1 /* Return child of current DIE. 2 Copyright (C) 2003-2011, 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 "libdwP.h" 35 #include <string.h> 36 37 /* Some arbitrary value not conflicting with any existing code. */ 38 #define INVALID 0xffffe444 39 40 41 unsigned char * 42 internal_function 43 __libdw_find_attr (Dwarf_Die *die, unsigned int search_name, 44 unsigned int *codep, unsigned int *formp) 45 { 46 Dwarf *dbg = die->cu->dbg; 47 const unsigned char *readp; 48 49 /* Find the abbreviation entry. */ 50 Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, &readp); 51 if (unlikely (abbrevp == DWARF_END_ABBREV)) 52 { 53 invalid_dwarf: 54 __libdw_seterrno (DWARF_E_INVALID_DWARF); 55 return NULL; 56 } 57 58 /* Search the name attribute. */ 59 unsigned char *const endp 60 = ((unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf 61 + dbg->sectiondata[IDX_debug_abbrev]->d_size); 62 63 const unsigned char *attrp = abbrevp->attrp; 64 while (1) 65 { 66 /* Get attribute name and form. */ 67 if (unlikely (attrp >= endp)) 68 goto invalid_dwarf; 69 unsigned int attr_name; 70 get_uleb128 (attr_name, attrp, endp); 71 72 if (unlikely (attrp >= endp)) 73 goto invalid_dwarf; 74 unsigned int attr_form; 75 get_uleb128 (attr_form, attrp, endp); 76 77 /* We can stop if we found the attribute with value zero. */ 78 if (attr_name == 0 && attr_form == 0) 79 break; 80 81 /* Is this the name attribute? */ 82 if (attr_name == search_name && search_name != INVALID) 83 { 84 if (codep != NULL) 85 *codep = attr_name; 86 if (formp != NULL) 87 *formp = attr_form; 88 89 return (unsigned char *) readp; 90 } 91 92 /* Skip over the rest of this attribute (if there is any). */ 93 if (attr_form != 0) 94 { 95 size_t len = __libdw_form_val_len (die->cu, attr_form, readp); 96 if (unlikely (len == (size_t) -1l)) 97 { 98 readp = NULL; 99 break; 100 } 101 102 // __libdw_form_val_len will have done a bounds check. 103 readp += len; 104 } 105 } 106 107 // XXX Do we need other values? 108 if (codep != NULL) 109 *codep = INVALID; 110 if (formp != NULL) 111 *formp = INVALID; 112 113 return (unsigned char *) readp; 114 } 115 116 117 int 118 dwarf_child (Dwarf_Die *die, Dwarf_Die *result) 119 { 120 /* Ignore previous errors. */ 121 if (die == NULL) 122 return -1; 123 124 /* Find the abbreviation entry. */ 125 Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, NULL); 126 if (unlikely (abbrevp == DWARF_END_ABBREV)) 127 { 128 __libdw_seterrno (DWARF_E_INVALID_DWARF); 129 return -1; 130 } 131 132 /* If there are no children, do not search. */ 133 if (! abbrevp->has_children) 134 return 1; 135 136 /* Skip past the last attribute. */ 137 void *addr = __libdw_find_attr (die, INVALID, NULL, NULL); 138 139 if (addr == NULL) 140 return -1; 141 142 /* RESULT can be the same as DIE. So preserve what we need. */ 143 struct Dwarf_CU *cu = die->cu; 144 145 /* It's kosher (just suboptimal) to have a null entry first thing (7.5.3). 146 So if this starts with ULEB128 of 0 (even with silly encoding of 0), 147 it is a kosher null entry and we do not really have any children. */ 148 const unsigned char *code = addr; 149 const unsigned char *endp = cu->endp; 150 while (1) 151 { 152 if (unlikely (code >= endp)) /* Truncated section. */ 153 return 1; 154 if (unlikely (*code == 0x80)) 155 ++code; 156 else 157 break; 158 } 159 if (unlikely (*code == '\0')) 160 return 1; 161 162 /* Clear the entire DIE structure. This signals we have not yet 163 determined any of the information. */ 164 memset (result, '\0', sizeof (Dwarf_Die)); 165 166 /* We have the address. */ 167 result->addr = addr; 168 169 /* Same CU as the parent. */ 170 result->cu = cu; 171 172 return 0; 173 } 174 INTDEF(dwarf_child) 175
