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binutils-gdb/gold/output.cc
Ian Lance Taylor 4e9d858638 From Craig Silverstein: delete the output file first if it exists and 
is non-empty.
2007-10-10 06:29:10 +00:00

1898 lines
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// output.cc -- manage the output file for 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 <cstdlib>
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <algorithm>
#include "parameters.h"
#include "object.h"
#include "symtab.h"
#include "reloc.h"
#include "merge.h"
#include "output.h"
namespace gold
{
// Output_data variables.
bool Output_data::sizes_are_fixed;
// Output_data methods.
Output_data::~Output_data()
{
}
// Set the address and offset.
void
Output_data::set_address(uint64_t addr, off_t off)
{
this->address_ = addr;
this->offset_ = off;
// Let the child class know.
this->do_set_address(addr, off);
}
// Return the default alignment for a size--32 or 64.
uint64_t
Output_data::default_alignment(int size)
{
if (size == 32)
return 4;
else if (size == 64)
return 8;
else
gold_unreachable();
}
// Output_section_header methods. This currently assumes that the
// segment and section lists are complete at construction time.
Output_section_headers::Output_section_headers(
const Layout* layout,
const Layout::Segment_list* segment_list,
const Layout::Section_list* unattached_section_list,
const Stringpool* secnamepool)
: layout_(layout),
segment_list_(segment_list),
unattached_section_list_(unattached_section_list),
secnamepool_(secnamepool)
{
// Count all the sections. Start with 1 for the null section.
off_t count = 1;
for (Layout::Segment_list::const_iterator p = segment_list->begin();
p != segment_list->end();
++p)
if ((*p)->type() == elfcpp::PT_LOAD)
count += (*p)->output_section_count();
count += unattached_section_list->size();
const int size = parameters->get_size();
int shdr_size;
if (size == 32)
shdr_size = elfcpp::Elf_sizes<32>::shdr_size;
else if (size == 64)
shdr_size = elfcpp::Elf_sizes<64>::shdr_size;
else
gold_unreachable();
this->set_data_size(count * shdr_size);
}
// Write out the section headers.
void
Output_section_headers::do_write(Output_file* of)
{
if (parameters->get_size() == 32)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
this->do_sized_write<32, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
this->do_sized_write<32, false>(of);
#else
gold_unreachable();
#endif
}
}
else if (parameters->get_size() == 64)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
this->do_sized_write<64, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
this->do_sized_write<64, false>(of);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
template<int size, bool big_endian>
void
Output_section_headers::do_sized_write(Output_file* of)
{
off_t all_shdrs_size = this->data_size();
unsigned char* view = of->get_output_view(this->offset(), all_shdrs_size);
const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
unsigned char* v = view;
{
typename elfcpp::Shdr_write<size, big_endian> oshdr(v);
oshdr.put_sh_name(0);
oshdr.put_sh_type(elfcpp::SHT_NULL);
oshdr.put_sh_flags(0);
oshdr.put_sh_addr(0);
oshdr.put_sh_offset(0);
oshdr.put_sh_size(0);
oshdr.put_sh_link(0);
oshdr.put_sh_info(0);
oshdr.put_sh_addralign(0);
oshdr.put_sh_entsize(0);
}
v += shdr_size;
unsigned shndx = 1;
for (Layout::Segment_list::const_iterator p = this->segment_list_->begin();
p != this->segment_list_->end();
++p)
v = (*p)->write_section_headers SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
this->layout_, this->secnamepool_, v, &shndx
SELECT_SIZE_ENDIAN(size, big_endian));
for (Layout::Section_list::const_iterator p =
this->unattached_section_list_->begin();
p != this->unattached_section_list_->end();
++p)
{
gold_assert(shndx == (*p)->out_shndx());
elfcpp::Shdr_write<size, big_endian> oshdr(v);
(*p)->write_header(this->layout_, this->secnamepool_, &oshdr);
v += shdr_size;
++shndx;
}
of->write_output_view(this->offset(), all_shdrs_size, view);
}
// Output_segment_header methods.
Output_segment_headers::Output_segment_headers(
const Layout::Segment_list& segment_list)
: segment_list_(segment_list)
{
const int size = parameters->get_size();
int phdr_size;
if (size == 32)
phdr_size = elfcpp::Elf_sizes<32>::phdr_size;
else if (size == 64)
phdr_size = elfcpp::Elf_sizes<64>::phdr_size;
else
gold_unreachable();
this->set_data_size(segment_list.size() * phdr_size);
}
void
Output_segment_headers::do_write(Output_file* of)
{
if (parameters->get_size() == 32)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
this->do_sized_write<32, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
this->do_sized_write<32, false>(of);
#else
gold_unreachable();
#endif
}
}
else if (parameters->get_size() == 64)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
this->do_sized_write<64, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
this->do_sized_write<64, false>(of);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
template<int size, bool big_endian>
void
Output_segment_headers::do_sized_write(Output_file* of)
{
const int phdr_size = elfcpp::Elf_sizes<size>::phdr_size;
off_t all_phdrs_size = this->segment_list_.size() * phdr_size;
unsigned char* view = of->get_output_view(this->offset(),
all_phdrs_size);
unsigned char* v = view;
for (Layout::Segment_list::const_iterator p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
{
elfcpp::Phdr_write<size, big_endian> ophdr(v);
(*p)->write_header(&ophdr);
v += phdr_size;
}
of->write_output_view(this->offset(), all_phdrs_size, view);
}
// Output_file_header methods.
Output_file_header::Output_file_header(const Target* target,
const Symbol_table* symtab,
const Output_segment_headers* osh)
: target_(target),
symtab_(symtab),
segment_header_(osh),
section_header_(NULL),
shstrtab_(NULL)
{
const int size = parameters->get_size();
int ehdr_size;
if (size == 32)
ehdr_size = elfcpp::Elf_sizes<32>::ehdr_size;
else if (size == 64)
ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
else
gold_unreachable();
this->set_data_size(ehdr_size);
}
// Set the section table information for a file header.
void
Output_file_header::set_section_info(const Output_section_headers* shdrs,
const Output_section* shstrtab)
{
this->section_header_ = shdrs;
this->shstrtab_ = shstrtab;
}
// Write out the file header.
void
Output_file_header::do_write(Output_file* of)
{
if (parameters->get_size() == 32)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
this->do_sized_write<32, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
this->do_sized_write<32, false>(of);
#else
gold_unreachable();
#endif
}
}
else if (parameters->get_size() == 64)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
this->do_sized_write<64, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
this->do_sized_write<64, false>(of);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
// Write out the file header with appropriate size and endianess.
template<int size, bool big_endian>
void
Output_file_header::do_sized_write(Output_file* of)
{
gold_assert(this->offset() == 0);
int ehdr_size = elfcpp::Elf_sizes<size>::ehdr_size;
unsigned char* view = of->get_output_view(0, ehdr_size);
elfcpp::Ehdr_write<size, big_endian> oehdr(view);
unsigned char e_ident[elfcpp::EI_NIDENT];
memset(e_ident, 0, elfcpp::EI_NIDENT);
e_ident[elfcpp::EI_MAG0] = elfcpp::ELFMAG0;
e_ident[elfcpp::EI_MAG1] = elfcpp::ELFMAG1;
e_ident[elfcpp::EI_MAG2] = elfcpp::ELFMAG2;
e_ident[elfcpp::EI_MAG3] = elfcpp::ELFMAG3;
if (size == 32)
e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS32;
else if (size == 64)
e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS64;
else
gold_unreachable();
e_ident[elfcpp::EI_DATA] = (big_endian
? elfcpp::ELFDATA2MSB
: elfcpp::ELFDATA2LSB);
e_ident[elfcpp::EI_VERSION] = elfcpp::EV_CURRENT;
// FIXME: Some targets may need to set EI_OSABI and EI_ABIVERSION.
oehdr.put_e_ident(e_ident);
elfcpp::ET e_type;
// FIXME: ET_DYN.
if (parameters->output_is_object())
e_type = elfcpp::ET_REL;
else
e_type = elfcpp::ET_EXEC;
oehdr.put_e_type(e_type);
oehdr.put_e_machine(this->target_->machine_code());
oehdr.put_e_version(elfcpp::EV_CURRENT);
// FIXME: Need to support -e, and target specific entry symbol.
Symbol* sym = this->symtab_->lookup("_start");
typename Sized_symbol<size>::Value_type v;
if (sym == NULL)
v = 0;
else
{
Sized_symbol<size>* ssym;
ssym = this->symtab_->get_sized_symbol SELECT_SIZE_NAME(size) (
sym SELECT_SIZE(size));
v = ssym->value();
}
oehdr.put_e_entry(v);
oehdr.put_e_phoff(this->segment_header_->offset());
oehdr.put_e_shoff(this->section_header_->offset());
// FIXME: The target needs to set the flags.
oehdr.put_e_flags(0);
oehdr.put_e_ehsize(elfcpp::Elf_sizes<size>::ehdr_size);
oehdr.put_e_phentsize(elfcpp::Elf_sizes<size>::phdr_size);
oehdr.put_e_phnum(this->segment_header_->data_size()
/ elfcpp::Elf_sizes<size>::phdr_size);
oehdr.put_e_shentsize(elfcpp::Elf_sizes<size>::shdr_size);
oehdr.put_e_shnum(this->section_header_->data_size()
/ elfcpp::Elf_sizes<size>::shdr_size);
oehdr.put_e_shstrndx(this->shstrtab_->out_shndx());
of->write_output_view(0, ehdr_size, view);
}
// Output_data_const methods.
void
Output_data_const::do_write(Output_file* of)
{
of->write(this->offset(), this->data_.data(), this->data_.size());
}
// Output_data_const_buffer methods.
void
Output_data_const_buffer::do_write(Output_file* of)
{
of->write(this->offset(), this->p_, this->data_size());
}
// Output_section_data methods.
// Record the output section, and set the entry size and such.
void
Output_section_data::set_output_section(Output_section* os)
{
gold_assert(this->output_section_ == NULL);
this->output_section_ = os;
this->do_adjust_output_section(os);
}
// Return the section index of the output section.
unsigned int
Output_section_data::do_out_shndx() const
{
gold_assert(this->output_section_ != NULL);
return this->output_section_->out_shndx();
}
// Output_data_strtab methods.
// Set the address. We don't actually care about the address, but we
// do set our final size.
void
Output_data_strtab::do_set_address(uint64_t, off_t)
{
this->strtab_->set_string_offsets();
this->set_data_size(this->strtab_->get_strtab_size());
}
// Write out a string table.
void
Output_data_strtab::do_write(Output_file* of)
{
this->strtab_->write(of, this->offset());
}
// Output_reloc methods.
// Get the symbol index of a relocation.
template<bool dynamic, int size, bool big_endian>
unsigned int
Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::get_symbol_index()
const
{
unsigned int index;
switch (this->local_sym_index_)
{
case INVALID_CODE:
gold_unreachable();
case GSYM_CODE:
if (this->u1_.gsym == NULL)
index = 0;
else if (dynamic)
index = this->u1_.gsym->dynsym_index();
else
index = this->u1_.gsym->symtab_index();
break;
case SECTION_CODE:
if (dynamic)
index = this->u1_.os->dynsym_index();
else
index = this->u1_.os->symtab_index();
break;
default:
if (dynamic)
{
// FIXME: It seems that some targets may need to generate
// dynamic relocations against local symbols for some
// reasons. This will have to be addressed at some point.
gold_unreachable();
}
else
index = this->u1_.relobj->symtab_index(this->local_sym_index_);
break;
}
gold_assert(index != -1U);
return index;
}
// Write out the offset and info fields of a Rel or Rela relocation
// entry.
template<bool dynamic, int size, bool big_endian>
template<typename Write_rel>
void
Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::write_rel(
Write_rel* wr) const
{
Address address = this->address_;
if (this->shndx_ != INVALID_CODE)
{
off_t off;
Output_section* os = this->u2_.relobj->output_section(this->shndx_,
&off);
gold_assert(os != NULL);
address += os->address() + off;
}
else if (this->u2_.od != NULL)
address += this->u2_.od->address();
wr->put_r_offset(address);
wr->put_r_info(elfcpp::elf_r_info<size>(this->get_symbol_index(),
this->type_));
}
// Write out a Rel relocation.
template<bool dynamic, int size, bool big_endian>
void
Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::write(
unsigned char* pov) const
{
elfcpp::Rel_write<size, big_endian> orel(pov);
this->write_rel(&orel);
}
// Write out a Rela relocation.
template<bool dynamic, int size, bool big_endian>
void
Output_reloc<elfcpp::SHT_RELA, dynamic, size, big_endian>::write(
unsigned char* pov) const
{
elfcpp::Rela_write<size, big_endian> orel(pov);
this->rel_.write_rel(&orel);
orel.put_r_addend(this->addend_);
}
// Output_data_reloc_base methods.
// Adjust the output section.
template<int sh_type, bool dynamic, int size, bool big_endian>
void
Output_data_reloc_base<sh_type, dynamic, size, big_endian>
::do_adjust_output_section(Output_section* os)
{
if (sh_type == elfcpp::SHT_REL)
os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
else if (sh_type == elfcpp::SHT_RELA)
os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
else
gold_unreachable();
if (dynamic)
os->set_should_link_to_dynsym();
else
os->set_should_link_to_symtab();
}
// Write out relocation data.
template<int sh_type, bool dynamic, int size, bool big_endian>
void
Output_data_reloc_base<sh_type, dynamic, size, big_endian>::do_write(
Output_file* of)
{
const off_t off = this->offset();
const off_t oview_size = this->data_size();
unsigned char* const oview = of->get_output_view(off, oview_size);
unsigned char* pov = oview;
for (typename Relocs::const_iterator p = this->relocs_.begin();
p != this->relocs_.end();
++p)
{
p->write(pov);
pov += reloc_size;
}
gold_assert(pov - oview == oview_size);
of->write_output_view(off, oview_size, oview);
// We no longer need the relocation entries.
this->relocs_.clear();
}
// Output_data_got::Got_entry methods.
// Write out the entry.
template<int size, bool big_endian>
void
Output_data_got<size, big_endian>::Got_entry::write(unsigned char* pov) const
{
Valtype val = 0;
switch (this->local_sym_index_)
{
case GSYM_CODE:
{
Symbol* gsym = this->u_.gsym;
// If the symbol is resolved locally, we need to write out its
// value. Otherwise we just write zero. The target code is
// responsible for creating a relocation entry to fill in the
// value at runtime.
if (gsym->final_value_is_known())
{
Sized_symbol<size>* sgsym;
// This cast is a bit ugly. We don't want to put a
// virtual method in Symbol, because we want Symbol to be
// as small as possible.
sgsym = static_cast<Sized_symbol<size>*>(gsym);
val = sgsym->value();
}
}
break;
case CONSTANT_CODE:
val = this->u_.constant;
break;
default:
val = this->u_.object->local_symbol_value(this->local_sym_index_);
break;
}
elfcpp::Swap<size, big_endian>::writeval(pov, val);
}
// Output_data_got methods.
// Add an entry for a global symbol to the GOT. This returns true if
// this is a new GOT entry, false if the symbol already had a GOT
// entry.
template<int size, bool big_endian>
bool
Output_data_got<size, big_endian>::add_global(Symbol* gsym)
{
if (gsym->has_got_offset())
return false;
this->entries_.push_back(Got_entry(gsym));
this->set_got_size();
gsym->set_got_offset(this->last_got_offset());
return true;
}
// Add an entry for a local symbol to the GOT. This returns true if
// this is a new GOT entry, false if the symbol already has a GOT
// entry.
template<int size, bool big_endian>
bool
Output_data_got<size, big_endian>::add_local(
Sized_relobj<size, big_endian>* object,
unsigned int symndx)
{
if (object->local_has_got_offset(symndx))
return false;
this->entries_.push_back(Got_entry(object, symndx));
this->set_got_size();
object->set_local_got_offset(symndx, this->last_got_offset());
return true;
}
// Write out the GOT.
template<int size, bool big_endian>
void
Output_data_got<size, big_endian>::do_write(Output_file* of)
{
const int add = size / 8;
const off_t off = this->offset();
const off_t oview_size = this->data_size();
unsigned char* const oview = of->get_output_view(off, oview_size);
unsigned char* pov = oview;
for (typename Got_entries::const_iterator p = this->entries_.begin();
p != this->entries_.end();
++p)
{
p->write(pov);
pov += add;
}
gold_assert(pov - oview == oview_size);
of->write_output_view(off, oview_size, oview);
// We no longer need the GOT entries.
this->entries_.clear();
}
// Output_data_dynamic::Dynamic_entry methods.
// Write out the entry.
template<int size, bool big_endian>
void
Output_data_dynamic::Dynamic_entry::write(
unsigned char* pov,
const Stringpool* pool
ACCEPT_SIZE_ENDIAN) const
{
typename elfcpp::Elf_types<size>::Elf_WXword val;
switch (this->classification_)
{
case DYNAMIC_NUMBER:
val = this->u_.val;
break;
case DYNAMIC_SECTION_ADDRESS:
val = this->u_.od->address();
break;
case DYNAMIC_SECTION_SIZE:
val = this->u_.od->data_size();
break;
case DYNAMIC_SYMBOL:
{
const Sized_symbol<size>* s =
static_cast<const Sized_symbol<size>*>(this->u_.sym);
val = s->value();
}
break;
case DYNAMIC_STRING:
val = pool->get_offset(this->u_.str);
break;
default:
gold_unreachable();
}
elfcpp::Dyn_write<size, big_endian> dw(pov);
dw.put_d_tag(this->tag_);
dw.put_d_val(val);
}
// Output_data_dynamic methods.
// Adjust the output section to set the entry size.
void
Output_data_dynamic::do_adjust_output_section(Output_section* os)
{
if (parameters->get_size() == 32)
os->set_entsize(elfcpp::Elf_sizes<32>::dyn_size);
else if (parameters->get_size() == 64)
os->set_entsize(elfcpp::Elf_sizes<64>::dyn_size);
else
gold_unreachable();
}
// Set the final data size.
void
Output_data_dynamic::do_set_address(uint64_t, off_t)
{
// Add the terminating entry.
this->add_constant(elfcpp::DT_NULL, 0);
int dyn_size;
if (parameters->get_size() == 32)
dyn_size = elfcpp::Elf_sizes<32>::dyn_size;
else if (parameters->get_size() == 64)
dyn_size = elfcpp::Elf_sizes<64>::dyn_size;
else
gold_unreachable();
this->set_data_size(this->entries_.size() * dyn_size);
}
// Write out the dynamic entries.
void
Output_data_dynamic::do_write(Output_file* of)
{
if (parameters->get_size() == 32)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
this->sized_write<32, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
this->sized_write<32, false>(of);
#else
gold_unreachable();
#endif
}
}
else if (parameters->get_size() == 64)
{
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
this->sized_write<64, true>(of);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
this->sized_write<64, false>(of);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
template<int size, bool big_endian>
void
Output_data_dynamic::sized_write(Output_file* of)
{
const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
const off_t offset = this->offset();
const off_t oview_size = this->data_size();
unsigned char* const oview = of->get_output_view(offset, oview_size);
unsigned char* pov = oview;
for (typename Dynamic_entries::const_iterator p = this->entries_.begin();
p != this->entries_.end();
++p)
{
p->write SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
pov, this->pool_ SELECT_SIZE_ENDIAN(size, big_endian));
pov += dyn_size;
}
gold_assert(pov - oview == oview_size);
of->write_output_view(offset, oview_size, oview);
// We no longer need the dynamic entries.
this->entries_.clear();
}
// Output_section::Input_section methods.
// Return the data size. For an input section we store the size here.
// For an Output_section_data, we have to ask it for the size.
off_t
Output_section::Input_section::data_size() const
{
if (this->is_input_section())
return this->u1_.data_size;
else
return this->u2_.posd->data_size();
}
// Set the address and file offset.
void
Output_section::Input_section::set_address(uint64_t addr, off_t off,
off_t secoff)
{
if (this->is_input_section())
this->u2_.object->set_section_offset(this->shndx_, off - secoff);
else
this->u2_.posd->set_address(addr, off);
}
// Try to turn an input address into an output address.
bool
Output_section::Input_section::output_address(const Relobj* object,
unsigned int shndx,
off_t offset,
uint64_t output_section_address,
uint64_t *poutput) const
{
if (!this->is_input_section())
return this->u2_.posd->output_address(object, shndx, offset,
output_section_address, poutput);
else
{
if (this->shndx_ != shndx
|| this->u2_.object != object)
return false;
off_t output_offset;
Output_section* os = object->output_section(shndx, &output_offset);
gold_assert(os != NULL);
*poutput = output_section_address + output_offset + offset;
return true;
}
}
// Write out the data. We don't have to do anything for an input
// section--they are handled via Object::relocate--but this is where
// we write out the data for an Output_section_data.
void
Output_section::Input_section::write(Output_file* of)
{
if (!this->is_input_section())
this->u2_.posd->write(of);
}
// Output_section methods.
// Construct an Output_section. NAME will point into a Stringpool.
Output_section::Output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags)
: name_(name),
addralign_(0),
entsize_(0),
link_section_(NULL),
link_(0),
info_section_(NULL),
info_(0),
type_(type),
flags_(flags),
out_shndx_(0),
symtab_index_(0),
dynsym_index_(0),
input_sections_(),
first_input_offset_(0),
fills_(),
needs_symtab_index_(false),
needs_dynsym_index_(false),
should_link_to_symtab_(false),
should_link_to_dynsym_(false)
{
}
Output_section::~Output_section()
{
}
// Set the entry size.
void
Output_section::set_entsize(uint64_t v)
{
if (this->entsize_ == 0)
this->entsize_ = v;
else
gold_assert(this->entsize_ == v);
}
// Add the input section SHNDX, with header SHDR, named SECNAME, in
// OBJECT, to the Output_section. Return the offset of the input
// section within the output section. We don't always keep track of
// input sections for an Output_section. Instead, each Object keeps
// track of the Output_section for each of its input sections.
template<int size, bool big_endian>
off_t
Output_section::add_input_section(Relobj* object, unsigned int shndx,
const char* secname,
const elfcpp::Shdr<size, big_endian>& shdr)
{
elfcpp::Elf_Xword addralign = shdr.get_sh_addralign();
if ((addralign & (addralign - 1)) != 0)
{
fprintf(stderr, _("%s: %s: invalid alignment %lu for section \"%s\"\n"),
program_name, object->name().c_str(),
static_cast<unsigned long>(addralign), secname);
gold_exit(false);
}
if (addralign > this->addralign_)
this->addralign_ = addralign;
// If this is a SHF_MERGE section, we pass all the input sections to
// a Output_data_merge.
if ((shdr.get_sh_flags() & elfcpp::SHF_MERGE) != 0)
{
if (this->add_merge_input_section(object, shndx, shdr.get_sh_flags(),
shdr.get_sh_entsize(),
addralign))
{
// Tell the relocation routines that they need to call the
// output_address method to determine the final address.
return -1;
}
}
off_t offset_in_section = this->data_size();
off_t aligned_offset_in_section = align_address(offset_in_section,
addralign);
if (aligned_offset_in_section > offset_in_section
&& (shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0
&& object->target()->has_code_fill())
{
// We need to add some fill data. Using fill_list_ when
// possible is an optimization, since we will often have fill
// sections without input sections.
off_t fill_len = aligned_offset_in_section - offset_in_section;
if (this->input_sections_.empty())
this->fills_.push_back(Fill(offset_in_section, fill_len));
else
{
// FIXME: When relaxing, the size needs to adjust to
// maintain a constant alignment.
std::string fill_data(object->target()->code_fill(fill_len));
Output_data_const* odc = new Output_data_const(fill_data, 1);
this->input_sections_.push_back(Input_section(odc));
}
}
this->set_data_size(aligned_offset_in_section + shdr.get_sh_size());
// We need to keep track of this section if we are already keeping
// track of sections, or if we are relaxing. FIXME: Add test for
// relaxing.
if (!this->input_sections_.empty())
this->input_sections_.push_back(Input_section(object, shndx,
shdr.get_sh_size(),
addralign));
return aligned_offset_in_section;
}
// Add arbitrary data to an output section.
void
Output_section::add_output_section_data(Output_section_data* posd)
{
Input_section inp(posd);
this->add_output_section_data(&inp);
}
// Add arbitrary data to an output section by Input_section.
void
Output_section::add_output_section_data(Input_section* inp)
{
if (this->input_sections_.empty())
this->first_input_offset_ = this->data_size();
this->input_sections_.push_back(*inp);
uint64_t addralign = inp->addralign();
if (addralign > this->addralign_)
this->addralign_ = addralign;
inp->set_output_section(this);
}
// Add a merge section to an output section.
void
Output_section::add_output_merge_section(Output_section_data* posd,
bool is_string, uint64_t entsize)
{
Input_section inp(posd, is_string, entsize);
this->add_output_section_data(&inp);
}
// Add an input section to a SHF_MERGE section.
bool
Output_section::add_merge_input_section(Relobj* object, unsigned int shndx,
uint64_t flags, uint64_t entsize,
uint64_t addralign)
{
// We only merge constants if the alignment is not more than the
// entry size. This could be handled, but it's unusual.
if (addralign > entsize)
return false;
bool is_string = (flags & elfcpp::SHF_STRINGS) != 0;
Input_section_list::iterator p;
for (p = this->input_sections_.begin();
p != this->input_sections_.end();
++p)
if (p->is_merge_section(is_string, entsize))
break;
// We handle the actual constant merging in Output_merge_data or
// Output_merge_string_data.
if (p != this->input_sections_.end())
p->add_input_section(object, shndx);
else
{
Output_section_data* posd;
if (!is_string)
posd = new Output_merge_data(entsize);
else if (entsize == 1)
posd = new Output_merge_string<char>();
else if (entsize == 2)
posd = new Output_merge_string<uint16_t>();
else if (entsize == 4)
posd = new Output_merge_string<uint32_t>();
else
return false;
this->add_output_merge_section(posd, is_string, entsize);
posd->add_input_section(object, shndx);
}
return true;
}
// Return the output virtual address of OFFSET relative to the start
// of input section SHNDX in object OBJECT.
uint64_t
Output_section::output_address(const Relobj* object, unsigned int shndx,
off_t offset) const
{
uint64_t addr = this->address() + this->first_input_offset_;
for (Input_section_list::const_iterator p = this->input_sections_.begin();
p != this->input_sections_.end();
++p)
{
addr = align_address(addr, p->addralign());
uint64_t output;
if (p->output_address(object, shndx, offset, addr, &output))
return output;
addr += p->data_size();
}
// If we get here, it means that we don't know the mapping for this
// input section. This might happen in principle if
// add_input_section were called before add_output_section_data.
// But it should never actually happen.
gold_unreachable();
}
// Set the address of an Output_section. This is where we handle
// setting the addresses of any Output_section_data objects.
void
Output_section::do_set_address(uint64_t address, off_t startoff)
{
if (this->input_sections_.empty())
return;
off_t off = startoff + this->first_input_offset_;
for (Input_section_list::iterator p = this->input_sections_.begin();
p != this->input_sections_.end();
++p)
{
off = align_address(off, p->addralign());
p->set_address(address + (off - startoff), off, startoff);
off += p->data_size();
}
this->set_data_size(off - startoff);
}
// Write the section header to *OSHDR.
template<int size, bool big_endian>
void
Output_section::write_header(const Layout* layout,
const Stringpool* secnamepool,
elfcpp::Shdr_write<size, big_endian>* oshdr) const
{
oshdr->put_sh_name(secnamepool->get_offset(this->name_));
oshdr->put_sh_type(this->type_);
oshdr->put_sh_flags(this->flags_);
oshdr->put_sh_addr(this->address());
oshdr->put_sh_offset(this->offset());
oshdr->put_sh_size(this->data_size());
if (this->link_section_ != NULL)
oshdr->put_sh_link(this->link_section_->out_shndx());
else if (this->should_link_to_symtab_)
oshdr->put_sh_link(layout->symtab_section()->out_shndx());
else if (this->should_link_to_dynsym_)
oshdr->put_sh_link(layout->dynsym_section()->out_shndx());
else
oshdr->put_sh_link(this->link_);
if (this->info_section_ != NULL)
oshdr->put_sh_info(this->info_section_->out_shndx());
else
oshdr->put_sh_info(this->info_);
oshdr->put_sh_addralign(this->addralign_);
oshdr->put_sh_entsize(this->entsize_);
}
// Write out the data. For input sections the data is written out by
// Object::relocate, but we have to handle Output_section_data objects
// here.
void
Output_section::do_write(Output_file* of)
{
off_t output_section_file_offset = this->offset();
for (Fill_list::iterator p = this->fills_.begin();
p != this->fills_.end();
++p)
{
std::string fill_data(of->target()->code_fill(p->length()));
of->write(output_section_file_offset + p->section_offset(),
fill_data.data(), fill_data.size());
}
for (Input_section_list::iterator p = this->input_sections_.begin();
p != this->input_sections_.end();
++p)
p->write(of);
}
// Output segment methods.
Output_segment::Output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
: output_data_(),
output_bss_(),
vaddr_(0),
paddr_(0),
memsz_(0),
align_(0),
offset_(0),
filesz_(0),
type_(type),
flags_(flags),
is_align_known_(false)
{
}
// Add an Output_section to an Output_segment.
void
Output_segment::add_output_section(Output_section* os,
elfcpp::Elf_Word seg_flags,
bool front)
{
gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
gold_assert(!this->is_align_known_);
// Update the segment flags.
this->flags_ |= seg_flags;
Output_segment::Output_data_list* pdl;
if (os->type() == elfcpp::SHT_NOBITS)
pdl = &this->output_bss_;
else
pdl = &this->output_data_;
// So that PT_NOTE segments will work correctly, we need to ensure
// that all SHT_NOTE sections are adjacent. This will normally
// happen automatically, because all the SHT_NOTE input sections
// will wind up in the same output section. However, it is possible
// for multiple SHT_NOTE input sections to have different section
// flags, and thus be in different output sections, but for the
// different section flags to map into the same segment flags and
// thus the same output segment.
// Note that while there may be many input sections in an output
// section, there are normally only a few output sections in an
// output segment. This loop is expected to be fast.
if (os->type() == elfcpp::SHT_NOTE && !pdl->empty())
{
Output_segment::Output_data_list::iterator p = pdl->end();
do
{
--p;
if ((*p)->is_section_type(elfcpp::SHT_NOTE))
{
// We don't worry about the FRONT parameter.
++p;
pdl->insert(p, os);
return;
}
}
while (p != pdl->begin());
}
// Similarly, so that PT_TLS segments will work, we need to group
// SHF_TLS sections. An SHF_TLS/SHT_NOBITS section is a special
// case: we group the SHF_TLS/SHT_NOBITS sections right after the
// SHF_TLS/SHT_PROGBITS sections. This lets us set up PT_TLS
// correctly.
if ((os->flags() & elfcpp::SHF_TLS) != 0 && !this->output_data_.empty())
{
pdl = &this->output_data_;
bool nobits = os->type() == elfcpp::SHT_NOBITS;
bool sawtls = false;
Output_segment::Output_data_list::iterator p = pdl->end();
do
{
--p;
bool insert;
if ((*p)->is_section_flag_set(elfcpp::SHF_TLS))
{
sawtls = true;
// Put a NOBITS section after the first TLS section.
// But a PROGBITS section after the first TLS/PROGBITS
// section.
insert = nobits || !(*p)->is_section_type(elfcpp::SHT_NOBITS);
}
else
{
// If we've gone past the TLS sections, but we've seen a
// TLS section, then we need to insert this section now.
insert = sawtls;
}
if (insert)
{
// We don't worry about the FRONT parameter.
++p;
pdl->insert(p, os);
return;
}
}
while (p != pdl->begin());
// There are no TLS sections yet; put this one at the requested
// location in the section list.
}
if (front)
pdl->push_front(os);
else
pdl->push_back(os);
}
// Add an Output_data (which is not an Output_section) to the start of
// a segment.
void
Output_segment::add_initial_output_data(Output_data* od)
{
gold_assert(!this->is_align_known_);
this->output_data_.push_front(od);
}
// Return the maximum alignment of the Output_data in Output_segment.
// Once we compute this, we prohibit new sections from being added.
uint64_t
Output_segment::addralign()
{
if (!this->is_align_known_)
{
uint64_t addralign;
addralign = Output_segment::maximum_alignment(&this->output_data_);
if (addralign > this->align_)
this->align_ = addralign;
addralign = Output_segment::maximum_alignment(&this->output_bss_);
if (addralign > this->align_)
this->align_ = addralign;
this->is_align_known_ = true;
}
return this->align_;
}
// Return the maximum alignment of a list of Output_data.
uint64_t
Output_segment::maximum_alignment(const Output_data_list* pdl)
{
uint64_t ret = 0;
for (Output_data_list::const_iterator p = pdl->begin();
p != pdl->end();
++p)
{
uint64_t addralign = (*p)->addralign();
if (addralign > ret)
ret = addralign;
}
return ret;
}
// Set the section addresses for an Output_segment. ADDR is the
// address and *POFF is the file offset. Set the section indexes
// starting with *PSHNDX. Return the address of the immediately
// following segment. Update *POFF and *PSHNDX.
uint64_t
Output_segment::set_section_addresses(uint64_t addr, off_t* poff,
unsigned int* pshndx)
{
gold_assert(this->type_ == elfcpp::PT_LOAD);
this->vaddr_ = addr;
this->paddr_ = addr;
off_t orig_off = *poff;
this->offset_ = orig_off;
*poff = align_address(*poff, this->addralign());
addr = this->set_section_list_addresses(&this->output_data_, addr, poff,
pshndx);
this->filesz_ = *poff - orig_off;
off_t off = *poff;
uint64_t ret = this->set_section_list_addresses(&this->output_bss_, addr,
poff, pshndx);
this->memsz_ = *poff - orig_off;
// Ignore the file offset adjustments made by the BSS Output_data
// objects.
*poff = off;
return ret;
}
// Set the addresses and file offsets in a list of Output_data
// structures.
uint64_t
Output_segment::set_section_list_addresses(Output_data_list* pdl,
uint64_t addr, off_t* poff,
unsigned int* pshndx)
{
off_t startoff = *poff;
off_t off = startoff;
for (Output_data_list::iterator p = pdl->begin();
p != pdl->end();
++p)
{
off = align_address(off, (*p)->addralign());
(*p)->set_address(addr + (off - startoff), off);
// Unless this is a PT_TLS segment, we want to ignore the size
// of a SHF_TLS/SHT_NOBITS section. Such a section does not
// affect the size of a PT_LOAD segment.
if (this->type_ == elfcpp::PT_TLS
|| !(*p)->is_section_flag_set(elfcpp::SHF_TLS)
|| !(*p)->is_section_type(elfcpp::SHT_NOBITS))
off += (*p)->data_size();
if ((*p)->is_section())
{
(*p)->set_out_shndx(*pshndx);
++*pshndx;
}
}
*poff = off;
return addr + (off - startoff);
}
// For a non-PT_LOAD segment, set the offset from the sections, if
// any.
void
Output_segment::set_offset()
{
gold_assert(this->type_ != elfcpp::PT_LOAD);
if (this->output_data_.empty() && this->output_bss_.empty())
{
this->vaddr_ = 0;
this->paddr_ = 0;
this->memsz_ = 0;
this->align_ = 0;
this->offset_ = 0;
this->filesz_ = 0;
return;
}
const Output_data* first;
if (this->output_data_.empty())
first = this->output_bss_.front();
else
first = this->output_data_.front();
this->vaddr_ = first->address();
this->paddr_ = this->vaddr_;
this->offset_ = first->offset();
if (this->output_data_.empty())
this->filesz_ = 0;
else
{
const Output_data* last_data = this->output_data_.back();
this->filesz_ = (last_data->address()
+ last_data->data_size()
- this->vaddr_);
}
const Output_data* last;
if (this->output_bss_.empty())
last = this->output_data_.back();
else
last = this->output_bss_.back();
this->memsz_ = (last->address()
+ last->data_size()
- this->vaddr_);
}
// Return the number of Output_sections in an Output_segment.
unsigned int
Output_segment::output_section_count() const
{
return (this->output_section_count_list(&this->output_data_)
+ this->output_section_count_list(&this->output_bss_));
}
// Return the number of Output_sections in an Output_data_list.
unsigned int
Output_segment::output_section_count_list(const Output_data_list* pdl) const
{
unsigned int count = 0;
for (Output_data_list::const_iterator p = pdl->begin();
p != pdl->end();
++p)
{
if ((*p)->is_section())
++count;
}
return count;
}
// Write the segment data into *OPHDR.
template<int size, bool big_endian>
void
Output_segment::write_header(elfcpp::Phdr_write<size, big_endian>* ophdr)
{
ophdr->put_p_type(this->type_);
ophdr->put_p_offset(this->offset_);
ophdr->put_p_vaddr(this->vaddr_);
ophdr->put_p_paddr(this->paddr_);
ophdr->put_p_filesz(this->filesz_);
ophdr->put_p_memsz(this->memsz_);
ophdr->put_p_flags(this->flags_);
ophdr->put_p_align(this->addralign());
}
// Write the section headers into V.
template<int size, bool big_endian>
unsigned char*
Output_segment::write_section_headers(const Layout* layout,
const Stringpool* secnamepool,
unsigned char* v,
unsigned int *pshndx
ACCEPT_SIZE_ENDIAN) const
{
// Every section that is attached to a segment must be attached to a
// PT_LOAD segment, so we only write out section headers for PT_LOAD
// segments.
if (this->type_ != elfcpp::PT_LOAD)
return v;
v = this->write_section_headers_list
SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
layout, secnamepool, &this->output_data_, v, pshndx
SELECT_SIZE_ENDIAN(size, big_endian));
v = this->write_section_headers_list
SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
layout, secnamepool, &this->output_bss_, v, pshndx
SELECT_SIZE_ENDIAN(size, big_endian));
return v;
}
template<int size, bool big_endian>
unsigned char*
Output_segment::write_section_headers_list(const Layout* layout,
const Stringpool* secnamepool,
const Output_data_list* pdl,
unsigned char* v,
unsigned int* pshndx
ACCEPT_SIZE_ENDIAN) const
{
const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
for (Output_data_list::const_iterator p = pdl->begin();
p != pdl->end();
++p)
{
if ((*p)->is_section())
{
const Output_section* ps = static_cast<const Output_section*>(*p);
gold_assert(*pshndx == ps->out_shndx());
elfcpp::Shdr_write<size, big_endian> oshdr(v);
ps->write_header(layout, secnamepool, &oshdr);
v += shdr_size;
++*pshndx;
}
}
return v;
}
// Output_file methods.
Output_file::Output_file(const General_options& options, Target* target)
: options_(options),
target_(target),
name_(options.output_file_name()),
o_(-1),
file_size_(0),
base_(NULL)
{
}
// Open the output file.
void
Output_file::open(off_t file_size)
{
this->file_size_ = file_size;
// Unlink the file first; otherwise the open() may fail if the file
// is busy (e.g. it's an executable that's currently being executed).
//
// However, the linker may be part of a system where a zero-length
// file is created for it to write to, with tight permissions (gcc
// 2.95 did something like this). Unlinking the file would work
// around those permission controls, so we only unlink if the file
// has a non-zero size. We also unlink only regular files to avoid
// trouble with directories/etc.
//
// If we fail, continue; this command is merely a best-effort attempt
// to improve the odds for open().
// FIXME: unlink the file if it's a symlink, even a symlink to a dir.
// Or do we want to follow the symlink and unlink its target?
struct stat s;
if (::stat(this->name_, &s) == 0 && s.st_size != 0 && S_ISREG(s.st_mode))
::unlink(this->name_);
int mode = parameters->output_is_object() ? 0666 : 0777;
int o = ::open(this->name_, O_RDWR | O_CREAT | O_TRUNC, mode);
if (o < 0)
{
fprintf(stderr, _("%s: %s: open: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
this->o_ = o;
// Write out one byte to make the file the right size.
if (::lseek(o, file_size - 1, SEEK_SET) < 0)
{
fprintf(stderr, _("%s: %s: lseek: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
char b = 0;
if (::write(o, &b, 1) != 1)
{
fprintf(stderr, _("%s: %s: write: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
// Map the file into memory.
void* base = ::mmap(NULL, file_size, PROT_READ | PROT_WRITE,
MAP_SHARED, o, 0);
if (base == MAP_FAILED)
{
fprintf(stderr, _("%s: %s: mmap: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
this->base_ = static_cast<unsigned char*>(base);
}
// Close the output file.
void
Output_file::close()
{
if (::munmap(this->base_, this->file_size_) < 0)
{
fprintf(stderr, _("%s: %s: munmap: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
this->base_ = NULL;
if (::close(this->o_) < 0)
{
fprintf(stderr, _("%s: %s: close: %s\n"),
program_name, this->name_, strerror(errno));
gold_exit(false);
}
this->o_ = -1;
}
// 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
off_t
Output_section::add_input_section<32, false>(
Relobj* object,
unsigned int shndx,
const char* secname,
const elfcpp::Shdr<32, false>& shdr);
#endif
#ifdef HAVE_TARGET_32_BIG
template
off_t
Output_section::add_input_section<32, true>(
Relobj* object,
unsigned int shndx,
const char* secname,
const elfcpp::Shdr<32, true>& shdr);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
off_t
Output_section::add_input_section<64, false>(
Relobj* object,
unsigned int shndx,
const char* secname,
const elfcpp::Shdr<64, false>& shdr);
#endif
#ifdef HAVE_TARGET_64_BIG
template
off_t
Output_section::add_input_section<64, true>(
Relobj* object,
unsigned int shndx,
const char* secname,
const elfcpp::Shdr<64, true>& shdr);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Output_data_reloc<elfcpp::SHT_REL, false, 32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Output_data_reloc<elfcpp::SHT_REL, false, 32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Output_data_reloc<elfcpp::SHT_REL, false, 64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Output_data_reloc<elfcpp::SHT_REL, false, 64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Output_data_reloc<elfcpp::SHT_REL, true, 32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Output_data_reloc<elfcpp::SHT_REL, true, 32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Output_data_reloc<elfcpp::SHT_REL, true, 64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Output_data_reloc<elfcpp::SHT_REL, true, 64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Output_data_reloc<elfcpp::SHT_RELA, false, 32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Output_data_reloc<elfcpp::SHT_RELA, false, 32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Output_data_reloc<elfcpp::SHT_RELA, false, 64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Output_data_reloc<elfcpp::SHT_RELA, false, 64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Output_data_reloc<elfcpp::SHT_RELA, true, 32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Output_data_reloc<elfcpp::SHT_RELA, true, 32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Output_data_reloc<elfcpp::SHT_RELA, true, 64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Output_data_reloc<elfcpp::SHT_RELA, true, 64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Output_data_got<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Output_data_got<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Output_data_got<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Output_data_got<64, true>;
#endif
} // End namespace gold.
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