1 /* Find debugging and symbol information for a module in libdwfl.
2 Copyright (C) 2006-2010 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4
5 Red Hat elfutils is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by the
7 Free Software Foundation; version 2 of the License.
8
9 Red Hat elfutils is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with Red Hat elfutils; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18 In addition, as a special exception, Red Hat, Inc. gives You the
19 additional right to link the code of Red Hat elfutils with code licensed
20 under any Open Source Initiative certified open source license
21 (http://www.opensource.org/licenses/index.php) which requires the
22 distribution of source code with any binary distribution and to
23 distribute linked combinations of the two. Non-GPL Code permitted under
24 this exception must only link to the code of Red Hat elfutils through
25 those well defined interfaces identified in the file named EXCEPTION
26 found in the source code files (the "Approved Interfaces"). The files
27 of Non-GPL Code may instantiate templates or use macros or inline
28 functions from the Approved Interfaces without causing the resulting
29 work to be covered by the GNU General Public License. Only Red Hat,
30 Inc. may make changes or additions to the list of Approved Interfaces.
31 Red Hat's grant of this exception is conditioned upon your not adding
32 any new exceptions. If you wish to add a new Approved Interface or
33 exception, please contact Red Hat. You must obey the GNU General Public
34 License in all respects for all of the Red Hat elfutils code and other
35 code used in conjunction with Red Hat elfutils except the Non-GPL Code
36 covered by this exception. If you modify this file, you may extend this
37 exception to your version of the file, but you are not obligated to do
38 so. If you do not wish to provide this exception without modification,
39 you must delete this exception statement from your version and license
40 this file solely under the GPL without exception.
41
42 Red Hat elfutils is an included package of the Open Invention Network.
43 An included package of the Open Invention Network is a package for which
44 Open Invention Network licensees cross-license their patents. No patent
45 license is granted, either expressly or impliedly, by designation as an
46 included package. Should you wish to participate in the Open Invention
47 Network licensing program, please visit www.openinventionnetwork.com
48 <http://www.openinventionnetwork.com>. */
49
50 #include "libdwflP.h"
51
52 const char *
dwfl_module_getsym(Dwfl_Module * mod,int ndx,GElf_Sym * sym,GElf_Word * shndxp)53 dwfl_module_getsym (Dwfl_Module *mod, int ndx,
54 GElf_Sym *sym, GElf_Word *shndxp)
55 {
56 if (unlikely (mod == NULL))
57 return NULL;
58
59 if (unlikely (mod->symdata == NULL))
60 {
61 int result = INTUSE(dwfl_module_getsymtab) (mod);
62 if (result < 0)
63 return NULL;
64 }
65
66 GElf_Word shndx;
67 sym = gelf_getsymshndx (mod->symdata, mod->symxndxdata, ndx, sym, &shndx);
68 if (unlikely (sym == NULL))
69 {
70 __libdwfl_seterrno (DWFL_E_LIBELF);
71 return NULL;
72 }
73
74 if (sym->st_shndx != SHN_XINDEX)
75 shndx = sym->st_shndx;
76
77 /* Figure out whether this symbol points into an SHF_ALLOC section. */
78 bool alloc = true;
79 if ((shndxp != NULL || mod->e_type != ET_REL)
80 && (sym->st_shndx == SHN_XINDEX
81 || (sym->st_shndx < SHN_LORESERVE && sym->st_shndx != SHN_UNDEF)))
82 {
83 GElf_Shdr shdr_mem;
84 GElf_Shdr *shdr = gelf_getshdr (elf_getscn (mod->symfile->elf, shndx),
85 &shdr_mem);
86 alloc = unlikely (shdr == NULL) || (shdr->sh_flags & SHF_ALLOC);
87 }
88
89 if (shndxp != NULL)
90 /* Yield -1 in case of a non-SHF_ALLOC section. */
91 *shndxp = alloc ? shndx : (GElf_Word) -1;
92
93 switch (sym->st_shndx)
94 {
95 case SHN_ABS: /* XXX sometimes should use bias?? */
96 case SHN_UNDEF:
97 case SHN_COMMON:
98 break;
99
100 default:
101 if (mod->e_type == ET_REL)
102 {
103 /* In an ET_REL file, the symbol table values are relative
104 to the section, not to the module's load base. */
105 size_t symshstrndx = SHN_UNDEF;
106 Dwfl_Error result = __libdwfl_relocate_value (mod, mod->symfile->elf,
107 &symshstrndx,
108 shndx, &sym->st_value);
109 if (unlikely (result != DWFL_E_NOERROR))
110 {
111 __libdwfl_seterrno (result);
112 return NULL;
113 }
114 }
115 else if (alloc)
116 /* Apply the bias to the symbol value. */
117 sym->st_value = dwfl_adjusted_st_value (mod, sym->st_value);
118 break;
119 }
120
121 if (unlikely (sym->st_name >= mod->symstrdata->d_size))
122 {
123 __libdwfl_seterrno (DWFL_E_BADSTROFF);
124 return NULL;
125 }
126 return (const char *) mod->symstrdata->d_buf + sym->st_name;
127 }
128 INTDEF (dwfl_module_getsym)
129