include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2017 Free Software Foundation, Inc.
   3    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #ifndef BFDLINK_H
  23 #define BFDLINK_H
  24
  25 /* Which symbols to strip during a link.  */
  26 enum bfd_link_strip
  27 {
  28   strip_none,           /* Don't strip any symbols.  */
  29   strip_debugger,       /* Strip debugging symbols.  */
  30   strip_some,           /* keep_hash is the list of symbols to keep.  */
  31   strip_all             /* Strip all symbols.  */
  32 };
  33
  34 /* Which local symbols to discard during a link.  This is irrelevant
  35    if strip_all is used.  */
  36 enum bfd_link_discard
  37 {
  38   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  39                            sections.  */
  40   discard_none,         /* Don't discard any locals.  */
  41   discard_l,            /* Discard local temporary symbols.  */
  42   discard_all           /* Discard all locals.  */
  43 };
  44
  45 /* Whether to generate ELF common symbols with the STT_COMMON type
  46    during a relocatable link.  */
  47 enum bfd_link_elf_stt_common
  48 {
  49   unchanged,
  50   elf_stt_common,
  51   no_elf_stt_common
  52 };
  53
  54 /* Describes the type of hash table entry structure being used.
  55    Different hash table structure have different fields and so
  56    support different linking features.  */
  57 enum bfd_link_hash_table_type
  58   {
  59     bfd_link_generic_hash_table,
  60     bfd_link_elf_hash_table
  61   };
  62 \f
  63 /* These are the possible types of an entry in the BFD link hash
  64    table.  */
  65
  66 enum bfd_link_hash_type
  67 {
  68   bfd_link_hash_new,            /* Symbol is new.  */
  69   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  70   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  71   bfd_link_hash_defined,        /* Symbol is defined.  */
  72   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  73   bfd_link_hash_common,         /* Symbol is common.  */
  74   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  75   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  76 };
  77
  78 enum bfd_link_common_skip_ar_symbols
  79 {
  80   bfd_link_common_skip_none,
  81   bfd_link_common_skip_text,
  82   bfd_link_common_skip_data,
  83   bfd_link_common_skip_all
  84 };
  85
  86 struct bfd_link_hash_common_entry
  87   {
  88     unsigned int alignment_power;       /* Alignment.  */
  89     asection *section;          /* Symbol section.  */
  90   };
  91
  92 /* The linking routines use a hash table which uses this structure for
  93    its elements.  */
  94
  95 struct bfd_link_hash_entry
  96 {
  97   /* Base hash table entry structure.  */
  98   struct bfd_hash_entry root;
  99
 100   /* Type of this entry.  */
 101   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 102
 103   /* Symbol is referenced in a normal object file, as distict from a LTO
 104      IR object file.  */
 105   unsigned int non_ir_ref : 1;
 106
 107   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 108      in a linker script.  */
 109   unsigned int linker_def : 1;
 110
 111   /* Symbol defined in a linker script.  */
 112   unsigned int ldscript_def : 1;
 113
 114   /* A union of information depending upon the type.  */
 115   union
 116     {
 117       /* Nothing is kept for bfd_hash_new.  */
 118       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 119       struct
 120         {
 121           /* Undefined and common symbols are kept in a linked list through
 122              this field.  This field is present in all of the union element
 123              so that we don't need to remove entries from the list when we
 124              change their type.  Removing entries would either require the
 125              list to be doubly linked, which would waste more memory, or
 126              require a traversal.  When an undefined or common symbol is
 127              created, it should be added to this list, the head of which is in
 128              the link hash table itself.  As symbols are defined, they need
 129              not be removed from the list; anything which reads the list must
 130              doublecheck the symbol type.
 131
 132              Weak symbols are not kept on this list.
 133
 134              Defined and defweak symbols use this field as a reference marker.
 135              If the field is not NULL, or this structure is the tail of the
 136              undefined symbol list, the symbol has been referenced.  If the
 137              symbol is undefined and becomes defined, this field will
 138              automatically be non-NULL since the symbol will have been on the
 139              undefined symbol list.  */
 140           struct bfd_link_hash_entry *next;
 141           /* BFD symbol was found in.  */
 142           bfd *abfd;
 143           /* For __start_<name> and __stop_<name> symbols, the first
 144              input section matching the name.  */
 145           asection *section;
 146         } undef;
 147       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 148       struct
 149         {
 150           struct bfd_link_hash_entry *next;
 151           /* Symbol section.  */
 152           asection *section;
 153           /* Symbol value.  */
 154           bfd_vma value;
 155         } def;
 156       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 157       struct
 158         {
 159           struct bfd_link_hash_entry *next;
 160           /* Real symbol.  */
 161           struct bfd_link_hash_entry *link;
 162           /* Warning message (bfd_link_hash_warning only).  */
 163           const char *warning;
 164         } i;
 165       /* bfd_link_hash_common.  */
 166       struct
 167         {
 168           struct bfd_link_hash_entry *next;
 169           /* The linker needs to know three things about common
 170              symbols: the size, the alignment, and the section in
 171              which the symbol should be placed.  We store the size
 172              here, and we allocate a small structure to hold the
 173              section and the alignment.  The alignment is stored as a
 174              power of two.  We don't store all the information
 175              directly because we don't want to increase the size of
 176              the union; this structure is a major space user in the
 177              linker.  */
 178           struct bfd_link_hash_common_entry *p;
 179           /* Common symbol size.  */
 180           bfd_size_type size;
 181         } c;
 182     } u;
 183 };
 184
 185 /* This is the link hash table.  It is a derived class of
 186    bfd_hash_table.  */
 187
 188 struct bfd_link_hash_table
 189 {
 190   /* The hash table itself.  */
 191   struct bfd_hash_table table;
 192   /* A linked list of undefined and common symbols, linked through the
 193      next field in the bfd_link_hash_entry structure.  */
 194   struct bfd_link_hash_entry *undefs;
 195   /* Entries are added to the tail of the undefs list.  */
 196   struct bfd_link_hash_entry *undefs_tail;
 197   /* Function to free the hash table on closing BFD.  */
 198   void (*hash_table_free) (bfd *);
 199   /* The type of the link hash table.  */
 200   enum bfd_link_hash_table_type type;
 201 };
 202
 203 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 204    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 205    the real symbol.  */
 206 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 207   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 208    bfd_boolean copy, bfd_boolean follow);
 209
 210 /* Look up an entry in the main linker hash table if the symbol might
 211    be wrapped.  This should only be used for references to an
 212    undefined symbol, not for definitions of a symbol.  */
 213
 214 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 215   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 216    bfd_boolean, bfd_boolean);
 217
 218 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 219    and the remainder is found in wrap_hash, return the real symbol.  */
 220
 221 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 222   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 223
 224 /* Traverse a link hash table.  */
 225 extern void bfd_link_hash_traverse
 226   (struct bfd_link_hash_table *,
 227     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 228     void *);
 229
 230 /* Add an entry to the undefs list.  */
 231 extern void bfd_link_add_undef
 232   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 233
 234 /* Remove symbols from the undefs list that don't belong there.  */
 235 extern void bfd_link_repair_undef_list
 236   (struct bfd_link_hash_table *table);
 237
 238 /* Read symbols and cache symbol pointer array in outsymbols.  */
 239 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 240
 241 /* Check the relocs in the BFD.  Called after all the input
 242    files have been loaded, and garbage collection has tagged
 243    any unneeded sections.  */
 244 extern bfd_boolean bfd_link_check_relocs (bfd *,struct bfd_link_info *);
 245
 246 struct bfd_sym_chain
 247 {
 248   struct bfd_sym_chain *next;
 249   const char *name;
 250 };
 251 \f
 252 /* How to handle unresolved symbols.
 253    There are four possibilities which are enumerated below:  */
 254 enum report_method
 255 {
 256   /* This is the initial value when then link_info structure is created.
 257      It allows the various stages of the linker to determine whether they
 258      allowed to set the value.  */
 259   RM_NOT_YET_SET = 0,
 260   RM_IGNORE,
 261   RM_GENERATE_WARNING,
 262   RM_GENERATE_ERROR
 263 };
 264
 265 typedef enum {with_flags, without_flags} flag_type;
 266
 267 /* A section flag list.  */
 268 struct flag_info_list
 269 {
 270   flag_type with;
 271   const char *name;
 272   bfd_boolean valid;
 273   struct flag_info_list *next;
 274 };
 275
 276 /* Section flag info.  */
 277 struct flag_info
 278 {
 279   flagword only_with_flags;
 280   flagword not_with_flags;
 281   struct flag_info_list *flag_list;
 282   bfd_boolean flags_initialized;
 283 };
 284
 285 struct bfd_elf_dynamic_list;
 286 struct bfd_elf_version_tree;
 287
 288 /* Types of output.  */
 289
 290 enum output_type
 291 {
 292   type_pde,
 293   type_pie,
 294   type_relocatable,
 295   type_dll,
 296 };
 297
 298 #define bfd_link_pde(info)         ((info)->type == type_pde)
 299 #define bfd_link_dll(info)         ((info)->type == type_dll)
 300 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 301 #define bfd_link_pie(info)         ((info)->type == type_pie)
 302 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 303 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 304
 305 /* This structure holds all the information needed to communicate
 306    between BFD and the linker when doing a link.  */
 307
 308 struct bfd_link_info
 309 {
 310   /* Output type.  */
 311   ENUM_BITFIELD (output_type) type : 2;
 312
 313   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 314   unsigned int symbolic: 1;
 315
 316   /* TRUE if executable should not contain copy relocs.
 317      Setting this true may result in a non-sharable text segment.  */
 318   unsigned int nocopyreloc: 1;
 319
 320   /* TRUE if BFD should export all symbols in the dynamic symbol table
 321      of an executable, rather than only those used.  */
 322   unsigned int export_dynamic: 1;
 323
 324   /* TRUE if a default symbol version should be created and used for
 325      exported symbols.  */
 326   unsigned int create_default_symver: 1;
 327
 328   /* TRUE if unreferenced sections should be removed.  */
 329   unsigned int gc_sections: 1;
 330
 331   /* TRUE if exported symbols should be kept during section gc.  */
 332   unsigned int gc_keep_exported: 1;
 333
 334   /* TRUE if every symbol should be reported back via the notice
 335      callback.  */
 336   unsigned int notice_all: 1;
 337
 338   /* TRUE if the LTO plugin is active.  */
 339   unsigned int lto_plugin_active: 1;
 340
 341   /* TRUE if global symbols in discarded sections should be stripped.  */
 342   unsigned int strip_discarded: 1;
 343
 344   /* TRUE if all data symbols should be dynamic.  */
 345   unsigned int dynamic_data: 1;
 346
 347   /* Which symbols to strip.  */
 348   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 349
 350   /* Which local symbols to discard.  */
 351   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 352
 353   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 354   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 355
 356   /* Criteria for skipping symbols when determining
 357      whether to include an object from an archive. */
 358   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 359
 360   /* What to do with unresolved symbols in an object file.
 361      When producing executables the default is GENERATE_ERROR.
 362      When producing shared libraries the default is IGNORE.  The
 363      assumption with shared libraries is that the reference will be
 364      resolved at load/execution time.  */
 365   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 366
 367   /* What to do with unresolved symbols in a shared library.
 368      The same defaults apply.  */
 369   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 370
 371   /* TRUE if shared objects should be linked directly, not shared.  */
 372   unsigned int static_link: 1;
 373
 374   /* TRUE if symbols should be retained in memory, FALSE if they
 375      should be freed and reread.  */
 376   unsigned int keep_memory: 1;
 377
 378   /* TRUE if BFD should generate relocation information in the final
 379      executable.  */
 380   unsigned int emitrelocations: 1;
 381
 382   /* TRUE if PT_GNU_RELRO segment should be created.  */
 383   unsigned int relro: 1;
 384
 385   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 386      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 387   unsigned int eh_frame_hdr_type: 2;
 388
 389   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 390   unsigned int warn_shared_textrel: 1;
 391
 392   /* TRUE if we should error when adding a DT_TEXTREL.  */
 393   unsigned int error_textrel: 1;
 394
 395   /* TRUE if .hash section should be created.  */
 396   unsigned int emit_hash: 1;
 397
 398   /* TRUE if .gnu.hash section should be created.  */
 399   unsigned int emit_gnu_hash: 1;
 400
 401   /* If TRUE reduce memory overheads, at the expense of speed. This will
 402      cause map file generation to use an O(N^2) algorithm and disable
 403      caching ELF symbol buffer.  */
 404   unsigned int reduce_memory_overheads: 1;
 405
 406   /* TRUE if the output file should be in a traditional format.  This
 407      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 408      on the output file, but may be checked when reading the input
 409      files.  */
 410   unsigned int traditional_format: 1;
 411
 412   /* TRUE if non-PLT relocs should be merged into one reloc section
 413      and sorted so that relocs against the same symbol come together.  */
 414   unsigned int combreloc: 1;
 415
 416   /* TRUE if a default symbol version should be created and used for
 417      imported symbols.  */
 418   unsigned int default_imported_symver: 1;
 419
 420   /* TRUE if the new ELF dynamic tags are enabled. */
 421   unsigned int new_dtags: 1;
 422
 423   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 424      linker created sections, TRUE if it should be omitted.  */
 425   unsigned int no_ld_generated_unwind_info: 1;
 426
 427   /* TRUE if BFD should generate a "task linked" object file,
 428      similar to relocatable but also with globals converted to
 429      statics.  */
 430   unsigned int task_link: 1;
 431
 432   /* TRUE if ok to have multiple definition.  */
 433   unsigned int allow_multiple_definition: 1;
 434
 435   /* TRUE if ok to have version with no definition.  */
 436   unsigned int allow_undefined_version: 1;
 437
 438   /* TRUE if some symbols have to be dynamic, controlled by
 439      --dynamic-list command line options.  */
 440   unsigned int dynamic: 1;
 441
 442   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 443      flags.  */
 444   unsigned int execstack: 1;
 445
 446   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 447      flags.  */
 448   unsigned int noexecstack: 1;
 449
 450   /* TRUE if we want to produced optimized output files.  This might
 451      need much more time and therefore must be explicitly selected.  */
 452   unsigned int optimize: 1;
 453
 454   /* TRUE if user should be informed of removed unreferenced sections.  */
 455   unsigned int print_gc_sections: 1;
 456
 457   /* TRUE if we should warn alternate ELF machine code.  */
 458   unsigned int warn_alternate_em: 1;
 459
 460   /* TRUE if the linker script contained an explicit PHDRS command.  */
 461   unsigned int user_phdrs: 1;
 462
 463   /* TRUE if we should check relocations after all input files have
 464      been opened.  */
 465   unsigned int check_relocs_after_open_input: 1;
 466
 467   /* TRUE if BND prefix in PLT entries is always generated.  */
 468   unsigned int bndplt: 1;
 469
 470   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 471   unsigned int nointerp: 1;
 472
 473   /* TRUE if we shouldn't check relocation overflow.  */
 474   unsigned int no_reloc_overflow_check: 1;
 475
 476   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
 477   unsigned int call_nop_as_suffix : 1;
 478
 479   /* The 1-byte NOP for x86 call instruction.  */
 480   char call_nop_byte;
 481
 482   /* Char that may appear as the first char of a symbol, but should be
 483      skipped (like symbol_leading_char) when looking up symbols in
 484      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 485   char wrap_char;
 486
 487   /* Separator between archive and filename in linker script filespecs.  */
 488   char path_separator;
 489
 490   /* Compress DWARF debug sections.  */
 491   enum compressed_debug_section_type compress_debug;
 492
 493   /* Default stack size.  Zero means default (often zero itself), -1
 494      means explicitly zero-sized.  */
 495   bfd_signed_vma stacksize;
 496
 497   /* Enable or disable target specific optimizations.
 498
 499      Not all targets have optimizations to enable.
 500
 501      Normally these optimizations are disabled by default but some targets
 502      prefer to enable them by default.  So this field is a tri-state variable.
 503      The values are:
 504
 505      zero: Enable the optimizations (either from --relax being specified on
 506        the command line or the backend's before_allocation emulation function.
 507
 508      positive: The user has requested that these optimizations be disabled.
 509        (Via the --no-relax command line option).
 510
 511      negative: The optimizations are disabled.  (Set when initializing the
 512        args_type structure in ldmain.c:main.  */
 513   signed int disable_target_specific_optimizations;
 514
 515   /* Function callbacks.  */
 516   const struct bfd_link_callbacks *callbacks;
 517
 518   /* Hash table handled by BFD.  */
 519   struct bfd_link_hash_table *hash;
 520
 521   /* Hash table of symbols to keep.  This is NULL unless strip is
 522      strip_some.  */
 523   struct bfd_hash_table *keep_hash;
 524
 525   /* Hash table of symbols to report back via the notice callback.  If
 526      this is NULL, and notice_all is FALSE, then no symbols are
 527      reported back.  */
 528   struct bfd_hash_table *notice_hash;
 529
 530   /* Hash table of symbols which are being wrapped (the --wrap linker
 531      option).  If this is NULL, no symbols are being wrapped.  */
 532   struct bfd_hash_table *wrap_hash;
 533
 534   /* Hash table of symbols which may be left unresolved during
 535      a link.  If this is NULL, no symbols can be left unresolved.  */
 536   struct bfd_hash_table *ignore_hash;
 537
 538   /* The output BFD.  */
 539   bfd *output_bfd;
 540
 541   /* The import library generated.  */
 542   bfd *out_implib_bfd;
 543
 544   /* The list of input BFD's involved in the link.  These are chained
 545      together via the link.next field.  */
 546   bfd *input_bfds;
 547   bfd **input_bfds_tail;
 548
 549   /* If a symbol should be created for each input BFD, this is section
 550      where those symbols should be placed.  It must be a section in
 551      the output BFD.  It may be NULL, in which case no such symbols
 552      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 553      linker command language.  */
 554   asection *create_object_symbols_section;
 555
 556   /* List of global symbol names that are starting points for marking
 557      sections against garbage collection.  */
 558   struct bfd_sym_chain *gc_sym_list;
 559
 560   /* If a base output file is wanted, then this points to it */
 561   void *base_file;
 562
 563   /* The function to call when the executable or shared object is
 564      loaded.  */
 565   const char *init_function;
 566
 567   /* The function to call when the executable or shared object is
 568      unloaded.  */
 569   const char *fini_function;
 570
 571   /* Number of relaxation passes.  Usually only one relaxation pass
 572      is needed.  But a backend can have as many relaxation passes as
 573      necessary.  During bfd_relax_section call, it is set to the
 574      current pass, starting from 0.  */
 575   int relax_pass;
 576
 577   /* Number of relaxation trips.  This number is incremented every
 578      time the relaxation pass is restarted due to a previous
 579      relaxation returning true in *AGAIN.  */
 580   int relax_trip;
 581
 582   /* > 0 to treat protected data defined in the shared library as
 583      reference external.  0 to treat it as internal.  -1 to let
 584      backend to decide.  */
 585   int extern_protected_data;
 586
 587   /* > 0 to treat undefined weak symbol in the executable as dynamic,
 588      requiring dynamic relocation.  */
 589   int dynamic_undefined_weak;
 590
 591   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 592      should be generated/linked against.  Set to 1 if this feature
 593      is explicitly requested by the user, -1 if enabled by default.  */
 594   int pei386_auto_import;
 595
 596   /* Non-zero if runtime relocs for DATA items with non-zero addends
 597      in pei386 DLLs should be generated.  Set to 1 if this feature
 598      is explicitly requested by the user, -1 if enabled by default.  */
 599   int pei386_runtime_pseudo_reloc;
 600
 601   /* How many spare .dynamic DT_NULL entries should be added?  */
 602   unsigned int spare_dynamic_tags;
 603
 604   /* May be used to set DT_FLAGS for ELF. */
 605   bfd_vma flags;
 606
 607   /* May be used to set DT_FLAGS_1 for ELF. */
 608   bfd_vma flags_1;
 609
 610   /* Start and end of RELRO region.  */
 611   bfd_vma relro_start, relro_end;
 612
 613   /* List of symbols should be dynamic.  */
 614   struct bfd_elf_dynamic_list *dynamic_list;
 615
 616   /* The version information.  */
 617   struct bfd_elf_version_tree *version_info;
 618 };
 619
 620 /* This structures holds a set of callback functions.  These are called
 621    by the BFD linker routines.  */
 622
 623 struct bfd_link_callbacks
 624 {
 625   /* A function which is called when an object is added from an
 626      archive.  ABFD is the archive element being added.  NAME is the
 627      name of the symbol which caused the archive element to be pulled
 628      in.  This function may set *SUBSBFD to point to an alternative
 629      BFD from which symbols should in fact be added in place of the
 630      original BFD's symbols.  Returns TRUE if the object should be
 631      added, FALSE if it should be skipped.  */
 632   bfd_boolean (*add_archive_element)
 633     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 634   /* A function which is called when a symbol is found with multiple
 635      definitions.  H is the symbol which is defined multiple times.
 636      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 637      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 638   void (*multiple_definition)
 639     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 640      bfd *nbfd, asection *nsec, bfd_vma nval);
 641   /* A function which is called when a common symbol is defined
 642      multiple times.  H is the symbol appearing multiple times.
 643      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 644      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 645      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 646      is the size of the new symbol.  */
 647   void (*multiple_common)
 648     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 649      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 650   /* A function which is called to add a symbol to a set.  ENTRY is
 651      the link hash table entry for the set itself (e.g.,
 652      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 653      the set when generating a relocatable file, and is also used to
 654      get the size of the entry when generating an executable file.
 655      ABFD, SEC and VALUE identify the value to add to the set.  */
 656   void (*add_to_set)
 657     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 658      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 659   /* A function which is called when the name of a g++ constructor or
 660      destructor is found.  This is only called by some object file
 661      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 662      destructor.  This will use BFD_RELOC_CTOR when generating a
 663      relocatable file.  NAME is the name of the symbol found.  ABFD,
 664      SECTION and VALUE are the value of the symbol.  */
 665   void (*constructor)
 666     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 667      bfd *abfd, asection *sec, bfd_vma value);
 668   /* A function which is called to issue a linker warning.  For
 669      example, this is called when there is a reference to a warning
 670      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 671      of the symbol which triggered the warning; it may be NULL if
 672      there is none.  ABFD, SECTION and ADDRESS identify the location
 673      which trigerred the warning; either ABFD or SECTION or both may
 674      be NULL if the location is not known.  */
 675   void (*warning)
 676     (struct bfd_link_info *, const char *warning, const char *symbol,
 677      bfd *abfd, asection *section, bfd_vma address);
 678   /* A function which is called when a relocation is attempted against
 679      an undefined symbol.  NAME is the symbol which is undefined.
 680      ABFD, SECTION and ADDRESS identify the location from which the
 681      reference is made. IS_FATAL indicates whether an undefined symbol is
 682      a fatal error or not. In some cases SECTION may be NULL.  */
 683   void (*undefined_symbol)
 684     (struct bfd_link_info *, const char *name, bfd *abfd,
 685      asection *section, bfd_vma address, bfd_boolean is_fatal);
 686   /* A function which is called when a reloc overflow occurs. ENTRY is
 687      the link hash table entry for the symbol the reloc is against.
 688      NAME is the name of the local symbol or section the reloc is
 689      against, RELOC_NAME is the name of the relocation, and ADDEND is
 690      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 691      location at which the overflow occurs; if this is the result of a
 692      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 693      ABFD will be NULL.  */
 694   void (*reloc_overflow)
 695     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 696      const char *name, const char *reloc_name, bfd_vma addend,
 697      bfd *abfd, asection *section, bfd_vma address);
 698   /* A function which is called when a dangerous reloc is performed.
 699      MESSAGE is an appropriate message.
 700      ABFD, SECTION and ADDRESS identify the location at which the
 701      problem occurred; if this is the result of a
 702      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 703      ABFD will be NULL.  */
 704   void (*reloc_dangerous)
 705     (struct bfd_link_info *, const char *message,
 706      bfd *abfd, asection *section, bfd_vma address);
 707   /* A function which is called when a reloc is found to be attached
 708      to a symbol which is not being written out.  NAME is the name of
 709      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 710      the reloc; if this is the result of a
 711      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 712      ABFD will be NULL.  */
 713   void (*unattached_reloc)
 714     (struct bfd_link_info *, const char *name,
 715      bfd *abfd, asection *section, bfd_vma address);
 716   /* A function which is called when a symbol in notice_hash is
 717      defined or referenced.  H is the symbol, INH the indirect symbol
 718      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 719      the symbol.  If SECTION is bfd_und_section, this is a reference.
 720      FLAGS are the symbol BSF_* flags.  */
 721   bfd_boolean (*notice)
 722     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 723      struct bfd_link_hash_entry *inh,
 724      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 725   /* Error or warning link info message.  */
 726   void (*einfo)
 727     (const char *fmt, ...);
 728   /* General link info message.  */
 729   void (*info)
 730     (const char *fmt, ...);
 731   /* Message to be printed in linker map file.  */
 732   void (*minfo)
 733     (const char *fmt, ...);
 734   /* This callback provides a chance for users of the BFD library to
 735      override its decision about whether to place two adjacent sections
 736      into the same segment.  */
 737   bfd_boolean (*override_segment_assignment)
 738     (struct bfd_link_info *, bfd * abfd,
 739      asection * current_section, asection * previous_section,
 740      bfd_boolean new_segment);
 741 };
 742 \f
 743 /* The linker builds link_order structures which tell the code how to
 744    include input data in the output file.  */
 745
 746 /* These are the types of link_order structures.  */
 747
 748 enum bfd_link_order_type
 749 {
 750   bfd_undefined_link_order,     /* Undefined.  */
 751   bfd_indirect_link_order,      /* Built from a section.  */
 752   bfd_data_link_order,          /* Set to explicit data.  */
 753   bfd_section_reloc_link_order, /* Relocate against a section.  */
 754   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 755 };
 756
 757 /* This is the link_order structure itself.  These form a chain
 758    attached to the output section whose contents they are describing.  */
 759
 760 struct bfd_link_order
 761 {
 762   /* Next link_order in chain.  */
 763   struct bfd_link_order *next;
 764   /* Type of link_order.  */
 765   enum bfd_link_order_type type;
 766   /* Offset within output section.  */
 767   bfd_vma offset;
 768   /* Size within output section.  */
 769   bfd_size_type size;
 770   /* Type specific information.  */
 771   union
 772     {
 773       struct
 774         {
 775           /* Section to include.  If this is used, then
 776              section->output_section must be the section the
 777              link_order is attached to, section->output_offset must
 778              equal the link_order offset field, and section->size
 779              must equal the link_order size field.  Maybe these
 780              restrictions should be relaxed someday.  */
 781           asection *section;
 782         } indirect;
 783       struct
 784         {
 785           /* Size of contents, or zero when contents should be filled by
 786              the architecture-dependent fill function.
 787              A non-zero value allows filling of the output section
 788              with an arbitrary repeated pattern.  */
 789           unsigned int size;
 790           /* Data to put into file.  */
 791           bfd_byte *contents;
 792         } data;
 793       struct
 794         {
 795           /* Description of reloc to generate.  Used for
 796              bfd_section_reloc_link_order and
 797              bfd_symbol_reloc_link_order.  */
 798           struct bfd_link_order_reloc *p;
 799         } reloc;
 800     } u;
 801 };
 802
 803 /* A linker order of type bfd_section_reloc_link_order or
 804    bfd_symbol_reloc_link_order means to create a reloc against a
 805    section or symbol, respectively.  This is used to implement -Ur to
 806    generate relocs for the constructor tables.  The
 807    bfd_link_order_reloc structure describes the reloc that BFD should
 808    create.  It is similar to a arelent, but I didn't use arelent
 809    because the linker does not know anything about most symbols, and
 810    any asymbol structure it creates will be partially meaningless.
 811    This information could logically be in the bfd_link_order struct,
 812    but I didn't want to waste the space since these types of relocs
 813    are relatively rare.  */
 814
 815 struct bfd_link_order_reloc
 816 {
 817   /* Reloc type.  */
 818   bfd_reloc_code_real_type reloc;
 819
 820   union
 821     {
 822       /* For type bfd_section_reloc_link_order, this is the section
 823          the reloc should be against.  This must be a section in the
 824          output BFD, not any of the input BFDs.  */
 825       asection *section;
 826       /* For type bfd_symbol_reloc_link_order, this is the name of the
 827          symbol the reloc should be against.  */
 828       const char *name;
 829     } u;
 830
 831   /* Addend to use.  The object file should contain zero.  The BFD
 832      backend is responsible for filling in the contents of the object
 833      file correctly.  For some object file formats (e.g., COFF) the
 834      addend must be stored into in the object file, and for some
 835      (e.g., SPARC a.out) it is kept in the reloc.  */
 836   bfd_vma addend;
 837 };
 838
 839 /* Allocate a new link_order for a section.  */
 840 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 841
 842 /* These structures are used to describe version information for the
 843    ELF linker.  These structures could be manipulated entirely inside
 844    BFD, but it would be a pain.  Instead, the regular linker sets up
 845    these structures, and then passes them into BFD.  */
 846
 847 /* Glob pattern for a version.  */
 848
 849 struct bfd_elf_version_expr
 850 {
 851   /* Next glob pattern for this version.  */
 852   struct bfd_elf_version_expr *next;
 853   /* Glob pattern.  */
 854   const char *pattern;
 855   /* Set if pattern is not a glob.  */
 856   unsigned int literal : 1;
 857   /* Defined by ".symver".  */
 858   unsigned int symver : 1;
 859   /* Defined by version script.  */
 860   unsigned int script : 1;
 861   /* Pattern type.  */
 862 #define BFD_ELF_VERSION_C_TYPE          1
 863 #define BFD_ELF_VERSION_CXX_TYPE        2
 864 #define BFD_ELF_VERSION_JAVA_TYPE       4
 865   unsigned int mask : 3;
 866 };
 867
 868 struct bfd_elf_version_expr_head
 869 {
 870   /* List of all patterns, both wildcards and non-wildcards.  */
 871   struct bfd_elf_version_expr *list;
 872   /* Hash table for non-wildcards.  */
 873   void *htab;
 874   /* Remaining patterns.  */
 875   struct bfd_elf_version_expr *remaining;
 876   /* What kind of pattern types are present in list (bitmask).  */
 877   unsigned int mask;
 878 };
 879
 880 /* Version dependencies.  */
 881
 882 struct bfd_elf_version_deps
 883 {
 884   /* Next dependency for this version.  */
 885   struct bfd_elf_version_deps *next;
 886   /* The version which this version depends upon.  */
 887   struct bfd_elf_version_tree *version_needed;
 888 };
 889
 890 /* A node in the version tree.  */
 891
 892 struct bfd_elf_version_tree
 893 {
 894   /* Next version.  */
 895   struct bfd_elf_version_tree *next;
 896   /* Name of this version.  */
 897   const char *name;
 898   /* Version number.  */
 899   unsigned int vernum;
 900   /* Regular expressions for global symbols in this version.  */
 901   struct bfd_elf_version_expr_head globals;
 902   /* Regular expressions for local symbols in this version.  */
 903   struct bfd_elf_version_expr_head locals;
 904   /* List of versions which this version depends upon.  */
 905   struct bfd_elf_version_deps *deps;
 906   /* Index of the version name.  This is used within BFD.  */
 907   unsigned int name_indx;
 908   /* Whether this version tree was used.  This is used within BFD.  */
 909   int used;
 910   /* Matching hook.  */
 911   struct bfd_elf_version_expr *(*match)
 912     (struct bfd_elf_version_expr_head *head,
 913      struct bfd_elf_version_expr *prev, const char *sym);
 914 };
 915
 916 struct bfd_elf_dynamic_list
 917 {
 918   struct bfd_elf_version_expr_head head;
 919   struct bfd_elf_version_expr *(*match)
 920     (struct bfd_elf_version_expr_head *head,
 921      struct bfd_elf_version_expr *prev, const char *sym);
 922 };
 923
 924 #endif