1 /* Advance to next CU header. 2 Copyright (C) 2002-2010 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper (at) redhat.com>, 2002. 5 6 This file is free software; you can redistribute it and/or modify 7 it under the terms of either 8 9 * the GNU Lesser General Public License as published by the Free 10 Software Foundation; either version 3 of the License, or (at 11 your option) any later version 12 13 or 14 15 * the GNU General Public License as published by the Free 16 Software Foundation; either version 2 of the License, or (at 17 your option) any later version 18 19 or both in parallel, as here. 20 21 elfutils is distributed in the hope that it will be useful, but 22 WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 General Public License for more details. 25 26 You should have received copies of the GNU General Public License and 27 the GNU Lesser General Public License along with this program. If 28 not, see <http://www.gnu.org/licenses/>. */ 29 30 #ifdef HAVE_CONFIG_H 31 # include <config.h> 32 #endif 33 34 #include <libdwP.h> 35 #include <dwarf.h> 36 37 38 int 39 dwarf_next_unit (dwarf, off, next_off, header_sizep, versionp, abbrev_offsetp, 40 address_sizep, offset_sizep, type_signaturep, type_offsetp) 41 Dwarf *dwarf; 42 Dwarf_Off off; 43 Dwarf_Off *next_off; 44 size_t *header_sizep; 45 Dwarf_Half *versionp; 46 Dwarf_Off *abbrev_offsetp; 47 uint8_t *address_sizep; 48 uint8_t *offset_sizep; 49 uint64_t *type_signaturep; 50 Dwarf_Off *type_offsetp; 51 { 52 const bool debug_types = type_signaturep != NULL; 53 const size_t sec_idx = debug_types ? IDX_debug_types : IDX_debug_info; 54 55 /* Maybe there has been an error before. */ 56 if (dwarf == NULL) 57 return -1; 58 59 /* If we reached the end before don't do anything. */ 60 if (off == (Dwarf_Off) -1l 61 || unlikely (dwarf->sectiondata[sec_idx] == NULL) 62 /* Make sure there is enough space in the .debug_info section 63 for at least the initial word. We cannot test the rest since 64 we don't know yet whether this is a 64-bit object or not. */ 65 || unlikely (off + 4 >= dwarf->sectiondata[sec_idx]->d_size)) 66 { 67 *next_off = (Dwarf_Off) -1l; 68 return 1; 69 } 70 71 /* This points into the .debug_info section to the beginning of the 72 CU entry. */ 73 const unsigned char *data = dwarf->sectiondata[sec_idx]->d_buf; 74 const unsigned char *bytes = data + off; 75 76 /* The format of the CU header is described in dwarf2p1 7.5.1: 77 78 1. A 4-byte or 12-byte unsigned integer representing the length 79 of the .debug_info contribution for that compilation unit, not 80 including the length field itself. In the 32-bit DWARF format, 81 this is a 4-byte unsigned integer (which must be less than 82 0xfffffff0); in the 64-bit DWARF format, this consists of the 83 4-byte value 0xffffffff followed by an 8-byte unsigned integer 84 that gives the actual length (see Section 7.2.2). 85 86 2. A 2-byte unsigned integer representing the version of the 87 DWARF information for that compilation unit. For DWARF Version 88 2.1, the value in this field is 2. 89 90 3. A 4-byte or 8-byte unsigned offset into the .debug_abbrev 91 section. This offset associates the compilation unit with a 92 particular set of debugging information entry abbreviations. In 93 the 32-bit DWARF format, this is a 4-byte unsigned length; in 94 the 64-bit DWARF format, this is an 8-byte unsigned length (see 95 Section 7.4). 96 97 4. A 1-byte unsigned integer representing the size in bytes of 98 an address on the target architecture. If the system uses 99 segmented addressing, this value represents the size of the 100 offset portion of an address. */ 101 uint64_t length = read_4ubyte_unaligned_inc (dwarf, bytes); 102 size_t offset_size = 4; 103 /* Lengths of 0xfffffff0 - 0xffffffff are escape codes. Oxffffffff is 104 used to indicate that 64-bit dwarf information is being used, the 105 other values are currently reserved. */ 106 if (length == DWARF3_LENGTH_64_BIT) 107 offset_size = 8; 108 else if (unlikely (length >= DWARF3_LENGTH_MIN_ESCAPE_CODE 109 && length <= DWARF3_LENGTH_MAX_ESCAPE_CODE)) 110 { 111 invalid: 112 __libdw_seterrno (DWARF_E_INVALID_DWARF); 113 return -1; 114 } 115 116 /* Now we know how large the header is. */ 117 if (unlikely (DIE_OFFSET_FROM_CU_OFFSET (off, offset_size, debug_types) 118 >= dwarf->sectiondata[sec_idx]->d_size)) 119 { 120 *next_off = -1; 121 return 1; 122 } 123 124 if (length == DWARF3_LENGTH_64_BIT) 125 /* This is a 64-bit DWARF format. */ 126 length = read_8ubyte_unaligned_inc (dwarf, bytes); 127 128 /* Read the version stamp. Always a 16-bit value. */ 129 uint_fast16_t version = read_2ubyte_unaligned_inc (dwarf, bytes); 130 131 /* Get offset in .debug_abbrev. Note that the size of the entry 132 depends on whether this is a 32-bit or 64-bit DWARF definition. */ 133 uint64_t abbrev_offset; 134 if (__libdw_read_offset_inc (dwarf, sec_idx, &bytes, offset_size, 135 &abbrev_offset, IDX_debug_abbrev, 0)) 136 return -1; 137 138 /* The address size. Always an 8-bit value. */ 139 uint8_t address_size = *bytes++; 140 141 if (debug_types) 142 { 143 uint64_t type_sig8 = read_8ubyte_unaligned_inc (dwarf, bytes); 144 145 Dwarf_Off type_offset; 146 if (__libdw_read_offset_inc (dwarf, sec_idx, &bytes, offset_size, 147 &type_offset, sec_idx, 0)) 148 return -1; 149 150 /* Validate that the TYPE_OFFSET points past the header. */ 151 if (unlikely (type_offset < (size_t) (bytes - (data + off)))) 152 goto invalid; 153 154 *type_signaturep = type_sig8; 155 if (type_offsetp != NULL) 156 *type_offsetp = type_offset; 157 } 158 159 /* Store the header length. */ 160 if (header_sizep != NULL) 161 *header_sizep = bytes - (data + off); 162 163 if (versionp != NULL) 164 *versionp = version; 165 166 if (abbrev_offsetp != NULL) 167 *abbrev_offsetp = abbrev_offset; 168 169 if (address_sizep != NULL) 170 *address_sizep = address_size; 171 172 /* Store the offset size. */ 173 if (offset_sizep != NULL) 174 *offset_sizep = offset_size; 175 176 /* See definition of DIE_OFFSET_FROM_CU_OFFSET macro 177 for an explanation of the trick in this expression. */ 178 *next_off = off + 2 * offset_size - 4 + length; 179 180 return 0; 181 } 182 INTDEF(dwarf_next_unit) 183 184 int 185 dwarf_nextcu (dwarf, off, next_off, header_sizep, abbrev_offsetp, 186 address_sizep, offset_sizep) 187 Dwarf *dwarf; 188 Dwarf_Off off; 189 Dwarf_Off *next_off; 190 size_t *header_sizep; 191 Dwarf_Off *abbrev_offsetp; 192 uint8_t *address_sizep; 193 uint8_t *offset_sizep; 194 { 195 return INTUSE(dwarf_next_unit) (dwarf, off, next_off, header_sizep, NULL, 196 abbrev_offsetp, address_sizep, offset_sizep, 197 NULL, NULL); 198 } 199 INTDEF(dwarf_nextcu) 200
