1 /* Look up the DIE in a reference-form attribute. 2 Copyright (C) 2005-2010, 2018 Red Hat, Inc. 3 This file is part of elfutils. 4 5 This file is free software; you can redistribute it and/or modify 6 it under the terms of either 7 8 * the GNU Lesser General Public License as published by the Free 9 Software Foundation; either version 3 of the License, or (at 10 your option) any later version 11 12 or 13 14 * the GNU General Public License as published by the Free 15 Software Foundation; either version 2 of the License, or (at 16 your option) any later version 17 18 or both in parallel, as here. 19 20 elfutils is distributed in the hope that it will be useful, but 21 WITHOUT ANY WARRANTY; without even the implied warranty of 22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 23 General Public License for more details. 24 25 You should have received copies of the GNU General Public License and 26 the GNU Lesser General Public License along with this program. If 27 not, see <http://www.gnu.org/licenses/>. */ 28 29 #ifdef HAVE_CONFIG_H 30 # include <config.h> 31 #endif 32 33 #include <string.h> 34 #include "libdwP.h" 35 #include <dwarf.h> 36 37 38 Dwarf_Die * 39 dwarf_formref_die (Dwarf_Attribute *attr, Dwarf_Die *result) 40 { 41 if (attr == NULL) 42 return NULL; 43 44 struct Dwarf_CU *cu = attr->cu; 45 46 Dwarf_Off offset; 47 if (attr->form == DW_FORM_ref_addr || attr->form == DW_FORM_GNU_ref_alt 48 || attr->form == DW_FORM_ref_sup4 || attr->form == DW_FORM_ref_sup8) 49 { 50 /* This has an absolute offset. */ 51 52 uint8_t ref_size; 53 if (cu->version == 2 && attr->form == DW_FORM_ref_addr) 54 ref_size = cu->address_size; 55 else if (attr->form == DW_FORM_ref_sup4) 56 ref_size = 4; 57 else if (attr->form == DW_FORM_ref_sup8) 58 ref_size = 8; 59 else 60 ref_size = cu->offset_size; 61 62 Dwarf *dbg_ret = (attr->form == DW_FORM_GNU_ref_alt 63 ? INTUSE(dwarf_getalt) (cu->dbg) : cu->dbg); 64 65 if (dbg_ret == NULL) 66 { 67 __libdw_seterrno (DWARF_E_NO_ALT_DEBUGLINK); 68 return NULL; 69 } 70 71 if (__libdw_read_offset (cu->dbg, dbg_ret, IDX_debug_info, attr->valp, 72 ref_size, &offset, IDX_debug_info, 0)) 73 return NULL; 74 75 return INTUSE(dwarf_offdie) (dbg_ret, offset, result); 76 } 77 78 const unsigned char *datap; 79 size_t size; 80 if (attr->form == DW_FORM_ref_sig8) 81 { 82 /* This doesn't have an offset, but instead a value we 83 have to match in the type unit headers. */ 84 85 uint64_t sig = read_8ubyte_unaligned (cu->dbg, attr->valp); 86 cu = Dwarf_Sig8_Hash_find (&cu->dbg->sig8_hash, sig, NULL); 87 if (cu == NULL) 88 { 89 /* Not seen before. We have to scan through the type units. 90 Since DWARFv5 these can (also) be found in .debug_info, 91 so scan that first. */ 92 bool scan_debug_types = false; 93 do 94 { 95 cu = __libdw_intern_next_unit (attr->cu->dbg, scan_debug_types); 96 if (cu == NULL) 97 { 98 if (scan_debug_types == false) 99 scan_debug_types = true; 100 else 101 { 102 __libdw_seterrno (INTUSE(dwarf_errno) () 103 ?: DWARF_E_INVALID_REFERENCE); 104 return NULL; 105 } 106 } 107 } 108 while (cu == NULL || cu->unit_id8 != sig); 109 } 110 111 int secid = cu_sec_idx (cu); 112 datap = cu->dbg->sectiondata[secid]->d_buf; 113 size = cu->dbg->sectiondata[secid]->d_size; 114 offset = cu->start + cu->subdie_offset; 115 } 116 else 117 { 118 /* Other forms produce an offset from the CU. */ 119 if (unlikely (__libdw_formref (attr, &offset) != 0)) 120 return NULL; 121 122 datap = cu->startp; 123 size = cu->endp - cu->startp; 124 } 125 126 if (unlikely (offset >= size)) 127 { 128 __libdw_seterrno (DWARF_E_INVALID_DWARF); 129 return NULL; 130 } 131 132 memset (result, '\0', sizeof (Dwarf_Die)); 133 result->addr = (char *) datap + offset; 134 result->cu = cu; 135 return result; 136 } 137 INTDEF (dwarf_formref_die) 138
