| @section Targets |
| |
| |
| @strong{Description}@* |
| Each port of BFD to a different machine requries the creation |
| of a target back end. All the back end provides to the root |
| part of BFD is a structure containing pointers to functions |
| which perform certain low level operations on files. BFD |
| translates the applications's requests through a pointer into |
| calls to the back end routines. |
| |
| When a file is opened with @code{bfd_openr}, its format and |
| target are unknown. BFD uses various mechanisms to determine |
| how to interpret the file. The operations performed are: |
| |
| @itemize @bullet |
| |
| @item |
| Create a BFD by calling the internal routine |
| @code{_bfd_new_bfd}, then call @code{bfd_find_target} with the |
| target string supplied to @code{bfd_openr} and the new BFD pointer. |
| |
| @item |
| If a null target string was provided to @code{bfd_find_target}, |
| look up the environment variable @code{GNUTARGET} and use |
| that as the target string. |
| |
| @item |
| If the target string is still @code{NULL}, or the target string is |
| @code{default}, then use the first item in the target vector |
| as the target type, and set @code{target_defaulted} in the BFD to |
| cause @code{bfd_check_format} to loop through all the targets. |
| @xref{bfd_target}. @xref{Formats}. |
| |
| @item |
| Otherwise, inspect the elements in the target vector |
| one by one, until a match on target name is found. When found, |
| use it. |
| |
| @item |
| Otherwise return the error @code{bfd_error_invalid_target} to |
| @code{bfd_openr}. |
| |
| @item |
| @code{bfd_openr} attempts to open the file using |
| @code{bfd_open_file}, and returns the BFD. |
| @end itemize |
| Once the BFD has been opened and the target selected, the file |
| format may be determined. This is done by calling |
| @code{bfd_check_format} on the BFD with a suggested format. |
| If @code{target_defaulted} has been set, each possible target |
| type is tried to see if it recognizes the specified format. |
| @code{bfd_check_format} returns @code{true} when the caller guesses right. |
| @menu |
| * bfd_target:: |
| @end menu |
| |
| @node bfd_target, , Targets, Targets |
| |
| @subsection bfd_target |
| |
| |
| @strong{Description}@* |
| This structure contains everything that BFD knows about a |
| target. It includes things like its byte order, name, and which |
| routines to call to do various operations. |
| |
| Every BFD points to a target structure with its @code{xvec} |
| member. |
| |
| The macros below are used to dispatch to functions through the |
| @code{bfd_target} vector. They are used in a number of macros further |
| down in @file{bfd.h}, and are also used when calling various |
| routines by hand inside the BFD implementation. The @var{arglist} |
| argument must be parenthesized; it contains all the arguments |
| to the called function. |
| |
| They make the documentation (more) unpleasant to read, so if |
| someone wants to fix this and not break the above, please do. |
| @example |
| #define BFD_SEND(bfd, message, arglist) \ |
| ((*((bfd)->xvec->message)) arglist) |
| |
| #ifdef DEBUG_BFD_SEND |
| #undef BFD_SEND |
| #define BFD_SEND(bfd, message, arglist) \ |
| (((bfd) && (bfd)->xvec && (bfd)->xvec->message) ? \ |
| ((*((bfd)->xvec->message)) arglist) : \ |
| (bfd_assert (__FILE__,__LINE__), NULL)) |
| #endif |
| @end example |
| For operations which index on the BFD format: |
| @example |
| #define BFD_SEND_FMT(bfd, message, arglist) \ |
| (((bfd)->xvec->message[(int) ((bfd)->format)]) arglist) |
| |
| #ifdef DEBUG_BFD_SEND |
| #undef BFD_SEND_FMT |
| #define BFD_SEND_FMT(bfd, message, arglist) \ |
| (((bfd) && (bfd)->xvec && (bfd)->xvec->message) ? \ |
| (((bfd)->xvec->message[(int) ((bfd)->format)]) arglist) : \ |
| (bfd_assert (__FILE__,__LINE__), NULL)) |
| #endif |
| @end example |
| This is the structure which defines the type of BFD this is. The |
| @code{xvec} member of the struct @code{bfd} itself points here. Each |
| module that implements access to a different target under BFD, |
| defines one of these. |
| |
| FIXME, these names should be rationalised with the names of |
| the entry points which call them. Too bad we can't have one |
| macro to define them both! |
| @example |
| enum bfd_flavour @{ |
| bfd_target_unknown_flavour, |
| bfd_target_aout_flavour, |
| bfd_target_coff_flavour, |
| bfd_target_ecoff_flavour, |
| bfd_target_xcoff_flavour, |
| bfd_target_elf_flavour, |
| bfd_target_ieee_flavour, |
| bfd_target_nlm_flavour, |
| bfd_target_oasys_flavour, |
| bfd_target_tekhex_flavour, |
| bfd_target_srec_flavour, |
| bfd_target_ihex_flavour, |
| bfd_target_som_flavour, |
| bfd_target_os9k_flavour, |
| bfd_target_versados_flavour, |
| bfd_target_msdos_flavour, |
| bfd_target_ovax_flavour, |
| bfd_target_evax_flavour |
| @}; |
| |
| enum bfd_endian @{ BFD_ENDIAN_BIG, BFD_ENDIAN_LITTLE, BFD_ENDIAN_UNKNOWN @}; |
| |
| /* Forward declaration. */ |
| typedef struct bfd_link_info _bfd_link_info; |
| |
| typedef struct bfd_target |
| @{ |
| @end example |
| Identifies the kind of target, e.g., SunOS4, Ultrix, etc. |
| @example |
| char *name; |
| @end example |
| The "flavour" of a back end is a general indication about the contents |
| of a file. |
| @example |
| enum bfd_flavour flavour; |
| @end example |
| The order of bytes within the data area of a file. |
| @example |
| enum bfd_endian byteorder; |
| @end example |
| The order of bytes within the header parts of a file. |
| @example |
| enum bfd_endian header_byteorder; |
| @end example |
| A mask of all the flags which an executable may have set - |
| from the set @code{BFD_NO_FLAGS}, @code{HAS_RELOC}, ...@code{D_PAGED}. |
| @example |
| flagword object_flags; |
| @end example |
| A mask of all the flags which a section may have set - from |
| the set @code{SEC_NO_FLAGS}, @code{SEC_ALLOC}, ...@code{SET_NEVER_LOAD}. |
| @example |
| flagword section_flags; |
| @end example |
| The character normally found at the front of a symbol |
| (if any), perhaps `_'. |
| @example |
| char symbol_leading_char; |
| @end example |
| The pad character for file names within an archive header. |
| @example |
| char ar_pad_char; |
| @end example |
| The maximum number of characters in an archive header. |
| @example |
| unsigned short ar_max_namelen; |
| @end example |
| Entries for byte swapping for data. These are different from the other |
| entry points, since they don't take a BFD asthe first argument. |
| Certain other handlers could do the same. |
| @example |
| bfd_vma (*bfd_getx64) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_getx_signed_64) PARAMS ((const bfd_byte *)); |
| void (*bfd_putx64) PARAMS ((bfd_vma, bfd_byte *)); |
| bfd_vma (*bfd_getx32) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_getx_signed_32) PARAMS ((const bfd_byte *)); |
| void (*bfd_putx32) PARAMS ((bfd_vma, bfd_byte *)); |
| bfd_vma (*bfd_getx16) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_getx_signed_16) PARAMS ((const bfd_byte *)); |
| void (*bfd_putx16) PARAMS ((bfd_vma, bfd_byte *)); |
| @end example |
| Byte swapping for the headers |
| @example |
| bfd_vma (*bfd_h_getx64) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_h_getx_signed_64) PARAMS ((const bfd_byte *)); |
| void (*bfd_h_putx64) PARAMS ((bfd_vma, bfd_byte *)); |
| bfd_vma (*bfd_h_getx32) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_h_getx_signed_32) PARAMS ((const bfd_byte *)); |
| void (*bfd_h_putx32) PARAMS ((bfd_vma, bfd_byte *)); |
| bfd_vma (*bfd_h_getx16) PARAMS ((const bfd_byte *)); |
| bfd_signed_vma (*bfd_h_getx_signed_16) PARAMS ((const bfd_byte *)); |
| void (*bfd_h_putx16) PARAMS ((bfd_vma, bfd_byte *)); |
| @end example |
| Format dependent routines: these are vectors of entry points |
| within the target vector structure, one for each format to check. |
| |
| Check the format of a file being read. Return a @code{bfd_target *} or zero. |
| @example |
| const struct bfd_target *(*_bfd_check_format[bfd_type_end]) PARAMS ((bfd *)); |
| @end example |
| Set the format of a file being written. |
| @example |
| boolean (*_bfd_set_format[bfd_type_end]) PARAMS ((bfd *)); |
| @end example |
| Write cached information into a file being written, at @code{bfd_close}. |
| @example |
| boolean (*_bfd_write_contents[bfd_type_end]) PARAMS ((bfd *)); |
| @end example |
| The general target vector. These vectors are initialized using the |
| BFD_JUMP_TABLE macros. |
| @example |
| |
| /* Generic entry points. */ |
| #define BFD_JUMP_TABLE_GENERIC(NAME)\ |
| CAT(NAME,_close_and_cleanup),\ |
| CAT(NAME,_bfd_free_cached_info),\ |
| CAT(NAME,_new_section_hook),\ |
| CAT(NAME,_get_section_contents),\ |
| CAT(NAME,_get_section_contents_in_window) |
| |
| /* Called when the BFD is being closed to do any necessary cleanup. */ |
| boolean (*_close_and_cleanup) PARAMS ((bfd *)); |
| /* Ask the BFD to free all cached information. */ |
| boolean (*_bfd_free_cached_info) PARAMS ((bfd *)); |
| /* Called when a new section is created. */ |
| boolean (*_new_section_hook) PARAMS ((bfd *, sec_ptr)); |
| /* Read the contents of a section. */ |
| boolean (*_bfd_get_section_contents) PARAMS ((bfd *, sec_ptr, PTR, |
| file_ptr, bfd_size_type)); |
| boolean (*_bfd_get_section_contents_in_window) |
| PARAMS ((bfd *, sec_ptr, bfd_window *, |
| file_ptr, bfd_size_type)); |
| |
| /* Entry points to copy private data. */ |
| #define BFD_JUMP_TABLE_COPY(NAME)\ |
| CAT(NAME,_bfd_copy_private_bfd_data),\ |
| CAT(NAME,_bfd_merge_private_bfd_data),\ |
| CAT(NAME,_bfd_copy_private_section_data),\ |
| CAT(NAME,_bfd_copy_private_symbol_data),\ |
| CAT(NAME,_bfd_set_private_flags),\ |
| CAT(NAME,_bfd_print_private_bfd_data)\ |
| /* Called to copy BFD general private data from one object file |
| to another. */ |
| boolean (*_bfd_copy_private_bfd_data) PARAMS ((bfd *, bfd *)); |
| /* Called to merge BFD general private data from one object file |
| to a common output file when linking. */ |
| boolean (*_bfd_merge_private_bfd_data) PARAMS ((bfd *, bfd *)); |
| /* Called to copy BFD private section data from one object file |
| to another. */ |
| boolean (*_bfd_copy_private_section_data) PARAMS ((bfd *, sec_ptr, |
| bfd *, sec_ptr)); |
| /* Called to copy BFD private symbol data from one symbol |
| to another. */ |
| boolean (*_bfd_copy_private_symbol_data) PARAMS ((bfd *, asymbol *, |
| bfd *, asymbol *)); |
| /* Called to set private backend flags */ |
| boolean (*_bfd_set_private_flags) PARAMS ((bfd *, flagword)); |
| |
| /* Called to print private BFD data */ |
| boolean (*_bfd_print_private_bfd_data) PARAMS ((bfd *, PTR)); |
| |
| /* Core file entry points. */ |
| #define BFD_JUMP_TABLE_CORE(NAME)\ |
| CAT(NAME,_core_file_failing_command),\ |
| CAT(NAME,_core_file_failing_signal),\ |
| CAT(NAME,_core_file_matches_executable_p) |
| char * (*_core_file_failing_command) PARAMS ((bfd *)); |
| int (*_core_file_failing_signal) PARAMS ((bfd *)); |
| boolean (*_core_file_matches_executable_p) PARAMS ((bfd *, bfd *)); |
| |
| /* Archive entry points. */ |
| #define BFD_JUMP_TABLE_ARCHIVE(NAME)\ |
| CAT(NAME,_slurp_armap),\ |
| CAT(NAME,_slurp_extended_name_table),\ |
| CAT(NAME,_construct_extended_name_table),\ |
| CAT(NAME,_truncate_arname),\ |
| CAT(NAME,_write_armap),\ |
| CAT(NAME,_read_ar_hdr),\ |
| CAT(NAME,_openr_next_archived_file),\ |
| CAT(NAME,_get_elt_at_index),\ |
| CAT(NAME,_generic_stat_arch_elt),\ |
| CAT(NAME,_update_armap_timestamp) |
| boolean (*_bfd_slurp_armap) PARAMS ((bfd *)); |
| boolean (*_bfd_slurp_extended_name_table) PARAMS ((bfd *)); |
| boolean (*_bfd_construct_extended_name_table) |
| PARAMS ((bfd *, char **, bfd_size_type *, const char **)); |
| void (*_bfd_truncate_arname) PARAMS ((bfd *, CONST char *, char *)); |
| boolean (*write_armap) PARAMS ((bfd *arch, |
| unsigned int elength, |
| struct orl *map, |
| unsigned int orl_count, |
| int stridx)); |
| PTR (*_bfd_read_ar_hdr_fn) PARAMS ((bfd *)); |
| bfd * (*openr_next_archived_file) PARAMS ((bfd *arch, bfd *prev)); |
| #define bfd_get_elt_at_index(b,i) BFD_SEND(b, _bfd_get_elt_at_index, (b,i)) |
| bfd * (*_bfd_get_elt_at_index) PARAMS ((bfd *, symindex)); |
| int (*_bfd_stat_arch_elt) PARAMS ((bfd *, struct stat *)); |
| boolean (*_bfd_update_armap_timestamp) PARAMS ((bfd *)); |
| |
| /* Entry points used for symbols. */ |
| #define BFD_JUMP_TABLE_SYMBOLS(NAME)\ |
| CAT(NAME,_get_symtab_upper_bound),\ |
| CAT(NAME,_get_symtab),\ |
| CAT(NAME,_make_empty_symbol),\ |
| CAT(NAME,_print_symbol),\ |
| CAT(NAME,_get_symbol_info),\ |
| CAT(NAME,_bfd_is_local_label_name),\ |
| CAT(NAME,_get_lineno),\ |
| CAT(NAME,_find_nearest_line),\ |
| CAT(NAME,_bfd_make_debug_symbol),\ |
| CAT(NAME,_read_minisymbols),\ |
| CAT(NAME,_minisymbol_to_symbol) |
| long (*_bfd_get_symtab_upper_bound) PARAMS ((bfd *)); |
| long (*_bfd_canonicalize_symtab) PARAMS ((bfd *, |
| struct symbol_cache_entry **)); |
| struct symbol_cache_entry * |
| (*_bfd_make_empty_symbol) PARAMS ((bfd *)); |
| void (*_bfd_print_symbol) PARAMS ((bfd *, PTR, |
| struct symbol_cache_entry *, |
| bfd_print_symbol_type)); |
| #define bfd_print_symbol(b,p,s,e) BFD_SEND(b, _bfd_print_symbol, (b,p,s,e)) |
| void (*_bfd_get_symbol_info) PARAMS ((bfd *, |
| struct symbol_cache_entry *, |
| symbol_info *)); |
| #define bfd_get_symbol_info(b,p,e) BFD_SEND(b, _bfd_get_symbol_info, (b,p,e)) |
| boolean (*_bfd_is_local_label_name) PARAMS ((bfd *, const char *)); |
| |
| alent * (*_get_lineno) PARAMS ((bfd *, struct symbol_cache_entry *)); |
| boolean (*_bfd_find_nearest_line) PARAMS ((bfd *abfd, |
| struct sec *section, struct symbol_cache_entry **symbols, |
| bfd_vma offset, CONST char **file, CONST char **func, |
| unsigned int *line)); |
| /* Back-door to allow format-aware applications to create debug symbols |
| while using BFD for everything else. Currently used by the assembler |
| when creating COFF files. */ |
| asymbol * (*_bfd_make_debug_symbol) PARAMS (( |
| bfd *abfd, |
| void *ptr, |
| unsigned long size)); |
| #define bfd_read_minisymbols(b, d, m, s) \ |
| BFD_SEND (b, _read_minisymbols, (b, d, m, s)) |
| long (*_read_minisymbols) PARAMS ((bfd *, boolean, PTR *, |
| unsigned int *)); |
| #define bfd_minisymbol_to_symbol(b, d, m, f) \ |
| BFD_SEND (b, _minisymbol_to_symbol, (b, d, m, f)) |
| asymbol *(*_minisymbol_to_symbol) PARAMS ((bfd *, boolean, const PTR, |
| asymbol *)); |
| |
| /* Routines for relocs. */ |
| #define BFD_JUMP_TABLE_RELOCS(NAME)\ |
| CAT(NAME,_get_reloc_upper_bound),\ |
| CAT(NAME,_canonicalize_reloc),\ |
| CAT(NAME,_bfd_reloc_type_lookup) |
| long (*_get_reloc_upper_bound) PARAMS ((bfd *, sec_ptr)); |
| long (*_bfd_canonicalize_reloc) PARAMS ((bfd *, sec_ptr, arelent **, |
| struct symbol_cache_entry **)); |
| /* See documentation on reloc types. */ |
| reloc_howto_type * |
| (*reloc_type_lookup) PARAMS ((bfd *abfd, |
| bfd_reloc_code_real_type code)); |
| |
| /* Routines used when writing an object file. */ |
| #define BFD_JUMP_TABLE_WRITE(NAME)\ |
| CAT(NAME,_set_arch_mach),\ |
| CAT(NAME,_set_section_contents) |
| boolean (*_bfd_set_arch_mach) PARAMS ((bfd *, enum bfd_architecture, |
| unsigned long)); |
| boolean (*_bfd_set_section_contents) PARAMS ((bfd *, sec_ptr, PTR, |
| file_ptr, bfd_size_type)); |
| |
| /* Routines used by the linker. */ |
| #define BFD_JUMP_TABLE_LINK(NAME)\ |
| CAT(NAME,_sizeof_headers),\ |
| CAT(NAME,_bfd_get_relocated_section_contents),\ |
| CAT(NAME,_bfd_relax_section),\ |
| CAT(NAME,_bfd_link_hash_table_create),\ |
| CAT(NAME,_bfd_link_add_symbols),\ |
| CAT(NAME,_bfd_final_link),\ |
| CAT(NAME,_bfd_link_split_section),\ |
| CAT(NAME,_bfd_gc_sections) |
| int (*_bfd_sizeof_headers) PARAMS ((bfd *, boolean)); |
| bfd_byte * (*_bfd_get_relocated_section_contents) PARAMS ((bfd *, |
| struct bfd_link_info *, struct bfd_link_order *, |
| bfd_byte *data, boolean relocateable, |
| struct symbol_cache_entry **)); |
| |
| boolean (*_bfd_relax_section) PARAMS ((bfd *, struct sec *, |
| struct bfd_link_info *, boolean *again)); |
| |
| /* Create a hash table for the linker. Different backends store |
| different information in this table. */ |
| struct bfd_link_hash_table *(*_bfd_link_hash_table_create) PARAMS ((bfd *)); |
| |
| /* Add symbols from this object file into the hash table. */ |
| boolean (*_bfd_link_add_symbols) PARAMS ((bfd *, struct bfd_link_info *)); |
| |
| /* Do a link based on the link_order structures attached to each |
| section of the BFD. */ |
| boolean (*_bfd_final_link) PARAMS ((bfd *, struct bfd_link_info *)); |
| |
| /* Should this section be split up into smaller pieces during linking. */ |
| boolean (*_bfd_link_split_section) PARAMS ((bfd *, struct sec *)); |
| |
| /* Remove sections that are not referenced from the output. */ |
| boolean (*_bfd_gc_sections) PARAMS ((bfd *, struct bfd_link_info *)); |
| |
| /* Routines to handle dynamic symbols and relocs. */ |
| #define BFD_JUMP_TABLE_DYNAMIC(NAME)\ |
| CAT(NAME,_get_dynamic_symtab_upper_bound),\ |
| CAT(NAME,_canonicalize_dynamic_symtab),\ |
| CAT(NAME,_get_dynamic_reloc_upper_bound),\ |
| CAT(NAME,_canonicalize_dynamic_reloc) |
| /* Get the amount of memory required to hold the dynamic symbols. */ |
| long (*_bfd_get_dynamic_symtab_upper_bound) PARAMS ((bfd *)); |
| /* Read in the dynamic symbols. */ |
| long (*_bfd_canonicalize_dynamic_symtab) |
| PARAMS ((bfd *, struct symbol_cache_entry **)); |
| /* Get the amount of memory required to hold the dynamic relocs. */ |
| long (*_bfd_get_dynamic_reloc_upper_bound) PARAMS ((bfd *)); |
| /* Read in the dynamic relocs. */ |
| long (*_bfd_canonicalize_dynamic_reloc) |
| PARAMS ((bfd *, arelent **, struct symbol_cache_entry **)); |
| |
| @end example |
| A pointer to an alternative bfd_target in case the current one is not |
| satisfactory. This can happen when the target cpu supports both big |
| and little endian code, and target chosen by the linker has the wrong |
| endianness. The function open_output() in ld/ldlang.c uses this field |
| to find an alternative output format that is suitable. |
| @example |
| /* Opposite endian version of this target. */ |
| const struct bfd_target * alternative_target; |
| |
| @end example |
| Data for use by back-end routines, which isn't generic enough to belong |
| in this structure. |
| @example |
| PTR backend_data; |
| |
| @} bfd_target; |
| @end example |
| |
| @findex bfd_set_default_target |
| @subsubsection @code{bfd_set_default_target} |
| @strong{Synopsis} |
| @example |
| boolean bfd_set_default_target (const char *name); |
| @end example |
| @strong{Description}@* |
| Set the default target vector to use when recognizing a BFD. |
| This takes the name of the target, which may be a BFD target |
| name or a configuration triplet. |
| |
| @findex bfd_find_target |
| @subsubsection @code{bfd_find_target} |
| @strong{Synopsis} |
| @example |
| const bfd_target *bfd_find_target(CONST char *target_name, bfd *abfd); |
| @end example |
| @strong{Description}@* |
| Return a pointer to the transfer vector for the object target |
| named @var{target_name}. If @var{target_name} is @code{NULL}, choose the |
| one in the environment variable @code{GNUTARGET}; if that is null or not |
| defined, then choose the first entry in the target list. |
| Passing in the string "default" or setting the environment |
| variable to "default" will cause the first entry in the target |
| list to be returned, and "target_defaulted" will be set in the |
| BFD. This causes @code{bfd_check_format} to loop over all the |
| targets to find the one that matches the file being read. |
| |
| @findex bfd_target_list |
| @subsubsection @code{bfd_target_list} |
| @strong{Synopsis} |
| @example |
| const char **bfd_target_list(void); |
| @end example |
| @strong{Description}@* |
| Return a freshly malloced NULL-terminated |
| vector of the names of all the valid BFD targets. Do not |
| modify the names. |
| |
| @findex bfd_seach_for_target |
| @subsubsection @code{bfd_seach_for_target} |
| @strong{Synopsis} |
| @example |
| const bfd_target * bfd_search_for_target (int (* search_func) (const bfd_target *, void *), void *); |
| @end example |
| @strong{Description}@* |
| Return a pointer to the first transfer vector in the list of |
| transfer vectors maintained by BFD that produces a non-zero |
| result when passed to the function @var{search_func}. The |
| parameter @var{data} is passed, unexamined, to the search |
| function. |
| |