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Annotation of embedaddon/pcre/pcre_try_flipped.c, revision 1.1.1.1

1.1       misho       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) 1997-2009 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 that tests a compiled pattern to
                     42: see if it was compiled with the opposite endianness. If so, it uses an
                     43: auxiliary 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
                     58: order to flip its bytes to see if we are dealing with a pattern that was
                     59: compiled on a host of different endianness. If so, this function is used to
                     60: flip other byte values.
                     61: 
                     62: Arguments:
                     63:   value        the number to flip
                     64:   n            the number of bytes to flip (assumed to be 2 or 4)
                     65: 
                     66: Returns:       the flipped value
                     67: */
                     68: 
                     69: static unsigned long int
                     70: byteflip(unsigned long int value, int n)
                     71: {
                     72: if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);
                     73: return ((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
                     86: pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that
                     87: is, it was compiled on a system of opposite endianness. The function is called
                     88: only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped,
                     89: we flip all the relevant values into a different data block, and return it.
                     90: 
                     91: Arguments:
                     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: 
                     97: Returns:           the new block if is is indeed a byte-flipped regex
                     98:                    NULL if it is not
                     99: */
                    100: 
                    101: real_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: {
                    105: if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
                    106:   return NULL;
                    107: 
                    108: *internal_re = *re;           /* To copy other fields */
                    109: internal_re->size = byteflip(re->size, sizeof(re->size));
                    110: internal_re->options = byteflip(re->options, sizeof(re->options));
                    111: internal_re->flags = (pcre_uint16)byteflip(re->flags, sizeof(re->flags));
                    112: internal_re->top_bracket =
                    113:   (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket));
                    114: internal_re->top_backref =
                    115:   (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref));
                    116: internal_re->first_byte =
                    117:   (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte));
                    118: internal_re->req_byte =
                    119:   (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte));
                    120: internal_re->name_table_offset =
                    121:   (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset));
                    122: internal_re->name_entry_size =
                    123:   (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size));
                    124: internal_re->name_count =
                    125:   (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count));
                    126: 
                    127: if (study != NULL)
                    128:   {
                    129:   *internal_study = *study;   /* To copy other fields */
                    130:   internal_study->size = byteflip(study->size, sizeof(study->size));
                    131:   internal_study->flags = byteflip(study->flags, sizeof(study->flags));
                    132:   internal_study->minlength = byteflip(study->minlength,
                    133:     sizeof(study->minlength));
                    134:   }
                    135: 
                    136: return internal_re;
                    137: }
                    138: 
                    139: /* End of pcre_tryflipped.c */