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) 1997-2006 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 : #include "pcre_internal.h"
47 :
48 :
49 : /*************************************************
50 : * Flip bytes in an integer *
51 : *************************************************/
52 :
53 : /* This function is called when the magic number in a regex doesn't match, in
54 : order to flip its bytes to see if we are dealing with a pattern that was
55 : compiled on a host of different endianness. If so, this function is used to
56 : flip other byte values.
57 :
58 : Arguments:
59 : value the number to flip
60 : n the number of bytes to flip (assumed to be 2 or 4)
61 :
62 : Returns: the flipped value
63 : */
64 :
65 : static unsigned long int
66 : byteflip(unsigned long int value, int n)
67 0 : {
68 0 : if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);
69 0 : return ((value & 0x000000ff) << 24) |
70 : ((value & 0x0000ff00) << 8) |
71 : ((value & 0x00ff0000) >> 8) |
72 : ((value & 0xff000000) >> 24);
73 : }
74 :
75 :
76 :
77 : /*************************************************
78 : * Test for a byte-flipped compiled regex *
79 : *************************************************/
80 :
81 : /* This function is called from pcre_exec(), pcre_dfa_exec(), and also from
82 : pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that
83 : is, it was compiled on a system of opposite endianness. The function is called
84 : only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped,
85 : we flip all the relevant values into a different data block, and return it.
86 :
87 : Arguments:
88 : re points to the regex
89 : study points to study data, or NULL
90 : internal_re points to a new regex block
91 : internal_study points to a new study block
92 :
93 : Returns: the new block if is is indeed a byte-flipped regex
94 : NULL if it is not
95 : */
96 :
97 : real_pcre *
98 : _pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,
99 : const pcre_study_data *study, pcre_study_data *internal_study)
100 0 : {
101 0 : if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
102 0 : return NULL;
103 :
104 0 : *internal_re = *re; /* To copy other fields */
105 0 : internal_re->size = byteflip(re->size, sizeof(re->size));
106 0 : internal_re->options = byteflip(re->options, sizeof(re->options));
107 0 : internal_re->top_bracket =
108 : (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket));
109 0 : internal_re->top_backref =
110 : (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref));
111 0 : internal_re->first_byte =
112 : (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte));
113 0 : internal_re->req_byte =
114 : (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte));
115 0 : internal_re->name_table_offset =
116 : (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset));
117 0 : internal_re->name_entry_size =
118 : (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size));
119 0 : internal_re->name_count =
120 : (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count));
121 :
122 0 : if (study != NULL)
123 : {
124 0 : *internal_study = *study; /* To copy other fields */
125 0 : internal_study->size = byteflip(study->size, sizeof(study->size));
126 0 : internal_study->options = byteflip(study->options, sizeof(study->options));
127 : }
128 :
129 0 : return internal_re;
130 : }
131 :
132 : /* End of pcre_tryflipped.c */
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