pcre32_valid_utf32.c

/*************************************************
*      Perl-Compatible Regular Expressions       *
*************************************************/

/* PCRE is a library of functions to support regular expressions whose syntax
and semantics are as close as possible to those of the Perl 5 language.

                       Written by Philip Hazel
           Copyright (c) 1997-2013 University of Cambridge

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*/


/* This module contains an internal function for validating UTF-32 character
strings. */


#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/* Generate code with 32 bit character support. */
#define COMPILE_PCRE32

#include "pcre_internal.h"

/*************************************************
*         Validate a UTF-32 string                *
*************************************************/

/* This function is called (optionally) at the start of compile or match, to
check that a supposed UTF-32 string is actually valid. The early check means
that subsequent code can assume it is dealing with a valid string. The check
can be turned off for maximum performance, but the consequences of supplying an
invalid string are then undefined.

More information about the details of the error are passed
back in the returned value:

PCRE_UTF32_ERR0  No error
PCRE_UTF32_ERR1  Surrogate character
PCRE_UTF32_ERR2  Unused (was non-character)
PCRE_UTF32_ERR3  Character > 0x10ffff

Arguments:
  string       points to the string
  length       length of string, or -1 if the string is zero-terminated
  errp         pointer to an error position offset variable

Returns:       = 0    if the string is a valid UTF-32 string
               > 0    otherwise, setting the offset of the bad character
*/

int
PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
{
#ifdef SUPPORT_UTF
register PCRE_PUCHAR p;
register pcre_uchar c;

if (length < 0)
  {
  for (p = string; *p != 0; p++);
  length = p - string;
  }

for (p = string; length-- > 0; p++)
  {
  c = *p;

  if ((c & 0xfffff800u) != 0xd800u)
    {
    /* Normal UTF-32 code point. Neither high nor low surrogate. */
    if (c > 0x10ffffu)
      {
      *erroroffset = p - string;
      return PCRE_UTF32_ERR3;
      }
    }
  else
    {
    /* A surrogate */
    *erroroffset = p - string;
    return PCRE_UTF32_ERR1;
    }
  }

#else  /* SUPPORT_UTF */
(void)(string);  /* Keep picky compilers happy */
(void)(length);
(void)(erroroffset);
#endif /* SUPPORT_UTF */

return PCRE_UTF32_ERR0;   /* This indicates success */
}

/* End of pcre32_valid_utf32.c */