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   Written by Ulrich Drepper <drepper@redhat.com>, 2000.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation, version 2.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program; if not, write to the Free Software Foundation,
17   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
18
19#ifdef HAVE_CONFIG_H
20# include <config.h>
21#endif
22
23#include <assert.h>
24#include <gelf.h>
25#include <string.h>
26
27#include "libelfP.h"
28
29
30GElf_Sym *
31gelf_getsymshndx (symdata, shndxdata, ndx, dst, dstshndx)
32     Elf_Data *symdata;
33     Elf_Data *shndxdata;
34     int ndx;
35     GElf_Sym *dst;
36     Elf32_Word *dstshndx;
37{
38  Elf_Data_Scn *symdata_scn = (Elf_Data_Scn *) symdata;
39  Elf_Data_Scn *shndxdata_scn = (Elf_Data_Scn *) shndxdata;
40  GElf_Sym *result = NULL;
41  Elf32_Word shndx = 0;
42
43  if (symdata == NULL)
44    return NULL;
45
46  if (unlikely (symdata->d_type != ELF_T_SYM)
47      || (likely (shndxdata_scn != NULL)
48	  && unlikely (shndxdata->d_type != ELF_T_WORD)))
49    {
50      __libelf_seterrno (ELF_E_INVALID_HANDLE);
51      return NULL;
52    }
53
54  rwlock_rdlock (symdata_scn->s->elf->lock);
55
56  /* The user is not required to pass a data descriptor for an extended
57     section index table.  */
58  if (likely (shndxdata_scn != NULL))
59    {
60      if (unlikely ((ndx + 1) * sizeof (Elf32_Word) > shndxdata_scn->d.d_size))
61	{
62	  __libelf_seterrno (ELF_E_INVALID_INDEX);
63	  goto out;
64	}
65
66      shndx = ((Elf32_Word *) shndxdata_scn->d.d_buf)[ndx];
67    }
68
69  /* This is the one place where we have to take advantage of the fact
70     that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
71     The interface is broken so that it requires this hack.  */
72  if (symdata_scn->s->elf->class == ELFCLASS32)
73    {
74      Elf32_Sym *src;
75
76      /* Here it gets a bit more complicated.  The format of the symbol
77	 table entries has to be adopted.  The user better has provided
78	 a buffer where we can store the information.  While copying the
79	 data we are converting the format.  */
80      if (unlikely ((ndx + 1) * sizeof (Elf32_Sym) > symdata->d_size))
81	{
82	  __libelf_seterrno (ELF_E_INVALID_INDEX);
83	  goto out;
84	}
85
86      src = &((Elf32_Sym *) symdata->d_buf)[ndx];
87
88      /* This might look like a simple copy operation but it's
89	 not.  There are zero- and sign-extensions going on.  */
90#define COPY(name) \
91      dst->name = src->name
92      COPY (st_name);
93      /* Please note that we can simply copy the `st_info' element since
94	 the definitions of ELFxx_ST_BIND and ELFxx_ST_TYPE are the same
95	 for the 64 bit variant.  */
96      COPY (st_info);
97      COPY (st_other);
98      COPY (st_shndx);
99      COPY (st_value);
100      COPY (st_size);
101    }
102  else
103    {
104      /* If this is a 64 bit object it's easy.  */
105      assert (sizeof (GElf_Sym) == sizeof (Elf64_Sym));
106
107      /* The data is already in the correct form.  Just make sure the
108	 index is OK.  */
109      if (unlikely ((ndx + 1) * sizeof (GElf_Sym) > symdata->d_size))
110	{
111	  __libelf_seterrno (ELF_E_INVALID_INDEX);
112	  goto out;
113	}
114
115      *dst = ((GElf_Sym *) symdata->d_buf)[ndx];
116    }
117
118  /* Now we can store the section index.  */
119  if (dstshndx != NULL)
120    *dstshndx = shndx;
121
122  result = dst;
123
124 out:
125  rwlock_unlock (symdata_scn->s->elf->lock);
126
127  return result;
128}
129