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binutils-gdb/gold/dynobj.h
2016-01-01 23:00:01 +10:30

689 lines
19 KiB
C++

// dynobj.h -- dynamic object support for gold -*- C++ -*-
// Copyright (C) 2006-2016 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.
#ifndef GOLD_DYNOBJ_H
#define GOLD_DYNOBJ_H
#include <vector>
#include "stringpool.h"
#include "object.h"
namespace gold
{
class Version_script_info;
// A dynamic object (ET_DYN). This is an abstract base class itself.
// The implementations is the template class Sized_dynobj.
class Dynobj : public Object
{
public:
// We keep a list of all the DT_NEEDED entries we find.
typedef std::vector<std::string> Needed;
Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0);
// Return the name to use in a DT_NEEDED entry for this object.
const char*
soname() const
{ return this->soname_.c_str(); }
// Return the list of DT_NEEDED strings.
const Needed&
needed() const
{ return this->needed_; }
// Return whether this dynamic object has any DT_NEEDED entries
// which were not seen during the link.
bool
has_unknown_needed_entries() const
{
gold_assert(this->unknown_needed_ != UNKNOWN_NEEDED_UNSET);
return this->unknown_needed_ == UNKNOWN_NEEDED_TRUE;
}
// Set whether this dynamic object has any DT_NEEDED entries which
// were not seen during the link.
void
set_has_unknown_needed_entries(bool set)
{
gold_assert(this->unknown_needed_ == UNKNOWN_NEEDED_UNSET);
this->unknown_needed_ = set ? UNKNOWN_NEEDED_TRUE : UNKNOWN_NEEDED_FALSE;
}
// Return the word size of the object file.
int
elfsize() const
{ gold_unreachable(); }
// Return TRUE if this is a big-endian object file.
bool
is_big_endian() const
{ gold_unreachable(); }
// Compute the ELF hash code for a string.
static uint32_t
elf_hash(const char*);
// Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
// DYNSYMS is the global dynamic symbols. LOCAL_DYNSYM_COUNT is the
// number of local dynamic symbols, which is the index of the first
// dynamic gobal symbol.
static void
create_elf_hash_table(const std::vector<Symbol*>& dynsyms,
unsigned int local_dynsym_count,
unsigned char** pphash,
unsigned int* phashlen);
// Create a GNU hash table, setting *PPHASH and *PHASHLEN. DYNSYMS
// is the global dynamic symbols. LOCAL_DYNSYM_COUNT is the number
// of local dynamic symbols, which is the index of the first dynamic
// gobal symbol.
static void
create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,
unsigned int local_dynsym_count,
unsigned char** pphash, unsigned int* phashlen);
protected:
// Return a pointer to this object.
virtual Dynobj*
do_dynobj()
{ return this; }
// Set the DT_SONAME string.
void
set_soname_string(const char* s)
{ this->soname_.assign(s); }
// Add an entry to the list of DT_NEEDED strings.
void
add_needed(const char* s)
{ this->needed_.push_back(std::string(s)); }
private:
// Compute the GNU hash code for a string.
static uint32_t
gnu_hash(const char*);
// Compute the number of hash buckets to use.
static unsigned int
compute_bucket_count(const std::vector<uint32_t>& hashcodes,
bool for_gnu_hash_table);
// Sized version of create_elf_hash_table.
template<int size, bool big_endian>
static void
sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
const std::vector<uint32_t>& chain,
unsigned char* phash,
unsigned int hashlen);
// Sized version of create_gnu_hash_table.
template<int size, bool big_endian>
static void
sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
const std::vector<uint32_t>& dynsym_hashvals,
unsigned int unhashed_dynsym_count,
unsigned char** pphash,
unsigned int* phashlen);
// Values for the has_unknown_needed_entries_ field.
enum Unknown_needed
{
UNKNOWN_NEEDED_UNSET,
UNKNOWN_NEEDED_TRUE,
UNKNOWN_NEEDED_FALSE
};
// The DT_SONAME name, if any.
std::string soname_;
// The list of DT_NEEDED entries.
Needed needed_;
// Whether this dynamic object has any DT_NEEDED entries not seen
// during the link.
Unknown_needed unknown_needed_;
};
// A dynamic object, size and endian specific version.
template<int size, bool big_endian>
class Sized_dynobj : public Dynobj
{
public:
typedef typename Sized_relobj_file<size, big_endian>::Symbols Symbols;
Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
const typename elfcpp::Ehdr<size, big_endian>&);
// Set up the object file based on TARGET.
void
setup();
// Read the symbols.
void
do_read_symbols(Read_symbols_data*);
// Lay out the input sections.
void
do_layout(Symbol_table*, Layout*, Read_symbols_data*);
// Add the symbols to the symbol table.
void
do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);
Archive::Should_include
do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
std::string* why);
// Iterate over global symbols, calling a visitor class V for each.
void
do_for_all_global_symbols(Read_symbols_data* sd,
Library_base::Symbol_visitor_base* v);
// Iterate over local symbols, calling a visitor class V for each GOT offset
// associated with a local symbol.
void
do_for_all_local_got_entries(Got_offset_list::Visitor* v) const;
// Get the size of a section.
uint64_t
do_section_size(unsigned int shndx)
{ return this->elf_file_.section_size(shndx); }
// Get the name of a section.
std::string
do_section_name(unsigned int shndx) const
{ return this->elf_file_.section_name(shndx); }
// Return a view of the contents of a section. Set *PLEN to the
// size.
const unsigned char*
do_section_contents(unsigned int shndx, section_size_type* plen,
bool cache)
{
Location loc(this->elf_file_.section_contents(shndx));
*plen = convert_to_section_size_type(loc.data_size);
if (*plen == 0)
{
static const unsigned char empty[1] = { '\0' };
return empty;
}
return this->get_view(loc.file_offset, *plen, true, cache);
}
// Return section flags.
uint64_t
do_section_flags(unsigned int shndx)
{ return this->elf_file_.section_flags(shndx); }
// Not used for dynobj.
uint64_t
do_section_entsize(unsigned int )
{ gold_unreachable(); }
// Return section address.
uint64_t
do_section_address(unsigned int shndx)
{ return this->elf_file_.section_addr(shndx); }
// Return section type.
unsigned int
do_section_type(unsigned int shndx)
{ return this->elf_file_.section_type(shndx); }
// Return the section link field.
unsigned int
do_section_link(unsigned int shndx)
{ return this->elf_file_.section_link(shndx); }
// Return the section link field.
unsigned int
do_section_info(unsigned int shndx)
{ return this->elf_file_.section_info(shndx); }
// Return the section alignment.
uint64_t
do_section_addralign(unsigned int shndx)
{ return this->elf_file_.section_addralign(shndx); }
// Return the Xindex structure to use.
Xindex*
do_initialize_xindex();
// Get symbol counts.
void
do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
// Get the global symbols.
const Symbols*
do_get_global_symbols() const
{ return this->symbols_; }
protected:
// Read the symbols. This is common code for all target-specific
// overrides of do_read_symbols().
void
base_read_symbols(Read_symbols_data*);
private:
// For convenience.
typedef Sized_dynobj<size, big_endian> This;
static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
typedef elfcpp::Shdr<size, big_endian> Shdr;
typedef elfcpp::Dyn<size, big_endian> Dyn;
// Adjust a section index if necessary.
unsigned int
adjust_shndx(unsigned int shndx)
{
if (shndx >= elfcpp::SHN_LORESERVE)
shndx += this->elf_file_.large_shndx_offset();
return shndx;
}
// Find the dynamic symbol table and the version sections, given the
// section headers.
void
find_dynsym_sections(const unsigned char* pshdrs,
unsigned int* pversym_shndx,
unsigned int* pverdef_shndx,
unsigned int* pverneed_shndx,
unsigned int* pdynamic_shndx);
// Read the dynamic symbol section SHNDX.
void
read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
elfcpp::SHT type, unsigned int link,
File_view** view, section_size_type* view_size,
unsigned int* view_info);
// Read the dynamic tags.
void
read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
unsigned int strtab_shndx, const unsigned char* strtabu,
off_t strtab_size);
// Mapping from version number to version name.
typedef std::vector<const char*> Version_map;
// Create the version map.
void
make_version_map(Read_symbols_data* sd, Version_map*) const;
// Add version definitions to the version map.
void
make_verdef_map(Read_symbols_data* sd, Version_map*) const;
// Add version references to the version map.
void
make_verneed_map(Read_symbols_data* sd, Version_map*) const;
// Add an entry to the version map.
void
set_version_map(Version_map*, unsigned int ndx, const char* name) const;
// General access to the ELF file.
elfcpp::Elf_file<size, big_endian, Object> elf_file_;
// The section index of the dynamic symbol table.
unsigned int dynsym_shndx_;
// The entries in the symbol table for the symbols. We only keep
// this if we need it to print symbol information.
Symbols* symbols_;
// Number of defined symbols.
size_t defined_count_;
};
// A base class for Verdef and Verneed_version which just handles the
// version index which will be stored in the SHT_GNU_versym section.
class Version_base
{
public:
Version_base()
: index_(-1U)
{ }
virtual
~Version_base()
{ }
// Return the version index.
unsigned int
index() const
{
gold_assert(this->index_ != -1U);
return this->index_;
}
// Set the version index.
void
set_index(unsigned int index)
{
gold_assert(this->index_ == -1U);
this->index_ = index;
}
// Clear the weak flag in a version definition.
virtual void
clear_weak() = 0;
private:
Version_base(const Version_base&);
Version_base& operator=(const Version_base&);
// The index of the version definition or reference.
unsigned int index_;
};
// This class handles a version being defined in the file we are
// generating.
class Verdef : public Version_base
{
public:
Verdef(const char* name, const std::vector<std::string>& deps,
bool is_base, bool is_weak, bool is_info, bool is_symbol_created)
: name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
is_info_(is_info), is_symbol_created_(is_symbol_created)
{ }
// Return the version name.
const char*
name() const
{ return this->name_; }
// Return the number of dependencies.
unsigned int
count_dependencies() const
{ return this->deps_.size(); }
// Add a dependency to this version. The NAME should be
// canonicalized in the dynamic Stringpool.
void
add_dependency(const char* name)
{ this->deps_.push_back(name); }
// Return whether this definition is weak.
bool
is_weak() const
{ return this->is_weak_; }
// Clear the weak flag.
void
clear_weak()
{ this->is_weak_ = false; }
// Return whether this definition is informational.
bool
is_info() const
{ return this->is_info_; }
// Return whether a version symbol has been created for this
// definition.
bool
is_symbol_created() const
{ return this->is_symbol_created_; }
// Write contents to buffer.
template<int size, bool big_endian>
unsigned char*
write(const Stringpool*, bool is_last, unsigned char*) const;
private:
Verdef(const Verdef&);
Verdef& operator=(const Verdef&);
// The type of the list of version dependencies. Each dependency
// should be canonicalized in the dynamic Stringpool.
typedef std::vector<std::string> Deps;
// The name of this version. This should be canonicalized in the
// dynamic Stringpool.
const char* name_;
// A list of other versions which this version depends upon.
Deps deps_;
// Whether this is the base version.
bool is_base_;
// Whether this version is weak.
bool is_weak_;
// Whether this version is informational.
bool is_info_;
// Whether a version symbol has been created.
bool is_symbol_created_;
};
// A referened version. This will be associated with a filename by
// Verneed.
class Verneed_version : public Version_base
{
public:
Verneed_version(const char* version)
: version_(version)
{ }
// Return the version name.
const char*
version() const
{ return this->version_; }
// Clear the weak flag. This is invalid for a reference.
void
clear_weak()
{ gold_unreachable(); }
private:
Verneed_version(const Verneed_version&);
Verneed_version& operator=(const Verneed_version&);
const char* version_;
};
// Version references in a single dynamic object.
class Verneed
{
public:
Verneed(const char* filename)
: filename_(filename), need_versions_()
{ }
~Verneed();
// Return the file name.
const char*
filename() const
{ return this->filename_; }
// Return the number of versions.
unsigned int
count_versions() const
{ return this->need_versions_.size(); }
// Add a version name. The name should be canonicalized in the
// dynamic Stringpool. If the name is already present, this does
// nothing.
Verneed_version*
add_name(const char* name);
// Set the version indexes, starting at INDEX. Return the updated
// INDEX.
unsigned int
finalize(unsigned int index);
// Write contents to buffer.
template<int size, bool big_endian>
unsigned char*
write(const Stringpool*, bool is_last, unsigned char*) const;
private:
Verneed(const Verneed&);
Verneed& operator=(const Verneed&);
// The type of the list of version names. Each name should be
// canonicalized in the dynamic Stringpool.
typedef std::vector<Verneed_version*> Need_versions;
// The filename of the dynamic object. This should be
// canonicalized in the dynamic Stringpool.
const char* filename_;
// The list of version names.
Need_versions need_versions_;
};
// This class handles version definitions and references which go into
// the output file.
class Versions
{
public:
Versions(const Version_script_info&, Stringpool*);
~Versions();
// SYM is going into the dynamic symbol table and has a version.
// Record the appropriate version information.
void
record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
// Set the version indexes. DYNSYM_INDEX is the index we should use
// for the next dynamic symbol. We add new dynamic symbols to SYMS
// and return an updated DYNSYM_INDEX.
unsigned int
finalize(Symbol_table* symtab, unsigned int dynsym_index,
std::vector<Symbol*>* syms);
// Return whether there are any version definitions.
bool
any_defs() const
{ return !this->defs_.empty(); }
// Return whether there are any version references.
bool
any_needs() const
{ return !this->needs_.empty(); }
// Build an allocated buffer holding the contents of the symbol
// version section (.gnu.version).
template<int size, bool big_endian>
void
symbol_section_contents(const Symbol_table*, const Stringpool*,
unsigned int local_symcount,
const std::vector<Symbol*>& syms,
unsigned char**, unsigned int*) const;
// Build an allocated buffer holding the contents of the version
// definition section (.gnu.version_d).
template<int size, bool big_endian>
void
def_section_contents(const Stringpool*, unsigned char**,
unsigned int* psize, unsigned int* pentries) const;
// Build an allocated buffer holding the contents of the version
// reference section (.gnu.version_r).
template<int size, bool big_endian>
void
need_section_contents(const Stringpool*, unsigned char**,
unsigned int* psize, unsigned int* pentries) const;
const Version_script_info&
version_script() const
{ return this->version_script_; }
private:
Versions(const Versions&);
Versions& operator=(const Versions&);
// The type of the list of version definitions.
typedef std::vector<Verdef*> Defs;
// The type of the list of version references.
typedef std::vector<Verneed*> Needs;
// Handle a symbol SYM defined with version VERSION.
void
add_def(Stringpool*, const Symbol* sym, const char* version,
Stringpool::Key);
// Add a reference to version NAME in file FILENAME.
void
add_need(Stringpool*, const char* filename, const char* name,
Stringpool::Key);
// Get the dynamic object to use for SYM.
Dynobj*
get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
// Return the version index to use for SYM.
unsigned int
version_index(const Symbol_table*, const Stringpool*,
const Symbol* sym) const;
// Define the base version of a shared library.
void
define_base_version(Stringpool* dynpool);
// We keep a hash table mapping canonicalized name/version pairs to
// a version base.
typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
struct Version_table_hash
{
size_t
operator()(const Key& k) const
{ return k.first + k.second; }
};
struct Version_table_eq
{
bool
operator()(const Key& k1, const Key& k2) const
{ return k1.first == k2.first && k1.second == k2.second; }
};
typedef Unordered_map<Key, Version_base*, Version_table_hash,
Version_table_eq> Version_table;
// The version definitions.
Defs defs_;
// The version references.
Needs needs_;
// The mapping from a canonicalized version/filename pair to a
// version index. The filename may be NULL.
Version_table version_table_;
// Whether the version indexes have been set.
bool is_finalized_;
// Contents of --version-script, if passed, or NULL.
const Version_script_info& version_script_;
// Whether we need to insert a base version. This is only used for
// shared libraries and is cleared when the base version is defined.
bool needs_base_version_;
};
} // End namespace gold.
#endif // !defined(GOLD_DYNOBJ_H)