1 /* Look up the DIE in a reference-form attribute. 2 Copyright (C) 2005-2010 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 { 49 /* This has an absolute offset. */ 50 51 uint8_t ref_size = (cu->version == 2 && attr->form == DW_FORM_ref_addr 52 ? cu->address_size 53 : cu->offset_size); 54 55 Dwarf *dbg_ret = (attr->form == DW_FORM_GNU_ref_alt 56 ? cu->dbg->alt_dwarf : cu->dbg); 57 58 if (dbg_ret == NULL) 59 { 60 __libdw_seterrno (DWARF_E_NO_ALT_DEBUGLINK); 61 return NULL; 62 } 63 64 if (__libdw_read_offset (cu->dbg, dbg_ret, IDX_debug_info, attr->valp, 65 ref_size, &offset, IDX_debug_info, 0)) 66 return NULL; 67 68 return INTUSE(dwarf_offdie) (dbg_ret, offset, result); 69 } 70 71 const unsigned char *datap; 72 size_t size; 73 if (attr->form == DW_FORM_ref_sig8) 74 { 75 /* This doesn't have an offset, but instead a value we 76 have to match in the .debug_types type unit headers. */ 77 78 uint64_t sig = read_8ubyte_unaligned (cu->dbg, attr->valp); 79 cu = Dwarf_Sig8_Hash_find (&cu->dbg->sig8_hash, sig, NULL); 80 if (cu == NULL) 81 /* Not seen before. We have to scan through the type units. */ 82 do 83 { 84 cu = __libdw_intern_next_unit (attr->cu->dbg, true); 85 if (cu == NULL) 86 { 87 __libdw_seterrno (INTUSE(dwarf_errno) () 88 ?: DWARF_E_INVALID_REFERENCE); 89 return NULL; 90 } 91 } 92 while (cu->type_sig8 != sig); 93 94 datap = cu->dbg->sectiondata[IDX_debug_types]->d_buf; 95 size = cu->dbg->sectiondata[IDX_debug_types]->d_size; 96 offset = cu->start + cu->type_offset; 97 } 98 else 99 { 100 /* Other forms produce an offset from the CU. */ 101 if (unlikely (__libdw_formref (attr, &offset) != 0)) 102 return NULL; 103 104 datap = cu->startp; 105 size = cu->endp - cu->startp; 106 } 107 108 if (unlikely (offset >= size)) 109 { 110 __libdw_seterrno (DWARF_E_INVALID_DWARF); 111 return NULL; 112 } 113 114 memset (result, '\0', sizeof (Dwarf_Die)); 115 result->addr = (char *) datap + offset; 116 result->cu = cu; 117 return result; 118 } 119 INTDEF (dwarf_formref_die) 120
