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
30 GElf_Sym *
gelf_getsymshndx(symdata,shndxdata,ndx,dst,dstshndx)31 gelf_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