1 /* Get abbreviation at given offset. 2 Copyright (C) 2003, 2004, 2005, 2006, 2014 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper (at) redhat.com>, 2003. 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 <dwarf.h> 35 #include "libdwP.h" 36 37 38 Dwarf_Abbrev * 39 internal_function 40 __libdw_getabbrev (Dwarf *dbg, struct Dwarf_CU *cu, Dwarf_Off offset, 41 size_t *lengthp, Dwarf_Abbrev *result) 42 { 43 /* Don't fail if there is not .debug_abbrev section. */ 44 if (dbg->sectiondata[IDX_debug_abbrev] == NULL) 45 return NULL; 46 47 if (offset >= dbg->sectiondata[IDX_debug_abbrev]->d_size) 48 { 49 __libdw_seterrno (DWARF_E_INVALID_OFFSET); 50 return NULL; 51 } 52 53 const unsigned char *abbrevp 54 = (unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf + offset; 55 56 if (*abbrevp == '\0') 57 /* We are past the last entry. */ 58 return DWARF_END_ABBREV; 59 60 /* 7.5.3 Abbreviations Tables 61 62 [...] Each declaration begins with an unsigned LEB128 number 63 representing the abbreviation code itself. [...] The 64 abbreviation code is followed by another unsigned LEB128 65 number that encodes the entry's tag. [...] 66 67 [...] Following the tag encoding is a 1-byte value that 68 determines whether a debugging information entry using this 69 abbreviation has child entries or not. [...] 70 71 [...] Finally, the child encoding is followed by a series of 72 attribute specifications. Each attribute specification 73 consists of two parts. The first part is an unsigned LEB128 74 number representing the attribute's name. The second part is 75 an unsigned LEB128 number representing the attribute's form. */ 76 const unsigned char *end = (dbg->sectiondata[IDX_debug_abbrev]->d_buf 77 + dbg->sectiondata[IDX_debug_abbrev]->d_size); 78 const unsigned char *start_abbrevp = abbrevp; 79 unsigned int code; 80 get_uleb128 (code, abbrevp, end); 81 82 /* Check whether this code is already in the hash table. */ 83 bool foundit = false; 84 Dwarf_Abbrev *abb = NULL; 85 if (cu == NULL 86 || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code, NULL)) == NULL) 87 { 88 if (result == NULL) 89 abb = libdw_typed_alloc (dbg, Dwarf_Abbrev); 90 else 91 abb = result; 92 } 93 else 94 { 95 foundit = true; 96 97 if (unlikely (abb->offset != offset)) 98 { 99 /* A duplicate abbrev code at a different offset, 100 that should never happen. */ 101 invalid: 102 __libdw_seterrno (DWARF_E_INVALID_DWARF); 103 return NULL; 104 } 105 106 /* If the caller doesn't need the length we are done. */ 107 if (lengthp == NULL) 108 goto out; 109 } 110 111 /* If there is already a value in the hash table we are going to 112 overwrite its content. This must not be a problem, since the 113 content better be the same. */ 114 abb->code = code; 115 if (abbrevp >= end) 116 goto invalid; 117 get_uleb128 (abb->tag, abbrevp, end); 118 if (abbrevp + 1 >= end) 119 goto invalid; 120 abb->has_children = *abbrevp++ == DW_CHILDREN_yes; 121 abb->attrp = (unsigned char *) abbrevp; 122 abb->offset = offset; 123 124 /* Skip over all the attributes and count them while doing so. */ 125 abb->attrcnt = 0; 126 unsigned int attrname; 127 unsigned int attrform; 128 do 129 { 130 if (abbrevp >= end) 131 goto invalid; 132 get_uleb128 (attrname, abbrevp, end); 133 if (abbrevp >= end) 134 goto invalid; 135 get_uleb128 (attrform, abbrevp, end); 136 } 137 while (attrname != 0 && attrform != 0 && ++abb->attrcnt); 138 139 /* Return the length to the caller if she asked for it. */ 140 if (lengthp != NULL) 141 *lengthp = abbrevp - start_abbrevp; 142 143 /* Add the entry to the hash table. */ 144 if (cu != NULL && ! foundit) 145 (void) Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb); 146 147 out: 148 return abb; 149 } 150 151 152 Dwarf_Abbrev * 153 dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp) 154 { 155 return __libdw_getabbrev (die->cu->dbg, die->cu, 156 die->cu->orig_abbrev_offset + offset, lengthp, 157 NULL); 158 } 159
