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/* Check that every die that has a linkage_name is also external.
Copyright (C) 2011 Red Hat, Inc.
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
elfutils is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "check_die_tree.hh"
#include "pri.hh"
#include "messages.hh"
#include "../libelf/gelf.h"
#include "../libdw/libdw.h"
using elfutils::dwarf;
namespace
{
class check_linkage_external_die
: public die_check
{
private:
std::map<std::string, bool> _m_symbols;
public:
static checkdescriptor const *descriptor ()
{
static checkdescriptor cd
(checkdescriptor::create ("check_linkage_external_die")
.description ("Check that each DIE that has a linkage_name "
"also has an external attribute.\n"));
return &cd;
}
check_linkage_external_die (highlevel_check_i *check,
checkstack &, dwarflint &)
{
// Extract all symbol table names for objects and functions
// and store whether they are global or not in _m_symbols.
Dwarf *dwarf = check->c_dw;
Elf *elf = dwarf_getelf (dwarf);
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (elf, scn)) != NULL)
{
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr != NULL && (shdr->sh_type == SHT_DYNSYM
|| shdr->sh_type == SHT_SYMTAB))
{
Elf_Data *data = elf_getdata (scn, NULL);
size_t shstrndx;
elf_getshdrstrndx (elf, &shstrndx);
unsigned int syms = shdr->sh_size / shdr->sh_entsize;
for (unsigned int cnt = 0; cnt < syms; ++cnt)
{
GElf_Sym sym_mem;
GElf_Sym *sym = gelf_getsym (data, cnt, &sym_mem);
if (sym != NULL
&& (GELF_ST_TYPE (sym->st_info) == STT_OBJECT
|| GELF_ST_TYPE (sym->st_info) == STT_FUNC))
{
const char *name;
name = elf_strptr (elf, shdr->sh_link, sym->st_name);
if (name != NULL)
{
// Regard anything not explicitly marked as local
// a global symbol, it could be STB_GLOBAL,
// STB_WEAK, STB_GNU_UNIQUE, ...
unsigned int binding = GELF_ST_BIND (sym->st_info);
bool global = binding != STB_LOCAL;
using namespace std;
_m_symbols.insert (pair<string, bool>
(string (name), global));
}
}
}
}
}
}
static bool is_external (all_dies_iterator<dwarf> const &it)
{
dwarf::debug_info_entry::attributes_type attrs = (*it).attributes ();
dwarf::debug_info_entry::attributes_type::const_iterator external
= attrs.find_integrate (DW_AT_external);
return external != attrs.end () && (*external).second.flag ();
}
virtual void
die (all_dies_iterator<dwarf> const &it)
{
dwarf::debug_info_entry const &entry = *it;
dwarf::debug_info_entry::attributes_type attrs = entry.attributes ();
dwarf::debug_info_entry::attributes_type::const_iterator linkage_name
= attrs.find (DW_AT_linkage_name);
if (linkage_name == attrs.end ())
linkage_name = attrs.find (DW_AT_MIPS_linkage_name);
if (linkage_name != attrs.end ())
{
using namespace std;
const char *name = (*linkage_name).second.string ();
map<string, bool>::iterator s = _m_symbols.find (string (name));
if (s == _m_symbols.end ())
{
// No symbol in table, OK, if not a defining or const object.
// GNU extension, anonymous structs, enums and unions can
// have a linkage_name.
if (attrs.find (DW_AT_declaration) == attrs.end ()
&& attrs.find (DW_AT_const_value) == attrs.end ()
&& ((entry.tag () != DW_TAG_structure_type
&& entry.tag () != DW_TAG_enumeration_type
&& entry.tag () != DW_TAG_union_type)
|| attrs.find (DW_AT_name) != attrs.end ()))
{
wr_message (die_locus (entry),
mc_impact_3 | mc_acc_suboptimal | mc_die_other)
.id (descriptor ())
<< elfutils::dwarf::tags::name (entry.tag ())
<< " has linkage_name attribute `"
<< name << "', which is not in string table,"
<< " but DIE is not marked as a declaration"
<< " or const value."
<< std::endl;
}
}
else if ((*s).second == false)
{
// Local symbol in table, OK if not a defining object
// and marked external. Which means it comes from an
// external symbol table.
if (attrs.find (DW_AT_declaration) == attrs.end ()
&& is_external (it))
{
wr_message (die_locus (entry),
mc_impact_3 | mc_acc_suboptimal | mc_die_other)
.id (descriptor ())
<< elfutils::dwarf::tags::name (entry.tag ())
<< " has linkage_name attribute `"
<< name << "', which is a local symbol."
<< std::endl;
}
}
else if (! is_external (it))
{
// Global symbol in symbol table, not marked external.
// Always bad.
wr_message (die_locus (entry),
mc_impact_3 | mc_acc_suboptimal | mc_die_other)
.id (descriptor ())
<< elfutils::dwarf::tags::name (entry.tag ())
<< " has linkage_name attribute, but no external attribute."
<< std::endl;
}
}
}
};
reg_die_check<check_linkage_external_die> reg;
}
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