1/* Get symbol information and separate section index from symbol table
2   at the given index.
3   Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
4   This file is part of Red Hat elfutils.
5   Written by Ulrich Drepper <drepper@redhat.com>, 2000.
6
7   Red Hat elfutils is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by the
9   Free Software Foundation; version 2 of the License.
10
11   Red Hat elfutils is distributed in the hope that it will be useful, but
12   WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   General Public License for more details.
15
16   You should have received a copy of the GNU General Public License along
17   with Red Hat elfutils; if not, write to the Free Software Foundation,
18   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
19
20   In addition, as a special exception, Red Hat, Inc. gives You the
21   additional right to link the code of Red Hat elfutils with code licensed
22   under any Open Source Initiative certified open source license
23   (http://www.opensource.org/licenses/index.php) which requires the
24   distribution of source code with any binary distribution and to
25   distribute linked combinations of the two.  Non-GPL Code permitted under
26   this exception must only link to the code of Red Hat elfutils through
27   those well defined interfaces identified in the file named EXCEPTION
28   found in the source code files (the "Approved Interfaces").  The files
29   of Non-GPL Code may instantiate templates or use macros or inline
30   functions from the Approved Interfaces without causing the resulting
31   work to be covered by the GNU General Public License.  Only Red Hat,
32   Inc. may make changes or additions to the list of Approved Interfaces.
33   Red Hat's grant of this exception is conditioned upon your not adding
34   any new exceptions.  If you wish to add a new Approved Interface or
35   exception, please contact Red Hat.  You must obey the GNU General Public
36   License in all respects for all of the Red Hat elfutils code and other
37   code used in conjunction with Red Hat elfutils except the Non-GPL Code
38   covered by this exception.  If you modify this file, you may extend this
39   exception to your version of the file, but you are not obligated to do
40   so.  If you do not wish to provide this exception without modification,
41   you must delete this exception statement from your version and license
42   this file solely under the GPL without exception.
43
44   Red Hat elfutils is an included package of the Open Invention Network.
45   An included package of the Open Invention Network is a package for which
46   Open Invention Network licensees cross-license their patents.  No patent
47   license is granted, either expressly or impliedly, by designation as an
48   included package.  Should you wish to participate in the Open Invention
49   Network licensing program, please visit www.openinventionnetwork.com
50   <http://www.openinventionnetwork.com>.  */
51
52#ifdef HAVE_CONFIG_H
53# include <config.h>
54#endif
55
56#include <assert.h>
57#include <gelf.h>
58#include <string.h>
59
60#include "libelfP.h"
61
62
63GElf_Sym *
64gelf_getsymshndx (symdata, shndxdata, ndx, dst, dstshndx)
65     Elf_Data *symdata;
66     Elf_Data *shndxdata;
67     int ndx;
68     GElf_Sym *dst;
69     Elf32_Word *dstshndx;
70{
71  Elf_Data_Scn *symdata_scn = (Elf_Data_Scn *) symdata;
72  Elf_Data_Scn *shndxdata_scn = (Elf_Data_Scn *) shndxdata;
73  GElf_Sym *result = NULL;
74  Elf32_Word shndx = 0;
75
76  if (symdata == NULL)
77    return NULL;
78
79  if (unlikely (symdata->d_type != ELF_T_SYM)
80      || (likely (shndxdata_scn != NULL)
81	  && unlikely (shndxdata->d_type != ELF_T_WORD)))
82    {
83      __libelf_seterrno (ELF_E_INVALID_HANDLE);
84      return NULL;
85    }
86
87  rwlock_rdlock (symdata_scn->s->elf->lock);
88
89  /* The user is not required to pass a data descriptor for an extended
90     section index table.  */
91  if (likely (shndxdata_scn != NULL))
92    {
93      if (unlikely ((ndx + 1) * sizeof (Elf32_Word) > shndxdata_scn->d.d_size))
94	{
95	  __libelf_seterrno (ELF_E_INVALID_INDEX);
96	  goto out;
97	}
98
99      shndx = ((Elf32_Word *) shndxdata_scn->d.d_buf)[ndx];
100    }
101
102  /* This is the one place where we have to take advantage of the fact
103     that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
104     The interface is broken so that it requires this hack.  */
105  if (symdata_scn->s->elf->class == ELFCLASS32)
106    {
107      Elf32_Sym *src;
108
109      /* Here it gets a bit more complicated.  The format of the symbol
110	 table entries has to be adopted.  The user better has provided
111	 a buffer where we can store the information.  While copying the
112	 data we are converting the format.  */
113      if (unlikely ((ndx + 1) * sizeof (Elf32_Sym) > symdata->d_size))
114	{
115	  __libelf_seterrno (ELF_E_INVALID_INDEX);
116	  goto out;
117	}
118
119      src = &((Elf32_Sym *) symdata->d_buf)[ndx];
120
121      /* This might look like a simple copy operation but it's
122	 not.  There are zero- and sign-extensions going on.  */
123#define COPY(name) \
124      dst->name = src->name
125      COPY (st_name);
126      /* Please note that we can simply copy the `st_info' element since
127	 the definitions of ELFxx_ST_BIND and ELFxx_ST_TYPE are the same
128	 for the 64 bit variant.  */
129      COPY (st_info);
130      COPY (st_other);
131      COPY (st_shndx);
132      COPY (st_value);
133      COPY (st_size);
134    }
135  else
136    {
137      /* If this is a 64 bit object it's easy.  */
138      assert (sizeof (GElf_Sym) == sizeof (Elf64_Sym));
139
140      /* The data is already in the correct form.  Just make sure the
141	 index is OK.  */
142      if (unlikely ((ndx + 1) * sizeof (GElf_Sym) > symdata->d_size))
143	{
144	  __libelf_seterrno (ELF_E_INVALID_INDEX);
145	  goto out;
146	}
147
148      *dst = ((GElf_Sym *) symdata->d_buf)[ndx];
149    }
150
151  /* Now we can store the section index.  */
152  if (dstshndx != NULL)
153    *dstshndx = shndx;
154
155  result = dst;
156
157 out:
158  rwlock_unlock (symdata_scn->s->elf->lock);
159
160  return result;
161}
162