1 /*************************************************
2 * Perl-Compatible Regular Expressions *
3 *************************************************/
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.
8 Written by Philip Hazel
9 Copyright (c) 1997-2008 University of Cambridge
11 -----------------------------------------------------------------------------
12 Redistribution and use in source and binary forms, with or without
13 modification, are permitted provided that the following conditions are met:
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16 this list of conditions and the following disclaimer.
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19 notice, this list of conditions and the following disclaimer in the
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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.
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
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37 -----------------------------------------------------------------------------
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. */
50 #include "pcre_internal.h"
53 /*************************************************
54 * Flip bytes in an integer *
55 *************************************************/
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.
63 value the number to flip
64 n the number of bytes to flip (assumed to be 2 or 4)
66 Returns: the flipped value
69 static unsigned long int
70 byteflip(unsigned long int value, int n)
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);
81 /*************************************************
82 * Test for a byte-flipped compiled regex *
83 *************************************************/
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.
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
97 Returns: the new block if is is indeed a byte-flipped regex
102 _pcre_try_flipped(const real_pcre *re, real_pcre *internal_re,
103 const pcre_study_data *study, pcre_study_data *internal_study)
105 if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER)
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));
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));
137 /* End of pcre_tryflipped.c */
