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 */ 140
