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/vendor/pcre/pcre_try_flipped.c

http://github.com/feyeleanor/RubyGoLightly
C | 137 lines | 45 code | 19 blank | 73 comment | 6 complexity | 81c8770560d927561163d36a265bcf1a MD5 | raw file
  1/*************************************************
  2*      Perl-Compatible Regular Expressions       *
  3*************************************************/
  4
  5/* PCRE is a library of functions to support regular expressions whose syntax
  6and semantics are as close as possible to those of the Perl 5 language.
  7
  8                       Written by Philip Hazel
  9           Copyright (c) 1997-2008 University of Cambridge
 10
 11-----------------------------------------------------------------------------
 12Redistribution and use in source and binary forms, with or without
 13modification, 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
 26THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 27AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 28IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 29ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 30LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 31CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 32SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 33INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 34CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 35ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 36POSSIBILITY OF SUCH DAMAGE.
 37-----------------------------------------------------------------------------
 38*/
 39
 40
 41/* This module contains an internal function that tests a compiled pattern to
 42see if it was compiled with the opposite endianness. If so, it uses an
 43auxiliary local function to flip the appropriate bytes. */
 44
 45
 46#ifdef HAVE_CONFIG_H
 47#include "config.h"
 48#endif
 49
 50#include "pcre_internal.h"
 51
 52
 53/*************************************************
 54*         Flip bytes in an integer               *
 55*************************************************/
 56
 57/* This function is called when the magic number in a regex doesn't match, in
 58order to flip its bytes to see if we are dealing with a pattern that was
 59compiled on a host of different endianness. If so, this function is used to
 60flip other byte values.
 61
 62Arguments:
 63  value        the number to flip
 64  n            the number of bytes to flip (assumed to be 2 or 4)
 65
 66Returns:       the flipped value
 67*/
 68
 69static unsigned long int
 70byteflip(unsigned long int value, int n)
 71{
 72if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);
 73return ((value & 0x000000ff) << 24) |
 74       ((value & 0x0000ff00) <<  8) |
 75       ((value & 0x00ff0000) >>  8) |
 76       ((value & 0xff000000) >> 24);
 77}
 78
 79
 80
 81/*************************************************
 82*       Test for a byte-flipped compiled regex   *
 83*************************************************/
 84
 85/* This function is called from pcre_exec(), pcre_dfa_exec(), and also from
 86pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that
 87is, it was compiled on a system of opposite endianness. The function is called
 88only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped,
 89we flip all the relevant values into a different data block, and return it.
 90
 91Arguments:
 92  re               points to the regex
 93  study            points to study data, or NULL
 94  internal_re      points to a new regex block
 95  internal_study   points to a new study block
 96
 97Returns:           the new block if is is indeed a byte-flipped regex
 98                   NULL if it is not
 99*/
100
101real_pcre *
102_pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,
103  const pcre_study_data *study, pcre_study_data *internal_study)
104{
105if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
106  return NULL;
107
108*internal_re = *re;           /* To copy other fields */
109internal_re->size = byteflip(re->size, sizeof(re->size));
110internal_re->options = byteflip(re->options, sizeof(re->options));
111internal_re->flags = (pcre_uint16)byteflip(re->flags, sizeof(re->flags));
112internal_re->top_bracket =
113  (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket));
114internal_re->top_backref =
115  (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref));
116internal_re->first_byte =
117  (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte));
118internal_re->req_byte =
119  (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte));
120internal_re->name_table_offset =
121  (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset));
122internal_re->name_entry_size =
123  (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size));
124internal_re->name_count =
125  (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count));
126
127if (study != NULL)
128  {
129  *internal_study = *study;   /* To copy other fields */
130  internal_study->size = byteflip(study->size, sizeof(study->size));
131  internal_study->options = byteflip(study->options, sizeof(study->options));
132  }
133
134return internal_re;
135}
136
137/* End of pcre_tryflipped.c */