include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2018 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 regular object file,
 104      as distinct from a LTO IR object file.  */
 105   unsigned int non_ir_ref_regular : 1;
 106
 107   /* Symbol is referenced in a normal dynamic object file,
 108      as distinct from a LTO IR object file.  */
 109   unsigned int non_ir_ref_dynamic : 1;
 110
 111   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 112      in a linker script.  */
 113   unsigned int linker_def : 1;
 114
 115   /* Symbol defined in a linker script.  */
 116   unsigned int ldscript_def : 1;
 117
 118   /* A union of information depending upon the type.  */
 119   union
 120     {
 121       /* Nothing is kept for bfd_hash_new.  */
 122       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 123       struct
 124         {
 125           /* Undefined and common symbols are kept in a linked list through
 126              this field.  This field is present in all of the union element
 127              so that we don't need to remove entries from the list when we
 128              change their type.  Removing entries would either require the
 129              list to be doubly linked, which would waste more memory, or
 130              require a traversal.  When an undefined or common symbol is
 131              created, it should be added to this list, the head of which is in
 132              the link hash table itself.  As symbols are defined, they need
 133              not be removed from the list; anything which reads the list must
 134              doublecheck the symbol type.
 135
 136              Weak symbols are not kept on this list.
 137
 138              Defined and defweak symbols use this field as a reference marker.
 139              If the field is not NULL, or this structure is the tail of the
 140              undefined symbol list, the symbol has been referenced.  If the
 141              symbol is undefined and becomes defined, this field will
 142              automatically be non-NULL since the symbol will have been on the
 143              undefined symbol list.  */
 144           struct bfd_link_hash_entry *next;
 145           /* BFD symbol was found in.  */
 146           bfd *abfd;
 147         } undef;
 148       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 149       struct
 150         {
 151           struct bfd_link_hash_entry *next;
 152           /* Symbol section.  */
 153           asection *section;
 154           /* Symbol value.  */
 155           bfd_vma value;
 156         } def;
 157       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 158       struct
 159         {
 160           struct bfd_link_hash_entry *next;
 161           /* Real symbol.  */
 162           struct bfd_link_hash_entry *link;
 163           /* Warning message (bfd_link_hash_warning only).  */
 164           const char *warning;
 165         } i;
 166       /* bfd_link_hash_common.  */
 167       struct
 168         {
 169           struct bfd_link_hash_entry *next;
 170           /* The linker needs to know three things about common
 171              symbols: the size, the alignment, and the section in
 172              which the symbol should be placed.  We store the size
 173              here, and we allocate a small structure to hold the
 174              section and the alignment.  The alignment is stored as a
 175              power of two.  We don't store all the information
 176              directly because we don't want to increase the size of
 177              the union; this structure is a major space user in the
 178              linker.  */
 179           struct bfd_link_hash_common_entry *p;
 180           /* Common symbol size.  */
 181           bfd_size_type size;
 182         } c;
 183     } u;
 184 };
 185
 186 /* This is the link hash table.  It is a derived class of
 187    bfd_hash_table.  */
 188
 189 struct bfd_link_hash_table
 190 {
 191   /* The hash table itself.  */
 192   struct bfd_hash_table table;
 193   /* A linked list of undefined and common symbols, linked through the
 194      next field in the bfd_link_hash_entry structure.  */
 195   struct bfd_link_hash_entry *undefs;
 196   /* Entries are added to the tail of the undefs list.  */
 197   struct bfd_link_hash_entry *undefs_tail;
 198   /* Function to free the hash table on closing BFD.  */
 199   void (*hash_table_free) (bfd *);
 200   /* The type of the link hash table.  */
 201   enum bfd_link_hash_table_type type;
 202 };
 203
 204 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 205    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 206    the real symbol.  */
 207 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 208   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 209    bfd_boolean copy, bfd_boolean follow);
 210
 211 /* Look up an entry in the main linker hash table if the symbol might
 212    be wrapped.  This should only be used for references to an
 213    undefined symbol, not for definitions of a symbol.  */
 214
 215 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 216   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 217    bfd_boolean, bfd_boolean);
 218
 219 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 220    and the remainder is found in wrap_hash, return the real symbol.  */
 221
 222 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 223   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 224
 225 /* Traverse a link hash table.  */
 226 extern void bfd_link_hash_traverse
 227   (struct bfd_link_hash_table *,
 228     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 229     void *);
 230
 231 /* Add an entry to the undefs list.  */
 232 extern void bfd_link_add_undef
 233   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 234
 235 /* Remove symbols from the undefs list that don't belong there.  */
 236 extern void bfd_link_repair_undef_list
 237   (struct bfd_link_hash_table *table);
 238
 239 /* Read symbols and cache symbol pointer array in outsymbols.  */
 240 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 241
 242 /* Check the relocs in the BFD.  Called after all the input
 243    files have been loaded, and garbage collection has tagged
 244    any unneeded sections.  */
 245 extern bfd_boolean bfd_link_check_relocs (bfd *,struct bfd_link_info *);
 246
 247 struct bfd_sym_chain
 248 {
 249   struct bfd_sym_chain *next;
 250   const char *name;
 251 };
 252 \f
 253 /* How to handle unresolved symbols.
 254    There are four possibilities which are enumerated below:  */
 255 enum report_method
 256 {
 257   /* This is the initial value when then link_info structure is created.
 258      It allows the various stages of the linker to determine whether they
 259      allowed to set the value.  */
 260   RM_NOT_YET_SET = 0,
 261   RM_IGNORE,
 262   RM_GENERATE_WARNING,
 263   RM_GENERATE_ERROR
 264 };
 265
 266 typedef enum {with_flags, without_flags} flag_type;
 267
 268 /* A section flag list.  */
 269 struct flag_info_list
 270 {
 271   flag_type with;
 272   const char *name;
 273   bfd_boolean valid;
 274   struct flag_info_list *next;
 275 };
 276
 277 /* Section flag info.  */
 278 struct flag_info
 279 {
 280   flagword only_with_flags;
 281   flagword not_with_flags;
 282   struct flag_info_list *flag_list;
 283   bfd_boolean flags_initialized;
 284 };
 285
 286 struct bfd_elf_dynamic_list;
 287 struct bfd_elf_version_tree;
 288
 289 /* Types of output.  */
 290
 291 enum output_type
 292 {
 293   type_pde,
 294   type_pie,
 295   type_relocatable,
 296   type_dll,
 297 };
 298
 299 #define bfd_link_pde(info)         ((info)->type == type_pde)
 300 #define bfd_link_dll(info)         ((info)->type == type_dll)
 301 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 302 #define bfd_link_pie(info)         ((info)->type == type_pie)
 303 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 304 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 305
 306 /* This structure holds all the information needed to communicate
 307    between BFD and the linker when doing a link.  */
 308
 309 struct bfd_link_info
 310 {
 311   /* Output type.  */
 312   ENUM_BITFIELD (output_type) type : 2;
 313
 314   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 315   unsigned int symbolic: 1;
 316
 317   /* TRUE if executable should not contain copy relocs.
 318      Setting this true may result in a non-sharable text segment.  */
 319   unsigned int nocopyreloc: 1;
 320
 321   /* TRUE if BFD should export all symbols in the dynamic symbol table
 322      of an executable, rather than only those used.  */
 323   unsigned int export_dynamic: 1;
 324
 325   /* TRUE if a default symbol version should be created and used for
 326      exported symbols.  */
 327   unsigned int create_default_symver: 1;
 328
 329   /* TRUE if unreferenced sections should be removed.  */
 330   unsigned int gc_sections: 1;
 331
 332   /* TRUE if exported symbols should be kept during section gc.  */
 333   unsigned int gc_keep_exported: 1;
 334
 335   /* TRUE if every symbol should be reported back via the notice
 336      callback.  */
 337   unsigned int notice_all: 1;
 338
 339   /* TRUE if the LTO plugin is active.  */
 340   unsigned int lto_plugin_active: 1;
 341
 342   /* TRUE if global symbols in discarded sections should be stripped.  */
 343   unsigned int strip_discarded: 1;
 344
 345   /* TRUE if all data symbols should be dynamic.  */
 346   unsigned int dynamic_data: 1;
 347
 348   /* TRUE if section groups should be resolved.  */
 349   unsigned int resolve_section_groups: 1;
 350
 351   /* Which symbols to strip.  */
 352   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 353
 354   /* Which local symbols to discard.  */
 355   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 356
 357   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 358   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 359
 360   /* Criteria for skipping symbols when determining
 361      whether to include an object from an archive. */
 362   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 363
 364   /* What to do with unresolved symbols in an object file.
 365      When producing executables the default is GENERATE_ERROR.
 366      When producing shared libraries the default is IGNORE.  The
 367      assumption with shared libraries is that the reference will be
 368      resolved at load/execution time.  */
 369   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 370
 371   /* What to do with unresolved symbols in a shared library.
 372      The same defaults apply.  */
 373   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 374
 375   /* TRUE if shared objects should be linked directly, not shared.  */
 376   unsigned int static_link: 1;
 377
 378   /* TRUE if symbols should be retained in memory, FALSE if they
 379      should be freed and reread.  */
 380   unsigned int keep_memory: 1;
 381
 382   /* TRUE if BFD should generate relocation information in the final
 383      executable.  */
 384   unsigned int emitrelocations: 1;
 385
 386   /* TRUE if PT_GNU_RELRO segment should be created.  */
 387   unsigned int relro: 1;
 388
 389   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 390      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 391   unsigned int eh_frame_hdr_type: 2;
 392
 393   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 394   unsigned int warn_shared_textrel: 1;
 395
 396   /* TRUE if we should error when adding a DT_TEXTREL.  */
 397   unsigned int error_textrel: 1;
 398
 399   /* TRUE if .hash section should be created.  */
 400   unsigned int emit_hash: 1;
 401
 402   /* TRUE if .gnu.hash section should be created.  */
 403   unsigned int emit_gnu_hash: 1;
 404
 405   /* If TRUE reduce memory overheads, at the expense of speed. This will
 406      cause map file generation to use an O(N^2) algorithm and disable
 407      caching ELF symbol buffer.  */
 408   unsigned int reduce_memory_overheads: 1;
 409
 410   /* TRUE if the output file should be in a traditional format.  This
 411      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 412      on the output file, but may be checked when reading the input
 413      files.  */
 414   unsigned int traditional_format: 1;
 415
 416   /* TRUE if non-PLT relocs should be merged into one reloc section
 417      and sorted so that relocs against the same symbol come together.  */
 418   unsigned int combreloc: 1;
 419
 420   /* TRUE if a default symbol version should be created and used for
 421      imported symbols.  */
 422   unsigned int default_imported_symver: 1;
 423
 424   /* TRUE if the new ELF dynamic tags are enabled. */
 425   unsigned int new_dtags: 1;
 426
 427   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 428      linker created sections, TRUE if it should be omitted.  */
 429   unsigned int no_ld_generated_unwind_info: 1;
 430
 431   /* TRUE if BFD should generate a "task linked" object file,
 432      similar to relocatable but also with globals converted to
 433      statics.  */
 434   unsigned int task_link: 1;
 435
 436   /* TRUE if ok to have multiple definition.  */
 437   unsigned int allow_multiple_definition: 1;
 438
 439   /* TRUE if ok to have version with no definition.  */
 440   unsigned int allow_undefined_version: 1;
 441
 442   /* TRUE if some symbols have to be dynamic, controlled by
 443      --dynamic-list command line options.  */
 444   unsigned int dynamic: 1;
 445
 446   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 447      flags.  */
 448   unsigned int execstack: 1;
 449
 450   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 451      flags.  */
 452   unsigned int noexecstack: 1;
 453
 454   /* TRUE if we want to produced optimized output files.  This might
 455      need much more time and therefore must be explicitly selected.  */
 456   unsigned int optimize: 1;
 457
 458   /* TRUE if user should be informed of removed unreferenced sections.  */
 459   unsigned int print_gc_sections: 1;
 460
 461   /* TRUE if we should warn alternate ELF machine code.  */
 462   unsigned int warn_alternate_em: 1;
 463
 464   /* TRUE if the linker script contained an explicit PHDRS command.  */
 465   unsigned int user_phdrs: 1;
 466
 467   /* TRUE if we should check relocations after all input files have
 468      been opened.  */
 469   unsigned int check_relocs_after_open_input: 1;
 470
 471   /* TRUE if BND prefix in PLT entries is always generated.  */
 472   unsigned int bndplt: 1;
 473
 474   /* TRUE if IBT-enabled PLT entries should be generated.  */
 475   unsigned int ibtplt: 1;
 476
 477   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_IBT should be generated.  */
 478   unsigned int ibt: 1;
 479
 480   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_SHSTK should be generated.  */
 481   unsigned int shstk: 1;
 482
 483   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 484   unsigned int nointerp: 1;
 485
 486   /* TRUE if we shouldn't check relocation overflow.  */
 487   unsigned int no_reloc_overflow_check: 1;
 488
 489   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
 490   unsigned int call_nop_as_suffix : 1;
 491
 492   /* TRUE if common symbols should be treated as undefined.  */
 493   unsigned int inhibit_common_definition : 1;
 494
 495   /* The 1-byte NOP for x86 call instruction.  */
 496   char call_nop_byte;
 497
 498   /* Char that may appear as the first char of a symbol, but should be
 499      skipped (like symbol_leading_char) when looking up symbols in
 500      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 501   char wrap_char;
 502
 503   /* Separator between archive and filename in linker script filespecs.  */
 504   char path_separator;
 505
 506   /* Compress DWARF debug sections.  */
 507   enum compressed_debug_section_type compress_debug;
 508
 509   /* Default stack size.  Zero means default (often zero itself), -1
 510      means explicitly zero-sized.  */
 511   bfd_signed_vma stacksize;
 512
 513   /* Enable or disable target specific optimizations.
 514
 515      Not all targets have optimizations to enable.
 516
 517      Normally these optimizations are disabled by default but some targets
 518      prefer to enable them by default.  So this field is a tri-state variable.
 519      The values are:
 520
 521      zero: Enable the optimizations (either from --relax being specified on
 522        the command line or the backend's before_allocation emulation function.
 523
 524      positive: The user has requested that these optimizations be disabled.
 525        (Via the --no-relax command line option).
 526
 527      negative: The optimizations are disabled.  (Set when initializing the
 528        args_type structure in ldmain.c:main.  */
 529   signed int disable_target_specific_optimizations;
 530
 531   /* Function callbacks.  */
 532   const struct bfd_link_callbacks *callbacks;
 533
 534   /* Hash table handled by BFD.  */
 535   struct bfd_link_hash_table *hash;
 536
 537   /* Hash table of symbols to keep.  This is NULL unless strip is
 538      strip_some.  */
 539   struct bfd_hash_table *keep_hash;
 540
 541   /* Hash table of symbols to report back via the notice callback.  If
 542      this is NULL, and notice_all is FALSE, then no symbols are
 543      reported back.  */
 544   struct bfd_hash_table *notice_hash;
 545
 546   /* Hash table of symbols which are being wrapped (the --wrap linker
 547      option).  If this is NULL, no symbols are being wrapped.  */
 548   struct bfd_hash_table *wrap_hash;
 549
 550   /* Hash table of symbols which may be left unresolved during
 551      a link.  If this is NULL, no symbols can be left unresolved.  */
 552   struct bfd_hash_table *ignore_hash;
 553
 554   /* The output BFD.  */
 555   bfd *output_bfd;
 556
 557   /* The import library generated.  */
 558   bfd *out_implib_bfd;
 559
 560   /* The list of input BFD's involved in the link.  These are chained
 561      together via the link.next field.  */
 562   bfd *input_bfds;
 563   bfd **input_bfds_tail;
 564
 565   /* If a symbol should be created for each input BFD, this is section
 566      where those symbols should be placed.  It must be a section in
 567      the output BFD.  It may be NULL, in which case no such symbols
 568      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 569      linker command language.  */
 570   asection *create_object_symbols_section;
 571
 572   /* List of global symbol names that are starting points for marking
 573      sections against garbage collection.  */
 574   struct bfd_sym_chain *gc_sym_list;
 575
 576   /* If a base output file is wanted, then this points to it */
 577   void *base_file;
 578
 579   /* The function to call when the executable or shared object is
 580      loaded.  */
 581   const char *init_function;
 582
 583   /* The function to call when the executable or shared object is
 584      unloaded.  */
 585   const char *fini_function;
 586
 587   /* Number of relaxation passes.  Usually only one relaxation pass
 588      is needed.  But a backend can have as many relaxation passes as
 589      necessary.  During bfd_relax_section call, it is set to the
 590      current pass, starting from 0.  */
 591   int relax_pass;
 592
 593   /* Number of relaxation trips.  This number is incremented every
 594      time the relaxation pass is restarted due to a previous
 595      relaxation returning true in *AGAIN.  */
 596   int relax_trip;
 597
 598   /* > 0 to treat protected data defined in the shared library as
 599      reference external.  0 to treat it as internal.  -1 to let
 600      backend to decide.  */
 601   int extern_protected_data;
 602
 603   /* 1 to make undefined weak symbols dynamic when building a dynamic
 604      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 605      the backend decide.  */
 606   int dynamic_undefined_weak;
 607
 608   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 609      should be generated/linked against.  Set to 1 if this feature
 610      is explicitly requested by the user, -1 if enabled by default.  */
 611   int pei386_auto_import;
 612
 613   /* Non-zero if runtime relocs for DATA items with non-zero addends
 614      in pei386 DLLs should be generated.  Set to 1 if this feature
 615      is explicitly requested by the user, -1 if enabled by default.  */
 616   int pei386_runtime_pseudo_reloc;
 617
 618   /* How many spare .dynamic DT_NULL entries should be added?  */
 619   unsigned int spare_dynamic_tags;
 620
 621   /* May be used to set DT_FLAGS for ELF. */
 622   bfd_vma flags;
 623
 624   /* May be used to set DT_FLAGS_1 for ELF. */
 625   bfd_vma flags_1;
 626
 627   /* Start and end of RELRO region.  */
 628   bfd_vma relro_start, relro_end;
 629
 630   /* List of symbols should be dynamic.  */
 631   struct bfd_elf_dynamic_list *dynamic_list;
 632
 633   /* The version information.  */
 634   struct bfd_elf_version_tree *version_info;
 635 };
 636
 637 /* This structures holds a set of callback functions.  These are called
 638    by the BFD linker routines.  */
 639
 640 struct bfd_link_callbacks
 641 {
 642   /* A function which is called when an object is added from an
 643      archive.  ABFD is the archive element being added.  NAME is the
 644      name of the symbol which caused the archive element to be pulled
 645      in.  This function may set *SUBSBFD to point to an alternative
 646      BFD from which symbols should in fact be added in place of the
 647      original BFD's symbols.  Returns TRUE if the object should be
 648      added, FALSE if it should be skipped.  */
 649   bfd_boolean (*add_archive_element)
 650     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 651   /* A function which is called when a symbol is found with multiple
 652      definitions.  H is the symbol which is defined multiple times.
 653      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 654      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 655   void (*multiple_definition)
 656     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 657      bfd *nbfd, asection *nsec, bfd_vma nval);
 658   /* A function which is called when a common symbol is defined
 659      multiple times.  H is the symbol appearing multiple times.
 660      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 661      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 662      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 663      is the size of the new symbol.  */
 664   void (*multiple_common)
 665     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 666      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 667   /* A function which is called to add a symbol to a set.  ENTRY is
 668      the link hash table entry for the set itself (e.g.,
 669      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 670      the set when generating a relocatable file, and is also used to
 671      get the size of the entry when generating an executable file.
 672      ABFD, SEC and VALUE identify the value to add to the set.  */
 673   void (*add_to_set)
 674     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 675      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 676   /* A function which is called when the name of a g++ constructor or
 677      destructor is found.  This is only called by some object file
 678      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 679      destructor.  This will use BFD_RELOC_CTOR when generating a
 680      relocatable file.  NAME is the name of the symbol found.  ABFD,
 681      SECTION and VALUE are the value of the symbol.  */
 682   void (*constructor)
 683     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 684      bfd *abfd, asection *sec, bfd_vma value);
 685   /* A function which is called to issue a linker warning.  For
 686      example, this is called when there is a reference to a warning
 687      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 688      of the symbol which triggered the warning; it may be NULL if
 689      there is none.  ABFD, SECTION and ADDRESS identify the location
 690      which trigerred the warning; either ABFD or SECTION or both may
 691      be NULL if the location is not known.  */
 692   void (*warning)
 693     (struct bfd_link_info *, const char *warning, const char *symbol,
 694      bfd *abfd, asection *section, bfd_vma address);
 695   /* A function which is called when a relocation is attempted against
 696      an undefined symbol.  NAME is the symbol which is undefined.
 697      ABFD, SECTION and ADDRESS identify the location from which the
 698      reference is made. IS_FATAL indicates whether an undefined symbol is
 699      a fatal error or not. In some cases SECTION may be NULL.  */
 700   void (*undefined_symbol)
 701     (struct bfd_link_info *, const char *name, bfd *abfd,
 702      asection *section, bfd_vma address, bfd_boolean is_fatal);
 703   /* A function which is called when a reloc overflow occurs. ENTRY is
 704      the link hash table entry for the symbol the reloc is against.
 705      NAME is the name of the local symbol or section the reloc is
 706      against, RELOC_NAME is the name of the relocation, and ADDEND is
 707      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 708      location at which the overflow occurs; if this is the result of a
 709      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 710      ABFD will be NULL.  */
 711   void (*reloc_overflow)
 712     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 713      const char *name, const char *reloc_name, bfd_vma addend,
 714      bfd *abfd, asection *section, bfd_vma address);
 715   /* A function which is called when a dangerous reloc is performed.
 716      MESSAGE is an appropriate message.
 717      ABFD, SECTION and ADDRESS identify the location at which the
 718      problem occurred; if this is the result of a
 719      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 720      ABFD will be NULL.  */
 721   void (*reloc_dangerous)
 722     (struct bfd_link_info *, const char *message,
 723      bfd *abfd, asection *section, bfd_vma address);
 724   /* A function which is called when a reloc is found to be attached
 725      to a symbol which is not being written out.  NAME is the name of
 726      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 727      the reloc; if this is the result of a
 728      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 729      ABFD will be NULL.  */
 730   void (*unattached_reloc)
 731     (struct bfd_link_info *, const char *name,
 732      bfd *abfd, asection *section, bfd_vma address);
 733   /* A function which is called when a symbol in notice_hash is
 734      defined or referenced.  H is the symbol, INH the indirect symbol
 735      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 736      the symbol.  If SECTION is bfd_und_section, this is a reference.
 737      FLAGS are the symbol BSF_* flags.  */
 738   bfd_boolean (*notice)
 739     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 740      struct bfd_link_hash_entry *inh,
 741      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 742   /* Error or warning link info message.  */
 743   void (*einfo)
 744     (const char *fmt, ...);
 745   /* General link info message.  */
 746   void (*info)
 747     (const char *fmt, ...);
 748   /* Message to be printed in linker map file.  */
 749   void (*minfo)
 750     (const char *fmt, ...);
 751   /* This callback provides a chance for users of the BFD library to
 752      override its decision about whether to place two adjacent sections
 753      into the same segment.  */
 754   bfd_boolean (*override_segment_assignment)
 755     (struct bfd_link_info *, bfd * abfd,
 756      asection * current_section, asection * previous_section,
 757      bfd_boolean new_segment);
 758 };
 759 \f
 760 /* The linker builds link_order structures which tell the code how to
 761    include input data in the output file.  */
 762
 763 /* These are the types of link_order structures.  */
 764
 765 enum bfd_link_order_type
 766 {
 767   bfd_undefined_link_order,     /* Undefined.  */
 768   bfd_indirect_link_order,      /* Built from a section.  */
 769   bfd_data_link_order,          /* Set to explicit data.  */
 770   bfd_section_reloc_link_order, /* Relocate against a section.  */
 771   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 772 };
 773
 774 /* This is the link_order structure itself.  These form a chain
 775    attached to the output section whose contents they are describing.  */
 776
 777 struct bfd_link_order
 778 {
 779   /* Next link_order in chain.  */
 780   struct bfd_link_order *next;
 781   /* Type of link_order.  */
 782   enum bfd_link_order_type type;
 783   /* Offset within output section.  */
 784   bfd_vma offset;
 785   /* Size within output section.  */
 786   bfd_size_type size;
 787   /* Type specific information.  */
 788   union
 789     {
 790       struct
 791         {
 792           /* Section to include.  If this is used, then
 793              section->output_section must be the section the
 794              link_order is attached to, section->output_offset must
 795              equal the link_order offset field, and section->size
 796              must equal the link_order size field.  Maybe these
 797              restrictions should be relaxed someday.  */
 798           asection *section;
 799         } indirect;
 800       struct
 801         {
 802           /* Size of contents, or zero when contents should be filled by
 803              the architecture-dependent fill function.
 804              A non-zero value allows filling of the output section
 805              with an arbitrary repeated pattern.  */
 806           unsigned int size;
 807           /* Data to put into file.  */
 808           bfd_byte *contents;
 809         } data;
 810       struct
 811         {
 812           /* Description of reloc to generate.  Used for
 813              bfd_section_reloc_link_order and
 814              bfd_symbol_reloc_link_order.  */
 815           struct bfd_link_order_reloc *p;
 816         } reloc;
 817     } u;
 818 };
 819
 820 /* A linker order of type bfd_section_reloc_link_order or
 821    bfd_symbol_reloc_link_order means to create a reloc against a
 822    section or symbol, respectively.  This is used to implement -Ur to
 823    generate relocs for the constructor tables.  The
 824    bfd_link_order_reloc structure describes the reloc that BFD should
 825    create.  It is similar to a arelent, but I didn't use arelent
 826    because the linker does not know anything about most symbols, and
 827    any asymbol structure it creates will be partially meaningless.
 828    This information could logically be in the bfd_link_order struct,
 829    but I didn't want to waste the space since these types of relocs
 830    are relatively rare.  */
 831
 832 struct bfd_link_order_reloc
 833 {
 834   /* Reloc type.  */
 835   bfd_reloc_code_real_type reloc;
 836
 837   union
 838     {
 839       /* For type bfd_section_reloc_link_order, this is the section
 840          the reloc should be against.  This must be a section in the
 841          output BFD, not any of the input BFDs.  */
 842       asection *section;
 843       /* For type bfd_symbol_reloc_link_order, this is the name of the
 844          symbol the reloc should be against.  */
 845       const char *name;
 846     } u;
 847
 848   /* Addend to use.  The object file should contain zero.  The BFD
 849      backend is responsible for filling in the contents of the object
 850      file correctly.  For some object file formats (e.g., COFF) the
 851      addend must be stored into in the object file, and for some
 852      (e.g., SPARC a.out) it is kept in the reloc.  */
 853   bfd_vma addend;
 854 };
 855
 856 /* Allocate a new link_order for a section.  */
 857 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 858
 859 /* These structures are used to describe version information for the
 860    ELF linker.  These structures could be manipulated entirely inside
 861    BFD, but it would be a pain.  Instead, the regular linker sets up
 862    these structures, and then passes them into BFD.  */
 863
 864 /* Glob pattern for a version.  */
 865
 866 struct bfd_elf_version_expr
 867 {
 868   /* Next glob pattern for this version.  */
 869   struct bfd_elf_version_expr *next;
 870   /* Glob pattern.  */
 871   const char *pattern;
 872   /* Set if pattern is not a glob.  */
 873   unsigned int literal : 1;
 874   /* Defined by ".symver".  */
 875   unsigned int symver : 1;
 876   /* Defined by version script.  */
 877   unsigned int script : 1;
 878   /* Pattern type.  */
 879 #define BFD_ELF_VERSION_C_TYPE          1
 880 #define BFD_ELF_VERSION_CXX_TYPE        2
 881 #define BFD_ELF_VERSION_JAVA_TYPE       4
 882   unsigned int mask : 3;
 883 };
 884
 885 struct bfd_elf_version_expr_head
 886 {
 887   /* List of all patterns, both wildcards and non-wildcards.  */
 888   struct bfd_elf_version_expr *list;
 889   /* Hash table for non-wildcards.  */
 890   void *htab;
 891   /* Remaining patterns.  */
 892   struct bfd_elf_version_expr *remaining;
 893   /* What kind of pattern types are present in list (bitmask).  */
 894   unsigned int mask;
 895 };
 896
 897 /* Version dependencies.  */
 898
 899 struct bfd_elf_version_deps
 900 {
 901   /* Next dependency for this version.  */
 902   struct bfd_elf_version_deps *next;
 903   /* The version which this version depends upon.  */
 904   struct bfd_elf_version_tree *version_needed;
 905 };
 906
 907 /* A node in the version tree.  */
 908
 909 struct bfd_elf_version_tree
 910 {
 911   /* Next version.  */
 912   struct bfd_elf_version_tree *next;
 913   /* Name of this version.  */
 914   const char *name;
 915   /* Version number.  */
 916   unsigned int vernum;
 917   /* Regular expressions for global symbols in this version.  */
 918   struct bfd_elf_version_expr_head globals;
 919   /* Regular expressions for local symbols in this version.  */
 920   struct bfd_elf_version_expr_head locals;
 921   /* List of versions which this version depends upon.  */
 922   struct bfd_elf_version_deps *deps;
 923   /* Index of the version name.  This is used within BFD.  */
 924   unsigned int name_indx;
 925   /* Whether this version tree was used.  This is used within BFD.  */
 926   int used;
 927   /* Matching hook.  */
 928   struct bfd_elf_version_expr *(*match)
 929     (struct bfd_elf_version_expr_head *head,
 930      struct bfd_elf_version_expr *prev, const char *sym);
 931 };
 932
 933 struct bfd_elf_dynamic_list
 934 {
 935   struct bfd_elf_version_expr_head head;
 936   struct bfd_elf_version_expr *(*match)
 937     (struct bfd_elf_version_expr_head *head,
 938      struct bfd_elf_version_expr *prev, const char *sym);
 939 };
 940
 941 #endif