Tristan Matthews | 0461646 | 2013-11-14 16:09:34 -0500 | [diff] [blame] | 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) 1997-2009 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->flags = byteflip(study->flags, sizeof(study->flags)); |
| 132 | internal_study->minlength = byteflip(study->minlength, |
| 133 | sizeof(study->minlength)); |
| 134 | } |
| 135 | |
| 136 | return internal_re; |
| 137 | } |
| 138 | |
| 139 | /* End of pcre_tryflipped.c */ |