mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-11-27 03:54:41 +08:00
Keep track of weak aliases, so that overriding environ works.
This commit is contained in:
Ian Lance Taylor
parent
ad435a2465
commit
aeddab66fe
@ -71,6 +71,35 @@ Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
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this->symsize_ = sym.get_st_size();
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}
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// Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
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// VERSION. This handles all aliases of TOSYM.
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template<int size, bool big_endian>
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void
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Symbol_table::override(Sized_symbol<size>* tosym,
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const elfcpp::Sym<size, big_endian>& fromsym,
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Object* object, const char* version)
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{
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tosym->override(fromsym, object, version);
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if (tosym->has_alias())
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{
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Symbol* sym = this->weak_aliases_[tosym];
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gold_assert(sym != NULL);
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Sized_symbol<size>* ssym;
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ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
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SELECT_SIZE(size));
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do
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{
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ssym->override(fromsym, object, version);
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sym = this->weak_aliases_[ssym];
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gold_assert(sym != NULL);
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ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
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sym SELECT_SIZE(size));
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}
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while (ssym != tosym);
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}
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}
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// The resolve functions build a little code for each symbol.
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// Bit 0: 0 for global, 1 for weak.
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// Bit 1: 0 for regular object, 1 for shared object
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@ -175,7 +204,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
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{
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typename Sized_symbol<size>::Size_type tosize = to->symsize();
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to->override(sym, object, version);
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this->override(to, sym, object, version);
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if (adjust_common_sizes && tosize > to->symsize())
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to->set_symsize(tosize);
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@ -636,6 +665,34 @@ Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
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this->symsize_ = from->symsize_;
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}
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// Override TOSYM with the special symbol FROMSYM. This handles all
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// aliases of TOSYM.
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template<int size>
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void
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Symbol_table::override_with_special(Sized_symbol<size>* tosym,
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const Sized_symbol<size>* fromsym)
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{
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tosym->override_with_special(fromsym);
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if (tosym->has_alias())
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{
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Symbol* sym = this->weak_aliases_[tosym];
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gold_assert(sym != NULL);
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Sized_symbol<size>* ssym;
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ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
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SELECT_SIZE(size));
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do
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{
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ssym->override_with_special(fromsym);
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sym = this->weak_aliases_[ssym];
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gold_assert(sym != NULL);
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ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
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sym SELECT_SIZE(size));
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}
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while (ssym != tosym);
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}
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}
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// Instantiate the templates we need. We could use the configure
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// script to restrict this to only the ones needed for implemented
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// targets.
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@ -683,13 +740,15 @@ Symbol_table::resolve<64, true>(
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#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
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template
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void
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Sized_symbol<32>::override_with_special(const Sized_symbol<32>*);
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Symbol_table::override_with_special<32>(Sized_symbol<32>*,
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const Sized_symbol<32>*);
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#endif
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#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
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template
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void
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Sized_symbol<64>::override_with_special(const Sized_symbol<64>*);
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Symbol_table::override_with_special<64>(Sized_symbol<64>*,
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const Sized_symbol<64>*);
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#endif
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} // End namespace gold.
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236
gold/symtab.cc
236
gold/symtab.cc
@ -59,6 +59,7 @@ Symbol::init_fields(const char* name, const char* version,
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this->is_target_special_ = false;
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this->is_def_ = false;
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this->is_forwarder_ = false;
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this->has_alias_ = false;
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this->needs_dynsym_entry_ = false;
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this->in_reg_ = false;
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this->in_dyn_ = false;
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@ -319,7 +320,7 @@ Symbol_table::resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
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esym.put_st_info(from->binding(), from->type());
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esym.put_st_other(from->visibility(), from->nonvis());
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esym.put_st_shndx(from->shndx());
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Symbol_table::resolve(to, esym.sym(), from->object(), version);
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this->resolve(to, esym.sym(), from->object(), version);
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if (from->in_reg())
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to->set_in_reg();
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if (from->in_dyn())
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@ -350,7 +351,7 @@ Symbol_table::resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
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// forwarders.
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template<int size, bool big_endian>
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Symbol*
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Sized_symbol<size>*
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Symbol_table::add_from_object(Object* object,
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const char *name,
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Stringpool::Key name_key,
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@ -392,7 +393,7 @@ Symbol_table::add_from_object(Object* object,
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was_undefined = ret->is_undefined();
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was_common = ret->is_common();
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Symbol_table::resolve(ret, sym, object, version);
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this->resolve(ret, sym, object, version);
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if (def)
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{
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@ -432,7 +433,7 @@ Symbol_table::add_from_object(Object* object,
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ret = this->get_sized_symbol SELECT_SIZE_NAME(size) (
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insdef.first->second
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SELECT_SIZE(size));
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Symbol_table::resolve(ret, sym, object, version);
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this->resolve(ret, sym, object, version);
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ins.first->second = ret;
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}
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else
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@ -541,7 +542,7 @@ Symbol_table::add_from_relobj(
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// this is the default version.
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const char* ver = strchr(name, '@');
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Symbol* res;
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Sized_symbol<size>* res;
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if (ver == NULL)
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{
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Stringpool::Key name_key;
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@ -598,6 +599,16 @@ Symbol_table::add_from_dynobj(
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const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
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// We keep a list of all STT_OBJECT symbols, so that we can resolve
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// weak aliases. This is necessary because if the dynamic object
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// provides the same variable under two names, one of which is a
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// weak definition, and the regular object refers to the weak
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// definition, we have to put both the weak definition and the
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// strong definition into the dynamic symbol table. Given a weak
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// definition, the only way that we can find the corresponding
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// strong definition, if any, is to search the symbol table.
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std::vector<Sized_symbol<size>*> object_symbols;
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const unsigned char* p = syms;
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const unsigned char* vs = versym;
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for (size_t i = 0; i < count; ++i, p += sym_size, vs += 2)
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@ -618,79 +629,172 @@ Symbol_table::add_from_dynobj(
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const char* name = sym_names + st_name;
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Sized_symbol<size>* res;
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if (versym == NULL)
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{
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Stringpool::Key name_key;
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name = this->namepool_.add(name, true, &name_key);
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this->add_from_object(dynobj, name, name_key, NULL, 0,
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false, sym);
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continue;
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res = this->add_from_object(dynobj, name, name_key, NULL, 0,
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false, sym);
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}
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// Read the version information.
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unsigned int v = elfcpp::Swap<16, big_endian>::readval(vs);
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bool hidden = (v & elfcpp::VERSYM_HIDDEN) != 0;
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v &= elfcpp::VERSYM_VERSION;
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// The Sun documentation says that V can be VER_NDX_LOCAL, or
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// VER_NDX_GLOBAL, or a version index. The meaning of
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// VER_NDX_LOCAL is defined as "Symbol has local scope." The
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// old GNU linker will happily generate VER_NDX_LOCAL for an
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// undefined symbol. I don't know what the Sun linker will
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// generate.
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if (v == static_cast<unsigned int>(elfcpp::VER_NDX_LOCAL)
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&& sym.get_st_shndx() != elfcpp::SHN_UNDEF)
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else
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{
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// This symbol should not be visible outside the object.
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continue;
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// Read the version information.
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unsigned int v = elfcpp::Swap<16, big_endian>::readval(vs);
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bool hidden = (v & elfcpp::VERSYM_HIDDEN) != 0;
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v &= elfcpp::VERSYM_VERSION;
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// The Sun documentation says that V can be VER_NDX_LOCAL,
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// or VER_NDX_GLOBAL, or a version index. The meaning of
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// VER_NDX_LOCAL is defined as "Symbol has local scope."
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// The old GNU linker will happily generate VER_NDX_LOCAL
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// for an undefined symbol. I don't know what the Sun
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// linker will generate.
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if (v == static_cast<unsigned int>(elfcpp::VER_NDX_LOCAL)
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&& sym.get_st_shndx() != elfcpp::SHN_UNDEF)
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{
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// This symbol should not be visible outside the object.
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continue;
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}
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// At this point we are definitely going to add this symbol.
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Stringpool::Key name_key;
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name = this->namepool_.add(name, true, &name_key);
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if (v == static_cast<unsigned int>(elfcpp::VER_NDX_LOCAL)
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|| v == static_cast<unsigned int>(elfcpp::VER_NDX_GLOBAL))
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{
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// This symbol does not have a version.
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res = this->add_from_object(dynobj, name, name_key, NULL, 0,
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false, sym);
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}
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else
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{
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if (v >= version_map->size())
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{
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dynobj->error(_("versym for symbol %zu out of range: %u"),
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i, v);
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continue;
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}
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const char* version = (*version_map)[v];
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if (version == NULL)
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{
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dynobj->error(_("versym for symbol %zu has no name: %u"),
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i, v);
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continue;
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}
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Stringpool::Key version_key;
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version = this->namepool_.add(version, true, &version_key);
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// If this is an absolute symbol, and the version name
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// and symbol name are the same, then this is the
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// version definition symbol. These symbols exist to
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// support using -u to pull in particular versions. We
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// do not want to record a version for them.
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if (sym.get_st_shndx() == elfcpp::SHN_ABS
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&& name_key == version_key)
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res = this->add_from_object(dynobj, name, name_key, NULL, 0,
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false, sym);
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else
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{
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const bool def = (!hidden
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&& (sym.get_st_shndx()
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!= elfcpp::SHN_UNDEF));
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res = this->add_from_object(dynobj, name, name_key, version,
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version_key, def, sym);
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}
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}
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}
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// At this point we are definitely going to add this symbol.
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Stringpool::Key name_key;
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name = this->namepool_.add(name, true, &name_key);
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if (sym.get_st_shndx() != elfcpp::SHN_UNDEF
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&& sym.get_st_type() == elfcpp::STT_OBJECT)
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object_symbols.push_back(res);
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}
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if (v == static_cast<unsigned int>(elfcpp::VER_NDX_LOCAL)
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|| v == static_cast<unsigned int>(elfcpp::VER_NDX_GLOBAL))
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this->record_weak_aliases(&object_symbols);
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}
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// This is used to sort weak aliases. We sort them first by section
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// index, then by offset, then by weak ahead of strong.
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template<int size>
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class Weak_alias_sorter
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{
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public:
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bool operator()(const Sized_symbol<size>*, const Sized_symbol<size>*) const;
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};
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template<int size>
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bool
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Weak_alias_sorter<size>::operator()(const Sized_symbol<size>* s1,
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const Sized_symbol<size>* s2) const
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{
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if (s1->shndx() != s2->shndx())
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return s1->shndx() < s2->shndx();
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if (s1->value() != s2->value())
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return s1->value() < s2->value();
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if (s1->binding() != s2->binding())
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{
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if (s1->binding() == elfcpp::STB_WEAK)
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return true;
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if (s2->binding() == elfcpp::STB_WEAK)
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return false;
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}
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return std::string(s1->name()) < std::string(s2->name());
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}
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// SYMBOLS is a list of object symbols from a dynamic object. Look
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// for any weak aliases, and record them so that if we add the weak
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// alias to the dynamic symbol table, we also add the corresponding
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// strong symbol.
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template<int size>
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void
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Symbol_table::record_weak_aliases(std::vector<Sized_symbol<size>*>* symbols)
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{
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// Sort the vector by section index, then by offset, then by weak
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// ahead of strong.
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std::sort(symbols->begin(), symbols->end(), Weak_alias_sorter<size>());
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// Walk through the vector. For each weak definition, record
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// aliases.
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for (typename std::vector<Sized_symbol<size>*>::const_iterator p =
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symbols->begin();
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p != symbols->end();
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++p)
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{
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if ((*p)->binding() != elfcpp::STB_WEAK)
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continue;
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// Build a circular list of weak aliases. Each symbol points to
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// the next one in the circular list.
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Sized_symbol<size>* from_sym = *p;
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typename std::vector<Sized_symbol<size>*>::const_iterator q;
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for (q = p + 1; q != symbols->end(); ++q)
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{
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// This symbol does not have a version.
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this->add_from_object(dynobj, name, name_key, NULL, 0, false, sym);
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continue;
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if ((*q)->shndx() != from_sym->shndx()
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|| (*q)->value() != from_sym->value())
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break;
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this->weak_aliases_[from_sym] = *q;
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from_sym->set_has_alias();
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from_sym = *q;
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}
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if (v >= version_map->size())
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if (from_sym != *p)
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{
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dynobj->error(_("versym for symbol %zu out of range: %u"), i, v);
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continue;
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this->weak_aliases_[from_sym] = *p;
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from_sym->set_has_alias();
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}
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const char* version = (*version_map)[v];
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if (version == NULL)
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{
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dynobj->error(_("versym for symbol %zu has no name: %u"), i, v);
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continue;
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}
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Stringpool::Key version_key;
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version = this->namepool_.add(version, true, &version_key);
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// If this is an absolute symbol, and the version name and
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// symbol name are the same, then this is the version definition
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// symbol. These symbols exist to support using -u to pull in
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// particular versions. We do not want to record a version for
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// them.
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if (sym.get_st_shndx() == elfcpp::SHN_ABS && name_key == version_key)
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{
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this->add_from_object(dynobj, name, name_key, NULL, 0, false, sym);
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continue;
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}
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const bool def = !hidden && sym.get_st_shndx() != elfcpp::SHN_UNDEF;
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this->add_from_object(dynobj, name, name_key, version, version_key,
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def, sym);
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p = q - 1;
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}
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}
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@ -868,7 +972,7 @@ Symbol_table::do_define_in_output_data(
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if (oldsym != NULL
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&& Symbol_table::should_override_with_special(oldsym))
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oldsym->override_with_special(sym);
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this->override_with_special(oldsym, sym);
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return sym;
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}
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@ -962,7 +1066,7 @@ Symbol_table::do_define_in_output_segment(
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if (oldsym != NULL
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&& Symbol_table::should_override_with_special(oldsym))
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oldsym->override_with_special(sym);
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this->override_with_special(oldsym, sym);
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return sym;
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}
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@ -1049,7 +1153,7 @@ Symbol_table::do_define_as_constant(
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if (oldsym != NULL
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&& Symbol_table::should_override_with_special(oldsym))
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oldsym->override_with_special(sym);
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this->override_with_special(oldsym, sym);
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return sym;
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}
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@ -195,6 +195,17 @@ class Symbol
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set_forwarder()
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{ this->is_forwarder_ = true; }
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// Return whether this symbol has an alias in the weak aliases table
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// in Symbol_table.
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bool
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has_alias() const
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{ return this->has_alias_; }
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// Mark this symbol as having an alias.
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void
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set_has_alias()
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{ this->has_alias_ = true; }
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// Return whether this symbol needs an entry in the dynamic symbol
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// table.
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bool
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@ -528,6 +539,9 @@ class Symbol
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// It forwards to the symbol found in the forwarders_ map of
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// Symbol_table.
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bool is_forwarder_ : 1;
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// True if the symbol has an alias in the weak_aliases table in
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// Symbol_table.
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bool has_alias_ : 1;
|
||||
// True if this symbol needs to be in the dynamic symbol table.
|
||||
bool needs_dynsym_entry_ : 1;
|
||||
// True if we've seen this symbol in a regular object.
|
||||
@ -924,20 +938,20 @@ class Symbol_table
|
||||
|
||||
// Add a symbol.
|
||||
template<int size, bool big_endian>
|
||||
Symbol*
|
||||
Sized_symbol<size>*
|
||||
add_from_object(Object*, const char *name, Stringpool::Key name_key,
|
||||
const char *version, Stringpool::Key version_key,
|
||||
bool def, const elfcpp::Sym<size, big_endian>& sym);
|
||||
|
||||
// Resolve symbols.
|
||||
template<int size, bool big_endian>
|
||||
static void
|
||||
void
|
||||
resolve(Sized_symbol<size>* to,
|
||||
const elfcpp::Sym<size, big_endian>& sym,
|
||||
Object*, const char* version);
|
||||
|
||||
template<int size, bool big_endian>
|
||||
static void
|
||||
void
|
||||
resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
|
||||
const char* version ACCEPT_SIZE_ENDIAN);
|
||||
|
||||
@ -946,11 +960,29 @@ class Symbol_table
|
||||
static bool
|
||||
should_override(const Symbol*, unsigned int, Object*, bool*);
|
||||
|
||||
// Override a symbol.
|
||||
template<int size, bool big_endian>
|
||||
void
|
||||
override(Sized_symbol<size>* tosym,
|
||||
const elfcpp::Sym<size, big_endian>& fromsym,
|
||||
Object* object, const char* version);
|
||||
|
||||
// Whether we should override a symbol with a special symbol which
|
||||
// is automatically defined by the linker.
|
||||
static bool
|
||||
should_override_with_special(const Symbol*);
|
||||
|
||||
// Override a symbol with a special symbol.
|
||||
template<int size>
|
||||
void
|
||||
override_with_special(Sized_symbol<size>* tosym,
|
||||
const Sized_symbol<size>* fromsym);
|
||||
|
||||
// Record all weak alias sets for a dynamic object.
|
||||
template<int size>
|
||||
void
|
||||
record_weak_aliases(std::vector<Sized_symbol<size>*>*);
|
||||
|
||||
// Define a special symbol.
|
||||
template<int size, bool big_endian>
|
||||
Sized_symbol<size>*
|
||||
@ -1077,6 +1109,10 @@ class Symbol_table
|
||||
// Forwarding symbols.
|
||||
Unordered_map<const Symbol*, Symbol*> forwarders_;
|
||||
|
||||
// Weak aliases. A symbol in this list points to the next alias.
|
||||
// The aliases point to each other in a circular list.
|
||||
Unordered_map<Symbol*, Symbol*> weak_aliases_;
|
||||
|
||||
// We don't expect there to be very many common symbols, so we keep
|
||||
// a list of them. When we find a common symbol we add it to this
|
||||
// list. It is possible that by the time we process the list the
|
||||
|
||||
Loading…
Reference in New Issue
Block a user