1 /* Helper functions for form handling.
2 Copyright (C) 2003-2009, 2014 Red Hat, Inc.
3 This file is part of elfutils.
4 Written by Ulrich Drepper <drepper@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 <string.h>
36
37 #include "libdwP.h"
38
39
40 size_t
41 internal_function
__libdw_form_val_compute_len(struct Dwarf_CU * cu,unsigned int form,const unsigned char * valp)42 __libdw_form_val_compute_len (struct Dwarf_CU *cu, unsigned int form,
43 const unsigned char *valp)
44 {
45 const unsigned char *startp = valp;
46 const unsigned char *endp = cu->endp;
47 Dwarf_Word u128;
48 size_t result;
49
50 /* NB: This doesn't cover constant form lengths, which are
51 already handled by the inlined __libdw_form_val_len. */
52 switch (form)
53 {
54 case DW_FORM_addr:
55 result = cu->address_size;
56 break;
57
58 case DW_FORM_ref_addr:
59 result = cu->version == 2 ? cu->address_size : cu->offset_size;
60 break;
61
62 case DW_FORM_strp:
63 case DW_FORM_strp_sup:
64 case DW_FORM_line_strp:
65 case DW_FORM_sec_offset:
66 case DW_FORM_GNU_ref_alt:
67 case DW_FORM_GNU_strp_alt:
68 result = cu->offset_size;
69 break;
70
71 case DW_FORM_block1:
72 if (unlikely ((size_t) (endp - startp) < 1))
73 goto invalid;
74 result = *valp + 1;
75 break;
76
77 case DW_FORM_block2:
78 if (unlikely ((size_t) (endp - startp) < 2))
79 goto invalid;
80 result = read_2ubyte_unaligned (cu->dbg, valp) + 2;
81 break;
82
83 case DW_FORM_block4:
84 if (unlikely ((size_t) (endp - startp) < 4))
85 goto invalid;
86 result = read_4ubyte_unaligned (cu->dbg, valp) + 4;
87 break;
88
89 case DW_FORM_block:
90 case DW_FORM_exprloc:
91 get_uleb128 (u128, valp, endp);
92 result = u128 + (valp - startp);
93 break;
94
95 case DW_FORM_string:
96 {
97 const unsigned char *endstrp = memchr (valp, '\0',
98 (size_t) (endp - startp));
99 if (unlikely (endstrp == NULL))
100 goto invalid;
101 result = (size_t) (endstrp - startp) + 1;
102 break;
103 }
104
105 case DW_FORM_sdata:
106 case DW_FORM_udata:
107 case DW_FORM_ref_udata:
108 case DW_FORM_addrx:
109 case DW_FORM_loclistx:
110 case DW_FORM_rnglistx:
111 case DW_FORM_strx:
112 case DW_FORM_GNU_addr_index:
113 case DW_FORM_GNU_str_index:
114 get_uleb128 (u128, valp, endp);
115 result = valp - startp;
116 break;
117
118 case DW_FORM_indirect:
119 /* The amount of data to skip in the DIE is the size of the actual
120 FORM data (which is __libdw_form_val_len) plus the size of the
121 uleb128 encoding that FORM (which is valp - startp). */
122 get_uleb128 (u128, valp, endp);
123 if (*valp == DW_FORM_indirect || *valp == DW_FORM_implicit_const)
124 return (size_t) -1;
125 result = __libdw_form_val_len (cu, u128, valp);
126 if (result != (size_t) -1)
127 result += valp - startp;
128 else
129 return (size_t) -1;
130 break;
131
132 default:
133 goto invalid;
134 }
135
136 if (unlikely (result > (size_t) (endp - startp)))
137 {
138 invalid:
139 __libdw_seterrno (DWARF_E_INVALID_DWARF);
140 result = (size_t) -1;
141 }
142
143 return result;
144 }
145