/*************************************************

*      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) 1997-2005 University of Cambridge

-----------------------------------------------------------------------------

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,

      this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

      notice, this list of conditions and the following disclaimer in the

      documentation and/or other materials provided with the distribution.

    * Neither the name of the University of Cambridge nor the names of its

      contributors may be used to endorse or promote products derived from

      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

-----------------------------------------------------------------------------

*/

/* This module contains an internal function that tests a compiled pattern to

see if it was compiled with the opposite endianness. If so, it uses an

auxiliary local function to flip the appropriate bytes. */

#include "pcre_internal.h"

/*************************************************

*         Flip bytes in an integer               *

*************************************************/

/* This function is called when the magic number in a regex doesn't match, in

order to flip its bytes to see if we are dealing with a pattern that was

compiled on a host of different endianness. If so, this function is used to

flip other byte values.

Arguments:

  value        the number to flip

  n            the number of bytes to flip (assumed to be 2 or 4)

Returns:       the flipped value

*/

static long int

byteflip(long int value, int n)

{

if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);

return ((value & 0x000000ff) << 24) |

       ((value & 0x0000ff00) <<  8) |

       ((value & 0x00ff0000) >>  8) |

       ((value & 0xff000000) >> 24);

}

/*************************************************

*       Test for a byte-flipped compiled regex   *

*************************************************/

/* This function is called from pcre_exec(), pcre_dfa_exec(), and also from

pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that

is, it was compiled on a system of opposite endianness. The function is called

only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped,

we flip all the relevant values into a different data block, and return it.

Arguments:

  re               points to the regex

  study            points to study data, or NULL

  internal_re      points to a new regex block

  internal_study   points to a new study block

Returns:           the new block if is is indeed a byte-flipped regex

                   NULL if it is not

*/

PCRE_EXPORT real_pcre *

_pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,

  const pcre_study_data *study, pcre_study_data *internal_study)

{

if (byteflip(re->magic_number, (int)sizeof(re->magic_number)) != MAGIC_NUMBER)

  return NULL;

*internal_re = *re;           /* To copy other fields */

internal_re->size = (pcre_uint32)byteflip(re->size, (int)sizeof(re->size));

internal_re->options = (pcre_uint32)byteflip(re->options, (int)sizeof(re->options));

internal_re->top_bracket =

  (pcre_uint16)byteflip(re->top_bracket, (int)sizeof(re->top_bracket));

internal_re->top_backref =

  (pcre_uint16)byteflip(re->top_backref, (int)sizeof(re->top_backref));

internal_re->first_byte =

  (pcre_uint16)byteflip(re->first_byte, (int)sizeof(re->first_byte));

internal_re->req_byte =

  (pcre_uint16)byteflip(re->req_byte, (int)sizeof(re->req_byte));

internal_re->name_table_offset =

  (pcre_uint16)byteflip(re->name_table_offset, (int)sizeof(re->name_table_offset));

internal_re->name_entry_size =

  (pcre_uint16)byteflip(re->name_entry_size, (int)sizeof(re->name_entry_size));

internal_re->name_count =

  (pcre_uint16)byteflip(re->name_count, (int)sizeof(re->name_count));

if (study != NULL)

  {

  *internal_study = *study;   /* To copy other fields */

  internal_study->size = (pcre_uint32)byteflip(study->size, (int)sizeof(study->size));

  internal_study->options = (pcre_uint32)byteflip(study->options, (int)sizeof(study->options));

  }

return internal_re;

}

/* End of pcre_tryflipped.c */