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binutils-gdb/gold/object.cc
Ian Lance Taylor f2619d6c3b Initialize variable to avoid warning.
2007-12-06 06:03:00 +00:00

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// object.cc -- support for an object file for linking in gold
// Copyright 2006, 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program 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.
// This program 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, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include <cerrno>
#include <cstring>
#include <cstdarg>
#include "demangle.h"
#include "libiberty.h"
#include "target-select.h"
#include "dwarf_reader.h"
#include "layout.h"
#include "output.h"
#include "symtab.h"
#include "reloc.h"
#include "object.h"
#include "dynobj.h"
namespace gold
{
// Class Object.
// Set the target based on fields in the ELF file header.
void
Object::set_target(int machine, int size, bool big_endian, int osabi,
int abiversion)
{
Target* target = select_target(machine, size, big_endian, osabi, abiversion);
if (target == NULL)
gold_fatal(_("%s: unsupported ELF machine number %d"),
this->name().c_str(), machine);
this->target_ = target;
}
// Report an error for this object file. This is used by the
// elfcpp::Elf_file interface, and also called by the Object code
// itself.
void
Object::error(const char* format, ...) const
{
va_list args;
va_start(args, format);
char* buf = NULL;
if (vasprintf(&buf, format, args) < 0)
gold_nomem();
va_end(args);
gold_error(_("%s: %s"), this->name().c_str(), buf);
free(buf);
}
// Return a view of the contents of a section.
const unsigned char*
Object::section_contents(unsigned int shndx, off_t* plen, bool cache)
{
Location loc(this->do_section_contents(shndx));
*plen = loc.data_size;
return this->get_view(loc.file_offset, loc.data_size, cache);
}
// Read the section data into SD. This is code common to Sized_relobj
// and Sized_dynobj, so we put it into Object.
template<int size, bool big_endian>
void
Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
Read_symbols_data* sd)
{
const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
// Read the section headers.
const off_t shoff = elf_file->shoff();
const unsigned int shnum = this->shnum();
sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size, true);
// Read the section names.
const unsigned char* pshdrs = sd->section_headers->data();
const unsigned char* pshdrnames = pshdrs + elf_file->shstrndx() * shdr_size;
typename elfcpp::Shdr<size, big_endian> shdrnames(pshdrnames);
if (shdrnames.get_sh_type() != elfcpp::SHT_STRTAB)
this->error(_("section name section has wrong type: %u"),
static_cast<unsigned int>(shdrnames.get_sh_type()));
sd->section_names_size = shdrnames.get_sh_size();
sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(),
sd->section_names_size, false);
}
// If NAME is the name of a special .gnu.warning section, arrange for
// the warning to be issued. SHNDX is the section index. Return
// whether it is a warning section.
bool
Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
Symbol_table* symtab)
{
const char warn_prefix[] = ".gnu.warning.";
const int warn_prefix_len = sizeof warn_prefix - 1;
if (strncmp(name, warn_prefix, warn_prefix_len) == 0)
{
symtab->add_warning(name + warn_prefix_len, this, shndx);
return true;
}
return false;
}
// Class Sized_relobj.
template<int size, bool big_endian>
Sized_relobj<size, big_endian>::Sized_relobj(
const std::string& name,
Input_file* input_file,
off_t offset,
const elfcpp::Ehdr<size, big_endian>& ehdr)
: Relobj(name, input_file, offset),
elf_file_(this, ehdr),
symtab_shndx_(-1U),
local_symbol_count_(0),
output_local_symbol_count_(0),
output_local_dynsym_count_(0),
symbols_(),
local_symbol_offset_(0),
local_dynsym_offset_(0),
local_values_(),
local_got_offsets_(),
has_eh_frame_(false)
{
}
template<int size, bool big_endian>
Sized_relobj<size, big_endian>::~Sized_relobj()
{
}
// Set up an object file based on the file header. This sets up the
// target and reads the section information.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::setup(
const elfcpp::Ehdr<size, big_endian>& ehdr)
{
this->set_target(ehdr.get_e_machine(), size, big_endian,
ehdr.get_e_ident()[elfcpp::EI_OSABI],
ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
const unsigned int shnum = this->elf_file_.shnum();
this->set_shnum(shnum);
}
// Find the SHT_SYMTAB section, given the section headers. The ELF
// standard says that maybe in the future there can be more than one
// SHT_SYMTAB section. Until somebody figures out how that could
// work, we assume there is only one.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::find_symtab(const unsigned char* pshdrs)
{
const unsigned int shnum = this->shnum();
this->symtab_shndx_ = 0;
if (shnum > 0)
{
// Look through the sections in reverse order, since gas tends
// to put the symbol table at the end.
const unsigned char* p = pshdrs + shnum * This::shdr_size;
unsigned int i = shnum;
while (i > 0)
{
--i;
p -= This::shdr_size;
typename This::Shdr shdr(p);
if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB)
{
this->symtab_shndx_ = i;
break;
}
}
}
}
// Return whether SHDR has the right type and flags to be a GNU
// .eh_frame section.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::check_eh_frame_flags(
const elfcpp::Shdr<size, big_endian>* shdr) const
{
return (shdr->get_sh_size() > 0
&& shdr->get_sh_type() == elfcpp::SHT_PROGBITS
&& shdr->get_sh_flags() == elfcpp::SHF_ALLOC);
}
// Return whether there is a GNU .eh_frame section, given the section
// headers and the section names.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::find_eh_frame(const unsigned char* pshdrs,
const char* names,
off_t names_size) const
{
const unsigned int shnum = this->shnum();
const unsigned char* p = pshdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
{
typename This::Shdr shdr(p);
if (this->check_eh_frame_flags(&shdr))
{
if (shdr.get_sh_name() >= names_size)
{
this->error(_("bad section name offset for section %u: %lu"),
i, static_cast<unsigned long>(shdr.get_sh_name()));
continue;
}
const char* name = names + shdr.get_sh_name();
if (strcmp(name, ".eh_frame") == 0)
return true;
}
}
return false;
}
// Read the sections and symbols from an object file.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
{
this->read_section_data(&this->elf_file_, sd);
const unsigned char* const pshdrs = sd->section_headers->data();
this->find_symtab(pshdrs);
const unsigned char* namesu = sd->section_names->data();
const char* names = reinterpret_cast<const char*>(namesu);
if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
this->has_eh_frame_ = true;
sd->symbols = NULL;
sd->symbols_size = 0;
sd->external_symbols_offset = 0;
sd->symbol_names = NULL;
sd->symbol_names_size = 0;
if (this->symtab_shndx_ == 0)
{
// No symbol table. Weird but legal.
return;
}
// Get the symbol table section header.
typename This::Shdr symtabshdr(pshdrs
+ this->symtab_shndx_ * This::shdr_size);
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
// If this object has a .eh_frame section, we need all the symbols.
// Otherwise we only need the external symbols. While it would be
// simpler to just always read all the symbols, I've seen object
// files with well over 2000 local symbols, which for a 64-bit
// object file format is over 5 pages that we don't need to read
// now.
const int sym_size = This::sym_size;
const unsigned int loccount = symtabshdr.get_sh_info();
this->local_symbol_count_ = loccount;
this->local_values_.resize(loccount);
off_t locsize = loccount * sym_size;
off_t dataoff = symtabshdr.get_sh_offset();
off_t datasize = symtabshdr.get_sh_size();
off_t extoff = dataoff + locsize;
off_t extsize = datasize - locsize;
off_t readoff = this->has_eh_frame_ ? dataoff : extoff;
off_t readsize = this->has_eh_frame_ ? datasize : extsize;
File_view* fvsymtab = this->get_lasting_view(readoff, readsize, false);
// Read the section header for the symbol names.
unsigned int strtab_shndx = symtabshdr.get_sh_link();
if (strtab_shndx >= this->shnum())
{
this->error(_("invalid symbol table name index: %u"), strtab_shndx);
return;
}
typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
{
this->error(_("symbol table name section has wrong type: %u"),
static_cast<unsigned int>(strtabshdr.get_sh_type()));
return;
}
// Read the symbol names.
File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(),
strtabshdr.get_sh_size(), true);
sd->symbols = fvsymtab;
sd->symbols_size = readsize;
sd->external_symbols_offset = this->has_eh_frame_ ? locsize : 0;
sd->symbol_names = fvstrtab;
sd->symbol_names_size = strtabshdr.get_sh_size();
}
// Return the section index of symbol SYM. Set *VALUE to its value in
// the object file. Note that for a symbol which is not defined in
// this object file, this will set *VALUE to 0 and return SHN_UNDEF;
// it will not return the final value of the symbol in the link.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::symbol_section_and_value(unsigned int sym,
Address* value)
{
off_t symbols_size;
const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
&symbols_size,
false);
const size_t count = symbols_size / This::sym_size;
gold_assert(sym < count);
elfcpp::Sym<size, big_endian> elfsym(symbols + sym * This::sym_size);
*value = elfsym.get_st_value();
// FIXME: Handle SHN_XINDEX.
return elfsym.get_st_shndx();
}
// Return whether to include a section group in the link. LAYOUT is
// used to keep track of which section groups we have already seen.
// INDEX is the index of the section group and SHDR is the section
// header. If we do not want to include this group, we set bits in
// OMIT for each section which should be discarded.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::include_section_group(
Layout* layout,
unsigned int index,
const elfcpp::Shdr<size, big_endian>& shdr,
std::vector<bool>* omit)
{
// Read the section contents.
const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
shdr.get_sh_size(), false);
const elfcpp::Elf_Word* pword =
reinterpret_cast<const elfcpp::Elf_Word*>(pcon);
// The first word contains flags. We only care about COMDAT section
// groups. Other section groups are always included in the link
// just like ordinary sections.
elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword);
if ((flags & elfcpp::GRP_COMDAT) == 0)
return true;
// Look up the group signature, which is the name of a symbol. This
// is a lot of effort to go to to read a string. Why didn't they
// just use the name of the SHT_GROUP section as the group
// signature?
// Get the appropriate symbol table header (this will normally be
// the single SHT_SYMTAB section, but in principle it need not be).
const unsigned int link = shdr.get_sh_link();
typename This::Shdr symshdr(this, this->elf_file_.section_header(link));
// Read the symbol table entry.
if (shdr.get_sh_info() >= symshdr.get_sh_size() / This::sym_size)
{
this->error(_("section group %u info %u out of range"),
index, shdr.get_sh_info());
return false;
}
off_t symoff = symshdr.get_sh_offset() + shdr.get_sh_info() * This::sym_size;
const unsigned char* psym = this->get_view(symoff, This::sym_size, true);
elfcpp::Sym<size, big_endian> sym(psym);
// Read the symbol table names.
off_t symnamelen;
const unsigned char* psymnamesu;
psymnamesu = this->section_contents(symshdr.get_sh_link(), &symnamelen,
true);
const char* psymnames = reinterpret_cast<const char*>(psymnamesu);
// Get the section group signature.
if (sym.get_st_name() >= symnamelen)
{
this->error(_("symbol %u name offset %u out of range"),
shdr.get_sh_info(), sym.get_st_name());
return false;
}
const char* signature = psymnames + sym.get_st_name();
// It seems that some versions of gas will create a section group
// associated with a section symbol, and then fail to give a name to
// the section symbol. In such a case, use the name of the section.
// FIXME.
std::string secname;
if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
{
secname = this->section_name(sym.get_st_shndx());
signature = secname.c_str();
}
// Record this section group, and see whether we've already seen one
// with the same signature.
if (layout->add_comdat(signature, true))
return true;
// This is a duplicate. We want to discard the sections in this
// group.
size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
for (size_t i = 1; i < count; ++i)
{
elfcpp::Elf_Word secnum =
elfcpp::Swap<32, big_endian>::readval(pword + i);
if (secnum >= this->shnum())
{
this->error(_("section %u in section group %u out of range"),
secnum, index);
continue;
}
(*omit)[secnum] = true;
}
return false;
}
// Whether to include a linkonce section in the link. NAME is the
// name of the section and SHDR is the section header.
// Linkonce sections are a GNU extension implemented in the original
// GNU linker before section groups were defined. The semantics are
// that we only include one linkonce section with a given name. The
// name of a linkonce section is normally .gnu.linkonce.T.SYMNAME,
// where T is the type of section and SYMNAME is the name of a symbol.
// In an attempt to make linkonce sections interact well with section
// groups, we try to identify SYMNAME and use it like a section group
// signature. We want to block section groups with that signature,
// but not other linkonce sections with that signature. We also use
// the full name of the linkonce section as a normal section group
// signature.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::include_linkonce_section(
Layout* layout,
const char* name,
const elfcpp::Shdr<size, big_endian>&)
{
// In general the symbol name we want will be the string following
// the last '.'. However, we have to handle the case of
// .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
// some versions of gcc. So we use a heuristic: if the name starts
// with ".gnu.linkonce.t.", we use everything after that. Otherwise
// we look for the last '.'. We can't always simply skip
// ".gnu.linkonce.X", because we have to deal with cases like
// ".gnu.linkonce.d.rel.ro.local".
const char* const linkonce_t = ".gnu.linkonce.t.";
const char* symname;
if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0)
symname = name + strlen(linkonce_t);
else
symname = strrchr(name, '.') + 1;
bool include1 = layout->add_comdat(symname, false);
bool include2 = layout->add_comdat(name, true);
return include1 && include2;
}
// Lay out the input sections. We walk through the sections and check
// whether they should be included in the link. If they should, we
// pass them to the Layout object, which will return an output section
// and an offset.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
Layout* layout,
Read_symbols_data* sd)
{
const unsigned int shnum = this->shnum();
if (shnum == 0)
return;
// Get the section headers.
const unsigned char* pshdrs = sd->section_headers->data();
// Get the section names.
const unsigned char* pnamesu = sd->section_names->data();
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// For each section, record the index of the reloc section if any.
// Use 0 to mean that there is no reloc section, -1U to mean that
// there is more than one.
std::vector<unsigned int> reloc_shndx(shnum, 0);
std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
// Skip the first, dummy, section.
pshdrs += This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
unsigned int sh_type = shdr.get_sh_type();
if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
{
unsigned int target_shndx = shdr.get_sh_info();
if (target_shndx == 0 || target_shndx >= shnum)
{
this->error(_("relocation section %u has bad info %u"),
i, target_shndx);
continue;
}
if (reloc_shndx[target_shndx] != 0)
reloc_shndx[target_shndx] = -1U;
else
{
reloc_shndx[target_shndx] = i;
reloc_type[target_shndx] = sh_type;
}
}
}
std::vector<Map_to_output>& map_sections(this->map_to_output());
map_sections.resize(shnum);
// Whether we've seen a .note.GNU-stack section.
bool seen_gnu_stack = false;
// The flags of a .note.GNU-stack section.
uint64_t gnu_stack_flags = 0;
// Keep track of which sections to omit.
std::vector<bool> omit(shnum, false);
// Keep track of .eh_frame sections.
std::vector<unsigned int> eh_frame_sections;
// Skip the first, dummy, section.
pshdrs = sd->section_headers->data() + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
if (shdr.get_sh_name() >= sd->section_names_size)
{
this->error(_("bad section name offset for section %u: %lu"),
i, static_cast<unsigned long>(shdr.get_sh_name()));
return;
}
const char* name = pnames + shdr.get_sh_name();
if (this->handle_gnu_warning_section(name, i, symtab))
{
if (!parameters->output_is_object())
omit[i] = true;
}
// The .note.GNU-stack section is special. It gives the
// protection flags that this object file requires for the stack
// in memory.
if (strcmp(name, ".note.GNU-stack") == 0)
{
seen_gnu_stack = true;
gnu_stack_flags |= shdr.get_sh_flags();
omit[i] = true;
}
bool discard = omit[i];
if (!discard)
{
if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
{
if (!this->include_section_group(layout, i, shdr, &omit))
discard = true;
}
else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
&& Layout::is_linkonce(name))
{
if (!this->include_linkonce_section(layout, name, shdr))
discard = true;
}
}
if (discard)
{
// Do not include this section in the link.
map_sections[i].output_section = NULL;
continue;
}
// The .eh_frame section is special. It holds exception frame
// information that we need to read in order to generate the
// exception frame header. We process these after all the other
// sections so that the exception frame reader can reliably
// determine which sections are being discarded, and discard the
// corresponding information.
if (!parameters->output_is_object()
&& strcmp(name, ".eh_frame") == 0
&& this->check_eh_frame_flags(&shdr))
{
eh_frame_sections.push_back(i);
continue;
}
off_t offset;
Output_section* os = layout->layout(this, i, name, shdr,
reloc_shndx[i], reloc_type[i],
&offset);
map_sections[i].output_section = os;
map_sections[i].offset = offset;
// If this section requires special handling, and if there are
// relocs that apply to it, then we must do the special handling
// before we apply the relocs.
if (offset == -1 && reloc_shndx[i] != 0)
this->set_relocs_must_follow_section_writes();
}
layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
// Handle the .eh_frame sections at the end.
for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
p != eh_frame_sections.end();
++p)
{
gold_assert(this->has_eh_frame_);
gold_assert(sd->external_symbols_offset != 0);
unsigned int i = *p;
const unsigned char *pshdr;
pshdr = sd->section_headers->data() + i * This::shdr_size;
typename This::Shdr shdr(pshdr);
off_t offset;
Output_section* os = layout->layout_eh_frame(this,
sd->symbols->data(),
sd->symbols_size,
sd->symbol_names->data(),
sd->symbol_names_size,
i, shdr,
reloc_shndx[i],
reloc_type[i],
&offset);
map_sections[i].output_section = os;
map_sections[i].offset = offset;
// If this section requires special handling, and if there are
// relocs that apply to it, then we must do the special handling
// before we apply the relocs.
if (offset == -1 && reloc_shndx[i] != 0)
this->set_relocs_must_follow_section_writes();
}
delete sd->section_headers;
sd->section_headers = NULL;
delete sd->section_names;
sd->section_names = NULL;
}
// Add the symbols to the symbol table.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
Read_symbols_data* sd)
{
if (sd->symbols == NULL)
{
gold_assert(sd->symbol_names == NULL);
return;
}
const int sym_size = This::sym_size;
size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
/ sym_size);
if (static_cast<off_t>(symcount * sym_size)
!= sd->symbols_size - sd->external_symbols_offset)
{
this->error(_("size of symbols is not multiple of symbol size"));
return;
}
this->symbols_.resize(symcount);
const char* sym_names =
reinterpret_cast<const char*>(sd->symbol_names->data());
symtab->add_from_relobj(this,
sd->symbols->data() + sd->external_symbols_offset,
symcount, sym_names, sd->symbol_names_size,
&this->symbols_);
delete sd->symbols;
sd->symbols = NULL;
delete sd->symbol_names;
sd->symbol_names = NULL;
}
// Finalize the local symbols. Here we add their names to *POOL and
// *DYNPOOL, and we add their values to THIS->LOCAL_VALUES_.
// This function is always called from the main thread. The actual
// output of the local symbols will occur in a separate task.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
Stringpool* dynpool)
{
gold_assert(this->symtab_shndx_ != -1U);
if (this->symtab_shndx_ == 0)
{
// This object has no symbols. Weird but legal.
return;
}
// Read the symbol table section header.
const unsigned int symtab_shndx = this->symtab_shndx_;
typename This::Shdr symtabshdr(this,
this->elf_file_.section_header(symtab_shndx));
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
// Read the local symbols.
const int sym_size = This::sym_size;
const unsigned int loccount = this->local_symbol_count_;
gold_assert(loccount == symtabshdr.get_sh_info());
off_t locsize = loccount * sym_size;
const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
locsize, true);
// Read the symbol names.
const unsigned int strtab_shndx = symtabshdr.get_sh_link();
off_t strtab_size;
const unsigned char* pnamesu = this->section_contents(strtab_shndx,
&strtab_size,
true);
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// Loop over the local symbols.
const std::vector<Map_to_output>& mo(this->map_to_output());
unsigned int shnum = this->shnum();
unsigned int count = 0;
unsigned int dyncount = 0;
// Skip the first, dummy, symbol.
psyms += sym_size;
for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
{
elfcpp::Sym<size, big_endian> sym(psyms);
Symbol_value<size>& lv(this->local_values_[i]);
unsigned int shndx = sym.get_st_shndx();
lv.set_input_shndx(shndx);
if (sym.get_st_type() == elfcpp::STT_SECTION)
lv.set_is_section_symbol();
else if (sym.get_st_type() == elfcpp::STT_TLS)
lv.set_is_tls_symbol();
// Save the input symbol value for use in do_finalize_local_symbols().
lv.set_input_value(sym.get_st_value());
// Decide whether this symbol should go into the output file.
if (shndx < shnum && mo[shndx].output_section == NULL)
{
lv.set_no_output_symtab_entry();
continue;
}
if (sym.get_st_type() == elfcpp::STT_SECTION)
{
lv.set_no_output_symtab_entry();
continue;
}
if (sym.get_st_name() >= strtab_size)
{
this->error(_("local symbol %u section name out of range: %u >= %u"),
i, sym.get_st_name(),
static_cast<unsigned int>(strtab_size));
lv.set_no_output_symtab_entry();
continue;
}
// Add the symbol to the symbol table string pool.
const char* name = pnames + sym.get_st_name();
pool->add(name, true, NULL);
++count;
// If needed, add the symbol to the dynamic symbol table string pool.
if (lv.needs_output_dynsym_entry())
{
dynpool->add(name, true, NULL);
++dyncount;
}
}
this->output_local_symbol_count_ = count;
this->output_local_dynsym_count_ = dyncount;
}
// Finalize the local symbols. Here we add their values to
// THIS->LOCAL_VALUES_ and set their output symbol table indexes.
// This function is always called from the main thread. The actual
// output of the local symbols will occur in a separate task.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
off_t off)
{
gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
const unsigned int loccount = this->local_symbol_count_;
this->local_symbol_offset_ = off;
const std::vector<Map_to_output>& mo(this->map_to_output());
unsigned int shnum = this->shnum();
for (unsigned int i = 1; i < loccount; ++i)
{
Symbol_value<size>& lv(this->local_values_[i]);
unsigned int shndx = lv.input_shndx();
// Set the output symbol value.
if (shndx >= elfcpp::SHN_LORESERVE)
{
if (shndx == elfcpp::SHN_ABS)
lv.set_output_value(lv.input_value());
else
{
// FIXME: Handle SHN_XINDEX.
this->error(_("unknown section index %u for local symbol %u"),
shndx, i);
lv.set_output_value(0);
}
}
else
{
if (shndx >= shnum)
{
this->error(_("local symbol %u section index %u out of range"),
i, shndx);
shndx = 0;
}
Output_section* os = mo[shndx].output_section;
if (os == NULL)
{
lv.set_output_value(0);
continue;
}
else if (mo[shndx].offset == -1)
{
// Leave the input value in place for SHF_MERGE sections.
}
else if (lv.is_tls_symbol())
lv.set_output_value(mo[shndx].output_section->tls_offset()
+ mo[shndx].offset
+ lv.input_value());
else
lv.set_output_value(mo[shndx].output_section->address()
+ mo[shndx].offset
+ lv.input_value());
}
if (lv.needs_output_symtab_entry())
{
lv.set_output_symtab_index(index);
++index;
}
}
return index;
}
// Set the output dynamic symbol table indexes for the local variables.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_set_local_dynsym_indexes(unsigned int index)
{
const unsigned int loccount = this->local_symbol_count_;
for (unsigned int i = 1; i < loccount; ++i)
{
Symbol_value<size>& lv(this->local_values_[i]);
if (lv.needs_output_dynsym_entry())
{
lv.set_output_dynsym_index(index);
++index;
}
}
return index;
}
// Set the offset where local dynamic symbol information will be stored.
// Returns the count of local symbols contributed to the symbol table by
// this object.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_set_local_dynsym_offset(off_t off)
{
gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
this->local_dynsym_offset_ = off;
return this->output_local_dynsym_count_;
}
// Return the value of the local symbol symndx.
template<int size, bool big_endian>
typename elfcpp::Elf_types<size>::Elf_Addr
Sized_relobj<size, big_endian>::local_symbol_value(unsigned int symndx) const
{
gold_assert(symndx < this->local_symbol_count_);
gold_assert(symndx < this->local_values_.size());
const Symbol_value<size>& lv(this->local_values_[symndx]);
return lv.value(this, 0);
}
// Return the value of a local symbol defined in input section SHNDX,
// with value VALUE, adding addend ADDEND. IS_SECTION_SYMBOL
// indicates whether the symbol is a section symbol. This handles
// SHF_MERGE sections.
template<int size, bool big_endian>
typename elfcpp::Elf_types<size>::Elf_Addr
Sized_relobj<size, big_endian>::local_value(unsigned int shndx,
Address value,
bool is_section_symbol,
Address addend) const
{
const std::vector<Map_to_output>& mo(this->map_to_output());
Output_section* os = mo[shndx].output_section;
if (os == NULL)
return addend;
gold_assert(mo[shndx].offset == -1);
// Do the mapping required by the output section. If this is not a
// section symbol, then we want to map the symbol value, and then
// include the addend. If this is a section symbol, then we need to
// include the addend to figure out where in the section we are,
// before we do the mapping. This will do the right thing provided
// the assembler is careful to only convert a relocation in a merged
// section to a section symbol if there is a zero addend. If the
// assembler does not do this, then in general we can't know what to
// do, because we can't distinguish the addend for the instruction
// format from the addend for the section offset.
if (is_section_symbol)
return os->output_address(this, shndx, value + addend);
else
return addend + os->output_address(this, shndx, value);
}
// Write out the local symbols.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::write_local_symbols(Output_file* of,
const Stringpool* sympool,
const Stringpool* dynpool)
{
if (parameters->strip_all() && this->output_local_dynsym_count_ == 0)
return;
gold_assert(this->symtab_shndx_ != -1U);
if (this->symtab_shndx_ == 0)
{
// This object has no symbols. Weird but legal.
return;
}
// Read the symbol table section header.
const unsigned int symtab_shndx = this->symtab_shndx_;
typename This::Shdr symtabshdr(this,
this->elf_file_.section_header(symtab_shndx));
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
const unsigned int loccount = this->local_symbol_count_;
gold_assert(loccount == symtabshdr.get_sh_info());
// Read the local symbols.
const int sym_size = This::sym_size;
off_t locsize = loccount * sym_size;
const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
locsize, false);
// Read the symbol names.
const unsigned int strtab_shndx = symtabshdr.get_sh_link();
off_t strtab_size;
const unsigned char* pnamesu = this->section_contents(strtab_shndx,
&strtab_size,
true);
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// Get views into the output file for the portions of the symbol table
// and the dynamic symbol table that we will be writing.
off_t output_size = this->output_local_symbol_count_ * sym_size;
unsigned char* oview = NULL;
if (output_size > 0)
oview = of->get_output_view(this->local_symbol_offset_, output_size);
off_t dyn_output_size = this->output_local_dynsym_count_ * sym_size;
unsigned char* dyn_oview = NULL;
if (dyn_output_size > 0)
dyn_oview = of->get_output_view(this->local_dynsym_offset_,
dyn_output_size);
const std::vector<Map_to_output>& mo(this->map_to_output());
gold_assert(this->local_values_.size() == loccount);
unsigned char* ov = oview;
unsigned char* dyn_ov = dyn_oview;
psyms += sym_size;
for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
{
elfcpp::Sym<size, big_endian> isym(psyms);
unsigned int st_shndx = isym.get_st_shndx();
if (st_shndx < elfcpp::SHN_LORESERVE)
{
gold_assert(st_shndx < mo.size());
if (mo[st_shndx].output_section == NULL)
continue;
st_shndx = mo[st_shndx].output_section->out_shndx();
}
// Write the symbol to the output symbol table.
if (!parameters->strip_all()
&& this->local_values_[i].needs_output_symtab_entry())
{
elfcpp::Sym_write<size, big_endian> osym(ov);
gold_assert(isym.get_st_name() < strtab_size);
const char* name = pnames + isym.get_st_name();
osym.put_st_name(sympool->get_offset(name));
osym.put_st_value(this->local_values_[i].value(this, 0));
osym.put_st_size(isym.get_st_size());
osym.put_st_info(isym.get_st_info());
osym.put_st_other(isym.get_st_other());
osym.put_st_shndx(st_shndx);
ov += sym_size;
}
// Write the symbol to the output dynamic symbol table.
if (this->local_values_[i].needs_output_dynsym_entry())
{
gold_assert(dyn_ov < dyn_oview + dyn_output_size);
elfcpp::Sym_write<size, big_endian> osym(dyn_ov);
gold_assert(isym.get_st_name() < strtab_size);
const char* name = pnames + isym.get_st_name();
osym.put_st_name(dynpool->get_offset(name));
osym.put_st_value(this->local_values_[i].value(this, 0));
osym.put_st_size(isym.get_st_size());
osym.put_st_info(isym.get_st_info());
osym.put_st_other(isym.get_st_other());
osym.put_st_shndx(st_shndx);
dyn_ov += sym_size;
}
}
if (output_size > 0)
{
gold_assert(ov - oview == output_size);
of->write_output_view(this->local_symbol_offset_, output_size, oview);
}
if (dyn_output_size > 0)
{
gold_assert(dyn_ov - dyn_oview == dyn_output_size);
of->write_output_view(this->local_dynsym_offset_, dyn_output_size,
dyn_oview);
}
}
// Set *INFO to symbolic information about the offset OFFSET in the
// section SHNDX. Return true if we found something, false if we
// found nothing.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::get_symbol_location_info(
unsigned int shndx,
off_t offset,
Symbol_location_info* info)
{
if (this->symtab_shndx_ == 0)
return false;
off_t symbols_size;
const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
&symbols_size,
false);
unsigned int symbol_names_shndx = this->section_link(this->symtab_shndx_);
off_t names_size;
const unsigned char* symbol_names_u =
this->section_contents(symbol_names_shndx, &names_size, false);
const char* symbol_names = reinterpret_cast<const char*>(symbol_names_u);
const int sym_size = This::sym_size;
const size_t count = symbols_size / sym_size;
const unsigned char* p = symbols;
for (size_t i = 0; i < count; ++i, p += sym_size)
{
elfcpp::Sym<size, big_endian> sym(p);
if (sym.get_st_type() == elfcpp::STT_FILE)
{
if (sym.get_st_name() >= names_size)
info->source_file = "(invalid)";
else
info->source_file = symbol_names + sym.get_st_name();
}
else if (sym.get_st_shndx() == shndx
&& static_cast<off_t>(sym.get_st_value()) <= offset
&& (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
> offset))
{
if (sym.get_st_name() > names_size)
info->enclosing_symbol_name = "(invalid)";
else
{
info->enclosing_symbol_name = symbol_names + sym.get_st_name();
if (parameters->demangle())
{
char* demangled_name = cplus_demangle(
info->enclosing_symbol_name.c_str(),
DMGL_ANSI | DMGL_PARAMS);
if (demangled_name != NULL)
{
info->enclosing_symbol_name.assign(demangled_name);
free(demangled_name);
}
}
}
return true;
}
}
return false;
}
// Input_objects methods.
// Add a regular relocatable object to the list. Return false if this
// object should be ignored.
bool
Input_objects::add_object(Object* obj)
{
Target* target = obj->target();
if (this->target_ == NULL)
this->target_ = target;
else if (this->target_ != target)
{
gold_error(_("%s: incompatible target"), obj->name().c_str());
return false;
}
if (!obj->is_dynamic())
this->relobj_list_.push_back(static_cast<Relobj*>(obj));
else
{
// See if this is a duplicate SONAME.
Dynobj* dynobj = static_cast<Dynobj*>(obj);
const char* soname = dynobj->soname();
std::pair<Unordered_set<std::string>::iterator, bool> ins =
this->sonames_.insert(soname);
if (!ins.second)
{
// We have already seen a dynamic object with this soname.
return false;
}
this->dynobj_list_.push_back(dynobj);
// If this is -lc, remember the directory in which we found it.
// We use this when issuing warnings about undefined symbols: as
// a heuristic, we don't warn about system libraries found in
// the same directory as -lc.
if (strncmp(soname, "libc.so", 7) == 0)
{
const char* object_name = dynobj->name().c_str();
const char* base = lbasename(object_name);
if (base != object_name)
this->system_library_directory_.assign(object_name,
base - 1 - object_name);
}
}
set_parameters_target(target);
return true;
}
// Return whether an object was found in the system library directory.
bool
Input_objects::found_in_system_library_directory(const Object* object) const
{
return (!this->system_library_directory_.empty()
&& object->name().compare(0,
this->system_library_directory_.size(),
this->system_library_directory_) == 0);
}
// For each dynamic object, record whether we've seen all of its
// explicit dependencies.
void
Input_objects::check_dynamic_dependencies() const
{
for (Dynobj_list::const_iterator p = this->dynobj_list_.begin();
p != this->dynobj_list_.end();
++p)
{
const Dynobj::Needed& needed((*p)->needed());
bool found_all = true;
for (Dynobj::Needed::const_iterator pneeded = needed.begin();
pneeded != needed.end();
++pneeded)
{
if (this->sonames_.find(*pneeded) == this->sonames_.end())
{
found_all = false;
break;
}
}
(*p)->set_has_unknown_needed_entries(!found_all);
}
}
// Relocate_info methods.
// Return a string describing the location of a relocation. This is
// only used in error messages.
template<int size, bool big_endian>
std::string
Relocate_info<size, big_endian>::location(size_t, off_t offset) const
{
// See if we can get line-number information from debugging sections.
std::string filename;
std::string file_and_lineno; // Better than filename-only, if available.
Sized_dwarf_line_info<size, big_endian> line_info(this->object);
// This will be "" if we failed to parse the debug info for any reason.
file_and_lineno = line_info.addr2line(this->data_shndx, offset);
std::string ret(this->object->name());
ret += ':';
Symbol_location_info info;
if (this->object->get_symbol_location_info(this->data_shndx, offset, &info))
{
ret += " in function ";
ret += info.enclosing_symbol_name;
ret += ":";
filename = info.source_file;
}
if (!file_and_lineno.empty())
ret += file_and_lineno;
else
{
if (!filename.empty())
ret += filename;
ret += "(";
ret += this->object->section_name(this->data_shndx);
char buf[100];
// Offsets into sections have to be positive.
snprintf(buf, sizeof(buf), "+0x%lx", static_cast<long>(offset));
ret += buf;
ret += ")";
}
return ret;
}
} // End namespace gold.
namespace
{
using namespace gold;
// Read an ELF file with the header and return the appropriate
// instance of Object.
template<int size, bool big_endian>
Object*
make_elf_sized_object(const std::string& name, Input_file* input_file,
off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
{
int et = ehdr.get_e_type();
if (et == elfcpp::ET_REL)
{
Sized_relobj<size, big_endian>* obj =
new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr);
obj->setup(ehdr);
return obj;
}
else if (et == elfcpp::ET_DYN)
{
Sized_dynobj<size, big_endian>* obj =
new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
obj->setup(ehdr);
return obj;
}
else
{
gold_error(_("%s: unsupported ELF file type %d"),
name.c_str(), et);
return NULL;
}
}
} // End anonymous namespace.
namespace gold
{
// Read an ELF file and return the appropriate instance of Object.
Object*
make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
const unsigned char* p, off_t bytes)
{
if (bytes < elfcpp::EI_NIDENT)
{
gold_error(_("%s: ELF file too short"), name.c_str());
return NULL;
}
int v = p[elfcpp::EI_VERSION];
if (v != elfcpp::EV_CURRENT)
{
if (v == elfcpp::EV_NONE)
gold_error(_("%s: invalid ELF version 0"), name.c_str());
else
gold_error(_("%s: unsupported ELF version %d"), name.c_str(), v);
return NULL;
}
int c = p[elfcpp::EI_CLASS];
if (c == elfcpp::ELFCLASSNONE)
{
gold_error(_("%s: invalid ELF class 0"), name.c_str());
return NULL;
}
else if (c != elfcpp::ELFCLASS32
&& c != elfcpp::ELFCLASS64)
{
gold_error(_("%s: unsupported ELF class %d"), name.c_str(), c);
return NULL;
}
int d = p[elfcpp::EI_DATA];
if (d == elfcpp::ELFDATANONE)
{
gold_error(_("%s: invalid ELF data encoding"), name.c_str());
return NULL;
}
else if (d != elfcpp::ELFDATA2LSB
&& d != elfcpp::ELFDATA2MSB)
{
gold_error(_("%s: unsupported ELF data encoding %d"), name.c_str(), d);
return NULL;
}
bool big_endian = d == elfcpp::ELFDATA2MSB;
if (c == elfcpp::ELFCLASS32)
{
if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
{
gold_error(_("%s: ELF file too short"), name.c_str());
return NULL;
}
if (big_endian)
{
#ifdef HAVE_TARGET_32_BIG
elfcpp::Ehdr<32, true> ehdr(p);
return make_elf_sized_object<32, true>(name, input_file,
offset, ehdr);
#else
gold_error(_("%s: not configured to support "
"32-bit big-endian object"),
name.c_str());
return NULL;
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
elfcpp::Ehdr<32, false> ehdr(p);
return make_elf_sized_object<32, false>(name, input_file,
offset, ehdr);
#else
gold_error(_("%s: not configured to support "
"32-bit little-endian object"),
name.c_str());
return NULL;
#endif
}
}
else
{
if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
{
gold_error(_("%s: ELF file too short"), name.c_str());
return NULL;
}
if (big_endian)
{
#ifdef HAVE_TARGET_64_BIG
elfcpp::Ehdr<64, true> ehdr(p);
return make_elf_sized_object<64, true>(name, input_file,
offset, ehdr);
#else
gold_error(_("%s: not configured to support "
"64-bit big-endian object"),
name.c_str());
return NULL;
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
elfcpp::Ehdr<64, false> ehdr(p);
return make_elf_sized_object<64, false>(name, input_file,
offset, ehdr);
#else
gold_error(_("%s: not configured to support "
"64-bit little-endian object"),
name.c_str());
return NULL;
#endif
}
}
}
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones for implemented targets.
#ifdef HAVE_TARGET_32_LITTLE
template
class Sized_relobj<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Sized_relobj<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Sized_relobj<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Sized_relobj<64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
struct Relocate_info<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
struct Relocate_info<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
struct Relocate_info<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
struct Relocate_info<64, true>;
#endif
} // End namespace gold.
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