/[pcre]/code/trunk/pcre_try_flipped.c
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Contents of /code/trunk/pcre_try_flipped.c

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Revision 91 - (hide annotations) (download)
Sat Feb 24 21:41:34 2007 UTC (7 years, 9 months ago) by nigel
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Load pcre-6.7 into code/trunk.

1 nigel 77 /*************************************************
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 nigel 87 Copyright (c) 1997-2006 University of Cambridge
10 nigel 77
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 nigel 91 static unsigned long int
66     byteflip(unsigned long int value, int n)
67 nigel 77 {
68     if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8);
69     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 nigel 87 real_pcre *
98 nigel 77 _pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,
99     const pcre_study_data *study, pcre_study_data *internal_study)
100     {
101     if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
102     return NULL;
103    
104     *internal_re = *re; /* To copy other fields */
105     internal_re->size = byteflip(re->size, sizeof(re->size));
106     internal_re->options = byteflip(re->options, sizeof(re->options));
107     internal_re->top_bracket =
108     (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket));
109     internal_re->top_backref =
110     (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref));
111     internal_re->first_byte =
112     (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte));
113     internal_re->req_byte =
114     (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte));
115     internal_re->name_table_offset =
116     (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset));
117     internal_re->name_entry_size =
118     (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size));
119     internal_re->name_count =
120     (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count));
121    
122     if (study != NULL)
123     {
124     *internal_study = *study; /* To copy other fields */
125     internal_study->size = byteflip(study->size, sizeof(study->size));
126     internal_study->options = byteflip(study->options, sizeof(study->options));
127     }
128    
129     return internal_re;
130     }
131    
132     /* End of pcre_tryflipped.c */

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