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
40size_t
41internal_function
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_sec_offset:
64    case DW_FORM_GNU_ref_alt:
65    case DW_FORM_GNU_strp_alt:
66      result = cu->offset_size;
67      break;
68
69    case DW_FORM_block1:
70      if (unlikely ((size_t) (endp - startp) < 1))
71	goto invalid;
72      result = *valp + 1;
73      break;
74
75    case DW_FORM_block2:
76      if (unlikely ((size_t) (endp - startp) < 2))
77	goto invalid;
78      result = read_2ubyte_unaligned (cu->dbg, valp) + 2;
79      break;
80
81    case DW_FORM_block4:
82      if (unlikely ((size_t) (endp - startp) < 4))
83	goto invalid;
84      result = read_4ubyte_unaligned (cu->dbg, valp) + 4;
85      break;
86
87    case DW_FORM_block:
88    case DW_FORM_exprloc:
89      get_uleb128 (u128, valp, endp);
90      result = u128 + (valp - startp);
91      break;
92
93    case DW_FORM_string:
94      {
95	const unsigned char *endstrp = memchr (valp, '\0',
96					       (size_t) (endp - startp));
97	if (unlikely (endstrp == NULL))
98	  goto invalid;
99	result = (size_t) (endstrp - startp) + 1;
100	break;
101      }
102
103    case DW_FORM_sdata:
104    case DW_FORM_udata:
105    case DW_FORM_ref_udata:
106      get_uleb128 (u128, valp, endp);
107      result = valp - startp;
108      break;
109
110    case DW_FORM_indirect:
111      get_uleb128 (u128, valp, endp);
112      // XXX Is this really correct?
113      result = __libdw_form_val_len (cu, u128, valp);
114      if (result != (size_t) -1)
115	result += valp - startp;
116      else
117        return (size_t) -1;
118      break;
119
120    default:
121      goto invalid;
122    }
123
124  if (unlikely (result > (size_t) (endp - startp)))
125    {
126    invalid:
127      __libdw_seterrno (DWARF_E_INVALID_DWARF);
128      result = (size_t) -1;
129    }
130
131  return result;
132}
133