1 | /************************************************* |
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2 | * Perl-Compatible Regular Expressions * |
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3 | *************************************************/ |
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4 | |
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5 | /* PCRE is a library of functions to support regular expressions whose syntax |
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6 | and semantics are as close as possible to those of the Perl 5 language. |
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7 | |
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8 | Written by Philip Hazel |
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9 | Copyright (c) 1997-2008 University of Cambridge |
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10 | |
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11 | ----------------------------------------------------------------------------- |
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12 | Redistribution and use in source and binary forms, with or without |
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13 | modification, are permitted provided that the following conditions are met: |
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14 | |
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15 | * Redistributions of source code must retain the above copyright notice, |
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16 | this list of conditions and the following disclaimer. |
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17 | |
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18 | * Redistributions in binary form must reproduce the above copyright |
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19 | notice, this list of conditions and the following disclaimer in the |
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20 | documentation and/or other materials provided with the distribution. |
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21 | |
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22 | * Neither the name of the University of Cambridge nor the names of its |
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23 | contributors may be used to endorse or promote products derived from |
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24 | this software without specific prior written permission. |
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25 | |
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26 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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27 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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28 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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29 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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30 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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31 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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32 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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33 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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34 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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35 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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36 | POSSIBILITY OF SUCH DAMAGE. |
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37 | ----------------------------------------------------------------------------- |
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38 | */ |
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39 | |
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40 | |
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41 | /* This module contains an internal function that tests a compiled pattern to |
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42 | see if it was compiled with the opposite endianness. If so, it uses an |
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43 | auxiliary local function to flip the appropriate bytes. */ |
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44 | |
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45 | |
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46 | #include "pcre_config.h" |
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47 | #include "pcre_internal.h" |
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48 | |
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49 | |
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50 | /************************************************* |
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51 | * Flip bytes in an integer * |
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52 | *************************************************/ |
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53 | |
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54 | /* This function is called when the magic number in a regex doesn't match, in |
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55 | order to flip its bytes to see if we are dealing with a pattern that was |
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56 | compiled on a host of different endianness. If so, this function is used to |
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57 | flip other byte values. |
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58 | |
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59 | Arguments: |
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60 | value the number to flip |
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61 | n the number of bytes to flip (assumed to be 2 or 4) |
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62 | |
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63 | Returns: the flipped value |
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64 | */ |
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65 | |
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66 | static unsigned long int |
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67 | byteflip(unsigned long int value, int n) |
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68 | { |
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69 | if (n == 2) return ((value & 0x00ff) << 8) | ((value & 0xff00) >> 8); |
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70 | return ((value & 0x000000ff) << 24) | |
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71 | ((value & 0x0000ff00) << 8) | |
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72 | ((value & 0x00ff0000) >> 8) | |
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73 | ((value & 0xff000000) >> 24); |
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74 | } |
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75 | |
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76 | |
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77 | |
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78 | /************************************************* |
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79 | * Test for a byte-flipped compiled regex * |
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80 | *************************************************/ |
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81 | |
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82 | /* This function is called from pcre_exec(), pcre_dfa_exec(), and also from |
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83 | pcre_fullinfo(). Its job is to test whether the regex is byte-flipped - that |
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84 | is, it was compiled on a system of opposite endianness. The function is called |
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85 | only when the native MAGIC_NUMBER test fails. If the regex is indeed flipped, |
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86 | we flip all the relevant values into a different data block, and return it. |
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87 | |
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88 | Arguments: |
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89 | re points to the regex |
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90 | study points to study data, or NULL |
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91 | internal_re points to a new regex block |
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92 | internal_study points to a new study block |
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93 | |
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94 | Returns: the new block if is is indeed a byte-flipped regex |
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95 | NULL if it is not |
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96 | */ |
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97 | |
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98 | real_pcre * |
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99 | _pcre_try_flipped(const real_pcre *re, real_pcre *internal_re, |
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100 | const pcre_study_data *study, pcre_study_data *internal_study) |
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101 | { |
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102 | if (byteflip(re->magic_number, sizeof(re->magic_number)) != MAGIC_NUMBER) |
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103 | return NULL; |
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104 | |
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105 | *internal_re = *re; /* To copy other fields */ |
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106 | internal_re->size = byteflip(re->size, sizeof(re->size)); |
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107 | internal_re->options = byteflip(re->options, sizeof(re->options)); |
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108 | internal_re->flags = (pcre_uint16)byteflip(re->flags, sizeof(re->flags)); |
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109 | internal_re->top_bracket = |
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110 | (pcre_uint16)byteflip(re->top_bracket, sizeof(re->top_bracket)); |
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111 | internal_re->top_backref = |
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112 | (pcre_uint16)byteflip(re->top_backref, sizeof(re->top_backref)); |
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113 | internal_re->first_byte = |
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114 | (pcre_uint16)byteflip(re->first_byte, sizeof(re->first_byte)); |
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115 | internal_re->req_byte = |
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116 | (pcre_uint16)byteflip(re->req_byte, sizeof(re->req_byte)); |
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117 | internal_re->name_table_offset = |
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118 | (pcre_uint16)byteflip(re->name_table_offset, sizeof(re->name_table_offset)); |
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119 | internal_re->name_entry_size = |
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120 | (pcre_uint16)byteflip(re->name_entry_size, sizeof(re->name_entry_size)); |
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121 | internal_re->name_count = |
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122 | (pcre_uint16)byteflip(re->name_count, sizeof(re->name_count)); |
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123 | |
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124 | if (study != NULL) |
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125 | { |
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126 | *internal_study = *study; /* To copy other fields */ |
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127 | internal_study->size = byteflip(study->size, sizeof(study->size)); |
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128 | internal_study->options = byteflip(study->options, sizeof(study->options)); |
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129 | } |
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130 | |
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131 | return internal_re; |
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132 | } |
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133 | |
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134 | /* End of pcre_tryflipped.c */ |
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