glib/pcre/pcre_valid_utf8.c

   1 /*************************************************
   2 *      Perl-Compatible Regular Expressions       *
   3 *************************************************/
   4
   5 /* PCRE is a library of functions to support regular expressions whose syntax
   6 and semantics are as close as possible to those of the Perl 5 language.
   7
   8                        Written by Philip Hazel
   9            Copyright (c) 1997-2012 University of Cambridge
  10
  11 -----------------------------------------------------------------------------
  12 Redistribution and use in source and binary forms, with or without
  13 modification, are permitted provided that the following conditions are met:
  14
  15     * Redistributions of source code must retain the above copyright notice,
  16       this list of conditions and the following disclaimer.
  17
  18     * Redistributions in binary form must reproduce the above copyright
  19       notice, this list of conditions and the following disclaimer in the
  20       documentation and/or other materials provided with the distribution.
  21
  22     * Neither the name of the University of Cambridge nor the names of its
  23       contributors may be used to endorse or promote products derived from
  24       this software without specific prior written permission.
  25
  26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  36 POSSIBILITY OF SUCH DAMAGE.
  37 -----------------------------------------------------------------------------
  38 */
  39
  40
  41 /* This module contains an internal function for validating UTF-8 character
  42 strings. */
  43
  44
  45 #ifdef HAVE_CONFIG_H
  46 #include "config.h"
  47 #endif
  48
  49 #include "pcre_internal.h"
  50
  51
  52 /*************************************************
  53 *         Validate a UTF-8 string                *
  54 *************************************************/
  55
  56 /* This function is called (optionally) at the start of compile or match, to
  57 check that a supposed UTF-8 string is actually valid. The early check means
  58 that subsequent code can assume it is dealing with a valid string. The check
  59 can be turned off for maximum performance, but the consequences of supplying an
  60 invalid string are then undefined.
  61
  62 Originally, this function checked according to RFC 2279, allowing for values in
  63 the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
  64 the canonical format. Once somebody had pointed out RFC 3629 to me (it
  65 obsoletes 2279), additional restrictions were applied. The values are now
  66 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
  67 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
  68 characters is still checked.
  69
  70 From release 8.13 more information about the details of the error are passed
  71 back in the returned value:
  72
  73 PCRE_UTF8_ERR0   No error
  74 PCRE_UTF8_ERR1   Missing 1 byte at the end of the string
  75 PCRE_UTF8_ERR2   Missing 2 bytes at the end of the string
  76 PCRE_UTF8_ERR3   Missing 3 bytes at the end of the string
  77 PCRE_UTF8_ERR4   Missing 4 bytes at the end of the string
  78 PCRE_UTF8_ERR5   Missing 5 bytes at the end of the string
  79 PCRE_UTF8_ERR6   2nd-byte's two top bits are not 0x80
  80 PCRE_UTF8_ERR7   3rd-byte's two top bits are not 0x80
  81 PCRE_UTF8_ERR8   4th-byte's two top bits are not 0x80
  82 PCRE_UTF8_ERR9   5th-byte's two top bits are not 0x80
  83 PCRE_UTF8_ERR10  6th-byte's two top bits are not 0x80
  84 PCRE_UTF8_ERR11  5-byte character is not permitted by RFC 3629
  85 PCRE_UTF8_ERR12  6-byte character is not permitted by RFC 3629
  86 PCRE_UTF8_ERR13  4-byte character with value > 0x10ffff is not permitted
  87 PCRE_UTF8_ERR14  3-byte character with value 0xd000-0xdfff is not permitted
  88 PCRE_UTF8_ERR15  Overlong 2-byte sequence
  89 PCRE_UTF8_ERR16  Overlong 3-byte sequence
  90 PCRE_UTF8_ERR17  Overlong 4-byte sequence
  91 PCRE_UTF8_ERR18  Overlong 5-byte sequence (won't ever occur)
  92 PCRE_UTF8_ERR19  Overlong 6-byte sequence (won't ever occur)
  93 PCRE_UTF8_ERR20  Isolated 0x80 byte (not within UTF-8 character)
  94 PCRE_UTF8_ERR21  Byte with the illegal value 0xfe or 0xff
  95
  96 Arguments:
  97   string       points to the string
  98   length       length of string, or -1 if the string is zero-terminated
  99   errp         pointer to an error position offset variable
 100
 101 Returns:       = 0    if the string is a valid UTF-8 string
 102                > 0    otherwise, setting the offset of the bad character
 103 */
 104
 105 int
 106 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
 107 {
 108 #ifdef SUPPORT_UTF
 109 PCRE_PUCHAR p;
 110
 111 if (length < 0)
 112   {
 113   for (p = string; *p != 0; p++);
 114   length = (int)(p - string);
 115   }
 116
 117 for (p = string; length-- > 0; p++)
 118   {
 119   int ab, c, d;
 120
 121   c = *p;
 122   if (c < 128) continue;                /* ASCII character */
 123
 124   if (c < 0xc0)                         /* Isolated 10xx xxxx byte */
 125     {
 126     *erroroffset = (int)(p - string);
 127     return PCRE_UTF8_ERR20;
 128     }
 129
 130   if (c >= 0xfe)                        /* Invalid 0xfe or 0xff bytes */
 131     {
 132     *erroroffset = (int)(p - string);
 133     return PCRE_UTF8_ERR21;
 134     }
 135
 136   ab = PRIV(utf8_table4)[c & 0x3f];     /* Number of additional bytes */
 137   if (length < ab)
 138     {
 139     *erroroffset = (int)(p - string);          /* Missing bytes */
 140     return ab - length;                 /* Codes ERR1 to ERR5 */
 141     }
 142   length -= ab;                         /* Length remaining */
 143
 144   /* Check top bits in the second byte */
 145
 146   if (((d = *(++p)) & 0xc0) != 0x80)
 147     {
 148     *erroroffset = (int)(p - string) - 1;
 149     return PCRE_UTF8_ERR6;
 150     }
 151
 152   /* For each length, check that the remaining bytes start with the 0x80 bit
 153   set and not the 0x40 bit. Then check for an overlong sequence, and for the
 154   excluded range 0xd800 to 0xdfff. */
 155
 156   switch (ab)
 157     {
 158     /* 2-byte character. No further bytes to check for 0x80. Check first byte
 159     for for xx00 000x (overlong sequence). */
 160
 161     case 1: if ((c & 0x3e) == 0)
 162       {
 163       *erroroffset = (int)(p - string) - 1;
 164       return PCRE_UTF8_ERR15;
 165       }
 166     break;
 167
 168     /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
 169       for 1110 0000, xx0x xxxx (overlong sequence) or
 170           1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
 171
 172     case 2:
 173     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 174       {
 175       *erroroffset = (int)(p - string) - 2;
 176       return PCRE_UTF8_ERR7;
 177       }
 178     if (c == 0xe0 && (d & 0x20) == 0)
 179       {
 180       *erroroffset = (int)(p - string) - 2;
 181       return PCRE_UTF8_ERR16;
 182       }
 183     if (c == 0xed && d >= 0xa0)
 184       {
 185       *erroroffset = (int)(p - string) - 2;
 186       return PCRE_UTF8_ERR14;
 187       }
 188     break;
 189
 190     /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
 191        bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
 192        character greater than 0x0010ffff (f4 8f bf bf) */
 193
 194     case 3:
 195     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 196       {
 197       *erroroffset = (int)(p - string) - 2;
 198       return PCRE_UTF8_ERR7;
 199       }
 200     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 201       {
 202       *erroroffset = (int)(p - string) - 3;
 203       return PCRE_UTF8_ERR8;
 204       }
 205     if (c == 0xf0 && (d & 0x30) == 0)
 206       {
 207       *erroroffset = (int)(p - string) - 3;
 208       return PCRE_UTF8_ERR17;
 209       }
 210     if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
 211       {
 212       *erroroffset = (int)(p - string) - 3;
 213       return PCRE_UTF8_ERR13;
 214       }
 215     break;
 216
 217     /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
 218     rejected by the length test below. However, we do the appropriate tests
 219     here so that overlong sequences get diagnosed, and also in case there is
 220     ever an option for handling these larger code points. */
 221
 222     /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
 223     1111 1000, xx00 0xxx */
 224
 225     case 4:
 226     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 227       {
 228       *erroroffset = (int)(p - string) - 2;
 229       return PCRE_UTF8_ERR7;
 230       }
 231     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 232       {
 233       *erroroffset = (int)(p - string) - 3;
 234       return PCRE_UTF8_ERR8;
 235       }
 236     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
 237       {
 238       *erroroffset = (int)(p - string) - 4;
 239       return PCRE_UTF8_ERR9;
 240       }
 241     if (c == 0xf8 && (d & 0x38) == 0)
 242       {
 243       *erroroffset = (int)(p - string) - 4;
 244       return PCRE_UTF8_ERR18;
 245       }
 246     break;
 247
 248     /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
 249     1111 1100, xx00 00xx. */
 250
 251     case 5:
 252     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 253       {
 254       *erroroffset = (int)(p - string) - 2;
 255       return PCRE_UTF8_ERR7;
 256       }
 257     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 258       {
 259       *erroroffset = (int)(p - string) - 3;
 260       return PCRE_UTF8_ERR8;
 261       }
 262     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
 263       {
 264       *erroroffset = (int)(p - string) - 4;
 265       return PCRE_UTF8_ERR9;
 266       }
 267     if ((*(++p) & 0xc0) != 0x80)     /* Sixth byte */
 268       {
 269       *erroroffset = (int)(p - string) - 5;
 270       return PCRE_UTF8_ERR10;
 271       }
 272     if (c == 0xfc && (d & 0x3c) == 0)
 273       {
 274       *erroroffset = (int)(p - string) - 5;
 275       return PCRE_UTF8_ERR19;
 276       }
 277     break;
 278     }
 279
 280   /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
 281   excluded by RFC 3629. The pointer p is currently at the last byte of the
 282   character. */
 283
 284   if (ab > 3)
 285     {
 286     *erroroffset = (int)(p - string) - ab;
 287     return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
 288     }
 289   }
 290
 291 #else  /* SUPPORT_UTF */
 292 (void)(string);  /* Keep picky compilers happy */
 293 (void)(length);
 294 #endif
 295
 296 return PCRE_UTF8_ERR0;   /* This indicates success */
 297 }
 298
 299 /* End of pcre_valid_utf8.c */