fs/cifs/cifs_unicode.c

   1 /*
   2  *   fs/cifs/cifs_unicode.c
   3  *
   4  *   Copyright (c) International Business Machines  Corp., 2000,2009
   5  *   Modified by Steve French (sfrench@us.ibm.com)
   6  *
   7  *   This program is free software;  you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  15  *   the GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program;  if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21 #include <linux/fs.h>
  22 #include "cifs_unicode.h"
  23 #include "cifs_uniupr.h"
  24 #include "cifspdu.h"
  25 #include "cifsglob.h"
  26 #include "cifs_debug.h"
  27
  28 /*
  29  * cifs_ucs2_bytes - how long will a string be after conversion?
  30  * @ucs - pointer to input string
  31  * @maxbytes - don't go past this many bytes of input string
  32  * @codepage - destination codepage
  33  *
  34  * Walk a ucs2le string and return the number of bytes that the string will
  35  * be after being converted to the given charset, not including any null
  36  * termination required. Don't walk past maxbytes in the source buffer.
  37  */
  38 int
  39 cifs_ucs2_bytes(const __le16 *from, int maxbytes,
  40                 const struct nls_table *codepage)
  41 {
  42         int i;
  43         int charlen, outlen = 0;
  44         int maxwords = maxbytes / 2;
  45         char tmp[NLS_MAX_CHARSET_SIZE];
  46
  47         for (i = 0; from[i] && i < maxwords; i++) {
  48                 charlen = codepage->uni2char(le16_to_cpu(from[i]), tmp,
  49                                              NLS_MAX_CHARSET_SIZE);
  50                 if (charlen > 0)
  51                         outlen += charlen;
  52                 else
  53                         outlen++;
  54         }
  55
  56         return outlen;
  57 }
  58
  59 /*
  60  * cifs_mapchar - convert a little-endian char to proper char in codepage
  61  * @target - where converted character should be copied
  62  * @src_char - 2 byte little-endian source character
  63  * @cp - codepage to which character should be converted
  64  * @mapchar - should character be mapped according to mapchars mount option?
  65  *
  66  * This function handles the conversion of a single character. It is the
  67  * responsibility of the caller to ensure that the target buffer is large
  68  * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
  69  */
  70 static int
  71 cifs_mapchar(char *target, const __le16 src_char, const struct nls_table *cp,
  72              bool mapchar)
  73 {
  74         int len = 1;
  75
  76         if (!mapchar)
  77                 goto cp_convert;
  78
  79         /*
  80          * BB: Cannot handle remapping UNI_SLASH until all the calls to
  81          *     build_path_from_dentry are modified, as they use slash as
  82          *     separator.
  83          */
  84         switch (le16_to_cpu(src_char)) {
  85         case UNI_COLON:
  86                 *target = ':';
  87                 break;
  88         case UNI_ASTERIK:
  89                 *target = '*';
  90                 break;
  91         case UNI_QUESTION:
  92                 *target = '?';
  93                 break;
  94         case UNI_PIPE:
  95                 *target = '|';
  96                 break;
  97         case UNI_GRTRTHAN:
  98                 *target = '>';
  99                 break;
 100         case UNI_LESSTHAN:
 101                 *target = '<';
 102                 break;
 103         default:
 104                 goto cp_convert;
 105         }
 106
 107 out:
 108         return len;
 109
 110 cp_convert:
 111         len = cp->uni2char(le16_to_cpu(src_char), target,
 112                            NLS_MAX_CHARSET_SIZE);
 113         if (len <= 0) {
 114                 *target = '?';
 115                 len = 1;
 116         }
 117         goto out;
 118 }
 119
 120 /*
 121  * cifs_from_ucs2 - convert utf16le string to local charset
 122  * @to - destination buffer
 123  * @from - source buffer
 124  * @tolen - destination buffer size (in bytes)
 125  * @fromlen - source buffer size (in bytes)
 126  * @codepage - codepage to which characters should be converted
 127  * @mapchar - should characters be remapped according to the mapchars option?
 128  *
 129  * Convert a little-endian ucs2le string (as sent by the server) to a string
 130  * in the provided codepage. The tolen and fromlen parameters are to ensure
 131  * that the code doesn't walk off of the end of the buffer (which is always
 132  * a danger if the alignment of the source buffer is off). The destination
 133  * string is always properly null terminated and fits in the destination
 134  * buffer. Returns the length of the destination string in bytes (including
 135  * null terminator).
 136  *
 137  * Note that some windows versions actually send multiword UTF-16 characters
 138  * instead of straight UCS-2. The linux nls routines however aren't able to
 139  * deal with those characters properly. In the event that we get some of
 140  * those characters, they won't be translated properly.
 141  */
 142 int
 143 cifs_from_ucs2(char *to, const __le16 *from, int tolen, int fromlen,
 144                  const struct nls_table *codepage, bool mapchar)
 145 {
 146         int i, charlen, safelen;
 147         int outlen = 0;
 148         int nullsize = nls_nullsize(codepage);
 149         int fromwords = fromlen / 2;
 150         char tmp[NLS_MAX_CHARSET_SIZE];
 151
 152         /*
 153          * because the chars can be of varying widths, we need to take care
 154          * not to overflow the destination buffer when we get close to the
 155          * end of it. Until we get to this offset, we don't need to check
 156          * for overflow however.
 157          */
 158         safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);
 159
 160         for (i = 0; i < fromwords && from[i]; i++) {
 161                 /*
 162                  * check to see if converting this character might make the
 163                  * conversion bleed into the null terminator
 164                  */
 165                 if (outlen >= safelen) {
 166                         charlen = cifs_mapchar(tmp, from[i], codepage, mapchar);
 167                         if ((outlen + charlen) > (tolen - nullsize))
 168                                 break;
 169                 }
 170
 171                 /* put converted char into 'to' buffer */
 172                 charlen = cifs_mapchar(&to[outlen], from[i], codepage, mapchar);
 173                 outlen += charlen;
 174         }
 175
 176         /* properly null-terminate string */
 177         for (i = 0; i < nullsize; i++)
 178                 to[outlen++] = 0;
 179
 180         return outlen;
 181 }
 182
 183 /*
 184  * NAME:        cifs_strtoUCS()
 185  *
 186  * FUNCTION:    Convert character string to unicode string
 187  *
 188  */
 189 int
 190 cifs_strtoUCS(__le16 *to, const char *from, int len,
 191               const struct nls_table *codepage)
 192 {
 193         int charlen;
 194         int i;
 195         wchar_t *wchar_to = (wchar_t *)to; /* needed to quiet sparse */
 196
 197         for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
 198
 199                 /* works for 2.4.0 kernel or later */
 200                 charlen = codepage->char2uni(from, len, &wchar_to[i]);
 201                 if (charlen < 1) {
 202                         cERROR(1,
 203                                ("strtoUCS: char2uni of %d returned %d",
 204                                 (int)*from, charlen));
 205                         /* A question mark */
 206                         to[i] = cpu_to_le16(0x003f);
 207                         charlen = 1;
 208                 } else
 209                         to[i] = cpu_to_le16(wchar_to[i]);
 210
 211         }
 212
 213         to[i] = 0;
 214         return i;
 215 }
 216
 217 /*
 218  * cifs_strndup_from_ucs - copy a string from wire format to the local codepage
 219  * @src - source string
 220  * @maxlen - don't walk past this many bytes in the source string
 221  * @is_unicode - is this a unicode string?
 222  * @codepage - destination codepage
 223  *
 224  * Take a string given by the server, convert it to the local codepage and
 225  * put it in a new buffer. Returns a pointer to the new string or NULL on
 226  * error.
 227  */
 228 char *
 229 cifs_strndup_from_ucs(const char *src, const int maxlen, const bool is_unicode,
 230              const struct nls_table *codepage)
 231 {
 232         int len;
 233         char *dst;
 234
 235         if (is_unicode) {
 236                 len = cifs_ucs2_bytes((__le16 *) src, maxlen, codepage);
 237                 len += nls_nullsize(codepage);
 238                 dst = kmalloc(len, GFP_KERNEL);
 239                 if (!dst)
 240                         return NULL;
 241                 cifs_from_ucs2(dst, (__le16 *) src, len, maxlen, codepage,
 242                                false);
 243         } else {
 244                 len = strnlen(src, maxlen);
 245                 len++;
 246                 dst = kmalloc(len, GFP_KERNEL);
 247                 if (!dst)
 248                         return NULL;
 249                 strlcpy(dst, src, len);
 250         }
 251
 252         return dst;
 253 }
 254