Ulrich Drepper | b08d5a8 | 2005-07-26 05:00:05 +0000 | [diff] [blame^] | 1 | /* Get offset of next compilation unit. |
| 2 | Copyright (C) 2000, 2002 Red Hat, Inc. |
| 3 | Written by Ulrich Drepper <drepper@redhat.com>, 2000. |
| 4 | |
| 5 | This program is Open Source software; you can redistribute it and/or |
| 6 | modify it under the terms of the Open Software License version 1.0 as |
| 7 | published by the Open Source Initiative. |
| 8 | |
| 9 | You should have received a copy of the Open Software License along |
| 10 | with this program; if not, you may obtain a copy of the Open Software |
| 11 | License version 1.0 from http://www.opensource.org/licenses/osl.php or |
| 12 | by writing the Open Source Initiative c/o Lawrence Rosen, Esq., |
| 13 | 3001 King Ranch Road, Ukiah, CA 95482. */ |
| 14 | |
| 15 | #ifdef HAVE_CONFIG_H |
| 16 | # include <config.h> |
| 17 | #endif |
| 18 | |
| 19 | #include <assert.h> |
| 20 | #include <stdlib.h> |
| 21 | |
| 22 | #include <libdwarfP.h> |
| 23 | |
| 24 | |
| 25 | /* A good initial size for the abbreviation hashing table. */ |
| 26 | #define DEFAULT_ABBREV_HASH_SIZE 257 |
| 27 | |
| 28 | |
| 29 | int |
| 30 | internal_function |
| 31 | __libdwarf_get_cu_at_offset (Dwarf_Debug dbg, Dwarf_Unsigned offset, |
| 32 | Dwarf_CU_Info *result_cu, Dwarf_Error *error) |
| 33 | { |
| 34 | Dwarf_CU_Info cu; |
| 35 | Dwarf_Small *cu_bytes; |
| 36 | Dwarf_Unsigned length; |
| 37 | Dwarf_Half offset_size; |
| 38 | |
| 39 | /* Make sure there is enough space in the .debug_info section for at |
| 40 | least the initial word. We cannot test the rest since we don't |
| 41 | know yet whether this is a 64-bit object or not. */ |
| 42 | if (unlikely (offset + 4 >= dbg->sections[IDX_debug_info].size)) |
| 43 | { |
| 44 | dbg->cu_list_current = NULL; |
| 45 | return DW_DLV_NO_ENTRY; |
| 46 | } |
| 47 | |
| 48 | /* This points into the .debug_info section to the beginning of the |
| 49 | CU entry. */ |
| 50 | cu_bytes = (Dwarf_Small *) dbg->sections[IDX_debug_info].addr + offset; |
| 51 | |
| 52 | /* The format of the CU header is described in dwarf2p1 7.5.1: |
| 53 | |
| 54 | 1. A 4-byte or 12-byte unsigned integer representing the length |
| 55 | of the .debug_info contribution for that compilation unit, not |
| 56 | including the length field itself. In the 32-bit DWARF format, |
| 57 | this is a 4-byte unsigned integer (which must be less than |
| 58 | 0xffffff00); in the 64-bit DWARF format, this consists of the |
| 59 | 4-byte value 0xffffffff followed by an 8-byte unsigned integer |
| 60 | that gives the actual length (see Section 7.4). |
| 61 | |
| 62 | 2. A 2-byte unsigned integer representing the version of the |
| 63 | DWARF information for that compilation unit. For DWARF Version |
| 64 | 2.1, the value in this field is 2. |
| 65 | |
| 66 | 3. A 4-byte or 8-byte unsigned offset into the .debug_abbrev |
| 67 | section. This offset associates the compilation unit with a |
| 68 | particular set of debugging information entry abbreviations. In |
| 69 | the 32-bit DWARF format, this is a 4-byte unsigned length; in |
| 70 | the 64-bit DWARF format, this is an 8-byte unsigned length (see |
| 71 | Section 7.4). |
| 72 | |
| 73 | 4. A 1-byte unsigned integer representing the size in bytes of |
| 74 | an address on the target architecture. If the system uses |
| 75 | segmented addressing, this value represents the size of the |
| 76 | offset portion of an address. */ |
| 77 | length = read_4ubyte_unaligned (dbg, cu_bytes); |
| 78 | cu_bytes += 4; |
| 79 | offset_size = 4; |
| 80 | if (length == 0xffffffff) |
| 81 | offset_size = 8; |
| 82 | |
| 83 | /* Now we know how large the header is. Note the trick in the |
| 84 | computation. If the offset_size is 4 the '- 4' term undoes the |
| 85 | '2 *'. If offset_size is 8 this term computes the size of the |
| 86 | escape value plus the 8 byte offset. */ |
| 87 | if (unlikely (offset + 2 * offset_size - 4 + sizeof (Dwarf_Half) |
| 88 | + offset_size + sizeof (Dwarf_Small) |
| 89 | >= dbg->sections[IDX_debug_info].size)) |
| 90 | { |
| 91 | dbg->cu_list_current = NULL; |
| 92 | return DW_DLV_NO_ENTRY; |
| 93 | } |
| 94 | |
| 95 | if (length == 0xffffffff) |
| 96 | { |
| 97 | /* This is a 64-bit DWARF format. */ |
| 98 | length = read_8ubyte_unaligned (dbg, cu_bytes); |
| 99 | cu_bytes += 8; |
| 100 | } |
| 101 | |
| 102 | /* We know we have enough room in the .debug_section. Allocate the |
| 103 | result data structure. */ |
| 104 | cu = (Dwarf_CU_Info) malloc (sizeof (struct Dwarf_CU_Info_s)); |
| 105 | if (cu == NULL) |
| 106 | { |
| 107 | __libdwarf_error (dbg, error, DW_E_NOMEM); |
| 108 | return DW_DLV_ERROR; |
| 109 | } |
| 110 | |
| 111 | /* Store the values in the data structure. */ |
| 112 | cu->offset = offset; |
| 113 | cu->offset_size = offset_size; |
| 114 | cu->length = length; |
| 115 | |
| 116 | /* Store the version stamp. Always a 16-bit value. */ |
| 117 | cu->version_stamp = read_2ubyte_unaligned (dbg, cu_bytes); |
| 118 | cu_bytes += 2; |
| 119 | |
| 120 | /* Get offset in .debug_abbrev. Note that the size of the entry |
| 121 | depends on whether this is a 32-bit or 64-bit DWARF definition. */ |
| 122 | if (offset_size == 4) |
| 123 | cu->abbrev_offset = read_4ubyte_unaligned (dbg, cu_bytes); |
| 124 | else |
| 125 | cu->abbrev_offset = read_8ubyte_unaligned (dbg, cu_bytes); |
| 126 | cu_bytes += offset_size; |
| 127 | cu->last_abbrev_offset = cu->abbrev_offset; |
| 128 | |
| 129 | /* The address size. Always an 8-bit value. */ |
| 130 | cu->address_size = *cu_bytes++; |
| 131 | |
| 132 | /* Store the header length. */ |
| 133 | cu->header_length = (cu_bytes |
| 134 | - ((Dwarf_Small *) dbg->sections[IDX_debug_info].addr |
| 135 | + offset)); |
| 136 | |
| 137 | /* Initilize a few more members. */ |
| 138 | if (unlikely (Dwarf_Abbrev_Hash_init (&cu->abbrev_hash, |
| 139 | DEFAULT_ABBREV_HASH_SIZE) != 0)) |
| 140 | { |
| 141 | free (cu); |
| 142 | __libdwarf_error (dbg, error, DW_E_NOMEM); |
| 143 | return DW_DLV_ERROR; |
| 144 | } |
| 145 | |
| 146 | /* Remember the debugging handle. */ |
| 147 | cu->dbg = dbg; |
| 148 | |
| 149 | /* There is no other entry yet. */ |
| 150 | cu->next = NULL; |
| 151 | |
| 152 | /* Enqueue the new entry. */ |
| 153 | if (dbg->cu_list == NULL) |
| 154 | dbg->cu_list = dbg->cu_list_tail = cu; |
| 155 | else |
| 156 | { |
| 157 | dbg->cu_list_tail->next = cu; |
| 158 | dbg->cu_list_tail = cu; |
| 159 | } |
| 160 | *result_cu = cu; |
| 161 | |
| 162 | return DW_DLV_OK; |
| 163 | } |
| 164 | |
| 165 | |
| 166 | int |
| 167 | dwarf_next_cu_header (dbg, cu_header_length, version_stamp, abbrev_offset, |
| 168 | address_size, next_cu_header, error) |
| 169 | Dwarf_Debug dbg; |
| 170 | Dwarf_Unsigned *cu_header_length; |
| 171 | Dwarf_Half *version_stamp; |
| 172 | Dwarf_Unsigned *abbrev_offset; |
| 173 | Dwarf_Half *address_size; |
| 174 | Dwarf_Unsigned *next_cu_header; |
| 175 | Dwarf_Error *error; |
| 176 | { |
| 177 | Dwarf_Unsigned offset_next_cu; |
| 178 | Dwarf_CU_Info cu; |
| 179 | |
| 180 | if (dbg == NULL) |
| 181 | return DW_DLV_ERROR; |
| 182 | |
| 183 | /* Determine offset of next CU header. If we don't have a current |
| 184 | CU this is the first call and we start right at the beginning. */ |
| 185 | if (dbg->cu_list_current == NULL) |
| 186 | { |
| 187 | offset_next_cu = 0; |
| 188 | cu = dbg->cu_list; |
| 189 | } |
| 190 | else |
| 191 | { |
| 192 | /* We can compute the offset from the information we read from |
| 193 | the last CU header. */ |
| 194 | cu = dbg->cu_list_current; |
| 195 | |
| 196 | offset_next_cu = cu->offset + 2 * cu->offset_size - 4 + cu->length; |
| 197 | |
| 198 | /* See whether the next entry entry is available. */ |
| 199 | cu = cu->next; |
| 200 | } |
| 201 | |
| 202 | /* If the entry is not yet available get it. */ |
| 203 | if (cu == NULL) |
| 204 | { |
| 205 | int res = __libdwarf_get_cu_at_offset (dbg, offset_next_cu, &cu, error); |
| 206 | |
| 207 | /* If it still does not exist, fail. Note that this can mean an |
| 208 | error or that we reached the end. */ |
| 209 | if (res != DW_DLV_OK) |
| 210 | return res; |
| 211 | |
| 212 | dbg->cu_list_current = cu; |
| 213 | assert (cu != NULL); |
| 214 | } |
| 215 | |
| 216 | /* See get_cu_at_offset for an explanation of the trick in this |
| 217 | formula. */ |
| 218 | *next_cu_header = offset_next_cu + 2 * cu->offset_size - 4 + cu->length; |
| 219 | |
| 220 | /* Extract the information and put it where the user wants it. */ |
| 221 | if (cu_header_length != NULL) |
| 222 | *cu_header_length = cu->header_length; |
| 223 | |
| 224 | if (version_stamp != NULL) |
| 225 | *version_stamp = cu->version_stamp; |
| 226 | |
| 227 | if (abbrev_offset != NULL) |
| 228 | *abbrev_offset = cu->abbrev_offset; |
| 229 | |
| 230 | if (address_size != NULL) |
| 231 | *address_size = cu->address_size; |
| 232 | |
| 233 | return DW_DLV_OK; |
| 234 | } |