1 /* Get symbol information and separate section index from symbol table
2 at the given index.
3 Copyright (C) 2000, 2001, 2002, 2005, 2009, 2014, 2015 Red Hat, Inc.
4 This file is part of elfutils.
5 Written by Ulrich Drepper <drepper@redhat.com>, 2000.
6
7 This file is free software; you can redistribute it and/or modify
8 it under the terms of either
9
10 * the GNU Lesser General Public License as published by the Free
11 Software Foundation; either version 3 of the License, or (at
12 your option) any later version
13
14 or
15
16 * the GNU General Public License as published by the Free
17 Software Foundation; either version 2 of the License, or (at
18 your option) any later version
19
20 or both in parallel, as here.
21
22 elfutils is distributed in the hope that it will be useful, but
23 WITHOUT ANY WARRANTY; without even the implied warranty of
24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 General Public License for more details.
26
27 You should have received copies of the GNU General Public License and
28 the GNU Lesser General Public License along with this program. If
29 not, see <http://www.gnu.org/licenses/>. */
30
31 #ifdef HAVE_CONFIG_H
32 # include <config.h>
33 #endif
34
35 #include <assert.h>
36 #include <gelf.h>
37 #include <string.h>
38
39 #include "libelfP.h"
40
41
42 GElf_Sym *
gelf_getsymshndx(Elf_Data * symdata,Elf_Data * shndxdata,int ndx,GElf_Sym * dst,Elf32_Word * dstshndx)43 gelf_getsymshndx (Elf_Data *symdata, Elf_Data *shndxdata, int ndx,
44 GElf_Sym *dst, Elf32_Word *dstshndx)
45 {
46 Elf_Data_Scn *symdata_scn = (Elf_Data_Scn *) symdata;
47 Elf_Data_Scn *shndxdata_scn = (Elf_Data_Scn *) shndxdata;
48 GElf_Sym *result = NULL;
49 Elf32_Word shndx = 0;
50
51 if (symdata == NULL)
52 return NULL;
53
54 if (unlikely (symdata->d_type != ELF_T_SYM)
55 || (likely (shndxdata_scn != NULL)
56 && unlikely (shndxdata->d_type != ELF_T_WORD)))
57 {
58 __libelf_seterrno (ELF_E_INVALID_HANDLE);
59 return NULL;
60 }
61
62 rwlock_rdlock (symdata_scn->s->elf->lock);
63
64 /* The user is not required to pass a data descriptor for an extended
65 section index table. */
66 if (likely (shndxdata_scn != NULL))
67 {
68 if (INVALID_NDX (ndx, Elf32_Word, &shndxdata_scn->d))
69 {
70 __libelf_seterrno (ELF_E_INVALID_INDEX);
71 goto out;
72 }
73
74 shndx = ((Elf32_Word *) shndxdata_scn->d.d_buf)[ndx];
75 }
76
77 /* This is the one place where we have to take advantage of the fact
78 that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
79 The interface is broken so that it requires this hack. */
80 if (symdata_scn->s->elf->class == ELFCLASS32)
81 {
82 Elf32_Sym *src;
83
84 /* Here it gets a bit more complicated. The format of the symbol
85 table entries has to be adopted. The user better has provided
86 a buffer where we can store the information. While copying the
87 data we are converting the format. */
88 if (INVALID_NDX (ndx, Elf32_Sym, symdata))
89 {
90 __libelf_seterrno (ELF_E_INVALID_INDEX);
91 goto out;
92 }
93
94 src = &((Elf32_Sym *) symdata->d_buf)[ndx];
95
96 /* This might look like a simple copy operation but it's
97 not. There are zero- and sign-extensions going on. */
98 #define COPY(name) \
99 dst->name = src->name
100 COPY (st_name);
101 /* Please note that we can simply copy the `st_info' element since
102 the definitions of ELFxx_ST_BIND and ELFxx_ST_TYPE are the same
103 for the 64 bit variant. */
104 COPY (st_info);
105 COPY (st_other);
106 COPY (st_shndx);
107 COPY (st_value);
108 COPY (st_size);
109 }
110 else
111 {
112 /* If this is a 64 bit object it's easy. */
113 assert (sizeof (GElf_Sym) == sizeof (Elf64_Sym));
114
115 /* The data is already in the correct form. Just make sure the
116 index is OK. */
117 if (INVALID_NDX (ndx, GElf_Sym, symdata))
118 {
119 __libelf_seterrno (ELF_E_INVALID_INDEX);
120 goto out;
121 }
122
123 *dst = ((GElf_Sym *) symdata->d_buf)[ndx];
124 }
125
126 /* Now we can store the section index. */
127 if (dstshndx != NULL)
128 *dstshndx = shndx;
129
130 result = dst;
131
132 out:
133 rwlock_unlock (symdata_scn->s->elf->lock);
134
135 return result;
136 }
137