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root/svn/ircd-hybrid-7.2/lib/pcre/pcre_try_flipped.c
Revision: 34
Committed: Sun Oct 2 21:05:51 2005 UTC (18 years, 5 months ago) by lusky
Content type: text/x-csrc
File size: 5355 byte(s)
Log Message:
create 7.2 branch, we can move/rename it as needed.


File Contents

# Content
1 /* $Id$ */
2
3 /*************************************************
4 * Perl-Compatible Regular Expressions *
5 *************************************************/
6
7 /* PCRE is a library of functions to support regular expressions whose syntax
8 and semantics are as close as possible to those of the Perl 5 language.
9
10 Written by Philip Hazel
11 Copyright (c) 1997-2005 University of Cambridge
12
13 -----------------------------------------------------------------------------
14 Redistribution and use in source and binary forms, with or without
15 modification, are permitted provided that the following conditions are met:
16
17 * Redistributions of source code must retain the above copyright notice,
18 this list of conditions and the following disclaimer.
19
20 * Redistributions in binary form must reproduce the above copyright
21 notice, this list of conditions and the following disclaimer in the
22 documentation and/or other materials provided with the distribution.
23
24 * Neither the name of the University of Cambridge nor the names of its
25 contributors may be used to endorse or promote products derived from
26 this software without specific prior written permission.
27
28 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
29 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
32 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 POSSIBILITY OF SUCH DAMAGE.
39 -----------------------------------------------------------------------------
40 */
41
42
43 /* This module contains an internal function that tests a compiled pattern to
44 see if it was compiled with the opposite endianness. If so, it uses an
45 auxiliary local function to flip the appropriate bytes. */
46
47
48 #include "pcre_internal.h"
49
50
51 /*************************************************
52 * Flip bytes in an integer *
53 *************************************************/
54
55 /* This function is called when the magic number in a regex doesn't match, in
56 order to flip its bytes to see if we are dealing with a pattern that was
57 compiled on a host of different endianness. If so, this function is used to
58 flip other byte values.
59
60 Arguments:
61 value the number to flip
62 n the number of bytes to flip (assumed to be 2 or 4)
63
64 Returns: the flipped value
65 */
66
67 static long int
68 byteflip(long int value, int n)
69 {
70 if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);
71 return ((value & 0x000000ff) << 24) |
72 ((value & 0x0000ff00) << 8) |
73 ((value & 0x00ff0000) >> 8) |
74 ((value & 0xff000000) >> 24);
75 }
76
77
78
79 /*************************************************
80 * Test for a byte-flipped compiled regex *
81 *************************************************/
82
83 /* This function is called from pcre_exec(), pcre_dfa_exec(), and also from
84 pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that
85 is, it was compiled on a system of opposite endianness. The function is called
86 only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped,
87 we flip all the relevant values into a different data block, and return it.
88
89 Arguments:
90 re points to the regex
91 study points to study data, or NULL
92 internal_re points to a new regex block
93 internal_study points to a new study block
94
95 Returns: the new block if is is indeed a byte-flipped regex
96 NULL if it is not
97 */
98
99 EXPORT real_pcre *
100 _pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,
101 const pcre_study_data *study, pcre_study_data *internal_study)
102 {
103 if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
104 return NULL;
105
106 *internal_re = *re; /* To copy other fields */
107 internal_re->size = byteflip(re->size, sizeof(re->size));
108 internal_re->options = byteflip(re->options, sizeof(re->options));
109 internal_re->top_bracket =
110 (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket));
111 internal_re->top_backref =
112 (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref));
113 internal_re->first_byte =
114 (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte));
115 internal_re->req_byte =
116 (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte));
117 internal_re->name_table_offset =
118 (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset));
119 internal_re->name_entry_size =
120 (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size));
121 internal_re->name_count =
122 (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count));
123
124 if (study != NULL)
125 {
126 *internal_study = *study; /* To copy other fields */
127 internal_study->size = byteflip(study->size, sizeof(study->size));
128 internal_study->options = byteflip(study->options, sizeof(study->options));
129 }
130
131 return internal_re;
132 }
133
134 /* End of pcre_tryflipped.c */

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