| // object.h -- support for an object file for linking in gold -*- C++ -*- |
| |
| #ifndef GOLD_OBJECT_H |
| #define GOLD_OBJECT_H |
| |
| #include <string> |
| #include <vector> |
| |
| #include "elfcpp.h" |
| #include "elfcpp_file.h" |
| #include "fileread.h" |
| #include "target.h" |
| |
| namespace gold |
| { |
| |
| class General_options; |
| class Stringpool; |
| class Layout; |
| class Output_section; |
| class Output_file; |
| class Dynobj; |
| |
| // Data to pass from read_symbols() to add_symbols(). |
| |
| struct Read_symbols_data |
| { |
| // Section headers. |
| File_view* section_headers; |
| // Section names. |
| File_view* section_names; |
| // Size of section name data in bytes. |
| off_t section_names_size; |
| // Symbol data. |
| File_view* symbols; |
| // Size of symbol data in bytes. |
| off_t symbols_size; |
| // Symbol names. |
| File_view* symbol_names; |
| // Size of symbol name data in bytes. |
| off_t symbol_names_size; |
| |
| // Version information. This is only used on dynamic objects. |
| // Version symbol data (from SHT_GNU_versym section). |
| File_view* versym; |
| off_t versym_size; |
| // Version definition data (from SHT_GNU_verdef section). |
| File_view* verdef; |
| off_t verdef_size; |
| unsigned int verdef_info; |
| // Needed version data (from SHT_GNU_verneed section). |
| File_view* verneed; |
| off_t verneed_size; |
| unsigned int verneed_info; |
| }; |
| |
| // Data about a single relocation section. This is read in |
| // read_relocs and processed in scan_relocs. |
| |
| struct Section_relocs |
| { |
| // Index of reloc section. |
| unsigned int reloc_shndx; |
| // Index of section that relocs apply to. |
| unsigned int data_shndx; |
| // Contents of reloc section. |
| File_view* contents; |
| // Reloc section type. |
| unsigned int sh_type; |
| // Number of reloc entries. |
| size_t reloc_count; |
| }; |
| |
| // Relocations in an object file. This is read in read_relocs and |
| // processed in scan_relocs. |
| |
| struct Read_relocs_data |
| { |
| typedef std::vector<Section_relocs> Relocs_list; |
| // The relocations. |
| Relocs_list relocs; |
| // The local symbols. |
| File_view* local_symbols; |
| }; |
| |
| // Object is an abstract base class which represents either a 32-bit |
| // or a 64-bit input object. This can be a regular object file |
| // (ET_REL) or a shared object (ET_DYN). |
| |
| class Object |
| { |
| public: |
| // NAME is the name of the object as we would report it to the user |
| // (e.g., libfoo.a(bar.o) if this is in an archive. INPUT_FILE is |
| // used to read the file. OFFSET is the offset within the input |
| // file--0 for a .o or .so file, something else for a .a file. |
| Object(const std::string& name, Input_file* input_file, bool is_dynamic, |
| off_t offset = 0) |
| : name_(name), input_file_(input_file), offset_(offset), shnum_(-1U), |
| is_dynamic_(is_dynamic), target_(NULL) |
| { } |
| |
| virtual ~Object() |
| { } |
| |
| // Return the name of the object as we would report it to the tuser. |
| const std::string& |
| name() const |
| { return this->name_; } |
| |
| // Return whether this is a dynamic object. |
| bool |
| is_dynamic() const |
| { return this->is_dynamic_; } |
| |
| // Return the target structure associated with this object. |
| Target* |
| target() const |
| { return this->target_; } |
| |
| // Lock the underlying file. |
| void |
| lock() |
| { this->input_file_->file().lock(); } |
| |
| // Unlock the underlying file. |
| void |
| unlock() |
| { this->input_file_->file().unlock(); } |
| |
| // Return whether the underlying file is locked. |
| bool |
| is_locked() const |
| { return this->input_file_->file().is_locked(); } |
| |
| // Return the sized target structure associated with this object. |
| // This is like the target method but it returns a pointer of |
| // appropriate checked type. |
| template<int size, bool big_endian> |
| Sized_target<size, big_endian>* |
| sized_target(ACCEPT_SIZE_ENDIAN_ONLY); |
| |
| // Get the number of sections. |
| unsigned int |
| shnum() const |
| { return this->shnum_; } |
| |
| // Return a view of the contents of a section. Set *PLEN to the |
| // size. |
| const unsigned char* |
| section_contents(unsigned int shndx, off_t* plen); |
| |
| // Return the name of a section given a section index. This is only |
| // used for error messages. |
| std::string |
| section_name(unsigned int shndx) |
| { return this->do_section_name(shndx); } |
| |
| // Return the section flags given a section index. |
| uint64_t |
| section_flags(unsigned int shndx) |
| { return this->do_section_flags(shndx); } |
| |
| // Read the symbol information. |
| void |
| read_symbols(Read_symbols_data* sd) |
| { return this->do_read_symbols(sd); } |
| |
| // Pass sections which should be included in the link to the Layout |
| // object, and record where the sections go in the output file. |
| void |
| layout(const General_options& options, Symbol_table* symtab, |
| Layout* layout, Read_symbols_data* sd) |
| { this->do_layout(options, symtab, layout, sd); } |
| |
| // Add symbol information to the global symbol table. |
| void |
| add_symbols(Symbol_table* symtab, Read_symbols_data* sd) |
| { this->do_add_symbols(symtab, sd); } |
| |
| // Functions and types for the elfcpp::Elf_file interface. This |
| // permit us to use Object as the File template parameter for |
| // elfcpp::Elf_file. |
| |
| // The View class is returned by view. It must support a single |
| // method, data(). This is trivial, because get_view does what we |
| // need. |
| class View |
| { |
| public: |
| View(const unsigned char* p) |
| : p_(p) |
| { } |
| |
| const unsigned char* |
| data() const |
| { return this->p_; } |
| |
| private: |
| const unsigned char* p_; |
| }; |
| |
| // Return a View. |
| View |
| view(off_t file_offset, off_t data_size) |
| { return View(this->get_view(file_offset, data_size)); } |
| |
| // Report an error. |
| void |
| error(const char* format, ...) ATTRIBUTE_PRINTF_2; |
| |
| // A location in the file. |
| struct Location |
| { |
| off_t file_offset; |
| off_t data_size; |
| |
| Location(off_t fo, off_t ds) |
| : file_offset(fo), data_size(ds) |
| { } |
| }; |
| |
| // Get a View given a Location. |
| View view(Location loc) |
| { return View(this->get_view(loc.file_offset, loc.data_size)); } |
| |
| protected: |
| // Read the symbols--implemented by child class. |
| virtual void |
| do_read_symbols(Read_symbols_data*) = 0; |
| |
| // Lay out sections--implemented by child class. |
| virtual void |
| do_layout(const General_options&, Symbol_table*, Layout*, |
| Read_symbols_data*) = 0; |
| |
| // Add symbol information to the global symbol table--implemented by |
| // child class. |
| virtual void |
| do_add_symbols(Symbol_table*, Read_symbols_data*) = 0; |
| |
| // Return the location of the contents of a section. Implemented by |
| // child class. |
| virtual Location |
| do_section_contents(unsigned int shndx) = 0; |
| |
| // Get the name of a section--implemented by child class. |
| virtual std::string |
| do_section_name(unsigned int shndx) = 0; |
| |
| // Get section flags--implemented by child class. |
| virtual uint64_t |
| do_section_flags(unsigned int shndx) = 0; |
| |
| // Get the file. |
| Input_file* |
| input_file() const |
| { return this->input_file_; } |
| |
| // Get the offset into the file. |
| off_t |
| offset() const |
| { return this->offset_; } |
| |
| // Get a view into the underlying file. |
| const unsigned char* |
| get_view(off_t start, off_t size) |
| { return this->input_file_->file().get_view(start + this->offset_, size); } |
| |
| // Get a lasting view into the underlying file. |
| File_view* |
| get_lasting_view(off_t start, off_t size) |
| { |
| return this->input_file_->file().get_lasting_view(start + this->offset_, |
| size); |
| } |
| |
| // Read data from the underlying file. |
| void |
| read(off_t start, off_t size, void* p) |
| { this->input_file_->file().read(start + this->offset_, size, p); } |
| |
| // Set the target. |
| void |
| set_target(int machine, int size, bool big_endian, int osabi, |
| int abiversion); |
| |
| // Set the number of sections. |
| void |
| set_shnum(int shnum) |
| { this->shnum_ = shnum; } |
| |
| // Functions used by both Sized_relobj and Sized_dynobj. |
| |
| // Read the section data into a Read_symbols_data object. |
| template<int size, bool big_endian> |
| void |
| read_section_data(elfcpp::Elf_file<size, big_endian, Object>*, |
| Read_symbols_data*); |
| |
| // If NAME is the name of a special .gnu.warning section, arrange |
| // for the warning to be issued. SHNDX is the section index. |
| // Return whether it is a warning section. |
| bool |
| handle_gnu_warning_section(const char* name, unsigned int shndx, |
| Symbol_table*); |
| |
| private: |
| // This class may not be copied. |
| Object(const Object&); |
| Object& operator=(const Object&); |
| |
| // Name of object as printed to user. |
| std::string name_; |
| // For reading the file. |
| Input_file* input_file_; |
| // Offset within the file--0 for an object file, non-0 for an |
| // archive. |
| off_t offset_; |
| // Number of input sections. |
| unsigned int shnum_; |
| // Whether this is a dynamic object. |
| bool is_dynamic_; |
| // Target functions--may be NULL if the target is not known. |
| Target* target_; |
| }; |
| |
| // Implement sized_target inline for efficiency. This approach breaks |
| // static type checking, but is made safe using asserts. |
| |
| template<int size, bool big_endian> |
| inline Sized_target<size, big_endian>* |
| Object::sized_target(ACCEPT_SIZE_ENDIAN_ONLY) |
| { |
| gold_assert(this->target_->get_size() == size); |
| gold_assert(this->target_->is_big_endian() ? big_endian : !big_endian); |
| return static_cast<Sized_target<size, big_endian>*>(this->target_); |
| } |
| |
| // A regular object (ET_REL). This is an abstract base class itself. |
| // The implementations is the template class Sized_relobj. |
| |
| class Relobj : public Object |
| { |
| public: |
| Relobj(const std::string& name, Input_file* input_file, off_t offset = 0) |
| : Object(name, input_file, false, offset) |
| { } |
| |
| // Read the relocs. |
| void |
| read_relocs(Read_relocs_data* rd) |
| { return this->do_read_relocs(rd); } |
| |
| // Scan the relocs and adjust the symbol table. |
| void |
| scan_relocs(const General_options& options, Symbol_table* symtab, |
| Layout* layout, Read_relocs_data* rd) |
| { return this->do_scan_relocs(options, symtab, layout, rd); } |
| |
| // Initial local symbol processing: set the offset where local |
| // symbol information will be stored; add local symbol names to |
| // *POOL; return the new local symbol index. |
| unsigned int |
| finalize_local_symbols(unsigned int index, off_t off, Stringpool* pool) |
| { return this->do_finalize_local_symbols(index, off, pool); } |
| |
| // Relocate the input sections and write out the local symbols. |
| void |
| relocate(const General_options& options, const Symbol_table* symtab, |
| const Layout* layout, Output_file* of) |
| { return this->do_relocate(options, symtab, layout, of); } |
| |
| // Return whether an input section is being included in the link. |
| bool |
| is_section_included(unsigned int shndx) const |
| { |
| gold_assert(shndx < this->map_to_output_.size()); |
| return this->map_to_output_[shndx].output_section != NULL; |
| } |
| |
| // Given a section index, return the corresponding Output_section |
| // (which will be NULL if the section is not included in the link) |
| // and set *POFF to the offset within that section. |
| inline Output_section* |
| output_section(unsigned int shndx, off_t* poff); |
| |
| // Set the offset of an input section within its output section. |
| void |
| set_section_offset(unsigned int shndx, off_t off) |
| { |
| gold_assert(shndx < this->map_to_output_.size()); |
| this->map_to_output_[shndx].offset = off; |
| } |
| |
| protected: |
| // What we need to know to map an input section to an output |
| // section. We keep an array of these, one for each input section, |
| // indexed by the input section number. |
| struct Map_to_output |
| { |
| // The output section. This is NULL if the input section is to be |
| // discarded. |
| Output_section* output_section; |
| // The offset within the output section. |
| off_t offset; |
| }; |
| |
| // Read the relocs--implemented by child class. |
| virtual void |
| do_read_relocs(Read_relocs_data*) = 0; |
| |
| // Scan the relocs--implemented by child class. |
| virtual void |
| do_scan_relocs(const General_options&, Symbol_table*, Layout*, |
| Read_relocs_data*) = 0; |
| |
| // Finalize local symbols--implemented by child class. |
| virtual unsigned int |
| do_finalize_local_symbols(unsigned int, off_t, Stringpool*) = 0; |
| |
| // Relocate the input sections and write out the local |
| // symbols--implemented by child class. |
| virtual void |
| do_relocate(const General_options& options, const Symbol_table* symtab, |
| const Layout*, Output_file* of) = 0; |
| |
| // Return the vector mapping input sections to output sections. |
| std::vector<Map_to_output>& |
| map_to_output() |
| { return this->map_to_output_; } |
| |
| private: |
| // Mapping from input sections to output section. |
| std::vector<Map_to_output> map_to_output_; |
| }; |
| |
| // Implement Object::output_section inline for efficiency. |
| inline Output_section* |
| Relobj::output_section(unsigned int shndx, off_t* poff) |
| { |
| gold_assert(shndx < this->map_to_output_.size()); |
| const Map_to_output& mo(this->map_to_output_[shndx]); |
| *poff = mo.offset; |
| return mo.output_section; |
| } |
| |
| // A regular object file. This is size and endian specific. |
| |
| template<int size, bool big_endian> |
| class Sized_relobj : public Relobj |
| { |
| public: |
| typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; |
| typedef std::vector<Address> Local_values; |
| |
| Sized_relobj(const std::string& name, Input_file* input_file, off_t offset, |
| const typename elfcpp::Ehdr<size, big_endian>&); |
| |
| ~Sized_relobj(); |
| |
| // Set up the object file based on the ELF header. |
| void |
| setup(const typename elfcpp::Ehdr<size, big_endian>&); |
| |
| // Return the index of local symbol SYM in the ordinary symbol |
| // table. A value of -1U means that the symbol is not being output. |
| unsigned int |
| symtab_index(unsigned int sym) const |
| { |
| gold_assert(sym < this->local_indexes_.size()); |
| gold_assert(this->local_indexes_[sym] != 0); |
| return this->local_indexes_[sym]; |
| } |
| |
| // Read the symbols. |
| void |
| do_read_symbols(Read_symbols_data*); |
| |
| // Lay out the input sections. |
| void |
| do_layout(const General_options&, Symbol_table*, Layout*, |
| Read_symbols_data*); |
| |
| // Add the symbols to the symbol table. |
| void |
| do_add_symbols(Symbol_table*, Read_symbols_data*); |
| |
| // Read the relocs. |
| void |
| do_read_relocs(Read_relocs_data*); |
| |
| // Scan the relocs and adjust the symbol table. |
| void |
| do_scan_relocs(const General_options&, Symbol_table*, Layout*, |
| Read_relocs_data*); |
| |
| // Finalize the local symbols. |
| unsigned int |
| do_finalize_local_symbols(unsigned int, off_t, Stringpool*); |
| |
| // Relocate the input sections and write out the local symbols. |
| void |
| do_relocate(const General_options& options, const Symbol_table* symtab, |
| const Layout*, Output_file* of); |
| |
| // Get the name of a section. |
| std::string |
| do_section_name(unsigned int shndx) |
| { return this->elf_file_.section_name(shndx); } |
| |
| // Return the location of the contents of a section. |
| Object::Location |
| do_section_contents(unsigned int shndx) |
| { return this->elf_file_.section_contents(shndx); } |
| |
| // Return section flags. |
| uint64_t |
| do_section_flags(unsigned int shndx) |
| { return this->elf_file_.section_flags(shndx); } |
| |
| // Return the appropriate Sized_target structure. |
| Sized_target<size, big_endian>* |
| sized_target() |
| { |
| return this->Object::sized_target |
| SELECT_SIZE_ENDIAN_NAME(size, big_endian) ( |
| SELECT_SIZE_ENDIAN_ONLY(size, big_endian)); |
| } |
| |
| private: |
| // For convenience. |
| typedef Sized_relobj<size, big_endian> This; |
| static const int ehdr_size = elfcpp::Elf_sizes<size>::ehdr_size; |
| static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size; |
| static const int sym_size = elfcpp::Elf_sizes<size>::sym_size; |
| typedef elfcpp::Shdr<size, big_endian> Shdr; |
| |
| // Find the SHT_SYMTAB section, given the section headers. |
| void |
| find_symtab(const unsigned char* pshdrs); |
| |
| // Whether to include a section group in the link. |
| bool |
| include_section_group(Layout*, unsigned int, |
| const elfcpp::Shdr<size, big_endian>&, |
| std::vector<bool>*); |
| |
| // Whether to include a linkonce section in the link. |
| bool |
| include_linkonce_section(Layout*, const char*, |
| const elfcpp::Shdr<size, big_endian>&); |
| |
| // Views and sizes when relocating. |
| struct View_size |
| { |
| unsigned char* view; |
| typename elfcpp::Elf_types<size>::Elf_Addr address; |
| off_t offset; |
| off_t view_size; |
| }; |
| |
| typedef std::vector<View_size> Views; |
| |
| // Write section data to the output file. Record the views and |
| // sizes in VIEWS for use when relocating. |
| void |
| write_sections(const unsigned char* pshdrs, Output_file*, Views*); |
| |
| // Relocate the sections in the output file. |
| void |
| relocate_sections(const General_options& options, const Symbol_table*, |
| const Layout*, const unsigned char* pshdrs, Views*); |
| |
| // Write out the local symbols. |
| void |
| write_local_symbols(Output_file*, const Stringpool*); |
| |
| // General access to the ELF file. |
| elfcpp::Elf_file<size, big_endian, Object> elf_file_; |
| // Index of SHT_SYMTAB section. |
| unsigned int symtab_shndx_; |
| // The number of local symbols. |
| unsigned int local_symbol_count_; |
| // The number of local symbols which go into the output file. |
| unsigned int output_local_symbol_count_; |
| // The entries in the symbol table for the external symbols. |
| Symbol** symbols_; |
| // File offset for local symbols. |
| off_t local_symbol_offset_; |
| // Values of local symbols. |
| Local_values local_values_; |
| // Indexes of local symbols in the output file; -1U if not present. |
| std::vector<unsigned int> local_indexes_; |
| }; |
| |
| // A class to manage the list of all objects. |
| |
| class Input_objects |
| { |
| public: |
| Input_objects() |
| : relobj_list_(), dynobj_list_(), target_(NULL), sonames_() |
| { } |
| |
| // The type of the list of input relocateable objects. |
| typedef std::vector<Relobj*> Relobj_list; |
| typedef Relobj_list::const_iterator Relobj_iterator; |
| |
| // The type of the list of input dynamic objects. |
| typedef std::vector<Dynobj*> Dynobj_list; |
| typedef Dynobj_list::const_iterator Dynobj_iterator; |
| |
| // Add an object to the list. Return true if all is well, or false |
| // if this object should be ignored. |
| bool |
| add_object(Object*); |
| |
| // Get the target we should use for the output file. |
| Target* |
| target() const |
| { return this->target_; } |
| |
| // Iterate over all regular objects. |
| |
| Relobj_iterator |
| relobj_begin() const |
| { return this->relobj_list_.begin(); } |
| |
| Relobj_iterator |
| relobj_end() const |
| { return this->relobj_list_.end(); } |
| |
| // Iterate over all dynamic objects. |
| |
| Dynobj_iterator |
| dynobj_begin() const |
| { return this->dynobj_list_.begin(); } |
| |
| Dynobj_iterator |
| dynobj_end() const |
| { return this->dynobj_list_.end(); } |
| |
| // Return whether we have seen any dynamic objects. |
| bool |
| any_dynamic() const |
| { return !this->dynobj_list_.empty(); } |
| |
| private: |
| Input_objects(const Input_objects&); |
| Input_objects& operator=(const Input_objects&); |
| |
| // The list of ordinary objects included in the link. |
| Relobj_list relobj_list_; |
| // The list of dynamic objects included in the link. |
| Dynobj_list dynobj_list_; |
| // The target. |
| Target* target_; |
| // SONAMEs that we have seen. |
| Unordered_set<std::string> sonames_; |
| }; |
| |
| // Some of the information we pass to the relocation routines. We |
| // group this together to avoid passing a dozen different arguments. |
| |
| template<int size, bool big_endian> |
| struct Relocate_info |
| { |
| // Command line options. |
| const General_options* options; |
| // Symbol table. |
| const Symbol_table* symtab; |
| // Layout. |
| const Layout* layout; |
| // Object being relocated. |
| Sized_relobj<size, big_endian>* object; |
| // Number of local symbols. |
| unsigned int local_symbol_count; |
| // Values of local symbols. |
| const typename Sized_relobj<size, big_endian>::Local_values* local_values; |
| // Global symbols. |
| const Symbol* const * symbols; |
| // Section index of relocation section. |
| unsigned int reloc_shndx; |
| // Section index of section being relocated. |
| unsigned int data_shndx; |
| |
| // Return a string showing the location of a relocation. This is |
| // only used for error messages. |
| std::string |
| location(size_t relnum, off_t reloffset) const; |
| }; |
| |
| // Return an Object appropriate for the input file. P is BYTES long, |
| // and holds the ELF header. |
| |
| extern Object* |
| make_elf_object(const std::string& name, Input_file*, |
| off_t offset, const unsigned char* p, |
| off_t bytes); |
| |
| } // end namespace gold |
| |
| #endif // !defined(GOLD_OBJECT_H) |