include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2020 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 typedef enum {with_flags, without_flags} flag_type;
 277
 278 /* A section flag list.  */
 279 struct flag_info_list
 280 {
 281   flag_type with;
 282   const char *name;
 283   bfd_boolean valid;
 284   struct flag_info_list *next;
 285 };
 286
 287 /* Section flag info.  */
 288 struct flag_info
 289 {
 290   flagword only_with_flags;
 291   flagword not_with_flags;
 292   struct flag_info_list *flag_list;
 293   bfd_boolean flags_initialized;
 294 };
 295
 296 struct bfd_elf_dynamic_list;
 297 struct bfd_elf_version_tree;
 298
 299 /* Types of output.  */
 300
 301 enum output_type
 302 {
 303   type_pde,
 304   type_pie,
 305   type_relocatable,
 306   type_dll,
 307 };
 308
 309 #define bfd_link_pde(info)         ((info)->type == type_pde)
 310 #define bfd_link_dll(info)         ((info)->type == type_dll)
 311 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 312 #define bfd_link_pie(info)         ((info)->type == type_pie)
 313 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 314 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 315
 316 /* This structure holds all the information needed to communicate
 317    between BFD and the linker when doing a link.  */
 318
 319 struct bfd_link_info
 320 {
 321   /* Output type.  */
 322   ENUM_BITFIELD (output_type) type : 2;
 323
 324   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 325   unsigned int symbolic: 1;
 326
 327   /* TRUE if executable should not contain copy relocs.
 328      Setting this true may result in a non-sharable text segment.  */
 329   unsigned int nocopyreloc: 1;
 330
 331   /* TRUE if BFD should export all symbols in the dynamic symbol table
 332      of an executable, rather than only those used.  */
 333   unsigned int export_dynamic: 1;
 334
 335   /* TRUE if a default symbol version should be created and used for
 336      exported symbols.  */
 337   unsigned int create_default_symver: 1;
 338
 339   /* TRUE if unreferenced sections should be removed.  */
 340   unsigned int gc_sections: 1;
 341
 342   /* TRUE if exported symbols should be kept during section gc.  */
 343   unsigned int gc_keep_exported: 1;
 344
 345   /* TRUE if every symbol should be reported back via the notice
 346      callback.  */
 347   unsigned int notice_all: 1;
 348
 349   /* TRUE if the LTO plugin is active.  */
 350   unsigned int lto_plugin_active: 1;
 351
 352   /* TRUE if global symbols in discarded sections should be stripped.  */
 353   unsigned int strip_discarded: 1;
 354
 355   /* TRUE if all data symbols should be dynamic.  */
 356   unsigned int dynamic_data: 1;
 357
 358   /* TRUE if section groups should be resolved.  */
 359   unsigned int resolve_section_groups: 1;
 360
 361   /* Set if output file is big-endian, or if that is unknown, from
 362      the command line or first input file endianness.  */
 363   unsigned int big_endian : 1;
 364
 365   /* Which symbols to strip.  */
 366   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 367
 368   /* Which local symbols to discard.  */
 369   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 370
 371   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 372   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 373
 374   /* Criteria for skipping symbols when determining
 375      whether to include an object from an archive.  */
 376   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 377
 378   /* What to do with unresolved symbols in an object file.
 379      When producing executables the default is GENERATE_ERROR.
 380      When producing shared libraries the default is IGNORE.  The
 381      assumption with shared libraries is that the reference will be
 382      resolved at load/execution time.  */
 383   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 384
 385   /* What to do with unresolved symbols in a shared library.
 386      The same defaults apply.  */
 387   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 388
 389   /* TRUE if unresolved symbols are to be warned, rather than errored.  */
 390   unsigned int warn_unresolved_syms: 1;
 391
 392   /* TRUE if shared objects should be linked directly, not shared.  */
 393   unsigned int static_link: 1;
 394
 395   /* TRUE if symbols should be retained in memory, FALSE if they
 396      should be freed and reread.  */
 397   unsigned int keep_memory: 1;
 398
 399   /* TRUE if BFD should generate relocation information in the final
 400      executable.  */
 401   unsigned int emitrelocations: 1;
 402
 403   /* TRUE if PT_GNU_RELRO segment should be created.  */
 404   unsigned int relro: 1;
 405
 406   /* TRUE if separate code segment should be created.  */
 407   unsigned int separate_code: 1;
 408
 409   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 410      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 411   unsigned int eh_frame_hdr_type: 2;
 412
 413   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 414   unsigned int warn_shared_textrel: 1;
 415
 416   /* TRUE if we should error when adding a DT_TEXTREL.  */
 417   unsigned int error_textrel: 1;
 418
 419   /* TRUE if .hash section should be created.  */
 420   unsigned int emit_hash: 1;
 421
 422   /* TRUE if .gnu.hash section should be created.  */
 423   unsigned int emit_gnu_hash: 1;
 424
 425   /* If TRUE reduce memory overheads, at the expense of speed. This will
 426      cause map file generation to use an O(N^2) algorithm and disable
 427      caching ELF symbol buffer.  */
 428   unsigned int reduce_memory_overheads: 1;
 429
 430   /* TRUE if the output file should be in a traditional format.  This
 431      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 432      on the output file, but may be checked when reading the input
 433      files.  */
 434   unsigned int traditional_format: 1;
 435
 436   /* TRUE if non-PLT relocs should be merged into one reloc section
 437      and sorted so that relocs against the same symbol come together.  */
 438   unsigned int combreloc: 1;
 439
 440   /* TRUE if a default symbol version should be created and used for
 441      imported symbols.  */
 442   unsigned int default_imported_symver: 1;
 443
 444   /* TRUE if the new ELF dynamic tags are enabled. */
 445   unsigned int new_dtags: 1;
 446
 447   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 448      linker created sections, TRUE if it should be omitted.  */
 449   unsigned int no_ld_generated_unwind_info: 1;
 450
 451   /* TRUE if BFD should generate a "task linked" object file,
 452      similar to relocatable but also with globals converted to
 453      statics.  */
 454   unsigned int task_link: 1;
 455
 456   /* TRUE if ok to have multiple definition.  */
 457   unsigned int allow_multiple_definition: 1;
 458
 459   /* TRUE if ok to have prohibit multiple definition of absolute symbols.  */
 460   unsigned int prohibit_multiple_definition_absolute: 1;
 461
 462   /* TRUE if ok to have version with no definition.  */
 463   unsigned int allow_undefined_version: 1;
 464
 465   /* TRUE if some symbols have to be dynamic, controlled by
 466      --dynamic-list command line options.  */
 467   unsigned int dynamic: 1;
 468
 469   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 470      flags.  */
 471   unsigned int execstack: 1;
 472
 473   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 474      flags.  */
 475   unsigned int noexecstack: 1;
 476
 477   /* TRUE if we want to produced optimized output files.  This might
 478      need much more time and therefore must be explicitly selected.  */
 479   unsigned int optimize: 1;
 480
 481   /* TRUE if user should be informed of removed unreferenced sections.  */
 482   unsigned int print_gc_sections: 1;
 483
 484   /* TRUE if we should warn alternate ELF machine code.  */
 485   unsigned int warn_alternate_em: 1;
 486
 487   /* TRUE if the linker script contained an explicit PHDRS command.  */
 488   unsigned int user_phdrs: 1;
 489
 490   /* TRUE if program headers ought to be loaded.  */
 491   unsigned int load_phdrs: 1;
 492
 493   /* TRUE if we should check relocations after all input files have
 494      been opened.  */
 495   unsigned int check_relocs_after_open_input: 1;
 496
 497   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 498   unsigned int nointerp: 1;
 499
 500   /* TRUE if common symbols should be treated as undefined.  */
 501   unsigned int inhibit_common_definition : 1;
 502
 503   /* TRUE if "-Map map" is passed to linker.  */
 504   unsigned int has_map_file : 1;
 505
 506   /* TRUE if "--enable-non-contiguous-regions" is passed to the
 507      linker.  */
 508   unsigned int non_contiguous_regions : 1;
 509
 510   /* TRUE if "--enable-non-contiguous-regions-warnings" is passed to
 511      the linker.  */
 512   unsigned int non_contiguous_regions_warnings : 1;
 513
 514   /* Char that may appear as the first char of a symbol, but should be
 515      skipped (like symbol_leading_char) when looking up symbols in
 516      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 517   char wrap_char;
 518
 519   /* Separator between archive and filename in linker script filespecs.  */
 520   char path_separator;
 521
 522   /* Compress DWARF debug sections.  */
 523   enum compressed_debug_section_type compress_debug;
 524
 525   /* Default stack size.  Zero means default (often zero itself), -1
 526      means explicitly zero-sized.  */
 527   bfd_signed_vma stacksize;
 528
 529   /* Enable or disable target specific optimizations.
 530
 531      Not all targets have optimizations to enable.
 532
 533      Normally these optimizations are disabled by default but some targets
 534      prefer to enable them by default.  So this field is a tri-state variable.
 535      The values are:
 536
 537      zero: Enable the optimizations (either from --relax being specified on
 538        the command line or the backend's before_allocation emulation function.
 539
 540      positive: The user has requested that these optimizations be disabled.
 541        (Via the --no-relax command line option).
 542
 543      negative: The optimizations are disabled.  (Set when initializing the
 544        args_type structure in ldmain.c:main.  */
 545   signed int disable_target_specific_optimizations;
 546
 547   /* Function callbacks.  */
 548   const struct bfd_link_callbacks *callbacks;
 549
 550   /* Hash table handled by BFD.  */
 551   struct bfd_link_hash_table *hash;
 552
 553   /* Hash table of symbols to keep.  This is NULL unless strip is
 554      strip_some.  */
 555   struct bfd_hash_table *keep_hash;
 556
 557   /* Hash table of symbols to report back via the notice callback.  If
 558      this is NULL, and notice_all is FALSE, then no symbols are
 559      reported back.  */
 560   struct bfd_hash_table *notice_hash;
 561
 562   /* Hash table of symbols which are being wrapped (the --wrap linker
 563      option).  If this is NULL, no symbols are being wrapped.  */
 564   struct bfd_hash_table *wrap_hash;
 565
 566   /* Hash table of symbols which may be left unresolved during
 567      a link.  If this is NULL, no symbols can be left unresolved.  */
 568   struct bfd_hash_table *ignore_hash;
 569
 570   /* The output BFD.  */
 571   bfd *output_bfd;
 572
 573   /* The import library generated.  */
 574   bfd *out_implib_bfd;
 575
 576   /* The list of input BFD's involved in the link.  These are chained
 577      together via the link.next field.  */
 578   bfd *input_bfds;
 579   bfd **input_bfds_tail;
 580
 581   /* If a symbol should be created for each input BFD, this is section
 582      where those symbols should be placed.  It must be a section in
 583      the output BFD.  It may be NULL, in which case no such symbols
 584      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 585      linker command language.  */
 586   asection *create_object_symbols_section;
 587
 588   /* List of global symbol names that are starting points for marking
 589      sections against garbage collection.  */
 590   struct bfd_sym_chain *gc_sym_list;
 591
 592   /* If a base output file is wanted, then this points to it */
 593   void *base_file;
 594
 595   /* The function to call when the executable or shared object is
 596      loaded.  */
 597   const char *init_function;
 598
 599   /* The function to call when the executable or shared object is
 600      unloaded.  */
 601   const char *fini_function;
 602
 603   /* Number of relaxation passes.  Usually only one relaxation pass
 604      is needed.  But a backend can have as many relaxation passes as
 605      necessary.  During bfd_relax_section call, it is set to the
 606      current pass, starting from 0.  */
 607   int relax_pass;
 608
 609   /* Number of relaxation trips.  This number is incremented every
 610      time the relaxation pass is restarted due to a previous
 611      relaxation returning true in *AGAIN.  */
 612   int relax_trip;
 613
 614   /* > 0 to treat protected data defined in the shared library as
 615      reference external.  0 to treat it as internal.  -1 to let
 616      backend to decide.  */
 617   int extern_protected_data;
 618
 619   /* 1 to make undefined weak symbols dynamic when building a dynamic
 620      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 621      the backend decide.  */
 622   int dynamic_undefined_weak;
 623
 624   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 625      should be generated/linked against.  Set to 1 if this feature
 626      is explicitly requested by the user, -1 if enabled by default.  */
 627   int pei386_auto_import;
 628
 629   /* Non-zero if runtime relocs for DATA items with non-zero addends
 630      in pei386 DLLs should be generated.  Set to 1 if this feature
 631      is explicitly requested by the user, -1 if enabled by default.  */
 632   int pei386_runtime_pseudo_reloc;
 633
 634   /* How many spare .dynamic DT_NULL entries should be added?  */
 635   unsigned int spare_dynamic_tags;
 636
 637   /* May be used to set DT_FLAGS for ELF. */
 638   bfd_vma flags;
 639
 640   /* May be used to set DT_FLAGS_1 for ELF. */
 641   bfd_vma flags_1;
 642
 643   /* Start and end of RELRO region.  */
 644   bfd_vma relro_start, relro_end;
 645
 646   /* List of symbols should be dynamic.  */
 647   struct bfd_elf_dynamic_list *dynamic_list;
 648
 649   /* The version information.  */
 650   struct bfd_elf_version_tree *version_info;
 651 };
 652
 653 /* Some forward-definitions used by some callbacks.  */
 654
 655 struct elf_strtab_hash;
 656 struct elf_sym_strtab;
 657
 658 /* This structures holds a set of callback functions.  These are called
 659    by the BFD linker routines.  */
 660
 661 struct bfd_link_callbacks
 662 {
 663   /* A function which is called when an object is added from an
 664      archive.  ABFD is the archive element being added.  NAME is the
 665      name of the symbol which caused the archive element to be pulled
 666      in.  This function may set *SUBSBFD to point to an alternative
 667      BFD from which symbols should in fact be added in place of the
 668      original BFD's symbols.  Returns TRUE if the object should be
 669      added, FALSE if it should be skipped.  */
 670   bfd_boolean (*add_archive_element)
 671     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 672   /* A function which is called when a symbol is found with multiple
 673      definitions.  H is the symbol which is defined multiple times.
 674      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 675      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 676   void (*multiple_definition)
 677     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 678      bfd *nbfd, asection *nsec, bfd_vma nval);
 679   /* A function which is called when a common symbol is defined
 680      multiple times.  H is the symbol appearing multiple times.
 681      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 682      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 683      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 684      is the size of the new symbol.  */
 685   void (*multiple_common)
 686     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 687      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 688   /* A function which is called to add a symbol to a set.  ENTRY is
 689      the link hash table entry for the set itself (e.g.,
 690      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 691      the set when generating a relocatable file, and is also used to
 692      get the size of the entry when generating an executable file.
 693      ABFD, SEC and VALUE identify the value to add to the set.  */
 694   void (*add_to_set)
 695     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 696      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 697   /* A function which is called when the name of a g++ constructor or
 698      destructor is found.  This is only called by some object file
 699      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 700      destructor.  This will use BFD_RELOC_CTOR when generating a
 701      relocatable file.  NAME is the name of the symbol found.  ABFD,
 702      SECTION and VALUE are the value of the symbol.  */
 703   void (*constructor)
 704     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 705      bfd *abfd, asection *sec, bfd_vma value);
 706   /* A function which is called to issue a linker warning.  For
 707      example, this is called when there is a reference to a warning
 708      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 709      of the symbol which triggered the warning; it may be NULL if
 710      there is none.  ABFD, SECTION and ADDRESS identify the location
 711      which trigerred the warning; either ABFD or SECTION or both may
 712      be NULL if the location is not known.  */
 713   void (*warning)
 714     (struct bfd_link_info *, const char *warning, const char *symbol,
 715      bfd *abfd, asection *section, bfd_vma address);
 716   /* A function which is called when a relocation is attempted against
 717      an undefined symbol.  NAME is the symbol which is undefined.
 718      ABFD, SECTION and ADDRESS identify the location from which the
 719      reference is made. IS_FATAL indicates whether an undefined symbol is
 720      a fatal error or not. In some cases SECTION may be NULL.  */
 721   void (*undefined_symbol)
 722     (struct bfd_link_info *, const char *name, bfd *abfd,
 723      asection *section, bfd_vma address, bfd_boolean is_fatal);
 724   /* A function which is called when a reloc overflow occurs. ENTRY is
 725      the link hash table entry for the symbol the reloc is against.
 726      NAME is the name of the local symbol or section the reloc is
 727      against, RELOC_NAME is the name of the relocation, and ADDEND is
 728      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 729      location at which the overflow occurs; if this is the result of a
 730      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 731      ABFD will be NULL.  */
 732   void (*reloc_overflow)
 733     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 734      const char *name, const char *reloc_name, bfd_vma addend,
 735      bfd *abfd, asection *section, bfd_vma address);
 736   /* A function which is called when a dangerous reloc is performed.
 737      MESSAGE is an appropriate message.
 738      ABFD, SECTION and ADDRESS identify the location at which the
 739      problem occurred; if this is the result of a
 740      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 741      ABFD will be NULL.  */
 742   void (*reloc_dangerous)
 743     (struct bfd_link_info *, const char *message,
 744      bfd *abfd, asection *section, bfd_vma address);
 745   /* A function which is called when a reloc is found to be attached
 746      to a symbol which is not being written out.  NAME is the name of
 747      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 748      the reloc; if this is the result of a
 749      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 750      ABFD will be NULL.  */
 751   void (*unattached_reloc)
 752     (struct bfd_link_info *, const char *name,
 753      bfd *abfd, asection *section, bfd_vma address);
 754   /* A function which is called when a symbol in notice_hash is
 755      defined or referenced.  H is the symbol, INH the indirect symbol
 756      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 757      the symbol.  If SECTION is bfd_und_section, this is a reference.
 758      FLAGS are the symbol BSF_* flags.  */
 759   bfd_boolean (*notice)
 760     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 761      struct bfd_link_hash_entry *inh,
 762      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 763   /* Error or warning link info message.  */
 764   void (*einfo)
 765     (const char *fmt, ...);
 766   /* General link info message.  */
 767   void (*info)
 768     (const char *fmt, ...);
 769   /* Message to be printed in linker map file.  */
 770   void (*minfo)
 771     (const char *fmt, ...);
 772   /* This callback provides a chance for users of the BFD library to
 773      override its decision about whether to place two adjacent sections
 774      into the same segment.  */
 775   bfd_boolean (*override_segment_assignment)
 776     (struct bfd_link_info *, bfd * abfd,
 777      asection * current_section, asection * previous_section,
 778      bfd_boolean new_segment);
 779   /* This callback provides a chance for callers of the BFD to examine the
 780      ELF string table and symbol table once they are complete and indexes and
 781      offsets assigned.  */
 782   void (*examine_strtab)
 783     (struct elf_sym_strtab *syms, bfd_size_type symcount,
 784      struct elf_strtab_hash *symstrtab);
 785   /* This callback should emit the CTF section into a non-loadable section in
 786      the output BFD named .ctf or a name beginning with ".ctf.".  */
 787   void (*emit_ctf)
 788     (void);
 789 };
 790 \f
 791 /* The linker builds link_order structures which tell the code how to
 792    include input data in the output file.  */
 793
 794 /* These are the types of link_order structures.  */
 795
 796 enum bfd_link_order_type
 797 {
 798   bfd_undefined_link_order,     /* Undefined.  */
 799   bfd_indirect_link_order,      /* Built from a section.  */
 800   bfd_data_link_order,          /* Set to explicit data.  */
 801   bfd_section_reloc_link_order, /* Relocate against a section.  */
 802   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 803 };
 804
 805 /* This is the link_order structure itself.  These form a chain
 806    attached to the output section whose contents they are describing.  */
 807
 808 struct bfd_link_order
 809 {
 810   /* Next link_order in chain.  */
 811   struct bfd_link_order *next;
 812   /* Type of link_order.  */
 813   enum bfd_link_order_type type;
 814   /* Offset within output section in bytes.  */
 815   bfd_vma offset;
 816   /* Size within output section in octets.  */
 817   bfd_size_type size;
 818   /* Type specific information.  */
 819   union
 820     {
 821       struct
 822         {
 823           /* Section to include.  If this is used, then
 824              section->output_section must be the section the
 825              link_order is attached to, section->output_offset must
 826              equal the link_order offset field, and section->size
 827              must equal the link_order size field.  Maybe these
 828              restrictions should be relaxed someday.  */
 829           asection *section;
 830         } indirect;
 831       struct
 832         {
 833           /* Size of contents, or zero when contents should be filled by
 834              the architecture-dependent fill function.
 835              A non-zero value allows filling of the output section
 836              with an arbitrary repeated pattern.  */
 837           unsigned int size;
 838           /* Data to put into file.  */
 839           bfd_byte *contents;
 840         } data;
 841       struct
 842         {
 843           /* Description of reloc to generate.  Used for
 844              bfd_section_reloc_link_order and
 845              bfd_symbol_reloc_link_order.  */
 846           struct bfd_link_order_reloc *p;
 847         } reloc;
 848     } u;
 849 };
 850
 851 /* A linker order of type bfd_section_reloc_link_order or
 852    bfd_symbol_reloc_link_order means to create a reloc against a
 853    section or symbol, respectively.  This is used to implement -Ur to
 854    generate relocs for the constructor tables.  The
 855    bfd_link_order_reloc structure describes the reloc that BFD should
 856    create.  It is similar to a arelent, but I didn't use arelent
 857    because the linker does not know anything about most symbols, and
 858    any asymbol structure it creates will be partially meaningless.
 859    This information could logically be in the bfd_link_order struct,
 860    but I didn't want to waste the space since these types of relocs
 861    are relatively rare.  */
 862
 863 struct bfd_link_order_reloc
 864 {
 865   /* Reloc type.  */
 866   bfd_reloc_code_real_type reloc;
 867
 868   union
 869     {
 870       /* For type bfd_section_reloc_link_order, this is the section
 871          the reloc should be against.  This must be a section in the
 872          output BFD, not any of the input BFDs.  */
 873       asection *section;
 874       /* For type bfd_symbol_reloc_link_order, this is the name of the
 875          symbol the reloc should be against.  */
 876       const char *name;
 877     } u;
 878
 879   /* Addend to use.  The object file should contain zero.  The BFD
 880      backend is responsible for filling in the contents of the object
 881      file correctly.  For some object file formats (e.g., COFF) the
 882      addend must be stored into in the object file, and for some
 883      (e.g., SPARC a.out) it is kept in the reloc.  */
 884   bfd_vma addend;
 885 };
 886
 887 /* Allocate a new link_order for a section.  */
 888 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 889
 890 struct bfd_section_already_linked;
 891
 892 extern bfd_boolean bfd_section_already_linked_table_init (void);
 893 extern void bfd_section_already_linked_table_free (void);
 894 extern bfd_boolean _bfd_handle_already_linked
 895   (struct bfd_section *, struct bfd_section_already_linked *,
 896    struct bfd_link_info *);
 897
 898 extern struct bfd_section *_bfd_nearby_section
 899   (bfd *, struct bfd_section *, bfd_vma);
 900
 901 extern void _bfd_fix_excluded_sec_syms
 902   (bfd *, struct bfd_link_info *);
 903
 904 /* These structures are used to describe version information for the
 905    ELF linker.  These structures could be manipulated entirely inside
 906    BFD, but it would be a pain.  Instead, the regular linker sets up
 907    these structures, and then passes them into BFD.  */
 908
 909 /* Glob pattern for a version.  */
 910
 911 struct bfd_elf_version_expr
 912 {
 913   /* Next glob pattern for this version.  */
 914   struct bfd_elf_version_expr *next;
 915   /* Glob pattern.  */
 916   const char *pattern;
 917   /* Set if pattern is not a glob.  */
 918   unsigned int literal : 1;
 919   /* Defined by ".symver".  */
 920   unsigned int symver : 1;
 921   /* Defined by version script.  */
 922   unsigned int script : 1;
 923   /* Pattern type.  */
 924 #define BFD_ELF_VERSION_C_TYPE          1
 925 #define BFD_ELF_VERSION_CXX_TYPE        2
 926 #define BFD_ELF_VERSION_JAVA_TYPE       4
 927   unsigned int mask : 3;
 928 };
 929
 930 struct bfd_elf_version_expr_head
 931 {
 932   /* List of all patterns, both wildcards and non-wildcards.  */
 933   struct bfd_elf_version_expr *list;
 934   /* Hash table for non-wildcards.  */
 935   void *htab;
 936   /* Remaining patterns.  */
 937   struct bfd_elf_version_expr *remaining;
 938   /* What kind of pattern types are present in list (bitmask).  */
 939   unsigned int mask;
 940 };
 941
 942 /* Version dependencies.  */
 943
 944 struct bfd_elf_version_deps
 945 {
 946   /* Next dependency for this version.  */
 947   struct bfd_elf_version_deps *next;
 948   /* The version which this version depends upon.  */
 949   struct bfd_elf_version_tree *version_needed;
 950 };
 951
 952 /* A node in the version tree.  */
 953
 954 struct bfd_elf_version_tree
 955 {
 956   /* Next version.  */
 957   struct bfd_elf_version_tree *next;
 958   /* Name of this version.  */
 959   const char *name;
 960   /* Version number.  */
 961   unsigned int vernum;
 962   /* Regular expressions for global symbols in this version.  */
 963   struct bfd_elf_version_expr_head globals;
 964   /* Regular expressions for local symbols in this version.  */
 965   struct bfd_elf_version_expr_head locals;
 966   /* List of versions which this version depends upon.  */
 967   struct bfd_elf_version_deps *deps;
 968   /* Index of the version name.  This is used within BFD.  */
 969   unsigned int name_indx;
 970   /* Whether this version tree was used.  This is used within BFD.  */
 971   int used;
 972   /* Matching hook.  */
 973   struct bfd_elf_version_expr *(*match)
 974     (struct bfd_elf_version_expr_head *head,
 975      struct bfd_elf_version_expr *prev, const char *sym);
 976 };
 977
 978 struct bfd_elf_dynamic_list
 979 {
 980   struct bfd_elf_version_expr_head head;
 981   struct bfd_elf_version_expr *(*match)
 982     (struct bfd_elf_version_expr_head *head,
 983      struct bfd_elf_version_expr *prev, const char *sym);
 984 };
 985
 986 #endif