// object.h -- support for an object file for linking in gold -*- C++ -*- #ifndef GOLD_OBJECT_H #define GOLD_OBJECT_H #include #include #include #include #include "elfcpp.h" #include "fileread.h" #include "target.h" #include "symtab.h" namespace gold { class General_options; class Stringpool; class Layout; class Output_section; class Output_file; // 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; }; // 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 Relocs_list; // The relocations. Relocs_list relocs; // The local symbols. File_view* local_symbols; }; // Object is an interface 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). The actual instantiations are // Sized_object<32> and Sized_object<64> 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_(0), is_dynamic_(is_dynamic), target_(NULL), map_to_output_() { } 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 Sized_target* sized_target(ACCEPT_SIZE_ENDIAN_ONLY); // 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(Layout* lay, Read_symbols_data* sd) { this->do_layout(lay, 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); } // 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, Read_relocs_data* rd) { return this->do_scan_relocs(options, symtab, rd); } // Initial local symbol processing: set the offset where local // symbol information will be stored; add local symbol names to // *POOL; return the offset following the local symbols. off_t finalize_local_symbols(off_t off, Stringpool* pool) { return this->do_finalize_local_symbols(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 shnum) const { assert(shnum < this->map_to_output_.size()); return this->map_to_output_[shnum].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 shnum, off_t* poff); // Return the name of a section given a section index. This is only // used for error messages. std::string section_name(unsigned int shnum) { return this->do_section_name(shnum); } 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 symbols--implemented by child class. virtual void do_read_symbols(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; // 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*, Read_relocs_data*) = 0; // Lay out sections--implemented by child class. virtual void do_layout(Layout*, Read_symbols_data*) = 0; // Finalize local symbols--implemented by child class. virtual off_t do_finalize_local_symbols(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; // Get the name of a section--implemented by child class. virtual std::string do_section_name(unsigned int shnum) = 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); // Get the number of sections. unsigned int shnum() const { return this->shnum_; } // Set the number of sections. void set_shnum(int shnum) { this->shnum_ = shnum; } // Set the target. void set_target(Target* target) { this->target_ = target; } // Read data from the underlying file. void read(off_t start, off_t size, void* p); // Get a lasting view into the underlying file. File_view* get_lasting_view(off_t start, off_t size); // Return the vector mapping input sections to output sections. std::vector& map_to_output() { return this->map_to_output_; } 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_; // Mapping from input sections to output section. std::vector map_to_output_; }; // Implement sized_target inline for efficiency. This approach breaks // static type checking, but is made safe using asserts. template inline Sized_target* Object::sized_target(ACCEPT_SIZE_ENDIAN_ONLY) { assert(this->target_->get_size() == size); assert(this->target_->is_big_endian() ? big_endian : !big_endian); return static_cast*>(this->target_); } // Implement Object::output_section inline for efficiency. inline Output_section* Object::output_section(unsigned int shnum, off_t* poff) { assert(shnum < this->map_to_output_.size()); const Map_to_output& mo(this->map_to_output_[shnum]); *poff = mo.offset; return mo.output_section; } // A regular object file. This is size and endian specific. template class Sized_object : public Object { public: Sized_object(const std::string& name, Input_file* input_file, off_t offset, const typename elfcpp::Ehdr&); ~Sized_object(); // Set up the object file based on the ELF header. void setup(const typename elfcpp::Ehdr&); // Read the symbols. void do_read_symbols(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*, Read_relocs_data*); // Lay out the input sections. void do_layout(Layout*, Read_symbols_data*); // Finalize the local symbols. off_t do_finalize_local_symbols(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 shnum); // Return the appropriate Sized_target structure. Sized_target* sized_target() { return this->Object::sized_target SELECT_SIZE_ENDIAN_NAME ( SELECT_SIZE_ENDIAN_ONLY(size, big_endian)); } private: // This object may not be copied. Sized_object(const Sized_object&); Sized_object& operator=(const Sized_object&); // For convenience. typedef Sized_object This; static const int ehdr_size = elfcpp::Elf_sizes::ehdr_size; static const int shdr_size = elfcpp::Elf_sizes::shdr_size; static const int sym_size = elfcpp::Elf_sizes::sym_size; typedef elfcpp::Shdr Shdr; // Read the section header for section SHNUM. const unsigned char* section_header(unsigned int shnum); // Whether to include a section group in the link. bool include_section_group(Layout*, unsigned int, const elfcpp::Shdr&, std::vector*); // Whether to include a linkonce section in the link. bool include_linkonce_section(Layout*, const char*, const elfcpp::Shdr&); // Views and sizes when relocating. struct View_size { unsigned char* view; typename elfcpp::Elf_types::Elf_Addr address; off_t offset; off_t view_size; }; typedef std::vector 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*); // If non-NULL, a view of the section header data. File_view* section_headers_; // ELF file header e_flags field. unsigned int flags_; // File offset of section header table. off_t shoff_; // Offset of SHT_STRTAB section holding section names. unsigned int shstrndx_; // Index of SHT_SYMTAB section. unsigned int symtab_shnum_; // 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. typename elfcpp::Elf_types::Elf_Addr *values_; }; // A class to manage the list of all objects. class Input_objects { public: Input_objects() : object_list_(), target_(NULL), any_dynamic_(false) { } // The type of the list of input objects. typedef std::list Object_list; // Add an object to the list. void add_object(Object*); // Get the target we should use for the output file. Target* target() const { return this->target_; } // Iterate over all objects. Object_list::const_iterator begin() const { return this->object_list_.begin(); } Object_list::const_iterator end() const { return this->object_list_.end(); } // Return whether we have seen any dynamic objects. bool any_dynamic() const { return this->any_dynamic_; } private: Input_objects(const Input_objects&); Input_objects& operator=(const Input_objects&); Object_list object_list_; Target* target_; bool any_dynamic_; }; // Some of the information we pass to the relocation routines. We // group this together to avoid passing a dozen different arguments. template struct Relocate_info { // Command line options. const General_options* options; // Symbol table. const Symbol_table* symtab; // Layout. const Layout* layout; // Object being relocated. Sized_object* object; // Number of local symbols. unsigned int local_symbol_count; // Values of local symbols. typename elfcpp::Elf_types::Elf_Addr *values; // Global symbols. Symbol** 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)