1 /* 2 Copyright (C) 2000,2004 Silicon Graphics, Inc. All Rights Reserved. 3 Portions Copyright 2011-2018 David Anderson. All Rights Reserved. 4 5 This program is free software; you can redistribute it and/or modify it 6 under the terms of version 2.1 of the GNU Lesser General Public License 7 as published by the Free Software Foundation. 8 9 This program is distributed in the hope that it would be useful, but 10 WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 12 13 Further, this software is distributed without any warranty that it is 14 free of the rightful claim of any third person regarding infringement 15 or the like. Any license provided herein, whether implied or 16 otherwise, applies only to this software file. Patent licenses, if 17 any, provided herein do not apply to combinations of this program with 18 other software, or any other product whatsoever. 19 20 You should have received a copy of the GNU Lesser General Public 21 License along with this program; if not, write the Free Software 22 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301, 23 USA. 24 25 */ 26 27 28 #include "config.h" 29 #include <stdio.h> 30 #include "dwarf_incl.h" 31 #include "dwarf_error.h" 32 #include "dwarf_util.h" 33 34 /* Note that with 'make check') 35 many of the test items 36 only make sense if Dwarf_Unsigned (and Dwarf_Signed) 37 are 64 bits. The encode/decode logic should 38 be fine whether those types are 64 or 32 bits. 39 See runtests.sh */ 40 41 /* 10 bytes of leb, 7 bits each part of the number, gives 42 room for a 64bit number. 43 While any number of leading zeroes would be legal, so 44 no max is really truly required here, why would a 45 compiler generate leading zeros? That would 46 be strange. 47 */ 48 #define BYTESLEBMAX 10 49 #define BITSPERBYTE 8 50 51 52 /* Decode ULEB with checking */ 53 int 54 _dwarf_decode_u_leb128_chk(Dwarf_Small * leb128, 55 Dwarf_Unsigned * leb128_length, 56 Dwarf_Unsigned *outval, 57 Dwarf_Byte_Ptr endptr) 58 { 59 Dwarf_Unsigned byte = 0; 60 Dwarf_Unsigned word_number = 0; 61 Dwarf_Unsigned number = 0; 62 unsigned shift = 0; 63 /* The byte_length value will be a small non-negative integer. */ 64 unsigned byte_length = 0; 65 66 if (leb128 >=endptr) { 67 return DW_DLV_ERROR; 68 } 69 /* The following unrolls-the-loop for the first two bytes and 70 unpacks into 32 bits to make this as fast as possible. 71 word_number is assumed big enough that the shift has a defined 72 result. */ 73 if ((*leb128 & 0x80) == 0) { 74 if (leb128_length) { 75 *leb128_length = 1; 76 } 77 *outval = *leb128; 78 return DW_DLV_OK; 79 } else { 80 if ((leb128+1) >=endptr) { 81 return DW_DLV_ERROR; 82 } 83 if ((*(leb128 + 1) & 0x80) == 0) { 84 if (leb128_length) { 85 *leb128_length = 2; 86 } 87 word_number = *leb128 & 0x7f; 88 word_number |= (*(leb128 + 1) & 0x7f) << 7; 89 *outval = word_number; 90 return DW_DLV_OK; 91 } 92 /* Gets messy to hand-inline more byte checking. */ 93 } 94 95 /* The rest handles long numbers Because the 'number' may be larger 96 than the default int/unsigned, we must cast the 'byte' before 97 the shift for the shift to have a defined result. */ 98 number = 0; 99 shift = 0; 100 byte_length = 1; 101 byte = *leb128; 102 for (;;) { 103 if (shift >= (sizeof(number)*BITSPERBYTE)) { 104 return DW_DLV_ERROR; 105 } 106 number |= (byte & 0x7f) << shift; 107 if ((byte & 0x80) == 0) { 108 if (leb128_length) { 109 *leb128_length = byte_length; 110 } 111 *outval = number; 112 return DW_DLV_OK; 113 } 114 shift += 7; 115 byte_length++; 116 if (byte_length > BYTESLEBMAX) { 117 /* Erroneous input. */ 118 if( leb128_length) { 119 *leb128_length = BYTESLEBMAX; 120 } 121 break; 122 } 123 ++leb128; 124 if ((leb128) >=endptr) { 125 return DW_DLV_ERROR; 126 } 127 byte = *leb128; 128 } 129 return DW_DLV_ERROR; 130 } 131 132 133 #define BITSINBYTE 8 134 135 int 136 _dwarf_decode_s_leb128_chk(Dwarf_Small * leb128, Dwarf_Unsigned * leb128_length, 137 Dwarf_Signed *outval,Dwarf_Byte_Ptr endptr) 138 { 139 Dwarf_Unsigned byte = 0; 140 Dwarf_Signed number = 0; 141 Dwarf_Bool sign = 0; 142 Dwarf_Unsigned shift = 0; 143 /* The byte_length value will be a small non-negative integer. */ 144 unsigned byte_length = 1; 145 146 /* byte_length being the number of bytes of data absorbed so far in 147 turning the leb into a Dwarf_Signed. */ 148 if (!outval) { 149 return DW_DLV_ERROR; 150 } 151 if (leb128 >= endptr) { 152 return DW_DLV_ERROR; 153 } 154 byte = *leb128; 155 for (;;) { 156 sign = byte & 0x40; 157 if (shift >= (sizeof(number)*BITSPERBYTE)) { 158 return DW_DLV_ERROR; 159 } 160 number |= ((Dwarf_Unsigned) ((byte & 0x7f))) << shift; 161 shift += 7; 162 163 if ((byte & 0x80) == 0) { 164 break; 165 } 166 ++leb128; 167 if (leb128 >= endptr) { 168 return DW_DLV_ERROR; 169 } 170 byte = *leb128; 171 byte_length++; 172 if (byte_length > BYTESLEBMAX) { 173 /* Erroneous input. */ 174 if (leb128_length) { 175 *leb128_length = BYTESLEBMAX; 176 } 177 return DW_DLV_ERROR; 178 } 179 } 180 181 if (sign) { 182 /* The following avoids undefined behavior. */ 183 unsigned shiftlim = sizeof(Dwarf_Signed) * BITSINBYTE -1; 184 if (shift < shiftlim) { 185 number |= -(Dwarf_Signed)(((Dwarf_Unsigned)1) << shift); 186 } else if (shift == shiftlim) { 187 number |= (((Dwarf_Unsigned)1) << shift); 188 } 189 } 190 191 if (leb128_length) { 192 *leb128_length = byte_length; 193 } 194 *outval = number; 195 return DW_DLV_OK; 196 } 197