include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2021 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 enum notice_asneeded_action {
  46   notice_as_needed,
  47   notice_not_needed,
  48   notice_needed
  49 };
  50
  51 /* Whether to generate ELF common symbols with the STT_COMMON type
  52    during a relocatable link.  */
  53 enum bfd_link_elf_stt_common
  54 {
  55   unchanged,
  56   elf_stt_common,
  57   no_elf_stt_common
  58 };
  59
  60 /* Describes the type of hash table entry structure being used.
  61    Different hash table structure have different fields and so
  62    support different linking features.  */
  63 enum bfd_link_hash_table_type
  64   {
  65     bfd_link_generic_hash_table,
  66     bfd_link_elf_hash_table
  67   };
  68 \f
  69 /* These are the possible types of an entry in the BFD link hash
  70    table.  */
  71
  72 enum bfd_link_hash_type
  73 {
  74   bfd_link_hash_new,            /* Symbol is new.  */
  75   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  76   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  77   bfd_link_hash_defined,        /* Symbol is defined.  */
  78   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  79   bfd_link_hash_common,         /* Symbol is common.  */
  80   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  81   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  82 };
  83
  84 enum bfd_link_common_skip_ar_symbols
  85 {
  86   bfd_link_common_skip_none,
  87   bfd_link_common_skip_text,
  88   bfd_link_common_skip_data,
  89   bfd_link_common_skip_all
  90 };
  91
  92 struct bfd_link_hash_common_entry
  93   {
  94     unsigned int alignment_power;       /* Alignment.  */
  95     asection *section;          /* Symbol section.  */
  96   };
  97
  98 /* The linking routines use a hash table which uses this structure for
  99    its elements.  */
 100
 101 struct bfd_link_hash_entry
 102 {
 103   /* Base hash table entry structure.  */
 104   struct bfd_hash_entry root;
 105
 106   /* Type of this entry.  */
 107   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 108
 109   /* Symbol is referenced in a normal regular object file,
 110      as distinct from a LTO IR object file.  */
 111   unsigned int non_ir_ref_regular : 1;
 112
 113   /* Symbol is referenced in a normal dynamic object file,
 114      as distinct from a LTO IR object file.  */
 115   unsigned int non_ir_ref_dynamic : 1;
 116
 117   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 118      in a linker script.  */
 119   unsigned int linker_def : 1;
 120
 121   /* Symbol defined in a linker script.  */
 122   unsigned int ldscript_def : 1;
 123
 124   /* Symbol will be converted from absolute to section-relative.  Set for
 125      symbols defined by a script from "dot" (also SEGMENT_START or ORIGIN)
 126      outside of an output section statement.  */
 127   unsigned int rel_from_abs : 1;
 128
 129   /* A union of information depending upon the type.  */
 130   union
 131     {
 132       /* Nothing is kept for bfd_hash_new.  */
 133       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 134       struct
 135         {
 136           /* Undefined and common symbols are kept in a linked list through
 137              this field.  This field is present in all of the union element
 138              so that we don't need to remove entries from the list when we
 139              change their type.  Removing entries would either require the
 140              list to be doubly linked, which would waste more memory, or
 141              require a traversal.  When an undefined or common symbol is
 142              created, it should be added to this list, the head of which is in
 143              the link hash table itself.  As symbols are defined, they need
 144              not be removed from the list; anything which reads the list must
 145              doublecheck the symbol type.
 146
 147              Weak symbols are not kept on this list.
 148
 149              Defined and defweak symbols use this field as a reference marker.
 150              If the field is not NULL, or this structure is the tail of the
 151              undefined symbol list, the symbol has been referenced.  If the
 152              symbol is undefined and becomes defined, this field will
 153              automatically be non-NULL since the symbol will have been on the
 154              undefined symbol list.  */
 155           struct bfd_link_hash_entry *next;
 156           /* BFD symbol was found in.  */
 157           bfd *abfd;
 158         } undef;
 159       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 160       struct
 161         {
 162           struct bfd_link_hash_entry *next;
 163           /* Symbol section.  */
 164           asection *section;
 165           /* Symbol value.  */
 166           bfd_vma value;
 167         } def;
 168       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 169       struct
 170         {
 171           struct bfd_link_hash_entry *next;
 172           /* Real symbol.  */
 173           struct bfd_link_hash_entry *link;
 174           /* Warning message (bfd_link_hash_warning only).  */
 175           const char *warning;
 176         } i;
 177       /* bfd_link_hash_common.  */
 178       struct
 179         {
 180           struct bfd_link_hash_entry *next;
 181           /* The linker needs to know three things about common
 182              symbols: the size, the alignment, and the section in
 183              which the symbol should be placed.  We store the size
 184              here, and we allocate a small structure to hold the
 185              section and the alignment.  The alignment is stored as a
 186              power of two.  We don't store all the information
 187              directly because we don't want to increase the size of
 188              the union; this structure is a major space user in the
 189              linker.  */
 190           struct bfd_link_hash_common_entry *p;
 191           /* Common symbol size.  */
 192           bfd_size_type size;
 193         } c;
 194     } u;
 195 };
 196
 197 /* This is the link hash table.  It is a derived class of
 198    bfd_hash_table.  */
 199
 200 struct bfd_link_hash_table
 201 {
 202   /* The hash table itself.  */
 203   struct bfd_hash_table table;
 204   /* A linked list of undefined and common symbols, linked through the
 205      next field in the bfd_link_hash_entry structure.  */
 206   struct bfd_link_hash_entry *undefs;
 207   /* Entries are added to the tail of the undefs list.  */
 208   struct bfd_link_hash_entry *undefs_tail;
 209   /* Function to free the hash table on closing BFD.  */
 210   void (*hash_table_free) (bfd *);
 211   /* The type of the link hash table.  */
 212   enum bfd_link_hash_table_type type;
 213 };
 214
 215 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 216    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 217    the real symbol.  */
 218 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 219   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 220    bfd_boolean copy, bfd_boolean follow);
 221
 222 /* Look up an entry in the main linker hash table if the symbol might
 223    be wrapped.  This should only be used for references to an
 224    undefined symbol, not for definitions of a symbol.  */
 225
 226 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 227   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 228    bfd_boolean, bfd_boolean);
 229
 230 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 231    and the remainder is found in wrap_hash, return the real symbol.  */
 232
 233 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 234   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 235
 236 /* Traverse a link hash table.  */
 237 extern void bfd_link_hash_traverse
 238   (struct bfd_link_hash_table *,
 239     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 240     void *);
 241
 242 /* Add an entry to the undefs list.  */
 243 extern void bfd_link_add_undef
 244   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 245
 246 /* Remove symbols from the undefs list that don't belong there.  */
 247 extern void bfd_link_repair_undef_list
 248   (struct bfd_link_hash_table *table);
 249
 250 /* Read symbols and cache symbol pointer array in outsymbols.  */
 251 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 252
 253 /* Check the relocs in the BFD.  Called after all the input
 254    files have been loaded, and garbage collection has tagged
 255    any unneeded sections.  */
 256 extern bfd_boolean bfd_link_check_relocs (bfd *,struct bfd_link_info *);
 257
 258 struct bfd_sym_chain
 259 {
 260   struct bfd_sym_chain *next;
 261   const char *name;
 262 };
 263 \f
 264 /* How to handle unresolved symbols.
 265    There are four possibilities which are enumerated below:  */
 266 enum report_method
 267 {
 268   /* This is the initial value when then link_info structure is created.
 269      It allows the various stages of the linker to determine whether they
 270      allowed to set the value.  */
 271   RM_NOT_YET_SET = 0,
 272   RM_IGNORE,
 273   RM_DIAGNOSE,
 274 };
 275
 276 /* How to handle DT_TEXTREL.  */
 277
 278 enum textrel_check_method
 279 {
 280   textrel_check_none,
 281   textrel_check_warning,
 282   textrel_check_error
 283 };
 284
 285 #define bfd_link_textrel_check(info) \
 286   (info->textrel_check != textrel_check_none)
 287
 288 typedef enum {with_flags, without_flags} flag_type;
 289
 290 /* A section flag list.  */
 291 struct flag_info_list
 292 {
 293   flag_type with;
 294   const char *name;
 295   bfd_boolean valid;
 296   struct flag_info_list *next;
 297 };
 298
 299 /* Section flag info.  */
 300 struct flag_info
 301 {
 302   flagword only_with_flags;
 303   flagword not_with_flags;
 304   struct flag_info_list *flag_list;
 305   bfd_boolean flags_initialized;
 306 };
 307
 308 struct bfd_elf_dynamic_list;
 309 struct bfd_elf_version_tree;
 310
 311 /* Types of output.  */
 312
 313 enum output_type
 314 {
 315   type_pde,
 316   type_pie,
 317   type_relocatable,
 318   type_dll,
 319 };
 320
 321 #define bfd_link_pde(info)         ((info)->type == type_pde)
 322 #define bfd_link_dll(info)         ((info)->type == type_dll)
 323 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 324 #define bfd_link_pie(info)         ((info)->type == type_pie)
 325 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 326 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 327
 328 /* This structure holds all the information needed to communicate
 329    between BFD and the linker when doing a link.  */
 330
 331 struct bfd_link_info
 332 {
 333   /* Output type.  */
 334   ENUM_BITFIELD (output_type) type : 2;
 335
 336   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 337   unsigned int symbolic: 1;
 338
 339   /* TRUE if executable should not contain copy relocs.
 340      Setting this true may result in a non-sharable text segment.  */
 341   unsigned int nocopyreloc: 1;
 342
 343   /* TRUE if BFD should export all symbols in the dynamic symbol table
 344      of an executable, rather than only those used.  */
 345   unsigned int export_dynamic: 1;
 346
 347   /* TRUE if a default symbol version should be created and used for
 348      exported symbols.  */
 349   unsigned int create_default_symver: 1;
 350
 351   /* TRUE if unreferenced sections should be removed.  */
 352   unsigned int gc_sections: 1;
 353
 354   /* TRUE if exported symbols should be kept during section gc.  */
 355   unsigned int gc_keep_exported: 1;
 356
 357   /* TRUE if every symbol should be reported back via the notice
 358      callback.  */
 359   unsigned int notice_all: 1;
 360
 361   /* TRUE if the LTO plugin is active.  */
 362   unsigned int lto_plugin_active: 1;
 363
 364   /* TRUE if all LTO IR symbols have been read.  */
 365   unsigned int lto_all_symbols_read : 1;
 366
 367   /* TRUE if global symbols in discarded sections should be stripped.  */
 368   unsigned int strip_discarded: 1;
 369
 370   /* TRUE if all data symbols should be dynamic.  */
 371   unsigned int dynamic_data: 1;
 372
 373   /* TRUE if section groups should be resolved.  */
 374   unsigned int resolve_section_groups: 1;
 375
 376   /* Set if output file is big-endian, or if that is unknown, from
 377      the command line or first input file endianness.  */
 378   unsigned int big_endian : 1;
 379
 380   /* Which symbols to strip.  */
 381   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 382
 383   /* Which local symbols to discard.  */
 384   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 385
 386   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 387   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 388
 389   /* Criteria for skipping symbols when determining
 390      whether to include an object from an archive.  */
 391   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 392
 393   /* What to do with unresolved symbols in an object file.
 394      When producing executables the default is GENERATE_ERROR.
 395      When producing shared libraries the default is IGNORE.  The
 396      assumption with shared libraries is that the reference will be
 397      resolved at load/execution time.  */
 398   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 399
 400   /* What to do with unresolved symbols in a shared library.
 401      The same defaults apply.  */
 402   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 403
 404   /* TRUE if unresolved symbols are to be warned, rather than errored.  */
 405   unsigned int warn_unresolved_syms: 1;
 406
 407   /* TRUE if shared objects should be linked directly, not shared.  */
 408   unsigned int static_link: 1;
 409
 410   /* TRUE if symbols should be retained in memory, FALSE if they
 411      should be freed and reread.  */
 412   unsigned int keep_memory: 1;
 413
 414   /* TRUE if BFD should generate relocation information in the final
 415      executable.  */
 416   unsigned int emitrelocations: 1;
 417
 418   /* TRUE if PT_GNU_RELRO segment should be created.  */
 419   unsigned int relro: 1;
 420
 421   /* TRUE if separate code segment should be created.  */
 422   unsigned int separate_code: 1;
 423
 424   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 425      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 426   unsigned int eh_frame_hdr_type: 2;
 427
 428   /* What to do with DT_TEXTREL in output.  */
 429   ENUM_BITFIELD (textrel_check_method) textrel_check: 2;
 430
 431   /* TRUE if .hash section should be created.  */
 432   unsigned int emit_hash: 1;
 433
 434   /* TRUE if .gnu.hash section should be created.  */
 435   unsigned int emit_gnu_hash: 1;
 436
 437   /* If TRUE reduce memory overheads, at the expense of speed. This will
 438      cause map file generation to use an O(N^2) algorithm and disable
 439      caching ELF symbol buffer.  */
 440   unsigned int reduce_memory_overheads: 1;
 441
 442   /* TRUE if the output file should be in a traditional format.  This
 443      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 444      on the output file, but may be checked when reading the input
 445      files.  */
 446   unsigned int traditional_format: 1;
 447
 448   /* TRUE if non-PLT relocs should be merged into one reloc section
 449      and sorted so that relocs against the same symbol come together.  */
 450   unsigned int combreloc: 1;
 451
 452   /* TRUE if a default symbol version should be created and used for
 453      imported symbols.  */
 454   unsigned int default_imported_symver: 1;
 455
 456   /* TRUE if the new ELF dynamic tags are enabled. */
 457   unsigned int new_dtags: 1;
 458
 459   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 460      linker created sections, TRUE if it should be omitted.  */
 461   unsigned int no_ld_generated_unwind_info: 1;
 462
 463   /* TRUE if BFD should generate a "task linked" object file,
 464      similar to relocatable but also with globals converted to
 465      statics.  */
 466   unsigned int task_link: 1;
 467
 468   /* TRUE if ok to have multiple definitions, without warning.  */
 469   unsigned int allow_multiple_definition: 1;
 470
 471   /* TRUE if multiple definition of absolute symbols (eg. from -R) should
 472      be reported.  */
 473   unsigned int prohibit_multiple_definition_absolute: 1;
 474
 475   /* TRUE if multiple definitions should only warn.  */
 476   unsigned int warn_multiple_definition: 1;
 477
 478   /* TRUE if ok to have version with no definition.  */
 479   unsigned int allow_undefined_version: 1;
 480
 481   /* TRUE if some symbols have to be dynamic, controlled by
 482      --dynamic-list command line options.  */
 483   unsigned int dynamic: 1;
 484
 485   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 486      flags.  */
 487   unsigned int execstack: 1;
 488
 489   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 490      flags.  */
 491   unsigned int noexecstack: 1;
 492
 493   /* TRUE if we want to produced optimized output files.  This might
 494      need much more time and therefore must be explicitly selected.  */
 495   unsigned int optimize: 1;
 496
 497   /* TRUE if user should be informed of removed unreferenced sections.  */
 498   unsigned int print_gc_sections: 1;
 499
 500   /* TRUE if we should warn alternate ELF machine code.  */
 501   unsigned int warn_alternate_em: 1;
 502
 503   /* TRUE if the linker script contained an explicit PHDRS command.  */
 504   unsigned int user_phdrs: 1;
 505
 506   /* TRUE if program headers ought to be loaded.  */
 507   unsigned int load_phdrs: 1;
 508
 509   /* TRUE if we should check relocations after all input files have
 510      been opened.  */
 511   unsigned int check_relocs_after_open_input: 1;
 512
 513   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 514   unsigned int nointerp: 1;
 515
 516   /* TRUE if common symbols should be treated as undefined.  */
 517   unsigned int inhibit_common_definition : 1;
 518
 519   /* TRUE if "-Map map" is passed to linker.  */
 520   unsigned int has_map_file : 1;
 521
 522   /* TRUE if "--enable-non-contiguous-regions" is passed to the
 523      linker.  */
 524   unsigned int non_contiguous_regions : 1;
 525
 526   /* TRUE if "--enable-non-contiguous-regions-warnings" is passed to
 527      the linker.  */
 528   unsigned int non_contiguous_regions_warnings : 1;
 529
 530   /* TRUE if all symbol names should be unique.  */
 531   unsigned int unique_symbol : 1;
 532
 533   /* Char that may appear as the first char of a symbol, but should be
 534      skipped (like symbol_leading_char) when looking up symbols in
 535      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 536   char wrap_char;
 537
 538   /* Separator between archive and filename in linker script filespecs.  */
 539   char path_separator;
 540
 541   /* Compress DWARF debug sections.  */
 542   enum compressed_debug_section_type compress_debug;
 543
 544   /* Default stack size.  Zero means default (often zero itself), -1
 545      means explicitly zero-sized.  */
 546   bfd_signed_vma stacksize;
 547
 548   /* Enable or disable target specific optimizations.
 549
 550      Not all targets have optimizations to enable.
 551
 552      Normally these optimizations are disabled by default but some targets
 553      prefer to enable them by default.  So this field is a tri-state variable.
 554      The values are:
 555
 556      zero: Enable the optimizations (either from --relax being specified on
 557        the command line or the backend's before_allocation emulation function.
 558
 559      positive: The user has requested that these optimizations be disabled.
 560        (Via the --no-relax command line option).
 561
 562      negative: The optimizations are disabled.  (Set when initializing the
 563        args_type structure in ldmain.c:main.  */
 564   signed int disable_target_specific_optimizations;
 565
 566   /* Function callbacks.  */
 567   const struct bfd_link_callbacks *callbacks;
 568
 569   /* Hash table handled by BFD.  */
 570   struct bfd_link_hash_table *hash;
 571
 572   /* Hash table of symbols to keep.  This is NULL unless strip is
 573      strip_some.  */
 574   struct bfd_hash_table *keep_hash;
 575
 576   /* Hash table of symbols to report back via the notice callback.  If
 577      this is NULL, and notice_all is FALSE, then no symbols are
 578      reported back.  */
 579   struct bfd_hash_table *notice_hash;
 580
 581   /* Hash table of symbols which are being wrapped (the --wrap linker
 582      option).  If this is NULL, no symbols are being wrapped.  */
 583   struct bfd_hash_table *wrap_hash;
 584
 585   /* Hash table of symbols which may be left unresolved during
 586      a link.  If this is NULL, no symbols can be left unresolved.  */
 587   struct bfd_hash_table *ignore_hash;
 588
 589   /* The output BFD.  */
 590   bfd *output_bfd;
 591
 592   /* The import library generated.  */
 593   bfd *out_implib_bfd;
 594
 595   /* The list of input BFD's involved in the link.  These are chained
 596      together via the link.next field.  */
 597   bfd *input_bfds;
 598   bfd **input_bfds_tail;
 599
 600   /* If a symbol should be created for each input BFD, this is section
 601      where those symbols should be placed.  It must be a section in
 602      the output BFD.  It may be NULL, in which case no such symbols
 603      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 604      linker command language.  */
 605   asection *create_object_symbols_section;
 606
 607   /* List of global symbol names that are starting points for marking
 608      sections against garbage collection.  */
 609   struct bfd_sym_chain *gc_sym_list;
 610
 611   /* If a base output file is wanted, then this points to it */
 612   void *base_file;
 613
 614   /* The function to call when the executable or shared object is
 615      loaded.  */
 616   const char *init_function;
 617
 618   /* The function to call when the executable or shared object is
 619      unloaded.  */
 620   const char *fini_function;
 621
 622   /* Number of relaxation passes.  Usually only one relaxation pass
 623      is needed.  But a backend can have as many relaxation passes as
 624      necessary.  During bfd_relax_section call, it is set to the
 625      current pass, starting from 0.  */
 626   int relax_pass;
 627
 628   /* Number of relaxation trips.  This number is incremented every
 629      time the relaxation pass is restarted due to a previous
 630      relaxation returning true in *AGAIN.  */
 631   int relax_trip;
 632
 633   /* > 0 to treat protected data defined in the shared library as
 634      reference external.  0 to treat it as internal.  -1 to let
 635      backend to decide.  */
 636   int extern_protected_data;
 637
 638   /* 1 to make undefined weak symbols dynamic when building a dynamic
 639      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 640      the backend decide.  */
 641   int dynamic_undefined_weak;
 642
 643   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 644      should be generated/linked against.  Set to 1 if this feature
 645      is explicitly requested by the user, -1 if enabled by default.  */
 646   int pei386_auto_import;
 647
 648   /* Non-zero if runtime relocs for DATA items with non-zero addends
 649      in pei386 DLLs should be generated.  Set to 1 if this feature
 650      is explicitly requested by the user, -1 if enabled by default.  */
 651   int pei386_runtime_pseudo_reloc;
 652
 653   /* How many spare .dynamic DT_NULL entries should be added?  */
 654   unsigned int spare_dynamic_tags;
 655
 656   /* May be used to set DT_FLAGS for ELF. */
 657   bfd_vma flags;
 658
 659   /* May be used to set DT_FLAGS_1 for ELF. */
 660   bfd_vma flags_1;
 661
 662   /* May be used to set DT_GNU_FLAGS_1 for ELF. */
 663   bfd_vma gnu_flags_1;
 664
 665   /* May be used to set ELF visibility for __start_* / __stop_.  */
 666   unsigned int start_stop_visibility;
 667
 668   /* The maximum page size for ELF.  */
 669   bfd_vma maxpagesize;
 670
 671   /* The common page size for ELF.  */
 672   bfd_vma commonpagesize;
 673
 674   /* Start and end of RELRO region.  */
 675   bfd_vma relro_start, relro_end;
 676
 677   /* List of symbols should be dynamic.  */
 678   struct bfd_elf_dynamic_list *dynamic_list;
 679
 680   /* The version information.  */
 681   struct bfd_elf_version_tree *version_info;
 682 };
 683
 684 /* Some forward-definitions used by some callbacks.  */
 685
 686 struct elf_strtab_hash;
 687 struct elf_internal_sym;
 688
 689 /* This structures holds a set of callback functions.  These are called
 690    by the BFD linker routines.  */
 691
 692 struct bfd_link_callbacks
 693 {
 694   /* A function which is called when an object is added from an
 695      archive.  ABFD is the archive element being added.  NAME is the
 696      name of the symbol which caused the archive element to be pulled
 697      in.  This function may set *SUBSBFD to point to an alternative
 698      BFD from which symbols should in fact be added in place of the
 699      original BFD's symbols.  Returns TRUE if the object should be
 700      added, FALSE if it should be skipped.  */
 701   bfd_boolean (*add_archive_element)
 702     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 703   /* A function which is called when a symbol is found with multiple
 704      definitions.  H is the symbol which is defined multiple times.
 705      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 706      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 707   void (*multiple_definition)
 708     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 709      bfd *nbfd, asection *nsec, bfd_vma nval);
 710   /* A function which is called when a common symbol is defined
 711      multiple times.  H is the symbol appearing multiple times.
 712      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 713      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 714      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 715      is the size of the new symbol.  */
 716   void (*multiple_common)
 717     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 718      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 719   /* A function which is called to add a symbol to a set.  ENTRY is
 720      the link hash table entry for the set itself (e.g.,
 721      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 722      the set when generating a relocatable file, and is also used to
 723      get the size of the entry when generating an executable file.
 724      ABFD, SEC and VALUE identify the value to add to the set.  */
 725   void (*add_to_set)
 726     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 727      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 728   /* A function which is called when the name of a g++ constructor or
 729      destructor is found.  This is only called by some object file
 730      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 731      destructor.  This will use BFD_RELOC_CTOR when generating a
 732      relocatable file.  NAME is the name of the symbol found.  ABFD,
 733      SECTION and VALUE are the value of the symbol.  */
 734   void (*constructor)
 735     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 736      bfd *abfd, asection *sec, bfd_vma value);
 737   /* A function which is called to issue a linker warning.  For
 738      example, this is called when there is a reference to a warning
 739      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 740      of the symbol which triggered the warning; it may be NULL if
 741      there is none.  ABFD, SECTION and ADDRESS identify the location
 742      which trigerred the warning; either ABFD or SECTION or both may
 743      be NULL if the location is not known.  */
 744   void (*warning)
 745     (struct bfd_link_info *, const char *warning, const char *symbol,
 746      bfd *abfd, asection *section, bfd_vma address);
 747   /* A function which is called when a relocation is attempted against
 748      an undefined symbol.  NAME is the symbol which is undefined.
 749      ABFD, SECTION and ADDRESS identify the location from which the
 750      reference is made. IS_FATAL indicates whether an undefined symbol is
 751      a fatal error or not. In some cases SECTION may be NULL.  */
 752   void (*undefined_symbol)
 753     (struct bfd_link_info *, const char *name, bfd *abfd,
 754      asection *section, bfd_vma address, bfd_boolean is_fatal);
 755   /* A function which is called when a reloc overflow occurs. ENTRY is
 756      the link hash table entry for the symbol the reloc is against.
 757      NAME is the name of the local symbol or section the reloc is
 758      against, RELOC_NAME is the name of the relocation, and ADDEND is
 759      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 760      location at which the overflow occurs; if this is the result of a
 761      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 762      ABFD will be NULL.  */
 763   void (*reloc_overflow)
 764     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 765      const char *name, const char *reloc_name, bfd_vma addend,
 766      bfd *abfd, asection *section, bfd_vma address);
 767   /* A function which is called when a dangerous reloc is performed.
 768      MESSAGE is an appropriate message.
 769      ABFD, SECTION and ADDRESS identify the location at which the
 770      problem occurred; if this is the result of a
 771      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 772      ABFD will be NULL.  */
 773   void (*reloc_dangerous)
 774     (struct bfd_link_info *, const char *message,
 775      bfd *abfd, asection *section, bfd_vma address);
 776   /* A function which is called when a reloc is found to be attached
 777      to a symbol which is not being written out.  NAME is the name of
 778      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 779      the reloc; if this is the result of a
 780      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 781      ABFD will be NULL.  */
 782   void (*unattached_reloc)
 783     (struct bfd_link_info *, const char *name,
 784      bfd *abfd, asection *section, bfd_vma address);
 785   /* A function which is called when a symbol in notice_hash is
 786      defined or referenced.  H is the symbol, INH the indirect symbol
 787      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 788      the symbol.  If SECTION is bfd_und_section, this is a reference.
 789      FLAGS are the symbol BSF_* flags.  */
 790   bfd_boolean (*notice)
 791     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 792      struct bfd_link_hash_entry *inh,
 793      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 794   /* Error or warning link info message.  */
 795   void (*einfo)
 796     (const char *fmt, ...);
 797   /* General link info message.  */
 798   void (*info)
 799     (const char *fmt, ...);
 800   /* Message to be printed in linker map file.  */
 801   void (*minfo)
 802     (const char *fmt, ...);
 803   /* This callback provides a chance for users of the BFD library to
 804      override its decision about whether to place two adjacent sections
 805      into the same segment.  */
 806   bfd_boolean (*override_segment_assignment)
 807     (struct bfd_link_info *, bfd * abfd,
 808      asection * current_section, asection * previous_section,
 809      bfd_boolean new_segment);
 810   /* This callback provides a chance for callers of the BFD to examine the
 811      ELF (dynamic) string table once it is complete.  */
 812   void (*examine_strtab)
 813     (struct elf_strtab_hash *symstrtab);
 814   /* This callback is called just before a symbol is swapped out, so that the
 815      CTF machinery can look up symbols during construction.  The name is
 816      already an external strtab offset at this point.  */
 817   void (*ctf_new_symbol)
 818     (int symidx, struct elf_internal_sym *sym);
 819   /* Likewise, for dynamic symbols.  */
 820   void (*ctf_new_dynsym)
 821     (int symidx, struct elf_internal_sym *sym);
 822   /* This callback should emit the CTF section into a non-loadable section in
 823      the output BFD named .ctf or a name beginning with ".ctf.".  */
 824   void (*emit_ctf)
 825     (void);
 826 };
 827 \f
 828 /* The linker builds link_order structures which tell the code how to
 829    include input data in the output file.  */
 830
 831 /* These are the types of link_order structures.  */
 832
 833 enum bfd_link_order_type
 834 {
 835   bfd_undefined_link_order,     /* Undefined.  */
 836   bfd_indirect_link_order,      /* Built from a section.  */
 837   bfd_data_link_order,          /* Set to explicit data.  */
 838   bfd_section_reloc_link_order, /* Relocate against a section.  */
 839   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 840 };
 841
 842 /* This is the link_order structure itself.  These form a chain
 843    attached to the output section whose contents they are describing.  */
 844
 845 struct bfd_link_order
 846 {
 847   /* Next link_order in chain.  */
 848   struct bfd_link_order *next;
 849   /* Type of link_order.  */
 850   enum bfd_link_order_type type;
 851   /* Offset within output section in bytes.  */
 852   bfd_vma offset;
 853   /* Size within output section in octets.  */
 854   bfd_size_type size;
 855   /* Type specific information.  */
 856   union
 857     {
 858       struct
 859         {
 860           /* Section to include.  If this is used, then
 861              section->output_section must be the section the
 862              link_order is attached to, section->output_offset must
 863              equal the link_order offset field, and section->size
 864              must equal the link_order size field.  Maybe these
 865              restrictions should be relaxed someday.  */
 866           asection *section;
 867         } indirect;
 868       struct
 869         {
 870           /* Size of contents, or zero when contents should be filled by
 871              the architecture-dependent fill function.
 872              A non-zero value allows filling of the output section
 873              with an arbitrary repeated pattern.  */
 874           unsigned int size;
 875           /* Data to put into file.  */
 876           bfd_byte *contents;
 877         } data;
 878       struct
 879         {
 880           /* Description of reloc to generate.  Used for
 881              bfd_section_reloc_link_order and
 882              bfd_symbol_reloc_link_order.  */
 883           struct bfd_link_order_reloc *p;
 884         } reloc;
 885     } u;
 886 };
 887
 888 /* A linker order of type bfd_section_reloc_link_order or
 889    bfd_symbol_reloc_link_order means to create a reloc against a
 890    section or symbol, respectively.  This is used to implement -Ur to
 891    generate relocs for the constructor tables.  The
 892    bfd_link_order_reloc structure describes the reloc that BFD should
 893    create.  It is similar to a arelent, but I didn't use arelent
 894    because the linker does not know anything about most symbols, and
 895    any asymbol structure it creates will be partially meaningless.
 896    This information could logically be in the bfd_link_order struct,
 897    but I didn't want to waste the space since these types of relocs
 898    are relatively rare.  */
 899
 900 struct bfd_link_order_reloc
 901 {
 902   /* Reloc type.  */
 903   bfd_reloc_code_real_type reloc;
 904
 905   union
 906     {
 907       /* For type bfd_section_reloc_link_order, this is the section
 908          the reloc should be against.  This must be a section in the
 909          output BFD, not any of the input BFDs.  */
 910       asection *section;
 911       /* For type bfd_symbol_reloc_link_order, this is the name of the
 912          symbol the reloc should be against.  */
 913       const char *name;
 914     } u;
 915
 916   /* Addend to use.  The object file should contain zero.  The BFD
 917      backend is responsible for filling in the contents of the object
 918      file correctly.  For some object file formats (e.g., COFF) the
 919      addend must be stored into in the object file, and for some
 920      (e.g., SPARC a.out) it is kept in the reloc.  */
 921   bfd_vma addend;
 922 };
 923
 924 /* Allocate a new link_order for a section.  */
 925 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 926
 927 struct bfd_section_already_linked;
 928
 929 extern bfd_boolean bfd_section_already_linked_table_init (void);
 930 extern void bfd_section_already_linked_table_free (void);
 931 extern bfd_boolean _bfd_handle_already_linked
 932   (struct bfd_section *, struct bfd_section_already_linked *,
 933    struct bfd_link_info *);
 934
 935 extern struct bfd_section *_bfd_nearby_section
 936   (bfd *, struct bfd_section *, bfd_vma);
 937
 938 extern void _bfd_fix_excluded_sec_syms
 939   (bfd *, struct bfd_link_info *);
 940
 941 /* These structures are used to describe version information for the
 942    ELF linker.  These structures could be manipulated entirely inside
 943    BFD, but it would be a pain.  Instead, the regular linker sets up
 944    these structures, and then passes them into BFD.  */
 945
 946 /* Glob pattern for a version.  */
 947
 948 struct bfd_elf_version_expr
 949 {
 950   /* Next glob pattern for this version.  */
 951   struct bfd_elf_version_expr *next;
 952   /* Glob pattern.  */
 953   const char *pattern;
 954   /* Set if pattern is not a glob.  */
 955   unsigned int literal : 1;
 956   /* Defined by ".symver".  */
 957   unsigned int symver : 1;
 958   /* Defined by version script.  */
 959   unsigned int script : 1;
 960   /* Pattern type.  */
 961 #define BFD_ELF_VERSION_C_TYPE          1
 962 #define BFD_ELF_VERSION_CXX_TYPE        2
 963 #define BFD_ELF_VERSION_JAVA_TYPE       4
 964   unsigned int mask : 3;
 965 };
 966
 967 struct bfd_elf_version_expr_head
 968 {
 969   /* List of all patterns, both wildcards and non-wildcards.  */
 970   struct bfd_elf_version_expr *list;
 971   /* Hash table for non-wildcards.  */
 972   void *htab;
 973   /* Remaining patterns.  */
 974   struct bfd_elf_version_expr *remaining;
 975   /* What kind of pattern types are present in list (bitmask).  */
 976   unsigned int mask;
 977 };
 978
 979 /* Version dependencies.  */
 980
 981 struct bfd_elf_version_deps
 982 {
 983   /* Next dependency for this version.  */
 984   struct bfd_elf_version_deps *next;
 985   /* The version which this version depends upon.  */
 986   struct bfd_elf_version_tree *version_needed;
 987 };
 988
 989 /* A node in the version tree.  */
 990
 991 struct bfd_elf_version_tree
 992 {
 993   /* Next version.  */
 994   struct bfd_elf_version_tree *next;
 995   /* Name of this version.  */
 996   const char *name;
 997   /* Version number.  */
 998   unsigned int vernum;
 999   /* Regular expressions for global symbols in this version.  */
1000   struct bfd_elf_version_expr_head globals;
1001   /* Regular expressions for local symbols in this version.  */
1002   struct bfd_elf_version_expr_head locals;
1003   /* List of versions which this version depends upon.  */
1004   struct bfd_elf_version_deps *deps;
1005   /* Index of the version name.  This is used within BFD.  */
1006   unsigned int name_indx;
1007   /* Whether this version tree was used.  This is used within BFD.  */
1008   int used;
1009   /* Matching hook.  */
1010   struct bfd_elf_version_expr *(*match)
1011     (struct bfd_elf_version_expr_head *head,
1012      struct bfd_elf_version_expr *prev, const char *sym);
1013 };
1014
1015 struct bfd_elf_dynamic_list
1016 {
1017   struct bfd_elf_version_expr_head head;
1018   struct bfd_elf_version_expr *(*match)
1019     (struct bfd_elf_version_expr_head *head,
1020      struct bfd_elf_version_expr *prev, const char *sym);
1021 };
1022
1023 #endif