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NCBI C++ Toolkit Cross ReferenceC++/src/util/regexp/pcre_try_flipped.c |
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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) 1997-2008 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->options = byteflip(study->options, sizeof(study->options));
132 }
133
134 return internal_re;
135 }
136
137 /* End of pcre_tryflipped.c */
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