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 #include "config.h"
  46
  47 #include "pcre_internal.h"
  48
  49
  50 /*************************************************
  51 *         Validate a UTF-8 string                *
  52 *************************************************/
  53
  54 /* This function is called (optionally) at the start of compile or match, to
  55 check that a supposed UTF-8 string is actually valid. The early check means
  56 that subsequent code can assume it is dealing with a valid string. The check
  57 can be turned off for maximum performance, but the consequences of supplying an
  58 invalid string are then undefined.
  59
  60 Originally, this function checked according to RFC 2279, allowing for values in
  61 the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
  62 the canonical format. Once somebody had pointed out RFC 3629 to me (it
  63 obsoletes 2279), additional restrictions were applied. The values are now
  64 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
  65 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
  66 characters is still checked.
  67
  68 From release 8.13 more information about the details of the error are passed
  69 back in the returned value:
  70
  71 PCRE_UTF8_ERR0   No error
  72 PCRE_UTF8_ERR1   Missing 1 byte at the end of the string
  73 PCRE_UTF8_ERR2   Missing 2 bytes at the end of the string
  74 PCRE_UTF8_ERR3   Missing 3 bytes at the end of the string
  75 PCRE_UTF8_ERR4   Missing 4 bytes at the end of the string
  76 PCRE_UTF8_ERR5   Missing 5 bytes at the end of the string
  77 PCRE_UTF8_ERR6   2nd-byte's two top bits are not 0x80
  78 PCRE_UTF8_ERR7   3rd-byte's two top bits are not 0x80
  79 PCRE_UTF8_ERR8   4th-byte's two top bits are not 0x80
  80 PCRE_UTF8_ERR9   5th-byte's two top bits are not 0x80
  81 PCRE_UTF8_ERR10  6th-byte's two top bits are not 0x80
  82 PCRE_UTF8_ERR11  5-byte character is not permitted by RFC 3629
  83 PCRE_UTF8_ERR12  6-byte character is not permitted by RFC 3629
  84 PCRE_UTF8_ERR13  4-byte character with value > 0x10ffff is not permitted
  85 PCRE_UTF8_ERR14  3-byte character with value 0xd000-0xdfff is not permitted
  86 PCRE_UTF8_ERR15  Overlong 2-byte sequence
  87 PCRE_UTF8_ERR16  Overlong 3-byte sequence
  88 PCRE_UTF8_ERR17  Overlong 4-byte sequence
  89 PCRE_UTF8_ERR18  Overlong 5-byte sequence (won't ever occur)
  90 PCRE_UTF8_ERR19  Overlong 6-byte sequence (won't ever occur)
  91 PCRE_UTF8_ERR20  Isolated 0x80 byte (not within UTF-8 character)
  92 PCRE_UTF8_ERR21  Byte with the illegal value 0xfe or 0xff
  93
  94 Arguments:
  95   string       points to the string
  96   length       length of string, or -1 if the string is zero-terminated
  97   errp         pointer to an error position offset variable
  98
  99 Returns:       = 0    if the string is a valid UTF-8 string
 100                > 0    otherwise, setting the offset of the bad character
 101 */
 102
 103 int
 104 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
 105 {
 106 #ifdef SUPPORT_UTF
 107 PCRE_PUCHAR p;
 108
 109 if (length < 0)
 110   {
 111   for (p = string; *p != 0; p++);
 112   length = (int)(p - string);
 113   }
 114
 115 for (p = string; length-- > 0; p++)
 116   {
 117   int ab, c, d;
 118
 119   c = *p;
 120   if (c < 128) continue;                /* ASCII character */
 121
 122   if (c < 0xc0)                         /* Isolated 10xx xxxx byte */
 123     {
 124     *erroroffset = (int)(p - string);
 125     return PCRE_UTF8_ERR20;
 126     }
 127
 128   if (c >= 0xfe)                        /* Invalid 0xfe or 0xff bytes */
 129     {
 130     *erroroffset = (int)(p - string);
 131     return PCRE_UTF8_ERR21;
 132     }
 133
 134   ab = PRIV(utf8_table4)[c & 0x3f];     /* Number of additional bytes */
 135   if (length < ab)
 136     {
 137     *erroroffset = (int)(p - string);          /* Missing bytes */
 138     return ab - length;                 /* Codes ERR1 to ERR5 */
 139     }
 140   length -= ab;                         /* Length remaining */
 141
 142   /* Check top bits in the second byte */
 143
 144   if (((d = *(++p)) & 0xc0) != 0x80)
 145     {
 146     *erroroffset = (int)(p - string) - 1;
 147     return PCRE_UTF8_ERR6;
 148     }
 149
 150   /* For each length, check that the remaining bytes start with the 0x80 bit
 151   set and not the 0x40 bit. Then check for an overlong sequence, and for the
 152   excluded range 0xd800 to 0xdfff. */
 153
 154   switch (ab)
 155     {
 156     /* 2-byte character. No further bytes to check for 0x80. Check first byte
 157     for for xx00 000x (overlong sequence). */
 158
 159     case 1: if ((c & 0x3e) == 0)
 160       {
 161       *erroroffset = (int)(p - string) - 1;
 162       return PCRE_UTF8_ERR15;
 163       }
 164     break;
 165
 166     /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
 167       for 1110 0000, xx0x xxxx (overlong sequence) or
 168           1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
 169
 170     case 2:
 171     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 172       {
 173       *erroroffset = (int)(p - string) - 2;
 174       return PCRE_UTF8_ERR7;
 175       }
 176     if (c == 0xe0 && (d & 0x20) == 0)
 177       {
 178       *erroroffset = (int)(p - string) - 2;
 179       return PCRE_UTF8_ERR16;
 180       }
 181     if (c == 0xed && d >= 0xa0)
 182       {
 183       *erroroffset = (int)(p - string) - 2;
 184       return PCRE_UTF8_ERR14;
 185       }
 186     break;
 187
 188     /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
 189        bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
 190        character greater than 0x0010ffff (f4 8f bf bf) */
 191
 192     case 3:
 193     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 194       {
 195       *erroroffset = (int)(p - string) - 2;
 196       return PCRE_UTF8_ERR7;
 197       }
 198     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 199       {
 200       *erroroffset = (int)(p - string) - 3;
 201       return PCRE_UTF8_ERR8;
 202       }
 203     if (c == 0xf0 && (d & 0x30) == 0)
 204       {
 205       *erroroffset = (int)(p - string) - 3;
 206       return PCRE_UTF8_ERR17;
 207       }
 208     if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
 209       {
 210       *erroroffset = (int)(p - string) - 3;
 211       return PCRE_UTF8_ERR13;
 212       }
 213     break;
 214
 215     /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
 216     rejected by the length test below. However, we do the appropriate tests
 217     here so that overlong sequences get diagnosed, and also in case there is
 218     ever an option for handling these larger code points. */
 219
 220     /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
 221     1111 1000, xx00 0xxx */
 222
 223     case 4:
 224     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 225       {
 226       *erroroffset = (int)(p - string) - 2;
 227       return PCRE_UTF8_ERR7;
 228       }
 229     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 230       {
 231       *erroroffset = (int)(p - string) - 3;
 232       return PCRE_UTF8_ERR8;
 233       }
 234     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
 235       {
 236       *erroroffset = (int)(p - string) - 4;
 237       return PCRE_UTF8_ERR9;
 238       }
 239     if (c == 0xf8 && (d & 0x38) == 0)
 240       {
 241       *erroroffset = (int)(p - string) - 4;
 242       return PCRE_UTF8_ERR18;
 243       }
 244     break;
 245
 246     /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
 247     1111 1100, xx00 00xx. */
 248
 249     case 5:
 250     if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
 251       {
 252       *erroroffset = (int)(p - string) - 2;
 253       return PCRE_UTF8_ERR7;
 254       }
 255     if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
 256       {
 257       *erroroffset = (int)(p - string) - 3;
 258       return PCRE_UTF8_ERR8;
 259       }
 260     if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
 261       {
 262       *erroroffset = (int)(p - string) - 4;
 263       return PCRE_UTF8_ERR9;
 264       }
 265     if ((*(++p) & 0xc0) != 0x80)     /* Sixth byte */
 266       {
 267       *erroroffset = (int)(p - string) - 5;
 268       return PCRE_UTF8_ERR10;
 269       }
 270     if (c == 0xfc && (d & 0x3c) == 0)
 271       {
 272       *erroroffset = (int)(p - string) - 5;
 273       return PCRE_UTF8_ERR19;
 274       }
 275     break;
 276     }
 277
 278   /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
 279   excluded by RFC 3629. The pointer p is currently at the last byte of the
 280   character. */
 281
 282   if (ab > 3)
 283     {
 284     *erroroffset = (int)(p - string) - ab;
 285     return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
 286     }
 287   }
 288
 289 #else  /* SUPPORT_UTF */
 290 (void)(string);  /* Keep picky compilers happy */
 291 (void)(length);
 292 #endif
 293
 294 return PCRE_UTF8_ERR0;   /* This indicates success */
 295 }
 296
 297 /* End of pcre_valid_utf8.c */