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92e772ff | 1 | /* $Cambridge: exim/src/src/pcre/pcre_try_flipped.c,v 1.2 2005/08/08 10:22:14 ph10 Exp $ */ |
8ac170f3 PH |
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 */ |