1 /* Return string associated with given attribute.
2 Copyright (C) 2003-2010, 2013, 2017, 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 <dwarf.h>
34 #include "libdwP.h"
35
36
37 const char *
dwarf_formstring(Dwarf_Attribute * attrp)38 dwarf_formstring (Dwarf_Attribute *attrp)
39 {
40 /* Ignore earlier errors. */
41 if (attrp == NULL)
42 return NULL;
43
44 /* We found it. Now determine where the string is stored. */
45 if (attrp->form == DW_FORM_string)
46 /* A simple inlined string. */
47 return (const char *) attrp->valp;
48
49 Dwarf_CU *cu = attrp->cu;
50 Dwarf *dbg = cu->dbg;
51 Dwarf *dbg_ret = ((attrp->form == DW_FORM_GNU_strp_alt
52 || attrp->form == DW_FORM_strp_sup)
53 ? INTUSE(dwarf_getalt) (dbg) : dbg);
54
55 if (unlikely (dbg_ret == NULL))
56 {
57 __libdw_seterrno (DWARF_E_NO_ALT_DEBUGLINK);
58 return NULL;
59 }
60
61 Elf_Data *data = ((attrp->form == DW_FORM_line_strp)
62 ? dbg_ret->sectiondata[IDX_debug_line_str]
63 : dbg_ret->sectiondata[IDX_debug_str]);
64 if (data == NULL)
65 {
66 __libdw_seterrno ((attrp->form == DW_FORM_line_strp)
67 ? DWARF_E_NO_DEBUG_LINE_STR
68 : DWARF_E_NO_DEBUG_STR);
69 return NULL;
70 }
71
72 uint64_t off;
73 if (attrp->form == DW_FORM_strp
74 || attrp->form == DW_FORM_GNU_strp_alt
75 || attrp->form == DW_FORM_strp_sup)
76 {
77 if (__libdw_read_offset (dbg, dbg_ret, cu_sec_idx (cu),
78 attrp->valp, cu->offset_size, &off,
79 IDX_debug_str, 1))
80 return NULL;
81 }
82 else if (attrp->form == DW_FORM_line_strp)
83 {
84 if (__libdw_read_offset (dbg, dbg_ret, cu_sec_idx (cu),
85 attrp->valp, cu->offset_size, &off,
86 IDX_debug_line_str, 1))
87 return NULL;
88 }
89 else
90 {
91 Dwarf_Word idx;
92 const unsigned char *datap = attrp->valp;
93 const unsigned char *endp = cu->endp;
94 switch (attrp->form)
95 {
96 case DW_FORM_strx:
97 case DW_FORM_GNU_str_index:
98 if (datap >= endp)
99 {
100 invalid:
101 __libdw_seterrno (DWARF_E_INVALID_DWARF);
102 return NULL;
103 }
104 get_uleb128 (idx, datap, endp);
105 break;
106
107 case DW_FORM_strx1:
108 if (datap >= endp - 1)
109 goto invalid;
110 idx = *datap;
111 break;
112
113 case DW_FORM_strx2:
114 if (datap >= endp - 2)
115 goto invalid;
116 idx = read_2ubyte_unaligned (dbg, datap);
117 break;
118
119 case DW_FORM_strx3:
120 if (datap >= endp - 3)
121 goto invalid;
122 idx = read_3ubyte_unaligned (dbg, datap);
123 break;
124
125 case DW_FORM_strx4:
126 if (datap >= endp - 4)
127 goto invalid;
128 idx = read_4ubyte_unaligned (dbg, datap);
129 break;
130
131 default:
132 __libdw_seterrno (DWARF_E_NO_STRING);
133 return NULL;
134 }
135
136 /* So we got an index in the .debug_str_offsets. Lets see if it
137 is valid and we can get the actual .debug_str offset. */
138 Dwarf_Off str_off = __libdw_cu_str_off_base (cu);
139 if (str_off == (Dwarf_Off) -1)
140 return NULL;
141
142 if (dbg->sectiondata[IDX_debug_str_offsets] == NULL)
143 {
144 __libdw_seterrno (DWARF_E_NO_STR_OFFSETS);
145 return NULL;
146 }
147
148 /* The section should at least contain room for one offset. */
149 int offset_size = cu->offset_size;
150 if (cu->offset_size > dbg->sectiondata[IDX_debug_str_offsets]->d_size)
151 {
152 invalid_offset:
153 __libdw_seterrno (DWARF_E_INVALID_OFFSET);
154 return NULL;
155 }
156
157 /* And the base offset should be at least inside the section. */
158 if (str_off > (dbg->sectiondata[IDX_debug_str_offsets]->d_size
159 - offset_size))
160 goto invalid_offset;
161
162 size_t max_idx = (dbg->sectiondata[IDX_debug_str_offsets]->d_size
163 - offset_size - str_off) / offset_size;
164 if (idx > max_idx)
165 goto invalid_offset;
166
167 datap = (dbg->sectiondata[IDX_debug_str_offsets]->d_buf
168 + str_off + (idx * offset_size));
169 if (offset_size == 4)
170 off = read_4ubyte_unaligned (dbg, datap);
171 else
172 off = read_8ubyte_unaligned (dbg, datap);
173
174 if (off > dbg->sectiondata[IDX_debug_str]->d_size)
175 goto invalid_offset;
176 }
177
178 return (const char *) data->d_buf + off;
179 }
180 INTDEF(dwarf_formstring)
181