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 <[email protected]>, 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 if (valp >= endp)
92 goto invalid;
93 get_uleb128 (u128, valp, endp);
94 result = u128 + (valp - startp);
95 break;
96
97 case DW_FORM_string:
98 {
99 const unsigned char *endstrp = memchr (valp, '\0',
100 (size_t) (endp - startp));
101 if (unlikely (endstrp == NULL))
102 goto invalid;
103 result = (size_t) (endstrp - startp) + 1;
104 break;
105 }
106
107 case DW_FORM_sdata:
108 case DW_FORM_udata:
109 case DW_FORM_ref_udata:
110 case DW_FORM_addrx:
111 case DW_FORM_loclistx:
112 case DW_FORM_rnglistx:
113 case DW_FORM_strx:
114 case DW_FORM_GNU_addr_index:
115 case DW_FORM_GNU_str_index:
116 if (valp >= endp)
117 goto invalid;
118 get_uleb128 (u128, valp, endp);
119 result = valp - startp;
120 break;
121
122 case DW_FORM_indirect:
123 /* The amount of data to skip in the DIE is the size of the actual
124 FORM data (which is __libdw_form_val_len) plus the size of the
125 uleb128 encoding that FORM (which is valp - startp). */
126 if (valp >= endp)
127 goto invalid;
128 get_uleb128 (u128, valp, endp);
129 if (*valp == DW_FORM_indirect || *valp == DW_FORM_implicit_const)
130 return (size_t) -1;
131 result = __libdw_form_val_len (cu, u128, valp);
132 if (result != (size_t) -1)
133 result += valp - startp;
134 else
135 return (size_t) -1;
136 break;
137
138 default:
139 goto invalid;
140 }
141
142 if (unlikely (result > (size_t) (endp - startp)))
143 {
144 invalid:
145 __libdw_seterrno (DWARF_E_INVALID_DWARF);
146 result = (size_t) -1;
147 }
148
149 return result;
150 }
151