_unaligned(dst_char, &target[j]);
	else if (charlen == 4) {
	/* 4bytes UTF-8(surrogate pair) to 4bytes UTF-16
	* 7-8bytes UTF-8(IVS) divided to 2 UTF-16
	* (charlen=3+4 or 4+4) */
	put_unaligned(dst_char, &target[j]);
	dst_char = cpu_to_le16(*(wchar_to + 1));
	j++;
	put_unaligned(dst_char, &target[j]);
	} else if (charlen >= 5) {
	/* 5-6bytes UTF-8 to 6bytes UTF-16 */
	put_unaligned(dst_char, &target[j]);
	dst_char = cpu_to_le16(*(wchar_to + 1));
	j++;
	put_unaligned(dst_char, &target[j]);
	dst_char = cpu_to_le16(*(wchar_to + 2));
	j++;
	put_unaligned(dst_char, &target[j]);
	}
	continue;

	unknown:
	dst_char = cpu_to_le16(0x003f);
	charlen = 1;
	}

	ctoUTF16:
	/*
	* character may take more than one byte in the source string,
	* but will take exactly two bytes in the target string
	*/
	i += charlen;
	put_unaligned(dst_char, &target[j]);
	}

	ctoUTF16_out:
	put_unaligned(0, &target[j]); /* Null terminate target unicode string */
	kfree(wchar_to);
	return j;
	}

	#ifdef CONFIG_CIFS_SMB2
	/*
	* cifs_local_to_utf16_bytes - how long will a string be after conversion?
	* @from - pointer to input string
	* @maxbytes - don't go past this many bytes of input string
	* @codepage - source codepage
	*
	* Walk a string and return the number of bytes that the string will
	* be after being converted to the given charset, not including any null
	* termination required. Don't walk past maxbytes in the source buffer.
	*/

	static int
	cifs_local_to_utf16_bytes(const char *from, int len,
	const struct nls_table *codepage)
	{
	int charlen;
	int i;
	wchar_t wchar_to;

	for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
	charlen = codepage->char2uni(from, len, &wchar_to);
	/* Failed conversion defaults to a question mark */
	if (charlen < 1)
	charlen = 1;
	}
	return 2 * i; /* UTF16 characters are two bytes */
	}

	/*
	* cifs_strndup_to_utf16 - copy a string to wire format from the local codepage
	* @src - source string
	* @maxlen - don't walk past this many bytes in the source string
	* @utf16_len - the length of the allocated string in bytes (including null)
	* @cp - source codepage
	* @remap - map special chars
	*
	* Take a string convert it from the local codepage to UTF16 and
	* put it in a new buffer. Returns a pointer to the new string or NULL on
	* error.
	*/
	__le16 *
	cifs_strndup_to_utf16(const char src, const int maxlen, int utf16_len,
	const struct nls_table *cp, int remap)
	{
	int len;
	__le16 *dst;

	len = cifs_local_to_utf16_bytes(src, maxlen, cp);
	len += 2; /* NULL */
	dst = kmalloc(len, GFP_KERNEL);
	if (!dst) {
	*utf16_len = 0;
	return NULL;
	}
	cifsConvertToUTF16(dst, src, strlen(src), cp, remap);
	*utf16_len = len;
	return dst;
	}
	#endif /* CONFIG_CIFS_SMB2 */