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 <linux/slab.h>
  23 #include "cifs_unicode.h"
  24 #include "cifs_uniupr.h"
  25 #include "cifspdu.h"
  26 #include "cifsglob.h"
  27 #include "cifs_debug.h"
  28
  29 /*
  30  * cifs_ucs2_bytes - how long will a string be after conversion?
  31  * @ucs - pointer to input string
  32  * @maxbytes - don't go past this many bytes of input string
  33  * @codepage - destination codepage
  34  *
  35  * Walk a ucs2le string and return the number of bytes that the string will
  36  * be after being converted to the given charset, not including any null
  37  * termination required. Don't walk past maxbytes in the source buffer.
  38  */
  39 int
  40 cifs_ucs2_bytes(const __le16 *from, int maxbytes,
  41                 const struct nls_table *codepage)
  42 {
  43         int i;
  44         int charlen, outlen = 0;
  45         int maxwords = maxbytes / 2;
  46         char tmp[NLS_MAX_CHARSET_SIZE];
  47
  48         for (i = 0; i < maxwords && from[i]; i++) {
  49                 charlen = codepage->uni2char(le16_to_cpu(from[i]), tmp,
  50                                              NLS_MAX_CHARSET_SIZE);
  51                 if (charlen > 0)
  52                         outlen += charlen;
  53                 else
  54                         outlen++;
  55         }
  56
  57         return outlen;
  58 }
  59
  60 /*
  61  * cifs_mapchar - convert a little-endian char to proper char in codepage
  62  * @target - where converted character should be copied
  63  * @src_char - 2 byte little-endian source character
  64  * @cp - codepage to which character should be converted
  65  * @mapchar - should character be mapped according to mapchars mount option?
  66  *
  67  * This function handles the conversion of a single character. It is the
  68  * responsibility of the caller to ensure that the target buffer is large
  69  * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
  70  */
  71 static int
  72 cifs_mapchar(char *target, const __le16 src_char, const struct nls_table *cp,
  73              bool mapchar)
  74 {
  75         int len = 1;
  76
  77         if (!mapchar)
  78                 goto cp_convert;
  79
  80         /*
  81          * BB: Cannot handle remapping UNI_SLASH until all the calls to
  82          *     build_path_from_dentry are modified, as they use slash as
  83          *     separator.
  84          */
  85         switch (le16_to_cpu(src_char)) {
  86         case UNI_COLON:
  87                 *target = ':';
  88                 break;
  89         case UNI_ASTERIK:
  90                 *target = '*';
  91                 break;
  92         case UNI_QUESTION:
  93                 *target = '?';
  94                 break;
  95         case UNI_PIPE:
  96                 *target = '|';
  97                 break;
  98         case UNI_GRTRTHAN:
  99                 *target = '>';
 100                 break;
 101         case UNI_LESSTHAN:
 102                 *target = '<';
 103                 break;
 104         default:
 105                 goto cp_convert;
 106         }
 107
 108 out:
 109         return len;
 110
 111 cp_convert:
 112         len = cp->uni2char(le16_to_cpu(src_char), target,
 113                            NLS_MAX_CHARSET_SIZE);
 114         if (len <= 0) {
 115                 *target = '?';
 116                 len = 1;
 117         }
 118         goto out;
 119 }
 120
 121 /*
 122  * cifs_from_ucs2 - convert utf16le string to local charset
 123  * @to - destination buffer
 124  * @from - source buffer
 125  * @tolen - destination buffer size (in bytes)
 126  * @fromlen - source buffer size (in bytes)
 127  * @codepage - codepage to which characters should be converted
 128  * @mapchar - should characters be remapped according to the mapchars option?
 129  *
 130  * Convert a little-endian ucs2le string (as sent by the server) to a string
 131  * in the provided codepage. The tolen and fromlen parameters are to ensure
 132  * that the code doesn't walk off of the end of the buffer (which is always
 133  * a danger if the alignment of the source buffer is off). The destination
 134  * string is always properly null terminated and fits in the destination
 135  * buffer. Returns the length of the destination string in bytes (including
 136  * null terminator).
 137  *
 138  * Note that some windows versions actually send multiword UTF-16 characters
 139  * instead of straight UCS-2. The linux nls routines however aren't able to
 140  * deal with those characters properly. In the event that we get some of
 141  * those characters, they won't be translated properly.
 142  */
 143 int
 144 cifs_from_ucs2(char *to, const __le16 *from, int tolen, int fromlen,
 145                  const struct nls_table *codepage, bool mapchar)
 146 {
 147         int i, charlen, safelen;
 148         int outlen = 0;
 149         int nullsize = nls_nullsize(codepage);
 150         int fromwords = fromlen / 2;
 151         char tmp[NLS_MAX_CHARSET_SIZE];
 152
 153         /*
 154          * because the chars can be of varying widths, we need to take care
 155          * not to overflow the destination buffer when we get close to the
 156          * end of it. Until we get to this offset, we don't need to check
 157          * for overflow however.
 158          */
 159         safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);
 160
 161         for (i = 0; i < fromwords && from[i]; i++) {
 162                 /*
 163                  * check to see if converting this character might make the
 164                  * conversion bleed into the null terminator
 165                  */
 166                 if (outlen >= safelen) {
 167                         charlen = cifs_mapchar(tmp, from[i], codepage, mapchar);
 168                         if ((outlen + charlen) > (tolen - nullsize))
 169                                 break;
 170                 }
 171
 172                 /* put converted char into 'to' buffer */
 173                 charlen = cifs_mapchar(&to[outlen], from[i], codepage, mapchar);
 174                 outlen += charlen;
 175         }
 176
 177         /* properly null-terminate string */
 178         for (i = 0; i < nullsize; i++)
 179                 to[outlen++] = 0;
 180
 181         return outlen;
 182 }
 183
 184 /*
 185  * NAME:        cifs_strtoUCS()
 186  *
 187  * FUNCTION:    Convert character string to unicode string
 188  *
 189  */
 190 int
 191 cifs_strtoUCS(__le16 *to, const char *from, int len,
 192               const struct nls_table *codepage)
 193 {
 194         int charlen;
 195         int i;
 196         wchar_t *wchar_to = (wchar_t *)to; /* needed to quiet sparse */
 197
 198         for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
 199
 200                 /* works for 2.4.0 kernel or later */
 201                 charlen = codepage->char2uni(from, len, &wchar_to[i]);
 202                 if (charlen < 1) {
 203                         cERROR(1,
 204                                ("strtoUCS: char2uni of %d returned %d",
 205                                 (int)*from, charlen));
 206                         /* A question mark */
 207                         to[i] = cpu_to_le16(0x003f);
 208                         charlen = 1;
 209                 } else
 210                         to[i] = cpu_to_le16(wchar_to[i]);
 211
 212         }
 213
 214         to[i] = 0;
 215         return i;
 216 }
 217
 218 /*
 219  * cifs_strndup_from_ucs - copy a string from wire format to the local codepage
 220  * @src - source string
 221  * @maxlen - don't walk past this many bytes in the source string
 222  * @is_unicode - is this a unicode string?
 223  * @codepage - destination codepage
 224  *
 225  * Take a string given by the server, convert it to the local codepage and
 226  * put it in a new buffer. Returns a pointer to the new string or NULL on
 227  * error.
 228  */
 229 char *
 230 cifs_strndup_from_ucs(const char *src, const int maxlen, const bool is_unicode,
 231              const struct nls_table *codepage)
 232 {
 233         int len;
 234         char *dst;
 235
 236         if (is_unicode) {
 237                 len = cifs_ucs2_bytes((__le16 *) src, maxlen, codepage);
 238                 len += nls_nullsize(codepage);
 239                 dst = kmalloc(len, GFP_KERNEL);
 240                 if (!dst)
 241                         return NULL;
 242                 cifs_from_ucs2(dst, (__le16 *) src, len, maxlen, codepage,
 243                                false);
 244         } else {
 245                 len = strnlen(src, maxlen);
 246                 len++;
 247                 dst = kmalloc(len, GFP_KERNEL);
 248                 if (!dst)
 249                         return NULL;
 250                 strlcpy(dst, src, len);
 251         }
 252
 253         return dst;
 254 }
 255